746 research outputs found

    Globalization and its methodological discontents: Contextualizing globalization through the study of HIV/AIDS

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    There remains considerable discontent between globalization scholars about how to conceptualize its meaning and in regards to epistemological and methodological questions concerning how we can come to understand how these processes ultimately operate, intersect and transform our lives. This article argues that to better understand what globalization is and how it affects issues such as global health, we must take a differentiating approach, which focuses on how the multiple processes of globalization are encountered and informed by different social groups and with how these encounters are experienced within particular contexts. The article examines the heuristic properties of qualitative field research as a means to help better understand how the intersections of globalization are manifested within particular locations. To do so, the article focuses on three recent case studies conducted on globalization and HIV/AIDS and explores how these cases can help us to understand the contextual permutations involved within the processes of globalization

    Exploring the genomic basis of traits relevant to evolution and ecology of chestnuts (Castanea) using high-throughput DNA sequencing and bioinformatics.

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    Introduced pests and pathogens have devastated forest ecosystems in the temperate zone; in eastern North America, introduced pests and pathogens have led to the elimination of most mature elms (Ulmus), ashes (Fraxinus), hemlocks (Tsuga) and chestnuts (Castanea) over large areas where these genera were formerly abundant and important for local ecosystems. The restoration of species affected by introduced pests and pathogens requires the development and propagation of trees that possess heritable resistance. High-throughput DNA sequencing and genomics provide opportunities for researchers to identify resistance gene candidates, screen germplasm, and develop markers for marker-assisted selection in breeding programs, with the goal of restoring ecologically important wild trees to the landscape. American chestnut (Castanea dentata) is currently the focus of a major research effort that intends to restore the species by incorporating blight resistance from Chinese chestnut (Castanea mollissima), a species that is generally resistant to chestnut blight. I investigated several aspects of chestnut genomics and blight resistance with the goal of aiding the blight resistance breeding program for American chestnut. I tested a detached-leaf assay for chestnut blight resistance and learned that it may not be useful for screening advanced backcross (BC3) progeny in chestnut blight resistance breeding programs (Chapter 2). Utilizing a recent draft assembly of the Chinese chestnut reference genome, I analyzed patterns of genetic variation across regions associated with chestnut blight resistance, and found that several loci associated with blight resistance show markedly elevated nucleotide diversity in the most resistant Chinese chestnuts relative to more susceptible trees. At other blight-associated loci, genetic diversity was low in all C. mollissima (Chapter 3). This indicates that while maintaining high allelic diversity at blight resistance loci is desirable for a resistance breeding program, it may not be essential. Assessing potential unintended effects of hybrid breeding on the ecological behavior of restored chestnuts, I found that several genetic loci in third backcross (BC3) chestnut appear to affect caching decisions by squirrels due to inheritance of C. mollissima alleles that influence seed traits (Chapter 4). The reason for backcrossing in the American chestnut breeding program is to avoid the short, branchy mature form of C. mollissima. By sequencing the genomes of wild and orchard-derived Chinese chestnuts, I showed that some genomic loci under selection in orchard chestnuts (i.e., artificially selected by humans) may influence crown form (Chapter 5). This work should provide the basis for further investigations that validate the phenotypic effects of the proposed candidate genes, and utilize information on genetic polymorphisms identified here to accelerate chestnut improvement programs

    An imaging vector magnetograph for the next solar maximum

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    Researchers describe the conceptual design of a new imaging vector magnetograph currently being constructed at the University of Hawaii. The instrument combines a modest solar telescope with a rotating quarter-wave plate, an acousto-optical tunable prefilter as a blocker for a servo-controlled Fabry-Perot etalon, CCD cameras, and on-line digital image processing. Its high spatial resolution (1/2 arcsec pixel size) over a large field of view (5 by 5 arcmin) will be sufficient to significantly measure, for the first time, the magnetic energy dissipated in major solar flares. Its millisecond tunability and wide spectral range (5000 to 7000 A) enable nearly simultaneous vector magnetic field measurements in the gas-pressure-dominated photosphere and magnetically-dominated chromosphere, as well as effective co-alignment with Solar-A's X ray images. Researchers expect to have the instrument in operation at Mees Solar Observatory (Haleakala) in early 1991. They have chosen to use tunable filters as wavelength-selection elements in order to emphasize the spatial relationships between magnetic field elements, and to permit construction of a compact, efficient instrument. This means that spectral information must be obtained from sequences of images, which can cause line profile distortions due to effects of atmospheric seeing

    Developmental biomechanics and age polyethism in leaf-cutter ants.

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    Many social insects display age polyethism: young workers stay inside the nest, and only older workers forage. This behavioural transition is accompanied by genetic and physiological changes, but the mechanistic origin of it remains unclear. To investigate if the mechanical demands on the musculoskeletal system effectively prevent young workers from foraging, we studied the biomechanical development of the bite apparatus in Atta vollenweideri leaf-cutter ants. Fully matured foragers generated peak in vivo bite forces of around 100 mN, more than one order of magnitude in excess of those measured for freshly eclosed callows of the same size. This change in bite force was accompanied by a sixfold increase in the volume of the mandible closer muscle, and by a substantial increase of the flexural rigidity of the head capsule, driven by a significant increase in both average thickness and indentation modulus of the head capsule cuticle. Consequently, callows lack the muscle force capacity required for leaf-cutting, and their head capsule is so compliant that large muscle forces would be likely to cause damaging deformations. On the basis of these results, we speculate that continued biomechanical development post eclosion may be a key factor underlying age polyethism, wherever foraging is associated with substantial mechanical demands

    Skinning Injury Responses in Sweetpotato

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    In sweetpotatoes (Ipomoea batatas L. Lamb), the loss of skin from the surface of the storage roots is known as skinning injury. It is responsible for significant postharvest loss resulting from moisture increase and weight reduction, wrinkling, and susceptibility to pathogen attack. Reduced root weight by water loss is associated with a higher rate of rot predominantly occurred in the developing and underdeveloped countries which can count of 8-20% of postharvest loss. Plants have different adaptation to protect themselves against skinning injury. Lignification, suberization, and increased sugar at the wound site have been shown to be correlated with wound healing. Changing in gene expressions have been associated with skinning injury. Genes associated in the biosynthesis of lignin and suberin, protein fate, cell-wall modification, transcription and protein synthesis, and stress responses and defense have been associated with skinning injury responses in plants. Understanding the skinning injury responses and how to regulate them can be used to produce a more desirable plant resistant to skinning injury. This paper especially reviews and discusses skinning injury responses in sweetpotato, a root crop which product may severely be affected by skinning injury. Keywords: gene expression, Ipomoea batatas, lignification, postharvest loss, wounding   ABSTRAK Pada ubi jalar (Ipomoea batatas L. Lamb), cedera kulit adalah hilangnya kulit dari permukaan umbi. Cedera kulit ini bertanggung jawab atas kerugian pascapanen yang signifikan akibat peningkatan laju kelembaban dan penurunan berat umbi, pengerutan, dan kerentanan terhadap serangan patogen. Berat umbi yang berkurang karena kehilangan air dikaitkan dengan tingkat pembusukan yang lebih tinggi, terutama terjadi di negara-negara berkembang dan yang kurang berkembang dengan kehilangan hasil panen umbi 8-20%. Tanaman memiliki adaptasi yang berbeda untuk melindungi diri dari cedera kulit. Lignifikasi, suberisasi, dan peningkatan gula di lokasi pelukaan telah terbukti berkorelasi dengan penyembuhan luka. Perubahan ekspresi gen telah dikaitkan dengan cedera kulit. Gen-gen yang terlibat dalam jalur biosintesis lignin dan suberin, protein tujuan akhir, modifikasi dinding sel, transkripsi dan sintesis protein, serta respons stres dan pertahanan telah dikaitkan dengan respons cedera kulit pada tanaman. Memahami respons cedera kulit dan bagimana cara mengaturnya dapat digunakan untuk menghasilkan tanaman yang diinginkan yang tahan terhadap cedera kulit umbi. Paper ini secara khusus mengulas dan membahas respon cedera kulit pada ubi jalar, suatu tanaman umbian yang hasilnya sangat terpengaruh oleh cedera kulit. Kata kunci: ekspresi gen, Ipomoea batatas, lignifikasi, kehilangan pascapanen, pelukaa

    Globalization, Global Governance and the Social Determinants of Health: A review of the linkages and agenda for action

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    The Globalization Knowledge Network (GKN) was formed in 2005 with the purpose of examining how contemporary globalization was influencing social determinants of health. It was one of nine Knowledge Networks providing evidence-informed guidance to the work of the World Health Organization’s Commission on Social Determinants of Health (2005-2008): like most of the Knowledge Networks, its operations were financed by an external funder (in this case, the International Affairs Directorate of Health Canada, Canada’s national ministry of health). The GKN conducted two face-to-face meetings to debate, discuss, outline and review its work, and produced thirteen background papers and a Final Report. These papers and the Final Report underwent extensive internal and external peer review to ensure that their findings and policy inferences accurately reflected available evidence and scholarship. This GKN publication series was prepared under the general editorship of Ronald Labonté, with assistance from Vivien Runnels and copy-editing provided by Wayne Harding. All views expressed are exclusively those of the authors. A complete list of titles in the publication series appears on the inside back cover of this monograph

    Solar Irradiance Variations on Active Region Time Scales

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    The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance
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