8,759 research outputs found
Uncertainty Principle of Morgan type and Schr\"odinger Evolutions
We prove unique continuation properties for solutions of evolution
Schr\"odinger equation with time dependent potentials. In the case of the free
solution these correspond to uncertainly principles referred to as being of
Morgan type. As an application of our method we also obtain results concerning
the possible concentration profiles of solutions of semi-linear Schr\"odinger
equations
Data reduction in the ITMS system through a data acquisition model with self-adaptive sampling rate
Long pulse or steady state operation of fusion experiments require data acquisition and processing systems that reduce the volume of data involved. The availability of self-adaptive sampling rate systems and the use of real-time lossless data compression techniques can help solve these problems. The former is important for continuous adaptation of sampling frequency for experimental requirements. The latter allows the maintenance of continuous digitization under limited memory conditions. This can be achieved by permanent transmission of compressed data to other systems. The compacted transfer ensures the use of minimum bandwidth. This paper presents an implementation based on intelligent test and measurement system (ITMS), a data acquisition system architecture with multiprocessing capabilities that permits it to adapt the system’s sampling frequency throughout the experiment. The sampling rate can be controlled depending on the experiment’s specific requirements by using an external dc voltage signal or by defining user events through software. The system takes advantage of the high processing capabilities of the ITMS platform to implement a data reduction mechanism based in lossless data compression algorithms which are themselves based in periodic deltas
Event Recognition Using Signal Spectrograms in Long Pulse Experiments
As discharge duration increases, real-time complex analysis of the signal becomes more important. In this context, data acquisition and processing systems must provide models for designing experiments which use event oriented plasma control. One example of advanced data analysis is signal classification. The off-line statistical analysis of a large number of discharges provides information to develop algorithms for the determination of the plasma parameters from measurements of magnetohydrodinamic waves, for example, to detect density fluctuations induced by the Alfvén cascades using morphological patterns. The need to apply different algorithms to the signals and to address different processing algorithms using the previous results necessitates the use of an event-based experiment. The Intelligent Test and Measurement System platform is an example of architecture designed to implement distributed data acquisition and real-time processing systems. The processing algorithm sequence is modeled using an event-based paradigm. The adaptive capacity of this model is based on the logic defined by the use of state machines in SCXML. The Intelligent Test and Measurement System platform mixes a local multiprocessing model with a distributed deployment of services based on Jini
Vacuum stability conditions of the economical 3-3-1 model from copositivity
By applying copositivity criterion to the scalar potential of the economical
model, we derive necessary and sufficient bounded-from-below conditions
at tree level. Although these are a large number of intricate inequalities for
the dimensionless parameters of the scalar potential, we present general
enlightening relations in this work. Additionally, we use constraints coming
from the minimization of the scalar potential by means of the orbit space
method, the positivity of the squared masses of the extra scalars, the Higgs
boson mass, the gauge boson mass and its mixing angle with the SM
boson in order to further restrict the parameter space of this model.Comment: 22 pages, 7 figures, added text and references. Matches published
versio
Cosmological evolution of warm dark matter fluctuations II: Solution from small to large scales and keV sterile neutrinos
We solve the cosmological evolution of warm dark matter (WDM) density
fluctuations with the Volterra integral equations of paper I. In the absence of
neutrinos, the anisotropic stress vanishes and the Volterra equations reduce to
a single integral equation. We solve numerically this equation both for DM
fermions decoupling at equilibrium and DM sterile neutrinos decoupling out of
equilibrium. We give the exact analytic solution for the density fluctuations
and gravitational potential at zero wavenumber. We compute the density contrast
as a function of the scale factor a for a wide range of wavenumbers k. At fixed
a, the density contrast grows with k for k
k_c, (k_c ~ 1.6/Mpc). The density contrast depends on k and a mainly through
the product k a exhibiting a self-similar behavior. Our numerical density
contrast for small k gently approaches our analytic solution for k = 0. For
fixed k < 1/(60 kpc), the density contrast generically grows with a while for k
> 1/(60 kpc) it exhibits oscillations since the RD era which become stronger as
k grows. We compute the transfer function of the density contrast for thermal
fermions and for sterile neutrinos in: a) the Dodelson-Widrow (DW) model and b)
in a model with sterile neutrinos produced by a scalar particle decay. The
transfer function grows with k for small k and then decreases after reaching a
maximum at k = k_c reflecting the time evolution of the density contrast. The
integral kernels in the Volterra equations are nonlocal in time and their
falloff determine the memory of the past evolution since decoupling. This
falloff is faster when DM decouples at equilibrium than when it decouples out
of equilibrium. Although neutrinos and photons can be neglected in the MD era,
they contribute in the MD era through their memory from the RD era.Comment: 27 pages, 6 figures. To appear in Phys Rev
Age-related changes of the noradrenergic and acetylcholinesterase reactive nerve fibres innervating the pigeon bursa of Fabricius.
Age-dependent changes in the innervation of the pigeon (Columba livia, L.) bursa of Fabricius, from hatching to 120 days of age, were studied by fluorescence-histochemical and neurochemical methods for demonstrating noradrenergic and acetylcholinesterase (AChE)-reactive nerve fibres respectively. The distribution of both nerve fibre types was largely perivascular. Furthermore, a few isolated nerve fiber profiles were observed beneath the bursal epithelium, in the interfollicular septa and in the follicular cortex. No nerve fibre profiles reaching the medulla of the lymphoid follicles were observed. In addition to nerve fibres, AChE reactive neuron-like cells were encountered within the capsule and interfollicular septa. AChE reactivity was also found in dendritic-like cells localized in the cortical and cortico-medullary border. No changes in the density of perivascular noradrenergic innervation were noticeable during the ages studied, whereas the density of AChE-reactive fibres supplying vessels reached the adult pattern at 30 days, and then remained unvaried. The density of non-perivascular nerve fiber profiles, specially the AChE reactive type, increased until 30 days, remained unchanged until 75 days and then increased with aging (90-120 days). The interrelationship between the autonomic nervous system and the immune system is discussed
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