15,618 research outputs found
A general numerical analysis program for the superconducting quasiparticle mixer
A user-oriented computer program SISCAP (SIS Computer Analysis Program) for analyzing SIS mixers is described. The program allows arbitrary impedance terminations to be specified at all LO harmonics and sideband frequencies. It is therefore able to treat a much more general class of SIS mixers than the widely used three-frequency analysis, for which the harmonics are assumed to be short-circuited. An additional program, GETCHI, provides the necessary input data to program SISCAP. The SISCAP program performs a nonlinear analysis to determine the SIS junction voltage waveform produced by the local oscillator. The quantum theory of mixing is used in its most general form, treating the large signal properties of the mixer in the time domain. A small signal linear analysis is then used to find the conversion loss and port impedances. The noise analysis includes thermal noise from the termination resistances and shot noise from the periodic LO current. Quantum noise is not considered. Many aspects of the program have been adequately verified and found accurate
The Architecture of MEG Simulation and Analysis Software
MEG (Mu to Electron Gamma) is an experiment dedicated to search for the
decay that is strongly suppressed in the Standard
Model but predicted in several Super Symmetric extensions of it at an
accessible rate. MEG is a small-size experiment ( physicists at
any time) with a life span of about 10 years. The limited human resource
available, in particular in the core offline group, emphasized the importance
of reusing software and exploiting existing expertise. Great care has been
devoted to provide a simple system that hides implementation details to the
average programmer. That allowed many members of the collaboration to
contribute to the development of the software of the experiment with limited
programming skill. The offline software is based on two frameworks: {\bf REM}
in FORTRAN 77 used for the event generation and detector simulation package
{\bf GEM}, based on GEANT 3, and {\bf ROME} in C++ used in the readout
simulation {\bf Bartender} and in the reconstruction and analysis program {\bf
Analyzer}. Event display in the simulation is based on GEANT 3 graphic
libraries and in the reconstruction on ROOT graphic libraries. Data are stored
in different formats in various stage of the processing. The frameworks include
utilities for input/output, database handling and format conversion transparent
to the user.Comment: Presented at the IEEE NSS Knoxville, 2010 Revised according to
referee's remarks Accepted by European Physical Journal Plu
Conserving and gapless approximations for the composite bosons in terms of the constituent fermions
A long-standing problem with the many-body approximations for interacting
condensed bosons has been the dichotomy between the ``conserving'' and
``gapless'' approximations, which either obey the conservations laws or satisfy
the Hugenholtz-Pines condition for a gapless excitation spectrum, in the order.
It is here shown that such a dichotomy does not exist for a system of composite
bosons, which form as bound-fermion pairs in the strong-coupling limit of the
fermionic attraction. By starting from the constituent fermions, for which
conserving approximations can be constructed for any value of the mutual
attraction according to the Baym-Kadanoff prescriptions, it is shown that these
approximations also result in a gapless excitation spectrum for the boson-like
propagators in the broken-symmetry phase. This holds provided the corresponding
equations for the fermionic single- and two-particle Green's functions are
solved self-consistently.Comment: 4 pages, 1 figur
A Rigorous Proof of Fermi Liquid Behavior for Jellium Two-Dimensional Interacting Fermions
Using the method of continuous constructive renormalization group around the
Fermi surface, it is proved that a jellium two-dimensional interacting system
of Fermions at low temperature remains analytic in the coupling constant
for where is some numerical constant
and is the temperature. Furthermore in that range of parameters, the first
and second derivatives of the self-energy remain bounded, a behavior which is
that of Fermi liquids and in particular excludes Luttinger liquid behavior. Our
results prove also that in dimension two any transition temperature must be
non-perturbative in the coupling constant, a result expected on physical
grounds. The proof exploits the specific momentum conservation rules in two
dimensions.Comment: 4 pages, no figure
Charged-Current Disappearance Measurements in the NuMI Off-Axis Beam
This article studies the potential of combining charged-current disappearance
measurements of \nu_{\mu} to \nu_{\tau} from MINOS and an off-axis beam. I find
that the error on \Delta m^2 from a 100 kt-yr off-axis measurement is a few
percent of itself. Further, I find little improvement to an off-axis
measurement by combining it with MINOS.Comment: Presented at NuFact'02. Four pages, three figure
KMS, etc
A general form of the ``Wick rotation'', starting from imaginary-time Green
functions of quantum-mechanical systems in thermal equilibrium at positive
temperature, is established. Extending work of H. Araki, the role of the KMS
condition and of an associated anti-unitary symmetry operation, the ``modular
conjugation'', in constructing analytic continuations of Green functions from
real- to imaginary times, and back, is clarified.
The relationship between the KMS condition for the vacuum with respect to
Lorentz boosts, on one hand, and the spin-statistics connection and the PCT
theorem, on the other hand, in local, relativistic quantum field theory is
recalled.
General results on the reconstruction of local quantum theories in various
non-trivial gravitational backgrounds from ``Euclidian amplitudes'' are
presented. In particular, a general form of the KMS condition is proposed and
applied, e.g., to the Unruh- and the Hawking effects.
This paper is dedicated to Huzihiro Araki on the occasion of his seventieth
birthday, with admiration, affection and best wishes.Comment: 56 pages, submitted to J. Math. Phy
Monitoring neurotoxins in industry: development of a neurobehavioral test battery
Huguet Françoise. 104 - Elémens (Les) ou premières instructions de la jeunesse. In: , . Les Livres pour l'Enfance et la Jeunesse de Gutenberg à Guizot. Les collections de la Bibliothèque de l'Institut National de Recherche Pédagogique. Paris : Institut national de recherche pédagogique, 1997. p. 57. (Bibliothèque de l'Histoire de l'Education, 16
Role of the neurologist in hazard identification and risk assessment.
This review describes strategies used by a clinical neurologist in the investigation of neurotoxic disease. It emphasizes the need for a high level of suspicion that environmental substances are capable of producing impairments in neurologic and neurobehavioral functions. Because of the difficulties in differentiating neurotoxic from nonneurotoxic disease when presented with common neurological symptoms, it is necessary to rely upon corroborative evidence from past medical records, work and environmental histories, and exposure data, as well as detailed neurological examinations, to reach a conclusion about causation. Sensitive electrophysiologic and neuropsychologic test batteries are useful in identifying subclinical impairments and in providing objective confirmation of abnormalities in the central and peripheral nervous systems. Combining scientific and epidemiologic information with experience and clinical judgment, these sources of information are used in the formulation of a clinical diagnosis. When many patients among a group of people are exposed to neurotoxicants, the effects of the exposure may vary from one to another because of differences in susceptibility, duration of exposure and dosage of neurotoxicant, and other possible risk factors. Group statistics may obscure a significant effect for the larger group, despite clinically obvious effects in an individual. The neurologist applies clinical skills and refers to the accumulated neurotoxicologic literature as a frame of reference to make a diagnosis about an individual patient or a group of patients who have been exposed to particular neurotoxicants. The Boston University Environmental Neurology Assessment (BUENA) is a scheme that attempts to combine epidemiologic methodology and clinical approaches to detect effects of neurotoxic exposure. The advantages and limitations of such a strategy are discussed
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