35,629 research outputs found
Interferometer Response to Scalar Gravitational Waves
It was recently suggested that the magnetic component of Gravitational Waves
(GWs) is relevant in the evaluation of frequency response functions of
gravitational interferometers. In this paper we extend the analysis to the
magnetic component of the scalar mode of GWs which arise from scalar-tensor
gravity theory. In the low-frequency approximation, the response function of
ground-based interferometers is calculated. The angular dependence of the
electric and magnetic contributions to the response function is discussed.
Finally, for an arbitrary frequency range, the proper distance between two test
masses is calculated and its usefulness in the high-frequency limit for
space-based interferometers is briefly considered.Comment: Accepted for publication by Int. Journ. Mod. Phys. D. Final versio
On the degree conjecture for separability of multipartite quantum states
We settle the so-called degree conjecture for the separability of
multipartite quantum states, which are normalized graph Laplacians, first given
by Braunstein {\it et al.} [Phys. Rev. A \textbf{73}, 012320 (2006)]. The
conjecture states that a multipartite quantum state is separable if and only if
the degree matrix of the graph associated with the state is equal to the degree
matrix of the partial transpose of this graph. We call this statement to be the
strong form of the conjecture. In its weak version, the conjecture requires
only the necessity, that is, if the state is separable, the corresponding
degree matrices match. We prove the strong form of the conjecture for {\it
pure} multipartite quantum states, using the modified tensor product of graphs
defined in [J. Phys. A: Math. Theor. \textbf{40}, 10251 (2007)], as both
necessary and sufficient condition for separability. Based on this proof, we
give a polynomial-time algorithm for completely factorizing any pure
multipartite quantum state. By polynomial-time algorithm we mean that the
execution time of this algorithm increases as a polynomial in where is
the number of parts of the quantum system. We give a counter-example to show
that the conjecture fails, in general, even in its weak form, for multipartite
mixed states. Finally, we prove this conjecture, in its weak form, for a class
of multipartite mixed states, giving only a necessary condition for
separability.Comment: 17 pages, 3 figures. Comments are welcom
Coherent States on Hilbert Modules
We generalize the concept of coherent states, traditionally defined as
special families of vectors on Hilbert spaces, to Hilbert modules. We show that
Hilbert modules over -algebras are the natural settings for a
generalization of coherent states defined on Hilbert spaces. We consider those
Hilbert -modules which have a natural left action from another
-algebra say, . The coherent states are well defined in this
case and they behave well with respect to the left action by .
Certain classical objects like the Cuntz algebra are related to specific
examples of coherent states. Finally we show that coherent states on modules
give rise to a completely positive kernel between two -algebras, in
complete analogy to the Hilbert space situation. Related to this there is a
dilation result for positive operator valued measures, in the sense of Naimark.
A number of examples are worked out to illustrate the theory
Hawking Radiation via Tunneling from Hot NUT-Kerr-Newman-Kasuya Spacetime
We study the Hawking thermal spectrum in dragging coordinate system and the
tunneling radiation characteristics of hot NUT-Kerr-Newman-Kasuya spacetime.
The tunneling rates at the event and cosmological horizon are found to be
related to the change of Bekenstein-Hawking entropy. The radiation spectrum is
not pure thermal and thus there is a correction to the Hawking thermal
spectrum.Comment: To appear in Class. Quant. Gra
Reconfiguration with Simultaneous DG Installation to Improve the Voltage Profile in Distribution Network Using Harmony Search Algorithm
Due to dynamic nature of loads, total system load is more than its generation capacity that makes relieving of load on the feeders not possible and hence voltage profile of the system will not be improved to the required level. In order to meet required level of load demand, Reconfiguration & DG units are integrated in distribution network to improve voltage profile, to provide reliable and uninterrupted power supply and also to achieve economic benefits such as minimum power loss, energy efficiency and load leveling. This work proposes minimization of real power losses and improvement of voltage profile using network reconfiguration in the presence of distributed generation. Generally distributed generations (DG) are preferred with objective of minimizing real power loss and improving voltage profile in distribution system. In this work A meta heuristic Harmony Search Algorithm (HSA) is used to simultaneously reconfigure and identify the optimal locations for installation of DG units in a distribution network. Sensitivity analysis is used to identify optimal locations for installation of DG units. The proposed method has tested in MATLAB for 33-bus and 69- Bus radial distribution systems at three different load levels and the analysis is presented for loss minimization
Radiative and Semileptonic B Decays Involving Higher K-Resonances in the Final States
We study the radiative and semileptonic B decays involving a spin-
resonant with parity for and for
in the final state. Using the large energy effective theory (LEET)
techniques, we formulate transition form factors in the large
recoil region in terms of two independent LEET functions
and , the values of
which at zero momentum transfer are estimated in the BSW model. According to
the QCD counting rules, exhibit a dipole
dependence in . We predict the decay rates for ,
and . The
branching fractions for these decays with higher -resonances in the final
state are suppressed due to the smaller phase spaces and the smaller values of
. Furthermore, if the spin of
becomes larger, the branching fractions will be further suppressed due to the
smaller Clebsch-Gordan coefficients defined by the polarization tensors of the
. We also calculate the forward backward asymmetry of the decay, for which the zero is highly insensitive to the
-resonances in the LEET parametrization.Comment: 27 pages, 4 figures, 7 tables;contents and figures corrected, title
and references revise
Lepton number violating four-body tau lepton decays
We study the four-body tau^+- -> nu_tau l^+- l^+- X^-+ decays where l=e or mu
and X=pi, K, rho and K^* mesons. These decay processes violate the total lepton
number (|Delta L|=2) and can be induced by the exchange of Majorana neutrinos.
We consider an scenario where these decays are dominated by the exchange of
only one heavy neutrino which produces an enhancement of the decay amplitude
via the resonant mechanism. Searches for these novel decay channels with
branching fractions sensitivities of (10^-7) can provide constraints on the
parameter space of the Majorana neutrinos which are stronger than the ones
obtained from Delta L=2 decays of charged pseudoscalar mesons.Comment: REVTeX, 14 pages, 6 figures, four references added. Version accepted
for publication in PR
Effect of a tumour-produced lipid-mobilizing factor on protein synthesis and degradation
Treatment of murine myoblasts, myotubes and tumour cells with a tumour-produced lipid mobilizing factor (LMF), caused a concentration-dependent stimulation of protein synthesis, within a 24 h period. There was no effect on cell number or [3H] thymidine incorporation, but a similar concentration-dependent stimulation of 2-deoxyglucose uptake. LMF produced an increase in intracellular cyclic AMP levels, which was linearly (r2= 0.973) related to the increase in protein synthesis. The effect of LMF was attenuated by the adenylate cyclase inhibitor MDL 12330A, and was additive with the stimulation produced by forskolin. Both propranolol (10 μM) and the specific β3-adrenergic receptor antagonist SR 59230A (10–5M), significantly reduced the stimulation of protein synthesis induced by LMF. Protein synthesis was also increased by 69% (P = 0.006) in soleus muscles of mice administered LMF, while there was a 26% decrease in protein degradation (P = 0.03). While LMF had no effect on the lysosomal enzymes, cathepsins B and L, there was a decrease in proteasome activity, as determined both by the ‘chymotrypsin-like’ enzyme activity, as well as expression of proteasome α-type subunits, determined by Western blotting. These results show that in addition to its lipid-mobilizing activity LMF also increases protein accumulation in skeletal muscle both by an increase in protein synthesis and a decrease in protein catabolism. © 2001 Cancer Research Campaign http://www.bjcancer.co
- …