268 research outputs found

    On optimum stratification

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    In this manuscript, we discuss the problem of determining the optimum stratification of a study (or main) variable based on the auxiliary variable that follows a uniform distribution. If the stratification of survey variable is made using the auxiliary variable it may lead to substantial gains in precision of the estimates. This problem is formulated as a Nonlinear Programming Problem (NLPP), which turn out to multistage decision problem and is solved using dynamic programming technique

    Tamm plasmon polariton in planar structures: A brief overview and applications

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    Tamm plasmon provides a new avenue in plasmonics of interface states in planar multilayer structures due to its strong light matter interaction. This article reviews the research and development in Tamm plasmon polariton excited at the interface of a metal and a distributed Bragg reflector. Tamm plasmon offers an easy planar solution compared to patterned surface plasmon devices with huge field enhancement at the interface and does not require of any phase matching method for its excitation. The ease of depositing multilayer thin film stacks, direct optical excitation, and high-Q modes make Tamm plasmons an attractive field of research with potential practical applications. The basic properties of the Tamm plasmon modes including its dispersion, effect of different plasmon active metals, coupling with other resonant modes and their polarization splitting, and tunability of Tamm plasmon coupled hybrid modes under externally applied stimuli have been discussed. The application of Tamm plasmon modes in lasers, hot electron photodetectors, perfect absorbers, thermal emitters, light emitting devices, and sensors have also been discussed in detail. This review covers all the major advancements in this field over the last fifteen years with special emphasis on the application part

    High-pressure behavior of superconducting boron-doped diamond

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    This work investigates the high-pressure structure of freestanding superconducting (TcT_{c} = 4.3\,K) boron doped diamond (BDD) and how it affects the electronic and vibrational properties using Raman spectroscopy and x-ray diffraction in the 0-30\,GPa range. High-pressure Raman scattering experiments revealed an abrupt change in the linear pressure coefficients and the grain boundary components undergo an irreversible phase change at 14\,GPa. We show that the blue shift in the pressure-dependent vibrational modes correlates with the negative pressure coefficient of TcT_{c} in BDD. The analysis of x-ray diffraction data determines the equation of state of the BDD film, revealing a high bulk modulus of B0B_{0}=510±\pm28\,GPa. The comparative analysis of high-pressure data clarified that the sp2^{2} carbons in the grain boundaries transform into hexagonal diamond.Comment: 7 pages, 4 figure

    Impact of the invasive plant, Lantana camara, on bird assemblages at Malé Mahadeshwara Reserve Forest, South India

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    Lantana camara is an invasive species that is widespread in India. Using birds as an indicator taxon, we investigated whether Lantana invasion was correlated with changes in ecosystem health of the moist and dry deciduous forests at the Malé Madeshwara Hills, Karnataka. We studied Lantana at four densities, low, medium, and high, and a no-Lantana control. Bird species diversity, species richness, and abundance were lower at high densities of Lantana in both forest types. Evenness increased with increase in Lantana density. To better understand the observed changes in bird community composition, we segregated birds into 2 guild types: microhabitat guilds and foraging guilds. An increase in Lantana density was correlated with a decline in canopy birds (of the canopy microhabitat guilds) and insectivores (of the insectivore foraging guilds). Our results suggest that Lantana affects the structure of the bird community by decreasing diversity, and that Lantana affects certain guilds more than others

    Regulation of Marginal Zone B-Cell Differentiation by MicroRNA-146a.

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    B-cell development in the bone marrow is followed by specification into functional subsets in the spleen, including marginal zone (MZ) B-cells. MZ B-cells are classically characterized by T-independent antigenic responses and require the elaboration of distinct gene expression programs for development. Given their role in gene regulation, it is not surprising that microRNAs are important factors in B-cell development. Recent work demonstrated that deficiency of the NFκB feedback regulator, miR-146a, led to a range of hematopoietic phenotypes, but B-cell phenotypes have not been extensively characterized. Here, we found that miR-146a-deficient mice demonstrate a reduction in MZ B-cells, likely from a developmental block. Utilizing high-throughput sequencing and comparative analysis of developmental stage-specific transcriptomes, we determined that MZ cell differentiation was impaired due to decreases in Notch2 signaling. Our studies reveal miR-146a-dependent B-cell phenotypes and highlight the complex role of miR-146a in the hematopoietic system

    Are red-listed species threatened? A comparative analysis of red-listed and non-red-listed plant species in the Western Ghats, India

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    Red lists of taxa are important documents guiding the prioritization of conservation efforts. However the actual process of arriving at red lists has been contentious, because of the paucity of hard ecological data. In this article, we examine the red listing of plant species at two geographical scales: regional and local in the Western Ghats, India. At the regional level, we compared the rarity (or abundance) of the red listed and the co-occurring non-red-listed species in fifteen sites across Western Ghats. For the local level analysis, we compared the distribution and demographic profile of red-listed medicinal plants with co-occurring non-redlisted species at two field sites in the Western Ghats. At both the regional and the local scales, our analyses showed that the red-listed species, as a group are not any more disadvantaged than the non-red-listed species. Our results lay caution on the process of inclusion of species in red-lists and urge the necessity of strong field data to make the red-listing process more robust

    Functional and radiological outcome in surgically managed posterior wall and column fractures of acetabulum

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    Background: The incidence of acetabular fractures has increased following road traffic accidents. The aim of the study is to evaluate functional and radiological outcome in surgically managed posterior wall and column fractures of acetabulum.Methods: This is a prospective study done at Nizam’s Institute of Medical Sciences, Hyderabad between May 2018 and May 2020. The sample size is 20 patients between the age group 18-60 years who presented to the hospital with closed posterior wall and/or column fractures of acetabulum with or without posterior dislocation of hip joint. Functional outcome is assessed by using the modified Merle D’ Aubigne Postel clinical grading system, radiological outcome by Matta et al and perioperative complication are assessed by retrospectively analyzing medical records and radiographics examination.Results: Functional outcome according to Merle D’ Aubigne and Postel score 16 patients (75%) showed good, 3 patients (20%) showed fair, 1 patient (5%) showed poor outcome. Radiological outcome according to Matta criteria, 16 patients (75%) showed excellent quality of joint reduction, 4 patients (25%) showed good quality of reduction of joint. There was significant correlation between anatomic reduction of the joint surface and functional outcome of the patient in our study (p value <0.05).Conclusions: Accurate joint reduction is of utmost importance in reduction of posterior wall or column fractures of acetabulum as posterior wall is the weight bearing zone. Functional outcome depends on fracture type, associated injuries, selection of patient, time between injury and surgery and postoperative rehabilitation

    A Secure Data Transmission Using Efficient Aggregate Signature Scheme to Verify Data in Wireless Sensor N/W

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    We stretch an ID-based aggregate signature (IBAS) scheme for WSNs in cluster-based method . The opponent in our refuge model has the competence to presentation any alliance attacks. If an opponent can use some solitary signatures counting invalid ones to make a valid aggregate signature approximately that the attack is successful. In detail, our ID-based aggregate signature scheme not only can defend data integrity, but also can lessen bandwidth and storage cost for WSNs. we largely attention on data integrity shield, give an identity-based aggregate signature scheme with a selected verifier for wireless sensor networks. Outline not only can keep data integrity, but also can cut bandwidth and storage cost for wireless sensor networks

    Evaluating teacher-developed test and student achievement in an undergraduate statistics course: An action research

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    In this study, we used an action research approach to ascertain the degree to which first year undergraduate students had achieved the course learning outcomes of a 100-level course in statistics. In order to achieve a valid interpretation of student achievement, the researchers first had to ensure that the examination items were of reasonable quality and the examination was reliable. We analysed student papers to arrive at specific item statistics such as discrimination index and item-rest correlations. We also checked the Cronbach’s alpha reliability for the overall test. Findings related to student achievement for each learning outcome suggest that three out of the six course learning outcomes were achieved to our satisfaction. The study provided useful points for reflection for us in terms of improving our own teaching using action research. For example, university teachers can reflect on ways of improving in content areas where students’ course learning outcomes were not met. In this particular study, we found that topics such as “confidence interval” and “probability” are areas in which students’ face greater difficulty and thus would require more attention from the teaching staff. These findings provide useful insights on how university teachers can evaluate their own pedagogical practices
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