3,754 research outputs found
Canonical Constraints on Leptonic Cp Violation using UHCR neutrino fluxes
It is shown that one can in principle constrain the CP-violating parameter
delta from measurements of four independant |V_{ij}|^2, or three of them and a
ratio, in the leptonic sector. To quantify our approach, using unitarity, we
derive simple expressions in terms of four independant |V_{ij}|^2 for
cos(delta) and an expression for sin^2(delta) from J^2. Thus, depending on the
values of |V_{ij}| and their accuracy, we can set meaningful limits on |delta|.
To illustrate numerically, if |V_{u1}|^2 is close to 0.1 with a 10% precision,
and if |V_{e3}^2 is larger than 0.005 and for values of |V_{e2}|^2 and
|V_{u3}|^2 that stay within +-0.1 of the current experimental data leads to a
bound pi/2 < |delta| < pi. Alternatively, a certain combination of parameters
with values of |V_{e3}|^2 larger than 0.01 leads to a closed bound of 73 <
|delta| < 103. In general, we find that it is better to use |V_{u1}|^2 or
|V_{t1}|^2 as the fourth independant |V_{ij}|^2 and that over most of the
parameter space, delta is least sensitive to |V_{e3}|^2. With just three
independant measurements (solar, atmospheric and reactor) it is impossible to
set limits on the CP phase. In this respect, we study the use of ultra high
energy cosmic (UHCR) neutrino fluxes as the additional fourth information. We
find that within the SM, neutrino fluxes of all three flavours will be very
similar but that pushing current neutrino data to their extreme values still
allowed, ratios of cosmic neutrino fluxes can differ by up to 20%; such large
discrepancies could imply negligibly small CP-violation. We also study a non
radiative neutrino decay model and find that the neutrino fluxes can differ by
a factor of up to 3 within this model and that an accuracy of 10% on the
neutrino fluxes is sufficient to set interestin limits on delta.Comment: 8 pages, 2 figures, 5 table
Achieving Efficient Strong Scaling with PETSc using Hybrid MPI/OpenMP Optimisation
The increasing number of processing elements and decreas- ing memory to core
ratio in modern high-performance platforms makes efficient strong scaling a key
requirement for numerical algorithms. In order to achieve efficient scalability
on massively parallel systems scientific software must evolve across the entire
stack to exploit the multiple levels of parallelism exposed in modern
architectures. In this paper we demonstrate the use of hybrid MPI/OpenMP
parallelisation to optimise parallel sparse matrix-vector multiplication in
PETSc, a widely used scientific library for the scalable solution of partial
differential equations. Using large matrices generated by Fluidity, an open
source CFD application code which uses PETSc as its linear solver engine, we
evaluate the effect of explicit communication overlap using task-based
parallelism and show how to further improve performance by explicitly load
balancing threads within MPI processes. We demonstrate a significant speedup
over the pure-MPI mode and efficient strong scaling of sparse matrix-vector
multiplication on Fujitsu PRIMEHPC FX10 and Cray XE6 systems
Radiative stability of neutrino-mass textures
Neutrino-mass textures proposed at high-scales are known to be unstable
against radiative corrections especially for nearly degenerate eigen values.
Within the renormalization group constraints we find a mechanism in a class of
gauge theories which guarantees reproduction of any high-scale texture at low
energies with radiative stability. We also show how the mechanism explains
solar and atmospheric neutrino anomalies through the bimaximal texture at high
scale.Comment: 4 pages REVTEX, 1 Postscript fi
New Approach to Implement Authentication and Key Distribution on WI-Max Networks
Wi-Max is utilized for the remote system. This innovation will be a developing innovation for remote innovation in future. It is like Wi-Fi however its territory of scope and transfer speed is considerably higher than the Wi-Fi. So the security turns out to be vital issue. Wi-Max innovation incorporates some security components, for example, Key administration, Authentication and privacy. For security first need is crosswise over remote system and other is to give get to control to the system and the get to control can be given utilizing access control conventions. Major issues are in WiMax difficult to handle the security problems. In this paper proposed implementing authentication and distribution of keys in secure manner on open networks and also providing confidentiality
Neuropeptides and peptide hormones in syncope and orthostatic intolerance
Syncope and orthostatic intolerance (OI) are common clinical syndromes often requiring medical attention. The former is defined as transient loss of consciousness and postural tone due to self-limited cerebral hypoperfusion, while the latter consists of inappropriate cardiovascular responses to upright posture such as occur with orthostatic hypotension (OH) or postural orthostatic tachycardia syndrome. The most frequent causes of syncope and OI are conditions that temporarily disrupt essential moment-to-moment interaction between the autonomic nervous system and cardiovascular system. In this regard, many neuropeptides (NPs) or peptide hormones (PH) exert cardioactive effects that might contribute to the pathophysiology of certain forms of syncope or OI. To date, the principal peptides that have been studied in this context are: atrial and B-type-neuropeptides, adrenomedullin, endothelin-1 (ET-1), galanin, and vasopressin. While definitive conclusions cannot yet be drawn, the intrinsic vasoconstrictor ET-1 appears to be elevated in OH, presumably to compensate for vasodilation and hypotension of other etiologies. As such elevated ET-1 may become a marker for OH. Further, elevated NT-proBNP may play a role in causing vasodilation and hypotension in some forms of OH of previously unknown cause, and may be a marker in other patients of a cardiovascular cause of syncope and OI. In the end, the study of the role of NPs and PHs in syncope and OI syndromes is at an early stage, and considerable further future effort is needed
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