Molecules for converting sunlight into electricity     

Ravi Mosurkal 《Resonance》2001,6(10):76-86

The dream of generating electricity from sunlight in large scale at low cost may not be that far from reality in this century. Rapidly emerging solar energy technology using low cost dye sensitized photovoltaic cells on plastics would be a real boost for the third world countries. Though the conventional silicon solar cells are efficient in converting solar energy into electricity until now, the non conventional solar cells based on molecular photosensitization by colored materials in wide band gap semiconductors is a fast growing field of basic scientific and industrial research. Present state-of-the-art cells using molecular dyes shows energy conversion efficiencies of 10–11%. In this article, we present the concept of dye-sensitized photovoltaic (DSPV) cell and the progress in current research. The important contributions of molecular dyes that are used as photosensitizers in these photovoltaic or solar cells are also described.  相似文献   

Revisiting Zhang’s scale of transactional distance: refinement and validation using structural equation modeling     

Ravi C. Paul  William Swart  Aixiu Monica Zhang  Kenneth R. MacLeod 《Distance Education》2015,36(3):364-382

Transactional distance has been defined as barriers to students’ engagement with learning in the online environment. This research updates Zhang’s (2003) scale of transactional distance, which quantified the extent of the barriers, in light of the massive changes in today’s web-based learning environment. The resulting revised scale of transactional distance (RSTD) is a parsimonious version with 12 elements (compared to 31 original) that measure the transactional distance between student and teacher, student and student, and student and content. The RSTD has excellent factorial validity and reliability, yields better fit statistics, and is easier and less time-consuming to apply. The transactional distance values are unique predictors of student satisfaction, which is correlated to learning and persistence (a major concern with massive open online courses). This information can form the basis for a systematic approach to improving the design of today’s contemporary open, flexible, distance education courses and thus serve as a valuable tool for researchers and educators alike.  相似文献   

Lipid peroxide levels and antioxidant status in alcoholic liver disease     

Seema Gupta  Rajesh Pandey  Ranjan Katyal  H. K. Aggarwal  R. P. Aggarwal  S. K. Aggarwal 《Indian journal of clinical biochemistry : IJCB》2005,20(1):67-71

The present study was conducted to evaluate some of the components of antioxidant defense system and oxidative damage in 20 male patients of alcoholic liver disease (ALD). The results were compared with 20 healthy male smokers and 20 healthy male non-smokers volunteers. Patients were subjected to detailed clinical examination and laboratory investigations. Blood samples were collected for estimating reduced glutathione (GSH), total thiols (T-SH) malondialdehyde (MDA), transaminases (AST, ALT), glutathione-S-transferease (GST) and gammaglutamyl transferase (GGT). Serum aspartate amino transferase (AST)/alanine amino transferase (ALT) ratio was significantly (p<0.01) reduced in ALD patients as compared to the controls. However, the core of utility of MDA and GST was found to be significantly (p<0.01) increased in ALD patients compared to controls. There was a significant negative correlation of MDA with both GSH and TSH. Plasma GGT levels were significantly (p<0.01) increased in alcoholics and the enzyme showed a significant positive correlation with MDA. These results give enough evidence of increased oxidative stress and compromised antioxidant defense system in patients with ALD.  相似文献   

The forgotten promise of e-government maturity: Assessing responsiveness in the digital public sector     

Kim Normann Andersen  Rony Medaglia  Ravi Vatrapu  Helle Zinner Henriksen  Robin GauldAuthor vitae 《Government Information Quarterly》2011,28(4):439-445

Assessing e-government responsiveness is one of the major gaps in the currently dominant e-government maturity models. While we have a relatively large pool of models focusing on technological and organizational integration from a supply side perspective, measures of responsiveness of e-government systems from a user perspective are still lacking. Replicating a study from New Zealand and Australia, this study explores the response time and quality of e-mail response in Danish local and central governments (N = 175). Despite that Denmark is high ranking in international benchmark studies, we find that one third of central government agencies did not respond at all, and close to 80% of the ministries provided none or incomplete answers. Local government responds faster and provides answers that are more complete and accurate than those provided by central government. Implications for e-government are discussed.  相似文献   

Comparative account of serum lipids,lipoproteins and apolipoprotein-B in patients of coronary artery disease     

Ritu Sharma  Mridula Mahajan  Ravi Kant 《Indian journal of clinical biochemistry : IJCB》2004,19(1):10-13

Serum total lipids (cholesterol and triglyceride), lipoproteins (VLDL, LDL and HDL) and Apolipoprotein-B levels of normal healthy individuals (n=25) and coronary artery disease patients (n=25) were estimated. The objective of the present study was to ascertain the role of apo-B in causation and inheritance of coronary artery disease. It was observed that on an average serum total cholesterol and triglyceride more than 200 mg/dl bring the individuals to a risk of coronary artery disease (CAD) irrespective of the age. CAD patients achieved this value at an early age (35–45 years). Similarly VLDL and LDL levels were found to be significantly raised in CAD patients when compared to that of age matched normal individuals, with patients achieving risk values at an early age. HDL levels were found to be significantly lower in CAD patients as compared to normal individuals. Serum apo-B levels were significantly raised in CAD patients as compared to age matched normal individuals. Patients with positive family history of CAD had raised serum apo-B levels than those having negative family history. A positive coefficient of correlation was observed between serum apo-B and LDL levels suggesting that more the number of Apo-B particles, more will be the synthesis of atherogenic particle (LDL). Patients with negative family history had serum apo-B levels closer to those of normal individuals and in these individuals HDL levels were found to be significantly lowered, suggesting that loss of scavenger role of HDL could be the risk factor responsible for the causation of CAD in these patients, with negative family history of coronary artery disease.  相似文献   

Self-Reporting and Test Discrepancy: Evidence from a National Literacy Survey in Bangladesh     

Samir Ranjan Nath 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》2007,38(3):119-133

This paper aims to explore the discrepancy between self-reported and test-based literacy estimates in Bangladesh. It uses the Education Watch national literacy survey data of 2002, during which the literacy status of a nationally representative sample was identified using the two methods referred to above. The findings revealed that the literacy rate generated through a literacy test was significantly lower than that found when the self-report method was used. The level of discrepancy varied from one population group to another, indicating that literacy assessment using the self-report method cannot be equally appropriate for all population groups. Those with a few years of schooling were at a particular risk of over-estimating their status. The paper makes a case for a written literacy assessment rather than an oral evaluation.  相似文献   

Self-Reporting and Test Discrepancy: Evidence from a National Literacy Survey in Bangladesh     

Samir Ranjan Nath 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》2007,53(2):119-133

This paper aims to explore the discrepancy between self-reported and test-based literacy estimates in Bangladesh. It uses the Education Watch national literacy survey data of 2002, during which the literacy status of a nationally representative sample was identified using the two methods referred to above. The findings revealed that the literacy rate generated through a literacy test was significantly lower than that found when the self-report method was used. The level of discrepancy varied from one population group to another, indicating that literacy assessment using the self-report method cannot be equally appropriate for all population groups. Those with a few years of schooling were at a particular risk of over-estimating their status. The paper makes a case for a written literacy assessment rather than an oral evaluation.  相似文献   

Lead toxicity as a result of herbal medication     

A. Ravi Raja  G. N. Vishal Babu  Geraldine Menezes  T. Venkatesh 《Indian journal of clinical biochemistry : IJCB》2008,23(2):200-203

Awareness about the toxic effects of non-essential metals is still lacking in developing countries. Lead is one among them, which ranks second in the Agency for Toxic Substances and Disease Registry’ s top 20 lists of toxic metals. Some of the herbal medicines prepared from certain roots and leaves are known to contain this toxic metal at alarming levels. We have a case of a person who suffered from the toxic effects of lead such as vomiting and colicky abdominal pain after consuming a herbal remedy for Jaundice treatment. This went unrecognized initially because of the presence of multiple problems like Malaria and Renal calculi. Lead poisoning as causative factor for anemia, vomiting and colic were confirmed only when blood lead concentration was estimated. A combination of chelation therapy and nutritional supplementation was found to be useful in reducing the body lead burden.  相似文献   

‘Racialised facilitative capital’ and the paving of differential paths to achievement of Afro-Trinidadian boys     

Ravi Rampersad 《British Journal of Sociology of Education》2014,35(1):73-93

Bourdieu describes capital as the political building blocks of social order that give meaning to social accumulation and consumption. Through a combination of Bourdieu’s sociology and critical race theory, this sojourn into Afro-Trinidadian boys’ achievement seeks to elucidate an approach to understanding capital as inherently raced. This is premised on an interrogation of Trinidadian society as pigmentocratically structured, where lightness is rewarded with a myriad of social advantages, and darkness denigrated as illegitimate and ‘other’. The premium placed on lighter skin is manifested interdependently in the forms of social, economic and cultural capital. As such, the operation of capital as politic not only reflects societal structures of power and domination, but importantly also contributes in the maintenance of said structures. The concept of ‘Racialised facilitative capital’ follows as inseparably both facilitator of social status and as racialised process.  相似文献   

Children’s access to pre‐school education in Bangladesh     

Samir Ranjan Nath  Kathy Sylva 《International Journal of Early Years Education》2007,15(3):275-295

Using the Education Watch household survey database, this paper explores children’s access to pre‐school education in Bangladesh. Participation in pre‐school education has been increasing in Bangladesh at the rate of 0.6% per year and the net enrolment rate was found to be 13.4% in 2005. Enrolment of over‐aged children in pre‐school education made the gross enrolment ratio as high as 30.5%. However, over half of the four to five year olds at school were actually enrolled in primary school and not in pre‐school. Moreover, 71% of the four‐ to five‐year group were out of school. Only a third of the four‐ to five‐year‐old children enrolled in schools had the opportunity to attend the English‐medium kindergartens or NGO‐run non‐formal schools, both of which provide better quality pre‐school education. Urban children, especially those with educated parents and from more privileged socio‐economic backgrounds, were more likely to have access to pre‐school education. The lack of a common pre‐school curriculum seems to have created further inequity among children at this very early age. An educational policy targeting poor and socially disadvantaged children with support from both the state and current pre‐school providers is urgently needed to provide four‐ to five‐year‐old children appropriate education for their needs.  相似文献