6,271 research outputs found
First Order Calculation of the Inclusive Cross Section pp to ZZ by Graviton Exchange in Large Extra Dimensions
We calculate the inclusive cross section of double Z-boson production within
large extra dimensions at the Large Hadron Collider (LHC). Using perturbatively
quantized gravity in the ADD model we perform a first order calculation of the
graviton mediated contribution to the pp to ZZ cross section. At low energies
(e.g. Tevatron) this additional contribution is very small, making it virtually
unobservable, for a fundamental mass scale above 2500 GeV. At LHC energies
however, the calculation indicates that the ZZ-production rate within the ADD
model should differ significantly from the Standard Model if the new
fundamental mass scale would be below 15000 GeV. A comparison with the observed
production rate at the LHC might therefore provide direct hints on the number
and structure of the extra dimensions.Comment: 7 pages, 7 figures, accepted for publication in Phys. Rev.
Southern Hemisphere automated supernova search
The Perth Astronomy Research Group has developed an automated supernova search program, using the 61 cm Perth–Lowell reflecting telescope at Perth Observatory in Western Australia, equipped with a CCD camera. The system is currently capable of observing about 15 objects per hour, using 3 min exposures, and has a detection threshold of 18th–19th magnitude. The entire system has been constructed using low‐cost IBM‐compatible computers. Two original discoveries (SN 1993K, SN 1994R) have so far been made during automated search runs. This paper describes the hardware and software used for the supernova search program, and shows some preliminary results from the search system
A study of rotating globular clusters - the case of the old, metal-poor globular cluster NGC 4372
Aims: We present the first in-depth study of the kinematic properties and
derive the structural parameters of NGC 4372 based on the fit of a Plummer
profile and a rotating, physical model. We explore the link between internal
rotation to different cluster properties and together with similar studies of
more GCs, we put these in the context of globular cluster formation and
evolution. Methods: We present radial velocities for 131 cluster member stars
measured from high-resolution FLAMES/GIRAFFE observations. Their membership to
the GC is additionally confirmed from precise metallicity estimates. Using this
kinematic data set we build a velocity dispersion profile and a systemic
rotation curve. Additionally, we obtain an elliptical number density profile of
NGC 4372 based on optical images using a MCMC fitting algorithm. From this we
derive the cluster's half-light radius and ellipticity as r_h=3.4'+/-0.04' and
e=0.08+/-0.01. Finally, we give a physical interpretation of the observed
morphological and kinematic properties of this GC by fitting an axisymmetric,
differentially rotating, dynamical model. Results: Our results show that NGC
4372 has an unusually high ratio of rotation amplitude to velocity dispersion
(1.2 vs. 4.5 km/s) for its metallicity. This, however, puts it in line with two
other exceptional, very metal-poor GCs - M 15 and NGC 4590. We also find a mild
flattening of NGC 4372 in the direction of its rotation. Given its old age,
this suggests that the flattening is indeed caused by the systemic rotation
rather than tidal interactions with the Galaxy. Additionally, we estimate the
dynamical mass of the GC M_dyn=2.0+/-0.5 x 10^5 M_Sun based on the dynamical
model, which constrains the mass-to-light ratio of NGC 4372 between 1.4 and 2.3
M_Sun/L_Sun, representative of an old, purely stellar population.Comment: Accepted for publication in A&A, 12 pages, 14 figures, 2 table
The Effect of Movement Therapy on Negative Symptoms in Schizophrenia - A Multicenter Randomized Controlled Trial
Objective: Negative symptoms of patients with Schizophrenia are resistant to
medical treatment or conventional group therapy. Understanding schizophrenia
as a form of disembodiment of the self, a number of scientists have argued
that the approach of embodiment and associated embodied therapies, such as
Dance and Movement Therapy (DMT) or Body Psychotherapy (BPT), may be more
suitable to explain the psychopathology underlying the mental illness and to
address its symptoms. Hence the present randomized controlled trial
(DRKS00009828, http://apps.who.int/trialsearch/) aimed to examine the
effectiveness of manualized movement therapy (BPT/DMT) on the negative
symptoms of patients with schizophrenia. Method:A total of 68 out-patients
with a diagnosis of a schizophrenia spectrum disorder were randomly allocated
to either the treatment (n = 44, 20 sessions of BPT/DMT) or the control
condition [n = 24, treatment as usual (TAU)]. Changes in negative symptom
scores on the Scale for the Assessment of Negative Symptoms (SANS) were
analyzed using Analysis of Covariance (ANCOVA) with Simpson-Angus Scale (SAS)
scores as covariates in order to control for side effects of antipsychotic
medication. Results:After 20 sessions of treatment (BPT/DMT or TAU), patients
receiving movement therapy had significantly lower negative symptom scores
(SANS total score, blunted affect, attention). Effect sizes were moderate and
mean symptom reduction in the treatment group was 20.65%. Conclusion:The study
demonstrates that embodied therapies, such as BPT/DMT, are highly effective in
the treatment of patients with schizophrenia. Results strongly suggest that
BPT/DMT should be embedded in the daily clinical routine
Observer design for a nonlinear heat equation: Application to semiconductor wafer processing
In this paper, the problem of observer design for a class of 1D nonlinear heat equations with pointwise in-domain temperature measurements is addressed. A pointwise measurement injection observer is designed and the robust convergence of its estimation error in presence of bounded distributed perturbations is established by verifying input-to-state stability. The obtained convergence conditions express the underlying interplay between heat conduction and radiation and include specific dependencies on the sensor locations which are the main degrees of freedom in the design approach. The theoretical results are experimentally validated on a semiconductor wafer processing unit
Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies
We present metallicity distribution functions (MDFs) for the central regions
of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II,
Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the
published catalog of abundance measurements from the previous paper in this
series. The measurements are based on spectral synthesis of iron absorption
lines. For each MDF, we determine maximum likelihood fits for Leaky Box,
Pre-Enriched, and Extra Gas (wherein the gas supply available for star
formation increases before it decreases to zero) analytic models of chemical
evolution. Although the models are too simplistic to describe any MDF in
detail, a Leaky Box starting from zero metallicity gas fits none of the
galaxies except Canes Venatici I well. The MDFs of some galaxies, particularly
the more luminous ones, strongly prefer the Extra Gas Model to the other
models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly
better than the Extra Gas Model. The best-fit effective yields of the less
luminous half of our galaxy sample do not exceed 0.02 Z_sun, indicating that
gas outflow is important in the chemical evolution of the less luminous
galaxies. We surmise that the ratio of the importance of gas infall to gas
outflow increases with galaxy luminosity. Strong correlations of average [Fe/H]
and metallicity spread with luminosity support this hypothesis.Comment: 17 pages, 5 figures; accepted for publication in ApJ; minor
corrections in v3; corrected typographical errors in Tables 1 and 3 in v
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