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Bubble nucleation,growth and coalescence during the 1997Vulcanian explosions of Soufrière Hills Volcano,MontserratT.Giachetti a ,b ,c ,⁎,T.H.Druitt a ,b ,c ,A.Burgisser d ,L.Arbaret d ,C.Galven eaClermont Université,UniversitéBlaise Pascal,Laboratoire Magmas et Volcans,BP 10448,F-63000Clermont-Ferrand,France bCNRS,UMR 6524,LMV,F-63038Clermont-Ferrand,France cIRD,R 163,LMV,F-63038Clermont-Ferrand,France dInstitut des Sciences de la Terre d'Orléans,Universitéd'Orléans,1A,rue de la Férollerie,45071Orléans Cedex 2,France eLaboratoire des Oxydes et Fluorures,Facultédes Sciences et Techniques,Universitédu Maine,Avenue Olivier Messiaen,72085Le Mans Cedex 9,Francea b s t r a c ta r t i c l e i n f o Article history:Received 29July 2009Accepted 5April 2010Available online 13April 2010Keywords:Vulcanian explosions Soufrière Hills vesiculationbubble nucleation bubble growth coalescenceamphibole boudinageSoufrière Hills Volcano had two periods of repetitive Vulcanian activity in 1997.Each explosion discharged the contents of the upper 0.5–2km of the conduit as pyroclastic flows and fallout:frothy pumices from a deep,gas-rich zone,lava and breadcrust bombs from a degassed lava plug,and dense pumices from a transition zone.Vesicles constitute 1–66vol.%of breadcrust bombs and 24–79%of pumices,all those larger than a few tens of µm being interconnected.Small vesicles (b few tens of µm)in all pyroclasts are interpreted as having formed syn-explosively,as shown by their presence in breadcrust bombs formed from originally non-vesicular magma.Most large vesicles (N few hundreds of µm)in pumices are interpreted as pre-dating explosion,implying pre-explosive conduit porosities up to 55%.About a sixth of large vesicles in pumices,and all those in breadcrust bombs,are angular voids formed by syn-explosive fracturing of amphibole phenocrysts.An intermediate-sized vesicle population formed by coalescence of the small syn-explosive bubbles.Bubble nucleation took place heterogeneously on titanomagnetite,number densities of which greatly exceed those of vesicles,and growth took place mainly by decompression.Development of pyroclast vesicle textures was controlled by the time interval between the onset of explosion –decompression and surface quench in contact with va-plug fragments entered the air quickly after fragmentation (∼10s),so the interiors continued to vesiculate once the rinds had quenched,forming breadcrust bombs.Deeper,gas-rich magma took longer (∼50s)to reach the surface,and vesiculation of resulting pumice clasts was essentially complete prior to surface quench.This accounts for the absence of breadcrusting on pumice clasts,and for the textural similarity between pyroclastic flow and fallout pumices,despite different thermal histories after leaving the vent.It also allowed syn-explosive coalescence to proceed further in the pumices than in the breadcrust bombs.Uniaxial boudinage of amphibole phenocrysts in pumices implies signi ficant syn-explosive vesiculation even prior to magma fragmentation,probably in a zone of steep pressure gradient beneath the descending fragmentation front.Syn-explosive decompression rates estimated from vesicle number densities (N 0.3–6.5MPa s −1)are consistent with those predicted by previously published numerical models.©2010Elsevier B.V.All rights reserved.1.IntroductionExplosive volcanic eruptions are driven by the nucleation,growth and coalescence of gas bubbles,followed by fragmentation of the magmatic foam into a suspension of pyroclasts and gas that is discharged at high velocities into the atmosphere.Studies of pyroclast textures,coupled with experimental and numerical approaches,have advanced understanding of these processes (Lensky et al.2004;Spieler et al.2004b;Adams et al.2006;Toramaru 2006;Gardner 2007;Cluzel et al.2008;Koyaguchi et al.2008and references therein),but many questions remain.One concerns the relative importance of homogeneous versus heterogeneous nucleation.Homogeneous nu-cleation requires gas supersaturations of at least several tens of MPa (Mangan and Sisson 2000;Mourtada-Bonnefoi and Laporte 2002;2004;Mangan et al.2004),whereas heterogeneous nucleation requires lower supersaturations (Hurwitz and Navon 1994;Gardner 2007;Cluzel et al.,2008).The degree of equilibrium between gas and melt during bubble growth also has an effect.Equilibrium degassing requires ef ficient volatile diffusion coupled with melt viscosity low enough to allow free gas expansion (Lyakhovsky et al.,1996;Liu and Zhang,2000;Lensky et al.,2004).High degrees of disequilibrium favour short-lived eruptions,whereas equilibrium allows more sustained fragmentation (Melnik and Sparks,2002;Mason et al.,2006).Another issue concerns the timing of bubble growth andJournal of Volcanology and Geothermal Research 193(2010)215–231⁎Corresponding author.Clermont Université,UniversitéBlaise Pascal,Laboratoire Magmas et Volcans,BP 10448,F-63000Clermont-Ferrand,France.E-mail address:giachettithomas@club-internet.fr (T.Giachetti).0377-0273/$–see front matter ©2010Elsevier B.V.All rights reserved.doi:10.1016/j.jvolgeores.2010.04.001Contents lists available at ScienceDirectJournal of Volcanology and Geothermal Researchj o u r n a l h o me p a g e :w w w.e l s ev i e r.c o m/l o c a t e /j vo l g e o r e scoalescence relative to fragmentation and eruption.Some authors postulate little growth following fragmentation(Klug and Cashman, 1991)whereas others envisage significant post-fragmentation growth(Thomas et al.1994;Kaminski and Jaupart,1997).Post-fragmentation bubble growth is largely controlled by melt viscosity, being important in mafic melts and less so in silicic melts with viscosities N108–109Pa s(Thomas et al.,1994;Gardner et al.,1996; Kaminski and Jaupart,1997).Bubble coalescence and connections control permeability acquisition and the ability of magma to outgas during ascent.Vesicle size distributions provide information on magma vesicu-lation history.Pumices commonly contain multiple vesicle popula-tions covering a large range of sizes(Klug and Cashman,1996;Klug et al.,2002;Adams et al.,2006)that may result from coalescence following a single nucleation event(Orsi et al.,1992;Klug and Cashman,1994,1996;Klug et al.,2002;Burgisser and Gardner,2005). Alternatively,each population may represent a distinct nucleation event,consistent with some ascent models which predict multiple events for viscous magma(Witham and Sparks,1986;Proussevitch and Sahagian,1996;Blower et al.,2001;Massol and Koyaguchi,2005). Small vesicles are commonly attributed to syn-explosive vesiculation that generates an exponential size distribution(Mangan et al.,1993; Klug and Cashman,1996;Klug et al.,2002;Adams et al.,2006).Size distributions of larger populations typically obey power laws usually attributed to coalescence(Klug et al.,2002;Houghton et al.,2003; Gurioli et al.,2005;Adams et al.,2006;Klug and Cashman,1996), although multiple nucleation events also generate power-law distributions(Blower et al.,2001).Magma decompression rates can be estimated from vesicle number densities assuming a unique and brief nucleation event(Toramaru,2006;Cluzel et al.,2008).Detailed studies of eruptive products are required to address these questions and provide ground truth for models.Most vesiculation studies to date have concerned Plinian eruptions.In this paper we study vesiculation during a sequence of well documented Vulcanian explo-sions at Soufrière Hills Volcano in1997.The explosions have been previously described(Druitt et al.,2002;Cole et al.,2002)and modelled (Melnik and Sparks,2002,Clarke et al.,2002;Formenti et al.,2003;Diller et al.,2006;Mason et al.,2006),and their products studied texturally (Formenti and Druitt,2003;Clarke et al.,2007)and chemically(Harford et al.,2003).A key feature was the eruption of pyroclasts of a wide range of types,including dense lava fragments,breadcrust bombs and pumices of different densities.Textural analysis,including a set of high-resolution vesicle-size distributions,enables us to recognize populations of vesicles formed by explosion decompression,quantify bubble nucleation mechanisms and decompression rates,and constrain the timing of bubble nucleation,growth and coalescence during,and immediately following,a typical explosion.In a companion paper we present measurements of groundmass water contents and reconstruct the state of the pre-explosion conduit(Burgisser et al.,in press).2.The1997Vulcanian explosions of the Soufrière Hills VolcanoThe eruption of Soufrière Hills Volcano(Fig.1)began phreatically in July1995;extrusion of lava began in November of the same year and continued intermittently until the time of writing.The explosions in 1997occurred every3–63h(mean of∼10h)in two periods:thirteen between4and12August,and seventyfive between22September and 21October(Druitt et al.,2002).Each consisted of an initial high-intensity phase lasting a few tens of seconds,followed by a waning phase lasting1–3h.Multiple jets were ejected at40–140m s−1during thefirst10–20s of each explosion,then collapsed back to form pumiceous pyroclasticflows that travelled up to6km from the crater (Formenti et al.,2003).Fallout of pumice and ash occurred from high (3–15km)buoyant plumes that developed above the collapsing fountains.Fallout andflow took place at the same time from individual explosions.Each explosion discharged on average8×108kg of magma,about two-thirds as pyroclasticflows and one-third as fallout, representing a conduit drawdown of0.5–2km(Druitt et al.,2002). Studies of quench pressures using microlite contents and glass water contents support a maximum drawdown of∼2km(Clarke et al.,2007; Burgisser et al.,in press).Each explosion started when magma overpressure exceeded the strength of an overlying degassed plug and a fragmentation front propagated down the conduit at a few tens of m s−1 (Druitt et al.,2002;Clarke et al.,2002;Melnik and Sparks,2002;Spieler et al.,2004a;Diller et al.,2006;Mason et al.,2006).After each explosion, magma rose up the conduit before the onset of a new explosion.The Soufrière Hills andesite contains phenocrysts of plagioclase, hornblende,orthopyroxene,magnetite,ilmenite and quartz set in rhyolitic glass.The pre-eruptive temperature was∼850°C(Devine et al., 2003).3.MethodolgyField work was carried out in2006and2008at three sites(Fig.1): sites1and2are situated on the fans of overlapping pyroclasticflow lobes from the explosions,and site3is a composite layer of fallout pumice from many explosions.Fallout pumices were also collected at a fourth site(site4;Fig.1)during an explosion in August1997.Field descriptions were made using a rock saw to cut perpendicular to any flow banding and parallel to any crystal fabric,and over100 representative pyroclasts were taken for laboratory study.Abundances of isolated and connected vesicles were measured on 2–5cm cubes cut from30breadcrust bombs and34flow and fall pumices using a Multivolume1305Helium Pycnometer and the method of Formenti and Druitt(2003),which is explained in the Supplementary electronic material.Separate measurements were made on the rims and cores of22 breadcrust bombs.Twenty-six of the pumice clasts ranged from lapilli to block size,all being b20cm in diameter.Measurements were also made on multiple core-to-rim samples from eight pumices N30cm in diameter. Texturally or compositionally banded pyroclasts were not included.Microscopic observations were made on the broken surfaces of pyroclast fragments using a Jeol JSM-591LV Scanning Electron Micro-scope(SEM)at an acceleration of15kV,and on polished epoxy-impregnated thin sections using the SEM and a stereomicroscope.Six samples representative(in terms of vesicularity and texture)of the pyroclast assemblage were chosen for high-resolution analysis of vesicle and crystal size distributions.Banded clasts,and those with a significant fraction of non-spherical vesicles,were excluded,thereby justifying use of a single,randomly oriented thin section for each sample.Vesicle and crystal size distributions were measured by image analysis in two dimensions(Toramaru,1990;Mangan et al.,1993; Klug and Cashman1994,1996;Klug et al.,2002;Adams et al.,2006;Shea et al.,2010).The technique,described fully in Appendix A,allowed objects as small as∼1µm to be measured.Differential epoxy penetration enabled us to distinguish interconnected from isolated vesicles.To represent the state of the magma immediately prior to the last discernible stage of coalescence,we manually‘decoalesced’neighbouring vesicles separated by a partially retracted wall.Volume distributions were assumed to equal area distributions(Klug et al.,2002).Volumetric number densities(N v)were calculated from area number densities(N a) using both the methods of Cheng and Lemlich(1983)and of Sahagian and Proussevitch(1998),which yield very similar values(Table1).Values of N v presented in this paper are those obtained using thefirst method,for reasons discussed in the Appendix A.4.Field descriptionsThe pyroclast assemblage consists predominantly of pumices of different colours,vesicularities and textures,with less than a few percent of breadcrust bombs and dense glassy lava clasts.Pyroclasts of all types were present in the pyroclasticflow deposits,although the216T.Giachetti et al./Journal of Volcanology and Geothermal Research193(2010)215–231relative proportions varied from lobe to lobe,while dense lava and breadcrust bombs were absent in the fallout.The samples described below come from several different explosions,and cannot be assigned to speci fic dates/times owing to the complex superposition of flow and fallout lobes from the many events.They represent the products of an ‘average ’explosion,as justi fied by (1)the first-order similarity of all the explosions (Druitt et al.,2002),and (2)the presence of the entire pyroclast spectrum in all pyroclastic flow lobes we examined.Pumices in the pyroclastic-flow deposits occur as lapilli and blocks up to N 1m in diameter with subangular-to-rounded shapes due to abrasion during transport.They range from beige,well vesiculated varieties,to grey,brown or black denser varieties (Fig.2a –b).A pink colouration affects the surfaces of many blocks,but rarely pervades the interiors.While the majority of pumices are texturally homoge-neous in hand specimen,some denser ones are flow banded with phenocryst alignment in the plane of banding.Rare compositional banding de fined by trails of disintegrated ma fic inclusions also occurs.All pumice clasts (as distinguished from breadcrust bombs)lack surface breadcrusting.This probably cannot be explained by abrasion,because breadcrust fragments are not observed in the flow matrices.All pumices smaller than ∼30cm lack radial gradients in vesicle abundance or size.However,some blocks larger than this exhibit visibly obvious radial gradients in vesicle size,with an outer 3–7-cm-thick rind with vesicles up to several mm,and a more coarsely vesicular interior containing vesicles up to an order of magnitude larger (Fig.2c).In some cases a crude cm-scale radial jointing affects the rind.The rind is inferred to represent the initial textural state of the pumice,while the interior records vesicle coarsening that took place during or after emplacement.The possibility that the interior represents the initial state,and that the rind developed by compaction during rolling in the pyroclastic flow,is not favoured because (1)the rinds texturally resemble the majority of smaller pumice blocks and lapilli,whereas vesicles in the interiors are abnormally coarse,and (2)no circumferential flattening of rind vesicles is observed.Many blocks also contain large voids up to several cm across,including anastamosing vesicle pipes and channels,ductile tears in the plane of flow banding,and curviplanar tears and cracks subparallel to clast margins (Fig.2d),which together account for b 10%of the total vesicularity.Fallout pumices are up to several cm in size and most preserve their original eruption –fragmentation shapes,unmodi fied by abrasion in pyroclastic flows or breakage on ground impact.They range in colour from white to brown and in shape from spheroidal to tabular,the latter comprising about three-quarters of the sample suite.Again,no surface breadcrusting is observed.Breadcrust bombs occur from a few cm to over a metre in diameter.They have vesicular interiors surrounded by darker,less vesicular b 10mm glassy rinds.A continuous range of textural varieties are observed between two endmembers.Coarsely breadcrusted bombs are relatively dense,with well de fined,dark-grey-to-black,poorly-to-non-vesicular rinds,broad,deep surface fractures de fining large polygons,and grey-to-brown vesicular interiors (Fig.2e –f).Finely breadcrusted bombs are less dense,with diffuse,pale vesicular rinds,finer polygonal networks of narrower,shallower surface fractures,and paler,commonly flow-banded interiors (Fig.2g –h).Some bombs that broke during eruption exhibit two generations of breadcrusting,the breakage surface being more finely breadcrusted than the original,outer surface of the bomb.Breakage is inferred to have exposed the already vesicular interior,which then developed a second generation of finer breadcrust-ing.Bombs were abraded during transport in the pyroclastic flows;most lack completely preserved breadcrust surfaces with sharp edges and corners,and partial rind removal,rounding of polygon edges,and abrasion of vesicular interiors are common.Clasts of black,essentially nonvesicular lava resembling the glassy rinds of the coarsely breadcrust bombs are interpreted as an integral component of the explosion-pyroclast suite.On the other hand,grey-to-brown holocrystalline lava and cinderblock clasts resembling typical dome rock are probably derived either from the crater walls or from earlier block-and-ash flow deposits traversed by the explosion pyroclastic flows.Fig.1.Map of Montserrat showing Soufrière Hills Volcano and sampling locations.Grey:pyroclastic flow deposits of the 1997Vulcanian explosions.217T.Giachetti et al./Journal of Volcanology and Geothermal Research 193(2010)215–231Fig.2.Pumices and breadcrust bombs from the explosions.a)Dark brown pumice with 60%vesicularity,b)Pale pumice with 76%vesicularity,c)Large grey pumice exhibiting a radial gradient in vesicularity,line marks the outer surface of the clast,d)Curviplanar tears and cracks subparallel to clast margins in a dense pumice,e –f)Exterior and cross section of a coarsely breadcrust-bomb,g –h)Exterior and cross section of a finely breadcrusted bomb.219T.Giachetti et al./Journal of Volcanology and Geothermal Research 193(2010)215–2315.Pyroclast vesicularitiesVesicularities of texturally homogenous pumice lapilli and blocks range from24to79vol.%(Fig.3)and correlate with colour,being lowest in darker pumices and higher in paler ones.The fraction of isolated vesicles(isolated divided by total vesicularity)is universally low(b0.25,with85%b0.1).Flow pumices cover the entire vesicularity range and have isolated fractions of0–0.13,whereas fallout pumices have vesicularities of43–72vol.%and isolated fractions of0.04–0.14,a single sample having0.25(Fig.3).No variation of either vesicularity or isolated vesicle fraction with clast size is observed.Vesicularity profiles across eight N30cm pumice blocks are shown in Fig.4.Four of these appeared homogeneous in thefield,and four had visually obvious radial gradients in vesicle size.The four homogeneous blocks(SHV4–12–13–22)lack significant gradients in vesicularity from core to rim,as anticipated from inspection.The four vesicle-size-graded blocks(SHV2–14–23–25),on the other hand, exhibit vesicularity gradients,but these vary from sample to sample and no systematic decrease in vesicularity from core to rim is evident.The coarse interiors of these pumices are no more vesicular than the morefinely vesicular rims.Textural coarsening in the interiors therefore took place without inflation,as consistent with the absence of surface breadcrusting.Breadcrust-bombs differ from pumices in that(1)their vesicular-ity range(20–66vol.%most lying between35and55%,Fig.3)is smaller,and highly vesicular(N66%)samples are not observed;and (2)the fraction of isolated pores(0.05–0.33,N80%being0.1–0.2) is higher than in pumices of similar vesicularity.Bomb rinds contain 1–25vol.%vesicles,most of which are isolated.Rind and interior vesicularities are broadly correlated(Fig.5).Coarsely breadcrusted bombs have the lowest vesicularities,both in rinds and interiors,and finely breadcrusted bombs are more vesicular.It is the existence of vesicular rinds onfinely breadcrusted bombs that gives these bombs their pale colours and make distinction between rind and interior less clear than in the coarsely breadcrusted bombs.Full tables of vesicularity data are provided as Supplementary electronic material.6.Microscopic vesicle texturesThe pyroclasts contain vesicles with a broad range of sizes set in microlite-bearing groundmass.In this section we focus on vesicles less than a few mm in diameter present in hand specimens,and distinguish three populations:small(less than a few tens ofµm),intermediate(few tens to a few hundreds ofµm)and large(few hundreds ofµm to a few mm).It is shown later that these three populations also have genetic significance.Vesicle textures in fallout andflow pumices are very similar and are described together.The large vesicles form interconnected networks with curved,scalloped walls indicative of rge vesicles in the more vesicular pumices are quasi-spherical to elliptical in shape. Those in dense pumices commonly have more ragged,fissure-like shapes,suggesting that perhaps they already existed prior to explosion. About15%of the large vesicles are angular voids associated with fractured amphibole phenocrysts(Fig.6a).Intermediate-sized vesicles in all pumices have variably rounded to ragged shapes and,like the large ones,form interconnected networks in three dimensions.In contrast, small vesicles are commonly spherical and many are isolated;they either form a‘matrix’in which the intermediate vesicles are dispersed (Fig.6b),or are situated in the walls separating the latter.In some samples the smallest isolated vesicles form sub-spherical clusters several tens of microns in diameter that protrude with bulbous, cauliform shapes into larger vesicles(Fig.6c;Formenti and Druitt, 2003).There is textural evidence that many vesicles of intermediate size formed by coalescence of the small vesicles(rather than pre-existing them),the process commonly being preserved quenched in progress (Fig.6d).The sizes of some intermediate vesicles appear to be inherited from the clusters of small vesicles when the latter coalesced while preserving the overall sub-spherical form of the cluster.Vesicles in pumices are commonly observed in spatial association with rge,angular voids are associated with fractured amphiboles,and have two endmember types:(1)voids in amphiboles boudinaged uniaxially in the plane offlow foliation,with well defined length-perpendicular fractures(Fig.7);(2)voids in amphiboles that are fractured both perpendicular and parallel to length,and the fragments dispersed around the vesicle margins in a manner suggestive of more isotropic expansion.In both types,crystal fragments arecommonlyFig.3.Plot of connected versus total vesicularity for all the samples of this vasamples from dome collapses at Soufrière Hills Volcano are also shown(Formenti andDruitt,2003).As connected vesicularities could not be determined for breadcrustbombs rinds,we just show the range of bulk vesicularities obtained(thick blackline).Fig.4.Vesicularity as a function of relative position inside large pumices(N30cm).Filled diamonds with solid lines are those pumices that were judged in thefield to betexturally homogeneous;squares with dashed lines are those that had larger vesicles inthe interior than in therind.Fig.5.Relationships between rind and interior vesicularities of breadcrust bombs,including both coarsely andfinely breadcrusted types.220T.Giachetti et al./Journal of Volcanology and Geothermal Research193(2010)215–231connected by thin,delicate threads of glass generated either by the bursting of melt inclusions,or by the pulling-out of thin,pre-existing melt films in incipient cracks.A single type of amphibole-associated void is commonly dominant within a given pumice block.Type 1is observed in ∼45%of pumices and type 2in ∼35%,the remaining ∼20%of pumices lacking voids associated with amphibole.Another common texture involves radial arrangements of stretched vesicles around phenocrysts of plagioclase or amphibole (Fig.6e).This is attributed to expansion of a magmatic foam around a rigid crystal;it cannot be due to heterogeneous bubble nucleation because in each case the vesicles are separated from the crystal by a thin glass film,showing that the crystal was not wetted by gas.Only in the case of titanomagnetite is it common to see vesicles in direct contact with crystals without intervening glass,suggesting that titanomagnetite provided nucleation sites for bubbles (Fig.8).There is abundant evidence that bubble coalescence was ongoing at all scales larger than a few µm at the time of sample quench:ovoid,neck-like connections with partially retracted walls between neighbouring vesicles (Fig.6d),wrinkling of thin vesicle walls (Fig.6f),the occurrence of thin glass fibres,and the interconnection of all but a fraction of the smallest vesicles.Minimum observed vesicle wall thicknesses are b 1µm.Breadcrust bomb rinds contain small,mostly isolated,vesicles that are irregularly distributed,being most abundant near rind-penetratingsurface fractures and around phenocrysts (Fig.9a,c).Areas of vesicle-free groundmass occur in the rinds of coarsely breadcrusted bombs,but not in those of the finely breadcrusted bombs.The lower limit of the rind is commonly marked by string-like networks of small vesicles,which then merge to form the more uniformly distributed vesicle population of the interior.The interiors of all bombs contain distinct large and small vesicle rge vesicles are invariably associated with fractured amphiboles,like those in the pumices.However,well developed uniaxial boudinage is never observed in breadcrust bombs,and the voids are mostly of the more isotropic type 2.Small vesicles are uniformly distributed throughout the bomb interiors (Fig.9b,d);they are mostly isolated,with quasi-spherical forms,and commonly occur in strings and clusters around crystals and large vesicles.Evidence for vesicle coalescence is abundant in bomb interiors,although less so than in pumices.7.Size distributions of vesicles and crystalsThe six samples chosen for analysis of vesicle and crystal size distributions were a coarsely breadcrusted bomb (BCP1),a finely breadcrusted bomb (BCP43),three pyroclastic-flow pumices (AMO29,AMO36and PV3),and a fallout pumice (R2).SeparatemeasurementsFig.6.SEM images of broken surfaces (a –d)and thin sections (e –f)of pumices.a)Angular void in a fractured amphibole phenocryst,the fragments being connected by thin glass fibres (white arrows),b)Visual evidence for three different size populations (large,intermediate and small)of vesicles in pumices,c)Cauliform-shaped clusters of small vesicles protruding into intermediate ones,d)Evidence for coalescence of small vesicles to form intermediate-sized ones,e)Microphenocryst of plagioclase surrounded by radiating,elongated vesicles,f)Wrinkling of vesicle wall indicative of the onset of rupture (white arrow).221T.Giachetti et al./Journal of Volcanology and Geothermal Research 193(2010)215–231。
CALPHAD软件介绍

Abstract
The phase-field method has become an important and extremely versatile technique for simulating microstructure evolution at the mesoscale. Thanks to the diffuse-interface approach, it allows us to study the evolution of arbitrary complex grain morphologies without any presumption on their shape or mutual distribution. It is also straightforward to account for different thermodynamic driving forces for microstructure evolution, such as bulk and interfacial energy, elastic energy and electric or magnetic energy, and the effect of different transport processes, such as mass diffusion, heat conduction and convection. The purpose of the paper is to give an introduction to the phase-field modeling technique. The concept of diffuse interfaces, the phase-field variables, the thermodynamic driving force for microstructure evolution and the kinetic phase-field equations are introduced. Furthermore, common techniques for parameter determination and numerical solution of the equations are discussed. To show the variety in phase-field models, different model formulations are exploited, depending on which is most common or most illustrative. c 2007 Elsevier Ltd. All rights reserved.
熊彼特增长模型英文教程--香港浸会大学-工商管理学院课件

innovators!
• James M. Utterback:
If a company only focuses on current product rather
than improving the quality, it will be swept out of market!
• Peter Druke:
12/4/2020
熊彼特增长模型英文教程--香港浸会大学 -工商管理学院
Literature Review of Schumpeterian Model
• How economy grows in Schumpeterian growth theory?
12/4/2020
熊彼特增长模型英文教程--香港浸会大学 -工商管理学院
Literature Review of Schumpeterian Model
*Capital-based growth theory emphasizes on the idea that the accumulation of capital (material capital and human capital) is the most important power to push the advancement of technology and economy.
market.
12/4/2020
熊彼特增长模型英文教程--香港浸会大学 -工商管理学院
Literature Review of Schumpeterian Model
• Creative destruction is the motivation of the development of capitalism. Additionally, the Schumpeterian growth theory which we define here does not order the process of innovation to be a process of creative destruction. Under the vertical innovation framework, process of innovation is a process of creative destruction, so old goods will be replaced by new goods. Whereas, under horizontal innovation framework, both the old and new goods will exist in the market.
A variational principle for two-fluid models

The formulae (2.2),(2.3) give the Lagrangian L as a function of variables
∂ Xi ∂ ϕi ∂ ϕi , , , ρ1 , ρ2 . Calculating the corresponding variational derivatives, ∂x ∂t ∂x we find the governing equations of motion : di Ki ∂ ui ∗ ∂W ) = 0, + < Ki − ui > + ∇∗ ( dt ∂x ∂ρi 3 (2.4)
i2 , (1.4) 2 a(ρ1 ρ2 ) where ε(ρ1 , ρ2 ) is a convex function with respect to ρ1 , ρ2 and a (ρ1 , ρ2 ) U (ρ1 , ρ2 , i) = ε (ρ1 , ρ2 ) + is a positive function. If the relative velocity w is small enough, the energy U is convex. The example (1.4) is a reasonable approximation of a general case as W is an analytic function of the velocities ui (and hence, an analytic function of w2 only). The term in equation (1.4) which is quadratic with respect to the relative velocity w , can be considered as the energy due to an added mass effect. We note that this quadratic dependence is usually used in the theory of bubbly liquids (V.L. Berdichevsky, 1983, J.A. Geurst, 1985, 1986). To derive the governing equations and the Rankine-Hugoniot conditions, it is not necessary to focus on the particular case (1.4).
层状双氢氧化物基复合材料的制备及其电化学性能的研究

层状双氢氧化物基复合材料的制备及其电化学性能的研究The Construction of Layered Double Hydroxides-Based Hybrid Materials for Electrochemical ApplicationAbstractTwo-dimensional (2D) materials have attracted increasing interest in electrochemical energy storage andconversion. As typical 2D materials, layered double hydroxides (LDHs) display large potential in this areadue to the facile adjustableof their composition, structure and morphology. Various preparationstrategies, including in situ growth, electrodeposition and layer-by-layer (LBL) assembly, have beendeveloped to directly modify electrodes by using LDHs materials. Moreover, several composite materialsbased on LDHs and conductive matrices have also been rationally designed and employed in supercapacitors, batteries and electrocatalysis with largely enhanced performances.This paper focus on the construction of LDHs-based composites and its application in electrocatalytic hydrolysis and electrochemical energy storage carried out in a series of trial and research.The controllable synthesis of LDHs-based composites was realized by the method of multi-step hydrothermal process and liquid phase self-assembly. As a result, the electrochemical performance was enhanced.The main contents of this paper are as following:(1) Study on the construction of NiFe LDH@NiCo2O4 compositesHerein, for the first time, we demonstrate NiFe-LDH ultrathin sheets with several atomic layers grown on nickel cobalt oxide (NiCo2O4) nanowire arrays as an efficient bifunctionalcatalyst toward both HER and OER reaction. Nickel (Ni) foam was used as the electrode scaffold support because of its earth abundance and porous three-dimensional structure.NiCo2O4, a typical OER electrocatalyst with high conductivity, was deposited on the Ni foam in the form of rhombus/hexagonal plates interconnected into perpendicular nanowire array morphology, efficientlyfacilitating electron transfer and electrolyte permeation. The electrical conductivity in NiCo2O4 has been believed to originate from the层状双氢氧化物基复合材料的制备及其电化学性能的研究presence of Ni3+ and the electron transfer between Ni2+ and Ni3+. Importantly, the surface of NiCo2O4was a Ni-rich layer, which served as the seed for the following hierarchical growth of NiFe-LDH, ensuring close contact and strong coupling at the interface.(2) Study on the properties of electrocatalytic water splitting of NiFe LDH@NiCo2O4 compositesHerein, the NiFe-LDH sheets were ultrathin of only several atomic layers, combined with its strong coupling with NiCo2O4 and the unique hierarchical structure, enabled the hybrid electrode a remarkable overall water splitting performance of only 1.60 V to achieve 10 mA cm-2 current in single alkaline KOH eletrolyte.Key words: Layered double hydroxides (LDHs),Electrocatalysis, Overall water splitting, Hydrogen evolution reaction, Oxygen evolution reaction,Heterostructure.Written by: Zhiqiang WangSupervised by: Prof. Fengxia GengProf. Xingwang Wang目录第一章文献综述 (1)1.1 引言 (1)1.2 LDHs及其复合材料的制备 (2)1.2.1 LDHs的基本结构 (2)1.2.2 LDHs的制备方法 (2)1.3 LDHs及其复合材料的应用 (3)1.3.1电催化水解中的应用 (3)1.3.2超级电容器中的应用 (10)1.4论文的选题思路、意义和主要工作 (15)1.4.1选题思路和意义 (15)1.4.2主要工作 (16)参考文献 (16)第二章超薄NiFe LDH纳米片与NiCo2O4纳米线杂化结构的构筑 (16)2.1 引言 (24)2.2 实验部分 (26)2.2.1 实验试剂 (26)2.2.2 仪器 (26)2.2.3 实验步骤 (27)2.3 结果与讨论 (28)2.3.1 SEM分析 (28)2.3.2 XRD和BET分析 (30)2.3.3 TEM分析 (32)2.3.4 EDS和Mapping分析 (33)2.3.5 XPS分析 (35)2.4 小结 (37)参考文献 (37)第三章NiFe LDH@NiCo2O4杂化结构的电催化全解水性能研究 (41)3.1 引言 (41)3.2 实验部分 (41)3.2.1 电化学测试 (41)3.3 结果与讨论 (42)3.3.1析氧反应分析 (42)3.3.2析氢反应分析 (44)3.3.3 全解水分析 (45)3.3.4 CV和EIS分析 (46)3.3.5电催化性能比较 (47)3.3.6 电催化性能的机理探究 (50)3.4 小结 (53)参考文献 (53)第四章结论和展望 (53)4.1 全文总结 (60)4.2 展望 (60)在读期间已发表或录用的论文 (62)致谢 (63)第一章文献综述1.1 引言能源在当今社会的发展中发挥着重要的作用,但近年来由传统能源煤、石油、天然气等资源的日益消耗,以及化石燃料等的大量使用所带来的生活环境的污染,以及温室气体的增加导致的海平面上升、酸雨的形成,使人类面临生存环境的恶化,不可再生能源的枯竭等多重威胁1-4。
不同文化维度国家的伦理

Ethics in countries with different culturaldimensions Ruth AlasABSTRACT.This paper compares ethics in countries with different cultural dimensions based on empirical data from12countries.The results indicate that dimensions of national culture could serve as predictors of the ethical standards desired in a specific society.The author divided societal cultural practices into desired and undesired practices.According to this study,ethics could be seen as the means for achieving a desired state in a society:for reducing some societal characteristics and increasing others.Finally,a model of the impact of cultural dimensions on desired ethical standards is proposed. KEY WORDS:ethical values,cultural dimensions,moti-vation theoryIntroductionCulture and the social world influence the values held by individuals.These values,in turn,affect attitudes and behavior(Bowditch and Buono,2001). Individual behavior is also directed by moral beliefs (Kohlberg,1978).Morality is the standards that an individual or group has about what is right and wrong,or good and evil(Velasquez,2002).Values have been defined as the principles or standards that people use,individually or collectively,to make judgments about what is important or valuable in their lives(McEwan,2001).People at thefirst stage of moral development try to be good people and seek to do what their fellows consider to be good (Kohlberg1978).All moral judgments are ethno-centric(Adler,1991)and what one ethnic group thinks about what is right or wrong depends on culture and environmental circumstances and is different across the cultures.Therefore,national culture plays a fundamental role in forming cultural values.This article aims to explore the impact that dimensions of national culture have on the impor-tance people place on the need for well-established ethical values.The results of previous studies have not indicated any clear connections(Furnham et al., 1994).The research question in this case is,which characteristics of national culture indicate a higher need for ethics.In order to discover the answer,the desire for well-established ethical standards and val-ues is compared with societal practices and values on the basis of the GLOBE study.In this paper,the author analyzes ethical theory in connection with cultural theory.A presentation of the theoretical framework is followed by an analysis of results from empirical studies in12countries,and finally,a model for the impact of cultural dimensions on the desire for ethics is proposed.Ethics and valuesEthical issues are all around those who work in organizations,whether we recognize them or not (Lawton,2000).Morality refers to the standards that an individual or group has about what is right and wrong,or good and evil.Moral standards are not established or changed by the decisions of particular authoritative bodies.Instead,the validity of moral standards rests on the adequacy of the reasons that are taken to support and justify them.So long as these reasons are adequate,the standards remain valid(Velasquez, 2002).Values have been defined as the principles or standards that people use,individually or collec-tively,to make judgments about what is important or valuable in their lives(McEwan,2001).ValuesJournal of Business Ethics(2006)69:237–247ÓSpringer2006 DOI10.1007/s10551-006-9088-3exist and are communicated through social con-nections and may vary in different cultures and dif-ferent countries(Fisher and Lovell,2003).A small number of core ideas or cognitions are present in every society about desirable end-states(Rokeach, 1973).Values form the basis for principles and vir-tues and are necessary to bring the ethical principles into moral practice(Lawton,2000).Ethics is the discipline that examines one’s moral standards or the moral standards of a society (Velasquez,2002).If something is ethical,this means it is of an acceptable standard in terms of one’s personal and social welfare.Research results from Estonian organizations indicate that the specific environment created during the Soviet era had an impact on peoples’value systems.A survey of values conducted in the second half of the90s indicated that Estonian business students underestimated social values when compared with Finnish students(Ennulo and Tu¨rnpuu,2001).National cultureSocial scientists use the term culture to mark a set of parameters for collectives that differentiate each collective in a meaningful way.The GLOBE study could be considered one of the most comprehensive studies of national cultures. It is a worldwide,multiphase,multi-method project, where170social scientists and management scholars from62cultures representing all major regions of the world are currently engaged in a long-term pro-grammatic series of cross-cultural studies(House and Javidan,2004).In the GLOBE study,culture is defined as shared motives,values,beliefs,identities, and interpretations or meanings of significant events that result from common experiences among members of collectives that are transmitted across generations(ibid.).There are nine core cultural dimensions in the GLOBE project(House and Javidan,2004): Uncertainty Avoidance is the extent to which members of an organization or society strive to avoid uncertainty by relying on established social norms, rituals,and bureaucratic practices.People in high uncertainty avoidance cultures actively seek to de-crease the probability of unpredictable future events that could adversely affect the operation of an organization or society and remedy the success of such adverse effects.Power Distance is the degree to which members of an organization or society expect and agree that power should be stratified and concentrated at higher levels of an organization or government. Institutional Collectivism is the degree to which organizational and societal institutional practices encourage and reward collective distribution of re-sources and collective action.In-Group Collectivism is the degree to which individuals express pride,loyalty,and cohesiveness in their organizations or families.Gender Egalitarianism is the degree to which an organization or society minimizes gender role dif-ferences while promoting gender equality. Assertiveness is the degree to which individuals in organizations or societies are assertive,confronta-tional,and aggressive in social relationships. Future Orientation is the degree to which indi-viduals in organizations or societies engage in future-oriented behaviors such as planning,investing in the future,and delaying individual or collective gratifi-cation.Performance Orientation is the degree to which an organization or society encourages and rewards group members for performance improvement and excellence.Humane Orientation is the degree to which indi-viduals in organizations or societies encourage and reward individuals for being fair,altruistic,generous, caring,and kind to others.These dimensions reflect two distinct kinds of cultural manifestations:values and practices. Empirical study of employee attitudes Methodology and sampleThe current article is based on data from two international surveys—from the GLOBE study and from the Denki Ringo research group.The author of this article organized these surveys in Estonian organizations.The data about cultural dimensions was taken from the Globe study(House et al.,2004).The core cultural dimensions were measured in terms of two238Ruth Alasmanifestations of culture—practices and values. Practices are measured using the responses of middle managers to questionnaire items concerning‘‘What Is,’’or‘‘What Are,’’common behaviors,institu-tional practices,proscriptions,and prescriptions. Values are expressed in response to questionnaire items concerning judgments of‘‘What Should Be,’’which are intended as a measure of the respondents’values concerning the practices reported by the respondents.A7-point scale was used,where‘1’indicated‘strongly disagree’and‘7’‘strongly agree’. In Estonia,170questionnaires were completed, 53%of the respondents were men and the average age of the respondents was35.5years.The average work experience was14.4years.The data about ethical values was collected during the Denki Ringo study(Ishikawa et al.,2006).This was a survey of attitudes in the electronics industry, the third phase of which was conducted between 1999and2001.A research partner from each country was requested to select two plants:one producing telecommunications equipment and the other electrical goods for household use.The author organized the survey of two plants in Estonia with 536respondents.There were4,874respondents from12countries (Appendix I).Ethical values were evaluated by using the question—‘What kind of society do people prefer?’The following items were given for evaluation:1.People are provided with a good materialstandard of living2.Everyone cooperates with each other in soli-darity3.People live life by observing well-establishedvalues and ethics4.Social equality among people is highly devel-oped5.Individuals can develop their lives with greatopportunities6.Social order is well kept with few criminaloffences7.People can live with peace of mind8.People can acquire all the results of theirown workA4-point scale was used where‘1’signifies‘very important’and‘4’‘not important’.This scale is or-ganized in the opposite direction to the scale used for the dimensions of organizational culture. ResultsThe results of both studies are brought together in the table in Appendix I.The desire for ethics is presented in the table in two ways—first,the average score that the respondents gave on the4-point scale regarding ethical values,and second,the ranking of ethical values from among all eight values given.The author proposes that culture and ethical values are connected and that by knowing a society’s culture helps us to predict how ethics is valued in that society.In order to predict the importance of ethics in this way the author analyzed the results from the ethics survey and the questionnaire on societal culture by using Linear Regression analyses. In the analyses,ethics was taken as a dependent variable and the nine scales of societal culture as independent variables.The analysis was performed twice,first with societal practices and second with values.The author calculated the coefficient Beta(ß), which enables us to predict how orientations of cul-ture forecast ethics.The Linear Regression analysis method revealed that almost18%of the variability in ethics could be explained by reference to the nine orientations of societal culture.This result was similar for both practices and values.For values:R2=0.185, F(9,4864)=123.628,p<0.001,for practices: R2=0.184,F(9,4864)=123.290,p<0.001.But there are differences in direction(Appendix II). Statistically significant connections between ethics and culture are also shown in Figure1.Groups according to ethical evaluationsAccording to the evaluation of ethical values and the position of ethical values in the value hierarchy, countries were divided into two groups.Thefirst group of six countries—China,Poland,Hong-Kong,South Korea,U.S.A.and Hungary—forms a group that valued ethics more highly.The other six countries—Japan,Italy,France,Finland,Estonia, and Spain—did not value ethics as highly as thefirst group.Ethics in countries with different cultural dimensions239A T-test for both groups indicated statistically significant differences in all societal practices and values(Appendix III).Due to the results from the comparative analysis of societal practices and values in the two groupings of countries according to a higher or lower desire for ethics,dimensions of national culture were also divided into two groups according to evaluations of societal practices by these two groups of countries (Figure2).Thefirst group was formed on the basis of cultural practices that were higher in the group that evaluated the need for ethics more highly. These practices were Assertiveness,Performance orientation,Power distance,and Group collectiv-ism.The second group was formed from practices that were lower in the group that evaluated the need for ethics more highly.These were Institu-tional collectivism,Future orientation,Gender egalitarianism,Humane orientation,and Uncer-tainty avoidance.In order tofind connections between ethical values and societal practices,a correlation analysis was performed for both groups of countries (Appendix IV).Conclusions and discussionThe research results indicate that lower scores in regard to some societal cultural practices are con-nected with a greater need for well-established ethical standards and values.Higher scores for these same scales are connected with less of a need for ethics.The author has called this group of practices desired societal practices.At the same time,there are also some societal cultural practices where highert t240Ruth Alasscores for these practices were connected with a low valuation of the same practices.This means,that people do not desire to have these practices in society to such a great extent.The higher scores for these practices are connected with a greater need for well-established ethical standards and values.The lower scores for these scales are connected with a lower need for ethics.People are satisfied with the current level of these practices.These could be called undesired societal practices.Thefirst group was formed from the practices Institutional collectivism,Future orientation,Gender egalitarianism,Humane orientation,and Uncertainty avoidance.The second group was formed from the practices Assertiveness,Performance orientation, Power distance,and Group collectivism.The model of the impact of cultural dimensions on the desire for ethics is presented in Figure3.Undesired practicesHigh assertiveness practices value aggressive,domi-nant,and tough behavior,and emphasize results over relationships.Lower assertiveness practices value people,relationships,cooperation,modesty,and tenderness(Den Hartog,2004,p.405).In many cultures people want less assertiveness in the interpersonal relationships in society than they have (ibid.,p.408).Performance orientation has an impact on the way a society defines success in adapting to external chal-lenges and on the way society manages inter-rela-tionships among its people(Javidan,2004,p.243). Societies that score higher on performance orienta-tion emphasize results more than people and value assertiveness,competitiveness and materialism.The scores for performance orientation practices tend to be related to the lack of a single dominant religion (ibid.).Societies that score lower on performance orientation tend to value societal and family rela-tions,loyalty and belongingness,and have a high respect for quality of life(ibid.,p.245).In the study of41countries no relationship was found between work ethics and improvement orientation(Lynn, 1991).There is a statistically significant negative correlation between performance orientation prac-tices and values(Javidan,2004,p.245).In societies that practice power distance,there is less emphasis on integrating different societal group-s—only a few people have access to resources,skills, and capabilities(Carl et al.,2004,p.531,536). Lower power distance enables better access to information and higher upward social mobility (ibid.,p.536).Power distance has a significant negative correlation with societal health and general satisfaction(ibid.,p.558).Higher power distance values predict greater corruption and lower civil liberties(ibid.,p.558).There is a statistically sig-nificant negative correlation between power distance practices and values(ibid.,p.541).In cultures with a high score for collectivism, group goals take precedence over individual goals and there is lower subjective well-being than in societies with lower collectivism(Gelfand et al., 2004,p.454).Realo and Allik(1999)found even three clearly distinguishable types of collectivism—relations with family,peers,and society.The institutional collectivism scale is highly distinct from the in-group collectivism scale—these scales are negatively correlated(Gelfand et al.,2004,pp. 467–468).This may explain why in-group collec-tivism is in the group of undesired practices and institutional collectivism is in the group of desired practices.In societies with high in-groupEthics in countries with different cultural dimensions241collectivism,authority is respected(ibid.,p.474). Societies with high institutional collectivism are less assertive and have less power distance(ibid.,p. 472).In-group collectivism has a statistically sig-nificant negative correlation with societal health, life expectancy,and general satisfaction.At the same time institutional collectivism has modest positive correlations with the same indicators(ibid., pp.484–485).This could explain why institutional collectivism and in-group collectivism belong to different groups of practices.To summarize,the desired practices scales have a statistically significant negative correlation with societal health,and in general,people wish to have less of these practices.These practices are positively correlated with each other.Where these practices were higher,the need for ethics was also higher. Where these practices were lower,the need for ethics was also lower.People feel that they need some kind of regulation mechanism in an aggressive society,a mechanism with strong interest groups and a strong hierarchy.They expect ethics and well-established values to be able to serve as this mecha-nism for achieving the desired society with lower levels of undesired practices.Desired practicesSocieties that show a higher score for future orien-tation tend to have individuals who are more intrinsically motivated(Ashkanasy et al.,2004,p. 302).Countries with higher-level future-oriented practices tend to enjoy a higher quality of life (ibid.,p.316).Past-oriented individuals and col-lectives do so by recalling and showing appreciation for prior learning,obligations,and traditions(Ke-ough et al.,1999).Societies with a higher time horizon for the past tend to have a higher time horizon for the present and future(Trompenaas and Hampden-Turner,1998).Societies with low future orientation display the need to move toward a more strategic and spiritually fulfilling perspective (Ashkanasy et al.,2004,p.306).Societies with more gender egalitarian practices have greater member longevity,knowledge,and standard of living(Emrich et al.,2004,p.368). Respondents would prefer less male dominated industries than they have now(ibid.,p.362).In societies with a high score for humane orien-tation,others are important and members of society are expected to provide social support for each other.Therefore,there are fewer psychological and pathological problems(Kabasakal and Bodur,2004, p.570).In societies with a low score for humane orientation,people are expected to solve their per-sonal problems on their own.In these societies people express the desire to reach a higher level of humane orientation in their relationships(ibid., p.575).Societies with high levels of uncertainty avoidance have a tendency to formalize their interactions with others and have less tolerance for the breaking of rules(De Luque and Javidan,2004,p.618).High uncertainty avoidance practices are positively correlated with societal health,life expectancy,and general satisfaction(ibid.,p.632).Cultures with weaker uncertainty avoidance practices have stronger uncertainty avoidance values(ibid.,p.621).To summarize,the scales of desired practices are positively correlated with societal health and general satisfaction.These scales are also mostly positively correlated with each other.When these practices were valued less,then the need for ethics was higher. If these practices were seen as highly represented in society,then the need for ethics was lower.People desire a society with such characteristics and if the reality is not consistent with this desire,then they hope that ethics will help them to achieve this kind of society.It could be stated here that ethics and well-established values are like a functional mechanism for achieving the desired society.If the desired state is achieved,the need for ethics is not so high any more. Maslow’s(1954)theory about the satisfaction of needs could serve as an explanation here.According to Maslow(1954),unsatisfied needs motivate people while satisfied needs are no longer motivating.As societal cultural values and practices have a significant and strong positive relationship with organizational culture and practices(Ashkanasy et al.,2004,p.324;Den Hartog,2004,p.426; Emrich et al.,2004,p.381;Gelfand et al.,2004, p.491;House and Javidan,2004,p.18;Javidan, 2004,p.266)the results of the current survey could be connected with organizational practices,values, and ethics.Based on this,in order to create a motivating work environment,managers could de-velop more humane and future-oriented practices,242Ruth Alaswhich give equal opportunities regardless of gender. Organizations should not be over-regulated—using too many rules and procedures.Instead,the inner climate of the organization could encourage creative solutions,risk taking,and learning from mistakes. Institutional collectivism instead of group collectiv-ism should be emphasized and organizational goals should dominate over group goals.Certain groups should not enjoy too much power so they can form ‘inner-groups’that actually lead the organization, and neither should they enjoy too many privileges. Managers should avoid aggressiveness in social relationships and also avoid high levels of power distance.Performance orientation should not be the only strong or dominant element in an organization as this may hinder the development of social capital. Following these guidelines will contribute to the creation of a learning environment,necessary for surviving and competing in uncertain environments.In order to strengthen ethical practices in orga-nizations,managers could build up levels of ethical competence in their companies and create a code of ethics.In order to develop such ethical competence, people should be trained to bring moral consider-ations into the decision making process.Writing a code of ethics is actually not enough on its own. Such a code can only start to work if it is integrated into the everyday management processes,if it is connected to pay,if ethical behavior is rewarded and there are in turn consequences for unethical behavior.To conclude,dimensions of national culture could serve as predictors of how people desire high ethical standards in a particular society.Ethics could be seen as the means for achieving a desired state in society—by reducing some practices and increasing others.Ethics in countries with different cultural dimensions243A P P E N D I X IC u l t u r a l p r a c t i c e s a n d v a l u e s t o g e t h e r w i t h e t h i c a l v a l u e sC o u n t r yP P P P P P P P P V V V V V V V V V N E V P E123456789123456789C h i n a 4281.2723.774.675.863.683.034.294.375.024.815.524.525.124.703.735.345.723.015.34F i n l a n d 3401.786.4.054.774.234.393.554.194.025.085.113.914.345.605.244.475.806.232.464.04F r a n c e 2091.828.4.444.204.663.743.813.604.435.684.663.575.275.885.354.715.916.102.964.65H u n g a r y 5091.513.4.713.635.313.314.023.393.505.473.263.424.575.585.744.655.485.972.594.74I t a l y 2341.988.4.123.754.993.343.303.663.665.453.853.875.205.766.014.885.576.112.514.52J a p a n 8272.3183.695.234.724.293.174.344.225.234.075.844.015.445.424.415.535.372.764.40K o r e a 5661.462.4.365.205.713.902.453.734.535.693.523.693.845.505.834.235.615.412.394.74P o l a n d 5391.415.4.114.515.553.233.943.673.965.093.713.954.245.695.174.535.326.063.194.75H o n g -K o n g 2511.455.4.534.035.333.883.263.724.694.944.174.804.355.115.524.275.385.713.004.52S p a i n 1481.625.4.393.875.533.523.063.294.005.533.954.015.255.825.664.825.635.852.234.80U S A 2481.474.4.393.875.533.523.063.294.005.533.954.015.255.825.664.825.635.852.234.80E s t o n i a 5211.646.4.043.714.794.203.603.393.875.164.013.904.334.955.044.735.365.682.874.31T o t a l 48741.674.154.445.183.803.363.794.105.294.024.344.405.475.404.465.515.762.734.62N o t e s :E V –E t h i c a l v a l u e s a c c o r d i n g t o D e n k i R i n g o r e s e a r c h P E –P o s i t i o n o f e t h i c s a m o n g o t h e r v a l u e s a c c o r d i n g t o D e n k i R i n g o r e s e a r c h P –s o c i e t a l p r a c t i c e s i n G L O B E s t u d y V –s o c i e t a l v a l u e s i n G L O B E s t u d y 1–A s s e r t i v e n e s s 2–I n s t i t u t i o n a l c o l l e c t i v i s m 3–I n -G r o u p C o l l e c t i v i s m 4–F u t u r e O r i e n t a t i o n 5–G e n d e r e g a l i t a r i a n i s m 6–H u m a n e O r i e n t a t i o n 7–P e r f o r m a n c e O r i e n t a t i o n 8–P o w e r D i s t a n c e 9–U n c e r t a i n t y A v o i d a n c e244Ruth AlasAPPENDIX IIConnections between ethical values and societal practices and values(according to standardizedregression coefficient Beta)Practices ValuesBeta Sig.Beta Sig. Assertiveness)0.2330.0000.7170.000 Institutional collectivism)0.2280.000)0.5490.000 In-Group collectivism)0.5160.000)0.3950.000 Future orientation)0.1920.0000.2010.000 Gender egalitarianism)0.0960.0050.7960.005 Humane orientation0.2990.0000.5420.000 Performance orientation0.1660.0000.3940.000 Power distance0.1290.0000.0670.003 Uncertainty avoidance)0.2960.0000.4470.000 Notes:All coefficients are statistically significant,p<0.01.APPENDIX IIIMeans of societal practices and values in groups with different ethical valuesPractices lower ethics N=2679Practiceshigher ethicsN=2374Valueslower ethicsN=2679Valueshigher ethicsN=2374Assertiveness 3.98 4.29 4.59 4.14 Institutional collectivism 4.48 4.41 4.45 4.37 Group collectivism 4.74 5.57 5.45 5.49 Future orientation 4.09 3.55 5.38 5.42 Gender egalitarianism 3.39 3.34 4.59 4.36 Humane orientation 3.89 3.70 5.57 5.45 Performance orientation 4.06 4.14 5.74 5.79 Power distance 5.28 5.31 2.70 2.76 Uncertainty avoidance 4.23 3.83 4.39 4.83 Notes:All scales are statistically significantly different according to T-test,p<0.01.Bold indicates higher societal practices and values compared to the other group.APPENDIX IVCorrelation coefficients for ethical values and societal practices in both groupsLower ethics N=2679Higher ethics N=2374 Assertiveness)0.281**0.122** Institutional collectivism0.298**)0.053** Group collectivism)0.036)0.098** Future orientation0.089)0.018 Gender egalitarianism)0.241**0.025Ethics in countries with different cultural dimensions245ReferencesAdler,M.J.:1991,Desires Right&Wrong:The Ethics of Enough.Macmillan Publishing Company. Ashkanasy,N.,V.Gupta,and M.S.Mayfield:2004,‘Future Orientation’,in R.House et al.(eds.), Culture,Leadership,and Organizations(The GLOBE Study of62Societies,Sage Publications,Inc.),pp.282–342.Bowditch,J.L.and A.F.Buono:2001,A Primer on Orga-nizational Behavior,5th edn.(John Wiley&Sons,Inc.). Carl,D.,V.Gupta and M.Javidan:2004,‘Power dis-tance’,in R.House et al.(eds.),Culture,Leadership, and Organizations(The GLOBE Study of62Societies, Sage Publications,Inc.),pp.513–563.De Luque,M.S.and M.Javidan:2004,‘Uncertainty avoidance’,in R.House et al.(eds.),Culture,Leader-ship,and Organizations(The GLOBE Study of62 Societies,Sage Publications,Inc.),pp.602–653. Den Hartog,D.N.:2004,‘Assertiveness’,in R.House et al.(eds.),Culture,Leadership,and Organizations(The GLOBE Study of62Societies,Sage Publications, Inc.),pp.395–436.Emrich,C.G.,F.L.Denmark and D.N.Den Hartog: 2004,‘Cross-cultural differences in gender egalitari-anism’’,in R.House et al.(eds.),Culture,Leadership, and Organizations(The GLOBE Study of62Societies, Sage Publications,Inc.),pp.343–394.Ennulo,J.and L.Tu¨rnpuu:2001,ÔAn Intercultural Comparison of Management Values among Business School Students and TeachersÕ,Trames5(4),336–344. Fisher,C.and A.Lovell:2003,Business Ethics and Values (Prentice Hall).Furnham,A.,B.D.Kirkcadly and R.Lynn:1994,ÔNa-tional Attitudes to Competitiveness,Money,and Work Among Young People:First,Second,and Third World DifferencesÕ,Human Relations47(1),119–132.Gelfand,M.J.,D.P.S.Bhawuk,L.H.Nishii and D.J.Bechtold:2004,‘Individualism and Collectivism’,in R.House et al.(eds.),Culture,Leadership,and Orga-nizations(The GLOBE Study of62Societies,Sage Publications,Inc.),pp.473–512.House,R.J.,P.J.Hanges,M.Javidan,P.W.Dorfman and V.Gupta(eds.):2004,Culture,Leadership,and Organizations(The GLOBE Study of62Societies,Sage Publications,Inc.).House,R.J.and M.Javidan:2004,‘Overview of Globe’, in R.J.House,P.J.Hanges,M.Javidan,P.W.Dorfman and V.Gupta(eds.),Culture,Leadership,and Organizations(The GLOBE Study of62Societies,Sage Publications,Inc.)pp.9–48.Ishikawa A.,C.Mako and C.Warhurst(eds.):2006, Work and employee representation:workers,firms and unions.Tokyo:Chuo University Press.Javidan,M.:2004,‘Performance Orientation’,in R.House et al.(eds.),Culture,Leadership,and Organiza-tions(The GLOBE Study of62Societies,Sage Pub-lications,Inc.),pp.239–281.Kabasakal,H.and M.Bodur:2004,‘Humane Orientation in Societies,Organizations and Leader Attributes’,in R.House et al.(eds.),Culture,Leadership,and Orga-nizations(The GLOBE Study of62Societies,Sage Publications,Inc.),pp.564–601.Keough,K.A.,P.G.Zimbardo and J.N.Boyd:1999,ÔWho’s Smoking,Drinking,and Using Drugs?Time Perspective as a Predictor of Substance UseÕ,Basic and Applied Social Psychology21(2),149–164. Kohlberg,L.:1978,‘Revision in the Theory and Practice of Moral Development’,Moral Development,Josey-Bass, 2(86).Lawton,A.:2000,Ethical Management for the Public Ser-vices.Open University Press.Lynn,R.:1991,The Secret of Miracle Economy(SAU, London)APPENDIX IVContinuedLower ethics N=2679Higher ethics N=2374 Humane orientation0.298**)0.118** Performance orientation0.178**)0.052** Power distance)0.0170.082** Uncertainty avoidance)0.082**)0.114**Note:**Correlation is significant at the0.01level(2-tailed).The connections are opposite here because of the difference of the evaluation scales.246Ruth Alas。
大五人格模型和大三人格模型的比较

LOOKING BEYOND THE FIVE-FACTOR MODEL: COLLEGE SELF-EFFICACY AS A MODERATOR OF THE RELATIONSHIPBETWEEN TELLEGEN’S BIG THREE MODEL OF PERSONALITY AND HOLLAND’S MODEL OF VOCATIONAL INTEREST TYPESBy Elizabeth A BarrettThe Five-Factor Model (FFM) of personality and Tellegen’s Big Three Model of personality were compared to determine their ability to predict Holland’s RIASEC interest types. College self-efficacy was examined as a moderator of the relationship between Tellegen’s Big Three model and the RIASEC interest types. A sample of 194 college freshmen (i.e., less than 30 credits completed) was drawn from the psychology participant pool of a mid-sized Midwestern university. Instruments included the International Personality Item Pool (IPIP) to measure the FFM; the Multidimensional Personality Questionnaire Brief Form (MPQ-BF) to measure Tellegen’s Big Three model of personality; the College Self-Efficacy Inventory (CSEI) to measure college self-efficacy; and the Self Directed Search (SDS) to measure Holland’s RIASEC model of vocational interests. Findings from correlational analyses supported previous research regarding relationships among the FFM and the RIASEC interest types, and relationships among Tellegen’s Big Three and the RIASEC interest types. As hypothesized and tested via regressions for each of the six interest types, Tellegen’s Big Three model predicted all six vocational interests types (p < .001 for all), while the FFM only predicted two types at p < .05. College self-efficacy did not moderate the relationship between Tellegen’s Big Three and the RIASEC interest types. Implications and future research are discussed.ACKNOWLEDGEMENTSSeveral people have assisted me with the completion of this thesis, and I wish to thank the following people for their help and guidance:In acknowledgement of excellent guidance of this project, Dr. McFadden chairperson, whose knowledge and encouragement pushed the progress of this thesis and my development as a writer and researcher.Dr. Adams and Dr. Miron, committee members, who graciously gave their time and shared their expertise in the completion of this project, specifically, Dr. Adams who aided with the data analysis of this project and worked through multiple analysis problems with me.iiTABLE OF CONTENTSPage INTRODUCTION (1)THEORY AND LITERATURE REVIEW (4)Personality Traits and Vocational Interests Defined (4)The Five-Factor Model (FFM) of Personality (4)Holland’s Theory of Vocational Interest Types (5)Overlap between the FFM and RIASEC (7)Criticisms and Limitations of the FFM (9)Looking Beyond the FFM: Tellegen’s Big Three Model of Personality (11)Comparing Tellegen’s Big Three and the FFM (14)College Self-Efficacy: Moderating Role (16)Conclusion (20)METHOD (22)Participants (22)Procedure (23)Measures (23)Methods of Data Analysis and Missing Data (27)RESULTS (29)Descriptive Statistics (29)Relationship between the FFM and the RIASEC Interest Types:Hypothesis 1a-1e (29)Relationship between Tellegen’s Big Three and the RIASEC InterestTypes: Hypothesis 2a-2c (30)Comparing the FFM and Tellegen’s Big Three: Hypothesis 3 (31)College Self-Efficacy as Moderator: Hypothesis 4 (32)iiiTABLE OF CONTENTS (continued) DISCUSSION (34)The Relationship between the FFM and the RIASEC Interest Types (34)The Relationship between Tellegen’s Big Three and the RIASECInterest Types (35)Comparing Tellegen’s Big Three and the FFM (36)College Self-Efficacy as a Moderator (37)Limitations (38)Implications and Future Research (39)Conclusions (41)APPENDIXES (42)Appendix A: Tables (42)Table A-1. Holland’s Vocational Personality Types Described: RIASEC.. 43 Table A-2. Overlap Between the FFM and RIASEC (44)Table A-3. The Big Three of Tellegen measured by the MPQ: HigherOrder and Primary Trait Scales (45)Table A-4. Means, Standard Deviations, and Intercorrelations (47)Table A-5. Regression Analysis: Realistic Interest Type as DependentVariable (48)Table A-6. Regression Analysis: Investigative Interest Type as DependentVariable (48)Table A-7. Regression Analysis: Artistic Interest Type as DependentVariable (49)Table A-8. Regression Analysis: Social Interest Type as DependentVariable (49)Table A-9. Regression Analysis: Enterprising Interest Type as DependentVariable (50)Table A-10. Regression Analysis: Conventional Interest Type asDependent Variable (50)Table A-11. Hierarchical Multiple Moderated Regression Analysis:Realistic Interest Type as Dependent Variable (51)Table A-12. Hierarchical Multiple Moderated Regression Analysis:Investigative Interest Type as Dependent Variable (51)Table A-13. Hierarchical Multiple Moderated Regression Analysis:Artistic Interest Type as Dependent Variable (52)Table A-14. Hierarchical Multiple Moderated Regression Analysis: SocialInterest Type as Dependent Variable (52)Table A-15. Hierarchical Multiple Moderated Regression Analysis:Enterprising Interest Type as Dependent Variable (53)ivTABLE OF CONTENTS (continued)Table A-16. Hierarchical Multiple Moderated Regression Analysis:Conventional Interest Type as Dependent Variable (53)Appendix B: Figure (54)Figure B-1. Holland’s Hexagonal Model (55)Appendix C: Information Sheet and Surveys (56)REFERENCES (73)vINTRODUCTIONPersonality traits and vocational interests are two major individual difference domains that influence numerous outcomes associated with work and life success. For example, research has shown that congruence between personality traits and one’s vocation is related to greater job performance and job satisfaction (Barrick, Mount, & Judge, 2001; Hogan & Blake, 1999; Zak, Meir, & Kraemer, 1979). Additionally, specific personality traits are hypothesized to play a role in determining job success within related career domains (Sullivan & Hansen, 2004). Personality is a relatively enduring characteristic of an individual, and therefore could serve as a stable predictor of why people choose particular jobs and careers.Personality traits and vocational interests are linked by affecting behavior through motivational processes (Holland, 1973, 1985). Personality traits and vocational interests influence choices individuals make about which tasks and activities to engage in, how much effort to exert on those tasks, and how long to persist with those tasks (Holland, 1973, 1985; Mount, Barrick, Scullen, & Rounds, 2005). Research has shown that when individuals are in environments congruent with their interests, they are more likely to be happy because their beliefs, values, interests, and attitudes are supported and reinforced by people who are similar to them (Mount, Barrick, Scullen, & Rounds, 2005). Furthermore, research has demonstrated that personality and interests may shape career decision making and behavior; personality and interests guide the development ofknowledge and skills by providing the motivation to engage in particular types of activities (Sullivan & Hansen, 2004).As relatively stable dispositions, personality traits influence an individual’s behavior in a variety of life settings, including work (Dilchert, 2007). Individuals often prefer jobs requiring them to display behaviors that match their stable tendencies. Thus individuals will indicate a liking for occupations for which job duties and job environments correspond to their personality traits. Such a match between personal tendencies and job requirements can support adjustment and eventually occupational success, making the choice of a given job personally rewarding on multiple levels (Dilchert, 2007).People applying for jobs need to try to understand themselves more fully in order to determine if they will be satisfied with their career choices based on their personality traits. This process can be aided by vocational counselors who conduct vocational assessments. The purpose of vocational assessment is to enhance client self-understanding, promote self-exploration, and assist in realistic decision making (Carless, 1999). According to a model proposed by Carless (1999), career assessment is based on the assumption that comprehensive information about the self (e.g., knowledge of one’s personality) in relation to the world of work is a necessary prerequisite for wise career decision making.Self-efficacy beliefs--personal expectations about the ability to succeed at tasks (Bandura, 1986)--are often assessed by vocational counselors. This study examines college self-efficacy--belief in one’s ability to perform tasks necessary for success incollege (Wang & Castaneda-Sound, 2008). Self-efficacy determines the degree to which individuals initiate and persist with tasks (Bandura, 1986), and research has found that personality may influence exploration of vocational interests, through high levels of self-efficacy (Nauta, 2007).There is an abundance of literature supporting that the Five-Factor Model (FFM) (discussed in depth in following sections) of personality predicts Holland’s theory of vocational interest types; however, there is little literature that extends beyond use of the Five-Factor Model. This is due to the adoption of the FFM as an overriding model of personality over the past fifteen years. However, as will be demonstrated later, several criticisms of the model have surfaced. In light of these criticisms the purpose of this study is to extend the existing literature that has established links between the FFM and Holland’s vocational interest types, while examining the relationship between an alternate personality model, Tellegen’s Big Three (as measured by the Multidimensional Personality Questionnaire (MPQ)) and Holland’s types. Furthermore, this study will examine the moderating role that college self-efficacy plays on the relationship between Tellegen’s Big Three and Holland’s interest types.THEORY AND LITERATURE REVIEWPersonality Traits and Vocational Interests DefinedPersonality traits refer to characteristics that are stable over time and are psychological in nature; they reflect who we are and in aggregate determine our affective, behavioral, and cognitive styles (Mount, Barrick, Scullen, & Rounds, 2005). Vocational interests reflect long-term dispositional traits that influence vocational behavior primarily through one’s preferences for certain environments, activities, and types of people (Mount, Barrick, Scullen, & Rounds, 2005).The Five-Factor Model (FFM) of PersonalityThe FFM, often referred to as the Big Five personality dimensions, is a major model that claims personality consists of five dimensions: Openness to Experience (i.e., imaginative, intellectual, and artistically sensitive), Conscientiousness (i.e., dependable, organized, and persistent), Extraversion (i.e., sociable, active, and energetic), Agreeableness (i.e., cooperative, considerate, and trusting), and Neuroticism, sometimes referred to positively as emotional stability (i.e., calm, secure, and unemotional) (Harris, Vernon, Johnson, & Jang, 2006; McCrae & Costa, 1986; McCrae & Costa, 1987; Mount, Barrick, Scullen, & Rounds, 2005; Nauta, 2004; Sullivan & Hansen, 2004). The FFM provides the foundation for several personality measures (e.g., NEO-PI, NEO-PI-R, NEO-FFI) that have proved to be valid and reliable and are widely utilized in research today (Costa & McCrae, 1992). There appears to be a large degree of consensusregarding the FFM of personality and the instruments used to measure the model. For instance, the FFM has been shown to have a large degree of universality (McCrae, 2001), specifically in terms of stability across adulthood (McCrae & Costa, 2003) and cultures (DeFruyt & Mervielde, 1997; Hofstede & McCrae, 2004, McCrae, 2001).Holland’s Theory of Vocational Interest TypesHolland’s theory of vocational interests has played a key role in efforts to understand vocational interests, choice, and satisfaction.Holland was very clear that he believed personality and vocational interests are related:If vocational interests are construed as an expression of personality, then theyrepresent the expression of personality in work, school subjects, hobbies,recreational activities, and preferences. In short, what we have called ‘vocational interests’ are simply another aspect of personality…If vocational interests are anexpression of personality, then it follows that interest inventories are personalityinventories. (Holland, 1973, p.7)Vocational interest types, as classified by Holland, are six broad categories (discussed later in the section) that can be used to group occupations or the people who work in them. Holland’s theory of vocational interest types and work environments states that employees’ satisfaction with a job as well as propensity to leave that job depends on the degree to which their personalities match their occupational environments (Holland, 1973, 1985). Furthermore, people are assumed to be most satisfied, successful, and stable in a work environment that is congruent with their vocational interest type. Two ofHolland’s basic assumptions are: (a) individuals in a particular vocation have similar personalities, and (b) individuals tend to choose occupational environments consistent with their personality (Holland, 1997).A fundamental proposition of Holland’s theory is that, when differentiated by their vocational interests, people can be categorized according to a taxonomy of six types, hereinafter collectively referred to as RIASEC (Holland, 1973, 1985). Holland’s theory states that six vocational interest types--Realistic, Investigative, Artistic, Social, Enterprising, and Conventional (RIASEC)--influence people to seek environments which are congruent with their characteristics (Harris, Vernon, Johnson, & Jang, 2006; Holland, 1973, 1985; Nauta, 2004; Roberti, Fox, & Tunick, 2003; Sullivan & Hansen, 2004; Zak, Meir, & Kraemer, 1979). Holland used adjective descriptors to capture the distinctive characteristics of each interest type (Hogan & Blake, 1999). These are summarized in Table A-1. Holland’s approach to the assessment of vocational interest types was based on the assumption that members of an occupational group have similar work-related preferences and respond to problems and situations in similar ways (Carless, 1999).Realistic types like the systematic manipulation of machinery, tools, or animals. Investigative types have interests that involve analytical, curious, methodical, and precise activities. The interests of Artistic types are expressive, nonconforming, original, and introspective. Social types want to work with and help others. Enterprising types seek to influence others to attain organizational goals or economic gain. Finally, Conventional types are interested in systematic manipulation of data, filing records, or reproducing materials (Tokar, Vaux, & Swanson, 1995).According to Holland’s theory, these interest types differ in their relative similarity to one another, in ways that can be represented by a hexagonal figure with the types positioned at the six points (see Figure B-1). Adjacent types (e.g., Realistic and Investigative) are most similar; opposite types (e.g., Realistic and Social) are least similar, and alternating types (e.g., Realistic and Artistic) are assumed to have an intermediate level of relationship (Holland, 1973, 1985; Tokar, Vaux, & Swanson, 1995).Overlap between the FFM and RIASECMany studies provide evidence of the links between the FFM of personality and the RIASEC interest types. An extensive review of the research investigating the links between the FFM and the RIASEC types identified ten studies that found Extraversion predicts interest in jobs that focus on Social and Enterprising interests. Ten studies showed Openness to Experience predicts interest in jobs that focus on Investigative and Artistic interests. Six studies found Agreeableness predicts interest in jobs that focus on Social interest; six studies showed Conscientiousness predicts interests in jobs that focus on Conventional interests; and one study found Neuroticism predicts interests in jobs that focus on Investigative interests (see Table A-2 for the citations). One discrepancy in this research has been Costa and McCrae’s claims that the FFM applies uniformly to all adult ages, but Mroczek, Ozer, Spiro, and Kaiser (1998) found substantial differences between the structures emerging from older individuals as compared to undergraduate students, in that the five factor structure failed to emerge in the student sample (i.e., agreeableness failed to emerge) as it did with the older sample.All of the links discussed between the FFM of personality and the RIASEC interest types provide the foundation for hypotheses 1a – 1e. Hypotheses 1a – 1e will add to the literature, previously discussed, by assessing current college students early in their college careers. These are the people who have the potential to be most influenced by vocational and career counselors. Given that research has found a discrepancy in FFM profiles of younger and older individuals, it is important to test its efficacy in predicting vocational interests.Hypothesis 1a (H1a): Extraversion will significantly positively correlate withSocial and Enterprising types, but not Realistic, Investigative, Artistic, andConventional types.Hypothesis 1b (H1b): Openness to Experience will significantly positivelycorrelate with Investigative and Artistic types, but not Realistic, Conventional,Social, and Enterprising types.Hypothesis 1c (H1c): Agreeableness will significantly positively correlate withSocial types, but not Realistic, Conventional, Enterprising, Investigative, andArtistic types.Hypothesis 1d (H1d): Conscientiousness will significantly positively correlatewith Conventional types, but not Realistic, Enterprising, Investigative, Social, and Artistic types.Hypothesis 1e (H1e): Neuroticism will significantly negatively correlate withInvestigative types, but not Realistic, Enterprising, Conventional, Social, andArtistic types.Criticisms and Limitations of the FFMThe whole enterprise of science depends on challenging accepted views, and the FFM has become one of the most accepted models in personality research. Many critiques of the FFM ask “Why are there five and only five factors? Five factor protagonists say: it is an empirical fact…via the mathematical method of factor analysis, the basic dimensions of personality have been discovered.” (McCrae & Costa, 1989, p. 120). Has psychology as a science achieved a final and absolute way of looking at personality or is there a way to further our conceptualization of personality? In the article by Costa and McCrae (1997) explaining the anticipated changes to the NEO in the new millennium, they anticipate only minor wording modifications and simplifications. Thus it appears as if the FFM is viewed as a final or almost final achievement (Block, 2001). One claimed benefit of the FFM is evidence of heritability is strong for all 5 factors, but evidence is strong for all personality factors studied; it does not single out the Costa and McCrae factors (Eysenck, 1992). In other words, all the criteria suggested by Costa and McCrae are necessary but not sufficient to mark out one model from many which also conform to this criteria.The debate that has been most prominent over the past 15 years, and which has probably attracted the most attention, concerns the number and description of the basic, fundamental, highest-order factors of personality. Evidence from meta-analyses of factorial studies provide evidence that three, not five personality factors, emerge at the highest level of analysis (Royce & Powell, 1983; Tellegen & Waller, 1991; Zuckerman, Kuhlman, & Camac, 1988; Zuckerman, Kuhlman, Thornquist, & Kiers, 1991).Altogether, Eysenck (1992) has surveyed many different models, questionnaires and inventories, reporting in most cases a break-down into 2 or 3 major factors; but never 5. Additionally, Jackson, Furnham, Forde, and Cotter (2000) and Tellegen (1985) have contradicted Costa and McCrae’s (1995) assertions that a five-factor model seems most appropriate, with results showing that a three-factor solution is both more clear and parsimonious.Another critique of the FFM lies in its development. The initial factor-analytic derivations of the Big Five were not guided by explicit psychological theory, and therefore some have asked the question, “Why these five?” (e.g., Revelle, 1987; Waller & Ben-Porath, 1987). As Briggs (1989) points out, the original studies leading to the FFM “prompted no a priori predictions as to what factors should emerge, and a coherent and falsifiable explanation for the five factors has yet to be put forward” (p. 249).A further developmental critique of the FFM is the lack of lower order factors. Theoretically, factors exist at different hierarchical levels, and the FFM only measures five higher order factors (Block, 2001). The FFM operates at a broadband level to measure the main (i.e., higher order) categories of traits (McAdams, 1992). Within each of the five categories, therefore, may be many different and more specific traits, as traits are nested hierarchically within traits (McAdams, 1992).Another limitation of the FFM lies in researchers’ inability to consistently link the personality traits to the Holland interest types. Research has found that although there is a significant overlap between the FFM and RIASEC interest types, the RIASEC types do not appear to be entirely encompassed by the Big-Five personality dimensions (Carless,1999; Church, 1994; DeFruyt & Mervielde, 1999; Tokar, Vaux, & Swanson, 1995). Three personality dimensions in the FFM predict the RIASEC types, but there is less evidence to support that the other two predict the RIASEC types. Specifically, there appears to be significant overlap with Conscientiousness, Openness, and Extraversion in predicting the RIASEC interest types, but less research has been able to find links between Agreeableness and Neuroticism with the RIASEC interest types. This is a limitation of the FFM in relating to vocational interests (Costa, McCrae, & Holland, 1984; Gottfredson, Jones, & Holland, 1993; Tokar, Vaux, & Swanson, 1995).Looking Beyond the FFM: Tellegen’s Big Three Model of PersonalityIn light of these criticisms of the FFM, it seems attention could be paid to alternate models of personality to investigate the dimensions underlying Holland’s interest types. The literature base is sparse here, and alternative personality models warrant further study, particularly with regard to vocational interests (Blake & Sackett, 1999; Church, 1994; Larson & Borgen, 2002; Staggs, Larson, & Borgen, 2003). One such model is Tellegen’s Big Three which addresses many of the criticisms of the FFM.Many vocational psychology researchers use the Big Five model of personality, often measured by the NEO-PI or NEO-PI-R, but less often the Big Three model of personality measured by the Multidimensional Personality Questionnaire (MPQ) is used (Tellegen, 1985; Tellegen & Waller, 1991). This model of personality resulted from ten years of research on focal dimensions in the personality literature (Tellegen, 1985; Tellegen & Waller, 1991). Tellegen’s (1985; Tellegen & Waller, 1991) Big Three modeldefines three higher order factors. These represent the clusters of items from a factor analysis that composed the three higher order traits. The lower order factors consist of items clustered in each of the higher order factors. The higher order factors are: Positive Emotionality (PEM), Negative Emotionality (NEM), and Constraint (CT) (Tellegen, 1985; Tellegen & Waller, 1991). These higher order traits correlate minimally with one another and encompass 11 lower order traits. Refer to Table A-3 for a description of the three higher order traits and the 11 lower order traits.There are only three published studies that have examined the Big Three model as relating to vocational interests. Blake and Sackett (1999) reported that the Artistic type moderately related with the MPQ Absorption lower order trait (Larson & Borgen, 2002). The Social type negatively related to the MPQ Aggression lower order trait; the Enterprising type related moderately to the MPQ Social Potency lower order trait; and the Conventional type related moderately to the MPQ Control lower order trait.Staggs, Larson, and Borgen (2003) also analyzed the lower order traits, specifically, as opposed to the higher order factors of PEM, NEM, and CT. They identified seven personality dimensions that have a substantial relationship with vocational interests: Absorption predicted interest in Artistic occupations; Social Potency predicted interest in Enterprising occupations; Harm Avoidance predicted interest in science and mechanical activity occupations; Achievement predicted interest in science and mathematic occupations; Social Closeness predicted interest in mechanical activity occupations; Traditionalism predicted interest in religious activities; and Stress Reaction predicted interest in athletic careers. Staggs, Larson, and Borgen (2003) used a collegestudent sample, but were not studying the RIASEC types; they were using a different conceptualization of vocational interests as measured by the Strong Interest Inventory which measures General Occupational Themes.Larson and Borgen (2002) found that the PEM factor was more strongly correlated with Social interests than with Enterprising interests; however, PEM did strongly correlate with all six RIASEC types (p < .001). This finding shows strong evidence that the PEM higher order trait relates to the RIASEC types. Larson and Borgen (2002) also found that the CT factor was negatively related to Realistic and Artistic interest types, and that the NEM factor was negatively related to Artistic interest types. Larson and Borgen (2002) utilized a sample of “gifted” adolescent students, which is a very limited and non-generalizable sample. In contrast, the current study tests a freshman college student sample, which is more generalizable to the population of students who are seeking vocational guidance.The links between the MPQ and the RIASEC interest types are under-researched. Although some vocational research has utilized the MPQ, more needs to be done to determine the relationships between Tellegen’s Big Three and Holland’s RIASEC interest types. However, the research provides support for the idea that there are alternative personality dimensions (i.e., Tellegen’s Big Three), outside of the FFM, that can significantly predict vocational interests, in particular the RIASEC types. Hypotheses 2a – 2c will test relationships between the Tellegen’s Big Three (as measured by the MPQ-BF) and the RIASEC interest types.Hypothesis 2a (H2a): The PEM factor will significantly positively correlate with all six RIASEC types.Hypothesis 2b (H2b): The CT factor will significantly negatively correlate withRealistic and Artistic types, but not with Investigative, Social, Enterprising, andConventional types.Hypothesis 2c (H2c): The NEM factor will significantly negatively correlate with Artistic types, but not with Investigative, Social, Enterprising, Realistic, andConventional types.Comparing Tellegen’s Big Three and the FFMAn earlier discussion proposed criticisms of the FFM. In light of these criticisms an alternate personality model was considered: Tellegens’ Big Three, measured by the MPQ. This model of personality resolves all the previous criticisms of the FFM: five versus 3 factors, lack of lower order factors, and model development issues.Tellegen’s (1985) understanding of personality differs from the conception of the FFM. Tellegen believes personality can be summed by three overriding traits or factors versus the 5 factors of the FFM. This is an inherent difference in the two models of personality, which guided the development of instruments used to measure these models, in terms of a three versus a five factor structure. Furthermore, Tellegen (1985) utilized a bottom-up approach to development of the MPQ, in which constructs were based on iterative cycles of data collection and item analyses designed to better differentiate the primary scales. In contrast, Tupes and Chrtistal (1961) emphasized deductive, top-down。
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LETTER
doi:10.1038/nature18306
High-efficiency two-dimensional Ruddlesden– Popper perovskite solar cells
Hsinhan Tsai1,2*, Wanyi Nie1*, Jean-Christophe Blancon1, Constantinos C. Stoumpos3,4,5, Reza Asadpour6, Boris Harutyunyan4,5, Amanda J. Neukirch1, Rafael Verduzco2,7, Jared J. Crochet1, Sergei Tretiak1, Laurent Pedesseau8, Jacky Even8, Muhammad A. Alam6, Gautam Gupta1, Jun Lou2, Pulickel M. Ajayan2, Michael J. Bedzyk4,5, Mercouri G. Kanatzidis3,4,5 & Aditya D. Mohite1
We further investigated the crystallinity of the perovskite films using the grazing incidence X-ray diffraction (GIXRD) technique (Fig. 1c). Three dominant planes were observed at diffraction angles (2θ, Cu Kα) of 14.20°, 28.48° and 43.28°, representing the (BA)2(MA)3Pb4I13 crystallographic planes (111), (202) and (313), respectively, in both of the films16. The full-width at half-maximum (FWHM) as a function of hot-casting temperature for the (202) plane is plotted in Fig. 1d; the FWHM of the (202) plane is greatly reduced from 0.63° to 0.29° when the casting temperature increase from room temperature to 110 °C, and remains constant at 0.27° for higher temperatures. The diffraction background and FWHM for each plane are also reduced for the hot-cast film (Fig. 1c and Fig. 1d inset). These results suggest that the crystallinity of the hot-cast films is superior to that of the room-temperature-cast films and becomes optimal at 110 °C. This stark difference in the observed GIXRD patterns motivated in-depth crystallography measurements using grazing incidence wide-angle X-ray scattering (GIWAXS) imaging, and is discussed with reference to Fig. 2.
control of the stoichiometry. Here we focus on the n = 4 member (Fig. 1a, lower panel) unless otherwise stated.
The layered perovskite thin films were fabricated using a hot-casting technique (see Methods for details)18. Briefly, the spin coating of the perovskite precursors was performed on a preheated substrate (fluorine-doped tin oxide (FTO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)). The temperature of the substrate was varied from room temperature to 150 °C, as illustrated in the images shown in Fig. 1b. The hot-cast films look uniform and reflective, suggesting that the film is ideal for fabrication of planar devices. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to compare the morphologies between roomtemperature-cast and hot-cast films (Extended Data Fig. 1a–d). From the AFM images, the hot-cast films show substantially larger grains (about 400 nm) in son to the room-temperature spincoated films (about 150 nm), resulting in a much more compact and uniform thin film. SEM images further confirm the much lower density of pinholes in the hot-cast films in comparison to RT cast films. The presence of pinholes makes it challenging to fabricate working planar-type devices.
Three-dimensional organic–inorganic perovskites have emerged as one of the most promising thin-film solar cell materials owing to their remarkable photophysical properties1–5, which have led to power conversion efficiencies exceeding 20 per cent6,7, with the prospect of further improvements towards the Shockley– Queisser limit for a single‐junction solar cell (33.5 per cent)8. Besides efficiency, another critical factor for photovoltaics and other optoelectronic applications is environmental stability and photostability under operating conditions9–15. In contrast to their three-dimensional counterparts, Ruddlesden–Popper phases—layered two-dimensional perovskite films—have shown promising stability, but poor efficiency at only 4.73 per cent13,16,17. This relatively poor efficiency is attributed to the inhibition of out-of-plane charge transport by the organic cations, which act like insulating spacing layers between the conducting inorganic slabs. Here we overcome this issue in layered perovskites by producing thin films of near-single-crystalline quality, in which the crystallographic planes of the inorganic perovskite component have a strongly preferential out-of-plane alignment with respect to the contacts in planar solar cells to facilitate efficient charge transport. We report a photovoltaic efficiency of 12.52 per cent with no hysteresis, and the devices exhibit greatly improved stability in comparison to their three-dimensional counterparts when subjected to light, humidity and heat stress tests. Unencapsulated two-dimensional perovskite devices retain over 60 per cent of their efficiency for over 2,250 hours under constant, standard (AM1.5G) illumination, and exhibit greater tolerance to 65 per cent relative humidity than do three-dimensional equivalents. When the devices are encapsulated, the layered devices do not show any degradation under constant AM1.5G illumination or humidity. We anticipate that these results will lead to the growth of single-crystalline, solution-processed, layered, hybrid, perovskite thin films, which are essential for high-performance opto-electronic devices with technologically relevant long-term stability.