580 research outputs found
Cranked Relativistic Hartree-Bogoliubov Theory: Superdeformed Bands in the Region
Cranked Relativistic Hartree-Bogoliubov (CRHB) theory is presented as an
extension of Relativistic Mean Field theory with pairing correlations to the
rotating frame. Pairing correlations are taken into account by a finite range
two-body force of Gogny type and approximate particle number projection is
performed by Lipkin-Nogami method. This theory is applied to the description of
yrast superdeformed rotational bands observed in even-even nuclei of the mass region. Using the well established parameter sets NL1 for the
Lagrangian and D1S for the pairing force one obtains a very successful
description of data such as kinematic () and dynamic ()
moments of inertia without any adjustment of new parameters. Within the present
experimental accuracy the calculated transition quadrupole moments agree
reasonably well with the observed data.Comment: 6 pages including 4 PostScript figures, uses RevTex, revised version,
Phys.Rev. C, Rapid Communications, in pres
Carrier-mediated ferromagnetic ordering in Mn ion-implanted p+GaAs:C
Highly p-type GaAs:C was ion-implanted with Mn at differing doses to produce
Mn concentrations in the 1 - 5 at.% range. In comparison to LT-GaAs and
n+GaAs:Si samples implanted under the same conditions, transport and magnetic
properties show marked differences. Transport measurements show anomalies,
consistent with observed magnetic properties and with epi- LT-(Ga,Mn)As, as
well as the extraordinary Hall Effect up to the observed magnetic ordering
temperature (T_C). Mn ion-implanted p+GaAs:C with as-grown carrier
concentrations > 10^20 cm^-3 show remanent magnetization up to 280 K
Scanning tunneling microscopy at multiple voltage biases of stable "ring-like" Ag clusters on Si(111)-(77)
Since more than twenty years it is known that deposition of Ag onto
Si(111)-(7\times7) leads under certain conditions to the formation of so-called
"ring-like" clusters, that are particularly stable among small clusters. In
order to resolve their still unknown atomic structure, we performed voltage
dependent scanning tunneling microscopy (STM) measurements providing
interesting information about the electronic properties of clusters which are
linked with their atomic structure. Based on a structural model of Au cluster
on Si(111)-(7\times7) and our STM images, we propose an atomic arrangement for
the two most stable Ag "ring-like" clusters.Comment: 9 pages and 5 figure
A canonical correlation analysis of the association between carcass and ham traits in pigs used to produce dry-cured ham
The association between carcass and ham traits in a pig population used to produce dry-cured ham was studied using canonical correlation analysis. The carcass traits examined were hot carcass weight (HCW), backfat thickness (BT) and loin depth (LD), and the ham traits studied were gross ham weight (GHW), trimmed ham weight (THW), ham inner layer fat thickness (HIFT), ham outer layer fat thickness (HOFT), pH (pH) and the Göfo value. Carcass and ham traits are not independent. The canonical correlations (r) between the carcass and ham traits at 130 kg were 0.77, 0.24 and 0.20 for the first, second and third canonical pair, respectively, and were all significant (p < 0.01) by the Wilks test. The corresponding canonical correlations between the three canonical variate pairs for the carcass and ham traits at 160 kg were 0.88, 0.42 and 0.14, respectively (p < 0.05 for all, except the third). The correlations between the traits and their canonical variate showed an association among HCW, GHW and THW, and between BT and HOFT. These results indicate that carcass traits should be used to cull pigs that are not suitable for dry-cured ham production
Interstellar MHD Turbulence and Star Formation
This chapter reviews the nature of turbulence in the Galactic interstellar
medium (ISM) and its connections to the star formation (SF) process. The ISM is
turbulent, magnetized, self-gravitating, and is subject to heating and cooling
processes that control its thermodynamic behavior. The turbulence in the warm
and hot ionized components of the ISM appears to be trans- or subsonic, and
thus to behave nearly incompressibly. However, the neutral warm and cold
components are highly compressible, as a consequence of both thermal
instability in the atomic gas and of moderately-to-strongly supersonic motions
in the roughly isothermal cold atomic and molecular components. Within this
context, we discuss: i) the production and statistical distribution of
turbulent density fluctuations in both isothermal and polytropic media; ii) the
nature of the clumps produced by thermal instability, noting that, contrary to
classical ideas, they in general accrete mass from their environment; iii) the
density-magnetic field correlation (or lack thereof) in turbulent density
fluctuations, as a consequence of the superposition of the different wave modes
in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio
(MFR) in density fluctuations as they are built up by dynamic compressions; v)
the formation of cold, dense clouds aided by thermal instability; vi) the
expectation that star-forming molecular clouds are likely to be undergoing
global gravitational contraction, rather than being near equilibrium, and vii)
the regulation of the star formation rate (SFR) in such gravitationally
contracting clouds by stellar feedback which, rather than keeping the clouds
from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse
Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as
per referee's recommendation
The calibration system for the photomultiplier array of the SNO+ experiment
A light injection system using LEDs and optical fibres was designed for the calibration and monitoring of the photomultiplier array of the SNO+ experiment at SNOLAB. Large volume, non-segmented, low-background detectors for rare event physics, such as the multi-purpose SNO+ experiment, need a calibration system that allow an accurate and regular measurement of the performance parameters of their photomultiplier arrays, while minimising the risk of radioactivity ingress. The design implemented for SNO+ uses a set of optical fibres to inject light pulses from external LEDs into the detector. The design, fabrication and installation of this light injection system, as well as the first commissioning tests, are described in this paper. Monte Carlo simulations were compared with the commissioning test results, confirming that the system meets the performance requirements
Lifetime measurements and dipole transition rates for superdeformed states in 190Hg
High-precision lifetime measurements have been performed in two of the superdeformed (SD) bands of 190Hg with the Doppler-shift attenuation method. Intrinsic quadrupole moments, Q0, were extracted for the yrast and first excited SD bands in this nucleus. Dipole transition rates have been established for the inter-band transitions which connect the first excited SD band to the yrast states in the second minimum. The results support the interpretation of the excited SD band as a band based on an octupole vibration
Pancreatic involvement in fatal human leptospirosis: clinical and histopathological features
Superdeformation and prolate-oblate competition in Tl nuclei
Spectroscopic studies of weakly populated proton i13/2 bands in superdeformed Tl nuclei (around mass 190) and in the normally deformed, very light 183Tl nucleus are discussed. Among the results presented, the first measurement of a superdeformed quadrupole moment in an odd-Z nucleus, 191Tl, is reported. The experiments were conducted with the Gammasphere array as "stand-alone" device and coupled with the Argonne Fragment Mass Analyzer
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