5,228 research outputs found
USE OF INHALANT ANESTHETICS IN THREE SNAKE SPECIES
Different snake species respond differently to various anesthetic agents. Hence, an anesthetic procedure developed for one species cannot necessarily be safely transferred to another species. The goal of this paper is to summarize our experience using inhalant anesthetics on three snake species, including both procedures that were successful and those we found to be less satisfactory. We found isoflurane delivered with a precision vaporizer to be the best agent to anesthetize black rat snakes (Elaphe o. obsoleta). Sex and mass did not seem to affect induction times in black rat snakes, but larger female rat snakes recovered faster from anesthesia than smaller females. Halothane delivered in the open method provided consistent anesthesia in northern water snakes (Nerodia s. sipedon), although it caused some mortality and should not be used on debilitated patients. Halothane delivered with a precision vaporizer may be used to anesthetize eastern massasauga rattlesnakes (Sistrurus c. catenatus). However, care must be taken to prevent mortality resulting from anesthetic overdose. Sex and mass had no effect on induction and recovery times in the rattlesnakes, but stressed animals require longer induction and recovery times
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Direct Laser Fabrication of a Gas Turbine Engine Component - Microstructure and Properties - Part I
This paper presents the development of a new technique for the production of abrasive
turbine blade tips by direct laser processing. This superalloy cermet component is an integral part
of the low pressure turbine sealing system in a demonstrator engine. Direct laser fabrication of
this component fiom a bed a loose powder results in significant cost savings and improved
performance over the currently employed production technique. The technology has been
demonstrated by fabricating a prototype lot of 100 blade tips, which will be subjected to an engine
test. This is the first instance of a direct fabrication method applied to the production of functional
engine hardware. This research was funded by the United States Air Force contract F33615-94-
C-2424 titled "Affordable Turbine Blade Tips".Mechanical Engineerin
Shorter fixation durations for up-directed saccades during saccadic exploration: A meta-analysis
Utilizing 23 datasets, we report a meta-analysis of an asymmetry in presaccadic fixation durations for saccades directed above and below eye fixation during saccadic exploration. For inclusion in the meta-analysis, saccadic exploration of complex visual displays had to have been made without gaze-contingent manipulations. Effect sizes for the asymmetry were quantified as Hedge’s g. Pooled effect sizes indicated significant asymmetries such that during saccadic exploration in a variety of tasks, presaccadic fixation durations for saccades directed into the upper visual field were reliably shorter than presaccadic fixation durations for saccades into the lower visual field. It is contended that the asymmetry is robust and important for efforts aimed at modelling when a saccade is initiated as a function of ensuing saccade direction
Black p-Branes versus black holes in non-asymptotically flat Einstein-Yang-Mills theory
We present a class of non-asymptotically flat (NAF) charged black p-branes
(BpB) with p-compact dimensions in higher dimensional Einstein-Yang-Mills
theory. Asymptotically the NAF structure manifests itself as an anti-de-sitter
spacetime. We determine the total mass / energy enclosed in a thin-shell
located outside the event horizon. By comparing the entropies of BpB with those
of black holes in same dimensions we derive transition criteria between the two
types of black objects. Given certain conditions satisfied our analysis shows
that BpB can be considered excited states of black holes. An event horizon
versus charge square plot \ for the BpB reveals such a
transition where is related to the horizon radius of the black
hole (BH) both with the common charge Comment: 10 pages, 1 figure, updated version. Final version to be published in
EPJ
An ALMA Constraint on the GSC 6214-210 B Circum-Substellar Accretion Disk Mass
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations
of GSC 6214-210 A and B, a solar-mass member of the 5-10 Myr Upper Scorpius
association with a 15 2 Mjup companion orbiting at 330 AU
(2.2"). Previous photometry and spectroscopy spanning 0.3-5 m revealed
optical and thermal excess as well as strong H and Pa~ emission
originating from a circum-substellar accretion disk around GSC 6214-210 B,
making it the lowest mass companion with unambiguous evidence of a subdisk.
Despite ALMA's unprecedented sensitivity and angular resolution, neither
component was detected in our 880 m (341 GHz) continuum observations down
to a 3- limit of 0.22 mJy/beam. The corresponding constraints on the
dust mass and total mass are <0.15 Mearth and <0.05 Mjup, respectively, or
<0.003% and <0.3% of the mass of GSC 6214-210 B itself assuming a 100:1
gas-to-dust ratio and characteristic dust temperature of 10-20 K. If the host
star possesses a putative circum-stellar disk then at most it is a meager
0.0015% of the primary mass, implying that giant planet formation has certainly
ceased in this system. Considering these limits and its current accretion rate,
GSC 6214-210 B appears to be at the end stages of assembly and is not expected
to gain any appreciable mass over the next few Myr.Comment: Accepted to ApJ
Neighborhood size-effects shape growing population dynamics in evolutionary public goods games
An evolutionary game emerges when a subset of individuals incur costs to provide benefits to all individuals. Public goods games (PGG) cover the essence of such dilemmas in which cooperators are prone to exploitation by defectors. We model the population dynamics of a non-linear\ua0PGG and consider density-dependence on the global level, while the game occurs within local neighborhoods. At low cooperation, increases in the public good provide increasing returns. At high cooperation, increases provide diminishing returns. This mechanism leads to diverse evolutionarily stable strategies, including monomorphic and polymorphic populations, and neighborhood-size-driven state changes, resulting in hysteresis between equilibria. Stochastic or strategy-dependent variations in neighborhood sizes favor coexistence by destabilizing monomorphic states. We integrate our model with experiments of cancer cell growth and confirm that our framework describes PGG dynamics observed in cellular populations. Our findings advance the understanding of how neighborhood-size effects in PGG shape the dynamics of growing populations. \ua9 2019, The Author(s)
Non-abelian magnetic black strings versus black holes
We present dimensional pure magnetic Yang-Mills (YM) black strings (or
branes) induced by the dimensional Einstein-Yang-Mills-Dilaton black
holes. Born-Infeld version of the YM field makes our starting point which goes
to the standard YM field through a limiting procedure. The lifting from black
holes to black strings, (with less number of fields) is by adding an extra,
compact coordinate. This amounts to the change of horizon topology from
to a product structure. Our black string in dimensions is a
rather special one, with uniform Hawking temperature and non-asymptotically
flat structure. As the YM charge becomes large the string gets thinner to tend
into a breaking point and transform into a % dimensional black hole.Comment: 5 pages no figure; Final version to appear in EPJ
Spinal arthritis in invasive cane toads is linked to rate of dispersal as well as to latitude
Initial research on the spread of cane toads (Rhinella marina) through tropical Australia reported a high incidence of spinal arthritis (spondylosis) in toads at the invasion front (where toads disperse rapidly), but not in areas colonized earlier (where toads are more sedentary). The idea that spondylosis was a cost of rapid dispersal was challenged by wider spatial sampling which linked rates of spondylosis to hot (tropical) climates rather than to dispersal rates. Here, the authors of these competing interpretations collaborate to reinterpret the data. Our reanalysis supports both previous hypotheses; rates of spondylosis are higher in populations established by fast-dispersing toads, and are higher in tropical than in temperate environments; they are also higher in larger toads. The functional reason for climatic effects is unclear, but might involve effects on the soil-living bacteria involved in the induction of spondylosis; and/or may reflect higher movement (as opposed to dispersal) or more pronounced dry-season aggregation rates of toads in tropical conditions
High-accuracy comparison of numerical relativity simulations with post-Newtonian expansions
Numerical simulations of 15 orbits of an equal-mass binary black hole system
are presented. Gravitational waveforms from these simulations, covering more
than 30 cycles and ending about 1.5 cycles before merger, are compared with
those from quasi-circular zero-spin post-Newtonian (PN) formulae. The
cumulative phase uncertainty of these comparisons is about 0.05 radians,
dominated by effects arising from the small residual spins of the black holes
and the small residual orbital eccentricity in the simulations. Matching
numerical results to PN waveforms early in the run yields excellent agreement
(within 0.05 radians) over the first cycles, thus validating the
numerical simulation and establishing a regime where PN theory is accurate. In
the last 15 cycles to merger, however, {\em generic} time-domain Taylor
approximants build up phase differences of several radians. But, apparently by
coincidence, one specific post-Newtonian approximant, TaylorT4 at 3.5PN order,
agrees much better with the numerical simulations, with accumulated phase
differences of less than 0.05 radians over the 30-cycle waveform.
Gravitational-wave amplitude comparisons are also done between numerical
simulations and post-Newtonian, and the agreement depends on the post-Newtonian
order of the amplitude expansion: the amplitude difference is about 6--7% for
zeroth order and becomes smaller for increasing order. A newly derived 3.0PN
amplitude correction improves agreement significantly ( amplitude
difference throughout most of the run, increasing to 4% near merger) over the
previously known 2.5PN amplitude terms.Comment: Updated to agree with published version (various minor
clarifications; added description of AH finder in Sec IIB; added discussion
of tidal heating in Sec VC
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