207 research outputs found
Interference of stochastic resonances: Splitting of Kramers' rate
We consider the escape of particles located in the middle well of a symmetric
triple well potential driven sinusoidally by two forces such that the potential
wells roll as in stochastic resonance and the height of the potential barrier
oscillates symmetrically about a mean as in resonant activation. It has been
shown that depending on their phase difference the application of these two
synchronized signals may lead to a splitting of time averaged Kramers' escape
rate and a preferential product distribution in a parallel chemical reaction in
the steady state
Assessing noninferiority in a three-arm trial using the Bayesian Approach
Non-inferiority trials, which aim to demonstrate that a test product is not worse than a competitor by more than a pre-specified small amount, are of great importance to the pharmaceutical community. As a result, methodology for designing and analyzing such trials is required, and developing new methods for such analysis is an important area of statistical research. The three-arm clinical trial is usually recommended for non-inferiority trials by the Food and Drug Administration (FDA). The three-arm trial consists of a placebo, a reference, and an experimental treatment, and simultaneously tests the superiority of the reference over the placebo along with comparing this reference to an experimental treatment. In this paper, we consider the analysis of noninferiority trials using Bayesian methods which incorporate both parametric as well as semi-parametric models. The resulting testing approach is both flexible and robust. The benefit of the proposed Bayesian methods is assessed via simulation, based on a study examining Home Based Blood Pressure Interventions
The effect of comorbidities of preeclampsia and eclampsia on maternal and fetal outcome
Background: The aim of this study is to comparatively assess the maternal and fetal outcome in preeclampsia and eclampsia patients with and without comorbidities. The objectives are to assess the comorbidities associated with preeclampsia and eclampsia cases and to find out the effects of the comorbidities of preeclampsia and eclampsia on maternal and fetal outcome.
Methods:380 patients who had attended antenatal OPD and emergency labour room of Assam medical college and hospital, Dibrugarh during June 2020 to July 2021 with preeclampsia and eclampsia were selected for present study. Based on relevant history, clinical and laboratory findings, these patients were further evaluated for associated comorbidities. The cases were distributed in the respective comorbidity group. Then the outcome of the mother and the baby were analyzed till the day of discharge in patients without comorbidities and with comorbidities and the same was compared.
Results: The eventful maternal (44.1%) and fetal (50.92%) outcome was more in preeclampsia and eclampsia patients with comorbidities than in patients without comorbidities which is statistically significant, (p value=0.029), (p value=0.009) respectively.
Conclusions: The effect of preeclampsia and eclampsia itself would adversely affect the pregnancy outcome and the effect is worse when associated with comorbidities. Appropriate prenatal counselling and optimization of the comorbidities is critical for women who are planning pregnancy
Control of NFAT Isoform Activation and NFAT-Dependent Gene Expression through Two Coincident and Spatially Segregated Intracellular Ca 2+ Signals
© 2016 The Author(s) Excitation-transcription coupling, linking stimulation at the cell surface to changes in nuclear gene expression, is conserved throughout eukaryotes. How closely related coexpressed transcription factors are differentially activated remains unclear. Here, we show that two Ca2+-dependent transcription factor isoforms, NFAT1 and NFAT4, require distinct sub-cellular InsP3 and Ca2+ signals for physiologically sustained activation. NFAT1 is stimulated by sub-plasmalemmal Ca2+ microdomains, whereas NFAT4 additionally requires Ca2+ mobilization from the inner nuclear envelope by nuclear InsP3 receptors. NFAT1 is rephosphorylated (deactivated) more slowly than NFAT4 in both cytoplasm and nucleus, enabling a more prolonged activation phase. Oscillations in cytoplasmic Ca2+, long considered the physiological form of Ca2+ signaling, play no role in activating either NFAT protein. Instead, effective sustained physiological activation of NFAT4 is tightly linked to oscillations in nuclear Ca2+. Our results show how gene expression can be controlled by coincident yet geographically distinct Ca2+ signals, generated by a freely diffusible InsP3 message
Kinetics of self-induced aggregation of Brownian particles: non-Markovian and non-Gaussian features
In this paper we have studied a model for self-induced aggregation in
Brownian particle incorporating the non-Markovian and non-Gaussian character of
the associated random noise process. In this model the time evolution of each
individual is guided by an over-damped Langevin equation of motion with a
non-local drift resulting from the local unbalance distributions of the other
individuals. Our simulation result shows that colored nose can induce the
cluster formation even at large noise strength. Another observation is that
critical noise strength grows very rapidly with increase of noise correlation
time for Gaussian noise than non Gaussian one. However, at long time limit the
cluster number in aggregation process decreases with time following a power
law. The exponent in the power law increases remarkable for switching from
Markovian to non Markovian noise process
Modeling of normal force and finishing torque considering shearing and ploughing effects in ultrasonic assisted magnetic abrasive finishing process with sintered magnetic abrasive powder
Ultrasonic assisted magnetic abrasive finishing process (UAMAF) is a precision manufacturing process that results
nano-scale level finish in a part. Normal force on a particle helps indenting the particle in the work surface
whereas horizontal force provides finishing torque that in-turn helps the particle to perform micro-machining.
Better understanding of the effect of these forces on material removal and wear pattern of the work-piece necessitates mathematical modeling of normal force and finishing torque and subsequently its validation with
experimental results. In the present study, single particle interaction concept is considered to develop a model which is subsequently applied for all active particles of magnetic abrasive powder (MAP). Separation point theory is applied to consider the effect of ploughing below a critical depth and shearing above that depth. Normal components of shearing and ploughing forces are considered for calculating normal force and horizontal
components of shearing and ploughing forces are taken to calculate finishing torque. Johnson-Cook model is applied to calculate shearing strength of the work material during UAMAF. The impact of ultrasonic vibrations is considered while calculating strain rate. Images are taken with the help of scanned electron microscope and atomic force microscope to study the material removal and wear mechanism during UAMAF process. Predicted values of force and torque model are validated with the experimental values
Langevin dynamics with dichotomous noise; direct simulation and applications
We consider the motion of a Brownian particle moving in a potential field and
driven by dichotomous noise with exponential correlation. Traditionally, the
analytic as well as the numerical treatments of the problem, in general, rely
on Fokker-Planck description. We present a method for direct numerical
simulation of dichotomous noise to solve the Langevin equation. The method is
applied to calculate nonequilibrium fluctuation induced current in a symmetric
periodic potential using asymmetric dichotomous noise and compared to
Fokker-Planck-Master equation based algorithm for a range of parameter values.
Our second application concerns the study of resonant activation over a
fluctuating barrier.Comment: Accepted in Journal of Statistical Mechanics: Theory and Experimen
Non-Hermitian quantum mechanics in non-commutative space
We study non Hermitian quantum systems in noncommutative space as well as a
\cal{PT}-symmetric deformation of this space. Specifically, a
\mathcal{PT}-symmetric harmonic oscillator together with iC(x_1+x_2)
interaction is discussed in this space and solutions are obtained. It is shown
that in the \cal{PT} deformed noncommutative space the Hamiltonian may or may
not possess real eigenvalues depending on the choice of the noncommutative
parameters. However, it is shown that in standard noncommutative space, the
iC(x_1+x_2) interaction generates only real eigenvalues despite the fact that
the Hamiltonian is not \mathcal{PT}-symmetric. A complex interacting
anisotropic oscillator system has also been discussed.Comment: 5 pages, revised versio
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