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Search Results: 1 - 10 of 304895 matches for " V. N. Tanya "
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Photonic Crystal Biosensor Based on Optical Surface Waves
Valery N. Konopsky,Tanya Karakouz,Elena V. Alieva,Chiara Vicario,Sergey K. Sekatskii,Giovanni Dietler
Sensors , 2013, DOI: 10.3390/s130202566
Abstract: A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately.
A Microbiological and Nutritional Evaluation of the West African Dried Meat Product, Kilishi
M. J. Jones, V. N. Tanya, C. M.F. Mbofung, D. N. Fonkem, D. E. Silverside
Journal of Food Technology in Africa , 2001,
Abstract: The quality attributes of Kilishi, a West African dried meat product were studied over an eight week storage period comparing traditional production and packaging systems with a potassium sorbate treatment system and simple modern packaging. Changes in chemical composition and microbiological counts are reported. Moisture and water activity results indicated that the experimental Kilishi was sufficiently dried to minimise microbial growth. Fat oxidation levels measured by free fatty acids (FFA) (%) on extracted fats were unacceptably high (>1.2-2.1%) and may be a reflection of the quality of the groundnut and its oil in the ingredients. Processing of beef into Kilishi appears to lead to a decrease in mineral availability. Results suggest that treatment of Kilishi with 10% (w/v) potassium sorbate confers a degree of protection of the product from mould contamination. Aflatoxin levels far exceeded all established safe limits and are thought to be due to the use of pre-contaminated groundnut, as mould growth levels in Kilishi were very low. The Journal of Food Technology in Africa Volume 6 No.4, 2001, pp. 126-129 KEY WORDS: aflatoxins, dried meat, food preservative, kilishi, potassium sorbate.
Risk of placental abruption in relation to migraines and headaches
Sixto E Sanchez, Michelle A Williams, Percy N Pacora, Cande V Ananth, Chungfang Qiu, Sheena K Aurora, Tanya K Sorensen
BMC Women's Health , 2010, DOI: 10.1186/1472-6874-10-30
Abstract: Cases were 375 women with pregnancies complicated by placental abruption, and controls were 368 women without an abruption. During in-person interviews conducted following delivery, women were asked if they had physician-diagnosed migraine, and they were asked questions that allowed headaches and migraine to be classified according to criteria established by the International Headache Society. Logistic regression procedures were used to calculate odds ratios (aOR) and 95% confidence intervals (CI) adjusted for confounders.Overall, a lifetime history of any headaches or migraine was associated with an increased odds of placental abruption (aOR = 1.60; 95% CI 1.16-2.20). A lifetime history of migraine was associated with a 2.14-fold increased odds of placental abruption (aOR = 2.14; 95% CI 1.22-3.75). The odds of placental abruption was 2.11 (95% CI 1.00-4.45) for migraineurs without aura; and 1.59 (95% 0.70-3.62) for migraineurs with aura. A lifetime history of tension-type headache was also increased with placental abruption (aOR = 1.61; 95% CI 1.01-2.57).This study adds placental abruption to a growing list of pregnancy complications associated with maternal headache/migraine disorders. Nevertheless, prospective cohort studies are needed to more rigorously evaluate the extent to which migraines and/or its treatments are associated with the occurrence of placental abruption.Placental abruption, the premature separation of the placenta before delivery of the fetus, complicates approximately 1% of all pregnancies [1-3]. Placental abruption is a significant cause of maternal and neonatal morbidity and infant mortality. Maternal complications include hemorrhagic shock, coagulopathy, disseminated intravascular coagulation, and renal failure. The condition is also associated with increased risks of preterm delivery and intrauterine growth restriction. Neonatal death and long term complications are also adverse outcomes following placental abruption [4,5]. Although placent
Structural equation modeling in medical research: a primer
Tanya N Beran, Claudio Violato
BMC Research Notes , 2010, DOI: 10.1186/1756-0500-3-267
Abstract: To facilitate its use we provide a series of steps for applying SEM to research problems. We then present three examples of how SEM has been utilized in medical and health sciences research.When many considerations are given to research planning, SEM can provide a new perspective on analyzing data and potential for advancing research in medical and health sciences.Structural equation modeling (SEM) is a powerful multivariate analysis technique that is widely used in the social sciences [1]. Its applications range from analysis of simple relationships between variables to complex analyses of measurement equivalence for first and higher-order constructs [2]. It provides a flexible framework for developing and analyzing complex relationships among multiple variables that allow researchers to test the validity of theory using empirical models. Perhaps its greatest advantage is the ability to manage measurement error, which is one of the greatest limitations of most studies. Although its application has been seen in many disciplines, it has yet to be extensively used in medical research and epidemiology.In a recent paper, we provided a "how to" for medical education researchers [3]. Specific principles and examples for the field of medical education were utilized. The purpose of the present paper, however, is to introduce structural equation modeling through explanation and demonstration of its methods in an attempt to disseminate it more widely in medical and health sciences research.The use of SEM has now become widespread across research domains. In psychology, for example, the citation frequency of SEM has steadily increased from 164 in 1994 to 343 in 2000 and then to 742 in the last year (based on the citation frequency of SEM and M[ANOVA] of PsychINFO database 1970-2010) [4,5]. This suggests that researchers recognize its application to a variety of research questions, types of data, and methods of study. An increase in use of sophisticated tools of analysis reflec
A full vectorial model for pulse propagation in emerging waveguides with subwavelength structures part I: Kerr nonlinearity
Shahraam Afshar V.,Tanya M. Monro
Physics , 2008,
Abstract: The propagation of pulses through waveguides with subwavelength features, inhomogeneous transverse structure, and high index contrast cannot be described accurately using existing models in the presence of nonlinear effects. Here we report the development of a generalised full vectorial model of nonlinear pulse propagation and demonstrate that, unlike the standard pulse propagation formulation, the z-component of guided modes plays a key role for these new structures, and results in generalised definitions of the nonlinear coefficient $\gamma,$ $A_{eff}$, and mode orthognality. While new definitions reduce to standard definitions in some limits, significant differences are predicted, including a factor of $\sim2$ higher value for $\gamma$, for emerging waveguides and microstructured fibers.
Control of CydB and GltA1 Expression by the SenX3 RegX3 Two Component Regulatory System of Mycobacterium tuberculosis
Gretta Roberts,Indumathi S. Vadrevu,Murty V. Madiraju,Tanya Parish
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021090
Abstract: Two component regulatory systems are used widely by bacteria to coordinate changes in global gene expression profiles in response to environmental signals. The SenX3-RegX3 two component system of Mycobacterium tuberculosis has previously been shown to play a role in virulence and phosphate-responsive control of gene expression. We demonstrate that expression of SenX3-RegX3 is controlled in response to growth conditions, although the absolute changes are small. Global gene expression profiling of a RegX3 deletion strain and wild-type strain in different culture conditions (static, microaerobic, anaerobic), as well as in an over-expressing strain identified a number of genes with changed expression patterns. Among those were genes previously identified as differentially regulated in aerobic culture, including ald (encoding alanine dehydrogenase) cyd,encoding a subunit of the cytochrome D ubiquinol oxidase, and gltA1, encoding a citrate synthase. Promoter activity in the upstream regions of both cydB and gltA1 was altered in the RegX3 deletion strain. DNA-binding assays confirmed that RegX3 binds to the promoter regions of ald, cydB and gltA1 in a phosphorylation-dependent manner. Taken together these data suggest a direct role for the SenX-RegX3 system in modulating expression of aerobic respiration, in addition to its role during phosphate limitation.
Catalase enzyme in mitochondria of Saccharomyces cerevisiae
Petrova,Ventsislava Yankova; Rasheva,Tanya Vassileva; Kujumdzieva,Anna V.;
Electronic Journal of Biotechnology , 2002,
Abstract: catalase and superoxide dismutase activities have been explored in the yeast saccharomyces cerevisiae during batchwise growth experiment. during the diauxic growth in ypd medium high ys values were obtained (0.415 - 0.423) and correlation between the total activities of both enzymes has been found. a mitochondrial fraction from three type strains of saccharomyces cerevisiae has been isolated. the purity of this fraction was proved through different enzyme assays: hexokinase, glucose-6-phosphate dehydrogenase, d-amino acid oxidase, isocitric lyase, succinate dehydrogenase. then the catalase, peroxidase, mn and cu/zn superoxide dismutase activities were evaluated in the mitochondrial fraction. polyacrylamide gel electrophoresis separations allowed to identify a mitochondrial catalase as a band of 0.239 rm value. it differed from the two catalase specific bands with rm values 0.218 and 0.257 obtained from the crude extract. it was proved that the three catalase proteins are charge isomers. a positive correlation between the activity of mitochondrial catalase and mn superoxide dismutase also takes place. molecular weight of mitochonrial catalase protein has been determined as 240 kd.
Abundance and stratification analysis of the CP star HD 103498
Chhavi P. Pandey,Denis V. Shulyak,Tanya Ryabchikova,Oleg Kochukhov
Physics , 2011, DOI: 10.1111/j.1365-2966.2011.19281.x
Abstract: Slow rotation and absence of strong mixing processes in atmospheres of chemically peculiar stars develop ideal conditions for the appearance of abundance anomalies through the mechanism of microscopic particle diffusion. This makes these objects look spectroscopically and photometrically different from their "normal" analogs. As a result, it is often difficult to accurately determine atmospheric parameters of these stars and special methods are needed for the consistent analysis of their atmospheres. The main aim of the present paper is to analyse atmospheric abundance and stratification of chemical elements in the atmosphere of the chemically peculiar star HD 103498. We find that two model atmospheres computed with individual and stratified abundances provide reasonable fit to observed spectroscopic and photometric indicators: Teff=9300 K, logg=3.5 and Teff=9500K, logg=3.6. It is shown that Mg has a large abundance gradient in the star's atmosphere with accumulation of Mg ions in the uppermost atmospheric layers, whereas Si demonstrates opposite behaviour with accumulation in deep layers. In addition, a detailed non-LTE analysis showed that none of Mg transitions under consideration is a subject of noticeable non-LTE effects. Comparing observed photometry transformed to physical units we estimated the radius of HD 103498 to be between R=(4.56 +/- 0.77)Rsun for Teff=9300K, logg=3.5 and R=(4.39 +/- 0.75)Rsun for Teff=9500K, logg=3.6 models respectively. We note that the lack of suitable observations in absolute units prevents us to uniquely determine the Teff of the star at the current stage of analysis.
Molecular markers and their applications in fisheries and aquaculture  [PDF]
Tanya Chauhan, Kumar Rajiv
Advances in Bioscience and Biotechnology (ABB) , 2010, DOI: 10.4236/abb.2010.14037
Abstract: Genetic variation in a species enhances the capability of organism to adapt to changing environment and is necessary for survival of the species. Genetic variation arises between individuals leading to differentiation at the level of population, species and higher order taxonomic groups. The genetic diversity data has varied application in research on evolution, conservation and management of natural resources and genetic improvement programmes, etc. Development of Molecular genetic markers has powerful ability to detect genetic studies of individuals, populations or species. These molecular markers combined with new statistical developments have revolutionized the analytical power, necessary to explore the genetic diversity. Molecular markers and their statistical analysis revolutionized the analytical power, necessary to explore the genetic diversity. Various molecular markers, protein or DNA (mt-DNA or nuclear DNA such as microsatellites, SNP or RAPD) are now being used in fisheries and aquaculture. These markers provide various scientific observations which have importance in aquaculture practice recently such as: 1) Species Identification 2) Genetic variation and population structure study in natural populations 3) Comparison between wild and hatchery populations 4) Assessment of demographic bottleneck in natural population 5) Propagation assisted rehabilitation programmes. In this review article, we have concentrated on the basics of molecular genetics, overview of commonly used markers and their application along with their limitations (major classes of markers) in fisheries and aquaculture studies.
Family History of Cancer and Smoking Cessation, Is There a Role for Physicians?  [PDF]
Wenbin Liang, Tanya Chikritzhs
International Journal of Clinical Medicine (IJCM) , 2012, DOI: 10.4236/ijcm.2012.31002
Abstract: Aim: This study aims to investigate the relationships among family history of cancer, physician’s advice on quitting, and motivation to quit among smokers in the United State. Method: This study using data collected by the 2010 National Health Interview Survey. Five separate sets of multivariate logistic regression models were used to investigate the three-direction relationships among: 1) effect of family cancer history on medical doctors’ advice on quitting, 2) effect of family cancer history on motivation to quit smoking, 3) effect of doctor’s advice on smokers’ motivation to quit. Results: Smoking cessation advice given by physicians has a significant effect on both smoker’s motivation and action taken to quit smoking, but a large proportion of the smokers with family cancer history did not receive doctor’s advice on quitting. Conclusion: Family history of lung cancer or other cancer types was not found to be associated with increased motivation to quit smoking. This is at least partly due to poor collection of family cancer history by physicians. This may be ameliorated by promoting the use of a recently developed self-administered tool for the collection of patient data on family cancer history in primary care settings.
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