984 resultados para Alternative Sigma-factor
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Digital text benefits a wide range of learners, particularly disabled learners. For those with a visual impairment, it can be magnified or read out loud using synthetic speech. It can be navigated by heading and subheading levels, and text colours and backgrounds can be altered, both useful features for dyslexic learners. Definitions of unfamiliar words can be checked without leaving the text.
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This series of five documents is a result of research carried out with a grant from CLAUD (a group of HE librarians in South West England who are working to help create libraries accessible to users with a disability). The research involved over 60 responses representing 49 different Higher Education Institutes (HEIs).
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For many learners, course materials in standard print format are difficult to use. Getting these in alternative formats could make a big difference but how do you find out what the options are? This guide seeks to provide an overview of the alternative formats available and how you can create them.
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197 p. (Bibliogr. 189-197)
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The cod stock in the Western Baltic Sea is assessed to be overfished regarding the definitions of the UN World Summit on Sustainable Development at Johannesburg in 2002. Thus, the European Fisheries Council enforced a multi-annual management plan in 2007. Our medium term simulations over the future 10 years assume similar stock productivity as compared with the past four decades and indicate that the goals of the management plan can be achieved through TAC and consistent effort regulations. Taking account of the uncertainty in the recruitment patterns, the target average fishing mortality of age groups 3 – 6 years of F = 0.6 per year as defined in the management plan is indicated to exceed sustainable levels consistent with high long term yields and low risk of depletion. The stipulated constraint of the annual TAC variations of ±15% will dominate future fisheries management and implies a high recovery potential of the stock through continued reductions in fishing mortality. The scientific assessment of sustainable levels of exploitation and consideration in the plan is strongly advised, taking account of uncertainties attributed to environmental and biological effects. We recommend our study to be complemented with economic impact assessments including effects on by-catch species, which have been disregarded in this study. It is further demonstrated, that the goals of the management plan can alternatively be achieved by mesh size adaptations. An alternative technical option of mesh size increases to realize the required reductions in fishing mortality provides avoidance of discards of undersized fish after a few years by means of improved selectivity, another important element of the Common Fisheries Policy. However, it is emphasized that technical regulations since 1990 failed to affect the by-catch and discards of juvenile cod. In any way, the meaningful implementation of the multiannual management plan through stringent control and enforcement appears critical.
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Fischfanggeräte werden in der kommerziellen Fischerei und in der Fischereiforschung eingesetzt. In beiden Fällen werden hauptsächlich Schleppnetze verwendet. Schleppnetze sind jedoch nicht für alle Aufgabenstellungen der Fischereiforschung geeignet. Alternative in der Forschung verwendbare Untersuchungsgeräte und Methoden wurden bisher ohne überzeugenden Erfolg getestet. Schleppnetzen – insbesondere den Grundschleppnetzen der Berufsfischerei – werden sowohl die Meeresumwelt schädigende Einflüsse als auch unzureichende selektive Eigenschaften hinsichtlich Ziel- und Beifangarten nachgesagt. Die in der kommerziellen Fischerei der Ostsee verwendeten Schleppnetze üben aber nur einen geringen schädlichen Einfluss auf Bodenorganismen aus. Alternative ökosystemgerechte Fanggeräte wie Fischfallen können Schleppnetze bisher nicht ersetzen. Es werden Möglichkeiten aufgezeigt, die negativen Einflüsse auf die Meeresumwelt noch weiter zu verringern. Durch konstruktive Gestaltung der Schleppnetze (großmaschige Unterblätter im Vornetz, im Oberblatt reduzierte Grundschleppnetze) können Beifänge reduziert werden. Durch weitere Verbesserungen der Beschwerungs- und Spreizelemente an Grundschleppnetzen lassen sich die negativen Einflüsse auf den Meeresboden weiter reduzieren.
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Background: Human melanoma frequently colonizes bone marrow (BM) since its earliest stage of systemic dissemination, prior to clinical metastasis occurrence. However, how melanoma cell adhesion and proliferation mechanisms are regulated within bone marrow stromal cell (BMSC) microenvironment remain unclear. Consistent with the prometastatic role of inflammatory and angiogenic factors, several studies have reported elevated levels of cyclooxygenase-2 (COX-2) in melanoma although its pathogenic role in bone marrow melanoma metastasis is unknown. Methods: Herein we analyzed the effect of cyclooxygenase-2 (COX-2) inhibitor celecoxib in a model of generalized BM dissemination of left cardiac ventricle-injected B16 melanoma (B16M) cells into healthy and bacterial endotoxin lipopolysaccharide (LPS)-pretreated mice to induce inflammation. In addition, B16M and human A375 melanoma (A375M) cells were exposed to conditioned media from basal and LPS-treated primary cultured murine and human BMSCs, and the contribution of COX-2 to the adhesion and proliferation of melanoma cells was also studied. Results: Mice given one single intravenous injection of LPS 6 hour prior to cancer cells significantly increased B16M metastasis in BM compared to untreated mice; however, administration of oral celecoxib reduced BM metastasis incidence and volume in healthy mice, and almost completely abrogated LPS-dependent melanoma metastases. In vitro, untreated and LPS-treated murine and human BMSC-conditioned medium (CM) increased VCAM-1-dependent BMSC adherence and proliferation of B16M and A375M cells, respectively, as compared to basal medium-treated melanoma cells. Addition of celecoxib to both B16M and A375M cells abolished adhesion and proliferation increments induced by BMSC-CM. TNF alpha and VEGF secretion increased in the supernatant of LPS-treated BMSCs; however, anti-VEGF neutralizing antibodies added to B16M and A375M cells prior to LPS-treated BMSC-CM resulted in a complete abrogation of both adhesion-and proliferation-stimulating effect of BMSC on melanoma cells. Conversely, recombinant VEGF increased adherence to BMSC and proliferation of both B16M and A375M cells, compared to basal medium-treated cells, while addition of celecoxib neutralized VEGF effects on melanoma. Recombinant TNFa induced B16M production of VEGF via COX-2-dependent mechanism. Moreover, exogenous PGE2 also increased B16M cell adhesion to immobilized recombinant VCAM-1. Conclusions: We demonstrate the contribution of VEGF-induced tumor COX-2 to the regulation of adhesion-and proliferation-stimulating effects of TNFa, from endotoxin-activated bone marrow stromal cells, on VLA-4-expressing
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28 p.
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晶界结构在高温下的热稳定性问题是一个长期争论而又未能解决的问题,其争论的焦点是:在远低于熔点的温度下,晶界结构是否发生了可观察到的无序化,即是否存在一个远低于熔点的结构转化温度。为了能澄清这一争论,本文系统地研究了晶界结构的热稳定性。为了消除相互作用势的影响和系统误差,本文首先采用Morse势和经验多体势分别对铝、铜单晶的熔化过程进行了分子动力学模拟。在平衡态下,通过计算表征结构无序化的静态结构因子、径向分布函数和单晶原子位形图,获得了铝、铜单晶的熔点,结果表明:多体势计算的铝和铜的单晶熔点更接近实验值。因此,采用经验多体势应用分子动力学方法分别模拟了铝、铜Σ3、Σ5、Σ9、Σ11、Σ19、Σ33六种对称倾侧双晶晶界晶界结构由有序向无序转化的过程,计算了平衡态下的表征结构无序化的静态结构因子、径向分布函数和晶界原子位形图并将多体势获得的铝、铜单晶熔点作为晶界结构转化温度的约化熔点,获得了铝、铜Σ3、Σ5、Σ9、Σ11、Σ19、Σ33六种对称倾侧双晶晶界结构的转化温度和熔点,结果表明:1.Σ5、Σ9、Σ11、Σ19、Σ33五种对称倾侧双晶晶界均在远低于单晶熔点温度时,晶界结构发生了可观察到的无序化,而且双晶晶界结构的转变温度相差不大,双晶晶界熔点也低于单晶熔点。2.Σ3晶界在温度远低于熔点时,其晶界结构没有发生可观察到的无序化;Σ3晶界的转化温度与单晶熔点接近。所以,可以认为Σ3晶界不存在转化温度。这是由于Σ3晶界为共格孪晶,具有较低的能量。综上所述,除Σ3共格孪晶外,在远低于熔点温度下,晶界结构发生了可观察到的无序化,即:存在一个远低于熔点的转化温度,此时其静态结构因子约为0.5左右;晶界结构的熔点均低于单晶熔点,此时其静态结构因子约为0.15左右。从全文模拟结果可以看出,静态结构因子、径向分布函数、晶界原子位形图三种方法在确定晶界的结构转化温度和熔点时,静态结构因子是最有效、最准确的定量方法。
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A study was embarked upon with the twin objectives of reviewing the Green Revolution Strategy for accelerating fish production in the country and proposing an alternative strategy, a private sector approach. Some of the programmes listed in the Green Revolution are very necessary for developing a viable - fish farming industry and that money spent under such programmes is money well spent. Programmes that are also desirable but need to be considerably expanded were identified. Other programmes have been criticised on the grounds that the method chosen to achieve the desired objectives is fraught with dangers if sufficiently long run view of fisheries development is taken
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Background: The aim of this study is to examine the influence of the catechol-O-methyltranferase (COMT) gene (polymorphism Val158 Met) as a risk factor for Alzheimer's disease (AD) and mild cognitive impairment of amnesic type (MCI), and its synergistic effect with the apolipoprotein E gene (APOE). A total of 223 MCI patients, 345 AD and 253 healthy controls were analyzed. Clinical criteria and neuropsychological tests were used to establish diagnostic groups. The DNA Bank of the University of the Basque Country (UPV-EHU) (Spain) determined COMT Val158 Met and APOE genotypes using real time polymerase chain reaction (rtPCR) and polymerase chain reaction (PCR), and restriction fragment length polymorphism (RFLPs), respectively. Multinomial logistic regression models were used to determine the risk of AD and MCI. Results: Neither COMT alleles nor genotypes were independent risk factors for AD or MCI. The high activity genotypes (GG and AG) showed a synergistic effect with APOE epsilon 4 allele, increasing the risk of AD (OR = 5.96, 95% CI 2.74-12.94, p < 0.001 and OR = 6.71, 95% CI 3.36-13.41, p < 0.001 respectivily). In AD patients this effect was greater in women. In MCI patients such as synergistic effect was only found between AG and APOE epsilon 4 allele (OR = 3.21 95% CI 1.56-6.63, p = 0.02) and was greater in men (OR = 5.88 95% CI 1.69-20.42, p < 0.01). Conclusion: COMT (Val158 Met) polymorphism is not an independent risk factor for AD or MCI, but shows a synergistic effect with APOE epsilon 4 allele that proves greater in women with AD.