543 research outputs found
A statistical test spectrum: from robust to powerful
No full textThe concept of Scale Curve provides a graphical tool for analysis of multivariate data, with a broad range of statistical applications. Recent research in variants of Scale Curves have shown great promise, as they can be easily adapted to build robust non-parametric testing procedures under various scenarios, while preserving good power, and retaining the crucial virtues of easy computation and simple graphical representation.
This thesis investigates the properties of one such variant of Scale Curves, named the Determinant Scale Curve (dsc). It is shown that the dsc can be used to devise non-parametric exact tests for location of multivariate data with a special property (stated in next paragraph), under both one sample and multi-sample setups. Similar ideas are extended to tackle problems in linear regression, where the dsc is used to build tests for significance of the slope parameter.
For all the problems discussed, the dsc's actually provide a whole spectrum of tests. The tests at the rightmost end of the spectrum are shown to be Pitman equivalent to the benchmark most powerful tests for the given problem. As one moves towards the other end, the corresponding tests become progressively more and more robust, i.e. insensitive to outliers. Simulation results show that this robustification does not come with a serious loss of power under most situations.Ph.D.Includes bibliographical references (p. 61-63)by Somnath Mukherje
Synthesis and structural studies on di-oxovanadium(V) complexes of N(4)-substituted pyrazole based thiosemicarbazones
No full textAssessment of tropical cyclone amphan affected inundation areas using sentinel-1 satellite data
No full textTropical cyclones as natural disturbances, influence ecosystem structure, function and dynamics at the global scale. This study assesses the inundation due to the super cyclone Amphan in coastal districts of eastern India by leveraging the computational power of Google Earth Engine (GEE) and the availability of high resolution Sentinel-1 Synthetic Aperture Radar (SAR) data. A cloud-based image processing framework was developed and implemented in GEE for classification using Random Forest algorithm. The inundation areas due to storm surge owing to cyclone Amphan, were mapped and further categorised to different land use and land cover classes based on an existing land cover map. Sentinel-1 images were useful in post-cyclone studies for the change detection analysis due to its higher temporal resolution and cloud penetration ability. The study found that the majority of agricultural and agricultural fallow lands were inundated in the coastal districts. The availability of open-source cloud-based data processing platforms provides cost effective way to rapidly gather accurate geospatial information. Such information could be useful for emergency response planning and post-event disaster management including relief, rescue and rehabilitation measures; and crop yield loss assessment. Cyclone and Land Use and Land Cover (LULC) change can have significant impacts on the human population and if both coexist, the consequences for people and the surrounding environment may be severe
Exploring the neurotrophic effect of pleiotrophin on glial cells
Get PDFRecovery after stroke depends on the extent of neuronal regeneration and myelination of
existing and newly differentiated neurons. Regeneration process is governed by various factors
released from glial cells. During an injury, glial cells activate and form a glial scar surrounding the
lesion area. These activated glial cells produce and release various factors, including Chondroitin
sulfate proteoglycans (CSPGs), a component of the extra cellular matrix. CSPGs accumulate in
the glial scar and can modulate activity of adjacent cells including neurons, oligodendrocyte
precursor cells (OPCs), and microglia. CSPGs inhibit the growth of neurons and OPCs and inhibit
the differentiation of OPCs to oligodendrocytes. In this thesis, we examined how the neurotrophic
factor pleiotrophin (PTN) could counteract these inhibitory effects in neurons and glia. We first
tested the hypothesis that PTN can enhance the growth of neurons even in the presence of CSPGs.
Primary cortical neurons cultured on an inhibitory CSPGs matrix exhibited reduced neurite growth
relative to control conditions, but growth was restored with PTN treatment even in the presence of
the inhibitory matrix containing CSPGs. PTN induced a dose-dependent increase in neurite
outgrowth with optimum outgrowth at 15 ng mL-1 PTN (114.8% of neuronal outgrowth relative to
laminin control). The growth-promoting effect of PTN was blocked by inhibiting the activity of
anaplastic lymphoma kinase receptor (ALK) using 10 nM alectinib (ALK receptor antagonist)
(53.59 % of neuronal outgrowth relative to laminin control). Additionally, in the presence of
CSPGs, neurite outgrowth was also restored by activating signaling downstream of ALK via the
protein kinase B pathway (Akt pathway) using SC79 (an Akt activator), with optimum outgrowth
at 5 µM mL-1 PTN (78.43 % of neuronal outgrowth relative to laminin control). Thus, these data
suggest that PTN can restore the neurite outgrowth of neurons on the CSPGs matrix by activating
the protein kinase B pathway through ALK receptor.iii
Neurons with their axons myelinated by oligodendrocytes demonstrate improved signal
conduction efficiency, a crucial factor in the optimal functioning of the nervous system. Moreover,
microglia, as key players in the brain’s immune defense, play a pivotal role in supporting neurons
by monitoring for abnormalities, clearing debris, and contributing to the overall health and
homeostasis of the nervous system. During an injury, CSPGs in the glial scar greatly inhibit
differentiation of OPCs to oligodendrocytes and contribute to the activation of microglia. Here,
we found that PTN can modify the release of pro-inflammatory cytokines from microglia in the
presence of CSPGs. In the absence of inflammatory stimulation with IFN γ, PTN reduced the
expression of pro-inflammatory cytokines. In contrast, PTN potentiated the release of proinflammatory cytokines in the presence of inflammatory stimulus with IFN γ. Thus, the data
suggest that PTN can induce the differentiation of OPCs to oligodendrocytes, enhance the
inflammatory activity of microglia in the presence of IFN γ, and reduce pro-inflammatory
cytokines from microglia in the absence of an inflammatory stimulus.
Astrocytes exert a crucial influence on neurons by maintaining homeostasis, providing
metabolic support, and participating in synaptic regulation, contributing significantly to the overall
well-being and function of the nervous system. During an injury, activated astrocytes release
CSPGs to form the glial scar, but no study to date has measured the effect of PTN on astrocytes in
the presence of CSPGs in vitro. Our data suggest that PTN induces the release of pro-inflammatory
cytokines from astrocytes. To create an environment more closely approximating the in vivo
condition, also examined the effects of PTN on mixed glial cultures consisting of astrocytes,
microglia, and oligodendrocytes in the presence of CSPGs. We found that in the presence of
CSPGs, PTN reduced the expression of pro-inflammatory cytokines from mixed glia. In contrast,
the PTN showed a trend towards increased expression of pro-inflammatory cytokine during coiv
incubation with an inflammatory stimulus. Overall, our data indicates that PTN plays a pivotal role
in modulating the activity of neurons and glial cells in the presence of CSPGs, fostering an
environment that promotes the regeneration of neurons, the differentiation of oligodendrocytes,
and the reduction of neuroinflammation in a manner that is modulated by the inflammatory
activation of these cells. Thus, PTN holds the potential to be considered as a treatment therapy to
enhance the recovery process after brain injury
Diluted magnetic semiconductors of Zn-doped CeO2 nanoparticles synthesized by a chemical precursor method
No full textGraphitic carbon stabilized silver nanoparticles synthesized by a simple chemical precursor method
No full text
Can Patient-Centered Communication Reduce the Effects of Medical Mistrust on Patients\u27 Decision Making?
No full textObjective: Mistrust in medical institutions has been implicated as a barrier that disproportionately affects the quality of health care received by patients. Although patient-centered communication has been shown to improve patient-provider relationships, little is known as to whether it may reduce the effects of medical mistrust on patients’ decision-making and trust in physicians (physician mistrust). Method: In a laboratory study, 231 primary care patients (101 African American and 130 White participants) were randomly assigned to one of two conditions in which they viewed video recorded, standardized vignettes depicting a cardiologist recommending coronary bypass surgery to a patient diagnosed with angina and 3-vessel coronary artery disease. In each vignette, the cardiologist-actor demonstrated either low or high patient-centered communication behavior. Participants were asked to assume the role of the patient interacting with the video-recorded physician. Results: Hypotheses were partially supported. High levels of medical mistrust were associated with greater physician mistrust and lesser endorsement of the hypothetical bypass surgery. Among patients exposed to high patient-centered communication, the relationships between medical mistrust and both physician mistrust and surgery endorsement were weaker than among patients exposed to low patient-centered communication. Although African American patients reported greater medical mistrust compared with White patients, respondents’ race did not moderate the relationships. Conclusions: Results suggest that mistrust toward health care may unfavorably affect interactions and patients’ health-related outcomes. Physicians may buffer the effects of mistrust by using patient-centered communication skills such as soliciting the patient’s concerns and priorities and being responsive to the health care needs which patients identify. Author(s): Cuevas, Adolfo G.; O\u27Brien, Kerth; Saha, Somnath Source: HEALTH PSYCHOLOGY, 38 (4): 325-333 APR 2019 Document Type: Articl
Vibrational resonance in vibro-impact oscillator through fast harmonic excitation
Get PDFThis study focuses on extending the concept of weak signal enhancement from dynamical systems based on vibrational resonance of nonlinear systems, to non-smooth systems. A Van der Pol- Duffing oscillator with a one-sided barrier, subjected to harmonic excitations, has been considered an archetypical low-order model, whose response is weak. It is shown that the system response can be significantly enhanced by applying an additional harmonic excitation but with much higher frequencies. The reasons for the underlying physics are investigated analytically using multiple-scale analysis and the Blekham perturbation approach (direct partition motion). The analytical predictions are qualitatively validated using numerical simulations. This approach yields valuable insights into the intricate interplay between fast and slow excitations in non-smooth systems
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