999 resultados para From 1906 to 1957
Resumo:
A personal account of the establishment of luminescent PET (photoinduced electron transfer) sensing and its development into molecular logic is given. Several applications of these two research areas, e.g. blood electrolyte diagnostics, ‘lab-on-amolecule’ systems and molecular computational identification (MCID) are illustrated.
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The cysteine cathepsins are a family of closely related thiol proteases, normally found in the endosomal and lysosomal compartments of cells. A growing body of evidence has clearly linked the dysregulated activity of these proteases with many diseases and pathological conditions, offering therapeutic, prognostic and diagnostic potential. However, these proteases are synthesised as inactive precursors and once activated, are controlled by factors such as pH and presence of endogenous inhibitors, meaning that overall protein and activity levels do not necessarily correlate. In order to fully appreciate the role and potential of these proteases, tools are required that can detect and quantify overall cathepsin activity. Two main strategies have evolved; synthetic substrates and protease-labelling with affinity-binding probes (or activity-based probes). This review examines recent innovations in these approaches as the field moves towards developing tools that could ultimately be used in patients for diagnostic or prognostic applications.
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Alkali activated binders, based on ash and slag, also known as geopolymers, can play a key role in reducing the carbon footprint of the construction sector by replacing ordinary Portland cement in some concretes. Since 1970s, research effort has been ongoing in many research institutions. In this study, pulverized fuel ash (pfa) from a UK power plant, ground granulated blast furnace slag (ggbs) and combinations of the two have been investigated as geopolymer binders for concrete applications. Activators used were sodium hydroxide and sodium silicate solutions. Mortars with sand/binder ratio of 2.75 with several pfa and ggbs combinations have been mixed and tested. The optimization of alkali dosage (defined as the Na2O/binder mass ratio) and modulus (defined as the Na2O/SiO2 mass ratio) resulted in strengths in excess of 70 MPa for tested mortars. Setting time and workability have been considered for the identification of the best combination of pfa/ggbs and alkali activator dosage for different precast concrete products. Geopolymer concrete building blocks have been replicated in laboratory and a real scale factory trial has been successfully carried out. Ongoing microstructural characterization is aiming to identify reaction products arising from pfa/ggbs combinations.
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Risk is the dominant frame for the European Union’s growing albeit often overlooked public health governance. The starting point for this chapter is the distortion of public health priorities by and within this frame. I argue that existing efforts to identify, underline and tackle the distortions can be strengthened by reframing governance as a matter of citizenship so as to develop citizen participation in decision making.
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The need for companies to consider the environmental impact of their operations and supply chains has been highlighted in the literature. However, few studies appear to consider how companies’ progress from proactive environmental strategies implemented at the internal, operations level to proactive environmental strategies implemented at the supply chain level. This study assesses the implementation process through the lens of the natural resource-based view and dynamic capabilities perspective. First, the link between the internal strategy ‘pollution prevention’ and the supply chain strategy ‘process stewardship’ is assessed. Second, the mediating influence of the internal support processes ‘integration’ and ‘learning’ on the implementation process is considered. Data collected from a sample of 1200 UK-based food manufacturing companies is analysed using multiple regression analysis. The findings suggest that the progression to environmental efforts at the supply chain level begins with internally-based environmental efforts and that the integration of these efforts and experience gained from them are important supporting factors in this progression.
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Absolute photoionization cross-section calculations are presented for Se + using large-scale close-coupling calculations within the Breit--Pauli and Dirac--Coulomb R -matrix approximations. The results from our theoretical work are compared with recent measurements (Esteves 2010 PhD Thesis publication number AAI3404727, University of Reno, NV, USA; Sterling et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 025701; Esteves et al 2011 Phys. Rev. A 84 013406) made at the advanced light source (ALS) radiation facility in Berkeley, CA, USA. We report on results for the photon energy range 18.0--31.0 eV, which spans the ionization thresholds of the 4 S o 3/2 ground state and the low-lying 2 D o 5/2,3/2 and 2 P o 3/2,1/2 metastable states. Metastable fractions are inferred from our present work. Resonance energies and quantum defects of the prominent Rydberg resonances series identified in the spectra are compared for the 4p → n d transitions with the recent ALS experimental measurements made on this complex trans-iron element.
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Background: Underweight and severe and morbid obesity are associated with highly elevated risks of adverse health outcomes. We estimated trends in mean body-mass index (BMI), which characterises its population distribution, and in the prevalences of a complete set of BMI categories for adults in all countries.
Methods: We analysed, with use of a consistent protocol, population-based studies that had measured height and weight in adults aged 18 years and older. We applied a Bayesian hierarchical model to these data to estimate trends from 1975 to 2014 in mean BMI and in the prevalences of BMI categories (<18·5 kg/m2 [underweight], 18·5 kg/m2 to <20 kg/m2, 20 kg/m2 to <25 kg/m2, 25 kg/m2 to <30 kg/m2, 30 kg/m2 to <35 kg/m2, 35 kg/m2 to <40 kg/m2, ≥40 kg/m2 [morbid obesity]), by sex in 200 countries and territories, organised in 21 regions. We calculated the posterior probability of meeting the target of halting by 2025 the rise in obesity at its 2010 levels, if post-2000 trends continue.
Findings: We used 1698 population-based data sources, with more than 19·2 million adult participants (9·9 million men and 9·3 million women) in 186 of 200 countries for which estimates were made. Global age-standardised mean BMI increased from 21·7 kg/m2 (95% credible interval 21·3–22·1) in 1975 to 24·2 kg/m2 (24·0–24·4) in 2014 in men, and from 22·1 kg/m2 (21·7–22·5) in 1975 to 24·4 kg/m2 (24·2–24·6) in 2014 in women. Regional mean BMIs in 2014 for men ranged from 21·4 kg/m2 in central Africa and south Asia to 29·2 kg/m2 (28·6–29·8) in Polynesia and Micronesia; for women the range was from 21·8 kg/m2 (21·4–22·3) in south Asia to 32·2 kg/m2 (31·5–32·8) in Polynesia and Micronesia. Over these four decades, age-standardised global prevalence of underweight decreased from 13·8% (10·5–17·4) to 8·8% (7·4–10·3) in men and from 14·6% (11·6–17·9) to 9·7% (8·3–11·1) in women. South Asia had the highest prevalence of underweight in 2014, 23·4% (17·8–29·2) in men and 24·0% (18·9–29·3) in women. Age-standardised prevalence of obesity increased from 3·2% (2·4–4·1) in 1975 to 10·8% (9·7–12·0) in 2014 in men, and from 6·4% (5·1–7·8) to 14·9% (13·6–16·1) in women. 2·3% (2·0–2·7) of the world's men and 5·0% (4·4–5·6) of women were severely obese (ie, have BMI ≥35 kg/m2). Globally, prevalence of morbid obesity was 0·64% (0·46–0·86) in men and 1·6% (1·3–1·9) in women.
Interpretation: If post-2000 trends continue, the probability of meeting the global obesity target is virtually zero. Rather, if these trends continue, by 2025, global obesity prevalence will reach 18% in men and surpass 21% in women; severe obesity will surpass 6% in men and 9% in women. Nonetheless, underweight remains prevalent in the world's poorest regions, especially in south Asia.
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Patients often spend time as inpatients in hospitals outside their home area because of the need to access specialist services. If there is a need for ongoing care after the need for specialist care has passed, patients are transferred (or ‘repatriated’) back to the inpatient care of a hospital in their local Health and Social Care Trust. The need for bed space in specialist units means that there is pressure for this transition to occur in a timely way. We investigated the flow of patients through a trauma and orthopaedics unit using the 6M Design® framework and Vitals Charts® in order to investigate concerns about delayed repatriation. We found that repatriation was part of a complex system that had interdependent components. There was considerable variation in the number of discharges (to any destination) by day of week, with a reduction on Saturdays and Sundays. Understanding that the pressure for quicker repatriation was really due to high work-in-progress led us to model the effects of strategies to address the high work-in-progress. We found that, because only a small proportion of patients require repatriation, expediting the repatriation process by one day for each patient would only reduce WIP by an average of 1.6 patients. Reducing the average length of stay for all trauma and orthopaedics inpatients by one day would reduce the WIP by 10 patients, which would make a much greater impact on the problem of high bed occupancy. Though the smooth and timely repatriation of patients to rehabilitation units is desirable, it is unlikely that efforts to achieve this will have a substantial impact on the problem of high WIP, so other strategies will be required. We will model the effects of strategies to reduce variation in daily discharges by the day of week in a future essay.
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Nowadays, a systems biology approach is both a challenge as well as believed to be the ideal form of understanding the organisms’ mechanisms of response. Responses at different levels of biological organization should be integrated to better understand the mechanisms, and hence predict the effects of stress agents, usable in broader contexts. The main aim of this thesis was to evaluate the underlying mechanisms of Enchytraeus albidus responses to chemical stressors. Therefore, there was a large investment on the gene library enrichment for this species, as explained ahead. Overall, effects of chemicals from two different groups (metals and pesticides) were assessed at different levels of biological organization: from genes and biochemical biomarkers to population endpoints. Selected chemicals were: 1) the metals cadmium and zinc; 2) the insecticide dimethoate, the herbicide atrazine and the fungicide carbendazim. At the gene and sub-cellular level, the effects of time and dosage were also adressed. Traditional ecotoxicological tests - survival, reproduction and avoidance behavior - indicated that pesticides were more toxic than metals. Avoidance behaviour is extremely important from an ecological point of view, but not recommended to use for risk assessment purposes. The oxidative stress related experiment showed that metals induced significant effects on several antioxidant enzyme activities and substrate levels, as well as oxidative damage on the membrane cells. To increase the potential of our molecular tool to assess transcriptional responses, the existing cDNA library was enriched with metal and pesticide responding genes, using Suppression Subtractive Hybridization (SSH). With the sequencing information obtained, an improved Agilent custom oligonucleotide microarray was developed and an EST database, including all existing molecular data on E. albidus, was made publicly available as an interactive tool to access information. With this microarray tool, most interesting and novel information on the mechanisms of chemical toxicity was obtained, with the identification of common and specific key pathways affected by each compound. The obtained results allowed the identification of mechanisms of action for the tested compounds in E. albidus, some of which are in line with the ones known for mammals, suggesting across species conserved modes of action and underlining the usefulness of this soil invertebrate as a model species. In general, biochemical and molecular responses were influenced by time of exposure and chemical dosage and these allowed to see the evolution of events. Cellular energy allocation results confirmed the gene expression evidences of an increased energetic expenditure, which can partially explain the decrease on the reproductive output, verified at a later stage. Correlations found throughout this thesis between effects at the different levels of biological organization have further improved our knowledge on the toxicity of metals and pesticides in this species.