6,232 research outputs found
Fluctuations of the Unruh Temperature
Using the influence functional formalism, the problem of an accelerating
detector in the presence of a scalar field in its ground state is considered in
Minkowski space. As is known since the work of Unruh, to a quantum mechanical
detector following a definite, classical acceleration, the field appears to be
thermally excited. We relax the requirement of perfect classicality for the
trajectory and substitute it with one of {\it derived} classicality through the
criteria of decoherence. The ensuing fluctuations in temperature are then
related with the time and the amplitude of excitation in the detector's
internal degree of freedom.Comment: LATEX, 12 pages + 2 figures (available upon request) MIT-CTP 234
Hermiticity and the Cohomology Condition in Topological Yang-Mills Theory
The symmetries of the topological Yang-Mills theory are studied in the
Hamiltonian formalism and the generators of the twisted N=2 superPoincar\'e
algebra are explicitly constructed. Noting that the twisted Lorentz generators
do not generate the Lorentz symmetry of the theory, we relate the two by
extracting from the latter the twisted version of the internal SU(2) generator.
The hermiticity properties of the various generators are also considered
throughout, and the boost generators are found to be non-hermitian. We then
recover the BRST cohomology condition on physical states from representation
theory arguments.Comment: 19 pages, MIT-CTP 223
It’s Not Just the What but the How
White House Task Force to Protect Students From Sexual Assault looked to Prevention Innovations Research Center to evaluate efficacy of strategies for prevention and response to sexual violence on campus
Latitudinal Variation in Seasonal Activity and Mortality in Ratsnakes (Elaphe obsoleta)
The ecology of ectotherms should be particularly affected by latitude because so much of their biology is temperature dependent. Current latitudinal patterns should also be informative about how ectotherms will have to modify their behavior in response to climate change. We used data from a total of 175 adult black ratsnakes (Elaphe obsoleta) radio tracked in Ontario, Illinois, and Texas, a latitudinal distance of \u3e 1500 km, to test predictions about how seasonal patterns of activity and mortality should vary with latitude. Despite pronounced differences in temperatures among study locations, and despite ratsnakes in Texas not hibernating and switching from diurnal to nocturnal activity in the summer, seasonal patterns of snake activity were remarkably similar during the months that snakes in all populations were active. Rather than being a function of temperature, activity may be driven by the timing of reproduction, which appears similar among populations. Contrary to the prediction that mortality should be highest in the most active population, overall mortality did not follow a clinal pattern. Winter mortality did increase with latitude, however, consistent with temperature limiting the northern distribution of ratsnakes. This result was opposite that found in the only previous study of latitudinal variation in winter mortality in reptiles, which may be a consequence of whether or not the animals exhibit true hibernation. Collectively, these results suggest that, at least in the northern part of their range, ratsnakes should be able to adjust easily to, and may benefit from, a warmer climate, although climate-based changes to the snakes\u27 prey or habitat, for example, could alter that prediction
The elusive old population of the dwarf spheroidal galaxy Leo I
We report the discovery of a significant old population in the dwarf
spheroidal (dSph) galaxy Leo I as a result of a wide-area search with the ESO
New Technology Telescope. Studies of the stellar content of Local Group dwarf
galaxies have shown the presence of an old stellar population in almost all of
the dwarf spheroidals. The only exception was Leo I, which alone appeared to
have delayed its initial star formation episode until just a few Gyr ago. The
color-magnitude diagram of Leo I now reveals an extended horizontal branch,
unambiguously indicating the presence of an old, metal-poor population in the
outer regions of this galaxy. Yet we find little evidence for a stellar
population gradient, at least outside R > 2' (0.16 kpc), since the old
horizontal branch stars of Leo I are radially distributed as their more
numerous intermediate-age helium-burning counterparts. The discovery of a
definitely old population in the predominantly young dwarf spheroidal galaxy
Leo I points to a sharply defined first epoch of star formation common to all
of the Local Group dSph's as well as to the halo of the Milky Way.Comment: 4 pages, 3 postscript figures, uses apjfonts.sty, emulateapj.sty.
Accepted for publication in ApJ Letter
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The moral microfoundations of institutional complexity: Sustainability implementation as compromise-making at an oil sands company
Research on institutional complexity has overlooked the fact that moral judgements are likely involved when individuals face a plurality of logics within organizations. To analyze the moral microfoundations of institutional complexity, we build on Boltanski and Thévenot’s (2006 [1991]) economies of worth (EW) framework and explore how individuals produce moral judgement in response to the institutional complexity triggered by a major shift in the sustainability strategy within an oil sands company. Fifty-two interviews with employees, managers and executives reveal how actors rely on four types of justification that combine different moral principles and related objects with the aim of either forming (sheltering and solidifying work) or challenging (fragilizing and deconstructing work) a new compromise with regard to sustainability within the organization. Our results show how the EW framework can enrich institutional complexity theory by bringing morality back into the analysis as a core dimension of inhabited institutions while advancing the microanalysis of compromise-making around sustainability in organization studies
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
Magellanic Cloud Periphery Carbon Stars IV: The SMC
The kinematics of 150 carbon stars observed at moderate dispersion on the
periphery of the Small Magellanic Cloud are compared with the motions of
neutral hydrogen and early type stars in the Inter-Cloud region. The
distribution of radial velocities implies a configuration of these stars as a
sheet inclined at 73+/-4 degrees to the plane of the sky. The near side, to the
South, is dominated by a stellar component; to the North, the far side contains
fewer carbon stars, and is dominated by the neutral gas. The upper velocity
envelope of the stars is closely the same as that of the gas. This
configuration is shown to be consistent with the known extension of the SMC
along the line of sight, and is attributed to a tidally induced disruption of
the SMC that originated in a close encounter with the LMC some 0.3 to 0.4 Gyr
ago. The dearth of gas on the near side of the sheet is attributed to ablation
processes akin to those inferred by Weiner & Williams (1996) to collisional
excitation of the leading edges of Magellanic Stream clouds. Comparison with
pre LMC/SMC encounter kinematic data of Hardy, Suntzeff, & Azzopardi (1989) of
carbon stars, with data of stars formed after the encounter, of Maurice et al.
(1989), and Mathewson et al. (a986, 1988) leaves little doubt that forces other
than gravity play a role in the dynamics of the H I.Comment: 30 pages; 7 figures, latex compiled, 1 table; to appear in AJ (June
2000
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