904 resultados para prolonging of lifetime


Relevância:

80.00% 80.00%

Publicador:

Resumo:

Problem Queensland has the highest rates of skin cancer in the world, even after wide-ranging public programs promoting sun safety awareness. To-date, public awareness campaigns on the dangers of excessive sun exposure have been highly successful. For adolescents, however, where a significant amount of lifetime sun exposure occurs, perilous exposure still ensues, despite awareness of the risks. New frontier approaches are required to target this key audience cluster, for this significant national problem. Approach For the majority of adolescents, being part of a collective norm defines their visual, attitudinal and behavioural actions and fashion has been validated as one of the most powerful forces that can form, shape and bolster these norms. Considering clothing is the easiest method to limit the amount of skin exposed to UV, fashion (in its many subtle, yet influential guises) is proposed as an avenue to advance positive sun safe practices for adolescents. Through an action-led methodology, this research explores the potential of fashion, as one of the key parts of a complex equation, to be a prime driver to facilitate sun safety for adolescents. Findings This paper advocates that fashion, as distinguishable from clothing, has the potential to positively influence sun protective behaviour. The findings go further and recommend the use of fashion as a stealth driver for sun safety advancement, for adolescents in particular, via shifts in norms of beauty and targeted generational communication strategies. This frontier approach has the potential to significantly reduce risky sun exposure in adolescence.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

PIP: A delphi study was conducted to identify or envision health scenarios in India by the year 2000. Questionnaires consisting of 48 questions on 5 areas (diagnosis and therapy; family planning; pharmaceuticals and drugs; biochemical and biomedical research; health services) were mailed to 250 experts in India. 36 responded. Results were compiled and mailed back to the respondents for changes and comments. 17 people responded. Results of the delphi study shows that policy decisions with respect to compulsory family planning as well as health education at secondary school level will precede further breakthroughs in birth control technology. Non operation reversible sterilization procedures, immunological birth control, Ayurvedic medicines for contraception and abortion, and selection of baby's sex are all possible by 2000 thereafter. Complete eradication of infectious diseases, malnutrition and associated diseases is considered unlikely before 2000, as are advances in biomedical research. Changes in health services (e.g., significant increases in hospital beds and doctors, cheap bulk drugs), particularly in rural areas, are imminent, leading to prolonging of life expectancy to 70 years. Genetic engineering may provide significant breakthroughs in the prevention of malignancies and cardiac disorders. The India delphi study is patterned after a similar delphi study conducted in the U.S. by Smith, Kline and French (SKF) Laboratories in 1968. The SKF study was able to predict some breakthroughs with basic research which have been realized.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Most studies of life history evolution are based on the assumption that species exist at equilibrium and spatially distinct separated populations. In reality, this is rarely the case, as populations are often spatially structured with ephemeral local populations. Therefore, the characteristics of metapopulations should be considered while studying factors affecting life history evolution. Theoretical studies have examined spatial processes shaping the evolution of life history traits to some extent, but there is little empirical data and evidence to investigate model predictions. In my thesis I have tried to bridge the gap between theoretical and empirical studies by using the well-known Glanville fritillary (Melitaea cinxia) metapopulation as a model system. The long-term persistence of classic metapopulations requires sufficient dispersal to establish new local populations to compensate for local extinctions. Previous studies on the Glanville fritillary have shown that females establishing new populations are not a random sample from the metapopulation, but they are in fact more dispersive than females in old populations. Many other life-history traits, such as body size, fecundity and lifespan, may be related to dispersal rate. Therefore, I examined a range of correlated traits for their evolutionary and ecological consequences. I was particularly interested in how the traits vary under natural environmental conditions, hence all studies were conducted in a large (32 x 26 m) outdoor population cage built upon a natural habitat patch. Individuals for the experiments were sampled from newly-established and old populations within a large metapopulation. Results show that females originating from newly-established populations had higher within-habitat patch mobility than females from old populations. I showed that dispersal rate is heritable and that flight activity is related to variation in a gene encoding the glycolytic enzyme phosphoglucose isomerase. Both among-individual and among-population variation in dispersal are correlated with the reproductive performance of females, though I found no evidence for a trade-off between dispersal and fecundity in terms of lifetime egg production or clutch size. Instead, the results suggest that highly dispersive females from newly-established populations have a shorter lifespan than females from old populations, and that dispersive females may pay a cost in terms of reduced lifetime reproductive success due to increased time spent outside habitat patches. In summary, the results of this thesis show that genotype-dependent dispersal rate correlates with other life history traits in the Glanville fritillary, and that the rapid turnover of local populations (extinctions and re-colonisations) is likely to be the mechanism that maintains phenotypic variation in many life history traits at the metapopulation level.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The recombination properties of cobalt centers in p-type germanium containing cobalt in the concentration range 1014 to 1016 atoms/cm3 have been investigated. The measurement of lifetime has been carried out by steady-state photoconductivity and photo-magneto-electric methods in the temperature range 145 to 300°K. The cross-sections Sno (electron capture cross-section at neutral centers). Sn- (electron capture cross-section at singly negatively charged centers) and their temperature variations have been estimated by the analysis of the lifetime data on the basis of Sah-Shockley's multi-level formula. The value of Sno is (15±5).10-16 cm2 and is temperature independent. The value of Sn- is ≈4·10-16 cm2 around 225°K and it increases with increase of temperature. The possible mechanisms for capture at neutral and repulsive centers are discussed and a summary of the capture cross-sections for cobalt centers is given. A comparison of the cross-section values of cobalt and their temperature variations with those of the related impurities-manganese, iron and nickel-in germanium has been made.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Altruism is defined as any behaviour that lowers the Darwinian fitness of the actor while increasing that of the recipient. Such altruism (especially in the form of lifetime sterility exhibited by sterile workers in eusocial insects such as ants, bees, wasps and termites) has long been considered a major difficulty for the theory of natural selection. In the 1960s W. D. Hamilton potentially solved this problem by defining a new measure of fitness that he called inclusive fitness, which also included the effect of an individual's action on the fitness of genetic relatives. This has come to be known as inclusive fitness theory, Hamilton's rule or kin selection. E. O. Wilson almost single-handedly popularized this new approach in the 1970s and thus helped create a large body of new empirical research and a large community of behavioural ecologists and kin selectionists. Adding thrill and drama to our otherwise sombre lives, Wilson is now leading a frontal attack on Hamilton's approach, claiming that the inclusive fitness theory is not as mathematically general as the standard natural selection theory, has led to no additional biological insights and should therefore be abandoned. The world cannot but sit up and take notice.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Si bien la preocupación por la temporalidad no asume en Henri de Lubac un desarrollo sistemático, sin embargo es posible encontrarla como una temática subyacente y transversal en muchos de sus textos, relacionada estrechamente con la reflexión sobre el valor y el sentido de la historia. El autor propone indagar sobre el valor de lo temporal en la confrontación con las doctrinas del budismo, del humanismo ateo y de Joaquín de Fiore. El misterio del sobrenatural es la cuestión teológica elegida para exponer la respuesta y posición del teólogo francés en relación a la temporalidad. Finalmente la apertura de perspectivas críticas permitirá prolongar su pensamiento en preocupaciones actuales.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

methods of lifetime measurement are discussed.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

研究了退火和二次离子交换对Er^3+/Yb^3+共掺的磷酸盐玻璃平面光波导传输特性的影响。在退火过程中,由于热效应和波导层Ag^+离子的浓度差使得Ag^+离子重新分布;随着退火时间的延长和温度的升高,光波导模式数目逐渐增加,波导层深度加深,且波导表面折射率与玻璃基质折射率差减小,退火扩散深度与退火时间的平方根成正比。电子探针结果显示在二次离子交换后形成了掩埋式的光波导,Ag^+离子浓度接近二次方分布,而掩埋式的光波导有助于降低光波导的传输损耗。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

由溶胶一凝胶/燃烧合成结合法合成了Nd:YAG(掺钕钇铝石榴石,neodymium—doped yttrium aluminium garnet)粉体,用真空烧结法制备了Nd:YAG透明陶瓷。研究了显微结构随烧结温度和保温时间的变化,并对透明陶瓷的晶界结构和成分分布进行了表征。随着烧结温度的提高和保温时间的延长,Nd:YAG陶瓷的密度增大,晶形发育完整,透过率提高。晶粒内部和晶界的化学组成基本相同。所制备的Nd:YAG透明陶瓷在激光工作波长1064nm的透过率达到75%。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

束流储存寿命对于储存环的建造和内靶实验都是一个很重要的参数。由于重离子冷却储存环工程的优化,HIRFL-CSR主环将能提供2.SGev的质子束流,这为强子物理研究提供了一个很好的平台。设计并建立一套针对强子物理的内靶系统己经列入到计划当中,与内靶相关的束流储存寿命研究也随之展开。本论文首先分析了在内靶实验中束流储存寿命的影响因素,即真空管道中的残余气体分子、冷却电子束和内靶,以及束内散射和集体效应等,并用理论解析和数值计算的方法,对各种因素的影响程度进行估算。研究表明,内靶散射影响下的束流储存寿命比其他因素导致的短2~3个数量级,内靶是影响束流寿命的决定性因素。其次,对CSRm将来实验中主要用到的Pelle七内靶和碳薄膜靶做了简要介绍,并计算了它们的有效靶厚大约为lx10、切ms/cmZ和5火1017atoms/CmZ。再者,用理论推导方法,对内靶的多次库仑散射和束流能量损失扰动对束流的影响进行了研究,推导了束流的横向和纵向发射度增长与束流每次打靶产生的小库仑散射角均方值气s和相对动量分散气了:之间的关系,并通过数值计算的方法给出了CSRm内靶实验条件的发射度增长曲线。最后,建立了内靶散射的MOnte-Carlo模拟程序,在模拟数据的基础上,总结研究束流的发射度增长规律,以及束流存储寿命与内靶厚度和束流能量的关系。计算表明,当存在Pellet靶(1、1016atoms/cm2)和c膜(5*1017 atoms/cmZ)时,2800Mev质子束的束流储存寿命分别为397秒和0.7秒,将来的内靶实验亮度大约为2 x 1033cm-2·s-1。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The thesis initially gives an overview of the wave industry and the current state of some of the leading technologies as well as the energy storage systems that are inherently part of the power take-off mechanism. The benefits of electrical energy storage systems for wave energy converters are then outlined as well as the key parameters required from them. The options for storage systems are investigated and the reasons for examining supercapacitors and lithium-ion batteries in more detail are shown. The thesis then focusses on a particular type of offshore wave energy converter in its analysis, the backward bent duct buoy employing a Wells turbine. Variable speed strategies from the research literature which make use of the energy stored in the turbine inertia are examined for this system, and based on this analysis an appropriate scheme is selected. A supercapacitor power smoothing approach is presented in conjunction with the variable speed strategy. As long component lifetime is a requirement for offshore wave energy converters, a computer-controlled test rig has been built to validate supercapacitor lifetimes to manufacturer’s specifications. The test rig is also utilised to determine the effect of temperature on supercapacitors, and determine application lifetime. Cycle testing is carried out on individual supercapacitors at room temperature, and also at rated temperature utilising a thermal chamber and equipment programmed through the general purpose interface bus by Matlab. Application testing is carried out using time-compressed scaled-power profiles from the model to allow a comparison of lifetime degradation. Further applications of supercapacitors in offshore wave energy converters are then explored. These include start-up of the non-self-starting Wells turbine, and low-voltage ride-through examined to the limits specified in the Irish grid code for wind turbines. These applications are investigated with a more complete model of the system that includes a detailed back-to-back converter coupling a permanent magnet synchronous generator to the grid. Supercapacitors have been utilised in combination with battery systems for many applications to aid with peak power requirements and have been shown to improve the performance of these energy storage systems. The design, implementation, and construction of coupling a 5 kW h lithium-ion battery to a microgrid are described. The high voltage battery employed a continuous power rating of 10 kW and was designed for the future EV market with a controller area network interface. This build gives a general insight to some of the engineering, planning, safety, and cost requirements of implementing a high power energy storage system near or on an offshore device for interface to a microgrid or grid.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This paper describes a framework that is being developed for the prediction and analysis of electronics power module reliability both for qualification testing and in-service lifetime prediction. Physics of failure (PoF) reliability methodology using multi-physics high-fidelity and reduced order computer modelling, as well as numerical optimization techniques, are integrated in a dedicated computer modelling environment to meet the needs of the power module designers and manufacturers as well as end-users for both design and maintenance purposes. An example of lifetime prediction for a power module solder interconnect structure is described. Another example is the lifetime prediction of a power module for a railway traction control application. Also in the paper a combined physics of failure and data trending prognostic methodology for the health monitoring of power modules is discussed.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Objective: A history of childhood trauma is common in individuals who later develop psychosis. Similar neuroanatomical abnormalities are observed in people who have been exposed to childhood trauma and people with psychosis. However, the relationship between childhood trauma and such abnormalities in psychosis has not been investigated. This study aimed to explore the association between the experience of childhood trauma and hippocampal and amygdalar volumes in a first-episode psychosis (FEP) population. Methods: The study employed an observational retrospective design. Twenty-one individuals, who had previously undergone magnetic resonance imaging procedures as part of the longitudinal Northern Ireland First-Episode Psychosis Study, completed measures assessing traumatic experiences and were included in the analysis. Data were subject to correlation analyses (rand rob). Potential confounding variables (age at FEP and delay to scan from recruitment) were selected a priori for inclusion in multiple regression analyses. Results: There was a high prevalence of lifetime (95%) and childhood (76%) trauma in the sample. The experience of childhood trauma was a significant predictor of left hippocampal volume, although age at FEP also significantly contributed to this model. There was no significant association between predictor variables and right hippocampal volume. The experience of childhood trauma was a significant predictor of right and total amygdalar volumes and the hippocampal/amygdalar complex volume as a whole. Conclusions: The findings indicate that childhood trauma is associated with neuroanatomical measures in FEP. Future research controlling for childhood traumatic experiences may contribute to explaining brain morphology in people with psychosis.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Objectives. In a bipolar disorder (BD) sample, the present study investigated: (i) the prevalence of trauma; (ii) the specificity of autobiographical memory (AM); (iii) the influence of childhood trauma on AM specificity, current inter-episode depressive mood, and BD severity; (iv) if AM specificity moderates the influence of childhood trauma on current inter-episode depressive mood and BD severity.

Methods. Fifty-two participants were recruited from a geographically well-defined mental health service in Northern Ireland. The AM test, self-report measures of lifetime experience of trauma, childhood trauma, and depression were administered. Severity of BD was estimated utilizing a systematic tool for reviewing all available clinical data of participants.

Results. A high prevalence of trauma was found. A total of 94.2% (49/52) of participants reported experiencing a traumatic event in either childhood or adulthood. AM specificity was significantly lower than previous reports of such in major depression. However, whilst childhood trauma predicted current inter-episode depressive mood, childhood trauma was not predictive of BD severity or AM specificity. Moreover, the association between childhood trauma and depressed mood was not moderated by AM specificity.

Conclusions. The findings of this study suggest a relationship between early psychosocial adversity and current inter-episode depressive mood in BD. In addition, levels of overgeneral AM are similar to that reported for depression, but are unrelated to childhood trauma, current inter-episode depressive mood, or BD severity. Clinical implications include the importance of routine assessment of trauma in BD and the need for adjunctive evidenced-based psychological therapies.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Objectives: This study examined: (i) the prevalence of lifetime trauma, childhood trauma and trauma related to civil unrest in a Bipolar Disorder sample, and (ii) the agreement between rates of disclosure of trauma in case notes and self-report questionnaires.

Methods: The case notes of sixty participants, recruited from a geographically well-defined mental health service in Northern Ireland, were examined for reports of experiences of lifetime, childhood and traumatic events related to civil conflict. The participants also completed self-report measures of trauma.

Results: Considerable differences were found between the prevalence of trauma as measured by self-report questionnaires and case notes reports. The prevalence of lifetime trauma as measured by the Trauma History Questionnaire was 61.7% (compared to case notes prevalence of 33.3%). The prevalence of moderate and severe levels of childhood trauma as measured by the Childhood Trauma Questionnaire was 65% (case notes 21.7%). Rates of trauma related to civil unrest were 35% (case notes 3.3%). Poor levels of agreement were found between all self-report trauma measures and case notes reports. Agreement on two categories of trauma (childhood emotional neglect and childhood physical neglect) reached statistical significance but kappa scores suggest this agreement was poor (kappa = .14. p<.05; kappa = .127, p<.05). © 2011 Elsevier B.V. All rights reserved.

Conclusions: It is probable that the increased rate of trauma disclosed in the self-report questionnaire arises because clinicians during initial assessment and subsequent treatment do not consistently enquire about trauma. The need for staff training is discussed. (C) 2011 Elsevier B.V. All rights reserved.