Co-Evolution of Content Spread and Popularity in Mobile Opportunistic Networks

We consider a setting in which a single item of content is disseminated in a population of mobile nodes by opportunistic copying when pairs of nodes come in radio contact. The nodes in the population may either be interested in receiving the content (referred to as destinations) or not yet interested in receiving the content (referred to as relays). We consider a model for the evolution of popularity, the process by which relays get converted into destinations. A key contribution of our work is to model and study the joint evolution of content popularity and its spread in the population. Copying the content to relay nodes is beneficial since they can help spread the content to destinations, and could themselves be converted into destinations. We derive a fluid limit for the joint evolution model and obtain optimal policies for copying to relay nodes in order to deliver content to a desired fraction of destinations, while limiting the fraction of relay nodes that get the content but never turn into destinations. We prove that a time-threshold policy is optimal for controlling the copying to relays, i.e., there is an optimal time-threshold up to which all opportunities for copying to relays are exploited, and after which relays are not copied to. We then utilize simulations and numerical evaluations to provide insights into the effects of various system parameters on the optimally controlled co-evolution model.

Investigation of High-Speed Combustible Gas Ignited by a Hot Gas Jet Produced in the Shock Tube

The high-speed combustible gas ignited by a hot gas jet, which is induced by shock focusing, was experimentally investigated. By use of the separation mode of shock tube, the test section of a single shock tube is split into two parts, which provide the high-speed flow of combustible gas and pilot flame of hot gas jet, respectively. In the interface of two parts of test sections the flame of jet was formed and spread to the high-speed combustible gas. Two kinds of the ignitions, 3-D “line-flame ignition” and 2-D “plane-flame ignition”, were investigated. In the condition of 3-D “lineflame ignition” of combustion, thicker hot gas jet than pure air jet, was observed in schlieren photos. In the condition of 2-D “plane-flame ignition” of combustion, the delay time of ignition and the angle of flame front in schlieren photos were measured, from which the velocity of flame propagation in the high-speed combustible gas is estimated in the range of 30–90 m/s and the delay time of ignition is estimated in the range of 0.12–0.29 ms.

PICES Press, Vol. 7, No. 1, January 1999

Taking stock and looking to the future - note from former PICES Chairman The state of the western North Pacific in the first half of 1998 The status of the Bering Sea in the first eight month of 1998 The state of the eastern North Pacific since February 1998 Highlights of PICES VII, review of SB activities and future workplan The second PICES Workshop on the Okhotsk Sea and ajacent area PICES-GLOBEC Climate Change and Carrying Capacity Program: A report from PICES VII Data management for the CCCC Program Report on GOOS Living Marine Resource Panel Meeting Photos from PICES VII Vjatcheslav Petrovich Shuntov GLOBEC Canada: Who we are, what we’ve been doing and where we’re headed The Ocean Carrying Capacity Research Program (OCC) at the Alaska Fisheries Science Center, Auke Bay Laboratory, Juneau, Alaska JAMSTEC research activities in the northern North Pacific People and events

Investigation of High-Speed Combustible Gas Ignited by a Hot Gas Jet Produced in the Shock Tube

The high-speed combustible gas ignited by a hot gas jet, which is induced by shock focusing, was experimentally investigated. By use of the separation mode of shock tube, the test section of a single shock tube is split into two parts, which provide the high-speed flow of combustible gas and pilot flame of hot gas jet, respectively. In the interface of two parts of test sections the flame of jet was formed and spread to the high-speed combustible gas. Two kinds of the ignitions, 3-D "line-flame ignition" and 2-D "plane-flame ignition", were investigated. In the condition of 3-D "line-flame ignition" of combustion, thicker hot gas jet than pure air jet, was observed in schlieren photos. In the condition of 2-D "plane-flame ignition" of combustion, the delay time of ignition and the angle of flame front in schlieren photos were measured, from which the velocity of flame propagation in the high-speed combustible gas is estimated in the range of 30-90m/s and the delay time of ignition is estimated in the range of 0.12-0.29ms.

A comparison of seafloor habitats and associated benthic fauna in areas open and closed to bottom trawling along the central California Continental Shelf

Executive Summary: A number of studies have shown that mobile, bottom-contact fishing gear (such as otter trawls) can alter seafloor habitats and associated biota. Considerably less is known about the recovery of these resources following such disturbances, though this information is critical for successful management. In part, this paucity of information can be attributed to the lack of access to adequate control sites – areas of the seafloor that are closed to fishing activity. Recent closures along the coast of central California provide an excellent opportunity to track the recovery of historically trawled areas and to compare recovery rates to adjacent areas that continue to be trawled. In June 2006 we initiated a multi-year study of the recovery of seafloor microhabitats and associated benthic fauna inside and outside two new Essential Fish Habitat (EFH) closures within the Cordell Bank and Gulf of the Farallones National Marine Sanctuaries. Study sites inside the EFH closure at Cordell Bank were located in historically active areas of fishing effort, which had not been trawled since 2003. Sites outside the EFH closure in the Gulf of Farallones were located in an area that continues to be actively trawled. All sites were located in unconsolidated sands at equivalent water depths. Video and still photographic data collected via a remotely operated vehicle (ROV) were used to quantify the abundance, richness, and diversity of microhabitats and epifaunal macro-invertebrates at recovering and actively trawled sites, while bottom grabs and conductivity/temperature/depth (CTD) casts were used to quantify infaunal diversity and to characterize local environmental conditions. Analysis of still photos found differences in common seafloor microhabitats between the recovering and actively trawled areas, while analysis of videographic data indicated that biogenic mound and biogenic depression microhabitats were significantly less abundant at trawled sites. Each of these features provides structure with which demersal fishes, across a wide range of size classes, have been observed to associate. Epifaunal macro-invertebrates were sparsely distributed and occurred in low numbers in both treatments. However, their total abundance was significantly different between treatments, which was attributable to lower densities at trawled sites. In addition, the dominant taxa were different between the two sites. Patchily-distributed buried brittle stars dominated the recovering site, and sea whips (Halipteris cf. willemoesi) were most numerous at the trawled site though they occurred in only five of ten transects. Numerical classification (cluster analysis) of the infaunal samples also revealed a clear difference between benthic assemblages in the recovering vs. trawled areas due to differences in the relative abundances of component species. There were no major differences in infaunal species richness, H′ diversity, or J′ evenness between recovering vs. trawled site groups. However, total infaunal abundance showed a significant difference attributable to much lower densities at trawled sites. This pattern was driven largely by the small oweniid polychaete Myriochele gracilis, which was the most abundant species in the overall study region though significantly less abundant at trawled sites. Other taxa that were significantly less abundant at trawled sites included the polychaete M. olgae and the polychaete family Terebellidae. In contrast, the thyasirid bivalve Axinopsida serricata and the polychaetes Spiophanes spp. (mostly S. duplex), Prionospio spp., and Scoloplos armiger all had significantly to near significantly higher abundances at trawled sites. As a result of such contrasting species patterns, there also was a significant difference in the overall dominance structure of infaunal assemblages between the two treatments. It is suggested that the observed biological patterns were the result of trawling impacts and varying levels of recovery due to the difference in trawling status between the two areas. The EFH closure was established in June 2006, within a month of when sampling was conducted for the present study, however, the stations within this closure area are at sites that actually have experienced little trawling since 2003, based on National Marine Fishery Service trawl records. Thus, the three-year period would be sufficient time for some post-trawling changes to have occurred. Other results from this study (e.g., similarly moderate numbers of infaunal species in both areas that are lower than values recorded elsewhere in comparable habitats along the California continental shelf) also indicate that recovery within the closure area is not yet complete. Additional sampling is needed to evaluate subsequent recovery trends and persistence of effects. Furthermore, to date, the study has been limited to unconsolidated substrates. Ultimately, the goal of this project is to characterize the recovery trajectories of a wide spectrum of seafloor habitats and communities and to link that recovery to the dynamics of exploited marine fishes. (PDF has 48 pages.)

Comments on hydrographic and topographic LIDAR acquisition and merging with multibeam sounding data acquired in the Olympic Coast National Marine Sanctuary

In April 2005, a SHOALS 1000T LIDAR system was used as an efficient alternative for safely acquiring data to describe the existing conditions of nearshore bathymetry and the intertidal zone over an approximately 40.7 km2 (11.8 nm2) portion of hazardous coastline within the Olympic Coast National Marine Sanctuary (OCNMS). Data were logged from 1,593 km (860 nm) of track lines in just over 21 hours of flight time. Several islands and offshore rocks were also surveyed, and over 24,000 geo-referenced digital still photos were captured to assist with data cleaning and QA/QC. The 1 kHz bathymetry laser obtained a maximum water depth of 22.2 meters. Floating kelp beds, breaking surf lines and turbid water were all challenges to the survey. Although sea state was favorable for this time of the year, recent heavy rainfall and a persistent low-lying layer of fog reduced acquisition productivity. The existence of a completed VDatum model covering this same geographic region permitted the LIDAR data to be vertically transformed and merged with existing shallow water multibeam data and referenced to the mean lower low water (MLLW) tidal datum. Analysis of a multibeam bathymetry-LIDAR difference surface containing over 44,000 samples indicated surface deviations from –24.3 to 8.48 meters, with a mean difference of –0.967 meters, and standard deviation of 1.762 meters. Errors in data cleaning and false detections due to interference from surf, kelp, and turbidity likely account for the larger surface separations, while the remaining general surface difference trend could partially be attributed to a more dense data set, and shoal-biased cleaning, binning and gridding associated with the multibeam data for maintaining conservative least depths important for charting dangers to navigation. (PDF contains 27 pages.)

Ortsbezogene Informationen in Internet-Datenbanken - das Beispiel "Baltic SeaWeb"

Whoever in future will need information about a location or an area, either literature, measurement data, photos or administrative information, might only click on that spot on a screen map in the internet. A search programme started thereby will offer all available information in databanks. A step forward to such a solution, to the retrieval of location related literature and measurement data from different kinds of databanks, is presented by the project “Baltic Sea Web” (http://www.baltic.vtt.fi/ demonstrator/index.html). The basic idea was to make the available information about a certain location accessible via a link of their geographical coordinates, longitude and latitude, to a map in a web browser

The River Endrick - then and now, monitoring by photography

A major survey of the River Endrick was carried out in 1959-60. This survey was repeated three decades later in 1989-90 and comparisons were made of the fauna at the two times of sampling. During both surveys, photographs were taken of all the sampling sites and the objective of the present paper is to compare some of these photographs and discuss the value of photography in studies of river ecology. The sites used for photographic comparison were not chosen originally for that purpose but as appropriate places on the river from source to mouth to study its ecology. The pairs of photos now available have proved of interest and value and some lessons have been learned in relation to the selection of sites for any future photographic studies. Ideally photos should be taken in more than one season of the year as much of the river can be obscured by riparian trees and shrubs during the vegetative season. The exact position from which each photograph is taken is also a major factor to be considered.

BLOG: da Internet à sala de aula

Os diários de escrita íntima constituem tipo de texto do domínio confessional. Apresentam narrativas pessoais com características específicas ao gênero, como datação, marcas de subjetividade, escrita informal e coloquialidade. Durante muitos anos, eram escritos em cadernos e guardados a sete chaves por seus autores para que não fossem lidos por outras pessoas. Por volta dos anos 80, surgiram as agendas de adolescentes. Aproveitando o modelo pré-definido industrialmente, as agendas eram preenchidas dia a dia, como um diário, mas com a novidade do acréscimo de elementos semióticos, como fotos, papéis de bala, recortes de revistas, entre outros. Além disso, traziam como diferencial a presença de um leitor participativo: os textos eram compartilhados com amigos, e bilhetes e comentários eram escritos nas páginas das agendas. Com o advento da Internet, o diário e a agenda se fundem no blog que aproveita os recursos do suporte virtual para tornar o gênero interativo, hipertextual e multimídia, acentuando o processo de leitura e de escrita nos jovens produtores de blogs. Paralelamente, a escrita se torna grande ferramenta de comunicação no ambiente virtual, adquirindo características peculiares em função da rapidez na comunicação e da economia de digitação. A partir da teoria de Bakthin sobre gêneros do discurso e do conceito de gêneros digitais de Marcuschi, a pesquisa apresenta como objeto perceber e elencar categorias pertinentes aos gêneros diário e blog para analisá-las e compará-las, na intenção de mapear um possível percurso dos diários aos blogs de adolescentes, discutindo o contraste público-privado na escrita íntima, bem como suas principais marcas linguísticas, percebendo vantagens e desvantagens de sua utilização como ferramenta auxiliar no processo de aprendizagem da escrita e da leitura de Língua Portuguesa. A pesquisa foi motivada pela discussão de que a escrita digital pode prejudicar o desenvolvimento da produção textual de jovens em formação, o que não se confirmou, visto que a estrutura sintática da língua se mantém, e que a variação acontece apenas no nível vocabular, não interferindo na comunicação. Os resultados apontam para a utilização de blogs na educação como complementação do material pedagógico e como incentivo à leitura, à escrita, à construção da argumentação e do posicionamento crítico, aproximando a escola da vida cotidiana dos estudantes

The Forbidden Quantum Adder

Quantum information provides fundamentally different computational resources than classical information. We prove that there is no unitary protocol able to add unknown quantum states belonging to different Hilbert spaces. This is an inherent restriction of quantum physics that is related to the impossibility of copying an arbitrary quantum state, i.e., the no-cloning theorem. Moreover, we demonstrate that a quantum adder, in absence of an ancillary system, is also forbidden for a known orthonormal basis. This allows us to propose an approximate quantum adder that could be implemented in the lab. Finally, we discuss the distinct character of the forbidden quantum adder for quantum states and the allowed quantum adder for density matrices.

Characteristics of large-sized ruby crystal grown by temperature gradient technique

Large ruby with the size of circle divide75 x 45 mm was grown by temperature gradient technique for the first time. Absorption spectrum was carried out in the range of 190-800 nm by spectrophotometer, and the concentration spatial distribution of Cr3+ in ruby was calculated from the absorption coefficient that based on the Beer-Lambert's Law. Cr3+ ions gradually increase alone both the growth axis and the radial direction. The shape and ingredient of the inclusions were measured by means of Leitz ride field microscopy and scanning electron microscopy. Lane photos and X-ray omega scan show the good quality of as grown ruby. The optimized growth conditions were pointed out based on the observation. (C) 2004 Elsevier B.V. All rights reserved.

Avaliação e cotidiano escolar: usos e desusos da Provinha Brasil na alfabetização

Este estudo foi realizado em uma turma do 2 ano do ensino fundamental, em uma escola pública do município de Duque de Caxias. O trabalho buscou pistas e indícios dos possíveis efeitos e implicações da Provinha Brasil no cotidiano escolar, procurando compreender como elas são ressignificadas pelos sujeitos ordinários, praticantes do cotidiano escolar. Buscou, também, identificar práticas diferenciadas no espaçotempo dos processos de ensinaraprender da sala de aula, além de discutir outras práticas de avaliação utilizadas na alfabetização e suas contribuições para a aprendizagem dos/as alunos/as. No campo teórico-metodológico, Morin (2012); Ginzburg (1989); Certeau (2012);Alves (2001) e Esteban (2001, 2006,2009) proporcionaram as âncoras para investir no desafio da pesquisa do cotidiano.Foram utilizadas a observação participante, as conversas/entrevistas, análise de documentos e fotografias. O acesso às informações forneceu material necessário para tecer os (des) afios da pesquisa. Como indício reativo e, também, de resistência, tanto a escola como a professora da turma 201, demonstraram indiferença, quanto ao uso da Provinha Brasil como diagnóstico e ajuda no planejamento pedagógico, o que implica desusos. Nas conversas, foi perceptível o quanto as políticas de avaliação afetam diretamente a subjetividade dos/as professores/as, que se mostraram ressentidos diante da desconsideração de seus saberes, de sua profissionalidade e da perda de sua autonomia. As práticas investigadas na turma 201,transbordaram as barreiras da avaliação e revelaram a complexidade e multiplicidade dos fios que tecem o cotidiano escolar. Quanto aos processos avaliativos desenvolvidos pela docente na turma e que também foram objetos de análise nesse trabalho, podemos considerar que, tanto as avaliações diagnósticas, como os relatórios descritivos, demonstraram serem insuficientes para servirem como auxiliadores do processo de ensino e aprendizagem, visto que a avaliação no sentido em que é realizada fica dissociada do processo de ensino e aprendizagem. E, na contramão da lógica que valoriza e procura empurrar os sujeitos para a competição individual, foram encontradas ações coletivas e compartilhadas dos/as alunos/as, que astuciosamente se aproveitam de cada brecha, que a rotina escolar lhes oferecem, inventando outras formas de aprenderensinar, num processo de auto-organização, a fim de conquistar a tão sonhada alfabetização.

De Mercator ao Googlemaps: Mapas colaborativos digitais no ensino e aprendizagem de geografia

Recentemente as tecnologias digitais de informação e comunicação vêm promovendo alterações na forma como os mapas são produzidos, o que pode ser uma fonte de renovação na educação geográfica em tempos de cibercultura. Nos últimos anos, aplicativos e sites voltados para o mapeamento on-line tornaram-se mais uma forma de expressão da cultura digital. Esta dissertação consiste em uma investigação acerca das possíveis mediações das cartografias multimídias e colaborativas, construídas através de interfaces da internet, em processos de ensino e aprendizagem de geografia. Os mapas colaborativos digitais são representações cartográficas produzidas de forma interativa, descentralizada e em rede. Eles permitem a inserção colaborativa de conteúdos hipermidiáticos (textos, fotos, vídeos) georreferenciados e constituem uma forma alternativa e potencialmente subversiva de produção cartográfica. A pesquisa realizada com alunos do nono ano de uma escola da Rede Municipal de Itaboraí se deu a partir do desenvolvimento de um projeto de mapeamento da região onde os alunos vivem. Os resultados revelaram que estas práticas cartográficas podem contribuir para a superação do atual mal-estar na relação entre jovens e a cultura escolar, bem como favorecer a construção de práticas pedagógicas comprometidas com a formação de cidadãos críticos e engajados.

Comunidade de mamíferos de médio e grande porte em um mosaico de fitofisionomias na Mata Atlântica no estado do Espírito Santo, Brasil

A Mata Atlântica é considerada como um dos cinco hotspots mais diversos, sendo um conjunto complexo de ecossistemas que abriga uma parcela significativa da diversidade biológica do Brasil. O Estado do Espírito Santo, localizado na região Sudeste, possuía quase 90% de sua superfície coberta por Mata Atlântica, entretanto com o processo de colonização portuguesa, ocupação do território e industrialização, restou apenas 8% da cobertura florestal original. Com toda a informação existente acerca das espécies neotropicais de mamíferos de médio e grande porte ainda há muitas lacunas no nosso conhecimento. Nesse sentido, esta dissertação foi desenvolvida em quatro capítulos com o objetivo de realizar um levantamento de dados de riqueza, composição, abundância, densidade populacional, período de atividade, distribuição e uso do hábitat por espécies de mamíferos de médio e grande porte, da Reserva Natural Vale (RNV), norte do Espírito Santo. Espera-se que as informações aqui geradas possam contribuir com o incremento no conhecimento da ecologia dos mamíferos neotropicais, bem como fornecer informações desse grupo para subsidiar as políticas e ações ambientais que visem à conservação da biodiversidade. Para este estudo foi realizado amostragens mensais no período de abril de 2013 até junho de 2014 na RNV, através de armadilhamento fotográfico (39 armadilhas fotográficas) e também transecções lineares Os registros obtidos nas39 armadilhas fotográficas resultaram em um total de 7.020 dias de monitoramento. Foram observadas 23245 fotos de 26 espécies de mamíferos de médio e grande porte. Uma maior riqueza e frequência de registros ocorreram nas armadilhas estabelecidas na região norte da RNV. A distância do recurso hídrico estava positivamente relacionada com a composição de mamíferos e a quantidade de registros de caça no presente estudo teve um efeito marginalmente negativo na frequência de registros nas regiões oeste e sul, onde apresentaram uma maior incidência de caça. Nossos resultados mostram que essas espécies não estão distribuídas uniformemente dentro da reserva, com a ocupação das mesmas tendo sido afetada por quatro principais covariáveis: (1) distância entre árvores; (2) distância da estrada; (3) distância do recurso hídrico mais próximo e (4) densidade de lianas por hectare. A detectabilidade das espécies que são consideradas cinegéticas foi afetada pelo histórico de registros de caça. A maioria das espécies registradas que tiveram uma probabilidade de ocupação alta são raras ou até mesmo localmente extintas em outras áreas de domínio da Mata Atlântica. Adicionalmente nossos dados confirmam que a RNV abriga uma fauna de mamíferos de médio e grande porte rica, incluindo grandes herbívoros, dispersores de sementes e alguns carnívoros. Embora o estudo tenha sido realizado em apenas uma área, vale lembrar que a RNV, juntamente com a ReBio Sooretama, formam o maior bloco de área protegida dentro do estado do Espírito Santo e também um dos maiores blocos de Mata de Tabuleiro. Assim, para a conservação das espécies que habitam a RNV, é preciso considerar não apenas a reserva isolada, mas todo o bloco Linhares-Sooretama, uma vez que estão conectados permitirão o incremento populacional e as trocas genéticas entre as populações. Somente desse modo será aumentada a probabilidade de sobrevivência e manutenção das espécies em longo prazo, das espécies de mamíferos de médio e grande porte

Some new bounds on eigenvalues of the Hadamard product and the Fan product of matrices

Let A and B be nonsingular M-matrices. A lower bound on the minimum eigenvalue q(B circle A(-1)) for the Hadamard product of A(-1) and B, and a lower bound on the minimum eigenvalue q(A star B) for the Fan product of A and B are given. In addition, an upper bound on the spectral radius rho(A circle B) of nonnegative matrices A and B is also obtained. These bounds improve several existing results in some cases and the estimating formulas are easier to calculate for they are only depending on the entries of matrices A and B. (C) 2009 Elsevier Inc. All rights reserved.