7,095 research outputs found

    Spin Disorder Scattering in Nickel and Iron

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    Non-agricultural Market Access: A South Asian Perspective

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    A key element of the Doha Round of trade negotiations is liberalisation of trade in industrial products, commonly known as non-agricultural market access (NAMA). These negotiations are important for developing countries as these will determine the market access opportunities through which they can improve their growth prospects. This paper examines the key issues of NAMA from the South Asian perspective, outlines a negotiating strategy for increased market access, and spells out some policy implications.

    Insights from unifying modern approximations to infections on networks

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    Networks are increasingly central to modern science owing to their ability to conceptualize multiple interacting components of a complex system. As a specific example of this, understanding the implications of contact network structure for the transmission of infectious diseases remains a key issue in epidemiology. Three broad approaches to this problem exist: explicit simulation; derivation of exact results for special networks; and dynamical approximations. This paper focuses on the last of these approaches, and makes two main contributions. Firstly, formal mathematical links are demonstrated between several prima facie unrelated dynamical approximations. And secondly, these links are used to derive two novel dynamical models for network epidemiology, which are compared against explicit stochastic simulation. The success of these new models provides improved understanding about the interaction of network structure and transmission dynamics

    Efficacy of Methyl-eugenol as Male Attractant for Dacus dorsalis Hendel (Diptera: Tephritidae)

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    Dacus dorsalis Hendel is the predominant species of fruit-fly (99.8%) found in a carambola orchard. Population level was found to be correlated (r = 0.56) with rainfall. Infestation of fruits began 29 days after fruit set. Laboratory studies show that among the three species of fruitflies tested for attractiveness to methyl eugenol, male of D. dorsalis and D. umbrosus showed no significant difference but both are significantly different (p < 0.05) with D. cucurbitae. Virgin adult males of D. dorsalis more than 20 days old were greatly attracted to methyl eugeno

    Variation in relapse frequency and the transmission potential of Plasmodium vivax malaria

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    There is substantial variation in the relapse frequency of Plasmodium vivax malaria, with fast-relapsing strains in tropical areas, and slow-relapsing strains in temperate areas with seasonal transmission. We hypothesize that much of the phenotypic diversity in P. vivax relapses arises from selection of relapse frequency to optimize transmission potential in a given environment, in a process similar to the virulence trade-off hypothesis. We develop mathematical models of P. vivax transmission and calculate the basic reproduction number R0 to investigate how transmission potential varies with relapse frequency and seasonality. In tropical zones with year-round transmission, transmission potential is optimized at intermediate relapse frequencies of two to three months: slower-relapsing strains increase the opportunity for onward transmission to mosquitoes, but also increase the risk of being outcompeted by faster-relapsing strains. Seasonality is an important driver of relapse frequency for temperate strains, with the time to first relapse predicted to be six to nine months, coinciding with the duration between seasonal transmission peaks. We predict that there is a threshold degree of seasonality, below which fast-relapsing tropical strains are selected for, and above which slow-relapsing temperate strains dominate, providing an explanation for the observed global distribution of relapse phenotypes

    Persistence of two genotypes of Neisseria gonorrhoeae during transmission.

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    Isolates of Neisseria gonorrhoeae were tested using a highly discriminatory typing method, opa typing, to examine the genetic diversity over a 2-year study period of isolates from all consecutive patients with gonorrhea attending the Genitourinary Medicine clinic in Sheffield, United Kingdom. Two opa genotypes were detected throughout the 2-year time period and comprised 41% of all strains tested. The persistence of two opa types was investigated further to determine the apparent genetic stability, by examining the ability of isolates to undergo intragenic and intergenic recombination and mutation in vitro. Intragenic recombination or mutation involving the opa genes of N. gonorrhoeae in the selected isolates was not detected, but intergenic recombination did occur. opa genes of N. gonorrhoeae in vivo appear to diversify primarily through intergenic recombination. Intergenic recombination in vivo would require the presence of a mixed gonococcal infection, in which an individual is concurrently colonized with more than one strain of N. gonorrhoeae. We propose that the level of diversity of opa genotypes in a population is linked to the degree of sexual mixing of individuals and the incidence of mixed infections of N. gonorrhoeae

    Problem of access and rights of fishermen to water bodies in haor areas: a case study

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    Meat to water ratio used for washing was 1:3 for oil sardine and mackerel; but for pink perch and croaker, it was 1:2. Again the washing process was repeated three times for oil sardine and mackerel; but two times for pink perch and croaker. The washed meat was mixed with 2.5% NaC1 and set at +5°C and +40°C for 1, 2 and 3hrs. The gel strength and expressible water content was measured. Basing on this study, setting temperature at +40°C was selected and with respect to time 1hr for sardine and mackerel and 3hrs for pink perch and croaker was selected

    Use of Scrap Tyre as Lightweight Material In Civil Engineering Infrastructure Works

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    Load reduction effect of using lightweight material in new construction, expansion, rehabilitation or maintenance of infrastructure facilities provide advantages in term of reduction of total cost, construction time and maintenance work especially in soft ground areas
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