6,920 research outputs found
On the one-loop correction of "phi^4" theory in higher dimensions
We have considered phi^4 theory in higher dimensions. Using functional
diagrammatic approach, we computed the one-loop correction to effective
potential of the scalar field in five dimensions. It is shown that phi^4 theory
can be regularised in five dimensions. Temperature dependent one-loop
correction and critical temperature T_c are computed and T_c depends on the
fundamental scale M of the theory. A brief discussion of symmetry restoration
is also presented. The nature of phase transitions is examined and is of second
orderComment: 8 pages, 5 figures. To appear in IJMP
A New Channel for the Detection of Planetary Systems Through Microlensing: II. Repeating Events
In the companion paper we began the task of systematically studying the
detection of planets in wide orbits () via microlensing surveys.
In this paper we continue, focusing on repeating events. We find that, if all
planetary systems are similar to our own Solar System, reasonable extensions of
the present observing strategies would allow us to detect 3-6 repeating events
per year along the direction to the Bulge. Indeed, if planetary systems with
multiple planets are common, then future monitoring programs which lead to the
discovery of thousands of stellar-lens events will likely discover events in
which several different planets within a single system serve as lenses, with
light curves exhibiting multiple repetitions. In this paper we discuss
observing strategies to maximize the discovery of all wide-orbit planet-lens
events. We also compare the likely detection rates of planets in wide orbits to
those of planets located in the zone for resonant lensing. We find that,
depending on the values of the planet masses and stellar radii of the lensed
sources (which determine whether or not finite source size is important), and
also on the sensitivity of the photometry used by observers, the detection of
planets in wide orbits may be the primary route to the discovery of planets via
microlensing. We also discuss how the combination of resonant and wide-orbit
events can help us to learn about the distribution of planetary system
properties (S 6.1). In addition, by determining the fraction of short-duration
events due to planets, we indirectly derive information about the fraction of
all short-duration events that may be due to low-mass MACHOs (S 6.2).Comment: 51 pages, 7 figures. To be published in the Astrophysical Journal, 20
February 1999. This completes the introduction to the discovery of planets in
wide orbits begun in astro-ph/9808075, also to appear in ApJ on 20 February
199
Dynamics of parametric fluctuations induced by quasiparticle tunneling in superconducting flux qubits
We present experiments on the dynamics of a two-state parametric fluctuator
in a superconducting flux qubit. In spectroscopic measurements, the fluctuator
manifests itself as a doublet line. When the qubit is excited in resonance with
one of the two doublet lines, the correlation of readout results exhibits an
exponential time decay which provides a measure of the fluctuator transition
rate. The rate increases with temperature in the interval 40 to 158 mK. Based
on the magnitude of the transition rate and the doublet line splitting we
conclude that the fluctuation is induced by quasiparticle tunneling. These
results demonstrate the importance of considering quasiparticles as a source of
decoherence in flux qubits.Comment: 12 pages, including supplementary informatio
A New Channel for the Detection of Planetary Systems Through Microlensing: I. Isolated Events Due to Planet Lenses
We propose and evaluate the feasibility of a new strategy to search for
planets via microlensing. This new strategy is designed to detect planets in
"wide" orbits, i.e., with orbital separation, greater than .
Planets in wide orbits may provide the dominant channel for the microlensing
discovery of planets, particularly low-mass (e.g., Earth-mass) planets. This
paper concentrates on events in which a single planet serves as a lens, leading
to an isolated event of short duration. We point out that a distribution of
events due to lensing by stars with wide-orbit planets is necessarily
accompanied by a distribution of shorter- duration events. The fraction of
events in the latter distribution is proportional to the average value of
, where is the ratio between \pl and stellar masses. The position
of the peak or peaks also provides a measure of the mass ratios typical of
planetary systems. We study detection strategies that can optimize our ability
to discover isolated short-duration events due to lensing by planets, and find
that monitoring employing sensitive photometry is particularly useful. If
planetary systems similar to our own are common, even modest changes in
detection strategy should lead to the discovery of a few isolated events of
short duration every year. We therefore also address the issue of the
contamination due to stellar populations of any microlensing signal due to
low-mass MACHOs. We describe how, even for isolated events of short duration,
it will be possible to test the hypothesis that the lens was a planet instead
of a low-mass MACHO, if the central star of the planetary system contributes a
measurable fraction of the baseline flux.Comment: 37 pages, 6 figure. To be published in the Astrophysical Journal.
This is part one of a series of papers on microlensing by planetary systems
containing wide-orbit planets; the series represents a reorganization and
extension of astro-ph/971101
Second Backbend in the Mass A ~ 180 Region
Within the framework of selfconsistent cranked Hartree-Fock- Bogoliubov
theory(one-dimensional) we predict second backbend in the yrast line of Os-182
at , which is even sharper than the first one observed
experimentally at .
Around such a high spin the structure becomes multi-quasiparticle type, but
the main source of this strong discontinuity is a sudden large alignment of
i_13/2 proton orbitals along the rotation axis followed soon by the alignment
of j_15/2 neutron orbitals. This leads to drastic structural changes at such
high spins. When experimentally confirmed, this will be observed for the first
time in this mass region, and will be at the highest spin so far.Comment: 13 pages, 4 ps figure
Optimal Microlensing Observations
One of the major limitations of microlensing observations toward the Large
Magellanic Cloud (LMC) is the low rate of event detection. What can be done to
improve this rate? Is it better to invest telescope time in more frequent
observations of the inner high surface-brightness fields, or in covering new,
less populated outer fields? How would a factor 2 improvement in CCD
sensitivity affect the detection efficiency? Would a series of major (factor
2--4) upgrades in telescope aperture, seeing, sky brightness, camera size, and
detector efficiency increase the event rate by a huge factor, or only
marginally? I develop a simplified framework to address these questions. With
observational resources fixed at the level of the MACHO and EROS experiments,
the biggest improvement (factor ~2) would come by reducing the time spent on
the inner ~25 deg^2 and applying it to the outer ~100 deg^2. By combining this
change with the characteristics of a good medium-size telescope (2.5 m mirror,
1" point spread function, thinned CCD chips, 1 deg^2 camera, and dark sky), it
should be possible to increase the detection of LMC events to more than 100 per
year (assuming current estimates of the optical depth apply to the entire LMC).Comment: Submitted to ApJ, 13 pages plus 3 figure
Management science and the development of human resource accounting
A common misconception about human resource accounting (HRA) is that it focuses narrowly upon financial accounting, that its purpose is to reflect the asset value of people on financial statements. The major purpose of HRA is to provide concepts and measurements to facilitate the effective and efficient management of human resources. It, therefore, represents a management accounting development
Trans-scaphoid dislocation of the proximal row: a case report
This report is of a 32 year old man who presented with complains of pain, swelling and deformity of right wrist of four weeks duration. He gave history of road traffic accident four weeks back leading to injury to right wrist; Preoperative radiographs and C.T. scan images were suggestive of trans-scaphoid dislocation of the proximal row of wrist. A volar and dorsal approach were used to reduce this complex dislocation but was not successful. Wrist arthodesis was performed after doing proximal row carpectomy. One year follow-up of the patient showed fair result with grip strength of 85% to contralateral side and modified Mayo wrist score of 65 at one year.Key words: Trans-scaphoid dislocation, CT scan, carpectomy, wrist scor
Nonclassical Light in Interferometric Measurements
It is shown that the even and odd coherent light and other nonclassical
states of light like superposition of coherent states with different phases may
replace the squeezed light in interferometric gravitational wave detector to
increase its sensitivity. (Contribution to the Second Workshop on Harmonic
Oscillator, Cocoyoc, Mexico, March 1994)Comment: 8 pages,LATEX,preprint of Naples University,
INFN-NA-IV-94/30,DSF-T-94/3
Quantum-limited time-frequency estimation through mode-selective photon measurement
By projecting onto complex optical mode profiles, it is possible to estimate
arbitrarily small separations between objects with quantum-limited precision,
free of uncertainty arising from overlapping intensity profiles. Here we extend
these techniques to the time-frequency domain using mode-selective
sum-frequency generation with shaped ultrafast pulses. We experimentally
resolve temporal and spectral separations between incoherent mixtures of
single-photon level signals ten times smaller than their optical bandwidths
with a ten-fold improvement in precision over the intensity-only Cram\'er-Rao
bound.Comment: Six pages, three figures. Comments welcome
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