8,912 research outputs found
LEP, SLC and the Standard Model
The period 1989-2000 provided a huge yield of precise electroweak data from
the LEP and SLC experiments. Many analyses of these data are now complete, but
others, particularly of the full LEP-2 data samples, continue. The main
electroweak physics results from these data are summarised, and stringent tests
of the Standard Model are made with the combined samples. The direct search for
the missing link of the Standard Model, the Higgs boson, is also briefly
reviewed.Comment: Invited talk at the XXXth SLAC Summer Institute Topical Conference,
Stanford, California, USA, August 2002 (SSI02-TW05) 24 pages, LaTeX, 25 eps
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Precise Electroweak Results from LEP2
Precise electroweak results from LEP2 are reviewed.Comment: 16 pages, 10 figures, to appear in Proceedings of XIX International
Symposium on Lepton and Photon Interactions at High Energies (LP'99
Context-related acoustic variation in male fallow deer (Dama dama) groans
While social and behavioural contexts are known to affect the acoustic structure of vocal signals in several mammal species, few studies have investigated context-related acoustic variation during inter-sexual advertisement and/or intra-sexual competition. Here we recorded male fallow deer groans during the breeding season and investigated how key acoustic parameters (fundamental frequency and formant frequencies) vary as a function of the social context in which they are produced. We found that in the presence of females, male fallow deer produced groans with higher mean fundamental frequency when vocal males were also present than they did when no vocal males were in close vicinity. We attribute this to the increased arousal state typically associated with this context. In addition, groan minimum formant frequency spacing was slightly, but significantly lower (indicating marginally more extended vocal tracts) when males were alone than when potential mates and/or competitors were nearby. This indicates that, contrary to our predictions, male fallow deer do not exaggerate the acoustic impression of their body size by further lowering their formant frequencies in the presence of potential mating partners and competitors. Furthermore, since the magnitude of the variation in groan minimum formant frequency spacing remains small compared to documented inter-individual differences, our findings are consistent with the hypothesis that formants are reliable static cues to body size during intra- and inter-sexual advertisement that do not concurrently encode dynamic motivation-related informatio
Pneumatic system for controlling and actuating pneumatic cyclic devices
Pneumatic system for cyclic control of fluid flow in pneumatic devic
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Facilitation of transmitter release at squid synapses
Facilitation is shown to decay as a compound exponential with two
time constants (T1, T2) at both giant and non-giant synapses in squid steilate ganglia
bathed in solutions having low extracellular calcium concentrations ([Ca++]o).
Maximum values of facilitation (F~) were significantly larger, and T1 was significantly
smaller in giant than non-giant synapses. Decreases in [Ca++]o or increases in
[Mn++]o had variable effects on T1 and F1, whereas decreases in temperature
increased T~ but had insignificant effects on/'1. The growth of facilitation during
short trains of equal interval stimuli was adequately predicted by the linear
summation model developed by Mallart and Martin (1967.J. Physiol. (Lond.). 193:
676-694) for frog neuromuscular junctions. This result suggests that the underlying
mechanisms of facilitation are similar in squid and other synapses which release
many transmitter quanta.This work was supported by National Science Foundation research grant GB-36949, National
Research Council (Canada) and Grass Fellowships to Dr. Charlton, and a National Institutes of
Health career award (NS-00070) to Dr. Bittner.Neuroscienc
Koalas use a novel vocal organ to produce unusually low-pitched mating calls
SummaryDuring the breeding season, male koalas produce ‘bellow’ vocalisations that are characterised by a continuous series of inhalation and exhalation sections, and an extremely low fundamental frequency (the main acoustic correlate of perceived pitch) [1]. Remarkably, the fundamental frequency (F0) of bellow inhalation sections averages 27.1 Hz (range: 9.8–61.5 Hz [1]), which is 20 times lower than would be expected for an animal weighing 8 kg [2] and more typical of an animal the size of an elephant (Supplemental figure S1A). Here, we demonstrate that koalas use a novel vocal organ to produce their unusually low-pitched mating calls
Spool valve cycles at controlled frequency
Spool valve accurately controls the cycle of a pneumatically-actuated system over long periods. Regulation of pressure from the external source, positioning of the adjusting plugs, and magnet selection, together afford wide variation in cyclic timing and speed of closure in either direction
No preference in female sika deer for conspecific over heterospecific male sexual calls in a mate choice context
Mating signals can be used both in contexts of species recognition and mate quality assessment. This study examines species recognition abilities in oestrous females presented with male mating calls from both conspecifics and closely related allopatric heterospecifics. Red deer and sika deer are naturally allopatric polygynous species capable of hybridization during sympatry. Male mating calls are sexually selected and differ greatly between species. Previous work indicated that most but not all oestrous red deer hinds prefer male mating calls from conspecifics over heterospecific sika deer. Using two-speaker playback experiments, we extend this examination by measuring the preference responses of oestrous sika deer hinds to these stimuli. We predicted that oestrous sika deer hinds will show little flexibility in behavioural responses and prefer conspecific calls over heterospecific calls, similar to those of red deer hinds. In contrast, sika deer hinds showed high levels of flexibility and no difference in overall preference behaviours, suggesting that vocal behaviour does not provide a solid barrier to hybridization in this species. The asymmetry in heterospecific preference responses between these species is discussed in relation to possible causation and hybridization patterns observed in free-ranging populations
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