12,946 research outputs found
Hawking Radiation as Tunneling
We present a short and direct derivation of Hawking radiation as a tunneling
process, based on particles in a dynamical geometry. The imaginary part of the
action for the classically forbidden process is related to the Boltzmann factor
for emission at the Hawking temperature. Because the derivation respects
conservation laws, the exact spectrum is not precisely thermal. We compare and
contrast the problem of spontaneous emission of charged particles from a
charged conductor.Comment: LaTeX, 10 pages; v2. journal version, added section on relation of
black hole radiation to electric charge emission from a charged conducting
sphere; v3. restored cut referenc
Flexible control techniques for a lunar base
The fundamental elements found in every terrestrial control system can be employed in all lunar applications. These elements include sensors which measure physical properties, controllers which acquire sensor data and calculate a control response, and actuators which apply the control output to the process. The unique characteristics of the lunar environment will certainly require the development of new control system technology. However, weightlessness, harsh atmospheric conditions, temperature extremes, and radiation hazards will most significantly impact the design of sensors and actuators. The controller and associated control algorithms, which are the most complex element of any control system, can be derived in their entirety from existing technology. Lunar process control applications -- ranging from small-scale research projects to full-scale processing plants -- will benefit greatly from the controller advances being developed today. In particular, new software technology aimed at commercial process monitoring and control applications will almost completely eliminate the need for custom programs and the lengthy development and testing cycle they require. The applicability of existing industrial software to lunar applications has other significant advantages in addition to cost and quality. This software is designed to run on standard hardware platforms and takes advantage of existing LAN and telecommunications technology. Further, in order to exploit the existing commercial market, the software is being designed to be implemented by users of all skill levels -- typically users who are familiar with their process, but not necessarily with software or control theory. This means that specialized technical support personnel will not need to be on-hand, and the associated costs are eliminated. Finally, the latest industrial software designed for the commercial market is extremely flexible, in order to fit the requirements of many types of processing applications with little or no customization. This means that lunar process control projects will not be delayed by unforeseen problems or last minute process modifications. The software will include all of the tools needed to adapt to virtually any changes. In contrast to other space programs which required the development of tremendous amounts of custom software, lunar-based processing facilities will benefit from the use of existing software technology which is being proven in commercial applications on Earth
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Sartorial symbols of social class elicit class-consistent behavioral and physiological responses: a dyadic approach.
Social rank in human and nonhuman animals is signaled by a variety of behaviors and phenotypes. In this research, we examined whether a sartorial manipulation of social class would engender class-consistent behavior and physiology during dyadic interactions. Male participants donned clothing that signaled either upper-class (business-suit) or lower-class (sweatpants) rank prior to engaging in a modified negotiation task with another participant unaware of the clothing manipulation. Wearing upper-class, compared to lower-class, clothing induced dominance--measured in terms of negotiation profits and concessions, and testosterone levels--in participants. Upper-class clothing also elicited increased vigilance in perceivers of these symbols: Relative to perceiving lower-class symbols, perceiving upper-class symbols increased vagal withdrawal, reduced perceptions of social power, and catalyzed physiological contagion such that perceivers' sympathetic nervous system activation followed that of the upper-class target. Discussion focuses on the dyadic process of social class signaling within social interactions
Renormalization of supersymmetric Yang-Mills theories with soft supersymmetry breaking
The renormalization of supersymmetric Yang-Mills theories with soft
supersymmetry breaking is presented using spurion fields for introducing the
breaking terms. It is proven that renormalization of the fields and parameters
in the classical action yields precisely the correct counterterms to cancel all
divergences. In the course of the construction of higher orders additional
independent parameters appear, but they can be shown to be irrelevant in
physics respects. Thus, the only parameters with influence on physical
amplitudes are the supersymmetric and the well-known soft breaking parameters.Comment: 29 pages, published in The European Physical Journal
Improved quantum metrology using quantum error-correction
We consider quantum metrology in noisy environments, where the effect of
noise and decoherence limits the achievable gain in precision by quantum
entanglement. We show that by using tools from quantum error-correction this
limitation can be overcome. This is demonstrated in two scenarios, including a
many-body Hamiltonian with single-qubit dephasing or depolarizing noise, and a
single-body Hamiltonian with transversal noise. In both cases we show that
Heisenberg scaling, and hence a quadratic improvement over the classical case,
can be retained. Moreover, for the case of frequency estimation we find that
the inclusion of error-correction allows, in certain instances, for a finite
optimal interrogation time even in the asymptotic limit.Comment: Version 2 is the published version. Appendices contain Supplemental
materia
Information-disturbance tradeoff in quantum measurements
We present a simple information-disturbance tradeoff relation valid for any
general measurement apparatus: The disturbance between input and output states
is lower bounded by the information the apparatus provides in distinguishing
these two states.Comment: 4 Pages, 1 Figure. Published version (reference added and minor
changes performed
Perceptions of Blame in Intimate Partner Violence: The Role of the Perpetrator\u27s Ability to Arouse Fear of Injury in the Victim
Men are more likely to be blamed more for intimate partner violence (IPV) than are women who commit the same offense. However, because men are typically stronger and perceived as more physically aggressive than women are, perpetrator sex is confounded with masculinity and the ability to arouse fear in the victim. This study disentangled the construct of gender in understanding bystanders’ attributions of blame in IPV. Participants (N = 639) read a scenario in which the perpetrator’s sex (male/female) and gender identity (masculine/feminine), and the victim’s sex (male/female) were manipulated and rated how much they blamed the perpetrator and the perpetrator’s ability to arouse fear of injury in the victim. Results showed that male perpetrators (regardless of gender identity) who assaulted a female victim were attributed the most blame and were perceived as having the greatest ability to arouse victim fear. In contrast, feminine female perpetrators were attributed the least blame and perceived as arousing the least victim fear regardless of the victim’s gender. Furthermore, controlling for the perpetrator’s ability to arouse fear in the victim resulted in the elimination of the interaction effects for blame. This finding suggests that perpetrators’ ability to arouse fear is an underlying factor in bystanders’ attributions of blame
Testing the Metal of Late-Type Kepler Planet Hosts with Iron-Clad Methods
It has been shown that F, G, and early K dwarf hosts of Neptune-sized planets
are not preferentially metal-rich. However, it is less clear whether the same
holds for late K and M dwarf planet hosts. We report metallicities of Kepler
targets and candidate transiting planet hosts with effective temperatures below
4500 K. We use new metallicity calibrations to determine [Fe/H] from visible
and near-infrared spectra. We find that the metallicity distribution of late K
and M dwarfs monitored by Kepler is consistent with that of the solar
neighborhood. Further, we show that hosts of Earth- to Neptune-sized planets
have metallicities consistent with those lacking detected planets and rule out
a previously claimed 0.2 dex offset between the two distributions at 6sigma
confidence. We also demonstrate that the metallicities of late K and M dwarfs
hosting multiple detected planets are consistent with those lacking detected
planets. Our results indicate that multiple terrestrial and Neptune-sized
planets can form around late K and M dwarfs with metallicities as low as 0.25
of the solar value. The presence of Neptune-sized planets orbiting such
low-metallicity M dwarfs suggests that accreting planets collect most or all of
the solids from the disk and that the potential cores of giant planets can
readily form around M dwarfs. The paucity of giant planets around M dwarfs
compared to solar-type stars must be due to relatively rapid disk evaporation
or a slower rate of core accretion, rather than insufficient solids to form a
core.Comment: 9 pages, 5 figures. Accepted to Ap
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