9,754 research outputs found
Complementarity relation for irreversible process derived from stochastic energetics
When the process of a system in contact with a heat bath is described by
classical Langevin equation, the method of stochastic energetics [K. Sekimoto,
J. Phys. Soc. Jpn. vol. 66 (1997) p.1234] enables to derive the form of
Helmholtz free energy and the dissipation function of the system. We prove that
the irreversible heat Q_irr and the time lapse $Delta t} of an isothermal
process obey the complementarity relation, Q_irr {Delta t} >= k_B T S_min,
where S_min depends on the initial and the final values of the control
parameters, but it does not depend on the pathway between these values.Comment: 3 pages. LaTeX with 6 style macro
ARIA 2016 : Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle
European Innovation Partnership on Active and Healthy Ageing Reference Site MACVIA-France, EU Structural and Development Fund Languedoc-Roussillon, ARIA.Peer reviewedPublisher PD
Six solutions for more reliable infant research
Infant research is often underpowered, undermining the robustness and replicability of our findings. Improving the reliability of infant studies offers a solution for increasing statistical power independent of sample size. Here, we discuss two senses of the term reliability in the context of infant research: reliable (large) effects and reliable measures. We examine the circumstances under which effects are strongest and measures are most reliable and use synthetic datasets to illustrate the relationship between effect size, measurement reliability, and statistical power. We then present six concrete solutions for more reliable infant research: (a) routinely estimating and reporting the effect size and measurement reliability of infant tasks, (b) selecting the best measurement tool, (c) developing better infant paradigms, (d) collecting more data points per infant, (e) excluding unreliable data from the analysis, and (f) conducting more sophisticated data analyses. Deeper consideration of measurement in infant research will improve our ability to study infant development
Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the hot Jupiter WASP-4b
We present the complete optical transmission spectrum of the hot Jupiter
WASP-4b from 440-940 nm at R ~ 400-1500 obtained with the Gemini Multi-Object
Spectrometers (GMOS); this is the first result from a comparative
exoplanetology survey program of close-in gas giants conducted with GMOS.
WASP-4b has an equilibrium temperature of 1700 K and is favorable to study in
transmission due to a large scale height (370 km). We derive the transmission
spectrum of WASP-4b using 4 transits observed with the MOS technique. We
demonstrate repeatable results across multiple epochs with GMOS, and derive a
combined transmission spectrum at a precision about twice above photon noise,
which is roughly equal to to one atmospheric scale height. The transmission
spectrum is well fitted with a uniform opacity as a function of wavelength. The
uniform opacity and absence of a Rayleigh slope from molecular hydrogen suggest
that the atmosphere is dominated by clouds with condensate grain size of ~1 um.
This result is consistent with previous observations of hot Jupiters since
clouds have been seen in planets with similar equilibrium temperatures to
WASP-4b. We describe a custom pipeline that we have written to reduce GMOS
time-series data of exoplanet transits, and present a thorough analysis of the
dominant noise sources in GMOS, which primarily consist of wavelength- and
time- dependent displacements of the spectra on the detector, mainly due to a
lack of atmospheric dispersion correction.Comment: 23 pages, 12 figures, accepted for publication in AJ, 2017 July
General relativity histories theory II: Invariance groups
We show in detail how the histories description of general relativity carries
representations of both the spacetime diffeomorphisms group and the Dirac
algebra of constraints. We show that the introduction of metric-dependent
equivariant foliations leads to the crucial result that the canonical
constraints are invariant under the action of spacetime diffeomorphisms.
Furthermore, there exists a representation of the group of generalised
spacetime mappings that are functionals of the four-metric: this is a spacetime
analogue of the group originally defined by Bergmann and Komar in the context
of the canonical formulation of general relativity. Finally, we discuss the
possible directions for the quantization of gravity in histories theory.Comment: 24 pages, submitted to Class. Quant. Gra
Fluctuation superconductivity limited noise in a transition-edge sensor
In order to investigate the origin of the until now unaccounted excess noise
and to minimize the uncontrollable phenomena at the transition in X-ray
microcalorimeters we have developed superconducting transition-edge sensors
into an edgeless geometry, the so-called Corbino disk (CorTES), with
superconducting contacts in the centre and at the outer perimeter. The measured
rms current noise and its spectral density can be modeled as resistance noise
resulting from fluctuations near the equilibrium superconductor-normal metal
boundaryComment: 9 pages, 4 figures.; Corrections to text and equations; replaced the
affected figures. Added reference [12
Planetary and Light Motions From Newtoinian Theory: An Amusing Exercise
We attempt to see how closely we can formally obtain the planetary and light
path equations of General Relativity by employing certain operations on the
familiar Newtonian equation. This article is intended neither as an alternative
to nor as a tool for grasping Einstein's General Relativity. Though the
exercise is understandable by readers at large, it is especially recommended to
the teachers of Relativity for an appreciative understanding of its peculiarity
as well as its pedagogical value in the teaching of differential equations.Comment: 7 page
Lepton number violating interactions and their effects on neutrino oscillation experiments
Mixing between bosons that transform differently under the standard model
gauge group, but identically under its unbroken subgroup, can induce
interactions that violate the total lepton number. We discuss four-fermion
operators that mediate lepton number violating neutrino interactions both in a
model-independent framework and within supersymmetry (SUSY) without R-parity.
The effective couplings of such operators are constrained by: i) the upper
bounds on the relevant elementary couplings between the bosons and the
fermions, ii) by the limit on universality violation in pion decays, iii) by
the data on neutrinoless double beta decay and, iv) by loop-induced neutrino
masses. We find that the present bounds imply that lepton number violating
neutrino interactions are not relevant for the solar and atmospheric neutrino
problems. Within SUSY without R-parity also the LSND anomaly cannot be
explained by such interactions, but one cannot rule out an effect
model-independently. Possible consequences for future terrestrial neutrino
oscillation experiments and for neutrinos from a supernova are discussed.Comment: 28 pages, 2 figures, Late
Gauge transformations in the Lagrangian and Hamiltonian formalisms of generally covariant theories
We study spacetime diffeomorphisms in Hamiltonian and Lagrangian formalisms
of generally covariant systems. We show that the gauge group for such a system
is characterized by having generators which are projectable under the Legendre
map. The gauge group is found to be much larger than the original group of
spacetime diffeomorphisms, since its generators must depend on the lapse
function and shift vector of the spacetime metric in a given coordinate patch.
Our results are generalizations of earlier results by Salisbury and
Sundermeyer. They arise in a natural way from using the requirement of
equivalence between Lagrangian and Hamiltonian formulations of the system, and
they are new in that the symmetries are realized on the full set of phase space
variables. The generators are displayed explicitly and are applied to the
relativistic string and to general relativity.Comment: 12 pages, no figures; REVTeX; uses multicol,fancyheadings,eqsecnum;
to appear in Phys. Rev.
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