6,935 research outputs found
Prospects For Identifying Dark Matter With CoGeNT
It has previously been shown that the excess of events reported by the CoGeNT
collaboration could be generated by elastically scattering dark matter
particles with a mass of approximately 5-15 GeV. This mass range is very
similar to that required to generate the annual modulation observed by
DAMA/LIBRA and the gamma rays from the region surrounding the Galactic Center
identified within the data of the Fermi Gamma Ray Space Telescope. To
confidently conclude that CoGeNT's excess is the result of dark matter,
however, further data will likely be needed. In this paper, we make projections
for the first full year of CoGeNT data, and for its planned upgrade. Not only
will this body of data more accurately constrain the spectrum of nuclear recoil
events, and corresponding dark matter parameter space, but will also make it
possible to identify seasonal variations in the rate. In particular, if the
CoGeNT excess is the product of dark matter, then one year of CoGeNT data will
likely reveal an annual modulation with a significance of 2-3. The
planned CoGeNT upgrade will not only detect such an annual modulation with high
significance, but will be capable of measuring the energy spectrum of the
modulation amplitude. These measurements will be essential to irrefutably
confirming a dark matter origin of these events.Comment: 6 pages, 6 figure
Fundamental Properties of the Highly Ionized Plasmas in the Milky Way
The cooling transition temperature gas in the interstellar medium (ISM),
traced by the high ions, Si IV, C IV, N V, and O VI, helps to constrain the
flow of energy from the hot ISM with T >10^6 K to the warm ISM with T< 2x10^4
K. We investigate the properties of this gas along the lines of sight to 38
stars in the Milky Way disk using 1.5-2.7 km/s resolution spectra of Si IV, C
IV, and N V absorption from the Space Telescope Imaging Spectrograph (STIS),
and 15 km/s resolution spectra of O VI absorption from the Far Ultraviolet
Spectroscopic Explorer (FUSE). The absorption by Si IV and C IV exhibits broad
and narrow components while only broad components are seen in N V and O VI. The
narrow components imply gas with T<7x10^4 K and trace two distinct types of
gas. The strong, saturated, and narrow Si IV and C IV components trace the gas
associated with the vicinities of O-type stars and their supershells. The
weaker narrow Si IV and C IV components trace gas in the general ISM that is
photoionized by the EUV radiation from cooling hot gas or has radiatively
cooled in a non-equilibrium manner from the transition temperature phase, but
rarely the warm ionized medium (WIM) probed by Al III. The broad Si IV, C IV, N
V, and O VI components trace collisionally ionized gas that is very likely
undergoing a cooling transition from the hot ISM to the warm ISM. The cooling
process possibly provides the regulation mechanism that produces N(C IV)/N(Si
IV) = 3.9 +/- 1.9. The cooling process also produces absorption lines where the
median and mean values of the line widths increase with the energy required to
create the ion.Comment: Accepted for publication in the ApJ. Only this PDF file contains all
the figures and tables in a single fil
Federal Prosecution of State and Local Public Officials: The Obstacles to Punishing Breaches of the Public Trust and a Proposal for Reform, Part Two
Vertex operators and the geometry of moduli spaces of framed torsion-free sheaves
We define complexes of vector bundles on products of moduli spaces of framed
rank r torsion-free sheaves on the complex projective plane. The top
non-vanishing Chern classes of the cohomology of these complexes yield actions
of the r-colored Heisenberg and Clifford algebras on the equivariant cohomology
of the moduli spaces. In this way we obtain a geometric realization of the
boson-fermion correspondence and related vertex operators.Comment: 36 pages; v2: Definition of geometric Heisenberg operators modified;
v3: Minor typos correcte
Quantum-field dynamics of expanding and contracting Bose-Einstein condensates
We analyze the dynamics of quantum statistics in a harmonically trapped
Bose-Einstein condensate, whose two-body interaction strength is controlled via
a Feshbach resonance. From an initially non-interacting coherent state, the
quantum field undergoes Kerr squeezing, which can be qualitatively described
with a single mode model. To render the effect experimentally accessible, we
propose a homodyne scheme, based on two hyperfine components, which converts
the quadrature squeezing into number squeezing. The scheme is numerically
demonstrated using a two-component Hartree-Fock-Bogoliubov formalism.Comment: 9 pages, 4 figure
Quantum measurement and decoherence
Distribution functions defined in accord with the quantum theory of
measurement are combined with results obtained from the quantum Langevin
equation to discuss decoherence in quantum Brownian motion. Closed form
expressions for wave packet spreading and the attenuation of coherence of a
pair of wave packets are obtained. The results are exact within the context of
linear passive dissipation. It is shown that, contrary to widely accepted
current belief, decoherence can occur at high temperature in the absence of
dissipation. Expressions for the decoherence time with and without dissipation
are obtained that differ from those appearing in earlier discussions
Quartet S Wave Neutron Deuteron Scattering in Effective Field Theory
The real and imaginary part of the quartet S wave phase shift in nd
scattering (^4 S_{3/2}) for centre-of-mass momenta of up to 300 MeV (E_cm
\approx 70 MeV) is presented in effective field theory, using both perturbative
pions and a theory in which pions are integrated out. As available, the
calculation agrees with both experimental data and potential model
calculations, but extends to a higher, so far untested momentum r\'egime above
the deuteron breakup point. A Lagrangean more feasible for numerical
computations is derived.Comment: 27 pages LaTeX2e with 11 figures, uses packages includegraphicx (6
.eps files), color and feynmp (necessary Metapost files included).
Corrections in bibliography and NNLO results added above breaku
Abortion provision in Northern Ireland: the views of health professionals working in obstetrics and gynaecology units
Introduction: Abortion became decriminalised in Northern Ireland in October 2019. Until that point there existed no evidence concerning the views of health professionals on decriminalisation or on their willingness to be involved in abortion care. The purpose of this study was to address this lack of evidence, including all categories of health professionals working in obstetrics and gynaecology units in Northern Ireland.
Methods: The online survey was targeted at medical, nursing and midwifery staff working in the obstetrics and gynaecology units in each Health and Social Care (HSC) Trust in Northern Ireland. The survey was issued via clinical directors in each Trust using the REDCap platform.
Results: The findings showed widespread support for decriminalisation of abortion up until 24 weeks’ gestation (n=169, 54%). The majority of clinicians stated they were willing to provide abortions in certain circumstances (which were undefined) (n=188, 60% medical abortions; n=157, 50% surgical abortions). Despite regional variation, the results show that there are sufficient numbers of clinicians to provide a service within each HSC Trust. The results indicate that many clinicians who report a religious affiliation are also supportive of decriminalisation (n=46, 51% Catholic; n=53, 45% Protestant) and are willing to provide care, countering the assumption that those of faith would all raise conscientious objections to service provision.
Conclusions: The findings of this study are very encouraging for the development, implementation and delivery of local abortion care within HSC Trusts in Northern Ireland and should be of value in informing commissioners and providers about the design of a service model and its underpinning training programmes
Discovery of the first tau Sco analogues: HD 66665 and HD 63425
The B0.2 V magnetic star tau Sco stands out from the larger population of
massive OB stars due to its high X-ray activity, peculiar wind diagnostics and
highly complex magnetic field. This paper presents the discovery of the first
two tau Sco analogues - HD 66665 and HD 63425, identified by the striking
similarity of their UV spectra to that of tau Sco. ESPaDOnS spectropolarimetric
observations were secured by the Magnetism in Massive Stars CFHT Large Program,
in order to characterize the stellar and magnetic properties of these stars.
CMFGEN modelling of optical ESPaDOnS spectra and archived IUE UV spectra showed
that these stars have stellar parameters similar to those of tau Sco. A
magnetic field of similar surface strength is found on both stars, reinforcing
the connection between the presence of a magnetic field and wind peculiarities.
However, additional phase-resolved observations will be required in order to
assess the potential complexity of the magnetic fields, and verify if the wind
anomalies are linked to this property.Comment: 6 pages, 2 tables, 3 figures. Accepted for publication in MNRAS. The
definitive version will be available at www.blackwel-synergy.co
Understanding the dynamics of segregation bands of simulated granular material in a rotating drum
Axial segregation of a binary mixture of grains in a rotating drum is studied
using Molecular Dynamics (MD) simulations. A force scheme leading to a constant
restitution coefficient is used and shows that axial segregation is possible
between two species of grains made of identical material differing by size.
Oscillatory motion of bands is investigated and the influence of the frictional
properties elucidated. The mechanism of bands merging is explained using direct
imaging of individual grains
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