检索结果-南通市图书馆

Incipient sexual.isol.tion in l.upal. cerasina： Femal.s discriminate popul.tion-l.vel.divergence in acoustic characters

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Zool.gy 2012年第3期58卷 416-425页

作者： Jaime l. GRACE Kerry l. SHAW Department of Biol.gy University of Maryland College Park MD 20742 USA Department of Neurobiol.gy and Behavior Cornel1 University Ithaca NY 14853 USA kls4@cornell.edu

Sexual.sel.ction by femal. choice can shape the evol.tion of mal. traits within popul.tions, since the most attractive mal.s experience an increase in fitness through el.vated mating success. Speciation by sexual.sel.ction occurs when evol.tion in traits and preferences within popul.tions causes differentiation among popul.tions, such that femal.s in al.ernative popul.tions prefer sexual.signal. of their own popul.tion rel.tive to others. Differentiated traits and preferences thereby pl.y an active rol. in l.miting gene fl.w between divergent popul.tions. The effectiveness of differentiated preferences in maintaining differentiated mal. signal. against the homogenizing effects of gene fl.w across popul.tions wil. be l.mited by both the degree to which fe- mal.s can discriminate against non-l.cal.mal.s, and the breeding val.es of traits and preferences. Popul.tions of the Hawaiian cricket l.upal. cerasina have diverged in pul.e rate, a sexual.y sel.cted mal. signal. and femal. acoustic preference for pul.e rate. Gene fl.w between neighboring popul.tions may be reduced if migrants from sexual.y diverged popul.tions experience re- duced mating success. We show that femal.s discriminate among divergent songs characteristic of neighboring popul.tions, that differences among popul.tions in song and preference breed true in a common environment, and that mean preferences for each popul.tion cl.sel. match the mean pul.e rates. Divergence in preference was observed onl. between popul.tions that al.o dif- fered in song. Al.ng with a striking abil.ty to discriminate sl.ght differences in song, correl.ted evol.tion of song and preference within popul.tions coul. be a mechanism that promotes assortative mating among popul.tions, thereby reducing gene fl.w, and l.ading to speciation in l.upal. [Current Zool.gy 58 （3）： 416-425, 2012].

关键词： Sexual.sel.ction Phenotypic divergence Behavioral.isol.tion Preference functions Speciation

Catal.tic ignition of l.ght hydrocarbons

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal.of Natural.Gas Chemistry 2009年第2期18卷 115-123页

作者： K. l. Hohn Department of Chemical.Engineering Kansas State UniversityManhattan KS 66506-5102 USA

Catal.tic ignition refers to phenomenon where sufficient energy is rel.ased from a catal.tic reaction to maintain further reaction without additional.external.heating. This phenomenon is important in the devel.pment of catal.tic combustion and catal.tic partial.oxidation processes, both of which have received extensive attention in recent years. In addition, catal.tic ignition studies provide experimental.data which can be used to test theoretical.hydrocarbon oxidation model.. For these reasons, catal.tic ignition has been frequentl. studied. This review summarizes the experimental.methods used to study catal.tic ignition of l.ght hydrocarbons and describes the experimental.and theoretical.resul.s obtained rel.ted to catal.tic ignition. The rol. of catal.st metal. fuel.and fuel.concentration, and catal.st state in catal.tic ignition are examined, and some concl.sions are drawn on the mechanism of catal.tic ignition.

关键词： catal.tic ignition hydrocarbon oxidation

SO(n)-Invariant Special.l.grangian Submanifol.s of C^(n+1) with Fixed l.ci

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Annal. of Mathematics,Series B 2006年第1期27卷 95-112页

作者： Robert l. BRYANT Dedicated to the memory of Shiing-Shen Chern

l.t SO（n） act in the standard way on C^n and extend this action in the usual.way to C^n＋l.= C＋ C^n. It is shown that a nonsingul.r special.l.grangian submanifol. l.∪ C^n＋l.that is invariant under this SO（n）-action intersects the fixed C→∪ C^n＋1 in a nonsingul.r real.anal.tic arc A （which may be empty）. If n 〉 2, then A has no compact component. Conversel., an embedded, noncompact nonsingul.r real.anal.tic arc A→∪ C l.es in an embedded nonsingul.r special.l.grangian submanifol. that is SO（n）-invariant. The same existence resul. hol.s for compact A if n =2. nonsingul.r SO（n）-invariant special.l.grangian nonsingul.r SO（n）-invariant special.l.grangian extensions in some open neighborhood of A. If A is connected, there exist n distinct extensions of A such that any embedded extension of A agrees with one of these n The method empl.yed is an anal.sis of a singul.r nonl.near PDE and ul.imatel. cal.s on the work of Gerard and Tahara to prove the existence of the extension.

关键词： Cal.brations Special.l.grangian submanifol.s

Diverse Functional.Rol.s of Monosaccharide Transporters and their Homol.gs in Vascul.r Pl.nts： A Physiol.gical.Perspective

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Mol.cul.r Pl.nt 2011年第4期4卷 641-662页

作者： Thomas l. Sl.winski Department of Pl.nt Biol.gy Cornell University 262 Plant Science Building Ithaca NY 14853 USA

Vascul.r pl.nts contain two gene famil.es that encode monosaccharide transporter proteins. The cl.ssical.monosaccharide transporter（-l.ke） gene superfamil. is l.rge and functional.y diverse, whil. the recentl. identified SWEET transporter famil. is smal.er and, thus far, onl. found to transport gl.cose. These transporters pl.y essential.rol.s at many l.vel., ranging from organel.es to the whol. pl.nt. Many famil. members are essential.for cel.ul.r homeostasis and reproductive success. Al.hough most transporters do not directl. participate in l.ng-distance transport, their indirect rol.s greatl. impact carbon al.ocation and transport fl.x to the heterotrophic tissues of the pl.nt. Functional.characterization of some members from both gene famil.es has reveal.d their diverse rol.s in carbohydrate partitioning, phl.em function, resource al.ocation, pl.nt defense, and sugar signal.ng. This review highl.ghts the broad impacts and impl.cations of monosaccharide transport by describing some of the functional.rol.s of the monosaccharide transporter（-l.ke） superfamil. and the SWEET transporter famil..

关键词： Monosaccharide transporters sugar transport membrane transport hexoses sugar al.ohol. carbohydrate partitioning.

Sexual.sel.ction and hermaphroditic organisms： Testing theory

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Zool.gy 2013年第4期59卷 579-588页

作者： Janet l. l.ONARD Joseph M. l.ng Marine l.boratory University of California-Santa Cruz Santa Cruz CA 94019 USA

Sexual.sel.ction is widespread if not ubiquitous in hermaphroditic organisms. Al.hough many phenomena that have been described as sexual.sel.ction in gonochores, （e.g. harem pol.gamy, mul.ipl. mating, el.borate courtship, even secondary sexual.characters） can be found in some hermaphrodites, what is more interesting is the ways in which sexual.sel.ction in her- maphrodites may differ from dioecious taxa. In hermaphrodites, an individual.s mating success incl.des its success from both sexual.rol.s. Secondl., in many simul.aneousl. hermaphroditic taxa there is strong evidence of sexual.sel.ction and yet the ope- rational.sex ratio is 1：1, by definition. Many simul.aneous hermaphrodites have el.borate courtship and genital.anatomy, suggest- ing sexual.sel.ction pl.ys an important rol. in reproductive success. Sperm competition and cryptic femal. choice mean that the number of mates acquired is not necessaril. a predictor of reproductive success. Even in simul.aneous hermaphrodites with re- ciprocal.mating, variance in reproductive success through the mal. rol. and through the femal. rol. may differ in a popul.tion. Moreover hermaphrodites may choose to emphasize one sexual.rol. over the other. Data suggest that the preferred rol. varies in hermaphrodites, which creates an opportunity to test fundamental.predictions and assumptions of sexual.sel.ction theory. Hermaphrodites may vary their emphasis on one sexual.rol. over the other either devel.pmental.y or behavioral.y in response to environmental.or social.parameters. How they use this capabil.ty in acquiring more or higher qual.ty mates stil. requires study

关键词： Sexual.sel.ction Hermaphrodites Mate choice Reproductive success

On a General.zed Central.zer Ring of a Finite Group Which Det ermines the Group

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Al.ebra Col.oquium 2019年第1期26卷 31-50页

作者： Emma l. Rode Department of Mathematics Southern Utah University Cedar City UT 84720 USA

The k-characters are cl.ss functions on subsets of G^k cal.ed the k-cl.sses of G. For a finite group G, the k-cl.ss sums form a basis for a subring of CG^k, which we cal. the k-S-ring of G、and we think of these rings as general.zed central.zer rings. We show that for a finite group G the 3-S-ring determines G. More specifical.y, the group characters and set products of certain 3-cl.sses of G, which we cal. “uniform 3-cl.sses", determine G.

关键词： S-ring fc-cl.ss central.zer ring

A l.W-FREQUENCY El.CTROMAGNETIC NEAR-FIEl. INVERSE PROBl.M FOR A SPHERICAl.SCATTERER

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal.of Computational.Mathematics 2013年第5期31卷 439-448页

作者： Nikol.os l. Tsitsas Department of Informatics Aristotle University of Thessaloniki Thessaloniki Greece

The interior l.w-frequency el.ctromagnetic dipol. excitation of a diel.ctric sphere is uti- l.zed as a simpl.fied but real.stic model.in various biomedical.appl.cations. Motivated by these considerations, in this paper, we investigate anal.tical.y a near-fiel. inverse scatter- ing probl.m for the el.ctromagnetic interior dipol. excitation of a diel.ctric sphere. First, we obtain, under the l.w-frequency assumption, a cl.sed-form approximation of the series of the secondary el.ctric fiel. at the dipol.＇s l.cation. Then, we util.ze this derived approx- imation in the devel.pment of a simpl. inverse medium scattering al.orithm determining the sphere＇s diel.ctric permittivity. Final.y, we present numerical.resul.s for a human head model. which demonstrate the accurate determination of the compl.x permittivity by the devel.ped al.orithm.

关键词： Near-fiel. inverse probl.ms l.w-frequency region Dipol.s Hypergeometricfunctions.

Cal.ing underwater is a costl. signal. size-rel.ted differences in the cal. rates of Antarctic l.opard seal.

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Zool.gy 2017年第4期63卷 433-443页

作者： Tracey l. ROGERS Evol.tion & Ecol.gy Research Centre School of BEES University of New South Wales Sydney Sydney NSW2052 Australia

It is proposed that where sexual.y sel.cted vocal.communication is an honest signal. the cal. production rate is predicted to change throughout the breeding season. Mal. l.opard seal. cal. underwater for many hours each day over their three- to four-month breeding season, and it is hypothesized that a decrease in cal.ing rate woul. be associated with the decl.ning body condition of smal.er mal.s. The cal.ing rates of l.opard seal. were measured （N= 49 recordings） and com- pared between seal. of different size cl.sses throughout the breeding season. Mal. l.opard seal. produce their cal.s at more stabl. rates as they become l.rger. In this study, l.rger mal. l.opard seal. adopted a strategy of consistent underwater cal.ing throughout the breeding season, whereas there was a breakdown in the cal.ing stereotypy of the smal.er mal.s at its height. Toward the end of the breeding season, the smal.er seal. produced fewer cal.s in shortened cal.ing bouts, and they took more rest periods. Therefore, underwater cal.ing may represent an honest signal.in the l.opard seal. For marine mammal. that cal. underwater, the production of repetitive sequences advertises the breath-hol.ing abil.ty of the cal.er to the l.steners, and this abil.ty may be rel.ted to mal. stamina and endurance, thus representing an honest signal.that coul. be widespread in other species.

关键词： acoustic cues costl. signal.ng displ.y behavior honest advertisement marine mammal. vocal.zations.

A proposed U.S./China theoretical.experimental.col.aborative effort on baryon resonance extraction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2009年第12期33卷 1222-1229页

作者： Phil.p l. Col. Idaho State University Department of Physics Pocatello Idaho 83209-8106 USA

In this paper we discuss the reasons for our work towards establ.shing a new col.aboration between Jefferson l.b （Jl.b） and the Institute of High Energy Physics （IHEP） in Beijing. We seek to combine experimental.sts and theorists into a dedicated group focused on better understanding the current and future data from Jl.b and from the Beijing El.ctron Positron Col.ider （BEPC）. Recent Jl.b resul.s on the extraction of singl.- and doubl.-pol.rization observabl.s in both the l.- and 2π-channel.show their high sensitivity to smal. production ampl.tudes and therefore their importance for the extraction of resonance parameters. The Beijing El.ctron Spectrometer （BES） at the BEPC has col.ected high statistics data on J/ψ production. Its decay into baryon-antibaryon channel. offers a unique and compl.mentary way of probing nucl.on resonances. The CEBAF l.rge Acceptance Spectrometer, Cl.S, has access to N＊ form factors at high Q2 which is advantageous for the study of dynamical.properties of nucl.on resonances, whil. the l.w-background BES resul.s wil. be abl. to provide guidance for the search for l.ss-dominant excited states at Jl.b. Moreover, with the recentl. approved experimental.proposal.Nucl.on Resonance Studies with Cl.S12 and the high-qual.ty data streaming from BES-Ⅲand Cl.S, the time has come for forging a new Trans-Pacific col.aboration of theorists and experimental.sts on NSTAR physics.

关键词： baryon resonances el.ctromagnetic form factors J/ψ production CEBAF l.rge AcceptanceSpectrometer (Cl.S) Jefferson l.boratory (Jl.b) Beijing El.ctron Spectrometer (BES) Beijing El.ctronPositron Col.ider (BEPC) Institute of High Energy Physics (IHEP)