8,880 research outputs found
On the Generalised Pauli--Villars Regularization of the Standard Model
We show that the regularization of the Standard Model proposed by Frolov and
Slavnov describes a nonlocal theory with quite simple Lagrangian.Comment: 7 pages, harvma
Nonlocal effects in the shot noise of diffusive superconductor - normal-metal systems
A cross-shaped diffusive system with two superconducting and two normal
electrodes is considered. A voltage is applied between the normal
leads. Even in the absence of average current through the superconducting
electrodes their presence increases the shot noise at the normal electrodes and
doubles it in the case of a strong coupling to the superconductors. The
nonequilibrium noise at the superconducting electrodes remains finite even in
the case of a vanishingly small transport current due to the absence of energy
transfer into the superconductors. This noise is suppressed by
electron-electron scattering at sufficiently high voltages.Comment: 4 pages, RevTeX, 2 eps figure
Parametric investigation of nonlinear fluctuations in a dc glow discharge plasma
Glow discharge plasmas exhibit various types of self excited oscillations for
different initial conditions like discharge voltages and filling pressures. The
behavior of such oscillations associated with the anode glow have been
investigated using nonlinear techniques like correlation dimension, largest
Lyapunov exponent etc. It is seen that these oscillations go to an ordered
state from a chaotic state with increase in input energy i.e. with discharge
voltages implying occurrence of inverse bifurcations. These results are
different from the other observations wherein the fluctuations have been
observed to go from ordered to chaotic state.Comment: Submitted to Chao
In silico estimates of the free energy rates in growing tumor spheroids
The physics of solid tumor growth can be considered at three distinct size
scales: the tumor scale, the cell-extracellular matrix (ECM) scale and the
sub-cellular scale. In this paper we consider the tumor scale in the interest
of eventually developing a system-level understanding of the progression of
cancer. At this scale, cell populations and chemical species are best treated
as concentration fields that vary with time and space. The cells have
chemo-mechanical interactions with each other and with the ECM, consume glucose
and oxygen that are transported through the tumor, and create chemical
byproducts. We present a continuum mathematical model for the biochemical
dynamics and mechanics that govern tumor growth. The biochemical dynamics and
mechanics also engender free energy changes that serve as universal measures
for comparison of these processes. Within our mathematical framework we
therefore consider the free energy inequality, which arises from the first and
second laws of thermodynamics. With the model we compute preliminary estimates
of the free energy rates of a growing tumor in its pre-vascular stage by using
currently available data from single cells and multicellular tumor spheroids.Comment: 27 pages with 5 figures and 2 tables. Figures and tables appear at
the end of the pape
Molecular analysis of isoniazid-resistant clinical isolates of Mycobacterium tuberculosis from India
The presence of mutations in specific regions of katG, inhA, oxyR–ahpC and kasA associated with isoniazid (INH)-resistant clinical isolates
of Mycobacterium tuberculosis from India were analysed by DNA sequencing. Point mutations in the katG gene at codon 315 and a mutation
at codon 138 were detected in 64.3% (45/70) and 4% (1/25) of isolates, respectively. Polymorphisms at codon 463 of the katG gene were
found both in resistant and sensitive isolates. Mutation at the inhA and oxyR–ahpC promoter regions occurred in 11.4% (8/70) and 35.0%
(14/40) of the isolates, respectively. No mutation was found to occur in kasA and inhA structural gene regions. Of the 70 resistant isolates
studied, 55 (78.6%) showed mutation in the regions sequenced. This is the first comprehensive molecular analysis of INH resistance in India,
which suggests that point mutation rather than deletion and insertion is the major cause of INH resistance
Observation of narrow fluorescence from doubly driven four-level atoms at room temperature
Unusually narrow fluorescence peaks are seen from Rubidium-85 atoms under the
action of two driving laser fields that are in a three dimensional molasses
configuration. One of the lasers is held at a fixed detuning from the "cooling"
transition, while the other is scanned across the "repumping" transitions. The
fluorescence peaks are split into symmetric pairs, with the seperation within a
pair increasing with the detuning of the cooling laser. For large detunings
additional small peaks are seen. A simple model is proposed to explain these
experimental observations.Comment: 8 pages, 4 figures, needs epl.cl
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