Optimal Error Correcting Delivery Scheme for Coded Caching with Symmetric Batch Prefetching

Coded caching is used to reduce network congestion during peak hours. A single server is connected to a set of users through a bottleneck link, which generally is assumed to be error-free. During non-peak hours, all the users have full access to the files and they fill their local cache with portions of the files available. During delivery phase, each user requests a file and the server delivers coded transmissions to meet the demands taking into consideration their cache contents. In this paper we assume that the shared link is error prone. A new delivery scheme is required to meet the demands of each user even after receiving finite number of transmissions in error. We characterize the minimum average rate and minimum peak rate for this problem. We find closed form expressions of these rates for a particular caching scheme namely \textit{symmetric batch prefetching}. We also propose an optimal error correcting delivery scheme for coded caching problem with symmetric batch prefetching.Comment: 9 pages and 4 figure

An Example of Poincare Symmetry with a Central Charge

We discuss a simple system which has a central charge in its Poincare algebra. We show that this system is exactly solvable after quantization and that the algebra holds without anomalies.Comment: 11 pages, Revte

The ragpicker with a social cause

Green Worms is a social enterprise on a mission to sustainably and scientifically tackle solid waste menace in the world. We envision a world free of solid waste. Jabir Karat, a post graduate in History from Delhi University lives in Thamarassery. He chose his career in waste management even though it was not his subject. On completion of his studies, he was offered the meritorious Gandhi Fellowship. He opted to work at the Andheri Slum in Mumbai and there the concept of garbage processing struck him. He also found an entrepreneur who transforms garbage into compost in TV show ‘ Satyamev Jayate’ produced by Aamir Khan. The show discusses and provides possible solutions to address social issues in India. He realized that waste is a misplaced resource. Later on he underwent training with the Environmental Protection and Service Organization led by Vellore Srinivasan near Coimbatore. Back home, he failed in establishing his new ideas. People of Thamarassery agreed to everything but were reluctant to pay nominal fees for the waste management services offered. It was easier to throw away

Elasticity and orientational order in some trans-p-n-alkoxy-α-methyl cyanophenyl cinnamates

The splay (k11), twist (k22) and bend (k33) elastic constants determined by the Freedericksz method and the orientational order parameters (s) derived from optical measurements in the nematic phase of six homologues of trans-p-n-alkoxy-α-methyl cyanophenyl cinnamates (n OMCPC) are reported. The data close to the nematic-isotropic transition point (TNI) are compared with TNI and the heats of transition (ΔH). The temperature-variation of elastic constants is discussed in terms of existing theories. The pretransitional increase in the twist and bend constants near the nematic-smectic A transition point (TNA) of 10 OMCPC has also been analysed

Central extensions, classical non-equivariant maps and residual symmetries

The arising of central extensions is discussed in two contexts. At first classical counterparts of quantum anomalies (deserving being named as "classical anomalies") are associated with a peculiar subclass of the non-equivariant maps. Further, the notion of "residual symmetry" for theories formulated in given non-vanishing EM backgrounds is introduced. It is pointed out that this is a Lie-algebraic, model-independent, concept.Comment: 8 pages, LaTex. Talk given at the International Conference "Renormalization Group and Anomalies in Gravitation and Cosmology", Ouro Preto, Brazil, March 2003. To appear in the Proceeding

Optimal Error Correcting Delivery Scheme for an Optimal Coded Caching Scheme with Small Buffers

Optimal delivery scheme for coded caching problems with small buffer sizes and the number of users no less than the amount of files in the server was proposed by Chen, Fan and Letaief ["Fundamental limits of caching: improved bounds for users with small buffers," (IET Communications), 2016]. This scheme is referred to as the CFL scheme. In this paper, the link between the server and the users is assumed to be error prone only during the delivery phase. Closed form expressions for average rate and peak rate of error correcting delivery scheme for CFL prefetching scheme is obtained. An optimal error correcting delivery scheme for caching problems employing CFL prefetching is proposed.Comment: 7 page

Autoria em discursos sobre resíduos sólidos: uma análise sobre produções audiovisuais de estudantes do ensino médio

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Programa de Pós-Graduação em Educação Científica e Tecnológica, Florianópolis, 2014.A pesquisa teve como objetivo analisar a possibilidade de produção de autoria por parte dos estudantes do ensino médio ao longo de um processo de produção de audiovisuais sobre a temática dos resíduos sólidos. Para a realização da pesquisa foi investigado um trabalho pedagógico sobre resíduos sólidos, realizado no ano de 2010, em parceria com professores de Física, Química, Biologia, Geografia e Português e que envolveu estudantes de ensino médio de uma escola pública de Florianópolis. Para esse trabalho pedagógico foi criado um ambiente virtual de aprendizagem composto por site, lista de discussão, webquest e blog. Com base no referencial da Análise de Discurso (AD) e nos estudos da Ciência, Tecnologia e Sociedade (CTS) e partindo do pressuposto que mudanças nas condições de produção de leitura e escrita pudessem favorecer a assunção da autoria dos estudantes, trabalhamos com a intertextualidade com o objetivo de favorecer a reflexão dos estudantes e abrir para uma leitura mais polissêmica e para o discurso polêmico. Os textos que foram utilizados nas discussões do projeto foram escolhidos dentro de uma perspectiva das inter-relações entre ciência, tecnologia e sociedade (CTS), pois como o tema dos resíduos sólidos envolve questões polêmicas, que exigem julgamento e posicionamento dos estudantes, essa abordagem poderia favorecer estratégias pedagógicas que estimulassem a autoria dos estudantes. Esse trabalho pedagógico resultou na produção de textos escritos e imagéticos tais como roteiros e audiovisuais. Nessa dissertação de mestrado foram analisados os produtos desse projeto de ensino como os vídeos, entre outras produções dessas vivências. A revisão bibliográfica mostrou que existe uma lacuna nas pesquisas, com relação à análise de produção de autoria em vídeos produzidos por estudantes, professores ou por ambos na área de ensino de Ciências e Tecnologia (ECT). O corpus para as análises dessa investigação foram os textos utilizados nas aulas e os textos produzidos pelos alunos. Dos 80 vídeos produzidos pelos estudantes, 36 estavam disponíveis para análise no formato DVD ou em links no youtube, postados pelos próprios estudantes. Os 36 audiovisuais foram considerados na primeira parte da análise, em que foram buscadas as características mais gerais do conjunto de audiovisuais. Considerando que a linguagem não é transparente, foram analisadas as condições de produção de leituras/escritas envolvendo a temática dos resíduos sólidos, junto às turmas desses estudantes. Também foram investigadas as possíveis relações CTS presentes nas produções audiovisuais e suas implicações para o processo de ensino/aprendizagem. Na segunda parte da análise foram considerados apenas os 4 vídeos produzidos por grupos de estudantes com maior participação no trabalho pedagógico. Foram analisados os vídeos, roteiros, paródias e as respostas desses estudantes a questões de atividades propostas no trabalho pedagógico. Os vídeos foram decompostos em seus elementos constitutivos (planos) e depois analisados utilizando o referencial teórico-metodológico da Análise de Discurso e o referencial da Análise Fílmica francesa.Abstract : The research aimed to examine the possibility of producing written by the high school students through a process of production of audiovisual on the subject solid waste. To conduct the study was investigated educational work on solid waste , held in 2010 , in partnership with faculty from physics, chemistry, biology, geography and Portuguese and involving high school students of a public school in Florianopolis . For this pedagogical work a virtual learning environment consisting of site, mailing list, blog and webquest was created. Based on the framework of Discourse Analysis and the CTS studies and assuming that changes in the production conditions of reading and writing could favor the assumption of authorship of the students we work with intertextuality in order to foster student reflection and open for more polysemic reading and for the controversial speech. The texts that were used in the project discussions were chosen from a perspective of the interrelationships between science, technology and society (STS), for as the subject of solid waste involves controversial issues that require judgment and placement of students, this approach could favor teaching strategies that encourage students authorship. This pedagogical work resulted in the production of written and image such as scripts and audiovisual texts. In this dissertation the products of this teaching project as videos, among other productions of these experiences were analyzed. The literature review showed that there is a gap in the polls, with respect to the analysis of production authoring videos produced by students , teachers or both in the area of science education and technology (ECT) . The corpus for the analysis of this survey were the texts used in classes and the texts produced by students. 80 videos produced by students, 36 were available for analysis in DVD format or links on youtube posted by the students themselves. The audiovisual 36 were considered in the first part of the analysis sought in which the more general characteristics of audiovisual set . Considering that language is not transparent, the conditions of production of reads/writes involving thematic solid waste along to the classes of these students were analyzed. We also investigated the possible relationship CTS present in audiovisual production and its implications for the teaching/learning. In the second part of the analysis included only 4 videos produced by groups of students with greater participation in educational work. Videos, scripts, parodies and responses of these students to issues of activities proposed in the pedagogical work were analyzed. The videos are broken down into their constituent elements (plans) and then analyzed using the theoretical and methodological framework of discourse analysis and benchmark analysis of Filmic French

Project Shearwater Ground Effect UAV

The Shearwater unmanned aerial vehicle is a maritime fixed-wing drone that is designed to use ground effect force generated between the aircraft and a body of water to efficiently propel itself near the surface of a body of water. Shearwater features a virtual reality pilot interface and will act as a hybrid underwater vehicle that will eventually be able to operate both above and beneath the ocean’s surface. The Shearwater team developed existing design work to produce major subsystems that culminated in a flyable functioning prototype. An existing airframe was updated with working control surfaces tested in simulation and in practice, an electrical control system, and a working virtual reality (VR) pilot view. The Shearwater team tested a practical prototype and developed an optimized virtual reality command and control system