27 resultados para Effective half-life


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Intracellular reactive oxygen species (ROS) production is essential to normal cell function. However, excessive ROS production causes oxidative damage and cell death. Many pharmacological compounds exert their effects on cell cycle progression by changing intracellular redox state and in many cases cause oxidative damage leading to drug cytotoxicity. Appropriate measurement of intracellular ROS levels during cell cycle progression is therefore crucial in understanding redox-regulation of cell function and drug toxicity and for the development of new drugs. However, due to the extremely short half-life of ROS, measuring the changes in intracellular ROS levels during a particular phase of cell cycle for drug intervention can be challenging. In this article, we have provided updated information on the rationale, the applications, the advantages and limitations of common methods for screening drug effects on intracellular ROS production linked to cell cycle study. Our aim is to facilitate biomedical scientists and researchers in the pharmaceutical industry in choosing or developing specific experimental regimens to suit their research needs.

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We have designed and implemented a low-cost digital system using closed-circuit television cameras coupled to a digital acquisition system for the recording of in vivo behavioral data in rodents and for allowing observation and recording of more than 10 animals simultaneously at a reduced cost, as compared with commercially available solutions. This system has been validated using two experimental rodent models: one involving chemically induced seizures and one assessing appetite and feeding. We present observational results showing comparable or improved levels of accuracy and observer consistency between this new system and traditional methods in these experimental models, discuss advantages of the presented system over conventional analog systems and commercially available digital systems, and propose possible extensions to the system and applications to nonrodent studies.

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This paper deals with second-generation, one-and-a-half generation and ‘‘prolonged sojourner” Trinidadian transnational migrants, who have decided to ‘return’ to the birthplace of their parents. Based on 40 in-depth interviews, the paper considers both the positive and critical things that these youthful transnational migrants report about returning to, and living in, this multi-ethnic plural society and the salience of racial and colour-class stratification as part of their return migration experiences. Our qualitative analysis is based on the narratives provided by these youthful returnees, as relayed ‘‘in their own words”, presenting critical reflections on racism, racial identities and experiences as transnational Trinidadians. It is clear that it is contexts such as contemporary working environments, family and community that act as the reference points for the adaptation ‘‘back home” of this strongly middle-class cohort. We accordingly encounter a diverse, sometimes contesting set of racial issues that emerge as salient concerns for these returnees. The consensus is that matters racial remain as formidable legacies in the hierarchical stratification of Trinidadian society for a sizeable number. Many of our respondents reported the positive aspects of racial affirmation on return. But for another sub-set, the fact that multi-ethnic and multi-cultural mixing are proudly embraced in Trinidad meant that it was felt that return experiences were not overly hindered, or blighted by obstacles of race and colour-class. For these returnees, Trinidad and Tobago is seen as representing a 21st century ‘‘Melting Pot”. But for others the continued existence of racial divisions within society – between ethnic groups and among those of different skin shades – was lamented. In the views of these respondents, too much racial power is still ascribed to ‘near-whiteness’. But for the most part, the returnees felt that where race played a part in their new lives, this generally served to advantage them. However, although the situation in Trinidad appears to have been moderated by assumptions that it remains a racial ‘Melting Pot’, the analysis strongly suggests that the colour-class system of stratification is still playing an essential role, along with racial stereotyping in society at large.

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The Species 2000 & ITIS Catalogue of Life is planned to become a comprehensive catalogue of all known species of organisms on Earth by the year 2011. Rapid progress has been made recently and this, the sixth edition of the Annual Checklist, contains 884,552 species, approximately half of all known organisms. The present Catalogue is compiled with sectors provided by 37 taxonomic databases from around the world. Many of these contain taxonomic data and opinions from extensive networks of specialists, so that the complete work contains contributions from an estimated 2-3,000 specialists from throughout the taxonomic profession. The work of the Species 2000 and ITIS teams is to peer review databases, select appropriate sectors and to integrate the sectors into a single coherent catalogue with a single hierarchical classification. It is planned in future to introduce alternative taxonomic treatments and alternative hierarchies, but an important feature is that for those users who wish to use it, a single preferred catalogue, based on peer reviews, will continue to be provided.

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The study investigated the relationship between depressive feelings and coping amongst older widowed men and women. Participants were interviewed about their affective experiences of widowhood and completed two depression questionnaire assessments, the Symptoms of Anxiety and Depression Scale ( SAD) and the Hospital Anxiety and Depression Scale ( HADS). Participants were assessed as either coping or not coping. The results showed that both measures were effective at differentiating those who coped (Copers) from those who did not (Non-Copers) in the sample as a whole. Amongst the widows the HADS significantly differentiated the two groups. Amongst men, neither measure significantly distinguished Copers from Non-Copers. However, an examination of the interviews suggested that widowers reported depressive feelings significantly more often than widows. The results suggest that depressive feelings are associated with non-coping in older widowed people. There is also evidence to suggest that widows and widowers respond differentially to assessment measures.

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There is potential to reduce both operational and embodied greenhouse gas emission from buildings. To date the focus has been on reducing the operational element, although given the urgency of carbon reductions, it may be more beneficial to consider upfront embodied carbon reductions. This paper describes a case study on the whole life carbon cycle of a warehouse building in Swindon, UK. It examines the relationship between embodied carbon (Ec) and operational carbon (Oc), the proportions of Ec from the structural and non-structural elements, carbon benchmarking of the structure, the value of ‘cradle to site’ or ‘cradle to grave’ assessments and the significance of the timing of emissions during the life of the building. The case study indicates that Ec was dominant for the building and that the structure was responsible for more than half of the Ec. Weighting of future emissions appears to be an important factor to consider. The PAS 2050 reduction factors had only a modest effect but weighting to allow for future decarbonisation of the national grid energy supply had a large effect. This suggests that future operational carbon emissions are being overestimated compared to embodied.

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The UK has adopted legally binding carbon reduction targets of 34% by 2020 and 80% by 2050 (measured against the 1990 baseline). Buildings are estimated to be responsible for more than 50% of greenhouse gas (GHG) emissions in the UK. These consist of both operational, produced during use, and embodied, produced during manufacture of materials and components, and during construction, refurbishments and demolition. A brief assessment suggests that it is unlikely that UK emission reduction targets can be met without substantial reductions in both Oc and Ec. Oc occurs over the lifetime of a building whereas the bulk of Ec occurs at the start of a building’s life. A time value for emissions could influence the decision making process when it comes to comparing mitigation measures which have benefits that occur at different times. An example might be the choice between building construction using low Ec construction materials versus building construction using high Ec construction materials but with lower Oc, although the use of high Ec materials does not necessarily imply a lower Oc. Particular time related issues examined here are: the urgency of the need to achieve large emissions reductions during the next 10 to 20 years; the earlier effective action is taken, the less costly it will be; future reduction in carbon intensity of energy supply; the carbon cycle and relationship between the release of GHG’s and their subsequent concentrations in the atmosphere. An equation is proposed, which weights emissions according to when they occur during the building life cycle, and which effectively increases Ec as a proportion of the total, suggesting that reducing Ec is likely to be more beneficial, in terms of climate change, for most new buildings. Thus, giving higher priority to Ec reductions is likely to result in a bigger positive impact on climate change and mitigation costs.

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Social anxiety disorder is one of the most persistent and common of the anxiety disorders, with lifetime prevalence rates in Europe of 6.7% (range 3.9-13.7%).1 It often coexists with depression, substance use disorder, generalised anxiety disorder, panic disorder, and post-traumatic stress disorder.2 It can severely impair a person’s daily functioning by impeding the formation of relationships, reducing quality of life, and negatively affecting performance at work or school. Despite this, and the fact that effective treatments exist, only about half of people with this condition seek treatment, many after waiting 10-15 years.3 Although about 40% of those who develop the condition in childhood or adolescence recover before adulthood,4 for many the disorder persists into adulthood, with the chance of spontaneous recovery then limited compared with other mental health problems. This article summarises the most recent recommendations from the National Institute for Health and Care Excellence (NICE) on recognising, assessing, and treating social anxiety disorder in children, young people, and adults.5

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The solution of an initial-boundary value problem for a linear evolution partial differential equation posed on the half-line can be represented in terms of an integral in the complex (spectral) plane. This representation is obtained by the unified transform introduced by Fokas in the 90's. On the other hand, it is known that many initial-boundary value problems can be solved via a classical transform pair, constructed via the spectral analysis of the associated spatial operator. For example, the Dirichlet problem for the heat equation can be solved by applying the Fourier sine transform pair. However, for many other initial-boundary value problems there is no suitable transform pair in the classical literature. Here we pose and answer two related questions: Given any well-posed initial-boundary value problem, does there exist a (non-classical) transform pair suitable for solving that problem? If so, can this transform pair be constructed via the spectral analysis of a differential operator? The answer to both of these questions is positive and given in terms of augmented eigenfunctions, a novel class of spectral functionals. These are eigenfunctions of a suitable differential operator in a certain generalised sense, they provide an effective spectral representation of the operator, and are associated with a transform pair suitable to solve the given initial-boundary value problem.

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This article examines republican arguments for a basic income that turn on a right to exit the labour market. It gives criteria for the maintenance of republican freedom in markets, arguing that a right to exit or effective market power will guarantee republican freedom in markets. The article then considers whether a basic income is either sufficient or necessary to protect republican freedom both in labour markets and elsewhere. If a basic income is necessary to protect republican freedom in the labour market, I argue it is not sufficient to protect that freedom elsewhere. If citizens lack the means to maintain their republican freedom in the labour market, then there may be other spheres of life where they are vulnerable to subordination, whether or not they have a basic income. Some sociological evidence on cultural consumption patterns is presented.