2,843 research outputs found
Polarization of lepton from scalar tau decay as a probe of neutralino mixing
The lepton arising from the scalar tau (\st) decay is naturally
polarized. \ptau depends on the left--right mixing of the \st and the
gaugino--higgsino mixing of the neutralino. The polarization \ptau could be
measured from the energy distribution of the decay products of at future
\epem colliders. A measurement of \ptauand of the \st production cross
section allows to determine both these mixing angles.Comment: 20 pages Latex, 5 figures(not included). compressed ps file of the
figures available at ftp://ftp.kek.jp/kek/preprints/TH/TH-425/fig.ps.g
Exploring emergency physicians' professional identities: a Q-method study
Professional identities research in medical education has made significant contributions to the field. However, what comprises professional identities is rarely interrogated. This research tackles this relatively understudied component of professional identities research by understanding emergency medicine physicians’ perspectives on the important elements that comprise their professional identities. Q-methodology was used to identify different clusters of viewpoints on professional identities; by extension, the core components that comprise emergency medicine physicians’ professional identities are disclosed. Thirty-three emergency medicine physicians were recruited, through purposive sampling, from five hospitals across Taiwan. R software was used to analyse the Q-sorts, determine loadings on each viewpoint and formulate the viewpoint array. Analysis of interview data enhanced our understanding of these viewpoints. In total, twenty-five emergency medicine physicians loaded onto four distinct viewpoints, reflecting dominant perspectives of emergency medicine physicians’ understanding of their professional identities. These distinct viewpoints demonstrated what emergency medicine physicians deemed significant in how they understood themselves. The viewpoints comprised: skills acquisition, capabilities and practical wisdom; coping ability and resilience; professional recognition and self-esteem; and wellbeing and quality of life. All viewpoints stressed the importance of trust between colleagues. These findings demonstrate the multitude of ways in which seemingly unified professional identities diverge across groups of individuals. An enhanced understanding of speciality work culture is gained. By understanding facets of professional identities, the development of future educational interventions and departmental initiatives, which might support key components of professional identities, can be explored
P and T Odd Asymmetries in Lepton Flavor Violating Tau Decays
We calculated the differential cross sections of the processes in which one
of the pair created tau particles at an e^+ e^- collider decays into lepton
flavor violating final states e.g. tau -> mu gamma, tau -> 3 mu, tau -> mu ee.
Using the correlations between angular distributions of both sides of tau
decays, we can obtain information on parity and CP violations of lepton flavor
non-conserving interactions. The formulae derived here are useful in
distinguishing different models, since each model of physics beyond the
standard model predicts different angular correlations. We also calculate
angular distributions of the major background process to tau -> l gamma search,
namely tau -> l nu \bar{\nu} gamma, and discuss usefulness of the angular
correlation for background suppression.Comment: 31 pages, 5 figure
Are Great Disks Defined by Satellite Galaxies in Milky-Way Type Halos Rare in CDM model?
We study the spatial distribution of satellite galaxies by assuming that they
follow the dark matter distribution. This assumption is supported by
semi-analytical studies based on high-resolution numerical simulations. We find
that for a Milky-Way type halo, if only a dozen satellite galaxies are
observed, then they can lie on a ``great'' disk with an rms height of about 40
kpc. The normal to the plane is roughly isotropic on the sky. These results are
consistent with the observed properties of the satellite galaxies in the Milky
Way. If, however, the satellite galaxies follow the distribution of
substructure selected by present mass, then great disks similar to the one in
the Milky Way are rare and difficult to reproduce, in agreement with the
conclusion reached by Kroupa et al. (2004).Comment: Major revised, new figure and text added, to appear in A&
The dark matter halo of NGC 1399 - CDM or MOND?
Central galaxies in galaxy clusters may be key discriminants in the
competition between the cold dark matter (CDM) paradigm and modified Newtonian
dynamics (MOND). We investigate the dark halo of NGC 1399, the central galaxy
of the Fornax cluster, out to a galactocentric distance of 80 kpc. The data
base consists of 656 radial velocities of globular clusters obtained with
MXU/VLT and GMOS/Gemini, which is the largest sample so far for any galaxy. We
performed a Jeans analysis for a non-rotating isotropic model. An NFW halo with
the parameters r_s = 50 kpc and rho_s = 0.0065 M_sun/pc^3 provides a good
description of our data, fitting well to the X-ray mass. More massive halos are
also permitted that agree with the mass of the Fornax cluster as derived from
galaxy velocities. We compare this halo with the expected MOND models under
isotropy and find that additional dark matter on the order of the stellar mass
is needed to get agreement. A fully radial infinite globular cluster system
would be needed to change this conclusion. Regarding CDM, we cannot draw firm
conclusions. To really constrain a cluster wide halo, more data covering a
larger radius are necessary. The MOND result appears as a small-scale variant
of the finding that MOND in galaxy clusters still needs dark matter.Comment: 4 pages, 2 figures, accepted for publication as a Letter in A&
The mass-dependent star formation histories of disk galaxies: infall model versus observations
We introduce a simple model to explore the star formation histories of disk
galaxies. We assume that the disk origins and grows by continuous gas infall.
The gas infall rate is parametrized by the Gaussian formula with one free
parameter: infall-peak time . The Kennicutt star formation law is adopted
to describe how much cold gas turns into stars. The gas outflow process is also
considered in our model. We find that, at given galactic stellar mass ,
model adopting late infall-peak time results in blue colors, low
metallicity, high specific star formation rate and high gas fraction, while gas
outflow rate mainly influences the gas-phase metallicity and star formation
efficiency mainly influences the gas fraction. Motivated by the local observed
scaling relations, we construct a mass-dependent model by assuming low mass
galaxy has later infall-peak time and larger gas outflow rate than
massive systems. It is shown that this model can be in agreement with not only
the local observations, but also the observed correlations between specific
star formation rate and galactic stellar mass at
intermediate redshift . Comparison between the Gaussian-infall model and
exponential-infall model is also presented. It shows that the
exponential-infall model predicts higher star formation rate at early stage and
lower star formation rate later than that of Gaussian-infall. Our results
suggest that the Gaussian infall rate may be more reasonable to describe the
gas cooling process than the exponential infall rate, especially for low-mass
systems.Comment: 12 pages, 6 figures, ApJ, 2010, 722, 38
Confronting the Minimal Supersymmetric Standard Model with the Study of Scalar Leptons at Future Linear e+e- Colliders
Sleptons can easily be found at future linear e+e- colliders if kinematically
accessible. Measurements of their masses and decay distributions would then
determine MSSM parameters. This paper presents a detailed MC study of the
production and decay of the lighter scalar tau lepton, stau1. We found that
mstau1 and the left-right mixing angle of stau would be measured within an
error of a few percent. tanbeta is determinable in some region of the parameter
space through simultaneous studies of stau1-and selectron-pair production: the
polarization measurement of the tau leptons from stau1 decays and the M1, mchi1
determination using selectron pair production and decay. We also point out the
possibility to determine bino-selectron-e coupling through the measurement of
the angular distribution of the selectron-pair production. The error on the
coupling is expected to be comparable to its typical SUSY radiative correction,
which is proportional to log(msquark/mslepton). The radiative correction
affects M1 and tanbeta determination, necessitating the full 1-loop radiative
correction to the selectron production processes. The implication of these
measurements of the MSSM parameters on selecting models of the origin of
supersymmetry breaking is also discussed.Comment: 35 pages. REVTEX(gzip compressed and uuencoded). Figure are not
included. Text and 15 Figures are available at
http://jlcux1.kek.jp/subg/susy/index-e.html#librar
Comparative differences in musculoskeletal pain consultation and analgesic prescription for people with dementia
Painful musculoskeletal conditions are common in older adults, however pain identification, assessment, and management are reported to be suboptimal for people with dementia. Adequate pain management is an integral aspect of care for people with dementia to prevent or delay negative outcomes, such as behavioural and psychological changes, emergency department attendance, and premature nursing home admission. This study aims to examine musculoskeletal consultations and analgesic prescriptions for people with dementia compared to people without dementia. A dementia cohort (n=36,582) and matched cohort were identified in the Clinical Practice Research Datalink (a UK wide primary care database). Period prevalence for musculoskeletal consultations and analgesic prescriptions were described and logistic regression applied to estimate associations between dementia and musculoskeletal consultation/analgesic prescription from time of dementia diagnosis to 5 years post diagnosis. People with dementia had a consistently (over time) lower prevalence and odds of musculoskeletal consultation and analgesic prescription compared to people without dementia. The evidence suggests that pain management may be suboptimal for people with dementia. These results highlight the need to understand more about practical methods to increase awareness of pain and to employ better methods of pain assessment, evaluation of treatment response and acceptable and effective management for people with dementia, in primary care
Reversible Electrocatalytic Production and Oxidation of Hydrogen at Low Overpotentials by a Functional Hydrogenase Mimic
An efficient ligand combination: A new bis(diphosphine) nickel(II) complex (see picture) is described. A ΔG° value of 0.84 kcal mol^(−1) for hydrogen addition for this complex was calculated from the experimentally determined equilibrium constant. This complex displayed reversible electrocatalytic activity for hydrogen production and oxidation at low overpotentials, which are characteristic for hydrogenase enzymes
Analysis of CP Violation in Neutralino Decays to Tau Sleptons
In the minimal supersymmetric standard model, tau sleptons and neutralinos are expected to be among the
lightest supersymmetric particles that can be produced copiously at future
linear colliders. We analyze pair and production under the assumption , allowing the relevant parameters of
the SUSY Lagrangian to have complex phases. We show that the transverse and
normal components of the polarization vector of the lepton produced in
decays offer sensitive probes of these phases.Comment: LaTeX, 30 pages with 10 .eps figure
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