Diffusion of a chemically reactive species of a power-law fluid past a stretching surface

A numerical solution for the steady magnetohydrodynamic (MHD) non-Newtonian power-law fluid flow over a continuously moving surface with species concentration and chemical reaction has been obtained. The viscous flow is driven solely by the linearly stretching sheet, and the reactive species emitted from this sheet undergoes an isothermal and homogeneous one-stage reaction as it diffuses into the surrounding fluid. Using a similarity transformation, the governing non-linear partial differential equations are transformed into coupled nonlinear ordinary differential equations. The governing equations of the mathematical model show that the flow and mass transfer characteristics depend on six parameters, namely, the power-law index, the magnetic parameter, the local Grashof number with respect to species diffusion, the modified Schmidt number, the reaction rate parameter, and the wall concentration parameter. Numerical solutions for these coupled equations are obtained by the KellerBox method, and the solutions obtained are presented through graphs and tables. The numerical results obtained reveal that the magnetic field significantly increases the magnitude of the skin friction, but slightly reduces the mass transfer rate. However, the surface mass transfer strongly depends on the modified Schmidt number and the reaction rate parameter; it increases with increasing values of these parameters. The results obtained reveal many interesting behaviors that warrant further study of the equations related to non-Newtonian fluid phenomena, especially shear-thinning phenomena. Shear thinning reduces the wall shear stress. © 2011 Elsevier Ltd. All rights reserved

Neonatal exposure to 17β-estradiol down-regulates the expression of synaptogenesis related genes in selected brain regions of adult female rats

Aims Administration of estradiol or compounds with estrogenic activity to newborn female rats results in irreversible masculinization as well as defeminization in the brain and the animals exhibit altered reproductive behavior as adults. The cellular and molecular mechanism involved in inducing the irreversible changes is largely unknown. In the present study, we have monitored the changes in the expression of selected synaptogenesis related genes in the sexually dimorphic brain regions such as POA, hypothalamus and pituitary following 17β-estradiol administration to neonatal female rats. Main methods Female Wistar rats which were administered 17β-estradiol on day 2 and 3 after birth were sacrificed 120 days later and the expression levels of genes implicated in synaptogenesis were monitored by semi-quantitative reverse transcription PCR. Since estradiol induced up-regulation of COX-2 in POA is a marker for estradiol induced masculinization as well as defeminization, in the present study only animals in which the increase in expression of COX-2 gene was observed in POA were included in the study. Key findings Down-regulation of genes such as NMDA-2B, NETRIN-1, BDNF, MT-5 MMP and TNF-α was observed in the pre-optic area of neonatally E2 treated female rat brain but not in hypothalamus and pituitary compared to the vehicle- treated controls as assessed by RT-PCR and Western blot analysis. Significance Our results suggest a possibility that down-regulation of genes associated with synaptogenesis in POA, may be resulting in disruption of the cyclical regulation of hormone secretion by pituitary the consequence of which could be infertility and altered reproductive behavior

Ferroelectric Properties and Transmission Response ofPZN-PT Single Crystals for Underwater Communication

Single crystal of Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 (PZN-PT) at the composition of morphotropicphase boundary (MPB) shows a very high electromechanical coupling coefficient, piezoelectriccoefficient, and dielectric constant compared to conventional PZT ceramics. These exceptionalproperties of these single crystals find enormous applications in medical ultrasound imaging andunderwater communication (Sonar). The growth of PZN-PT single crystals has been carried outby bottom-supported flux Bridgman method. There are many growth issues to be addressedduring the process of growth. The grown crystals are oriented and cut along <001> directionwith the crystal dimension of 8 x 6 x 1.5 mm3 for further analysis. The oriented crystals were poledat a rate of 1 kV/mm. The poled crystals have been characterised for dielectric, strain andpiezoelectric values. Further, the poled specimen were tested for transmitting response at variousfrequencies in acoustic test facility and the difficulties in their growth

Energy poverty, institutional reform and challenges of sustainable development: the case of India

This paper assesses recent efforts by the Indian Government to tackle energy poverty and sustainable development. It focuses on the new integrated energy policy, and initiatives to disseminate improved cookstoves and develop energy alternatives for transport. The success of government initiatives in cleaner biomass cookstoves and village electrification has historically been limited, and institutional reforms in the 2000s promoted market-led and ‘user-centred’ approaches, and encouraged biofuels as a ‘pro-poor’ route to rural development and energy security. The paper argues that such interventions have reopened tensions and conflicts around land-use, intra-community inequalities and the role of corporate agendas in sustainable energy

Motivational Social Visualizations for Personalized E-Learning

A large number of educational resources is now available on the Web to support both regular classroom learning and online learning. However, the abundance of available content produces at least two problems: how to help students find the most appropriate resources, and how to engage them into using these resources and benefiting from them. Personalized and social learning have been suggested as potential methods for addressing these problems. Our work presented in this paper attempts to combine the ideas of personalized and social learning. We introduce Progressor + , an innovative Web-based interface that helps students find the most relevant resources in a large collection of self-assessment questions and programming examples. We also present the results of a classroom study of the Progressor +  in an undergraduate class. The data revealed the motivational impact of the personalized social guidance provided by the system in the target context. The interface encouraged students to explore more educational resources and motivated them to do some work ahead of the course schedule. The increase in diversity of explored content resulted in improving students’ problem solving success. A deeper analysis of the social guidance mechanism revealed that it is based on the leading behavior of the strong students, who discovered the most relevant resources and created trails for weaker students to follow. The study results also demonstrate that students were more engaged with the system: they spent more time in working with self-assessment questions and annotated examples, attempted more questions, and achieved higher success rates in answering them

Collecting the data but missing the point: Validity of hand hygiene audit data

Background: Monitoring of hand hygiene compliance (HHC) by observation has been used in healthcare for more than a decade to provide assurance of infection control practice. The validity of this information is rarely tested. Aim: To examine the process and validity of collecting and reporting HHC data based on direct observation of compliance. Methods: Five years of HHC data routinely collected in one large National Health Service hospital trust were examined. The data collection process was reviewed by survey and interview of the auditors. HHC data collected for other research purposes undertaken during this period were compared with the organizational data set. Findings: After an initial increase, the reported HHC remained unchanged close to its intended target throughout this period. Examination of the data collection process revealed changes, including local interpretations of the data collection system, which invalidated the results. A minority of auditors had received formal training in observation and feedback of results. Conclusion: Whereas observation of HHC is the current gold standard, unless data collection definitions and methods are unambiguous, published, carefully supervised, and regularly monitored, variations may occur which affect the validity of the data. If the purpose of HHC monitoring is to improve practice and minimize transmission of infection, then a focus on progressively improving performance rather than on achieving a target may offer greater opportunities to achieve this

Initial feasibility and challenges of hyperpolarized 129Xe MRI in neonates with bronchopulmonary dysplasia

Purpose The underlying functional and microstructural lung disease in neonates who are born preterm (bronchopulmonary dysplasia, BPD) remains poorly characterized. Moreover, there is a lack of suitable techniques to reliably assess lung function in this population. Here, we report our preliminary experience with hyperpolarized 129Xe MRI in neonates with BPD. Methods Neonatal intensive care patients with established BPD were recruited (N = 9) and imaged at a corrected gestational age of median:40.7 (range:37.1, 44.4) wk using a 1.5T neonatal scanner. 2D 129Xe ventilation and diffusion-weighted images and dissolved phase spectroscopy were acquired, alongside 1H 3D radial UTE. 129Xe images were acquired during a series of short apneic breath-holds (˜3 s). 1H UTE images were acquired during tidal breathing. Ventilation defects were manually identified and qualitatively compared to lung structures on UTE. ADCs were calculated on a voxel-wise basis. The signal ratio of the 129Xe red blood cell (RBC) and tissue membrane (M) resonances from spectroscopy was determined. Results Spiral-based 129Xe ventilation imaging showed good image quality and sufficient sensitivity to detect mild ventilation abnormalities in patients with BPD. 129Xe ADC values were elevated above that expected given healthy data in older children and adults (median:0.046 [range:0.041, 0.064] cm2s−1); the highest value obtained from an extremely pre-term patient. 129Xe spectroscopy revealed a low RBC/M ratio (0.14 [0.06, 0.21]). Conclusion We have demonstrated initial feasibility of 129Xe lung MRI in neonates. With further data, the technique may help guide management of infant lung diseases in the neonatal period and beyond