Note On Linear Stability of Steady Hydromagetic Flows of An Incompressible Fluid

In the present paper energy method is used to obtain two sufficient conditions for linear stability of steady hydrodynamical flows. The idea of the method is to construct a small three-dimensional perturbations and formulate the stability criteria for the steady magnetohydrodynamic flows of an ideal incompressible.The stability conditions so obtained ensure non existence of perturbations which grow with time faster than linealy

Early adversity in rural India impacts the brain networks underlying visual working memory

There is a growing need to understand the global impact of poverty on early brain and behavioural development, particularly with regard to key cognitive processes that emerge in early development. Although the impact of adversity on brain development can trap children in an intergenerational cycle of poverty, the massive potential for brain plasticity is also a source of hope: reliable, accessible, culturally-agnostic methods to assess early brain development in low resource settings might be used to measure the impact of early adversity, identify infants for timely intervention, and guide the development and monitor the effectiveness of early interventions. Visual working memory (VWM) is an early marker of cognitive capacity that has been assessed reliably in early infancy and is predictive of later academic achievement in Western countries. Here, we localized the functional brain networks that underlie VWM in early development in rural India using a portable neuroimaging system, and we assessed the impact of adversity on these brain networks. We recorded functional brain activity as young children aged 18-207 weeks performed a visual working memory task. Brain imaging results revealed localized activation in the frontal cortex, replicating findings from a midwestern US sample. Critically, children from families with low maternal education and income showed weaker brain activity and poorer distractor suppression in canonical working memory areas in the left frontal cortex. Implications of this work are far-reaching: it is now cost-effective to localize functional brain networks in early development in low-resource settings, paving the way for novel intervention and assessment methods

A Note On Linear Stability of Steady Hydromagetic Flows of An Incompressible Fluid

ABSTRACT In the present paper energy method is used to obtain two sufficient conditions for linear stability of steady hydrodynamical flows. The idea of the method is to construct a small three-dimensional perturbations and formulate the stability criteria for the steady magnetohydrodynamic flows of an ideal incompressible.The stability conditions so obtained ensure non existence of perturbations which grow with time faster than linealy

Electrochemical oxidation of CO on Cu single crystals under alkaline conditions

We perform a joint experimental-theoretical study of the electrochemical oxidation of CO on copper (Cu) under alkaline conditions. Using cyclic voltammetry on Cu single crystal surfaces, we demonstrate that both Cu terraces and steps show CO oxidation activity at potentials just slightly positive (0.03-0.14 V) of the thermodynamic equilibrium potential. The overpotentials are 0.23-0.12 V lower than that of gold (approx. 0.26 V), which up until now has been considered to be the most active catalyst for this process. Our theoretical calculations suggest that Cu's activity arises from the advantageous combination of simultaneous *OH adsorption under CO oxidation potentials and surmountable *CO-*OH coupling barriers. Experimentally observed onset potentials are in agreement with the computed onsets of *OH adsorption. We furthermore show that the onsets of *OH adsorption on steps are more affected by *CO-*OH interactions than on terraces due to a stronger competitive adsorption. Overall, Cu(100) shows the lowest overpotential (0.03 V) of the facets considered.Comment: 16 pages, 3 figures plus supplementary informatio

Comparison of polymeric stabilization of organic/inorganic (MEH-PPV/TiO2) hybrid composites synthesized via different routes

For colloidally stable nanoparticle dispersions, it is imperative that some sort of interparticle repulsion is introduced to balance or overcome the ever-present van der Waals forces of attraction. In the present work, we have demonstrated that an efficient stabilization of a TiO2 nanoparticle dispersion depends upon the pH and zeta potential which are influenced by the route of synthesis (aqueous or ethanol based) and by the addition of suitable polymeric dispersants. In this work, both pH and zeta potential of the TiO2 nanoparticles have been accredited as a good index of the magnitude of the interaction between colloidal particles and their measurements are used to assess the stability of TiO2 and polymer/TiO2 composite colloidal systems synthesized via different routes. The concept of steric and electrostatic stabilization of colloids for both TiO2 (aqueous) and TiO2 (ethanol) systems and its corresponding polymer nanocomposites has been explained appropriately by means of a pictorial model. The efficient charge transfer across the polymer-TiO2(aqueous) interface as inferred from photoluminescence quenching measurements meets the desired criteria for the selection of TiO2(aqueous) materials for hybrid organic photovoltaic devices

Determining the accuracy of elastography in differentiating benign from malignant nodules with fine needle aspiration cytology/ histopathological examination as the gold standard

Background: Thyroid nodules are very common and are found in 4% to 8% of adults by palpation, 41% by ultrasound, particularly among iodine-deficient individuals. Most nodules are benign, with less than 5% of them being malignant. Aims and Objectives: To determine the accuracy of elastography in differentiating benign from malignant nodules with Fine Needle Aspiration Cytology/ Histopathological examination as the gold standard. To determine the strain ratio of benign and malignant thyroid nodules. Material and Methods: The study was done at the Batra hospital & medical research centre (BMHRC), New Delhi. In this study 37 patients of thyroid swelling with total 43 nodules were evaluated finally during the study period. A prospective observational study of patient population who undergo grey-scale ultrasound (US) and real time ultrasound elastography (USE) for thyroid nodules and subsequently go for fine needle aspiration cytology/ histopathological examination for same. Results: The study comprises of 37 patients having 43 thyroid nodules. All patients underwent gray scale USG and ultrasound elastography followed by FNAC/histopathology examination. Conclusion: This prospective observational study shows that ultrasound elastography is a promising imaging technique and that in expert hands, it is a useful complement to US, enhancing its accuracy for thyroid malignancy detection and risk stratification. Elastography may be used to guide the follow up of lesions negative for malignancy at cytology or histopathology. Given the high prevalence of thyroid nodules and the substantial costs related to their workup and management, the use of USE could be a valuable tool for a better selection of nodules that need cytological evaluation. Large multicenter studies and periodic evaluation by international experts consensus panels are necessary to establish the role of USE in the diagnostic workup of thyroid nodules