626 research outputs found
Second-order corrections to neutrino two-flavor oscillation parameters in the wave packet approach
We report about an analytic study involving the {\em intermediate} wave
packet formalism for quantifying the physically relevant information which
appear in the neutrino two-flavor conversion formula and help us to obtain more
precise limits and ranges for neutrino flavor oscillation. By following the
sequence of analytic approximations where we assume a strictly peaked momentum
distribution and consider the second-order corrections in a power series
expansion of the energy, we point out a {\em residual} time-dependent phase
which, coupled with the {\em spreading/slippage} effects, can subtly modify the
neutrino oscillation parameters and limits. Such second-order effects are
usually ignored in the relativistic wave packet treatment, but they present an
evident dependence on the propagation regime so that some small modifications
to the oscillation pattern, even in the ultra-relativistic limit, can be
quantified. These modifications are implemented in the confront with the
neutrino oscillation parameter range (mass-squared difference \Delta m^{\2}
and the mixing-angle ) where we assume the same wave packet parameters
previously noticed in the literature in a kind of {\em toy model} for some
reactor experiments. Generically speaking, our analysis parallels the recent
experimental purposes which concern with higher precision parameter
measurements. To summarize, we show that the effectiveness of a more accurate
determination of \Delta m^{\2} and depends on the wave packet width
and on the averaged propagating energy flux which still
correspond to open variables for some classes of experiments. \Comment: 25 pages, 5 figure
Occurrence of multi-drug resistant tuberculosis among patients with suspected tuberculosis in Katsina State north western Nigeria
Background: A couple of decades ago, experts in the study of Tuberculosis excogitated that multi drug resistant Tuberculosis (MDR-TB) is uncommon in sub-Saharan Africa due to the delayed introduction of rifamycin based regimens. However, previous studies showed that 21% of the global MDR-TB burden occurs in the region; with South Africa, Nigeria and Ethiopia ranking first second and third, respectively.
Aims and objectives: the objective of this study is to determine the prevalence of drug resistant tuberculosis in patients suspected of having tuberculosis. The aims are: to determine the prevalence of MDR-TB in the non HIV patients presenting with persistent cough, to determine the prevalence of MDR-TB in HIV infected patients and to appraise the extent of the association between MDR-TB and HIV in this region.
Methods: Eight hundred and twenty four (824) sputa were collected from suspected participants and analyzed for the presence Mycobacterium tuberculosis and rifampicin resistant strains using a nucleic acid amplification test based machine, Gene expert (Cepheid inc. USA).
Results: One hundred and seventy three (21.0%) of the 824 had MTB and 13(7.5%) of the MTB cases were MDR-TB.
Conclusion: There is a high prevalence of MDR-TB among patients with chronic cough in the region and it is found in both HIV positive and negative patients
Electrical discharge machining of polycrystalline diamond using copper electrode â finishing condition
Research on machining process of Polycrystalline Diamond (PCD) is becoming important as the material was believed suitable to be used for cutting tools of advanced aeronautical structure. Electrical Discharge Machining (EDM) was regarded as the suitable method to machine PCD due its noncontact process nature. The objective of this research is to determine the influence of several EDM parameter such as sparking current, pulse duration, and pulse interval to the material removal rate and surface roughness of the machined PCD. Instead of significantly influenced the material removal rate, the sparking current was also highly influenced tha surface roughness. Highest material removal rate of approximately 0.005mm3/s was recorded by the EDM process with the highest current used of 5A, and lowest pulse interval of 1”s. The influence of pulse duration is not clearly seen at the lowest pulse interval used. On the other hand, 0.4”m was the lowest surface roughness value obtained in this research indicated by the highest sparking current, highest sparking duration and lowest sparking interval of 5A, 1”s and 1”s respectively
A scheme with two large extra dimensions confronted with neutrino physics
We investigate a particle physics model in a six-dimensional spacetime, where
two extra dimensions form a torus. Particles with Standard Model charges are
confined by interactions with a scalar field to four four-dimensional branes,
two vortices accommodating ordinary type fermions and two antivortices
accommodating mirror fermions. We investigate the phenomenological implications
of this multibrane structure by confronting the model with neutrino physics
data.Comment: LATEX, 24 pages, 9 figures, minor changes in the tex
Electrical discharge machining of polycrystalline diamond using copper electrode â finishing condition
Research on machining process of Polycrystalline Diamond (PCD) is becoming important as the material was believed suitable to be used for cutting tools of advanced aeronautical structure. Electrical Discharge Machining (EDM) was regarded as the suitable method to machine PCD due its noncontact process nature. The objective of this research is to determine the influence of several EDM parameter such as sparking current, pulse duration, and pulse interval to the material removal rate and surface roughness of the machined PCD. Instead of significantly influenced the material removal rate, the sparking current was also highly influenced tha surface roughness. Highest material removal rate of approximately 0.005mm3/s was recorded by the EDM process with the highest current used of 5A, and lowest pulse interval of 1”s. The influence of pulse duration is not clearly seen at the lowest pulse interval used. On the other hand, 0.4”m was the lowest surface roughness value obtained in this research indicated by the highest sparking current, highest sparking duration and lowest sparking interval of 5A, 1”s and 1”s respectively
Neutrinoless Double Beta Decay from Singlet Neutrinos in Extra Dimensions
We study the model-building conditions under which a sizeable
-decay signal to the recently reported level of~0.4 eV is due
to Kaluza--Klein singlet neutrinos in theories with large extra dimensions. Our
analysis is based on 5-dimensional singlet-neutrino models compactified on an
orbifold, where the Standard--Model fields are localized on a
3-brane. We show that a successful interpretation of a positive signal within
the above minimal 5-dimensional framework would require a non-vanishing shift
of the 3-brane from the orbifold fixed points by an amount smaller than the
typical scale (100 MeV) characterizing the Fermi nuclear momentum. The
resulting 5-dimensional models predict a sizeable effective Majorana-neutrino
mass that could be several orders of magnitude larger than the light neutrino
masses. Most interestingly, the brane-shifted models with only one bulk sterile
neutrino also predict novel trigonometric textures leading to mass scenarios
with hierarchical active neutrinos and large - and
- mixings that can fully explain the current atmospheric and
solar neutrino data.Comment: 33 pages, LaTeX, minor rewordings, references adde
Protecting the primordial baryon asymmetry in the seesaw model compatible with WMAP and KamLAND
We require that the primordial baryon asymmetry is not washed out in the
seesaw model compatible with the recent results of WMAP and the neutrino
oscillation experiments including the first results of KamLAND. We find that
only the case of the normal neutrino mass hierarchy with an approximate
-symmetry satisfies the requirement. We further derive, depending on the
signs of neutrino mass eigenvalues, three types of neutrino mass matrixes,
where the values of each element are rather precisely fixed.Comment: 21pages; added reference
Suppressing the and neutrino masses by a superconformal force
The idea of Nelson and Strassler to obtain a power law suppression of
parameters by a superconformal force is applied to understand the smallness of
the parameter and neutrino masses in R-parity violating supersymmetric
standard models. We find that the low-energy sector should contain at least
another pair of Higgs doublets, and that a suppression of \lsim O(10^{-13})
for the parameter and neutrino masses can be achieved generically. The
superpotential of the low-energy sector happens to possess an anomaly-free
discrete R-symmetry, either or , which naturally suppresses certain
lepton-flavor violating processes, the neutrinoless double beta decays and also
the electron electric dipole moment. We expect that the escape energy of the
superconformal sector is \lsim O(10) TeV so that this sector will be
observable at LHC. Our models can accommodate to a large mixing among neutrinos
and give the same upper bound of the lightest Higgs mass as the minimal
supersymmetric standard model.Comment: 24 page
Exploring Flavor Structure of Supersymmetry Breaking at B factories
We investigate quark flavor signals in three different supersymmetric models,
the minimal supergravity, the SU(5) SUSY GUT with right handed neutrinos, and
the minimal supersymmetric standard model with U(2) flavor symmetry, in order
to study physics potential of the present and future factories. We evaluate
CP asymmetries in various B decay modes, , ,
and . The allowed regions of the CP asymmetry in
and are different for the three models so that
precise determinations of these observables in near future experiments are
useful to distinguish the three models. We also investigate possible deviations
from the standard model predictions of CP asymmetries in other B decay modes.
In particular, a large deviation is possible for the U(2) model. The
consistency check of the unitarity triangle including , and so on, at future high
luminosity factories and hadronic experiments is therefore
important to distinguish flavor structures of different supersymmetric models.Comment: revtex4, 31 pages, 7 figure
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