Dataset Information

The minimum crystal size needed for a complete diffraction data set.

ABSTRACT: In this work, classic intensity formulae were united with an empirical spot-fading model in order to calculate the diameter of a spherical crystal that will scatter the required number of photons per spot at a desired resolution over the radiation-damage-limited lifetime. The influences of molecular weight, solvent content, Wilson B factor, X-ray wavelength and attenuation on scattering power and dose were all included. Taking the net photon count in a spot as the only source of noise, a complete data set with a signal-to-noise ratio of 2 at 2 A resolution was predicted to be attainable from a perfect lysozyme crystal sphere 1.2 microm in diameter and two different models of photoelectron escape reduced this to 0.5 or 0.34 microm. These represent 15-fold to 700-fold less scattering power than the smallest experimentally determined crystal size to date, but the gap was shown to be consistent with the background scattering level of the relevant experiment. These results suggest that reduction of background photons and diffraction spot size on the detector are the principal paths to improving crystallographic data quality beyond current limits.

SUBMITTER: Holton JM

PROVIDER: S-EPMC2852304 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The minimum crystal size needed for a complete diffraction data set.

Holton James M JM Frankel Kenneth A KA

Acta crystallographica. Section D, Biological crystallography 20100324 Pt 4

In this work, classic intensity formulae were united with an empirical spot-fading model in order to calculate the diameter of a spherical crystal that will scatter the required number of photons per spot at a desired resolution over the radiation-damage-limited lifetime. The influences of molecular weight, solvent content, Wilson B factor, X-ray wavelength and attenuation on scattering power and dose were all included. Taking the net photon count in a spot as the only source of noise, a complet ...[more]

PMID: 20382993

Similar Datasets

Project description:BACKGROUND: over the last 25 years several national registries of CF have been set up. Such systems can be very useful in providing an integrated resource for improving patient care and conducting research on the disease. Minimum Data Set is a common set of data items that should be used to collect and report data in the registry. The principal aim of this research was to determine minimum data set for the CF registry in north-west of Iran. METHODS: data items collected by several selected registries of cystic fibrosis were studied and an initial set of data was selected by the researchers. A group of experts including epidemiologists, pediatricians, and CF specialists were asked to review the proposed data elements and score them based on their importance by using a nine-point Likert scale. The items scored as important or highly important by more than 50 % of the experts, were included in final list of minimum data set. Availability of data was evaluated through reviewing medical records of 144 patients hospitalized in Children Hospital located in Tabriz. RESULTS: overall six classes of data (46 items) were identified in the selected registry systems for cystic fibrosis: patient demographics, administrative data, survival status, diagnostic procedures, genetic and clinical manifestations, and therapeutics. Thirty two data elements from all six categories of data were approved by the experts as the minimum data set for cystic fibrosis registry system. Availability of data in administrative category and survival class was 100 percent. Collecting data on medications was feasible in 100% of the cases as well. In class of demographic data, accessibility of patient name, age, gender, place of birth, and date of birth was 100 percent. In group of diagnostic procedures, partial availability of data was found for sweat test and genetic test. No data was found on the antenatal screening, exercise tolerance test, and glucose tolerance test. CONCLUSION: this work can be considered as a first step toward establishing CF registry system in Iran. Minimum data set can be also useful in designing electronic registry or electronic patient records for those suffering from CF toward integration of their fragmented records across continuum of the health care system in order to improve quality of shared patient care.

Project description:BackgroundThe Resident Assessment Instrument-Minimum Data Set (RAI-MDS) 2.0 is designed to collect the minimum amount of data to guide care planning and monitoring for residents in long-term care settings. These data have been used to compute indicators of care quality. Use of the quality indicators to inform quality improvement initiatives is contingent upon the validity and reliability of the indicators. The purpose of this review was to systematically examine published and grey research reports in order to assess the state of the science regarding the validity and reliability of the RAI-MDS 2.0 Quality Indicators (QIs).MethodsWe systematically reviewed the evidence for the validity and reliability of the RAI-MDS 2.0 QIs. A comprehensive literature search identified relevant original research published, in English, prior to December 2008. Fourteen articles and one report examining the validity and/or reliability of the RAI-MDS 2.0 QIs were included.ResultsThe studies fell into two broad categories, those that examined individual quality indicators and those that examined multiple indicators. All studies were conducted in the United States and included from one to a total of 209 facilities. The number of residents included in the studies ranged from 109 to 5758. One study conducted under research conditions examined 38 chronic care QIs, of which strong evidence for the validity of 12 of the QIs was found. In response to these findings, the 12 QIs were recommended for public reporting purposes. However, a number of observational studies (n = 13), conducted in "real world" conditions, have tested the validity and/or reliability of individual QIs, with mixed results. Ten QIs have been studied in this manner, including falls, depression, depression without treatment, urinary incontinence, urinary tract infections, weight loss, bedfast, restraint, pressure ulcer, and pain. These studies have revealed the potential for systematic bias in reporting, with under-reporting of some indicators and over-reporting of others.ConclusionEvidence for the reliability and validity of the RAI-MDS QIs remains inconclusive. The QIs provide a useful tool for quality monitoring and to inform quality improvement programs and initiatives. However, caution should be exercised when interpreting the QI results and other sources of evidence of the quality of care processes should be considered in conjunction with QI results.

Project description:BackgroundTo improve care, planners require accurate information about nursing home (NH) residents and their healthcare use. We evaluated how accurately measures of resident user status and healthcare use were captured in the Minimum Data Set (MDS) versus administrative data.MethodsThis retrospective observational cohort study was conducted on all NH residents (N = 8832) from Winnipeg, Manitoba, Canada, between April 1, 2011 and March 31, 2013. Six study measures exist. NH user status (newly admitted NH residents, those who transferred from one NH to another, and those who died) was measured using both MDS and administrative data. Rates of in-patient hospitalizations, emergency department (ED) visits without subsequent hospitalization, and physician examinations were also measured in each data source. We calculated the sensitivity, specificity, positive and negative predictive values (PPV, NPV), and overall agreement (kappa, κ) of each measure as captured by MDS using administrative data as the reference source. Also for each measure, logistic regression tested if the level of disagreement between data systems was associated with resident age and sex plus NH owner-operator status.ResultsMDS accurately identified newly admitted residents (κ = 0.97), those who transferred between NHs (κ = 0.90), and those who died (κ = 0.95). Measures of healthcare use were captured less accurately by MDS, with high levels of both under-reporting and false positives (e.g., for in-patient hospitalizations sensitivity = 0.58, PPV = 0.45), and moderate overall agreement levels (e.g., κ = 0.39 for ED visits). Disagreement was sometimes greater for younger males, and for residents living in for-profit NHs.ConclusionsMDS can be used as a stand-alone tool to accurately capture basic measures of NH use (admission, transfer, and death), and by proxy NH length of stay. As compared to administrative data, MDS does not accurately capture NH resident healthcare use. Research investigating these and other healthcare transitions by NH residents requires a combination of the MDS and administrative data systems.

Dataset Information

The minimum crystal size needed for a complete diffraction data set.

Publications

The minimum crystal size needed for a complete diffraction data set.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets