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Search Results: 1 - 10 of 640 matches for " Shetty Omkar "
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Efficacy of casein phosphopeptide-amorphous calcium phosphate to prevent stain absorption on freshly bleached enamel: An in vitro study
Singh Raghuwar,Ram Sabita,Shetty Omkar,Chand Pooran
Journal of Conservative Dentistry , 2010,
Abstract: Background: Teeth when subjected to bleaching bring about the desiccation of the enamel, making it more susceptible to stain absorption. While subjecting the freshly bleached enamel surface to various surface treatments of Fluoride and Casein Phosphopeptide - Amorphous Calcium phosphate (CPP-ACP) brought about the reduction in stain absorption, which is assessed in this study. Aims: The study aims to evaluate the tea stain absorption on freshly bleached enamel surface of extracted human teeth with varied surface treatment. The stain absorption was evaluated at the end of one hour and 24 hours post bleaching. Materials and Methods: Forty extracted human permanent maxillary central incisors were subjected to bleaching with 10% carbamide peroxide for eight days. They were divided into four groups of 10 each. Group I was control group. Group II was immersed in tea solution without surface treatment, while Group III and IV were immersed in tea solution with surface treatment of topical Fluoride and CPP-ACP respectively. Spectrophotometer was used for color analysis. Results: Surface treatment with CPP-ACP and topical fluoride on freshly beached enamel surface, significantly reduced the stain absorption. Conclusion: Remineralizing agents reduce stain absorption after tooth bleaching.
An empirical Bayes mixture method for effect size and false discovery rate estimation
Omkar Muralidharan
Statistics , 2010, DOI: 10.1214/09-AOAS276
Abstract: Many statistical problems involve data from thousands of parallel cases. Each case has some associated effect size, and most cases will have no effect. It is often important to estimate the effect size and the local or tail-area false discovery rate for each case. Most current methods do this separately, and most are designed for normal data. This paper uses an empirical Bayes mixture model approach to estimate both quantities together for exponential family data. The proposed method yields simple, interpretable models that can still be used nonparametrically. It can also estimate an empirical null and incorporate it fully into the model. The method outperforms existing effect size and false discovery rate estimation procedures in normal data simulations; it nearly acheives the Bayes error for effect size estimation. The method is implemented in an R package (mixfdr), freely available from CRAN.
Slow and fast development in ladybirds: occurrence, effects and significance
G. Mishra,Omkar
Web Ecology (WE) , 2012, DOI: 10.5194/we-12-19-2012
Abstract: Developmental and growth rates are known to vary in response to genetic, developmental, physiological and environmental factors. However, developmental variations that exist within a cohort under any constant rearing condition are not so well investigated. A few such prominent polymorphisms have been studied, but not the subtle ones. The current study investigates the presence of such varying rates of development, slow and fast, in a cohort reared under constant conditions in two ladybirds, Cheilomenes sexmaculata and Propylea dissecta. Our results reveal slow and fast developers in the cohorts of each species and the ratio of slow and fast developers was similar. Slow developers showed a female biased sex ratio. The two developmental variants differed significantly in juvenile duration only in the first instar and the pupal stage, though variations in developmental time were observed in all stages. Fecundity was higher in slow developers, but developmental rates did not affect egg viability. The similar ratio in both ladybirds indicates it to be a result of either presence of a constant ratio across species or an effect of the similar rearing environment.
On epsilon-optimality of the pursuit learning algorithm
Ryan Martin,Omkar Tilak
Computer Science , 2011, DOI: 10.1239/jap/1346955334
Abstract: Estimator algorithms in learning automata are useful tools for adaptive, real-time optimization in computer science and engineering applications. This paper investigates theoretical convergence properties for a special case of estimator algorithms: the pursuit learning algorithm. In this note, we identify and fill a gap in existing proofs of probabilistic convergence for pursuit learning. It is tradition to take the pursuit learning tuning parameter to be fixed in practical applications, but our proof sheds light on the importance of a vanishing sequence of tuning parameters in a theoretical convergence analysis.
Second Order Calibration: A Simple Way to Get Approximate Posteriors
Omkar Muralidharan,Amir Najmi
Statistics , 2015,
Abstract: Many large-scale machine learning problems involve estimating an unknown parameter $\theta_{i}$ for each of many items. For example, a key problem in sponsored search is to estimate the click through rate (CTR) of each of billions of query-ad pairs. Most common methods, though, only give a point estimate of each $\theta_{i}$. A posterior distribution for each $\theta_{i}$ is usually more useful but harder to get. We present a simple post-processing technique that takes point estimates or scores $t_{i}$ (from any method) and estimates an approximate posterior for each $\theta_{i}$. We build on the idea of calibration, a common post-processing technique that estimates $\mathrm{E}\left(\theta_{i}\!\!\bigm|\!\! t_{i}\right)$. Our method, second order calibration, uses empirical Bayes methods to estimate the distribution of $\theta_{i}\!\!\bigm|\!\! t_{i}$ and uses the estimated distribution as an approximation to the posterior distribution of $\theta_{i}$. We show that this can yield improved point estimates and useful accuracy estimates. The method scales to large problems - our motivating example is a CTR estimation problem involving tens of billions of query-ad pairs.
昆虫学报 , 2014,
Abstract: 【目的】尽管一雌多雄在瓢虫科中常见,但各研究中获得的数据不足以解释雌虫多次交配和一雌多雄的一般适应性意义或适合度后果。本研究以温度为胁迫因子,旨在评价一雌多雄的某些益处(如增加的适合度)是否可传递给后代。【方法】本研究检测了黄斑盘瓢虫Coelophorasaucia(Mulsant)3种交配处理中的适合度:一雌一雄(与同一雄虫交配5次,1次/d),先后一雌多雄(与5头不同的雄虫依次交配5次,即每天与新的雄虫交配1次),以及同时一雌多雄(放进5头雄虫,任由雌虫选择雄虫,交配5次,1次/d)。观察了各交配处理不同温度下(25,27和30℃)繁殖力、卵的育性、后代发育和存活。【结果】结果表明,经历一雌多雄然后进行交配选择或竞争的雌性的繁殖能力最强,后代能在更广温度范围内最好地适应发育和存活。但先后一雌多雄交配的雌性与一雌一雄交配的雌性的繁殖能力相似。【结论】结果说明,在无交配选择或雄性竞争的条件下,一雌多雄的益处不明显。这可能是由于在依次射精的雄性间存在精子竞争,或由于雌性的隐性选择。据我们所知,本研究中观察发现的无交配选择时不表现一雌多雄的益处的现象,之前在昆虫中未观察到过。
昆虫学报 , 2015,
Abstract: 【目的】印度次大陆是世界上最脆弱的地理景观。气候条件的略微变动可能对其季节周期可能产生不良影响,并引起农业生态系统中蚜虫的大暴发。七星瓢虫CoccinellaseptempunctataL.和狭臀瓢虫C.transversalisFab.是该次大陆上广泛分布、同域发生的两种食蚜性瓢虫。【方法】设计异地试验,来探究同种和/或异种组合时的这两种瓢虫用共同的猎物资源(豌豆蚜)饲养时,对增加的温度(15,20,25,30和35℃)和光周期(8L:16D,12L:12D和16L:8D)的响应。【结果】结果表明,在这5个不同温度和3个不同光周期条件下,同种或异种组合时这两种瓢虫表现出了拮抗作用。尽管表现出拮抗作用,但是同种或异种组合的两捕食动物在25℃和长光周期(16L:8D)条件下消耗、转化和利用的猎物生物量最大。然而,它们的猎物消耗率、转化效率和生长速率在异种组合中最高。在5个不同温度下,4龄幼虫均更有效地利用猎物生物量,将其转变成自身生物量,而雌成虫在3个不同光周期条件下也是如此。【结论】因此可以推断,增加的温度和光周期条件可能不会阻止同种和异种组合中的瓢虫发生拮抗作用,但是在25℃和长光周期(16L:8D)条件下,相互作用的瓢虫的猎物消耗量和利用率为最佳。
The lateral neck radiograph for an impacted fish bone in the aero-digestive tract: Going back to basics  [PDF]
Dushyant Shetty, David AT Gay
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.512A104

Aim: To evaluate the radioopacity of fish bones from a number of species using digital radiography in order to establish whether advances in acquisition and interpretative techniques have affected the radiologist’s ability to detect impacted fish bones. Methods: The bones from six species of fish commonly consumed in the United Kingdom were radiographed using a soft tissue neck phantom by means of a digital radiographic X-ray tube. The images were looked at by 15 radiology consultants and registrars who determined whether the bones were visible or not using General Electric (GE) PACS workstations. Results: The radio-graphed bones from all six species of fish were visible by all 15 (100%) radiology registrars and consultants. Conclusion: Digital radiogramphy and modern PACS workstations have meant that fish bones can be visualized irrespective of species. The lateral neck radiograph therefore may still have an important role in the investigation of impacted fish bones in the aerodigestive tract.

A Study on the Blended Wax Patterns in Investment Casting Process
Omkar Bemblage,D. Benny Karunakar
Lecture Notes in Engineering and Computer Science , 2011,
On Calibrated Predictions for Auction Selection Mechanisms
H. Brendan McMahan,Omkar Muralidharan
Computer Science , 2012,
Abstract: Calibration is a basic property for prediction systems, and algorithms for achieving it are well-studied in both statistics and machine learning. In many applications, however, the predictions are used to make decisions that select which observations are made. This makes calibration difficult, as adjusting predictions to achieve calibration changes future data. We focus on click-through-rate (CTR) prediction for search ad auctions. Here, CTR predictions are used by an auction that determines which ads are shown, and we want to maximize the value generated by the auction. We show that certain natural notions of calibration can be impossible to achieve, depending on the details of the auction. We also show that it can be impossible to maximize auction efficiency while using calibrated predictions. Finally, we give conditions under which calibration is achievable and simultaneously maximizes auction efficiency: roughly speaking, bids and queries must not contain information about CTRs that is not already captured by the predictions.
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