Is high amplitude propagated

合集下载

High Energy Positrons and the WMAP Haze from Exciting Dark Matter

Recently, a number of diﬀerent experiments have made measurements which are consistent with excesses in positrons and/or electrons that may be indicative of a dark matter signal. Two of these (HEAT and the WMAP haze) are indicative of high energy particles, whereas the results of INTEGRAL/SPI are indicative of low energy particles.
arXiv:0802.2922v1 [astro-ph] 20 Feb 2008
I. INTRODUCTION
An overwhelming amount of evidence has established cold dark matter (CDM) as the standard paradigm for the missing matter of the universe. Beginning with early observations of velocity dispersions of galaxies in clusters [1], and later measurements of galactic rotation curves [2, 3], CDM has been supported by numerous additional observations. Some of these include strong lensing of background galaxies [4], and x-ray emission from galaxy clusters [5], the combination of CMB and type Ia supernovae data [6], measurements of the distributions of galaxies [7, 8], as well as the highly remarkable recent study of the bullet cluster [9].

Proximal colonic

Proximal colonic propagating pressure waves sequences and their relationship with movements of content in the proximal human colonP.G.DINNING,M.M.SZCZESNIAK&I.J.COOKDepartment of Gastroenterology,The St.George Hospital,University of New South Wales,Sydney,AustraliaAbstract Abnormal colonic motor patterns have been implicated in the pathogenesis of severe constipation. Yet in health,the mechanical link between movement of colonic content and regional pressures have only been partially deﬁned.This is largely due to current methodological limitations.Utilizing a combination of simultaneous colonic manometry,high-resolution scintigraphy and a quantitative technique for detect-ing discrete episodicﬂow,our aim was to examine the propulsive properties of colonic propagating sequences (PS)in the healthy colon.In six healthy volunteers a nasocolonic manometry catheter was positioned to record colonic pressures at7.5cm intervals from ter-minal ileum to the splenicﬂexure.With subjects positioned under a gamma camera,30MBq of99m Tc sulfur colloid was instilled into the terminal ileum, 22.5cm proximal to the ileocolonic junction.Isotopic images were recorded(10s/frame)and synchronized with the manometric trace.In the proximal colon we identiﬁed137antegrade PSs,of which93%were deemed to be associated temporally with movements of luminal content.Low amplitude PSs,with compo-nent pressure waves between2mmHg and5mmHg, were as likely to be associated with colonic move-ments as higher amplitude PSs.As such there was no correlation between the amplitude of the PS and the temporal relationship with colonic movements. Within the proximal colon,24retrograde PSs were identiﬁed,23of which were associated with retro-grade movements of colonic content.We conclude that proximal colonic PSs are highly propulsive and are a major determinant of proximal colonicﬂow.Keywords automated analysis,colon,propagating sequences,scintigraphy,transit.INTRODUCTIONColonic propagating pressure waves or propagating sequences(PS)are reported to be an important deter-minant of luminal propulsion and defecation.1–9 Altered colonic PS characteristics may represent important markers of colonic dysfunction.10–13How-ever as manometry can be an insensitive measure of wall motion,particularly in large calibre chambers such as the colon where non-lumen occluding contractions are common,14the clinical signiﬁcance that can attributed to manometricﬁndings remains undetermined.Animal studies have shown that colonic PSs have a close temporal relationship with actual movements of content.15–18Human studies on the other hand have either failed to demonstrate a relationship,16shown a relatively poor relationship1or been unable to establish a real time correlation between all pressure events and ﬂow.4–7Unlike animal studies that can utilize pro-longed,continuous radiology,human studies are con-strained by the radiation exposure and therefore rely on scintiscanning that can be limited by relatively slow frame,capture rates.4–7Other factors,which may hinder human studies,include a reliance upon the relatively insensitive method of visual analysis of isotopicﬂow,1and in all studies a substantial inter-sidehole distance yields a relativelyÔlow resolutionÕmanometric recording which inevitably underscores the frequency of propagating events.19Combined,Address for correspondenceDr.Philip Dinning,Department of Gastroenterology,The StGeorge Hospital,Kogarah,NSW,2217Australia.Tel:+61291132208;fax:+61291133993;e-mail:P.dinning@.auReceived:10September2007Accepted for publication:24October2007A section of this work has been presented in abstract form atthe International Motility Society meeting in Barcelona Spain(October5–8,2003).Dinning PG,Szczesniak M,Cook IJ.The relationships amongcaecalﬁlling and ileal and colonic propagating sequences.Neurogastroenterol Mot2003;15:591–681:A299.Neurogastroenterol Motil(2008)20,512–520doi:10.1111/j.1365-2982.2007.01060.xÓ2008The AuthorsJournal compilationÓ2008Blackwell Publishing Ltd512these technical deﬁciencies limit the precision with which any temporal relationship between pressure and movement can be detected.Recently we developed and validated a quantitative, scintigraphic method able to accurately detect discrete episodic movements of colonicﬂow on a moment-by-moment basis over prolonged periods.20Therefore, by combining this high-resolution scintigraphic technique with closely spaced recording sites in the proximal human colon we aimed to determine the relative propulsive nature of colonic PSs.Speciﬁcally, we hypothesized that;(i)all colonic PSs propel luminal content;and(ii)episodes of movements of content that are associated with low amplitude PSs are detectable by high resolution scintigraphy.METHODSSubjectsWe studied six healthy subjects(two male and four female)with a mean age of22.7±2.8years.All had normal bowel habits,deﬁned as between two bowel movements a day and one bowel movement every 2days.None was taking regular medications including laxatives.None had a history of prior abdominal surgery,other than appendectomy.All gave written, informed consent and the study was approved of by the Human Ethics Committees of the South Eastern Area Health Service,Sydney and the University of New South Wales.Manometric techniqueWe used a21lumen(16recording sideholes)4.5m long extruded silicone perfused manometric assembly (DentSleeve,Wayville,South Australia,Australia), with an overall diameter of 4.2mm.Each of the recording lumina had an internal diameter of0.4mm with an inter-sidehole distance of7.5cm.Tantalum slugs imbedded with silicone adjacent to each of the sideholes permittedﬂuoroscopic localization of each sidehole.In addition2–4MBq of57Co was sealed within the silicone catheter at sideholes1,4,7,10, 13and16to allow localization of sideholes during scintiscanning.A silicone balloon at the tip of the catheter,which could be inﬂated and deﬂated with water through two0.4mm lumina,assisted catheter passage through the gut.The catheter was rendered radio-opaque along its entire length byﬁlling the larger centre core(I.D. 1.9mm)with a1:1mixture of barium sulphate and sylgard(silicone surfactant, Wilbur-Ellis Company,San Francisco,CA,USA).The recording lumina were perfused with degassed distilled water preceded by a CO2ﬂush to ensure removal of all air bubbles from the catheter,thus minimizing compliance.21A low compliance pneu-mohydraulic perfusion pump drove the perfusate at 0.15mL/min(DentSleeve).Pressures were measured from each sidehole with16external pressure trans-ducers(Abbott Critical Care Systems,North Chicago, IL,USA).Signals were ampliﬁed and digitized at 10Hz by preampliﬁers(AqcKnowledge III Soft-ware,BIOPAC Systems,Inc.Santa Barbara,CA, USA).We have previously demonstrated that the rise rate characteristics afforded by a catheter of this nature is adequate for recording colonic pressure waves.9Experimental protocolThe technique of nasocolonic manometry of the unprepared colon has been described in detail else-where.9,19All subjects ate standard meals(breakfast: 500Kcal,15%protein,34%fat,51%carbohydrate; lunch and dinner:1000kCal,24%protein,43%fat, 33%carbohydrate)during the positioning of the cath-eter on days1and 2.On day3a continuous manometric recording commenced at0800h after a breakfast500kCal taken at0745h.With subjects supine point markers were placed on the right iliac crest and xiphisternum in order to monitor body movement during scintiscanning.Anterior and poster-ior isotope images were then recorded in13-min time intervals at10s/frame(80frames per13min)by a scintillation camera(Picker Prisim2000XP;Picker International,Cleveland,OH,USA)with a medium energy collimator.The camera was linked to a dedi-cated computer.There was a2-min gap between each 13-min recording interval,during which data was saved.At the commencement of each13min scinti-graphic recording period a mark was registered on the manometric trace,which facilitated synchronization of scintigraphic and manometric recording.Data were recorded for4–6h.Distinction between ileal and colonic pressure trac-ings was readily apparent from the characteristic morphology of the tracings from the two regions. Compressing the tracings to better appreciate the characteristic ileal motor pattern facilitated this pro-cess.At the commencement of the scintigraphic recording,30MBq of99m Tc sulphur colloid in1mL of saline was instilled into the terminal ileum,via a recording sidehole in the manometry catheter,approx-imately22.5cm proximal to the ileocolonic junction. The total effective radiation dose to each subject fromVolume20,Number5,May2008Determinants of colonicﬂow Ó2008The AuthorsJournal compilationÓ2008Blackwell Publishing Ltd513ﬂuoroscopy and scintigraphy including the cobalt markers within the catheters was equivalent to 4.8mSv.Data analysisManometric deﬁnitions and analysis The proximal colon,for the purposes of analysis,was divided into eight regions extending from cecum(region1),through hepaticﬂexure(region4)to the splenicﬂexure(region 8).A PS was deﬁned as an array of three or more pressure waves recorded from adjacent recording sites which displayed a conduction velocity of0.2–12cm/s. Propagating sequences were further qualiﬁed by the terms antegrade or retrograde,depending upon the direction of propagation.9,22Antegrade PSs were sub-classiﬁed as high amplitude propagating sequences (HAPS)if the amplitude of at least one component propagating pressure wave was‡116mmHg.This value represents the mean plus two standard devia-tions of propagating pressure waves from the mid colon in our previously collected healthy control data.19In order to address the hypothesis that low ampli-tude PSs are propulsive of content,a further sub-group was deﬁned asÔlow amplitude PSÕif the PS comprised two or more component pressure waves with a trough to peak amplitude between2mmHg and5mmHg but which satisﬁed the same conduction velocity criteria as for PS described above.Quantitative(high resolution)identiﬁcation of isotope movement Quantitative analysis of isotope movement was performed using the MrVoxel image analysis soft-ware.23This technique has been validated and is described in detail previously.20Brieﬂy,a composite image was obtained by combining all80frames cap-tured during a13-min epoch by the camera positioned anterior to the abdomen.This yielded an overall image of isotope distribution within the small and large bowel, enabling it to be divided anatomically into regions of interest(ROI).Using this composite image,ROI were constructed to measureﬂow across the(i)mid-ascend-ing colon and(ii)mid-transverse colon(Fig.1).Con-struction of the ROIs was established for each subject. Isotopeﬂow through each region was measured inde-pendent ofﬂow through adjacent regions.Applying these ROIs to the geometric mean of the anterior and posterior images,produced time-activity curves.In the absence of noise and gross movement of the subject,the slope of the regional time-activity curves may be interpreted as the rate of net inﬂow or outﬂow from the corresponding region.For the pur-poses of this study,declining or increasing activity over three or more consecutive frames were considered to indicate a potential movement of isotope into or out of that region respectively.For each of these potential movements,the index of theﬁrst and last frame were recorded on a grid,on which each box of the grid represented a10s frame.Grids from adjacent ROIs within a13-min recording period were compared. Where three or more consecutive frames demonstrat-ing declining counts coincided with three or more frames demonstrating increasing counts in an aboral adjacent region,it was deemed that antegradeﬂow had occurred while the converse indicated retrogradeﬂow. False-positiveﬂow episodes were removed from anal-ysis through a previously validatedﬂow value index.20 Correlation between scintigraphically-determined ﬂow and propagating sequences The next step was to assign the labelÔpropulsiveÕorÔnon-propulsiveÕto each PS by determining whetherﬂow occurred as a direct consequence of each PS.The time of onset of each PS was superimposed on theﬂow grids(refer quantitative scintigraphic analysis above).A scintigraphically-determinedﬂow episode was considered to be associ-ated temporally with a PS if the onset of the PS occurred not more than three frames(30s)prior to and not more than two frames(20s)after the onset of the isotope movement.This range was determined from our previous study in which we simulatedﬂow between adjacent ROI in a phantom model and ran the computer analytical algorithm to detect these simu-lated isotope movements.Our data showed that the computer algorithm placed the onset of95%these movements within a time window commencing30s Figure1Composite images of the technician in the(A) terminal ileum and proximal colon and(B)throughout the colon.The composite image was used to mark the regions of interest(ROI).These ROI were used to measureﬂow across (C)the mid-ascending colon and(D)mid-transverse colon.P.G.Dinning et al.Neurogastroenterology and MotilityÓ2008The AuthorsJournal compilationÓ2008Blackwell Publishing Ltd514prior and up to20s following the actual isotope movement(i.e.,total time window of50s).20All PSs found to be temporally associated with isotope move-ment in this manner were deﬁned asÔpropulsive PSsÕ, the remainder were consideredÔnon-propulsiveÕ. Following stratiﬁcation of PS in this manner,the pressure wave amplitude,conduction velocity of component propagating pressure waves and extend of propagation were compared between propulsive and non-propulsive PS in order to deﬁne how these vari-ables relate to the phenomenon of propulsion by a PS. Statistical analysis and determination of association probability To test whether a genuine association existed between PSs and episodicﬂow the association probability was calculated as previously described.24,25 Each of the13min grids upon whichﬂow episodes and PSs were detailed(see above)were divided into con-secutive60s periods(six10s frames).The number of these60s periods varied amongst regions and volun-teers and was dependant upon the presence of isotope within the region.The selection of a60s period was based upon the50s window in which our computer algorithm placed the onset of95%of isotope move-ments in our pilot studies20(see previous section). However,as the scintigraphic computer retrieving data from the collimator had to acquire data over13min intervals it was necessary to choose a time window that was a multiple of13and as close to50s as pos-sible.Hence,a60s time window was adopted.The number of these60s periods varied amongst regions and volunteers and was dependant upon the presence of isotope within the region.All60s periods were then evaluated for the existence ofﬂow(F+:ﬂow present;F):ﬂow absent)and for the presence of a PS (PS+:propagating sequence present;PS):propagating sequence absent).A60s period was considered to be ﬂow positive ifﬂow occurred over a minimum of two consecutive frames within the60s period.A60s period was considered to be PS positive if the point in time at which the PS was initiated occurred within the period.From these data a2·2contingency table was constructed with fourﬁelds:Field one contained the number of PSﬂow positive60s periods(PS+F+),ﬁeld two the number ofﬂow positive episodes without PSs (PS)F+),ﬁeld3the number of PS positive periods withoutﬂow(PS+F))andﬁeld4the number of periodswithoutﬂow or PSs(PS)F))(Fig.2).Individual contin-gency tables were constructed for each of the colonic regions(ascending and transverse colon)in each of the subjects.The next stage of the analysis determined the X1 relation between the number of PS positive60s periods and the total number of60s periods and X2 relation between the number of PSﬂow positive periods and the total number of Flow positive periods. If X2<X1it indicated that PSs coincided signiﬁcantly less than could be expected if the association between PSs andﬂow occurred by chance.In such instancesthevalue of1was assigned to the P value resulting in a ﬂow associated probability of0.If X2>X1then the calculation ofﬂow associated probability was possible. FisherÕs Exact Test was then determined from the contingency table to test the probability(P value)that the observed association between PSs andﬂow occurred by chance.Theﬂow associated probability was calculated as(1)P value)·100%.A value of>95% deﬁned as an association between the PS andﬂow,a value<95%indicated no association.The statistical comparison of the degree of associa-tion between PSs andﬂow was performed with|2 parison between the amplitude and velocity of PS associated withﬂow and those that were not associated was performed with a standard two-tailed T test.Data are presented as mean±SD. RESULTSCatheter placementThe catheter tip was located at the mid-transverse colon(n=2),mid descending colon(n=2)and sigmoid colon(n=2)prior to recording.As a result these data represent combined manometry and scintigraphy from the ascending colon in n=6and from the transverse colon in n=4.Propagating sequences:distribution,frequency and amplitudeIn all,585min of combined manometric and isotopic ﬂow data were collated across the mid-ascending colon and273min across the mid-transverse colon.Ante-grade PSs were recorded in each of the colonic regions, with96originating at or proximal to the mid-ascending colon and41PSs originating from a site proximal to the mid-transverse colon and extending up to or through the mid-transverse colon.Of the41PSs which extended through the mid-transverse colon,17had their site of origin in the cecum,the remaining24had their site of origin at or distal to the hepaticﬂexure. There were no HAPSs detected during the recording time.In comparison to antegrade PSs,retrograde PSs were signiﬁcantly less prevalent(P<0.0001)(Table1). Eight low amplitude antegrade PS were identiﬁed with a site of origin proximal to the mid-ascending colon and four with a site of origin distal to the mid-ascending colon and proximal to the mid-transverse colon(Table1).Five low amplitude retrograde PSs were identiﬁed,with three distal to the mid-ascending and two distal to the mid-transverse colon. Propagating sequences:relationship toluminalﬂowOver93%of antegrade(Fig.3)and retrograde(Fig.4) PSs were temporally associated with the propulsion of luminal contents(Table1).There was no apparent difference in PS amplitude or velocity between those PS associated withﬂow and those that were not.The antegrade low amplitude PSs also displayed a strong temporal association with episodicﬂow(91.6%)(Fig.3) while only two ofﬁve(40%)low amplitude retrograde PS were temporally associated with retrogradeﬂow (Table1).Theﬂow-associated probability could be calculated for all of the regions in which a contingency table was constructed.Aﬂow associated probability of ‡95%was calculated inﬁve of the six subjects in the ascending colon and four of four subjects in the transverse colon,indicating a genuine association between PSs and episodicﬂow across both the mid-ascending and mid-transverse colon(Table2). Episodic luminalﬂow and association with propagating sequencesIn total292discrete episodes of antegradeﬂow and175 discrete episodes of retrogradeﬂow were detected.In the ascending colon episodes of antegradeﬂow travers-ing the mid-ascending colon(226episodes;37.6±16.5 episodes/subject)were more prevalent than retrogradeTable1Total number of propagatingsequences(PS)recorded from the sixvolunteers and their temporal associationwithﬂow.Cecal PS are associated withﬂow across the mid-ascending colonicand transverse colonic PSs are associatedwithﬂow across the mid-transversecolonRegion Polarity Numberof PSsAssociatedwithﬂowAscending PS PSs Antegrade9689(93%)Retrograde1514(93%)Low amplitude PSs Antegrade88(100%)Retrograde32(67%)Transverse PS PSs Antegrade4138(93%)Retrograde99(100%)Low amplitude PSs Antegrade43(75%)Retrograde20P.G.Dinning et al.Neurogastroenterology and MotilityÓ2008The AuthorsJournal compilationÓ2008Blackwell Publishing Ltd516ﬂow (127episodes;21.2±7.3episodes/subject)(P <0.0001).In the transverse colon antegrade ﬂow(66episodes;16.5±5.2episodes/subject)and retro-grade ﬂow (48episodes;12.0±5.1episodes/subject)were equally prevalent.For the 273min in which isotope was present inboth the ascending and transverse colon,nearly half(43.5%)of antegrade ﬂow episodes that crossed themid-ascending colon continued beyond the mid-trans-verse colon.Indeed the majority (66%)of ﬂow episodesthat crossed the mid-transverse colon originated in theproximal ascending colon.The remaining episodes of ﬂow originating in the proximal ascending colon terminated at the hepatic ﬂexure.Of the 292episodes of antegrade ﬂow,45%were temporally associated with PSs.The degree of associ-ation between ﬂow and PSs varied considerably amongst colonic regions [ascending colon 41.6%vs 60.6%transverse colon;(P =0.006)]and amongst sub-jects (range:8%to 91%).Of the 175episodes of retrograde ﬂow only 10.8%were associated with retrograde PSs.Just under half (49%)of theretrograde Figure 3Temporal association between propagating sequences and ﬂow in the proximal colon.The hatched arrows link theindividual scintiscan image corresponding to the time along the horizontal axis at which acquisition of the frame was completed.Each solid arrow indicates the location of the manometric sidehole from which the corresponding pressure trace was recorded.The solid bars indicate episodes of ﬂow across the mid-ascending colon and mid-transverse colon.The ﬁrst cecal propagating sequence (PS1)contains individual propagating pressure waves with a trough to peak amplitude <5mmHg.The corresponding scintigraphic images clearly show content moving from the cecum to the hepatic ﬂexure.The second propagating sequence (PS2)originates in the cecum and propagates throughout the proximal colon.It was temporally linked with ﬂow across both the mid-ascending and mid-transversecolon.Figure 4An example of a retrograde propagating sequence temporarily associated with retrograde ﬂow across the mid-transverse colon.The hatched arrows link the individual scintiscan image corresponding to the time along the horizontal axis at which acquisition of the frame was completed.Each solid arrows indicates the location of the manometric sidehole from which the corresponding pressure trace was recorded.The solid bar represents the ﬂow period across the mid-point of the transverse colon.Volume 20,Number 5,May 2008Determinants of colonic ﬂow Ó2008The AuthorsJournal compilation Ó2008Blackwell Publishing Ltd 517ﬂow episodes were recorded immediately following episodes of antegradeﬂow.DISCUSSIONThis study has shown that the vast majority of proximal colonic PSs,regardless of site of origin, amplitude or polarity,are temporally linked to luminal propulsion.These data are in contrast to the only previously study which has attempted to detail the relationship between proximal colonic PSs and luminal ﬂow.1In that study only30%of antegrade PSs and less than10%of retrograde PSs originating distal to hepatic ﬂexure were deemed propulsive.In addition that study showed a correlation between propulsion and the amplitude of PSs.The difference in the reported ﬁndings between that study and ours can be explained by our use of high resolution scintigraphy and our development of a quantitative technique for analyzing the data.20In human colonic studies of combined manometry and scintigraphy,motor patters are recorded in real time while the image capture is limited by the frame rate of the scintiscanning equipment.As the majority of colonic propulsive events are thought to involve subtle movements of colonic content over short distances,26–28the larger the time window between captured scintigraphic images the more likely is the chance of overlooking these subtle movements.The scintigraphic frame rates used in the majority of previous human studies,have ranged from successive 1min frames5,7,29to1min frames every5min.6Such frame rates would limit detailed correlation between motor patterns andﬂow.Even when the image capture rate is improved to1 frame every15s two-thirds of the identiﬁed PSs were not associated with any detectable movement of isotope.1The incomplete correlation described in that study might be explained by that studyÕs reliance upon visual identiﬁcation of individual isotopic movements. Such analysis can be problematic because it is difﬁcult to pick up discreet movements over short distances, especially if image quality is poor.Visual analysis is more likely to detect high volume movements over large distances.To overcome problems associated with visual detec-tion ofﬂow we designed a quantitative technique to identify discrete,episodic movements of colonic con-tent on a moment-to-moment basis.20This quantita-tive technique increased our ability to detectﬂow when compared to visual analysis and therefore allowed us for theﬁrst time to examine in detail the propulsive nature of all PSs,including those with low amplitude pressure ing this technique we have shown that PSs are a major determinant of luminalﬂow.Thisﬁnding allows us to readdress previously conceived hypotheses regarding the physi-ology of the colon.For example Cook et al.1had described the relative propulsiveÔinefﬁciencyÕof ante-grade PS which was hypothesized to help retard antegrade transit,thus allowing time for optimal water and electrolyte absorption and reduce the challenge to continence.As our data indicates that PSs are propulsive,other factors are likely play a role in slowing antegrade transit.We propose that these factors include;(i)short extent PSs with component pressure waves between 2mmHg and40mmHg,(previously shown to make up the vast majority of PSs recorded in the human the proximal colon9,30);(ii)retrograde PSs;and(iii)the reﬂux of50%of the aboral proximal colonic bolus movement.Together,these factors are likely to con-tribute to the subtleÔto and froÕmotion helping to maintain maximal absorption and retard transit and stool frequency.Despite the propulsive properties of PSs,just over half of the identiﬁedﬂow episodes occurred in the absence of any identiﬁable PSs.While other factors are also attributed to propulsion of colonic content such as the tone of colon wall4,31and the viscosity of faecal material,27it is also likely that colonic manometry, will fail to detect a proportion of the colonic activity. Manometry is less sensitive when the diameter of the gut exceeds5.6cm14and as the cecum is the most capacious of the proximal colonic regions,it may explain why the degree of association betweenﬂow and PSs was signiﬁcantly reduced in the ascending compared to the transverse colon.In addition it has been reported that manometric pressure patterns can extend over relatively limitedTable2In each patient for each region the X2relation was greater than the X1relation allowing for calculation of the ﬂow associated probability.A value<95%indicates that any association between propagating sequences andﬂow could occur by chance.A value>95%indicates that there is a gen-uine association between propagating sequences andﬂowSubject Ascendingcolon(%)Transversecolon(%)196NA299.7NA39399.7499.9999.99599.9999.7699.9999.3P.G.Dinning et al.Neurogastroenterology and MotilityÓ2008The AuthorsJournal compilationÓ2008Blackwell Publishing Ltd518。

High-gain, polarization-preserving, Yb-doped fiber

High-gain,polarization-preserving,Yb-dopedﬁberampliﬁer for low-duty-cycle pulse ampliﬁcationJ.R.Marciante and J.D.ZuegelAmpliﬁed spontaneous emission(ASE)suppression techniques were utilized to fabricate a double-pass,Yb-doped ampliﬁer with the noise properties of a single-pass ampliﬁer.Simulations based on a rateequation model were used to analyze the ASE and the effectiveness of the suppression techniques.Thesetechniques were implemented in an alignment-free,double-pass,Yb-dopedﬁber ampliﬁer with a26dBgain at a wavelength23nm off the gain peak and aϪ48dB noiseﬂoor while amplifying linearly polarizedoptical pulses with a low-duty cycle.©2006Optical Society of AmericaOCIS codes:060.2320,140.3280,060.2340,060.2420,140.3510,140.4480.1.IntroductionEr-dopedﬁber ampliﬁers have become commonplace in telecommunications systems.1High-bit-rate pulse trains mean that continuous pumping can be utilized. Additionally,the unknown polarization state of the arriving pulses is ideal for commonﬁber-optic com-ponents and Er-dopedﬁbers,which typically do not preserve the polarization state of the light passing through them.For other applications,however,such conditions do not apply.Low-duty-cycle pulses leave gain available in theﬁber for long durations between pulses,which can lead to parasitic lasing or destructive self-pulsations.The ampliﬁcation of signals with wave-lengths far from the gain peak only enhances this prob-lem,since the gain can be substantially lower for such signals.Additionally,the ampliﬁcation of linear polar-izations requires not only a polarization-maintaining (PM)activeﬁber but also PM wavelength-division multiplexers(WDMs)and otherﬁber components that can be difﬁcult to fabricate.Utilizing a double-pass conﬁguration allows for sig-niﬁcantly higher gains to be obtained in a single-ﬁber ampliﬁer than can be achieved in a single pass.2–6 Additionally,using a Faraday rotator just before the end mirror ensures that the pulse returning from the second pass through the cavity has a polarization state that is orthogonal to that of the input pulse. Thus when used in conjunction with a polarizing beam splitter,the output pulse can be separated from the input pulse with highﬁdelity.3Double-pass con-ﬁgurations are ripe for parasitic lasing or destructive self-pulsations in a highly pumped unsaturated am-pliﬁer,however,since half a resonator is created in-tentionally.Special care must be taken to minimize reﬂections from components,connectors,and splices. Utilizing a timed gate,e.g.,an acousto-optic modula-tor(AOM),at the end of theﬁrst pass can ensure stable operation3but signiﬁcantly adds to the com-plexity of the system.In this work,a double-pass,Yb-dopedﬁber ampli-ﬁer is presented that overcomes these hurdles to pro-vide high gain for low-duty-cycle pulse repetition rates while preserving the linear polarization state in a single-spatial-mode package that requires no align-ment.In Section2,the ampliﬁed spontaneous emis-sion(ASE)is modeled in Yb-dopedﬁber ampliﬁers.In particular,the effects of ASEﬁltering are studied for use in a double-pass ampliﬁer conﬁguration.In Sec-tion3,results are presented on the measurements of a double-passﬁber ampliﬁer built with the various ASE-suppression schemes described in Section2.Ad-ditional discussions regarding the experimental con-ﬁguration,modeling,noise,and nonlinear effects are given in Section4,along with concluding remarks.2.Ampliﬁed Spontaneous Emission Considerations The ASE ofﬁber ampliﬁers can be studied via rate-equation modeling.7Such a model represents the op-tical power resolved in wavelength along the length of theﬁber and the Yb atomic states as a homoge-The authors are with the Laboratory for Laser Energetics, University of Rochester,250East River Road,Rochester,New York 14623-1299.J.Marciante’s e-mail address is johnm@lle.rochester. edu.Received19January2006;revised21April2006;accepted24 April2006;posted24April2006(Doc.ID67379).0003-6935/06/266798-07$15.00/0©2006Optical Society of America6798APPLIED OPTICS͞Vol.45,No.26͞10September2006neously broadened inversion.The resultant equa-tions are given byϮѨPϮѨzϩ1v gѨPϮѨtϭ⌫͓␴e N2Ϫ␴a N1͔PϮϪ␣PϮϩ2␴e N2hc␭3⌬␭ϩS␣RS Pϯ,(1)ѨN2Ѩtϭ1͵⌫͓␴e N2Ϫ␴a N1͔ϫ͑PϩϩPϪ͒d␭ϪN2␶,(2)where PϮ͑z,t,␭͒is the forward͑ϩ͒or backward͑Ϫ͒propagating power as a function of wavelength,time, and axial position along theﬁber.N2and N1are the upper and lower state population densities,respec-tively,as a function of time and axial position along the ﬁber and are related by the total ion concentration as N tϭN2ϩN1,which is constant throughout theﬁber. Wavelength-dependent parameters in Eqs.(1)and (2)include the geometrical overlap of theﬁber mode with the core⌫,the modal area A,the absorption͞emission cross section of the active ion␴a͞e,the group velocity v g,theﬁber attenuation␣,and the Rayleigh scattering coefﬁcient␣RS.Additional parameters in-clude the upper state lifetime␶,theﬁber-core capture coefﬁcient S,and the optical sampling bandwidth⌬␭. Equation(1)represents the bidirectional power ﬂow through theﬁber including stimulated emission, spontaneous emission,and absorption from the ac-tive ions;loss due to the inherentﬁber attenuation; and Rayleigh scattering.Since the parameters all have wavelength dependence,only a single equation is mathematically required to represent the behavior of the pump,the signal,and the ASE.Equation(2)represents the excited-state popula-tion density,which is governed by the absorption and emission of optical power as well as nonradiative decay.One notable omission in Eq.(2)is the wave-length dependence of the excited state governed by the details of the atomic transition manifold.This leads to,for example,excitation due to the absorption of long-wavelength light that can then be used to amplify shorter-wavelength light.While this effect issmall in the presence of a highly invertedﬁber,theimpact on the current work is to overestimate theASE at the gain peak.Since the current goal is tosuppress this feature,the model will yield a worsecase than is expected experimentally.For simplicity,the wavelength dependences ofA,v g,␣,and␣RS are neglected.Since the currentwork considers core-pumped(as opposed to cladding-pumped)activeﬁbers,⌫can also be well approxi-mated by a constant.The Yb cross sections areobtained from the data in Ref.8.For convenience,these cross sections areﬁt to a series of Gaussians of the form␴jϭ͚m A j,m exp͕Ϫ͓͑␭Ϫ␭j,m͒͞w j,m͔2͖with the coefﬁcients listed in Table1.Other parametersutilized are listed in Table2.Data provided with the Yb-dopedﬁber(Nufern),along with our own measurements on theﬁber,de-termined the values of N t,⌫,and A.The other valueswere obtained from Ref.7.The parameters usedare compiled in Table2.A simpleﬁnite-differencemethod is utilized to calculate the power and inver-sion distributions in theﬁber.Initial conditions as-sume no optical power or inversion within theﬁber.The pump power is included as a boundary condition.A double-pass conﬁguration can also be realized byapplying the appropriate boundary conditions.Unsaturatedﬁber ampliﬁers cannot be pumped toarbitrarily high levels because of self-pulsations andoscillation,which limit the length ofﬁber that can bepractically used in a single-pass ampliﬁer.In an un-saturated ampliﬁer,this translates to limited avail-able gain.Figure1shows the forward and reverseampliﬁed spontaneous emission for the case of re-verse pumping and very weak signal ampliﬁcation(no gain depletion)for a3.5m length of Yb:ﬁber withthe characteristics in Table2.Also shown in thisﬁgure are the small-signal gain,deﬁned as the ratioof output energy to input energy,for a1053nm signaland the pump leakage.After140mW of pump power,theﬁber is almost completely inverted,and the re-maining pump is lost out of the opposite end of theﬁber.The small-signal gain of23nm off the gain peakis therefore limited to approximately20dB.Since the gain is in fact unsaturated,simply sendingthe signal back through for a second pass increasesthe ampliﬁcation without additional pumping.Such aTable1.Gaussian Coefﬁcients for Yb Emission and AbsorptionCross SectionsjA j,m(10Ϫ27m2)␭j,m(nm)wj,m(nm)a18095070 a36089524 a51091822 a16097112 a,e23259754 e16097812 e340102520 e175105060 e150103090Table2.Parameters Used in SimulationsParameter ValueNt9.4ϫ1024mϪ3⌫0.85A30␮m2vgc͞1.5␣0.003mϪ1S␣RS1.2ϫ10Ϫ7mϪ1␶0.84ms⌬␭1nm␭pump976nm␭signal1053nm10September2006͞Vol.45,No.26͞APPLIED OPTICS6799double-pass conﬁguration,however,also allows the ASE to make a second trip through the gain,which can lead to undesirable oscillation and self-pulsations. Therefore the ASE must beﬁltered to use a double-pass conﬁguration.Two simple methods ofﬁltration are investigated,as depicted in Fig.2.Theﬁrst is a bandpassﬁlter,which is inserted between subsequent trips through the activeﬁber to deny double-pass ASE except in a small bandwidth around theﬁlter peak. The second is a WDM designed to split the ASE peak from the signal,which removes a signiﬁcant fraction of the ASE power from the signal,provided the signal is not near the gain peak.Four different ampliﬁer con-ﬁgurations are modeled,as shown in Fig.2.Theﬁrst two are simple single-and double-pass conﬁgurations through theﬁber.In the third conﬁguration,a band-passﬁlter is added between subsequent passes through theﬁber.The fourth conﬁguration adds a WDMﬁlter to the output of the third conﬁguration. For simplicity,theﬁlters are assumed to be lossless at the transmission peaks with zero transmission at the nulls.The mirror adds1dB of loss to the double-pass ampliﬁers.Assuming pump and signal wave-lengths of976and1053nm,respectively,the total (spectrally integrated)ASE power out of the different ampliﬁer conﬁgurations is shown in Fig.3as a func-tion of pump power.Because of undepleted gain and pump leakage,the single-pass ASE has a maximum power below6mW.In the double-pass conﬁguration, the ampliﬁer becomes saturated by the ASE,which extracts a signiﬁcant fraction of the gain in theﬁber. This linear trend in the ASE growth with pump powerto an ASE level that is greater than25times thecase and means that there will be veryreduced gain available for the signal.In con-the dotted trace shows that the insertion of thebandpassﬁlter prohibits the ASE closest to the gainpeak from experiencing double-pass gain.The totalASE is therefore limited to small-signal ampliﬁcation,even with double-pass ampliﬁcation far off the gainpeak,and accumulates no more than twice the powerof the single-pass conﬁguration.The insertion of thisﬁlter then allows for exponential signal gain from thedouble-pass ampliﬁer.The addition of the WDMﬁlter(solid curve)reduces the total ASE output power ofthe double-passﬁber ampliﬁer to only30%more thanthe single-pass ASE.The ASE spectra for the four conﬁgurations areshown in Fig.4at a pump power of250mW.The ASE Fig.1.Total(spectrally integrated)forward(solid curve)andreverse(dashed curve)ASE,976nm pump leakage,and1053nmsmall-signal gain as a function of pump power for a3.5m length ofYb:ﬁber.Fig.2.Depiction of modeled conﬁgurations:(a)single pass,(b)double pass,(c)double pass with an intracavity bandpassﬁlter,and(d)same as(c)with a WDMﬁlter at the ampliﬁer output.Fig.3.Total(spectrally integrated)ASE power at the ampliﬁeroutput as a function of pump power for the conﬁgurations shown inFig.2using theﬁber from Fig.1.6800APPLIED OPTICS͞Vol.45,No.26͞10September2006within the bandpass ﬁlter is actually stronger thanunﬁltered double-pass ASE since the gain is un-Nonetheless,this lack of gain saturation for double-pass gain of the signal in the am-The bandpass ﬁlter is therefore critical for the operation of this double-pass conﬁguration for the ampliﬁcation of signals off the gain peak.3.Experimental ResultsUnder the guidance of Section 2,a double-pass polar-ized ampliﬁer was constructed containing both the bandpass ﬁlter and the WDM,utilizing a Faraday mirror with a polarizing beam splitter (PBS)to sep-arate input from output and preserve the linear polarization state.This ampliﬁer conﬁguration is shown in Fig.5and utilizes both single-mode (SM)and PM ﬁbers.The input signal comes through a PM-pigtailed isolator (Optics for Research)to prevent any ASE or signal from returning to the seed source.The light then passes through a PM-pigtailed polariz-ing beam splitter (OZ Optics)followed by a SM 1030nm ͞1053nm WDM (ITF)used to reduce ASE.A SM WDM (Lightel)combines the seed light with pump light from a ﬁber-Bragg-grating-stabilized pump laser (JDSU)with a second WDM in series for additional isolation of the pump diode from the am-pliﬁed signal.The combined light is sent into 3.6m of SM,single-clad,Yb-doped ﬁber (Nufern)with an un-saturated absorption coefﬁcient of approximately 70dB ͞m at 975nm.After the ﬁrst pass of ampliﬁca-tion,the signal passes through a Faraday mirror (Op-tics for Research),a factory-aligned,ﬁber-coupled package containing a Faraday rotator,a 10nm band-pass ﬁlter at 1053nm (Andover),and a mirror.The reﬂected light passes back through the Faraday mir-ror package,the Yb-doped ﬁber,and the WDMs,one of which acts to ﬁlter out the ASE centered at 1030nm (WDM1).Since the polarization at the PBS is orthogonal to that which entered the PBS because of the Faraday mirror,the light is ejected out of a different port and sent through a PM 90͞10splitter (Lightel)to provide polarized signal and sample ports.All ﬁbers were spliced using a Furukawa S183PM fusion splicer,and there are no alignment knobs in the system.The pump was operated contin-uously,and there is no AOM gate,so no temporal alignment is required between the seed pulses and the ampliﬁer.The seed pulse used in this ampliﬁer was a 2ns square pulse with 1.56pJ of energy,resulting in a peak power of 0.78mW.The seed pulse had an opti-cal wavelength of 1053nm and a pulse repetition rate of 300Hz and was linear polarized with a polariza-tion extinction ratio of 20dB.Different lengths of Yb-doped ﬁber were tested in the ampliﬁer to opti-mize the active ﬁber length in terms of maximizing gain while maintaining stability as well as operation free from parasitic lasing or self-pulsations.For a given ﬁber length,a fraction of the ﬁber remains unpumped,and thus lossy to the signal wavelength.If the pumped portion of the ﬁber has sufﬁcient gain,then the ampliﬁer can Q switch because of the satu-rable absorption of the unpumped section of ﬁber andFig.4.Ampliﬁed spontaneous emission spectra at the ampliﬁer output for the conﬁgurations shown in Fig.2using the ﬁber from Fig.1with 250mW of pump power.Fig.5.Schematic of a high-gain double-pass ampliﬁer consisting of input and output isolators,a PBS,an ASE–signal wavelength division multiplexer (WDM1),two pump–signal wavelength division multiplexers (WDM2),3.6m of Yb-doped ﬁber,a Faraday mirror,and a 90͞10splitter.The Faraday mirror was a factory-aligned package containing a lens (L),a Faraday rotator (FR),a bandpass ﬁlter (F),and a mirror (M).The PM ﬁber is notated by dotted curves,while the SM ﬁber is notated by solid curves.10September 2006͞Vol.45,No.26͞APPLIED OPTICS6801minute reﬂections in the system.This can be reme-died by making the ﬁber sufﬁciently short;however,there is an optimum ﬁber length for which the ﬁber provides maximum gain without self-pulsations.For several ampliﬁers that were constructed,the opti-mum ﬁber length was determined to be near 3.5m,regardless of the variability between components or splice quality.The pump utilized had a threshold of 16mA and a slope efﬁciency of 0.68mW ͞mA.Figure 6shows the signal gain,output energy,and total ASE power as a function of pump current.As the pump current is increased beyond 200mA,the am-pliﬁer gain rolls off since the additional pump light is mostly not absorbed in the active ﬁber,a feature that is also reﬂected in the ASE curve.It is important to note that because of the low seed energy and repetition rate,the ampliﬁer is unsaturated.Thus the small-signal gain afforded by this ampliﬁer 23nm off the gain peak is nearly 27dB.Self-pulsations were not observed at any pump cur-rents because of the bandpass ﬁlter in the Faraday mirror assembly and the 1030nm ͞1053nm WDM that suppresses the stronger gain at shorter wave-lengths.Figure 7shows the ASE spectra of the double-pass ampliﬁer for various pump current levels.The seed wavelength is depicted by the vertical dashed curve.The traces clearly show the double-pass gain of the wavelengths in the ﬁlter passband compared to the single-pass gain of those outside the passband.The top trace in Fig.7,which is offset for clarity,is the ASE spectra for the double-pass ampliﬁer without the 1030nm ͞1053nm WDM.This WDM,combined with the 10nm bandpass ﬁlter,has a signiﬁcant impact both on the output of the ampliﬁer as well as the stability against lasing and self-pulsations,as evi-denced in Fig.7,and shows results very similar to the modeling results shown in Fig.4.It is difﬁcult to deﬁne the noise ﬂoor of a system with regard to a low-repetition-rate signal.Simply comparing the strength of the signals on an optical spectrum analyzer requires an optical gate such that the spectrum is only integrated for the duration of the pulse.One alternative method compares the peak power of the ampliﬁed signal to the ASE power.Amore meaningful metric that more accurately repre-sents an optical signal-to-noise ﬁgure of merit com-pares the peak power of the ampliﬁed pulse to the ASE power in a limited spectral bandwidth around the seed-pulse wavelength.While the total noise ﬂoor is less than Ϫ28dB across the entire operating range,the bandwidth-limited noise ﬂoor is better than Ϫ48dB in a 0.1nm bandwidth around the signal wavelength.Since the ampliﬁer runs unsaturated,the noise ﬂoor is essentially constant as a function of the pump current.The combination of a Faraday mirror and PBS al-lows for high-ﬁdelity separation of the input and out-put signals at the front end of the ampliﬁer while maintaining the linear polarization state of the seed.The polarization extinction of the ampliﬁed signal was measured to be 19.9dB,which is identical to that of the input signal.4.Discussion and ConclusionsThe pump is a grating-stabilized diode centered at 975.5nm.The feedback from the ﬁber Bragg grating maintains stable laser operation even in the presence of optical feedback,which can otherwise destabilize a diode laser.9However,the ampliﬁed seed can be a problem in damaging the diode.Starting with a 2pJ seed signal of 2ns duration,the ampliﬁed signal be-comes ϳ1nJ.By some spurious reﬂection,a second round trip through the double-pass ampliﬁer is pos-sible,leading to 0.5␮J.Even in the presence of a pump–signal WDM,the fraction split off from this energetic pulse ͑ϳ15dB ͒leads to a pulse impinging on the face of the pump diode with an energy of 15nJ and a peak power over 7W.This can cause cata-strophic optical damage on the facet of the laser di-ode.Two components in our system serve to eliminate this problem.The ﬁrst is the output isolator,which signiﬁcantly reduces the risk of a high-energy back-reﬂection into the ampliﬁer.The second is thesecondFig.7.Ampliﬁed spontaneous emission spectra from a dual-pass ﬁber ampliﬁer for various pumping levels.Also shown are the seed wavelength at 1053nm and the ASE trace for the ampliﬁer with-out the 1030nm ͞1053nm WDM,which has been offset forclarity.Fig.6.Gain,output energy,and ASE power of the experimental ampliﬁer described in Fig.5as a function of pump current.6802APPLIED OPTICS ͞Vol.45,No.26͞10September 2006pump–signal WDM,which serves as anϳ15dB iso-lator of the signal pulse into the diode.The agreement between measurements and simu-lations is favorable in the prediction of the noise char-acteristics of the ampliﬁer,as shown in Table3.In particular,using the ratio of small-signal gain over ASE power leads to an ampliﬁer performance metric of1161͞mW,which agrees exceedingly well with the measurements.Both the signal gain and the ASE power levels were approximately6dB too high in the simulations,even when accounting for realistic component loss.There are several reasonable expla-nations for the discrepancy.First,there is the uncer-tainty in the loss owing to the components and the splices.Second,the addition of the10nmﬁlter in the Faraday mirror assembly may cause additional in-sertion loss due to slight perturbations in propaga-tion length and͞or angle between the mirror and the ﬁber within the assembly.Finally,some of the parameters used in the simulations were simply taken from previous work.7,8In particular,the emis-sion and absorption cross sections can play a large role in determining the output performance of the ampliﬁer.By varying the simulated emission cross section at1053nm,it is found that the ASE and gain change by9.5%and8.1%,respectively,for a1% change in the emission cross section alone.Given the variability between measurements of Yb absorption and emission cross sections,8,10this is likely a strong contributor to the mismatch in absolute values of gain and ASE power.The unpumped ampliﬁer has a passive loss of approximately15dB.The simulations show an un-pumped ampliﬁer loss of13.9dB.While some of this loss is due to absorption in the unpumped Yb-doped ﬁber,almost9dB of this loss is insertion loss of the constituent components.Many of these components are free-space optics that are packaged withﬁber pigtails at the vendor.All-ﬁber components would certainly help to increase the gain of the system,as well as the noiseﬁgure.The noiseﬁgure of the am-pliﬁer is given by11NFϭ2P ASEh␯⌬␯opt G,(3)where P ASE is the ASE power measured on a band-width⌬␯opt,G is the signal gain,and␯is the optical frequency of the ing measured parameters, the noiseﬁgure of the double-pass ampliﬁer in a 0.1nm bandwidth is6.6dB.Considering that the seed is degraded by2.8dB because of the insertion loss of the components before the activeﬁber,this result leads us to conclude that,in spite of operating far from the gain peak in a double-pass conﬁguration, the ampliﬁer is of extremely high quality because of the ASE suppression techniques utilized.Further, our model shows that our double-pass ampliﬁer does not add any penalty to the noiseﬁgure,as has been observed in Er-doped ampliﬁers used in a simple double-pass conﬁguration.4Multiple path interference(MPI)can also lead to a degradation of the signal-to-noise ratio inﬁber ampliﬁers.12–14In conventional single-pass ampliﬁ-ers,Rayleigh scattering can reﬂect a portion of the signal backward.A second Rayleigh event can sub-sequently reﬂect that portion back into the signal path.This effect is particularly important when the scattering occurs at locations that allow the scattered photons to see additional gain,as compared to the signal gain in the ampliﬁer.For double-pass ampli-ﬁers,the more signiﬁcant contribution comes from a single Rayleigh scattering event that occurs in the return trip through the ampliﬁer.This backscattered light will see additional gain and a deterministic sec-ond reﬂection(via the mirror)back through the am-pliﬁer into the signal path.The strength of the double Rayleigh scattering(DRS)compared to the signal is generally given by15P DRS͑L͒S͑͒ϭ͵0L d z2͵0z2d z1͑S␣RS͒2Gជ͑z1,z2͒Gឈ͑z1,z2͒,(4)where the G terms represent the gain in the for-ward and reverse directions.In applying this for-malism to our double-pass case,one of the Rayleigh scattering terms,S␣RS,is replaced by a determinis-tic reﬂection from the back end of the double-pass ampliﬁer,R2␦͑z2ϪL͞2͒,where R2is the power re-ﬂection coefﬁcient of the ampliﬁer end mirror.The highest gain case is where the signal has completed its trip through the gainﬁber and the scattered light then sees a complete additional double pass through the gainﬁber.This can be formally written for our unsaturated ampliﬁer asP DRS͑L͒P S͑L͒ϭR2S␣RS͵L͞2Ld z2e g͑z2ϪL͞2͒ϭR2S␣RS2g͑G DPϪͱG DP͒,(5)where G DP is the double-pass ampliﬁer gain.For the ampliﬁer described in Section3,the resultant rela-tive noise strength due to MPI isϪ47dB.It is important to note,however,that for low-duty-cycle pulse-train ampliﬁcation,this MPI is temporally sep-arable from the desired signal pulse and can there-fore be eliminated by temporal gating.Consideringparison of Measured and Simulated Values for theDouble-Pass Fiber AmpliﬁerCharacteristic Measured Value Simulation ResultSmall-signal gain͞ASE1175͞mW1161͞mWTotal noiseﬂoorϪ28dBϪ30.6dBNoiseﬂoor in0.1nmbandwidthϪ48dBϪ43.5dBSmall-signal gain26.6dB32.3dB10September2006͞Vol.45,No.26͞APPLIED OPTICS6803only MPI noise that contributes during the signal implies signiﬁcantly shorter gain paths for the MPI photons.This effect will,therefore,be more pro-nounced at the trailing edge of the pulse.The gain length of the backscattered light is conﬁned to half the pulse duration.This is simply represented in Eq.(5)by substituting the gainﬁber length L with␶v g͞2, where␶is the pulse duration.For a2ns pulse,the relative noise is,therefore,Ϫ80dB on the back end of the pulse.From these calculations,it is evident that MPI will not present a signiﬁcant impairment,par-ticularly if temporalﬁltering is utilized.Finally,nonlinear effects in this ampliﬁer need to be considered to understand the scaling to high output energy.For narrowband signals,stimulated Brillouin scattering(SBS)is generally the dominant limitation.In the application of low-duty-cycle pulse trains where only one pulse exists in the ampliﬁer at any given time,however,the Brillouin gain only ex-ists during the pulse.Since SBS produces light that propagates backward with respect to the signal,the effectiveﬁber length is limited to␶v g͞2.The SBS gain threshold16for the6␮m coreﬁber is approximately 20W m,which leads to a peak power limitation of 100W or100nJ per nanosecond of pulse duration. Stimulated Raman scattering(SRS)has a higher threshold,but is not limited to the pulse duration since the photons are scattered in the forward direc-tion.For the case of exponential gain where the Raman pump changes during propagation,an effec-tive length of the SRS effect can be calculated,similar to what is done for pump loss in conventional Raman ampliﬁers.16For the ampliﬁer described in Fig.5, however,theﬁber length of interest is the span from the output end of the Yb-dopedﬁber to the output of the ampliﬁer(approximately3m),during which the signal strength(Raman pump)is at its highest level and is effectively constant.Given that the SRS thresh-old16is approximately500W m,this leads to a limi-tation of166W of peak power,or166nJ͞ns of pulse duration.For2ns pulses,energies below1nJ were reported in Section3,indicating that nonlinear ef-fects were not important for the performance of the ampliﬁer.However,scaling the pulse energy by a factor of100is possible before running into nonlinear limitations in this ampliﬁer.In conclusion,ampliﬁed spontaneous emission sup-pression techniques were utilized to fabricate a double-pass,Yb-doped ampliﬁer with the noise properties of a single-pass ampliﬁer.Simulations based on a rate-equation model were used to analyze the ASE and the impact of the suppression techniques.These tech-niques were implemented in an alignment-free,double-pass,Yb-dopedﬁber ampliﬁer with a26dB gain at a wavelength23nm off the gain peak and aϪ48dB noiseﬂoor while amplifying linearly polarized optical pulses with a low-duty cycle.The authors thank Jake Bromage for technical discussions.This work was supported by the U.S. Department of Energy(DOE)Ofﬁce of Inertial Con-ﬁnement Fusion under Cooperative Agreement DE-FC52-92SF19460,the University of Rochester,and the New York State Energy Research and Develop-ment Authority.The support of the DOE does not constitute an endorsement by the DOE of the views expressed in this paper.References1.E.Desurvire,Erbium-Doped Fiber Ampliﬁers:Principles andApplications(Wiley,1994).2.S.Hwang,K.W.Song,H.J.Kwon,J.Koh,Y.J.Oh,and K.Cho,“Broad-band erbium-dopedﬁber ampliﬁer with double-pass conﬁguration,”IEEE Photon.Technol.Lett.13,1289–1291(2001).3.A.Galvanauskas,G.C.Cho,A.Hariharan,M.E.Fermann,and D.Harter,“Generation of high-energy femtosecond pulses in multimode-core Yb-ﬁber chirped-pulse ampliﬁcation sys-tems,”Opt.Lett.26,935–937(2001).4.S.W.Harun,P.Poopalan,and H.Ahmad,“Gain enhancementin L-band EDFA through a double-pass technique,”IEEE Photon.Technol.Lett.14,296–297(2002).5.M.Tang,Y.D.Gong,and P.Shum,“Dynamic properties ofdouble-pass discrete Raman ampliﬁer with FBG-based all-optical gain clamping techniques,”IEEE Photon.Technol.Lett.16,768–770(2004).6.L.L.Yi,L.Zhan,J.H.Ji,Q.H.Ye,and Y.X.Xia,“Improve-ment of gain and noiseﬁgure in double-pass L-band EDFA by incorporating aﬁber Bragg grating,”IEEE Photon.Technol.Lett.16,1005–1007(2004).7.Y.Wang and H.Po,“Dynamic characteristics of double-cladﬁber ampliﬁers for high-power pulse ampliﬁcation,”J.Light-wave Technol.21,2262–2270(2003).8.R.Paschotta,J.Nilsson,A.C.Tropper,and D.C.Hanna,“Ytterbium-dopedﬁber ampliﬁers,”IEEE J.Quantum Elec-tron.33,1049–1056(1997).ach and A.R.Chraplyvy,“Regimes of feedback effectsin1.5-␮m distributed feedback lasers,”J.Lightwave Technol.LT-4,1655–1661(1986).10.N.A.Brilliant,R.J.Beach,A.D.Drobshoff,and S.A.Payne,“Narrow-line ytterbiumﬁber master-oscillator power ampli-ﬁer,”J.Opt.Soc.Am.B19,981–991(2002).11.P.C.Becker,N.A.Olsson,and J.R.Simpson,Erbium-DopedFiber Ampliﬁers:Fundamentals and Technology(Academic, 1999).12.S.Faralli and F.Di Pasquale,“Impact of double Rayleighscattering noise in distributed higher order Raman pumping schemes,”IEEE Photon.Technol.Lett.15,804–806(2003).13.S.W.Harun,N.Tamchek,P.Poopalan,and H.Ahmad,“Double-pass L-band EDFA with enhanced noiseﬁgure char-acteristics,”IEEE Photon.Technol.Lett.15,1055–1057 (2003).14.M.Tang,P.Shum,and Y.D.Gong,“Design of double-passdiscrete Raman ampliﬁer and the impairments induced by Rayleigh backscattering,”Opt.Express11,1887–1893(2003).15.J.Bromage,P.J.Winzer,and R.-J.Essiambre,“Multiple pathinterference and its impact on system design,”in Raman Am-pliﬁers for Telecommunications:2,Subsystems and Systems, M.N.Islam,ed.,Springer Series in Optical Science(Springer, 2004),Chap.15.16.G.P.Agrawal,Nonlinear Fiber Optics,2nd ed.,Optics andPhotonics Series(Academic,1995).6804APPLIED OPTICS͞Vol.45,No.26͞10September2006。

SY88149CL中文资料

SY88149CL3.3V, 1.25Gbps PECL Limiting PostAmplifier w/High Gain TTL Signal DetectGeneral DescriptionThe SY88149CL is a high-sensitivity limiting postamplifier designed for use in fiber-optic receivers. Thesedevices connect to typical transimpedance amplifiers(TIAs). The linear signal output from TIAs can containsignificant amounts of noise and may vary in amplitudeover time. The SY88149CL quantizes these signals andoutputs PECL level waveforms.The SY88149CL operates from a single +3.3V powersupply, over temperatures ranging from –40o C to +85o C.With its wide bandwidth and high gain, signals with datarates up to 1.25Gbps, and as small as 5mV pp, can beamplified to drive devices with PECL inputs.The SY88149CL generates a high-gain signal-detect(SD) open-collector TTL output. The SD function has ahigh gain input stage for increased sensitivity. Aprogrammable Signal Detect level set pin (SD LVL) setsthe sensitivity of the input amplitude detection. SDasserts high if the input amplitude rises above thethreshold set by SD LVL and de-asserts low otherwise.The enable input (EN) de-asserts the true output signalwithout removing the input signal. The SD output can befed back to the EN input to maintain output stabilityunder a loss-of-signal condition. Typically, 3.4dB SDhysteresis is provided to prevent chattering.All support documentation can be found on Micrel’s website at: .Features•Single 3.3V power supply•Fast SD enable/disable time•622Mbps to 1.25Gbps operation•Low-noise PECL data outputs• High-gain SD•Chatter-free Open-Collector TTL signal detect (SD)output with internal 4.75kΩ pull-up resistor•TTL EN input•Programmable SD level set (SD LVL)•Available in a tiny 10-pin MSOP packageApplications• GE-PON/GPON/EPON• Gigabit Ethernet• 1062Mbps Fibre Channel• OC-12/24 SONET/SDH•High-gain line driver and line receiver•Low-gain TIA interfaceMarkets• FTTH/FTTP• Datacom/Telecom• Optical transceiverTypical Application CircuitOrdering Information(1)Part Number PackageType OperatingRangePackage MarkingLead FinishSY88149CLKG K10-1 IndustrialSY88149CLwithPb-Free bar line indicator NiPdAu Pb-Free SY88149CLKGTR(1)K10-1 Industrial SY88149CL with Pb-Free bar line indicator NiPdAu Pb-Free Notes:1. Tape and Reel.Pin Configuration10-Pin MSOP (K10-1)Pin DescriptionPin Number Pin Name Type Pin Function1 ENTTL Input: Default isHIGH. Enable: This input enables the outputs when it is HIGH. Note that this input is internally connected to a 25kΩ pull-up resistor and will default to a logic HIGH state if left open.2 DIN Data Input True data input.3 /DIN Data Input Complementary data input.4 VREF Reference voltage: Placing a capacitor here to V CC helpsstabilize SD LVL.5 SDLVL Input Signal Detect Level Set: a resistor from this pin to V CC sets thethreshold for the data input amplitude at which SD will beasserted.6 GND GroundDeviceground.7 SDOpen-collector TTLoutput w/internal 4.75kΩpull-up resistor Signal-Detect asserts high when the data input amplitude rises above the threshold set by SD LVL.8 /DOUT PECL Output Complementary data output.9 DOUT PECL Output True data output.10 VCC Power Supply Positive power supply.Absolute Maximum Ratings(1)Supply Voltage (V CC).......................................0V to +7.0V Input Voltage (DIN, /DIN).......................................0 to V CC Output Current (I OUT)Continuous........................................................±50mA Surge..............................................................±100mA EN Voltage.............................................................0 to V CC V REF Current..........................................-800µA to +500µA SD LVL Voltage...................................................V REF to V CC Lead Temperature (soldering, 20sec.).....................260°C Storage Temperature (T s).......................–65°C to +150°C Operating Ratings(2)Supply Voltage (V CC).............................+3.0V to +3.6V Ambient Temperature (T A)...................–40°C to +85°C Junction Temperature (T J).................–40°C to +120°C Junction Thermal ResistanceMSOP(θJA) Still-air...................................113°C/WDC Electrical CharacteristicsV CC = 3.0 to 3.6V; R L = 50Ω to V CC-2V; T A = –40°C to +85°C, typical values at V CC = 3.3V, T A = 25°C.Symbol Parameter Condition Min Typ Max Units I CC Power Supply Current No output load 26 39 mASD LVL SD LVL Voltage V REF V CC V V OH PECL Output HIGH Voltage V CC-1.085 V CC-0.955 V CC-0.880VV OL PECL Output LOW Voltage V CC-1.830 V CC-1.705 V CC-1.555VV IHCMR Common Mode Range GND+2.0 V CC V V REF ReferenceVoltage V CC-1.48 V CC-1.32 V CC-1.16VTTL DC Electrical CharacteristicsV CC = 3.0 to 3.6V; R L = 50Ω to V CC-2V; T A = –40°C to +85°C, typical values at V CC = 3.3V, T A = 25°C.Symbol Parameter Condition Min Typ Max Units V IH EN Input HIGH Voltage 2.0 VV IL EN Input LOW Voltage 0.8 VI IH EN Input HIGH Current V IN = 2.7VV IN = V CC20 100µAµAI IL EN Input LOW Current V IN = 0.5V -0.3 mAV OH SD Output HIGH Level V CC > 3.3V, I OH-MAX < 160µAV CC < 3.3V, I OH-MAX < 160µA 2.42.0VVV OL SD Output LOW Level I OL = +2mA 0.5 V Notes:1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is notimplied at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.3. Thermal performance assumes the use of a 4-layer PCB. Exposed pad must be soldered (or equivalent) to the device’s most negative potentialon the PCB.AC Electrical CharacteristicsV CC = 3.0V to 3.6V; R LOAD = 50Ω to V CC–2V; T A = –40°C to +85°C.Symbol Parameter Condition MinTypMaxUnitst r, t f Output Rise/Fall Time(20% to 80%) Note 4 260pst JITTER DeterministicRandom Note 5Note 6155ps PPps RMSV ID Differential Input Voltage Swing Figure 1 5 1800 mV PPV OD Differential Output VoltageSwing V ID > 18mV PP Figure 11500mV PPT OFF SD Release Time 100 500 nsT ON SDAssertTime 100500ns SD AL Low SD Assert Level R SDLVL = 15kΩ, Note 8 3.4 mV PPSD DL Low SD De-assert Level R SDLVL = 15kΩ, Note 8 2.3 mV PPHYS L Low SD Hysteresis R SDLVL = 15kΩ, Note 7 3.4 dBSD AM Medium SD Assert Level R SDLVL = 5kΩ, Note 8 6.2 8 mV PPSD DM Medium SD De-assert Level R SDLVL = 5kΩ, Note 8 3 4.2 mV PPHYS M Medium SD Hysteresis R SDLVL = 5kΩ, Note 7 2 3.4 5 dBSD AH High SD Assert Level R SDLVL = 100Ω, Note 8 16.4 20 mV PPSD DH High SD De-assert Level R SDLVL = 100Ω, Note 8 8 10.8 mV PPHYS H High SD Hysteresis R SDLVL = 100Ω, Note 7 2 3.4 5 dBB-3dB 3dBBandwidth 1 GHz A V(Diff)Differential Voltage Gain 42 dBS21Single-ended Small-Signal Gain 36 dBNotes:4. Amplifier in limiting mode. Input is a 200MHz square wave.5. Deterministic jitter measured using 1.25Gbps K28.5 pattern, V ID = 10mV PP.6. Random jitter measured using 1.25Gbps K28.7 pattern, V ID = 10mV PP.7. This specification defines electrical hysteresis as 20log(SD Assert/SD De-assert). The ratio between optical hysteresis andelectrical hysteresis is found to vary between 1.5 and 2 depending upon the level of received optical power and ROSAcharacteristics. Based upon that ratio, the optical hysteresis corresponding to the electrical hysteresis range 2dB-5dB, shownin the AC characteristics table, will be 1dB-4dB optical Hysteresis.8. See “Typical Operating Characteristics” for a graph showing how to choose a particular R SDLVL for a particular SD assert andits associated de-assert amplitude.Typical Operating CharacteristicsV CC = 3.3V, T A = 25°C, R L = 50Ω to V CC–2V, unless otherwise stated.R SDLVL (kΩ) R SDLVL (kΩ)Functional Block DiagramDetailed DescriptionThe SY88149CL high-sensitivity limiting post amplifier operates from a single +3.3V power supply, over temperatures from –40°C to +85°C. Signals with data rates up to 1.25Gbps and as small as 5mV PP can be amplified. Figure 1 shows the allowed input voltage swing. The SY88149CL generates an SD output, allowing feedback to EN for output stability. SD LVL sets the sensitivity of the input amplitude detection.Input Amplifier/BufferFigure 2 shows a simplified schematic of the input stage. The high-sensitivity of the input amplifier allows signals as small as 5mV PP to be detected and amplified. The input amplifier allows input signals as large as 1800mV PP . Input signals are linearly amplified with a typically 42dB differential voltage gain. Since it is a limiting amplifier, the SY88149CL outputs typically 1500mV PP voltage-limited waveforms for input signals that are greater than 12mV PP . Applications requiring the SY88149CL to operate with high-gain should have the upstream TIA placed as close as possible to the SY88149CL’s input pins. This ensure the best performance of the device.Output BufferThe SY88149CL’s PECL output buffer is designed to drive 50Ω lines. The output buffer requires appropriate termination for proper operation. An external 50Ω resistor to V CC –2V for each output pin provides this. Figure 3 shows a simplified schematic of the output stage.Signal DetectThe SY88149CL generates a chatter-free Signal-Detect (SD) open-collector TTL output with internal 4.75k Ω pull-up resistor, as shown in Figure 4. SD is used to determine that the input amplitude is too small to be considered a valid input. SD asserts high if the input amplitude rises above threshold set by SDLVL and de-asserts low otherwise. SD can be fed back to the enable (EN) input to maintain output stability under a SDs of signal condition. EN de-asserts low the true output signal without removing the input signals. Typically, 3.4dB SD hysteresis is provided to prevent chattering.Signal Detect Level SetA programmable SD level set pin (SD LVL ) sets the threshold of the input amplitude detection. Connecting an external resistor between V CC and SD LVL sets the voltage at SD LVL . This voltage ranges from V CC to V REF . The external resistor creates a voltage divider between V CC and V REF , as shown in Figure 5.HysteresisThe SY88149CL provides typically 3.4dB SD electrical hysteresis. By definition, a power ratio measured in dB is 10log (power ratio). Power is calculated as V 2IN /R for an electrical signal. Hence the same ratio can be stated as 20log (voltage ratio). While in linear mode, the electrical voltage input changes linearly with the optical power and hence the ratios change linearly. Therefore, the optical hysteresis in dB is half the electrical hysteresis in dB given in the data sheet. The SY88149CL is an electrical device; this data sheet refers to hysteresis in electrical terms. With 3.4dB SD hysteresis, a voltage factor of 1.5 is required to assert or de-assert SD.Figure 1. VIS and VID DefinitionFigure 2. Input Structure Figure 3. Output StructureFigure 4. SD Output StructureFigure 5. SD LVL Setting CircuitNote: Recommended value for R SDLVL is 15kΩ or less.Related Product and Support DocumentationPart Number Function Data Sheet Link/product-info/sy88933al.shtmlSY88933AL 3.3V/5V 1.25Gbps PECL High-SensitivityLimiting Post Amplifier with TTL SD/product-info/app_hints+notes.shtml Application Notes Notes on Sensitivity and Hysteresis in MicrelPost AmplifiersPackage Information10-Pin MSOP (K10-1)。

普芦卡必利和莫沙必利分别联用小剂量聚乙二醇治疗老年难治性功能性便秘的短期疗效比较

普芦卡必利和莫沙必利分别联用小剂量聚乙二醇治疗老年难治性功能性便秘的短期疗效比较黄海辉;张小敏;赵亮【摘要】目的比较普芦卡必利、莫沙必利分别联用小剂量聚乙二醇治疗老年难治性功能性便秘的短期疗效.方法对2014年5月至2016年2月在该院门诊诊治的老年难治性功能性便秘患者90例进行回顾性分析.入选病例分为两组,每组45例.普芦卡必利组:琥珀酸普芦卡必利片,2 mg,每日1次;莫沙必利组:枸橼酸莫沙必利胶囊,5 mg,每日3次.两组均联用复方聚乙二醇电解质散(PEG)13.125 g,每日2次,疗程4周.观察两组患者首次排便和排便困难缓解时间、每周完全自发排便(SCBM)平均次数、排便困难、大便性状、不良反应及生命质量的变化.结果两组慢传输型、排便障碍型的治疗有效率比较,差异均有统计学意义(P<0.05),混合型差异无统计学意义(P>0.05).与莫沙必利组比较,普卢卡必利组首次排便时间和排便困难缓解时间均较短,差异有统计学意义(P<0.05).治疗后4周,两组患者SCBM>3次,普卢卡必利组次数更多;普芦卡必利组排便困难改善更为明显,差异有统计学意义(P<0.05).大便性状改善组间比较,差异无统计学意义(P>0.05).两组总有效率比较差异有统计学意义(P<0.05),不良反应发生率比较差异无统计学意义(P>0.05).治疗后4周,两组患者便秘患者生存质量自评量表(PAC-QOL)评分的总均分均有下降,普芦卡必利组降低更为明显,差异有统计学意义(P<0.05).结论普芦卡必利+PEG治疗老年难治性功能性便秘起效更快,且在总体疗效及生命质量改善方面有优势,尤适用于慢传输型和排便障碍型.%Objective To compare the short-term curative effects of prucalopride and mosapride respectively combined with low dose polyethylene glycol in treating elderly refractory functional constipation.Methods Ninety patients with elderly refractory functionalconstipation in the outpatient department of our hospital from May 2014 to February 2016 were retrospectively analyzed and divided into two groups randomly,45 cases in each group.the prucalopridegroup:Prucalopride Succinate Tablets,2mg,4 times daily;the mosapride group:Mosapride Citrate Capsules,5mg,3 times daily.Polyethylene Glycol Electrolytes Powder(PEG) was also used in the two groups,13.125g,twice daily.The course of treatment was 4 weeks.The first defecating time and defecation difficulty relief time,average weekly spontaneous complete bowel movements (SCBM),defecating difficulty,stool character,adverse reactions and change of life quality were observed in the twogroups.Results The treatment effective rate of slow transit constipation(STC) and defecatory disorder had the statistical difference between the two groups (P<0.05).The comparison of the effective rates in mixed type showed no statistical difference between the twogroups(P>0.05).Compared with the mosapride group,the first defecating time and defecation difficulty relief time in the prucalopride group were shorter with statistical difference (P<0.05).After 4-week treatment,SCBM times per week in the two groups were more than 3 times;the times of the prucalopride group were even more.In the prucalopride group,the defecation difficulty improvement was more obvious,the difference between the two groups had statistical significance (P<0.05).As for the comparison of the stool character improvement,the difference had no statistical significance(P>0.05).The total effective rate had statistical difference between the two groups(P<0.05).The incidence rate of adversereactions had no statistical difference between the two groups(17.78%vs.15.56%,P<0.05).The total average score of PAC-QOL after treatment in the two groups were both decreased,moreover the decrease in the prucalopride group was more obvious;the difference between the two groups had statistical significance(P<0.05).Conclusion Prucalopride +PEG take effect faster in the treatment of elderly refractory functional constipation and has the advantages in the aspects of overall curative effect and life quality improvement,which is specially suitable for STC and defecatory disorder type.【期刊名称】《重庆医学》【年(卷),期】2017(046)020【总页数】4页(P2793-2796)【关键词】难治性功能性便秘;老年;聚乙二醇;琥珀酸普芦卡必利;枸橼酸莫沙必利【作者】黄海辉;张小敏;赵亮【作者单位】广东省河源市源城区人民医院消化内科 517000;广东省河源市源城区人民医院消化内科 517000;广东省河源市源城区人民医院消化内科 517000【正文语种】中文【中图分类】R57我国60岁以上人群慢性便秘的患病率高达22%，其中约50%为功能性便秘[1-3]。

胃结肠反射的研究概况

胃结肠反射的研究概况黄敏;陈继红;谭诗云;罗和生;JanDHUIZINGA【摘要】Gastrocolic reflex is one of physiological phenomenon in gastrointestinal tract,which is involved in the development of functional gastrointestinal disorders and has potential clinical value. Main methods for research on gastrocolic reflex are electromyography and colon manometry,increases of colonic spike bursts and colonic motility index occur after meal. Recent studies showed specific postprandial colonic motor patterns by using manometry,however,the mechanism of gastrocolic reflex is still uncertain. This article reviewed the study on gastrocolic reflex.%胃结肠反射是胃肠道生理现象之一，参与功能性胃肠疾病的发生和发展，具有潜在的临床价值。

胃结肠反射的研究方法主要为肌电图和结肠测压法，可见餐后结肠尖峰突发波或结肠动力指数增加。

近年应用测压法发现餐后结肠具有特定的运动模式，但胃结肠反射的表现方式和机制仍不清楚。

本文就胃结肠反射的研究概况作一综述。

【期刊名称】《胃肠病学》【年(卷),期】2016(021)008【总页数】4页(P505-508)【关键词】胃结肠反射;进食;肌电描记术;测压法【作者】黄敏;陈继红;谭诗云;罗和生;JanDHUIZINGA【作者单位】武汉大学人民医院消化内科消化系统疾病湖北省重点实验室430060;武汉大学人民医院消化内科消化系统疾病湖北省重点实验室 430060;武汉大学人民医院消化内科消化系统疾病湖北省重点实验室 430060;武汉大学人民医院消化内科消化系统疾病湖北省重点实验室 430060;麦克马斯特大学健康科学学院医学【正文语种】中文结肠功能紊乱性疾病如便秘为最常见的疾病之一，但其发病机制仍未完全阐明。

声音是一种由物体振动引发的物理现象(课堂PPT)

6
• 次声 • 人耳能听见的声音 • 超声 • 特超声
0～20Hz 20Hz～20KHz 20KHz～1GHz 1GHz～10THz
• Infra-sound
from 0 to 20 Hz
• Human hearing frequency range from 20Hz to 20kHz
• Ultrasound
1
•Байду номын сангаас声音和音频技术涉及的主要是声波(声学信号)的处理。
编码、录音机或数字音频带的存储、音乐及语音处理是这一领域的主要课题。
• Sound methodology and audio techniques engage in processing these sound waves (acoustic signals). Important topics in this area are coding, storage on recorders or digital audio tapes, music and speed processing.
• The waveform repeats the same shape at regular intervals and this portion is called a period. Since sound waves occur naturally, they are never perfectly smooth or uniformly periodic. However, sounds that display a recognizable periodicity tend to be more musical than those that are nonperiodic. Examples of periodic sound sources are musical instruments, vowel sounds, the whistling wind and bird songs. Nonperiodic sound sources include unpitched percussion instruments, coughs and sneezes and rushing water.

皇冠 XLS系列功放

Obteniendo otras Versiones de Idioma: Para obtener información en otro idioma acerca del uso de este producto, contacte por favor a su Distribuidor Crown local. Si necesita asistencia para localizar a su distribuidor local, favor de contactar a Crown al 574-294-8000. Este manual no incluye todos los detalles de diseño, producción, o variaciones del equipo. Tampoco cubre cualquier posible situación que pueda surgir durante la instalación, operación o mantenimiento. La información provista en este manual fue considerada precisa a la fecha de publicación. Sin embargo, pueden haber ocurrido actualizaciones a esta información. Para obtener la última versión de este manual, por favor visite la página de internet de Crown en . Nota de Marcas Registradas: Crown, Crown Audio y Amcron son marcas registradas de Crown International. Otras marcas son de la propiedad de sus respectivos dueños. Algunos modelos pueden ser exportados bajo el nombre de . Amcron ® Derechos reservados por Crown Audio Inc, ©2008., 1718 W. Mishawaka Rd., Elkhart Indiana 46517-9439 U.S.A® 001-574-294-8000 .,

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

ORIGINAL ARTICLEIs high amplitude propagated contraction present after transanal endorectal pull-through for Hirschsprung’s disease?Miyuki Kohno ÆHiromichi Ikawa ÆKunio Konuma ÆHiroaki Masuyama ÆHironori Fukumoto ÆEri MorimuraPublished online:27July 2007ÓSpringer-Verlag 2007Abstract The transanal endorectal pull-through (TAEPT)procedure is now widely performed for Hirschsprung’s disease (HD),however,the colorectal function after TAEPT has not yet been adequately assessed.We evaluated the postoperative clinical outcome and colorectal function based on lower colonic manometry after TAEPT.Twenty-one cases of HD underwent TAEPT from 1998to 2005.We examined the clinical outcome based on the requirement of enemas/suppositories,the number of defecations per day,the severity of perianal erosion,and the incidence of enterocolitis requiring hospital ing a three-channel Dentsleeve catheter and UPS-2020measuring device,we performed postoperative colonic manometry at three loca-tions:(1)the anal canal,(2)5cm proximal to the anal canal,and (3)10cm proximal to the anal canal,during defecation,and then we measured the appearance of high-amplitude contraction (HAC)(duration ‡10s,amplitude ‡100cmH 2O).Four of 21cases were treated with enemas/sup-positories no longer than 1year.The number of defecations decreased gradually from 4to 5per day in the early post-operative period,reaching 2to 3per day about 1year postoperatively.Perianal erosion was noted in 3of 21cases but it disappeared within three postoperative years.Two cases had enterocolitis.Lower colon manometry was per-formed in eight cases.Manometry during defecation was successfully monitored in six cases.HAC occurred in ﬁve of six cases (83.3%).The clinical outcomes after TAEPT were satisfactory in almost all cases.These good outcomes werepossibly due to the occurrence of HAC during defecation,though HAC did not ﬁll the deﬁnition of high amplitude propagated contractions (HAPCs).The occurrence of HAC after TAEPT might be caused by keeping any damage to the mesenteric ascending cholinergic nerve to a minimum during surgery.Further long-term observations are still re-quired to make an adequate assessment of such cases.Keywords Hirschsprung’s disease ÁTransanal endorctal pull-through ÁColonic manometryIntroductionThe one-stage transanal endorectal pull-through (TAEPT)procedure,which does not require either a laparotomy or laparoscopic assistance,has been recently advocated for the treatment of Hirschsprung’s disease (HD)[1].These methods are used because the procedures are less invasive,resulted in better esthetics and cause less postoperative pain and complications than a laparotomy.Short segment aganglionosis occurring distal to the sigmoid colon is a good indication for transanal endorectal pull-through without laparoscopic assistance or a laparotomy [2].The colorectal function after TAEPT,however,has not yet been adequately assessed for colorectal monometry during def-ecation,yet.The clinical outcomes and lower colon manometry during defecation after TAEPT of short seg-ment aganglionosis were investigated.Materials and methodsAt our institution,transanal Soave pull-through based on the prolapsing technique has been performed for theM.Kohno (&)ÁH.Ikawa ÁK.Konuma ÁH.Masuyama ÁH.Fukumoto ÁE.Morimura Department of Pediatric Surgery,Kanazawa Medical University,1-1Daigaku,Uchinada-machi,Kahoku-gun,Ishikawa 920-0293,Japan e-mail:miyuki@kanazawa-med.ac.jpPediatr Surg Int (2007)23:981–986DOI 10.1007/s00383-007-1981-ztreatment of HD,since1998.The subjects consisted of21 cases(18boys and3girls)who underwent the TAEPT procedure for short-segment rectal or rectosigmoid agan-glionosis from1998to2005.HD was conﬁrmed by a suction biopsy of the rectal mucosa in all patients.We investigated clinical outcome based on the require-ment of enemas/suppositories,the number of defecations per day,the severity of perianal erosion,and the incidence of enterocolitis requiring hospital stay.Follow-up infor-mation was obtained from outpatients visit notes and telephone interviews.Using a three-channel Dentsleeve catheter and UPS-2020measuring device,we performed postoperative co-lonic manometry at three locations:(1)the anal canal,(2) 5cm proximal to the anal canal,and(3)10cm proximal tothe anal canal,during defecation.All the measurements were performed without sedation.No drugs for inducing defecation were used during our measurements.The pat-terns of colon contractions during defecation were identi-ﬁed by a qualitative analysis.High-amplitude contraction (HAC)was deﬁned as contraction with amplitude of at least100cmH2O,lasting more than10s.ResultsThe median age at the time of surgery was2months (range,22days–9years),and seven patients were neo-nates.The median body weight at surgery was 5.1kg (range, 3.3–32.5kg).The median follow-up time after TAEPT in21cases was58months(range,13–84months). Enemas/suppositories were administered in four cases (19.0%)out of the21cases.Three of the four cases re-quired enemas/suppositories within1year.In the remain-ing one case,who had a Smad interacting protein1defect disease,enemas has been used one time per day for con-stipation up to the present,for3years after undergoing TAEPT.The number of defecations decreased gradually from4to5per day in the early postoperative period,while reaching2to3per day at about1year postoperatively (Fig.1).The frequency of defecation per day gradually declined with an elapse of a postoperative year.After one postoperative year,the frequency of defecation per day did not change greatly.Perianal erosion was noted in three out of21cases,but it disappeared within three postoperative years.Enterocolitis requiring hospital stay occurred in two cases.In addition,one case developed enterocolitis due to a rotavirus infection.Results of colonic manometry on defecationLower colon manometry was performed in eight cases (Table1).The median age at the time of manometry was 34months(range,26–52months).The median interval between TAEPT and manometric studies was31months (range,14–50months).The median anal resting pressure was29cmH2O(range,15–52.3cmH2O).Manometry during defecation was successfully monitored in six of eight cases.HAC during defecation occurred inﬁve of six cases(83.3%)(Figs.2,3,4).In the remaining one case, moderate amplitude contraction occurred during defeca-tion.Even though a decrease in the anal pressure to below baseline was observed during the defecation in a few cases, none of them exhibited a normal anorectal reﬂex following rectal balloon inﬂation.DiscussionLaparoscopic radical surgery for HD[3–6]has been established as a form of minimally invasive surgery.Fur-thermore,for short segment aganglionosis,radical surgery by the transanal route alone without requiring any laparo-scopic assistance(TAEPT)[1]has been reported,and it has now become widely used because of its safety and less invasive nature.As for the defecation function after radical surgery with a conventional laparotomy,it has often been reported that the incidence of constipation or fecal incon-tinence is not always satisfactory[7–9].Conversely,it has often been reported that the defecation function after TA-EPT is good[10–13],and it was also generally observed not to be problematic in our study results.Regarding tests to verify the clinical evaluation,there have been some re-ports of studies with anorectal pressure such as the resting anal pressure and the anorectal reﬂex[12,14,15],but there have been very few reports regarding colonic motility during defecation.Therefore,in addition to the normal clinical evaluation after TAEPT,the manometryﬁndings of colonic motility during defecation were investigated.With TAEPT,it was feared that the enlargement and extension of the anal sphincter for transanal surgery could)91=n()81=n()12=n(11=n()31=n()51=n(damage defecation function,but recent reports have indi-cated that the resting anal sphincter pressure 1–2years after surgery does not differ from that of the laparotomy group [14],and that no physiological damage occurs [15].While the frequency of defecation increases in the early postop-erative period because of the effects of enlargement and extension of the anal sphincter,it is believed that the effects of enlargement and extension will gradually disappear [13].El-Sawaf et al.[16]reported that continence was unsatis-factory in the long-term outcomes of TAEPT compared to laparotomy,thus indicating that overstretching of the anal sphincter and mucosal sensory nerves damaged by anasto-mosis just above the dentate line could be the cause.We also experienced cases in which staining could sometimes be observed even when the frequency of defecation is 1–2per day,so further investigation,including an internal sphincter myotomy,is believed to be required.As one of the indications that the defecation function after TAEPT is good,we assume that the normal lower colon movement maintained during defecation may be involved,because HAC occurred in ﬁve of the six cases (83.3%)in which pressure during defecation could be measured.Successful defecation requires three actions:(1)stool moving into the rectum,(2)pelvic ﬂoor relaxation,and (3)an increase in intraabdominal pressure [17].High-amplitude propagated contractions (HAPCs)are the man-ometric equivalent of mass movements [18,19].HAPCs play an important role in defecation.HAPCs were deﬁned as contraction with an amplitude of at least 60mmHg (=81.7cmH 2O),lasting more than 10s and propagating aborally across 30cm or more [17–19].Because our method of measurement is to measure a 15-cm-long range,it could not be determined whether it was propagated orally across a range of 30cm or more.However,since all theTable 1Lower colonic manometry on spontaneous defecation and the clinical outcome in eight cases No Age atmanometric study Age at TAEPT Anal resting pressure(cmH 20)Amplitude of contractions (cmH 20)Duration ofcontractions (s)Enemas/suppositories No.of defecations (per day)Perianal erosion Enterocolitis 1.4years 4months 4months 15.06726.0No 2.5No No 2.4years 3months 1months19.316111.0No 0.5No Yes 3.3years 7months 2years 5months 39.011610.0No 2.5No No 4.2years 11months 1months18.015117.0No 1.5No No 5.2years 9months 28days 46.3––No 4.0No No 6.2years 8months 2months 34.017613.2Yes 4.5Yes No 7.2years 6months 2months 24.015310.0No 3.5Yes No 8.2years 2months2months52.3––No1.0NoNoFig.2Lower colonicmanometry during defecation in case 2(4-years-3-month-old boy).High-amplitude contraction (HAC)is seenduring defecation,however,the anal pressure does not show relaxationﬁve cases of HAC were observed related to defecation [17],we believe that it is highly possible that it is the same as that for HAPCs.The presence of HAPCs is suggestive of a normal colonic function.HAPCs may be a manometric marker for colonic neuromuscular integrity [17].However,the coordination of anal function with HAPCs is still not completely understood.There have been very few reports in which the defecation function has been investigated after surgery for HD from colonic pressure motility,and all reports are related to investigation with laparotomy.Zaslavsky and Loening-Baucke [20]observed spontane-ous high amplitude contractions (‡50mmHg =68.1cmH 2O)at rest recorded in the rectum for 10of 28pa-tients (36%)but mentioned that the presence of propul-sive waves was not a prognostic indicator for achieving bowel control,because not all the clinical evaluations were good.Similarly,in rectal manometry,Keshtgar et al.[21]also mentioned that hyperperistaltic waves in the neorectum may have overcome anal sphincter resistance leading to fecal incontinence.Di Lorenzo et al.[22],and Martin et al.[23]mentioned that total colonic manometry can provide valuable information regarding the location and type of dysmotility and it can also be used to plan surgical intervention or assess the response to medical therapy.In particular,Di Lorenzo et al.[22]categorized four motility patterns from the colonic motility measure-ments of unsatisfactory,poor-outcome patients aftersur-Fig.3Lower colonicmanometry during defecation in case 3(3-year-7-month-old boy).HACs are seen during defecation andﬂatulationFig.4Lower colonicmanometry during defecation in case 7(2-year -6-month-old boy).HAC is seen during defecation,however,the anal pressure does not show relaxationgery for HD with conditions such as fecal incontinence or soiling,constipation,and abdominal pain,and mentioned that the group with abnormal colonic manometry, including the absence of HAPCs or persistent simulta-neous contractions over two or more recording sites,most likely had a neuropathic motility disorder proximal to the aganglionic colon.In addition,while there was a group with symptoms in the presence of normal HAPCs,in our cases of colonic motility in which HAPCs was observed during defecation,with the exception of one case of constipation,no symptoms such as soiling,abdominal pain,and vomiting were observed.The parasympathetic(cholinergic)nerves from the pelvic plexus ascend along the colonic wall as far as the splenicﬂexure and distal parts of the transverse colon. These nerves play an important role in the motility of the colon and defection.The occurrence of HAC after TA-EPT might be caused by keeping any damage to the mesenteric ascending cholinergic nerve to a minimum during surgery.The clinical outcomes after TAEPT were satisfactory in almost all cases.These good outcomes were possibly due to the occurrence of HAC during defecation.It is said that HAPCs are normally associated with the relaxation of the anal sphincter[24]and hyper-tensive anal sphincter is believed to be one of the causes of postoperative constipation[22].There has been some discussion as to the absence or presence of the anorectal reﬂex[20],but none of our patients exhibited a normal anorectal reﬂex following rectal balloon inﬂation.More-over,no anal sphincter relaxation was observed following HAC,in the cases in which HAC occurred.In the internal anal sphincter of HD,the inhibitory neural control by non-adrenergic,non-cholinergic inhibitory motor neurons is absent[25]and the innervation of the internal anal sphincter thus would not change after radical surgery for HD.Therefore,the normal anorectal reﬂex could not be present even after TAEPT.Further long-term observation is needed in order to make an adequate assessment.We believe that the accu-mulation of further results regarding colonic motility are thus needed to support the clinical evaluation of defecation after TAEPT.References1.De la Torre-Mondragon L,Ortega-Salgado JA(1998)Transanalendorectal pull-through for Hirschsprung’s disease.J Pediatr Surg 33:1283–12862.Albanese CT,Jennings RW,Smith B,Bratton B,Harrison MR(1999)Perineal one-stage pull-through for Hirschsprung’s dis-ease.J Pediatr Surg34:377–3803.Smith BM,Stein RB,Lobe TE(1994)Laparoscopic Duhamelpullthrough procedure for Hirschsprung’s disease in childhood.J Laparoendosc Surg4:273–2764.Georgeson KE,Fuenfer MM,Hardin WD(1995)Primary lapa-roscopic pull-through for Hirschsprung’s disease in infants and children.J Pediatr Surg30:1017–10225.Curran TJ,Raffensperger JG(1996)Laparoscopic Swenson pull-through:a comparison with the open procedure.J Pediatr Surg 31:1155–11576.Morikawa Y,Hoshino K(1997)A new laparoscopic techniquefor Hirschsprung’s disease:the prolapsing technique.Pediatr Endosurg Innovat Tech1:131–1347.Catto-Smith AG,Coffey CM,Nolan TM,Hutson JM(1995)Fecal incontinence after the surgical treatment of Hirschsprung disease.J Pediatr127:954–9578.Moor SW,Albertyn R,Cywes S(1996)Clinical outcome andlong-term quality of life after surgical correction of Hirsch-sprung’s disease.J Pediatr Surg31:1496–15029.Yanchar NL,Soucy P(1999)Long-term outcome after Hirsch-sprung’s disease:patients’perspectives.J Pediatr Surg34:1152–1160nger JC,Durrant AC,de la Torre L,Teitelbaum DH,MinkesRK,Caty MG,Wildhaber BE,Ortega SJ,Hirose S,Albanese CT (2003)One-stage transanal Soave pullthrough for Hirschsprung disease:a multicenter experience with141children.Ann Surg 238:569–57611.Hadidi A(2003)Transanal endorectal pull-through for Hirsch-sprung’s disease:experience with68patients.J Pediatr Surg 38:1337–134012.Peterlini FL,Martins JL(2003)Modiﬁed transanal rectosigmoi-dectomy for Hirschsprung’s disease:clinical and manometric results in the initial20cases.J Pediatr Surg38:1048–1050 13.Elhalaby EA,Hashish A,Elbarbary MM,Soliman HA,WishahyMK,Elkholy A,Abdelhay S,Elbehery M,Halawa N,Gobran T, Shehata S,Elkhouly N,Hamza AF(2004)Transanal one-stage endorectal pull-through for Hirschsprung’s disease:a multicenter study.J Pediatr Surg39:345–35114.van Leeuwen K,Geiger JD,Barnett JL,Coran AG,TeitelbaumDH(2002)Stooling and manometricﬁndings after primary pull-through in Hirschsprung’s disease:perineal versus abdominal approaches.J Pediatr Surg37:1321–132515.Till H,Heinrich M,Schuster T,Schweinitz DV(2006)Is theanorectal sphincter damaged during a transanal endorectal pull-through(TERPT)for Hirschsprung’s disease?A3-dimensional, vector manometric investigation.Eur J Pediatr Surg16:188–19116.El-Sawaf MI,Drongowski RA,Chamberlain JN,Coran AG,Teitelbaum DH(2007)Are the long-term results of the transanal pull-through equal to those of the transabdominal pull-through?A comparison of the2approaches for Hirschsprung disease.J Pe-diatr Surg42:41–4717.Hamid SA,Di Lorenzo C,Reddy SN,Flores AF,Hyman PE(1998)Bisacodyl and high-amplitude-propagating colonic con-tractions in children.J Pediatr Gastroenterol Nutr27:398–402 18.Narducci F,Bassotti G,Gaburri M,Morelli A(1987)Twenty fourhour manometric recording of colonic motor activity in healthy man.Gut28:17–2519.Bassotti G,Gaburri M(1988)Manometric investigation of high-amplitude propagated contractile activity of the human colon.Am J Physiol255:G660–G66420.Zaslavsky C,Loening-Baucke V(2003)Anorectal manometricevaluation of children and adolescents postsurgery for Hirsch-sprung’s disease.J Pediatr Surg38:191–19521.Keshtgar AS,Ward HC,Clayden GS,de Sousa NM(2003)Investigations for incontinence and constipation after surgery for Hirschsprung’s disease in children.Pediatr Surg Int19:4–8 22.Di Lorenzo C,Solzi GF,Flores AF,Schwankovsky L,Hyman PE(2000)Colonic motility after surgery for Hirschsprung’s disease.Am J Gastroenterol95:1759–176423.Martin MJ,Steele SR,Mullenix PS,Noel JM,Weichmann D,Azarow KS(2004)A pilot study using total colonic manometry in the surgical evaluation of pediatric functional colonic obstruction.J Pediatr Surg39:352–35924.Malcolm A,Camilleri M(2000)Coloanal motor coordination inassociation with high-amplitude colonic contractions after phar-macological stimulation.Am J Gastroenterol95:715–71925.Matsufuji H(1990)Responses of muscle strips from the internalanal sphincter in Hirschsprung’s disease to drugs and electrical ﬁeld stimulation.Nippon Heikatsukin Gakkai Zasshi26:199–218。