Multiquark states in a Goldstone boson exchange model
量子力学第二版(周世勋)
2µ
2µ
= qBnη = nB ⋅ qη
2µ
2µ
= nBNB ,
其中， M B
=
qη 2µ
是玻尔磁子，这样，发现量子化的能量也是等间隔的，而且
具体到本题，有
∆E = BM B
根据动能与温度的关系式
∆E = 10 × 9 × 10−24 J = 9 × 10−23 J
E = 3 kT 2
以及
1k ⋅ K = 10−3 eV = 1.6 × 10−22 J
∂ ∂r
(1 eikr ) − r
1 eikr r
∂ ∂r
(1 r
e
−ikr
ρ )]r0
=
iη [1 (− 2m r
1 r2
+ ik 1) − 1 (− rr
1 r2
−
ik
1 r
)]ρr0
可见，
ρ J2
=
−
ηk mr 2
ρr0
=
−
ηk mr 3
ρr
与rρ反向。表示向内(即向原点) 传播的球面波。
补充：设ψ (x) = eikx ，粒子的位置几率分布如何？这个波函数能否归一化？
1．3 氦原子的动能是 E = 3 kT （k 为玻耳兹曼常数），求 T=1K 时，氦原子的德布罗意波 2
长。
解 根据
2
PDF 文件使用 "pdfFactory Pro" 试用版本创建
知本题的氦原子的动能为
1k ⋅ K = 10−3 eV ，
E = 3 kT = 3 k ⋅ K = 1.5 ×10−3 eV , 22
解 关于两个光子转化为正负电子对的动力学过程，如两个光子以怎样的概率转化为正 负电子对的问题，严格来说，需要用到相对性量子场论的知识去计算，修正当涉及到这个过 程的运动学方面，如能量守恒，动量守恒等，我们不需要用那么高深的知识去计算，具休到 本题，两个光子能量相等，因此当对心碰撞时，转化为正风电子对反需的能量最小，因而所 对应的波长也就最长，而且，有
abaqus问答集合
1．ABAQUS的UMAT一点看法：如果本构模型复杂，应力应变关系是非线性的隐式表达，就需要进行迭代，更新应力。
这就是UMAT 的最重要的任务。
那么这样一来，在给定应变增量的情况下更新应力，就必须求解应变对应力的导数，运用迭代，如N-R迭代。
这样一来，在UMAT中就需要求解两次导数。
（DDSDDE为一次）所以比较麻烦的。
对于时间相关的本构模型来说更是麻烦。
2．使用abaqus求解螺栓和螺母接触螺纹的强度所碰到的问题1．Solver problem. Zero pivot when processing D.O.F. 1 of 49 nodes. The nodes have been identified in node set warnnodesolvprobzeropiv_1_1_1_1_1.（是什么原因造成的？）2。
The system matrix has 6276 negative eigenvalues..（是什么原因造成的？）3。
1304 nodes may have incorrect normal definitions. The nodes have been identified in node set warnnodeincorrectnormal.（这个法向量错误在模型中显示为螺母内部的接触面，但我反了一下法向量还是同样错误）4。
Program is asked to invert a singular matrix.（是什么原因造成的？）2．模型就是一个螺母和螺栓之间夹一个平板的简单模型边界条件施加如下：固定螺栓的下端，在螺栓、平板、螺母之间分别建立surface to surface接触（带摩擦），然后在螺母上施加力矩，这样来求解螺栓预紧时螺纹接触部分的应力，但总是出现上述问题，请高手分析指点，谢谢！答：检查一下两个接触面之间是不是有初始的穿透；负特征值可能是因为你的初始步长太大了，接触的问题；保证模型中的每个零件在开始时有稳定的约束，可以考虑加一些软弹簧约束住；还可以用ajust使两个接触面在一开始就起上作用。
802_am_强子物理_乔从丰
强子物理
轻子家族
第一个轻子—电子
1931年，泡利为了解释β衰变中的能量失踪现象，预 言了一种未知的极其微小的中性粒子带走了β衰变中 那一部分能量和动量，最终被费米命名为“中微子” （Neutrino）。
1933年，费米指出：β衰变就是核内一个中子通过弱相互作 用衰变成一个电子、一个质子和一个 反中微子。中微子只 参与弱作用，具有最强的穿透力。由于中微子与物质间的相
夸克间相互作用
根据目前人类的认识，自然界有四种基本相互作用： 强相互作用、电磁相互作用、弱相互作用、万有引力
量子色动力学（QCD）是目前人类认识到的，自然 界中最基本的四种相互作用之一，是描述基本粒子 之间强相互作用的量子理论。
强相互作用
1964年，Greenberg引入了夸克的一种自由度——“颜 色”（color）夸克带颜色荷。每味夸克就有三种颜色 分别是红、绿和蓝（RGB）。
原子核 = 质子 + 中子
问题1：带正电的质子为何被束缚在一起？ 问题2：质子和中子是否具有内部结构？
强子物理
原子核内的相互作用—发现介子
1935年，日本科学家汤川秀树（Yukawa Hideki，1907-1981）提出了“交换粒子”的 概念，作为新相互作用理论的基本概念。
1936年，美国科学家安德森在宇宙线中发现一 种比电子约重207倍的粒子，当时误认为就是 介子，后来发现这种粒子其实并不参与强相互 作用是一种轻子，所以改名为μ子。
1909年卢瑟福指导他的学生做了一个著 名物理实验。他们用alpha粒子轰击金箔， 发现绝大多数alpha粒子与金原子的散射角 很小，但也有少数alpha粒子散射角很大， 甚至大于90度
他们由此推断，金原子内大部分空间 是空的，质量较大并带有正电荷的部分 集中在很小的，称之为核的区域
高斯型耦合多光子Tavis-Cummings模型中原子的量子特性
＝ｋ ｐ ， ＝ ｇ ｏ ＝
（） １
ｐ 腔 内沿 径 向的 长度变 量 ，。 为 ｌ 为腔 内光场 （） 少 为轴线 处 的 １ ｅ ｏ 厂 ￡减 ／
（） ２
摘
要 ：研究 了 多 光 子 跃迁 过 程 高 斯 型 耦 合 Ｔ ｖｓＣ ｍｍｉｇ 型 中 原 子 的 量 子 特 性 ． 用 了数 值 计 算 方 ａｉ ｕ — ｎ ｓ模 运
法 ， 论 了 多 光 子跃 迁过 程 中 ， 子 运 动 速 度 、 场 初 态 的平 均 光 子 数 、 迁 光 子 数对 双 原 子 能 级 布 居 数 反 转 和 双 讨 原 光 跃 原 子 偶 极 压 缩 的 影 响 ． 果 表 明 ， 子 运 动 速 度 的 变 化 改 变 了 双 原 子 能 级 布 居 数 反 转 和 双 原 子 偶 极 压 缩 与 光 场 的 结 原 有 效 作 用 时 间． 跃迁 光 子 数 的 变 化改 变 了双 原子 能 级 布居 数 反 转 和 双 原 子 偶 极 压 缩 时 间 演 化 曲 线 的振 荡 幅 度 和
收 稿 １ ；２ １ －２１ ３期 ０ ＩＩ－５ 基 金 项 目 ：内 蒙 古 自然 科 学 基 金 资助 项 目（ Ｏ ９ Ｏ １ ） ２ Ｏ ＭＳ ｌ ２ ；内蒙 古 师范 大 学 研 究 生 科 研 创新 基 金项 目 （ Ｘ Ｊ ｌ Ｏ ６ Ｃ ＪＳ ｏ ３ ） 作 者 简 介 ：张 学 光 （ ９ ７ ）男 ， １ ８ 一 ， 内蒙 古 通 辽 市 人 ， 蒙 古 师范 大 学 硕 士 研 究 生 内
Ｖ ｏ１ ＮＯ． ．４１ ３
Ｍａ ｙ ２０１ ２
高 斯 型 耦 合 多 光 子 Ｔａ ｉ Ｃｕ ｖｓ ｍｍｉｇ — ｎｓ 模 型 中原 子 的 量 子 特 性
Search for a new state of matter – the Quark-Gluon Plasma一个物质–夸克胶子等离子体的新状态搜索 43
-- multi-parton dynamics (recombination or coalescence or …)
-- Hydrodynamics (constituent quarks ? parton dynamics from gluons to constituent quarks? )
Nucleus-Nucleus Collisions and Volcanic Eruption
Volcanic high pT -- Strombolian eruption
Volcanic mediate pT – Spatter (clumps)
6
Volcanic low pT – Bulk matter flows
Evidence for Multi-parton Dynamics in Hadronization of Bulk Partonic Matter at RHIC
Huan Zhong Huang (黄焕中) Department of Physics and Astronomy
University of California Los Angeles
Rafelski+Danos, Molnar+Voloshin …..) Quark Recombination – (R.J. Fries et al, R. Hwa et al)
13
Constituent Quark Scaling
Constituent (n) Quark Scaling -- Meson n=2 and Baryon n=3 grouping
p td d td p N y d 2 1 π p td dtd p N 1 y i 12ic vo s ψ R () i)1( 0
量子力学英文名词
probability density probability wave normalizing condition Schrödinger equation stationary state stationary Schrödinger equation
势阱
对应原理
隧道效应
能量量子化
Paulaser 泡利不相容原理 激光 自发辐射 受激辐射 氦氖激光器 红宝石激光器
He-Ne laser
Pfund series Bohr quantization condition Bohr hydrogen atom Bohr frequency condition Bohr radius energy level
energy quantum photoelectric effect photo electron photocurrent cutoff potential difference red-limit wave-particle dualism
康普顿效应 康普顿散射 康普顿波长 反冲电子 莱曼系 帕邢系 布拉开系
主量子数
角动量量子化
potential well
correspondence principle
tunneling effect
energy quantization
principal quantum number
angular quantization
角量子数 空间量子化 磁量子数 电子自旋 自旋量子数 自旋磁量子数
Stefan-Boltzmann law Stefan constant Wien displacement law Rayleigh-Jens formula Planck radiation formula Planck constant
核子中奇异夸克分布不对称性与轻味夸克碎裂效应
29 10 2005 10HIGH ENERGY PHYSICS AND NUCLEAR PHYSICSVol.29,No.10Oct.,2005*( 100871)– , . , .D ..1, –[1—3]. ,. ,, –(DIS) (global analysis)[4,5], ,(intrinsic sea theory) ,µ CCFR NuTeV,[6,7]. ,. ,[4,8—12]NuTeVWeinberg [13,14],.. ,Fν2 F¯ν2,:Fν2−F¯ν2=2x[s(x)−¯s(x)]. ,,. c.CCFR NuTeV µ [6,15,16].νµs→µ−c νµd→µ−c,Cabibbo ,c ;, ¯c.CCFR NuTeV µµ+(µ−) c(¯c) ,c→H(c¯q)→µ+X. µ,µ ,. ,CCFR νµ(¯νµ) ,c(¯c) µ+(µ−) ¯B c(¯B¯c):¯Bc−¯B¯c0.1147∼0−20%[6]., ,µ . ,CCFR NuTeV µ,.( c ¯c10 965dξd y =G2s2|V cd|2].(1)s=2MEν ,r2≡(1+Q2/M2W)2.ξ . , c ,ξ Bjorken:ξ≈x(1+m2c /Q2). (1)f c≡1−m2c/2MEνξ c, [18]., ¯cd2σ¯νµN→µ+¯c Xπr2f c•ξ[¯s(ξ)|V cs|2+¯d(ξ)+¯u(ξ)dξd y−d2σ¯νµN→µ+¯c Xπr2f c•ξ (s(ξ)−¯s(ξ))|V cs|2+d v(ξ)+u v(ξ)2ξ[d v(ξ)+u v(ξ)] ,|V cs|2≃0.95 |V cd|2≃0.05[19] .12S−|V cs|2+Q V|V cd|2,(4)S−≡ ξ[s(ξ)−¯s(ξ)]dξ,Q V≡ ξ[d v(ξ)+u v(ξ)]dξ., NuTeV.[9—12],NuTeV ., (4) ,c ¯c P SA( 1).1 NuTeV c ¯c P SADing-Ma[9]Q2030%—80%0.007—0.01812%—26% Alwall-Ingelman[10]20GeV230%0.00915% Ding-Xu-Ma[11]Q2060%—100%0.014—0.02221%—29% Wakamatsu[12]16GeV270%—110%0.022—0.03530%—40%966 (HEP&NP) 29 2S+|V cs|2+(Q V+2Q S)|V cd|2.(5)S+≡ ξ[s(ξ)+¯s(ξ)]dξ,Q S≡ ξ[¯u(ξ)+¯d(ξ)]dξ.CTEQ5 Q2=16GeV2 S+,Q V,Q S, |V cs|2=0.95,|V cd|2=0.05,1 2S−/Q V 0.007(0.022), R 20%(25%). ,c ¯c, c¯c.3 µ, , c,( µ) ( ) . cH+d3σνµN→µ−H+Xdξd y D H+q(z),(6)D H+q(z) q H+ ,z H+ q . H+ c D+(c¯d) D0(c¯u) ,H− D−(¯c d) ¯D0(¯c u).c H+ H+ . , Lund , q¯qexp(−bm2q)[20], s¯s λ∼0.3[21,22], c¯c 10−5., . µ [17]. . , e+e− . , , c ¯c , D , c , , , c(¯c) , µ . , c ¯c D(c¯q) ¯D(¯c q). , , , :u→cu),d→D−(dξd y d z=G2s2|V cd|2]+δ dσνN→µ−µ+Xdξd y d z LQF=G2s2|V ud|2(1−y)2,(8)D q(z)≡D Dq(z)+D D∗q(z), D Dq(z)≡D¯D0u(z)=D D0¯u(z)=D D−d(z)=D D+¯d(z),D D∗q(z)≡D¯D∗0u(z)=D D∗0¯u(z)=D D∗−d(z)=D D∗+¯d(z). , D q(z) q , . (8) ,¯BD(∗)+=1dξd y d z=G2s2|V cd|2]+δ dσ¯νN→µ+µ−Xdξd y d z LQF=G2s2•|V ud|2(1−y)2.(10)10 967(σνN→µ−µ+X−σ¯νN→µ+µ−X)total≈−1Q V|V cd|2+2S−|V cs|2•D q¯BD(∗)+¯f c ¯Bc.D q¯BD(∗)+d x d y d z=G2s2|V ud|2D q(z)B¯D0,(12),B¯D0 ¯D0 µ− , ¯D∗0¯D0 , B¯D0 .,µ+µ+d3σ¯νN→µ+µ+Xπr2x¯u(x)+¯d(x)σµ−µ+≈Q ud|V ud|2¯fc¯Bc,(14)Q ud≡1¯fc¯Bc,D qσµ−µ+.(15)CDHSW[26] ( )µ µ σµ−µ−/σµ−µ+(σµ+µ+/σµ+µ−). 2E vis 100—200GeV ,3 .2 , , σµ−µ−/σµ−µ+σµ−µ−/σµ− ,, σµ−µ−/σµ−µ+, ,.2CDHSW 100<E vis<200GeV µ [26]pµ>6GeV(3.5±1.6)%(1.6±0.74)×10−4(4.5±2.0)%(2.2±1.0)×10−4 pµ>9GeV(2.9±1.2)%(1.05±0.43)×10−4(4.4±1.8)%(1.7±0.7)×10−4 pµ>15GeV(2.3±1.0)%(0.52±0.22)×10−4(4.1±2.3)%(0.8±0.45)×10−4968 (HEP&NP) 29dξd y d z −d3σ¯νµN→µ+H−Xπr2f cξ[(s(ξ)−¯s(ξ))|V cs|2+ d v(ξ)+u v(ξ)πr2xd v(x)+u v(x)πr2xd v(x)+u v(x)10 969(References)1Brodsky S J,MA B-Q.Phys.Lett.,1996,B381:3172Signal A I,Thomas A W.Phys.Lett.,1987,B191:2053Burkardt M,Warr B J.Phys.Rev.,1992,D45:9584Olness F et al.hep-ph/03123235Barone V et al.Eur.Phys.J.,2000,C12:2436Bazarko A O et al(CCFR Collaboration).Z.Phys.,1995, C65:1897Mason D(NuTeV Collaboration).hep-ex/04050378Kretzer S et al.Phys.Rev.Lett.,2004,93:0418029DING Y,MA B-Q.Phys.Lett.,2004,B590:216;DING Yong,L¨U Zhun,MA Bo-Qiang.HEP&NP,2004,28(9): 947(in Chinese)( , , . ,2004,28(9):947) 10Alwall J,Ingelman G.Phys.Rev.,2004,D70:111505.11DING Y,XU R-G,MA B-Q.Phys.Lett.,2005,B607:101 12Wakamatsu M.hep-ph/041120313Zeller G P et al.Phys.Rev.Lett.,2002,88:09180214Zeller G P et al.Phys.Rev.,2002,D65:11110315Rabinowitz S A et al.Phys.Rev.Lett.,1993,70:13416Goncharov M et al.Phys.Rev.,2001,D64:11200617Godbole R M,Roy D P.Z.Phys.,1984,C22:39;Z.Phys., 1989,C42:21918Astier P et al(NOMAD Collaboration).Phys.Lett.,2000, B486:3519Eidelman S et al(Particle Data Group).Phys.Lett.,2004, B592:120Andersson B et al.Nucl.Phys.,1981,B178:24221Lafferty G D.Phys.Lett.,1995,B353:54122Abe K et al(SLD Collaboration).Phys.Rev.Lett.,1997, 78:334123Smith J,Valenzuela G.Phys.Rev.,1983,D28:107124Aitala E M et al(Fermilab E791Collaboration).Phys.Lett.,1996,B371:15725Dias de Deus J,Dur˜a es F.Eur.Phys.J.,2000,C13:647 26Burkhardt H et al.Z.Phys.,1986,C31:3927Sandler P H et al.Z.Phys.,1993,C57:1,and References Therein.28Jonker M et al.Phys.Lett.,1981,B107:24129de Lellis G et al.Phys.Rep.,2004,399:22730Kayis-Topaksu A et al(CHORUS Collaboration).Phys.Lett.,2002,B549:4831¨Oneng¨u t G et al(CHORUS Collaboration).Phys.Lett., 2004,B604:145Nucleon Strange Asymmetry and the Light QuarkFragmentation Effect*GAO Pu-Ze MA Bo-Qiang(School of Physics,Peking University,Beijing100871,China)Abstract Nucleon strange asymmetry is an important non-perturbative effect in the study of nucleon structure,but it has not been checked by experiments yet.For effectively measuring the nucleon strange asymmetry,we investigate the light quark fragmentation effect that may affect the measurement of the strange asymmetry.We suggest an inclusive measurement of charged and neutral charmed hadrons by using an emulsion target in the neutrino and antineutrino in-duced charged current deep inelastic scattering,in which the strange asymmetry effect and the light quark fragmentation effect can be separated.Key words strange asymmetry,light quark fragmentation,charged current deep inelastic scattering。
格劳博模型蒙特卡洛方法
NN B 2 N part b A TA s 1 [1 TB s b inel ] d s 0 NN A B TB s b 1 [1 TA s inel ] d 2s
0
HIT- HEP
Monte Carlo Glauber Model
述复合系统的多体散射问题。
• 七十年代，质子与核子散射实验中他的方法
得到验证，可以用来计算反应的总截面。
• 现在，ＧＬＡＵＢＥＲ模型用来计算重粒子
碰撞中的centrality
RHIC (Relativistic Heavy Ion Collider)
Glauber 模型——从理论上对多核子散射问题的参数进行估计
• 第一步：根据Woods-Saxon分布产生N个核子的位置矢量 • 第二步：确定原子核的指向（3个欧拉角，b）
d /db 2 b
• 第三步：计算Npart和Ncoll
比较核子间距与核子半径的大小如果
NN d NN 2 * rneucleon 2 * inel /
则发生碰撞
• 分析形式：计算2*(A+B+1)维积分
Impossible! 对金核有800多维度！
• Monte Carlo Glauber 方案
只考虑Npart和Ncoll
HIT- HEP
厚度函数 ：核子出现在流管中单位面积的概率
TA s A s , z A dz A
HIT- HEP
HIT- HEP
thanks
AB n
HIT- HEP
计算总非弹性散射截面，平均对撞数目，参与（损伤）核子数
梁伟红(广西师范大学)
16
f0(500) production is clearly dominant.
f0(980) shows up as a small peak.
17
Exp.
Conclusion: Our results agree with the experimental results. This gives a strong support to the idea of the low lying scalar mesons as being formed from the interaction of pairs of pseudoscalar mEexspo.ns.
(2)
1 12 f2
Tr[(
)2
M4 ],
( f 93 MeV) ——the pion decay constant
There are 5 coupled channels:
(1), 0 0(2), K K (3), K 0K 0(4), (5)
The V matrix elements are taken from
VP ApJ / cos , ( A 1, for an arbitrary normalizat ion)
invariant mass (Minv ) distributi on :
~t t BJ /
B J /
( pJ / cos ),
(in the B rest frame )
• Formalism
• Results and discussions • Summary
2n
• The nature of the light scalar mesons is a topic of longstanding debate.
C.parvum全基因组序列
DOI: 10.1126/science.1094786, 441 (2004);304Science et al.Mitchell S. Abrahamsen,Cryptosporidium parvum Complete Genome Sequence of the Apicomplexan, (this information is current as of October 7, 2009 ):The following resources related to this article are available online at/cgi/content/full/304/5669/441version of this article at:including high-resolution figures, can be found in the online Updated information and services,/cgi/content/full/1094786/DC1 can be found at:Supporting Online Material/cgi/content/full/304/5669/441#otherarticles , 9 of which can be accessed for free: cites 25 articles This article 239 article(s) on the ISI Web of Science. cited by This article has been /cgi/content/full/304/5669/441#otherarticles 53 articles hosted by HighWire Press; see: cited by This article has been/cgi/collection/genetics Genetics: subject collections This article appears in the following/about/permissions.dtl in whole or in part can be found at: this article permission to reproduce of this article or about obtaining reprints Information about obtaining registered trademark of AAAS.is a Science 2004 by the American Association for the Advancement of Science; all rights reserved. The title Copyright American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the Science o n O c t o b e r 7, 2009w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o m3.R.Jackendoff,Foundations of Language:Brain,Gram-mar,Evolution(Oxford Univ.Press,Oxford,2003).4.Although for Frege(1),reference was established rela-tive to objects in the world,here we follow Jackendoff’s suggestion(3)that this is done relative to objects and the state of affairs as mentally represented.5.S.Zola-Morgan,L.R.Squire,in The Development andNeural Bases of Higher Cognitive Functions(New York Academy of Sciences,New York,1990),pp.434–456.6.N.Chomsky,Reflections on Language(Pantheon,New York,1975).7.J.Katz,Semantic Theory(Harper&Row,New York,1972).8.D.Sperber,D.Wilson,Relevance(Harvard Univ.Press,Cambridge,MA,1986).9.K.I.Forster,in Sentence Processing,W.E.Cooper,C.T.Walker,Eds.(Erlbaum,Hillsdale,NJ,1989),pp.27–85.10.H.H.Clark,Using Language(Cambridge Univ.Press,Cambridge,1996).11.Often word meanings can only be fully determined byinvokingworld knowledg e.For instance,the meaningof “flat”in a“flat road”implies the absence of holes.However,in the expression“aflat tire,”it indicates the presence of a hole.The meaningof“finish”in the phrase “Billfinished the book”implies that Bill completed readingthe book.However,the phrase“the g oatfin-ished the book”can only be interpreted as the goat eatingor destroyingthe book.The examples illustrate that word meaningis often underdetermined and nec-essarily intertwined with general world knowledge.In such cases,it is hard to see how the integration of lexical meaning and general world knowledge could be strictly separated(3,31).12.W.Marslen-Wilson,C.M.Brown,L.K.Tyler,Lang.Cognit.Process.3,1(1988).13.ERPs for30subjects were averaged time-locked to theonset of the critical words,with40items per condition.Sentences were presented word by word on the centerof a computer screen,with a stimulus onset asynchronyof600ms.While subjects were readingthe sentences,their EEG was recorded and amplified with a high-cut-off frequency of70Hz,a time constant of8s,and asamplingfrequency of200Hz.14.Materials and methods are available as supportingmaterial on Science Online.15.M.Kutas,S.A.Hillyard,Science207,203(1980).16.C.Brown,P.Hagoort,J.Cognit.Neurosci.5,34(1993).17.C.M.Brown,P.Hagoort,in Architectures and Mech-anisms for Language Processing,M.W.Crocker,M.Pickering,C.Clifton Jr.,Eds.(Cambridge Univ.Press,Cambridge,1999),pp.213–237.18.F.Varela et al.,Nature Rev.Neurosci.2,229(2001).19.We obtained TFRs of the single-trial EEG data by con-volvingcomplex Morlet wavelets with the EEG data andcomputingthe squared norm for the result of theconvolution.We used wavelets with a7-cycle width,with frequencies ranging from1to70Hz,in1-Hz steps.Power values thus obtained were expressed as a per-centage change relative to the power in a baselineinterval,which was taken from150to0ms before theonset of the critical word.This was done in order tonormalize for individual differences in EEG power anddifferences in baseline power between different fre-quency bands.Two relevant time-frequency compo-nents were identified:(i)a theta component,rangingfrom4to7Hz and from300to800ms after wordonset,and(ii)a gamma component,ranging from35to45Hz and from400to600ms after word onset.20.C.Tallon-Baudry,O.Bertrand,Trends Cognit.Sci.3,151(1999).tner et al.,Nature397,434(1999).22.M.Bastiaansen,P.Hagoort,Cortex39(2003).23.O.Jensen,C.D.Tesche,Eur.J.Neurosci.15,1395(2002).24.Whole brain T2*-weighted echo planar imaging bloodoxygen level–dependent(EPI-BOLD)fMRI data wereacquired with a Siemens Sonata1.5-T magnetic reso-nance scanner with interleaved slice ordering,a volumerepetition time of2.48s,an echo time of40ms,a90°flip angle,31horizontal slices,a64ϫ64slice matrix,and isotropic voxel size of3.5ϫ3.5ϫ3.5mm.For thestructural magnetic resonance image,we used a high-resolution(isotropic voxels of1mm3)T1-weightedmagnetization-prepared rapid gradient-echo pulse se-quence.The fMRI data were preprocessed and analyzedby statistical parametric mappingwith SPM99software(http://www.fi/spm99).25.S.E.Petersen et al.,Nature331,585(1988).26.B.T.Gold,R.L.Buckner,Neuron35,803(2002).27.E.Halgren et al.,J.Psychophysiol.88,1(1994).28.E.Halgren et al.,Neuroimage17,1101(2002).29.M.K.Tanenhaus et al.,Science268,1632(1995).30.J.J.A.van Berkum et al.,J.Cognit.Neurosci.11,657(1999).31.P.A.M.Seuren,Discourse Semantics(Basil Blackwell,Oxford,1985).32.We thank P.Indefrey,P.Fries,P.A.M.Seuren,and M.van Turennout for helpful discussions.Supported bythe Netherlands Organization for Scientific Research,grant no.400-56-384(P.H.).Supporting Online Material/cgi/content/full/1095455/DC1Materials and MethodsFig.S1References and Notes8January2004;accepted9March2004Published online18March2004;10.1126/science.1095455Include this information when citingthis paper.Complete Genome Sequence ofthe Apicomplexan,Cryptosporidium parvumMitchell S.Abrahamsen,1,2*†Thomas J.Templeton,3†Shinichiro Enomoto,1Juan E.Abrahante,1Guan Zhu,4 Cheryl ncto,1Mingqi Deng,1Chang Liu,1‡Giovanni Widmer,5Saul Tzipori,5GregoryA.Buck,6Ping Xu,6 Alan T.Bankier,7Paul H.Dear,7Bernard A.Konfortov,7 Helen F.Spriggs,7Lakshminarayan Iyer,8Vivek Anantharaman,8L.Aravind,8Vivek Kapur2,9The apicomplexan Cryptosporidium parvum is an intestinal parasite that affects healthy humans and animals,and causes an unrelenting infection in immuno-compromised individuals such as AIDS patients.We report the complete ge-nome sequence of C.parvum,type II isolate.Genome analysis identifies ex-tremely streamlined metabolic pathways and a reliance on the host for nu-trients.In contrast to Plasmodium and Toxoplasma,the parasite lacks an api-coplast and its genome,and possesses a degenerate mitochondrion that has lost its genome.Several novel classes of cell-surface and secreted proteins with a potential role in host interactions and pathogenesis were also detected.Elu-cidation of the core metabolism,including enzymes with high similarities to bacterial and plant counterparts,opens new avenues for drug development.Cryptosporidium parvum is a globally impor-tant intracellular pathogen of humans and animals.The duration of infection and patho-genesis of cryptosporidiosis depends on host immune status,ranging from a severe but self-limiting diarrhea in immunocompetent individuals to a life-threatening,prolonged infection in immunocompromised patients.Asubstantial degree of morbidity and mortalityis associated with infections in AIDS pa-tients.Despite intensive efforts over the past20years,there is currently no effective ther-apy for treating or preventing C.parvuminfection in humans.Cryptosporidium belongs to the phylumApicomplexa,whose members share a com-mon apical secretory apparatus mediating lo-comotion and tissue or cellular invasion.Many apicomplexans are of medical or vet-erinary importance,including Plasmodium,Babesia,Toxoplasma,Neosprora,Sarcocys-tis,Cyclospora,and Eimeria.The life cycle ofC.parvum is similar to that of other cyst-forming apicomplexans(e.g.,Eimeria and Tox-oplasma),resulting in the formation of oocysts1Department of Veterinary and Biomedical Science,College of Veterinary Medicine,2Biomedical Genom-ics Center,University of Minnesota,St.Paul,MN55108,USA.3Department of Microbiology and Immu-nology,Weill Medical College and Program in Immu-nology,Weill Graduate School of Medical Sciences ofCornell University,New York,NY10021,USA.4De-partment of Veterinary Pathobiology,College of Vet-erinary Medicine,Texas A&M University,College Sta-tion,TX77843,USA.5Division of Infectious Diseases,Tufts University School of Veterinary Medicine,NorthGrafton,MA01536,USA.6Center for the Study ofBiological Complexity and Department of Microbiol-ogy and Immunology,Virginia Commonwealth Uni-versity,Richmond,VA23198,USA.7MRC Laboratoryof Molecular Biology,Hills Road,Cambridge CB22QH,UK.8National Center for Biotechnology Infor-mation,National Library of Medicine,National Insti-tutes of Health,Bethesda,MD20894,USA.9Depart-ment of Microbiology,University of Minnesota,Min-neapolis,MN55455,USA.*To whom correspondence should be addressed.E-mail:abe@†These authors contributed equally to this work.‡Present address:Bioinformatics Division,Genetic Re-search,GlaxoSmithKline Pharmaceuticals,5MooreDrive,Research Triangle Park,NC27009,USA.R E P O R T S SCIENCE VOL30416APRIL2004441o n O c t o b e r 7 , 2 0 0 9 w w w . s c i e n c e m a g . o r g D o w n l o a d e d f r o mthat are shed in the feces of infected hosts.C.parvum oocysts are highly resistant to environ-mental stresses,including chlorine treatment of community water supplies;hence,the parasite is an important water-and food-borne pathogen (1).The obligate intracellular nature of the par-asite ’s life cycle and the inability to culture the parasite continuously in vitro greatly impair researchers ’ability to obtain purified samples of the different developmental stages.The par-asite cannot be genetically manipulated,and transformation methodologies are currently un-available.To begin to address these limitations,we have obtained the complete C.parvum ge-nome sequence and its predicted protein com-plement.(This whole-genome shotgun project has been deposited at DDBJ/EMBL/GenBank under the project accession AAEE00000000.The version described in this paper is the first version,AAEE01000000.)The random shotgun approach was used to obtain the complete DNA sequence (2)of the Iowa “type II ”isolate of C.parvum .This isolate readily transmits disease among numerous mammals,including humans.The resulting ge-nome sequence has roughly 13ϫgenome cov-erage containing five gaps and 9.1Mb of totalDNA sequence within eight chromosomes.The C.parvum genome is thus quite compact rela-tive to the 23-Mb,14-chromosome genome of Plasmodium falciparum (3);this size difference is predominantly the result of shorter intergenic regions,fewer introns,and a smaller number of genes (Table 1).Comparison of the assembled sequence of chromosome VI to that of the recently published sequence of chromosome VI (4)revealed that our assembly contains an ad-ditional 160kb of sequence and a single gap versus two,with the common sequences dis-playing a 99.993%sequence identity (2).The relative paucity of introns greatly simplified gene predictions and facilitated an-notation (2)of predicted open reading frames (ORFs).These analyses provided an estimate of 3807protein-encoding genes for the C.parvum genome,far fewer than the estimated 5300genes predicted for the Plasmodium genome (3).This difference is primarily due to the absence of an apicoplast and mitochondrial genome,as well as the pres-ence of fewer genes encoding metabolic functions and variant surface proteins,such as the P.falciparum var and rifin molecules (Table 2).An analysis of the encoded pro-tein sequences with the program SEG (5)shows that these protein-encoding genes are not enriched in low-complexity se-quences (34%)to the extent observed in the proteins from Plasmodium (70%).Our sequence analysis indicates that Cryptosporidium ,unlike Plasmodium and Toxoplasma ,lacks both mitochondrion and apicoplast genomes.The overall complete-ness of the genome sequence,together with the fact that similar DNA extraction proce-dures used to isolate total genomic DNA from C.parvum efficiently yielded mito-chondrion and apicoplast genomes from Ei-meria sp.and Toxoplasma (6,7),indicates that the absence of organellar genomes was unlikely to have been the result of method-ological error.These conclusions are con-sistent with the absence of nuclear genes for the DNA replication and translation machinery characteristic of mitochondria and apicoplasts,and with the lack of mito-chondrial or apicoplast targeting signals for tRNA synthetases.A number of putative mitochondrial pro-teins were identified,including components of a mitochondrial protein import apparatus,chaperones,uncoupling proteins,and solute translocators (table S1).However,the ge-nome does not encode any Krebs cycle en-zymes,nor the components constituting the mitochondrial complexes I to IV;this finding indicates that the parasite does not rely on complete oxidation and respiratory chains for synthesizing adenosine triphosphate (ATP).Similar to Plasmodium ,no orthologs for the ␥,␦,or εsubunits or the c subunit of the F 0proton channel were detected (whereas all subunits were found for a V-type ATPase).Cryptosporidium ,like Eimeria (8)and Plas-modium ,possesses a pyridine nucleotide tran-shydrogenase integral membrane protein that may couple reduced nicotinamide adenine dinucleotide (NADH)and reduced nico-tinamide adenine dinucleotide phosphate (NADPH)redox to proton translocation across the inner mitochondrial membrane.Unlike Plasmodium ,the parasite has two copies of the pyridine nucleotide transhydrogenase gene.Also present is a likely mitochondrial membrane –associated,cyanide-resistant alter-native oxidase (AOX )that catalyzes the reduction of molecular oxygen by ubiquinol to produce H 2O,but not superoxide or H 2O 2.Several genes were identified as involved in biogenesis of iron-sulfur [Fe-S]complexes with potential mitochondrial targeting signals (e.g.,nifS,nifU,frataxin,and ferredoxin),supporting the presence of a limited electron flux in the mitochondrial remnant (table S2).Our sequence analysis confirms the absence of a plastid genome (7)and,additionally,the loss of plastid-associated metabolic pathways including the type II fatty acid synthases (FASs)and isoprenoid synthetic enzymes thatTable 1.General features of the C.parvum genome and comparison with other single-celled eukaryotes.Values are derived from respective genome project summaries (3,26–28).ND,not determined.FeatureC.parvum P.falciparum S.pombe S.cerevisiae E.cuniculiSize (Mbp)9.122.912.512.5 2.5(G ϩC)content (%)3019.43638.347No.of genes 38075268492957701997Mean gene length (bp)excluding introns 1795228314261424ND Gene density (bp per gene)23824338252820881256Percent coding75.352.657.570.590Genes with introns (%)553.9435ND Intergenic regions (G ϩC)content %23.913.632.435.145Mean length (bp)5661694952515129RNAsNo.of tRNA genes 454317429944No.of 5S rRNA genes 6330100–2003No.of 5.8S ,18S ,and 28S rRNA units 57200–400100–20022Table parison between predicted C.parvum and P.falciparum proteins.FeatureC.parvum P.falciparum *Common †Total predicted proteins380752681883Mitochondrial targeted/encoded 17(0.45%)246(4.7%)15Apicoplast targeted/encoded 0581(11.0%)0var/rif/stevor ‡0236(4.5%)0Annotated as protease §50(1.3%)31(0.59%)27Annotated as transporter 69(1.8%)34(0.65%)34Assigned EC function ¶167(4.4%)389(7.4%)113Hypothetical proteins925(24.3%)3208(60.9%)126*Values indicated for P.falciparum are as reported (3)with the exception of those for proteins annotated as protease or transporter.†TBLASTN hits (e Ͻ–5)between C.parvum and P.falciparum .‡As reported in (3).§Pre-dicted proteins annotated as “protease or peptidase”for C.parvum (CryptoGenome database,)and P.falciparum (PlasmoDB database,).Predicted proteins annotated as “trans-porter,permease of P-type ATPase”for C.parvum (CryptoGenome)and P.falciparum (PlasmoDB).¶Bidirectional BLAST hit (e Ͻ–15)to orthologs with assigned Enzyme Commission (EC)numbers.Does not include EC assignment numbers for protein kinases or protein phosphatases (due to inconsistent annotation across genomes),or DNA polymerases or RNA polymerases,as a result of issues related to subunit inclusion.(For consistency,46proteins were excluded from the reported P.falciparum values.)R E P O R T S16APRIL 2004VOL 304SCIENCE 442 o n O c t o b e r 7, 2009w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o mare otherwise localized to the plastid in other apicomplexans.C.parvum fatty acid biosynthe-sis appears to be cytoplasmic,conducted by a large(8252amino acids)modular type I FAS (9)and possibly by another large enzyme that is related to the multidomain bacterial polyketide synthase(10).Comprehensive screening of the C.parvum genome sequence also did not detect orthologs of Plasmodium nuclear-encoded genes that contain apicoplast-targeting and transit sequences(11).C.parvum metabolism is greatly stream-lined relative to that of Plasmodium,and in certain ways it is reminiscent of that of another obligate eukaryotic parasite,the microsporidian Encephalitozoon.The degeneration of the mi-tochondrion and associated metabolic capabili-ties suggests that the parasite largely relies on glycolysis for energy production.The parasite is capable of uptake and catabolism of mono-sugars(e.g.,glucose and fructose)as well as synthesis,storage,and catabolism of polysac-charides such as trehalose and amylopectin. Like many anaerobic organisms,it economizes ATP through the use of pyrophosphate-dependent phosphofructokinases.The conver-sion of pyruvate to acetyl–coenzyme A(CoA) is catalyzed by an atypical pyruvate-NADPH oxidoreductase(Cp PNO)that contains an N-terminal pyruvate–ferredoxin oxidoreductase (PFO)domain fused with a C-terminal NADPH–cytochrome P450reductase domain (CPR).Such a PFO-CPR fusion has previously been observed only in the euglenozoan protist Euglena gracilis(12).Acetyl-CoA can be con-verted to malonyl-CoA,an important precursor for fatty acid and polyketide biosynthesis.Gly-colysis leads to several possible organic end products,including lactate,acetate,and ethanol. The production of acetate from acetyl-CoA may be economically beneficial to the parasite via coupling with ATP production.Ethanol is potentially produced via two in-dependent pathways:(i)from the combination of pyruvate decarboxylase and alcohol dehy-drogenase,or(ii)from acetyl-CoA by means of a bifunctional dehydrogenase(adhE)with ac-etaldehyde and alcohol dehydrogenase activi-ties;adhE first converts acetyl-CoA to acetal-dehyde and then reduces the latter to ethanol. AdhE predominantly occurs in bacteria but has recently been identified in several protozoans, including vertebrate gut parasites such as Enta-moeba and Giardia(13,14).Adjacent to the adhE gene resides a second gene encoding only the AdhE C-terminal Fe-dependent alcohol de-hydrogenase domain.This gene product may form a multisubunit complex with AdhE,or it may function as an alternative alcohol dehydro-genase that is specific to certain growth condi-tions.C.parvum has a glycerol3-phosphate dehydrogenase similar to those of plants,fungi, and the kinetoplastid Trypanosoma,but(unlike trypanosomes)the parasite lacks an ortholog of glycerol kinase and thus this pathway does not yield glycerol production.In addition to themodular fatty acid synthase(Cp FAS1)andpolyketide synthase homolog(Cp PKS1), C.parvum possesses several fatty acyl–CoA syn-thases and a fatty acyl elongase that may partici-pate in fatty acid metabolism.Further,enzymesfor the metabolism of complex lipids(e.g.,glyc-erolipid and inositol phosphate)were identified inthe genome.Fatty acids are apparently not anenergy source,because enzymes of the fatty acidoxidative pathway are absent,with the exceptionof a3-hydroxyacyl-CoA dehydrogenase.C.parvum purine metabolism is greatlysimplified,retaining only an adenosine ki-nase and enzymes catalyzing conversionsof adenosine5Ј-monophosphate(AMP)toinosine,xanthosine,and guanosine5Ј-monophosphates(IMP,XMP,and GMP).Among these enzymes,IMP dehydrogenase(IMPDH)is phylogenetically related toε-proteobacterial IMPDH and is strikinglydifferent from its counterparts in both thehost and other apicomplexans(15).In con-trast to other apicomplexans such as Toxo-plasma gondii and P.falciparum,no geneencoding hypoxanthine-xanthineguaninephosphoribosyltransferase(HXGPRT)is de-tected,in contrast to a previous report on theactivity of this enzyme in C.parvum sporo-zoites(16).The absence of HXGPRT sug-gests that the parasite may rely solely on asingle enzyme system including IMPDH toproduce GMP from AMP.In contrast to otherapicomplexans,the parasite appears to relyon adenosine for purine salvage,a modelsupported by the identification of an adeno-sine transporter.Unlike other apicomplexansand many parasitic protists that can synthe-size pyrimidines de novo,C.parvum relies onpyrimidine salvage and retains the ability forinterconversions among uridine and cytidine5Ј-monophosphates(UMP and CMP),theirdeoxy forms(dUMP and dCMP),and dAMP,as well as their corresponding di-and triphos-phonucleotides.The parasite has also largelyshed the ability to synthesize amino acids denovo,although it retains the ability to convertselect amino acids,and instead appears torely on amino acid uptake from the host bymeans of a set of at least11amino acidtransporters(table S2).Most of the Cryptosporidium core pro-cesses involved in DNA replication,repair,transcription,and translation conform to thebasic eukaryotic blueprint(2).The transcrip-tional apparatus resembles Plasmodium interms of basal transcription machinery.How-ever,a striking numerical difference is seenin the complements of two RNA bindingdomains,Sm and RRM,between P.falcipa-rum(17and71domains,respectively)and C.parvum(9and51domains).This reductionresults in part from the loss of conservedproteins belonging to the spliceosomal ma-chinery,including all genes encoding Smdomain proteins belonging to the U6spliceo-somal particle,which suggests that this par-ticle activity is degenerate or entirely lost.This reduction in spliceosomal machinery isconsistent with the reduced number of pre-dicted introns in Cryptosporidium(5%)rela-tive to Plasmodium(Ͼ50%).In addition,keycomponents of the small RNA–mediatedposttranscriptional gene silencing system aremissing,such as the RNA-dependent RNApolymerase,Argonaute,and Dicer orthologs;hence,RNA interference–related technolo-gies are unlikely to be of much value intargeted disruption of genes in C.parvum.Cryptosporidium invasion of columnarbrush border epithelial cells has been de-scribed as“intracellular,but extracytoplas-mic,”as the parasite resides on the surface ofthe intestinal epithelium but lies underneaththe host cell membrane.This niche may al-low the parasite to evade immune surveil-lance but take advantage of solute transportacross the host microvillus membrane or theextensively convoluted parasitophorous vac-uole.Indeed,Cryptosporidium has numerousgenes(table S2)encoding families of putativesugar transporters(up to9genes)and aminoacid transporters(11genes).This is in starkcontrast to Plasmodium,which has fewersugar transporters and only one putative ami-no acid transporter(GenBank identificationnumber23612372).As a first step toward identification ofmulti–drug-resistant pumps,the genome se-quence was analyzed for all occurrences ofgenes encoding multitransmembrane proteins.Notable are a set of four paralogous proteinsthat belong to the sbmA family(table S2)thatare involved in the transport of peptide antibi-otics in bacteria.A putative ortholog of thePlasmodium chloroquine resistance–linkedgene Pf CRT(17)was also identified,althoughthe parasite does not possess a food vacuole likethe one seen in Plasmodium.Unlike Plasmodium,C.parvum does notpossess extensive subtelomeric clusters of anti-genically variant proteins(exemplified by thelarge families of var and rif/stevor genes)thatare involved in immune evasion.In contrast,more than20genes were identified that encodemucin-like proteins(18,19)having hallmarksof extensive Thr or Ser stretches suggestive ofglycosylation and signal peptide sequences sug-gesting secretion(table S2).One notable exam-ple is an11,700–amino acid protein with anuninterrupted stretch of308Thr residues(cgd3_720).Although large families of secretedproteins analogous to the Plasmodium multi-gene families were not found,several smallermultigene clusters were observed that encodepredicted secreted proteins,with no detectablesimilarity to proteins from other organisms(Fig.1,A and B).Within this group,at leastfour distinct families appear to have emergedthrough gene expansions specific to the Cryp-R E P O R T S SCIENCE VOL30416APRIL2004443o n O c t o b e r 7 , 2 0 0 9 w w w . s c i e n c e m a g . o r g D o w n l o a d e d f r o mtosporidium clade.These families —SKSR,MEDLE,WYLE,FGLN,and GGC —were named after well-conserved sequence motifs (table S2).Reverse transcription polymerase chain reaction (RT-PCR)expression analysis (20)of one cluster,a locus of seven adjacent CpLSP genes (Fig.1B),shows coexpression during the course of in vitro development (Fig.1C).An additional eight genes were identified that encode proteins having a periodic cysteine structure similar to the Cryptosporidium oocyst wall protein;these eight genes are similarly expressed during the onset of oocyst formation and likely participate in the formation of the coccidian rigid oocyst wall in both Cryptospo-ridium and Toxoplasma (21).Whereas the extracellular proteins described above are of apparent apicomplexan or lineage-specific in-vention,Cryptosporidium possesses many genesencodingsecretedproteinshavinglineage-specific multidomain architectures composed of animal-and bacterial-like extracellular adhe-sive domains (fig.S1).Lineage-specific expansions were ob-served for several proteases (table S2),in-cluding an aspartyl protease (six genes),a subtilisin-like protease,a cryptopain-like cys-teine protease (five genes),and a Plas-modium falcilysin-like (insulin degrading enzyme –like)protease (19genes).Nine of the Cryptosporidium falcilysin genes lack the Zn-chelating “HXXEH ”active site motif and are likely to be catalytically inactive copies that may have been reused for specific protein-protein interactions on the cell sur-face.In contrast to the Plasmodium falcilysin,the Cryptosporidium genes possess signal peptide sequences and are likely trafficked to a secretory pathway.The expansion of this family suggests either that the proteins have distinct cleavage specificities or that their diversity may be related to evasion of a host immune response.Completion of the C.parvum genome se-quence has highlighted the lack of conven-tional drug targets currently pursued for the control and treatment of other parasitic protists.On the basis of molecular and bio-chemical studies and drug screening of other apicomplexans,several putative Cryptospo-ridium metabolic pathways or enzymes have been erroneously proposed to be potential drug targets (22),including the apicoplast and its associated metabolic pathways,the shikimate pathway,the mannitol cycle,the electron transport chain,and HXGPRT.Nonetheless,complete genome sequence analysis identifies a number of classic and novel molecular candidates for drug explora-tion,including numerous plant-like and bacterial-like enzymes (tables S3and S4).Although the C.parvum genome lacks HXGPRT,a potent drug target in other api-complexans,it has only the single pathway dependent on IMPDH to convert AMP to GMP.The bacterial-type IMPDH may be a promising target because it differs substan-tially from that of eukaryotic enzymes (15).Because of the lack of de novo biosynthetic capacity for purines,pyrimidines,and amino acids,C.parvum relies solely on scavenge from the host via a series of transporters,which may be exploited for chemotherapy.C.parvum possesses a bacterial-type thymidine kinase,and the role of this enzyme in pyrim-idine metabolism and its drug target candida-cy should be pursued.The presence of an alternative oxidase,likely targeted to the remnant mitochondrion,gives promise to the study of salicylhydroxamic acid (SHAM),as-cofuranone,and their analogs as inhibitors of energy metabolism in the parasite (23).Cryptosporidium possesses at least 15“plant-like ”enzymes that are either absent in or highly divergent from those typically found in mammals (table S3).Within the glycolytic pathway,the plant-like PPi-PFK has been shown to be a potential target in other parasites including T.gondii ,and PEPCL and PGI ap-pear to be plant-type enzymes in C.parvum .Another example is a trehalose-6-phosphate synthase/phosphatase catalyzing trehalose bio-synthesis from glucose-6-phosphate and uridine diphosphate –glucose.Trehalose may serve as a sugar storage source or may function as an antidesiccant,antioxidant,or protein stability agent in oocysts,playing a role similar to that of mannitol in Eimeria oocysts (24).Orthologs of putative Eimeria mannitol synthesis enzymes were not found.However,two oxidoreductases (table S2)were identified in C.parvum ,one of which belongs to the same families as the plant mannose dehydrogenases (25)and the other to the plant cinnamyl alcohol dehydrogenases.In principle,these enzymes could synthesize protective polyol compounds,and the former enzyme could use host-derived mannose to syn-thesize mannitol.References and Notes1.D.G.Korich et al .,Appl.Environ.Microbiol.56,1423(1990).2.See supportingdata on Science Online.3.M.J.Gardner et al .,Nature 419,498(2002).4.A.T.Bankier et al .,Genome Res.13,1787(2003).5.J.C.Wootton,Comput.Chem.18,269(1994).Fig.1.(A )Schematic showing the chromosomal locations of clusters of potentially secreted proteins.Numbers of adjacent genes are indicated in paren-theses.Arrows indicate direc-tion of clusters containinguni-directional genes (encoded on the same strand);squares indi-cate clusters containingg enes encoded on both strands.Non-paralogous genes are indicated by solid gray squares or direc-tional triangles;SKSR (green triangles),FGLN (red trian-gles),and MEDLE (blue trian-gles)indicate three C.parvum –specific families of paralogous genes predominantly located at telomeres.Insl (yellow tri-angles)indicates an insulinase/falcilysin-like paralogous gene family.Cp LSP (white square)indicates the location of a clus-ter of adjacent large secreted proteins (table S2)that are cotranscriptionally regulated.Identified anchored telomeric repeat sequences are indicated by circles.(B )Schematic show-inga select locus containinga cluster of coexpressed large secreted proteins (Cp LSP).Genes and intergenic regions (regions between identified genes)are drawn to scale at the nucleotide level.The length of the intergenic re-gions is indicated above or be-low the locus.(C )Relative ex-pression levels of CpLSP (red lines)and,as a control,C.parvum Hedgehog-type HINT domain gene (blue line)duringin vitro development,as determined by semiquantitative RT-PCR usingg ene-specific primers correspondingto the seven adjacent g enes within the CpLSP locus as shown in (B).Expression levels from three independent time-course experiments are represented as the ratio of the expression of each gene to that of C.parvum 18S rRNA present in each of the infected samples (20).R E P O R T S16APRIL 2004VOL 304SCIENCE 444 o n O c t o b e r 7, 2009w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o m。
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MultiquarkStatesinaGoldstoneBosonExchangeModel
Fl.Stancu
∗
InstituteofPhysics,B.5,UniversityofLiege,SartTilman,B-4000Liege1,Belgium
Abstract
Wediscussthestabilityofmultiquarksystemscontainingheavyflavours.We
showthattheGoldstonebosonexchangemodelgivesresultsatvariancewith
one-gluon-exchangemodels.
I.INTRODUCTION
Thestudyofexotichadronsformedofmorethanthreequarksand/orantiquarks(q
m
q2[1],thepentaquarksq
4
candudds
∗
E-mailaddress:fstancu@ulg.ac.be
1
wherethespin-dependenttermofthequark-quarkinteractionisdescribedbythechromo-
magneticpartoftheonegluonexchange(OGE)interaction[8]withresultsweobtainedfrom
theGoldstonebosonexchange(GBE)model[9–12].Inthismodelthehyperfinesplittingin
hadronsisduetotheshort-rangepartoftheGoldstonebosonexchangeinteractionbetween
quarks,insteadoftheOGEinteractionofconventionalmodels.TheGBEinteractionis
flavour-dependentanditsmainmeritisthatitreproducesthecorrectorderingofpositive
andnegativeparitystatesinallpartsoftheconsideredspectrum.Moreover,theGBEin-
teractioninducesastrongshort-rangerepulsionintheΛ-Λsystem,whichsuggeststhata
deeplyboundH-baryonshouldnotexist[13].Thisisinagreementwiththehigh-sensitivity
experimentsatBrookhaven[14]wherenoevidenceforHproductionhasbeenfound.
Inthestabilityproblemweareinterestedinthequantity
∆E=E(q
m
qn)representsthemultiquarkenergyandETisthelowestthresholdenergy
fordissociationintotwohadrons:twomesonsfortetraquarks,abaryon+amesonfor
pentaquarksandtwobaryonsforhexaquarks.Anegative∆Esuggeststhepossibilityofa
stablecompactmutiquarksystem.
AccordingtoRef.[9]thereisnomesonexchangeinteractionbetweenquarksandanti-
quarks.Itisassumedthattheq
2m
i
−
(ipi)
2
Vconf(rij)=−
3
2/31,where1isthe3×3unitmatrix.Theinteraction(2)containsγ=π,K,η
andη′meson-exchangetermsandtheformofVγ(rij)isgivenasthesumoftwodistinct
contributions:aYukawa-typepotentialcontainingthemassoftheexchangedmesonanda
short-rangecontributionofoppositesign,theroleofwhichiscrucialinbaryonspectroscopy.
Foragivenmesonγ,theexchangepotentialis
Vγ(r)=g2γ12mimj{θ(r−r0)µ
2
γ
e
−µγr
√
4π=g2ηq4π
=0.67,
g
2
η′q
TABLES
TABLEI.Resultsfor∆E,Eq.(1),forcharmedexotichadrons
.
SystemGBE
c19MeV[15]
c(P=+1)-76MeV[17]
uuds-51MeV[18]
-7.7MeV[20]
OnecanseethattheOGEandtheGBEinteractionspredictcontradictoryresultsfor
thecharmedexoticsystemspresentedhere:whiletheGBEinteractionstabilizesagiven
system,theOGEinteractiondestabilizesitandviceversa.Thefollowingremarksarein
order:
•Astheuudd
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6
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7