9,133 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
COMPARATIVE EVALUATION OF ANTIOXIDANT ACTIVITY OF SUBSTITUTED FLAVONES
  Objective: The flavonoids are a heterogeneous group of plant polyphenols that are endowed with several biological activities including antioxidant, anti-inflammatory, immunomodulatory, antiviral, antimutagenic, and anticarcinogenic properties. They are believed to interfere with the various free radical-producing systems and they also enhance the functions of endogenous antioxidants. The aim of this study was to compare the antioxidant activity of synthesized substituted flavones by various free radical scavenging assays.Methods: The flavones used in the study, 6,3',4' - trihydroxy flavones (THF) and 3-hydroxy-6,3'-dimethoxy flavones were synthesized using standard procedures and their antioxidant activity was compared by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, hydrogen peroxide scavenging assay, hydroxyl radical scavenging assay, reducing power capacity, superoxide free radical scavenging assay, and 2,2′-azino-bis-3-ethylbenzthiazoline-6- sulphonic acid assay.Results: In the DPPH assay, THF has an inhibitory concentration 50% value of 18.89 μg/ml which was much better than that of standard ascorbic acid which was 26.1 μg/ml. The THF had a much better antioxidant activity in most of the free radical scavenging assays.Conclusion: From the study, it can be seen that the flavones showed significant antioxidant activity that can be used for treatment of various disease
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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