113 research outputs found
Unprecedented reductive cyclisation of salophen ligands to tetrahydroquinoxalines during metal complex formation
The synthesis of novel tetrahydroquinoxalines by a metal induced one–electron reductive cyclisation of salophen ligands was found to occur when a salophen ligand was treated with chromium(II) chloride or decamethylcobaltocen
Polarizing Grids, Their Assemblies and Beams of Radiation
This article gives an analysis of the behavior of polarizing grids and
reflecting polarizers by solving Maxwell's equations, for arbitrary angles of
incidence and grid rotation, for cases where the excitation is provided by an
incident plane wave or a beam of radiation. The scattering and impedance matrix
representations are derived and used to solve more complicated configurations
of grid assemblies. The results are also compared with data obtained in the
calibration of reflecting polarizers at the Owens Valley Radio Observatory
(OVRO). From this analysis, we propose a method for choosing the optimum grid
parameters (wire radius and spacing). We also provide a study of the effects of
two types of errors (in wire separation and radius size) that can be introduced
in the fabrication of a grid.Comment: 35 pages, 6 figure
Maximising response to postal questionnaires – A systematic review of randomised trials in health research
Background
Postal self-completion questionnaires offer one of the least expensive modes of collecting patient based outcomes in health care research. The purpose of this review is to assess the efficacy of methods of increasing response to postal questionnaires in health care studies on patient populations.
Methods
The following databases were searched: Medline, Embase, CENTRAL, CDSR, PsycINFO, NRR and ZETOC. Reference lists of relevant reviews and relevant journals were hand searched. Inclusion criteria were randomised trials of strategies to improve questionnaire response in health care research on patient populations. Response rate was defined as the percentage of questionnaires returned after all follow-up efforts. Study quality was assessed by two independent reviewers. The Mantel-Haenszel method was used to calculate the pooled odds ratios.
Results
Thirteen studies reporting fifteen trials were included. Implementation of reminder letters and telephone contact had the most significant effect on response rates (odds ratio 3.7, 95% confidence interval 2.30 to 5.97 p = <0.00001). Shorter questionnaires also improved response rates to a lesser degree (odds ratio 1.4, 95% confidence interval 1.19 to 1.54). No evidence was found that incentives, re-ordering of questions or including an information brochure with the questionnaire confer any additional advantage.
Conclusion
Implementing repeat mailing strategies and/or telephone reminders may improve response to postal questionnaires in health care research. Making the questionnaire shorter may also improve response rates. There is a lack of evidence to suggest that incentives are useful. In the context of health care research all strategies to improve response to postal questionnaires require further evaluation
Establishing Key Performance Indicators for Inflammatory Bowel Disease in the United Kingdom
Background and aimsHealthcare quality improvement (QI) is the systematic process to continuously improve the quality of care and outcomes for patients. The landmark Inflammatory Bowel Disease (IBD) UK National Audits provided a means to measure the variation in care, highlighting the need to define the standards of excellence in IBD care. Through a consensus approach, we aimed to establish key performance indicators (KPIs), providing reliable benchmarks for IBD care delivery in UK.MethodsKPIs that measure critical aspects of a patient journey within an IBD service were identified though stakeholder meetings. A two-stage Delphi consensus was then conducted. The first involved a multidisciplinary team of IBD clinicians and patients to refine definitions and methodology. The second stage assessed feasibility and utility of the proposed QI process by surveying gastroenterology services across UK.ResultsFirst, the four proposed KPIs were refined and included time from primary care referral to diagnosis in secondary care, time to treatment recommendation following a diagnosis, appropriate use of steroids and advanced therapies prescreening and assessment. Second, the Delphi consensus reported >85% agreement on the feasibility of local adoption of the QI process and >75% agreement on the utility of benchmarking of the KPIs.ConclusionsThrough a structured approach, we propose quantifiable KPIs for benchmarking to improve and reduce the individual variation in IBD care across the UK
Association of β-amyloid level, clinical progression and longitudinal cognitive change in normal older individuals
Objective To determine the effect of β-amyloid (Aβ) level on progression risk to mild cognitive impairment (MCI) or dementia and longitudinal cognitive change in cognitively normal (CN) older individuals. Methods All CN from the Australian Imaging Biomarkers and Lifestyle study with Aβ PET and ≥ 3 years follow-up were included (n = 534; age 72 ± 6 years; 27% Aβ positive; follow-up 5.3 ± 1.7 years). Aβ level was divided using the standardized 0–100 Centiloid scale: \u3c 15 CL negative, 15–25 CL uncertain, 26–50 CL moderate, 51–100 CL high, \u3e 100 CL very high, noting \u3e 25 CL approximates a positive scan. Cox proportional hazards analysis and linear mixed effect models were used to assess risk of progression and cognitive decline. Results Aβ levels in 63% were negative, 10% uncertain, 10% moderate, 14% high, and 3% very high. Fifty-seven (11%) progressed to MCI or dementia. Compared to negative Aβ, the hazard ratio for progression for moderate Aβ was 3.2 (95% confidence interval [CI] 1.3–7.6; p \u3c 0.05), for high was 7.0 (95% CI 3.7–13.3; p \u3c 0.001), and for very high was 11.4 (95% CI 5.1–25.8; p \u3c 0.001). Decline in cognitive composite score was minimal in the moderate group (−0.02 SD/year, p = 0.05), while the high and very high declined substantially (high −0.08 SD/year, p \u3c 0.001; very high −0.35 SD/year, p \u3c 0.001). Conclusion The risk of MCI or dementia over 5 years in older CN is related to Aβ level on PET, 5% if negative vs 25% if positive but ranging from 12% if 26–50 CL to 28% if 51–100 CL and 50% if \u3e 100 CL. This information may be useful for dementia risk counseling and aid design of preclinical AD trials
The Fifth Data Release of the Sloan Digital Sky Survey
This paper describes the Fifth Data Release (DR5) of the Sloan Digital Sky
Survey (SDSS). DR5 includes all survey quality data taken through June 2005 and
represents the completion of the SDSS-I project (whose successor, SDSS-II will
continue through mid-2008). It includes five-band photometric data for 217
million objects selected over 8000 square degrees, and 1,048,960 spectra of
galaxies, quasars, and stars selected from 5713 square degrees of that imaging
data. These numbers represent a roughly 20% increment over those of the Fourth
Data Release; all the data from previous data releases are included in the
present release. In addition to "standard" SDSS observations, DR5 includes
repeat scans of the southern equatorial stripe, imaging scans across M31 and
the core of the Perseus cluster of galaxies, and the first spectroscopic data
from SEGUE, a survey to explore the kinematics and chemical evolution of the
Galaxy. The catalog database incorporates several new features, including
photometric redshifts of galaxies, tables of matched objects in overlap regions
of the imaging survey, and tools that allow precise computations of survey
geometry for statistical investigations.Comment: ApJ Supp, in press, October 2007. This paper describes DR5. The SDSS
Sixth Data Release (DR6) is now public, available from http://www.sdss.or
The \u3cem\u3eChlamydomonas\u3c/em\u3e Genome Reveals the Evolution of Key Animal and Plant Functions
Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the ∼120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella
British Society of Gastroenterology guidance for management of inflammatory bowel disease during the COVID-19 pandemic.
The COVID-19 pandemic is putting unprecedented pressures on healthcare systems globally. Early insights have been made possible by rapid sharing of data from China and Italy. In the UK, we have rapidly mobilised inflammatory bowel disease (IBD) centres in order that preparations can be made to protect our patients and the clinical services they rely on. This is a novel coronavirus; much is unknown as to how it will affect people with IBD. We also lack information about the impact of different immunosuppressive medications. To address this uncertainty, the British Society of Gastroenterology (BSG) COVID-19 IBD Working Group has used the best available data and expert opinion to generate a risk grid that groups patients into highest, moderate and lowest risk categories. This grid allows patients to be instructed to follow the UK government's advice for shielding, stringent and standard advice regarding social distancing, respectively. Further considerations are given to service provision, medical and surgical therapy, endoscopy, imaging and clinical trials
Antibody decay, T cell immunity and breakthrough infections following two SARS-CoV-2 vaccine doses in inflammatory bowel disease patients treated with infliximab and vedolizumab
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