Showing 2001 - 2010 of 2040 Items
Date: 2015-05-20
Creator: Jay J. Falk
Hannah M. Ter Hofstede
Patricia L. Jones
Marjorie M. Dixon
Paul A., Faure
Elisabeth K.V. Kalko
Rachel A. Page
Access: Open access
- Many predators and parasites eavesdrop on the communication signals of their prey. Eavesdropping is typically studied as dyadic predator-prey species interactions; yet in nature, most predators target multiple prey species and most prey must evade multiple predator species. The impact of predator communities on prey signal evolution is not well understood. Predators could converge in their preferences for conspicuous signal properties, generating competition among predators and natural selection on particular prey signal features. Alternatively, predator species could vary in their preferences for prey signal properties, resulting in sensory-based niche partitioning of prey resources. In the Neotropics, many substrate-gleaning bats use the mate-attraction songs of male katydids to locate them as prey. We studied mechanisms of niche partitioning in four substrate- gleaning bat species and found they are similar in morphology, echolocation signal design and prey-handling ability, but each species preferred different acoustic features of male song in 12 sympatric katydid species. This divergence in predator preference probably contributes to the coexistence of many substrate-gleaning bat species in the Neotropics, and the substantial diversity in the mate-attraction signals of katydids. Our results provide insight into how multiple eavesdropping predator species might influence prey signal evolution through sensory-based niche partitioning.
Date: 2013-10-23
Creator: Patricia L. Jones
Michael J. Ryan
Victoria Flores
Rachel A. Page
Access: Open access
- Animals can use different sources of information when making decisions. Foraging animals often have access to both self-acquired and socially acquired information about prey. The fringe-lipped bat, Trachops cirrhosus, hunts frogs by approaching the calls that frogs produce to attract mates.We examined howthe reliability of self-acquired prey cues affects social learning of novel prey cues. We trained bats to associate an artificial acoustic cue (mobile phone ringtone) with food rewards. Bats were assigned to treatments in which the trained cue was either an unreliable indicator of reward (rewarded 50% of the presentations) or a reliable indicator (rewarded 100% of the presentations), and they were exposed to a conspecific tutor foraging on a reliable (rewarded 100%) novel cue or to the novel cue with no tutor. Bats whose trained cue was unreliable and who had a tutor were significantly more likely to preferentially approach the novel cue when compared with bats whose trained cue was reliable, and to bats that had no tutor. Reliability of self-acquired prey cues therefore affects social learning of novel prey cues by frog-eating bats. Examining when animals use social information to learn about novel prey is key to understanding the social transmission of foraging innovations. © 2013 The Author(s) Published by the Royal Society.
Date: 2009-07-28
Creator: Ruth Griffin
Anne Sustar
Marianne Bonvin
Richard Binari
Alberto, del Valle Rodriguez
Amber M. Hohl
Jack R. Bateman
Christians Villalta
Elleard Heffern
Didier Grunwald
Chris Bakal
Claude Desplan
Gerold Schubiger
C. Ting Wu
Norbert Perrimon
Access: Open access
- In Drosophila melanogaster, widely used mitotic recombination-based strategies generate mosaic flies with positive readout for only one daughter cell after division. To differentially label both daughter cells, we developed the twin spot generator (TSG) technique, which through mitotic recombination generates green and red twin spots that are detectable after the first cell division as single cells. We propose wide applications of TSG to lineage and genetic mosaic studies.
Date: 2003-08-01
Creator: Mark Battle
Michael Bender
Melissa B. Hendricks
David T. Ho
Robert, Mika
Galen McKinley
Song Miao Fan
Tegan Blaine
Ralph F. Keeling
Access: Open access
- The Ar/N2 ratio of air measured at 6 globally distributed sites shows annual cycles with amplitudes of 12 to 37 parts in 106. Summertime maxima reflect the atmospheric Ar enrichment driven by seasonal warming and degassing of the oceans. Paired models of air-sea heat fluxes and atmospheric tracer transport predict seasonal cycles in the Ar/N2 ratio that agree with observations, within uncertainties.
Date: 1999-07-01
Creator: R. L. Langenfelds
R. J. Francey
L. P. Steele
M. Battle
R. F., Keeling
W. F. Budd
Access: Open access
- O2/N2 is measured in the Cape Grim Air Archive (CGAA), a suite of tanks filled with background air at Cape Grim, Tasmania (40.7°S, 144.8°E) between April 1978 and January 1997. Derived trends are compared with published O2/N2 records and assessed against limits on interannual variability of net terrestrial exchanges imposed by trends of δ13C in CO2. Two old samples from 1978 and 1987 and eight from 1996/97 survive critical selection criteria and give a mean 19-year trend in δ(O2/N2) of -16.7 ± 0.5 per meg yr-1, implying net storage of +2.3 ± 0.7 GtC (1015 g carbon) yr-1 of fossil fuel CO2 in the oceans and +0.2 ± 0.9 GtC yr-1 in the terrestrial biosphere. The uptake terms are consistent for both O2/N2 and δ13C tracers if the mean 13C isotopic disequilibrium flux, combining terrestrial and oceanic contributions, is 93 ± 15 GtC ‰ yr-1. Copyright 1999 by the American Geophysical Union.
Date: 1999-01-01
Creator: Zachary Wills
Jack Bateman
Christopher A. Korey
Allen Comer
David, Van Vactor
Access: Open access
- Genetic analysis of growth cone guidance choice points in Drosophila identified neuronal receptor protein tyrosine phosphatases (RPTPs) as key determinants of axon pathfinding behavior. We now demonstrate that the Drosophila Abl tyrosine kinase functions in the intersegmental nerve b (ISNb) motor choice point pathway as an antagonist of the RPTP Dlar. The function of Abl in this pathway is dependent on an intact catalytic domain. We also show that the Abl phosphoprotein substrate Enabled (Ena) is required for choice point navigation. Both Abl and Ena proteins associate with the Dlar cytoplasmic domain and serve as substrates for Dlar in vitro, suggesting that they play a direct role in the Dlar pathway. These data suggest that Dlar, Abl, and Ena define a phosphorylation state-dependent switch that controls growth cone behavior by transmitting signals at the cell surface to the actin cytoskeleton.
Date: 1995-01-01
Creator: B. Barish
M. Chadha
S. Chan
D. F. Cowen
G., Eigen
J. S. Miller
C. O'Grady
J. Urheim
A. J. Weinstein
D. Acosta
M. Athanas
G. Masek
H. P. Paar
J. Gronberg
R. Kutschke
S. Menary
R. J. Morrison
S. Nakanishi
H. N. Nelson
T. K. Nelson
C. Qiao
J. D. Richman
A. Ryd
H. Tajima
D. Sperka
M. S. Witherell
M. Procario
R. Balest
K. Cho
M. Daoudi
W. T. Ford
Access: Open access
- We study the exclusive semileptonic B meson decays B-→D*0l-ν̄ and B̄0→D*+l-ν̄ using data collected with the CLEO II detector at the Cornell Electron-positron Storage Ring (CESR). We present measurements of the branching fractions scrB(B̄0→D*+l-ν̄)= (0.5/f00)[4.49±0.32(stat.)±0.39 (syst.)]% and scrB(B-→D*0l-(ν̄)= (0.5/f+-)[5.13±0.54 (stat) ±0.64 (syst)]%, where f00 and f+- are the neutral and charged B meson production fractions at the Υ(4S) resonance, respectively. Assuming isospin invariance and taking the ratio of charged to neutral B meson lifetimes measured at higher energy machines, we determine the ratio f+-/f00=1.04±0.13 (stat) ±0.12 (syst) ±0.10 (lifetime); further assuming f+-+f00=1 we also determine the partial width Γ(B̄→D*lν̄)=[29.9±1.9 (stat) ±2.7 (syst.) ±2.0 (lifetime)] ns-1 (independent of f+-/f00). From this partial width we calculate B̄→D*lν̄ branching fractions that do not depend on f+-/f00 or the individual B lifetimes, but only on the charged to neutral B lifetime ratio. The product of the CKM matrix element -Vcb- times the normalization of the decay form factor at the point of no recoil of the D* meson, scrF(y=1), is determined from a linear fit to the combined differential decay rate of the exclusive B̄→D*lν̄ decays: -Vcb-scrF(1)=0.0351±0.0019 (stat) ±0.0018 (syst) ±0.0008 (lifetime). The value for -Vcb- is extracted using theoretical calculations of the form factor normalization. © 1995 The American Physical Society.
Date: 1994-01-01
Creator: M. Battle
J. Ernst
Y. Kwon
S. Roberts
E. H., Thorndike
C. H. Wang
J. Dominick
M. Lambrecht
S. Sanghera
V. Shelkov
T. Skwarnicki
R. Stroynowski
I. Volobouev
G. Wei
P. Zadorozhny
M. Artuso
M. Goldberg
D. He
N. Horwitz
R. Kennett
R. Mountain
G. C. Moneti
F. Muheim
Y. Muheim
S. Playfer
Y. Rozen
S. Stone
M. Thulasidas
G. Vasseur
G. Zhu
J. Bartelt
Access: Open access
- Branching ratios for the dominant Cabibbo-suppressed decays of the τ lepton have been measured by CLEO II in e+e- annihilation at the Cornell Electron Storage Ring (s∼10.6 GeV) using kaons with momenta below 0.7 GeV/c. The inclusive branching ratio into one charged kaon is (1.60 ± 0.12 ± 0.19)%. For the exclusive decays, B(τ-→K-ντ)=(0.66±0.07±0.09)%, B(τ-→K-π0ντ)=(0.51±0.10±0.07)%, and, based on three events, B(τ-→K-2π0ντ)<0.3% at the 90% confidence level. These represent significant improvements over previous results. B(τ-→K-π0ντ) is measured for the first time with exclusive π0 reconstruction. © 1994 The American Physical Society.
Date: 1993-01-01
Creator: J. Bartelt
S. E. Csorna
Z. Egyed
V. Jain
D. S., Akerib
B. Barish
M. Chadha
S. Chan
D. F. Cowen
G. Eigen
J. S. Miller
C. O'Grady
J. Urheim
A. J. Weinstein
D. Acosta
M. Athanas
G. Masek
H. Paar
M. Sivertz
A. Bean
J. Gronberg
R. Kutschke
S. Menary
R. J. Morrison
S. Nakanishi
H. N. Nelson
T. K. Nelson
J. D. Richman
A. Ryd
H. Tajima
D. Schmidt
Access: Open access
- Using the CLEO II detector and a sample of 955 000 Υ(4S) decays we have confirmed charmless semileptonic decays of B mesons. In the momentum interval 2.3-2.6 GeV/c we observe an excess of 107±15±11 leptons, which we attribute to b→ulν. This result yields a model-dependent range of values for Vub/Vcb that is lower than has been obtained in previous studies. For the inclusive spectator model of Altarelli et al. we find Vub/Vcb=0.076±0.008. Models that describe b→ulν with a limited set of exclusive final states give Vub/Vcb=0.06-0.10. © 1993 The American Physical Society.
Date: 1993-01-01
Creator: A. Bean
J. Gronberg
R. Kutschke
S. Menary
R. J., Morrison
H. Nelson
J. Richman
H. Tajima
D. Schmidt
D. Sperka
M. Witherell
M. Procario
S. Yang
M. Daoudi
W. T. Ford
D. R. Johnson
K. Lingel
M. Lohner
P. Rankin
J. G. Smith
J. P. Alexander
C. Bebek
K. Berkelman
D. Besson
T. E. Browder
D. G. Cassel
D. M. Coffman
P. S. Drell
R. Ehrlich
R. S. Galik
M. Garcia-Sciveres
Access: Open access
- A search for the lepton mumber violating decay of the τ lepton to the γμ final state has been performed with the CLEO II detector at the Cornell e+e- storage ring CESR. In a data sample that corresponds to an integrated luminosity of 1.55 fb-1, we observe no candidates in the signal region. We thus determine an upper limit of B(τ-→γμ-)<4. 2×10-6 at 90% confidence level. © 1993 The American Physical Society.