410 research outputs found
Direct SUSY dark matter detection-Theoretical rates due to the spin
The recent WMAP data have confirmed that exotic dark matter together with the
vacuum energy (cosmological constant) dominate in the flat Universe. Thus the
direct dark matter detection, consisting of detecting the recoiling nucleus, is
central to particle physics and cosmology. Supersymmetry provides a natural
dark matter candidate, the lightest supersymmetric particle (LSP). The relevant
cross sections arise out of two mechanisms: i) The coherent mode, due to the
scalar interaction and ii) The spin contribution arising from the axial
current. In this paper we will focus on the spin contribution, which is
expected to dominate for light targets.
For both modes it is possible to obtain detectable rates, but in most models
the expected rates are much lower than the present experimental goals. So one
should exploit two characteristic signatures of the reaction, namely the
modulation effect and, in directional experiments, the correlation of the event
rates with the sun's motion.
In standard non directional experiments the modulation is small, less than
two per cent. In the case of the directional event rates we like to suggest
that the experiments exploit two features, of the process, which are
essentially independent of the SUSY model employed, namely: 1) The
forward-backward asymmetry, with respect to the sun's direction of motion, is
very large and 2) The modulation is much larger, especially if the observation
is made in a plane perpendicular to the sun's velocity. In this case the
difference between maximum and minimum can be larger than 40 per cent and the
phase of the Earth at the maximum is direction dependent.Comment: 16 Latex pages, 15 figures, 3 table
Modelling of co-rotating twin-screw extruders in the pharmaceutical industry I : single component model
Twin-screw extruders are being increasingly applied in the pharmaceutical industry for the manufacture of solid dispersions. In particular, Hot Melt Extrusion (HME) is a viable manufacturing alternative for poorly soluble drugs that are difficult to process. This is due to the high shear stress applied in the process, which enhances mixing of the base polymer with the dispersed API. Delivery systems that can be obtained using this technology include pellets, granules, sustained release tablets and implants. Experiments for HME are typically very labour-intensive, involving the use of highly viscous polymers, high pressures, and require proper cleaning between runs. Identifying the critical experiments to perform based on model simulations would thus be highly desirable. Single-component modelling of twin-screw extrusion processes could be beneficial in the following areas: identifying optimal screw configurations, tracking the degree of melting and when identifying the area within the extruder where the polymer becomes completely melted
The iron-sulfur helicase DDX11 promotes the generation of single-stranded DNA for CHK1 activation
The iron-sulfur (FeS) cluster helicase DDX11 is associated with a human disorder termed Warsaw Breakage Syndrome. Interestingly, one disease-associated mutation affects the highly conserved arginine-263 in the FeS cluster-binding motif. Here, we demonstrate that the FeS cluster in DDX11 is required for DNA binding, ATP hydrolysis, and DNA helicase activity, and that arginine-263 affects FeS cluster binding, most likely because of its positive charge. We further show that DDX11 interacts with the replication factors DNA polymerase delta and WDHD1. In vitro, DDX11 can remove DNA obstacles ahead of Pol δ in an ATPase- and FeS domain-dependent manner, and hence generate single-stranded DNA. Accordingly, depletion of DDX11 causes reduced levels of single-stranded DNA, a reduction of chromatin-bound replication protein A, and impaired CHK1 phosphorylation at serine-345. Taken together, we propose that DDX11 plays a role in dismantling secondary structures during DNA replication, thereby promoting CHK1 activation
Scaling law for the electromagnetic form factors of the proton
The violation of the scaling law for the electric and magnetic form factors
of the proton are examined within the cloudy bag model. The suppression of the
ratio of the electric and magnetic form factors is natural in the bag model.
The pion cloud plays a moderate role in understanding the recent data from
TJNAF.Comment: 8 pages, REVTeX, 2 figures include
Antimicrobial susceptibility pattern of urine culture isolates in a tertiary care hospital of Jharkhand, India
Background: Urinary tract infection (UTI) is one of the common infections encountered by the clinicians. Though a good number of antimicrobial agents are available, still UTIs have become difficult to treat due to development of resistance by the uropathogens. So, regional data regarding the common uropathogens and their sensitivity pattern is required to guide the clinicians to start empirical therapy while managing UTIs. The purpose of the study was to identify different species of microorganisms, along with their antimicrobial susceptibility pattern, causing urinary tract infection in outpatient and indoor patients at RIMS, Ranchi, Jharkhand.Methods: Observational study was conducted using urine culture and sensitivity reports collected retrospectively from records maintained in the department of Microbiology over a period from July 2016 to Feb 2017 in tertiary care hospital.Results: UTI was more common in females (57.74%) than in males (42.26%). Among the uropathogens isolated Escherichia coli (37.41%) was found to be the predominant organism followed by Klebsiella species (32.79%), Pseudomonas species (25.86%), and gram-positive bacteria Staphylococcus aureus accounted (3.92%) of total cases. The most common isolates were E. coli showed high sensitivity to amikacin (79.24%), followed by levofloxacin (77.21%) and gentamycin (62.26%). It was found to be resistant to norfloxacin (86%), nalidixic acid (86.76%) and cefotaxime (69.88%).Conclusions: Though various microorganisms are responsible for UTI. Escherichia coli species is the most common organism. Antimicrobial resistance has already emerged against many antibiotics, making empirical treatment of these infections challenging
On the Nucleon Distribution Amplitude: The Heterotic Solution
We present a new nucleon distribution amplitude which amalgamates features of
the Chernyak-Ogloblin-Zhitnitsky model with those of the Gari-Stefanis model.
This "heterotic" solution provides the possibility to have asymptotically a
small ratio \hbox{}, while fulfilling
most of the sum-rule requirements up to the third order. Using this nucleon
distribution amplitude we calculate the electromagnetic and weak nucleon form
factors, the transition form factor and the decay widths
of the charmonium levels , , and into .
The agreement with the available data is remarkable in all cases.Comment: 15 pages, RUB-TPII-21/92 Preprin
Nucleon Charge and Magnetization Densities from Sachs Form Factors
Relativistic prescriptions relating Sachs form factors to nucleon charge and
magnetization densities are used to fit recent data for both the proton and the
neutron. The analysis uses expansions in complete radial bases to minimize
model dependence and to estimate the uncertainties in radial densities due to
limitation of the range of momentum transfer. We find that the charge
distribution for the proton is significantly broad than its magnetization
density and that the magnetization density is slightly broader for the neutron
than the proton. The neutron charge form factor is consistent with the Galster
parametrization over the available range of Q^2, but relativistic inversion
produces a softer radial density. Discrete ambiguities in the inversion method
are analyzed in detail. The method of Mitra and Kumari ensures compatibility
with pQCD and is most useful for extrapolating form factors to large Q^2.Comment: To appear in Phys. Rev. C. Two new figures and accompanying text have
been added and several discussions have been clarified with no significant
changes to the conclusions. Now contains 47 pages including 21 figures and 2
table
New calculations of the PNC Matrix Element for the 0 doublet in N
A new calculation of the predominantly isoscalar PNC matrix element between
the (E 8.7 MeV) states in N has
been carried out in a (0+1+2+3+4) model space with the
Warburton-Brown interaction. The magnitude of the PNC matrix element of 0.22 to
0.34 eV obtained with the DDH PNC interaction is substantially suppressed
compared with previous calculations in smaller model spaces but shows agreement
with the preliminary Seattle experimental data. The calculated sign is opposite
to that obtained experimentally, and the implications of this are discussed.Comment: REVTEX, 28 page
Parity Mixed Doublets in A = 36 Nuclei
The -circular polarizations () and asymmetries
() of the parity forbidden M1 + E2 -decays: MeV) and MeV)
MeV) are investigated theoretically. We use the recently proposed
Warburton-Becker-Brown shell-model interaction. For the weak forces we discuss
comparatively different weak interaction models based on different assumptions
for evaluating the weak meson-hadron coupling constants. The results determine
a range of values from which we find the most probable values:
= for and = for .Comment: RevTeX, 17 pages; to appear in Phys. Rev.
The Separable Kernel of Nucleon-Nucleon Interaction in the Bethe-Salpeter Approach
The dispersion relations for nucleon-nucleon (NN) T-matrix in the framework
of Bethe-Salpeter equation for two spin one-half particle system and with
separable kernel of interaction are considered in the paper. The developed
expressions are applied for construction of the separable kernel of interaction
for S partial-waves in singlet and triplet channels. We calculate the low
energy scattering parameters and the phase shifts and also the deuteron binding
energy with the separable interaction. The approach can be easily extended to
higher partial-waves for NN-scattering and other reactions (anti N N-, pi
N-scattering).Comment: RevTex 4 style, 9 pages, 1 figur
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