Available Databases (available + databases)

Distribution by Scientific Domains


Selected Abstracts


Thermodynamic analysis of two-step solar water splitting with mixed iron oxides

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2009
Martin Roeb
Abstract A two-step thermochemical cycle for solar production of hydrogen from water has been developed and investigated. It is based on metal oxide redox pair systems, which can split water molecules by abstracting oxygen atoms and reversibly incorporating them into their lattice. After successful experimental demonstration of several cycles of alternating hydrogen and oxygen production, the present work describes a thermodynamic study aiming at the improvement of process conditions and at the evaluation of the theoretical potential of the process. In order to evaluate the maximum hydrogen production potential of a coating material, theoretical considerations based on thermodynamic laws and properties are useful and faster than actual tests. Through thermodynamic calculations it is possible to predict the theoretical maximum output of H2 from a specific redox-material under certain conditions. Calculations were focussed on the two mixed iron oxides nickel,iron-oxide and zinc,iron-oxide. In the simulation the amount of oxygen in the redox-material is calculated before and after the water-splitting step on the basis of laws of thermodynamics and available material properties for the chosen mixed iron oxides. For the simulation the commercial Software FactSage and available databases for the required material properties were used. The analysis showed that a maximum hydrogen yield is achieved if the reduction temperature is raised to the limits of the operation range, if the temperature for the water splitting is lowered below 800°C and if the partial pressure of oxygen during reduction is decreased to the lower limits of the operational range. The predicted effects of reduction temperature and partial pressure of oxygen could be confirmed in experimental studies. The increased hydrogen yield at lower splitting temperatures of about 800°C could not be confirmed in experimental results, where a higher splitting temperature led to a higher hydrogen yield. As a consequence it can be stated that kinetics must play an important role especially in the splitting step. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Effectiveness of interventions that assist caregivers to support people with dementia living in the community: a systematic review

INTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 2 2008
Deborah Parker BA, MSocSci
Executive summary Objectives, The objective of this review was to assess the effectiveness of interventions that assist caregivers to provide support for people living with dementia in the community. Inclusion criteria, Types of participants, Adult caregivers who provide support for people with dementia living in the community (non-institutional care). Types of interventions, Interventions designed to support caregivers in their role such as skills training, education to assist in caring for a person living with dementia and support groups/programs. Interventions of formal approaches to care designed to support caregivers in their role, care planning, case management and specially designated members of the healthcare team , for example dementia nurse specialist or volunteers trained in caring for someone with dementia. Types of studies, This review considered any meta-analyses, systematic reviews, randomised control trials, quasi-experimental studies, cohort studies, case control studies and observational studies without control groups that addressed the effectiveness of interventions that assist caregivers to provide support for people living with dementia in the community. Search strategy, The search sought to identify published studies from 2000 to 2005 through the use of electronic databases. Only studies in English were considered for inclusion. The initial search was conducted of the databases, CINAHL, MEDLINE and PsychINFO using search strategies adapted from the Cochrane Dementia and Cognitive Improvement Group. A second more extensive search was then conducted using the appropriate Medical Subject Headings (MeSH) and keywords for other available databases. Finally, hand searching of reference lists of articles retrieved and of core dementia, geriatric and psycho geriatric journals was undertaken. Assessment of quality, Methodological quality of each of the articles was assessed by two independent reviewers using appraisal checklist developed by the Joanna Briggs Institute and based on the work of the Cochrane Collaboration and Centre for Reviews and Dissemination. Data collection and analysis, Standardised mean differences or weighted mean differences and their 95% confidence intervals were calculated for each included study reported in the meta-analysis. Results from comparable groups of studies were pooled in statistical meta-analysis using Review Manager Software from the Cochrane Collaboration. Heterogeneity between combined studies was tested using standard chi-square test. Where statistical pooling was not appropriate or possible, the findings are summarised in narrative form. Results, A comprehensive search of relevant databases, hand searching and cross referencing found 685 articles that were assessed for relevance to the review. Eighty-five papers appeared to meet the inclusion criteria based on title and abstract, and the full paper was retrieved. Of the 85 full papers reviewed, 40 were accepted for inclusion, three were systematic reviews, three were meta-analysis, and the remaining 34 were randomised controlled trials. For the randomised controlled trials that were able to be included in a meta-analysis, standardised mean differences or weighted mean differences and their 95% confidence intervals were calculated for each. Results from comparable groups of studies were pooled in statistical meta-analysis using Review Manager Software and heterogeneity between combined studies was assessed by using the chi-square test. Where statistical pooling was not appropriate or possible, the findings are summarised in narrative form. The results are discussed in two main sections. Firstly it was possible to assess the effectiveness of different types of caregiver interventions on the outcome categories of depression, health, subjective well-being, self-efficacy and burden. Secondly, results are reported by main outcome category. For each of these sections, meta-analysis was conducted where it was possible; otherwise, a narrative summary describes the findings. Effectiveness of intervention type, Four categories of intervention were included in the review , psycho-educational, support, multi-component and other. Psycho-educational Thirteen studies used psycho-educational interventions, and all but one showed positive results across a range of outcomes. Eight studies were entered in a meta-analysis. No significant impact of psycho-educational interventions was found for the outcome categories of subjective well-being, self-efficacy or health. However, small but significant results were found for the categories of depression and burden. Support Seven studies discussed support only interventions and two of these showed significant results. These two studies were suitable for meta-analysis and demonstrated a small but significant improvement on caregiver burden. Multi-component Twelve of the studies report multi-component interventions and 10 of these report significant outcomes across a broad range of outcome measures including self-efficacy, depression, subjective well-being and burden. Unfortunately because of the heterogeneity of study designs and outcome measures, no meta-analysis was possible. Other interventions Other interventions included the use of exercise or nutrition which resulted in improvements in psychological distress and health benefits. Case management and a computer aided support intervention provided mixed results. One cognitive behavioural therapy study reported a reduction in anxiety and positive impacts on patient behaviour. Effectiveness of interventions using specific outcome categories, In addition to analysis by type of intervention it was possible to analyse results based on some outcome categories that were used across the studies. In particular the impact of interventions on caregiver depression was available for meta-analysis from eight studies. This indicated that multi-component and psycho-educational interventions showed a small but significant positive effect on caregiver depression. Five studies using the outcome category of caregiver burden were entered into a meta-analysis and findings indicated that there were no significant effects of any of interventions. No meta-analysis was possible for the outcome categories of health, self-efficacy or subjective well-being. Implications for practice, From this review there is evidence to support the use of well-designed psycho-educational or multi-component interventions for caregivers of people with dementia who live in the community. Factors that appear to positively contribute to effective interventions are those which: ,,Provide opportunities within the intervention for the person with dementia as well as the caregiver to be involved ,,Encourage active participation in educational interventions for caregivers ,,Offer individualised programs rather than group sessions ,,Provide information on an ongoing basis, with specific information about services and coaching regarding their new role ,,Target the care recipient particularly by reduction in behaviours Factors which do not appear to have benefit in interventions are those which: ,,Simply refer caregivers to support groups ,,Only provide self help materials ,,Only offer peer support [source]


Proteomic identification of biomarkers related to Helicobacter pylori -associated gastroduodenal disease: Challenges and opportunities

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 11 2008
Ming-Shiang Wu
Abstract Helicobacter pylori colonize the stomach of over half the world's population. While 80,90% H. pylori -infected individuals have clinically asymptomatic gastritis, 10,15% develop peptic ulcer, and 1,2% gastric malignancies. These variable clinical outcomes have led to an interest in prognostic indicators. The current disease paradigm suggests that host genetics and bacterial virulence both play important roles in modulating the final outcome of H. pylori infection. Elucidation of the interaction between host and bacterium is essential to clarify pathogenesis and to develop new strategies for prevention and treatment. Proteomic technology is a powerful tool for simultaneously monitoring proteins and protein variation on a large scale in biological samples. It has provided an unprecedented opportunity to survey a cell's translational landscape comprehensively, and the results may allow in-depth analyses of host and pathogen interactions. Using this high-throughput platform and taking advantage of complete sequences for both the H. pylori and the human genome in available databases, we have identified several crucial proteins that have pathogenic and prognostic potential. Among them, antibodies to AhpC and GroEs of H. pylori could be utilized for identification of patients who are at high risk of disease complications after H. pylori infection. Evolving proteomic technologies, together with appropriate clinical phenotyping and genotype information should enhance understanding of disease pathogenesis and lead to more precise prediction of variable disease outcomes. It will also facilitate development of biomarkers for diagnosis, treatment, and prevention of H. pylori infection. [source]


Knowledge translation: An opportunity to reduce global health inequalities

JOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 8 2009
Vivian Welch
Abstract Knowledge translation represents an opportunity to redress global health inequalities. This paper first assesses models for how health inequalities are produced and sustained, including effects of catastrophic illness and globalisation. Secondly, this paper illustrates how methods for knowledge translation can be applied to reducing inequalities in health by ensuring the best evidence is applied when appropriate. Thirdly, the paper describes available databases and tools for monitoring effects of knowledge translation on global health inequalities. In particular, mapping methods for creating visual representations of changes in global health inequalities are useful for setting priorities for action and research. Copyright © 2009 John Wiley & Sons, Ltd. [source]


New technique for in-situ measurement of backscattered and secondary electron yields for the calculation of signal-to-noise ratio in a SEM

JOURNAL OF MICROSCOPY, Issue 3 2005
K. S. SIM
Summary The quality of an image generated by a scanning electron microscope is dependent on secondary emission, which is a strong function of surface condition. Thus, empirical formulae and available databases are unable to take into account actual metrology conditions. This paper introduces a simple and reliable measurement technique to measure secondary electron yield (,) and backscattered electron yield (,) that is suitable for in-situ measurements on a specimen immediately prior to imaging. The reliability of this technique is validated on a number of homogenous surfaces. The measured electron yields are shown to be within the range of published data and the calculated signal-to-noise ratio compares favourably with that estimated from the image. [source]


Review article: management of patients with chronic hepatitis C virus infection and ,normal' alanine aminotransferase activity

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2006
S. ZEUZEM
Summary Background Hepatitis C virus infection, a major cause of chronic liver disease, occurs with normal serum alanine aminotransferase activity in approximately 25% of patients. These patients have historically remained untreated but substantial evidence indicates liver damage, progression of disease and impaired quality of life in some individuals. Aim To review the current management of patients with chronic hepatitis C and normal alanine aminotransferase activity. Methods This review represents the summary of discussions at a Clinical Workshop with a comprehensive literature searching of available databases (PubMed and Embase). Results Current limits defining normal serum alanine aminotransferase activity are not representative of a ,healthy' status. Most patients with hepatitis C and normal alanine aminotransferase levels have histologically proven liver damage that, although generally mild, may be significant (,F2) in up to 20% of patients and progresses at approximately 50% of the rate in patients with elevated alanine aminotransferase levels. Some patients have persistently normal alanine aminotransferase activity and may have a more benign outcome, but a significant proportion (,20%) experience periods of increased serum alanine aminotransferase activity which may be associated with enhanced disease progression. Conclusions A treatment approach that considers host and virus-related variables and optimizes patient and cost benefits may therefore provide more effective management of patients with chronic hepatitis C and normal alanine aminotransferase activity. [source]


Challenges in Establishing the Epidemiology of Adverse Events Associated with Interventional Therapies for Chronic Pain

PAIN MEDICINE, Issue S1 2008
Timothy R. Deer MD
ABSTRACT Objectives., This paper aims to examine the current state of knowledge about adverse events associated with interventional pain techniques. Methods., This paper reviews the available databases on risk from sources such as closed claim analysis, peer review, and published literature; and also examines risk stratification for pain practitioners, the current state of malpractice insurance, and the procedures that are considered to have elevated risk. Conclusions., Substantial neurological sequelae can occur from interventional pain techniques. Considering the growing number of physicians who perform these procedures the actual occurrence of these problems appears to be low. The incidences of complications are difficult to correctly identify based on limitations of reporting and data analysis. The author recommends a national data bank be created to allow better monitoring and self assessment of the specialty of pain medicine. This information could be used to improve outcomes, reduce risk, and change clinical practice. [source]


The prenatal multiplier method for prediction of limb length discrepancy

PRENATAL DIAGNOSIS, Issue 6 2005
Jonathan Paley
Abstract Objective The purpose of this study was to produce a method of predicting limb length discrepancy in utero. Methods Using available databases, we divided the femoral and tibial lengths at term by the femoral and tibial lengths at each week of gestation for each percentile. The quotients represent coefficients (multipliers) of limb segment growth at each prenatal age. Results We found the prenatal multipliers to be independent of race, percentile, and gender from as early as 12 weeks' gestation. The prenatal multipliers are alike for femur and tibia. Conclusions The prenatal multiplier method allows for quick prediction of limb length discrepancy at term and at skeletal maturity from as early as 12 weeks' gestation. Future study is needed to validate this method clinically. Copyright © 2005 John Wiley & Sons, Ltd. [source]


PEAKS: powerful software for peptide de novo sequencing by tandem mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2003
Bin Ma
A number of different approaches have been described to identify proteins from tandem mass spectrometry (MS/MS) data. The most common approaches rely on the available databases to match experimental MS/MS data. These methods suffer from several drawbacks and cannot be used for the identification of proteins from unknown genomes. In this communication, we describe a new de novo sequencing software package, PEAKS, to extract amino acid sequence information without the use of databases. PEAKS uses a new model and a new algorithm to efficiently compute the best peptide sequences whose fragment ions can best interpret the peaks in the MS/MS spectrum. The output of the software gives amino acid sequences with confidence scores for the entire sequences, as well as an additional novel positional scoring scheme for portions of the sequences. The performance of PEAKS is compared with Lutefisk, a well-known de novo sequencing software, using quadrupole-time-of-flight (Q-TOF) data obtained for several tryptic peptides from standard proteins. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Seed production in fens and fen meadows along a disturbance gradient

APPLIED VEGETATION SCIENCE, Issue 3 2009
A. Klimkowska
Abstract Question: The seed production in several wetland communities across Europe was investigated and differences in seed output in relation to disturbance intensity were tested. The relationship between the vegetation composition and the seed production profile was examined and the results are discussed in relation to restoration. Location: Poland, Germany and the Netherlands. Methods: The seed production in various plant communities was estimated, based on field counts. In addition, records from available databases were used for missing data. Multivariate methods were used to characterize the vegetation and seed production. Communities were grouped according to level of disturbance and tested for differences in seed production. Similarity between vegetation composition and seed profile was examined using the Sørensen index and Spearman correlation coefficient. Results: It was found that the seed production of the studied communities is large, variable and in general increasing with disturbance intensity. The estimated median seed production was ca. 24 × 103 seeds m,2 in fens, 167 × 103 in fen meadows and 556 × 103 seeds m,2 in degraded meadows. The majority of seeds was produced by just a few species. The similarity between the vegetation composition and the seed production profile was low (similarity 52%, correlation coefficient 0.42, P<0.05) and slightly increased with disturbance intensity. Conclusions: Increased disturbance enhances seed production at the community level. The composition of the vegetation is a poor predictor of the seed output. It is estimated that the number of seeds transferred with hay is much lower than the seed production in fens and fen meadows. [source]


WWWWhy does nature stutter?

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2001
A survey of strands of repeated amino acids
Human stuttering is a simple example of the repetition of sounds or symbols, sometimes associated with single letters, and may be used to illustrate the amazing repetition of amino acids (symbolized by a letter, e.g. W) in proteins. A survey of available databases with highly improbable strings of single amino acids is tabulated. This paper concludes with a challenge to the crystallographic community to probe the structural origins of the structure,function relationship in this neglected area. When nature stutters, we should pay attention. [source]