1,646 research outputs found

    Asymptotic Symmetries, Holography and Topological Hair

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    Asymptotic symmetries of AdS4_4 quantum gravity and gauge theory are derived by coupling the dual CFT3_3 to Chern-Simons gauge theory and 3D gravity in a "probe" large-level limit. The infinite-dimensional symmetries are shown to arise when one is restricted to boundary subspaces with effectively two-dimensional geometry. A canonical example of such a restriction occurs within the 4D subregion described by a Wheeler-DeWitt wavefunctional of AdS4_4 quantum gravity. An AdS4_4 analog of Minkowski "super-rotation" asymptotic symmetry is probed by 3D Einstein gravity, yielding CFT2_2 structure, via AdS3_3 foliation of AdS4_4 and the AdS3_3/CFT2_2 correspondence. The maximal asymptotic symmetry is however probed by 3D conformal gravity. Both 3D gravities have Chern-Simons formulation, manifesting their topological character. Chern-Simons structure is also shown to be emergent in the Poincare patch of AdS4_4, as soft/boundary limits of 4D gauge theory, rather than "put in by hand", with a finite effective Chern-Simons level. Several of the considerations of asymptotic symmetry structure are found to be simpler for AdS4_4 than for Mink4_4, such as non-zero 4D particle masses, 4D non-perturbative "hard" effects, and consistency with unitarity. The last of these, in particular, is greatly simplified, because in some set-ups the time dimension is explicitly shared by each level of description: Lorentzian AdS4_4, CFT3_3 and CFT2_2. The CFT2_2 structure clarifies the sense in which the infinite asymptotic charges constitute a useful form of "hair" for black holes and other complex 4D states. An AdS4_4 (holographic) "shadow" analog of Minkowski "memory" effects is derived. Lessons from AdS4_4 provide hints for better understanding Minkowski asymptotic symmetries, the 3D structure of its soft limits, and Minkowski holography.Comment: typos corrected, references added, discussions of boundary conditions corrected and clarifie

    Mobile Robot Path Planning in Static Environment

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    The success of Particle Swarm Optimization (PSO) and Genetic algorithm (GA) as single objective optimizer has motivated researchers to extend the use of this bio- inspired techniques to other areas. One of them is multi-objective optimization. As a part of this review we present a classification of the approaches and identify the main approaches here. We describe useful performance measures and simulation results of conventional Genetic algorithm and PSO. We extend this to multi-objective genetic algorithm and PSO. This means that GA and PSO optimizes path based on two criteria: length and difficult. Another method that has new to this field of research is the Artificial Potential field method. In this method the entire space is supposed to contain a potential field and we calculate the net force that is acted upon the robot to reach its goal

    Post-harvest losses in mandarin orange: A case study of Dhankuta District, Nepal.

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    Worldwide postharvest fruit and vegetables losses are as high as 30 to 40% and even much higher in developing countries like Nepal. A systematic survey was conducted to assess the extent of loss due to post harvest conditions in oranges at field, transport, storage and market levels during October to January, 2011. The survey data were collected using oral questionnaires, personal interviews, group discussions and informal observation in the field and Krishi Bazar, Dharan. The production of oranges in Dhankuta this year was found to be reduced by 40 to 50% than previous year which was observed to be followed by alternate pattern. Consequently, the price was doubled this year. The post harvest loss was found to be 46% from harvesting to distribution. The losses during harvesting, transportation, grading, packaging and marketing were found to be 7, 25, 3, 1 and 5% maximum, respectively. The storage losses were found to be 5% during 2 to 4 days in Krish Bazar while 40.1% during 21 days experimental condition in room. The losses in experimental condition comprised 15.02% evaporation loss, 14.34% pathological loss and 10.74% other losses. The most observed disease was fungal attack in oranges. Reducing postharvest losses is very important; ensuring that sufficient food, both in quantity and in quality is available to every inhabitant in our planet. Postharvest horticulturists need to coordinate their efforts with those of production horticulturists, agricultural marketing economists, engineers, food technologists, and others who may be involved in various aspects of the production and marketing system

    Cloning and sequencing of complete τ-crystallin cDNA from embryonic lens of Crocodylus palustris

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    τ-Crystallin is a taxon-specific structural protein found in eye lenses. We present here the cloning and sequencing of complete τ-crystallin cDNA from the embryonic lens of Crocodylus palustris and establish it to be identical to the τ-enolase gene from non-lenticular tissues. Quantitatively, the τ-crystallin was found to be the least abundant crystallin of the crocodilian embryonic lenses. Crocodile τ-crystallin cDNA was isolated by RT-PCR using primers designed from the only other reported sequence from duck and completed by 5'- and 3'-rapid amplification of cDNA ends (RACE) using crocodile gene specific primers designed in the study. The complete τ-crystallin cDNA of crocodile comprises 1305 bp long ORF and 92 and 409 bp long untranslated 5'- and 3'-ends respectively. Further, it was found to be identical to its putative counterpart enzyme τ-enolase, from brain, heart and gonad, suggesting both to be the product of the same gene. The study thus provides the first report on cDNA sequence of τ-crystallin from a reptilian species and also re-confirms it to be an example of the phenomenon of gene sharing as was demonstrated earlier in the case of peking duck. Moreover, the gene lineage reconstruction analysis helps our understanding of the evolution of crocodilians and avian species

    Prevalence of prehypertension and hypertension among the adults in South Asia: A multinomial logit model

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    Hypertension has been the most common non-communicable disease in low and middle-income countries for the past two decades, increasing cardiovascular and renal disease risk. Urbanization, aging, dietary and lifestyle changes, high illiteracy rates, poor access to health facilities, poverty, high costs of drugs, and social stress have contributed to an increase in the prevalence of hypertension in developing countries. Nonetheless, little is known about the comprehensive risk factors associated with prehypertension and hypertension among economically active adult populations of South Asia, such as India, Nepal, and Bangladesh. This paper uses the Demographic and Health Survey data of 637,396 individuals from India (2019–21), 8,924 from Nepal (2016), and 8,613 from Bangladesh (2017–18) to examine the prevalence and driver of prehypertension and hypertension. We analyze the prevalence of prehypertension because it leads to hypertension and is directly related to cardiovascular disease, and many people live with it for prolonged periods without realizing it. The paper finds, among other things, that the prevalence of prehypertension and hypertension among adults (18–49 years) is 43.2 and 14.9% in India, 35.1% and 19.8% in Bangladesh, and 25.2% and 13.8% in Nepal, respectively. Better educated, wealthy individuals living in urban areas of developing economies in the South Asian region are more likely to have prehypertension and hypertension. The paper suggests the urgent need to launch preventive programs to reduce prehypertension before it develops to be hypertension as a precautionary measure. Thus, such measures shall help to prevent hypertension, thereby improving the overall wellbeing of individuals and families

    Community-based management of severe acute malnutrition in India: new evidence from Bihar.

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    BACKGROUND: An estimated one-third of the world's children who are wasted live in India. In Bihar state, of children -2 SDs and MUAC >110 mm. These variables changed in July 2010 to admission on the basis of an MUAC <115 mm and discharge at an MUAC ≥120 mm. Uncomplicated SAM cases were treated as outpatients in the community by using a WHO-standard, ready-to-use, therapeutic lipid-based paste produced in India; complicated cases were treated as inpatients by using F75/F100 WHO-standard milk until they could complete treatment in the community. RESULTS: A total of 8274 children were admitted including 5149 girls (62.2%), 6613 children aged 6-23 mo (79.9%), and 87.3% children who belonged to Scheduled Caste, Scheduled Tribe, or Other Backward Caste families or households. Of 3873 children admitted under the old criteria, 41 children (1.1%) died, 2069 children (53.4%) were discharged as cured, and 1485 children (38.3%) defaulted. Of 4401 children admitted under the new criteria, 36 children (0.8%) died, 2526 children (57.4%) were discharged as cured, and 1591 children (36.2%) defaulted. For children discharged as cured, the mean (±SD) weight gain and length of stay were 4.7 ± 3.1 and 5.1 ± 3.7 g · kg(-1) · d(-1) and 8.7 ± 6.1 and 7.3 ± 5.6 wk under the old and new criteria, respectively (P < 0.01). After adjustment, significant risk factors for default were as follows: no community referral for admission, more severe wasting on admission, younger age, and a long commute for treatment. CONCLUSIONS: To our knowledge, this is the first conventional CMAM program in India and has achieved low mortality and high cure rates in nondefaulting children. The new admission criteria lower the threshold for severity with the result that more children are included who are at lower risk of death and have a smaller WHZ deficit to correct than do children identified by the old criteria. This study was registered as a retrospective observational analysis of routine program data at http://www.isrctn.com as ISRCTN13980582

    A novel hybrid approach for automated detection of retinal detachment using ultrasound images

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    Retinal detachment (RD) is an ocular emergency, which needs quick intervention to preclude permanent vision loss. In general, ocular ultrasound is used by ophthalmologists to enhance their judgment in detecting RD in eyes with media opacities which precludes the retinal evaluation. However, the quality of ultrasound (US) images may be degraded due to the presence of noise, and other retinal conditions may cause membranous echoes. All these can influence the accuracy of diagnosis. Hence, to overcome the above, we are proposing an automated system to detect RD using texton, higher order spectral (HOS) cumulants and locality sensitive discriminant analysis (LSDA) techniques. Our developed method is able to classify the posterior vitreous detachment and RD using support vector machine classifier with highest accuracy of 99.13%. Our system is ready to be tested with more diverse ultrasound images and aid ophthalmologists to arrive at a more accurate diagnosis

    On the approximability and exact algorithms for vector domination and related problems in graphs

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    We consider two graph optimization problems called vector domination and total vector domination. In vector domination one seeks a small subset S of vertices of a graph such that any vertex outside S has a prescribed number of neighbors in S. In total vector domination, the requirement is extended to all vertices of the graph. We prove that these problems (and several variants thereof) cannot be approximated to within a factor of clnn, where c is a suitable constant and n is the number of the vertices, unless P = NP. We also show that two natural greedy strategies have approximation factors ln D+O(1), where D is the maximum degree of the input graph. We also provide exact polynomial time algorithms for several classes of graphs. Our results extend, improve, and unify several results previously known in the literature.Comment: In the version published in DAM, weaker lower bounds for vector domination and total vector domination were stated. Being these problems generalization of domination and total domination, the lower bounds of 0.2267 ln n and (1-epsilon) ln n clearly hold for both problems, unless P = NP or NP \subseteq DTIME(n^{O(log log n)}), respectively. The claims are corrected in the present versio

    Vertex Cover Kernelization Revisited: Upper and Lower Bounds for a Refined Parameter

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    An important result in the study of polynomial-time preprocessing shows that there is an algorithm which given an instance (G,k) of Vertex Cover outputs an equivalent instance (G',k') in polynomial time with the guarantee that G' has at most 2k' vertices (and thus O((k')^2) edges) with k' <= k. Using the terminology of parameterized complexity we say that k-Vertex Cover has a kernel with 2k vertices. There is complexity-theoretic evidence that both 2k vertices and Theta(k^2) edges are optimal for the kernel size. In this paper we consider the Vertex Cover problem with a different parameter, the size fvs(G) of a minimum feedback vertex set for G. This refined parameter is structurally smaller than the parameter k associated to the vertex covering number vc(G) since fvs(G) <= vc(G) and the difference can be arbitrarily large. We give a kernel for Vertex Cover with a number of vertices that is cubic in fvs(G): an instance (G,X,k) of Vertex Cover, where X is a feedback vertex set for G, can be transformed in polynomial time into an equivalent instance (G',X',k') such that |V(G')| <= 2k and |V(G')| <= O(|X'|^3). A similar result holds when the feedback vertex set X is not given along with the input. In sharp contrast we show that the Weighted Vertex Cover problem does not have a polynomial kernel when parameterized by the cardinality of a given vertex cover of the graph unless NP is in coNP/poly and the polynomial hierarchy collapses to the third level.Comment: Published in "Theory of Computing Systems" as an Open Access publicatio
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