Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

An investigation into the professional ideology of the Neighbourhood Level Community Development Projects community workers

published_or_final_versionSocial WorkMasterMaster of Social Wor

Item Identification and Fictitious Ratings on relevance of 27-Item Scale by Experts.

<p>Item Identification and Fictitious Ratings on relevance of 27-Item Scale by Experts.</p

Mean scores and distribution of responses to individual items, and Internal consistency for each scale.

<p>Note:</p><p>NA = Not applicable due to small number of items.</p

Factor loadings for 27-item Barrier to Insulin Questionnaire.

<p>Note:</p><p>Factors were extracted by exploratory factor (principal component) analysis with varimax rotation.</p><p>The Kaiser–Meyer–Olkin (KMO) measure was 0.725.</p

Development and Validation of the Chinese Attitudes to Starting Insulin Questionnaire (Ch-ASIQ) for Primary Care Patients with Type 2 Diabetes

<div><p>Objectives</p><p>To develop and evaluate the psychometric properties of a Chinese questionnaire which assesses the barriers and enablers to commencing insulin in primary care patients with poorly controlled Type 2 diabetes.</p><p>Research Design and Method</p><p>Questionnaire items were identified using literature review. Content validation was performed and items were further refined using an expert panel. Following translation, back translation and cognitive debriefing, the translated Chinese questionnaire was piloted on target patients. Exploratory factor analysis and item-scale correlations were performed to test the construct validity of the subscales and items. Internal reliability was tested by Cronbach’s alpha.</p><p>Results</p><p>Twenty-seven identified items underwent content validation, translation and cognitive debriefing. The translated questionnaire was piloted on 303 insulin naïve (never taken insulin) Type 2 diabetes patients recruited from 10 government-funded primary care clinics across Hong Kong. Sufficient variability in the dataset for factor analysis was confirmed by Bartlett’s Test of Sphericity (P<0.001). Using exploratory factor analysis with varimax rotation, 10 factors were generated onto which 26 items loaded with loading scores > 0.4 and Eigenvalues >1. Total variance for the 10 factors was 66.22%. Kaiser-Meyer-Olkin measure was 0.725. Cronbach’s alpha coefficients for the first four factors were ≥0.6 identifying four sub-scales to which 13 items correlated. Remaining sub-scales and items with poor internal reliability were deleted. The final 13-item instrument had a four scale structure addressing: ‘Self-image and stigmatization’; ‘Factors promoting self-efficacy; ‘Fear of pain or needles’; and ‘Time and family support’.</p><p>Conclusion</p><p>The Chinese Attitudes to Starting Insulin Questionnaire (Ch-ASIQ) appears to be a reliable and valid measure for assessing barriers to starting insulin. This short instrument is easy to administer and may be used by healthcare providers and researchers as an assessment tool for Chinese diabetic primary care patients, including the elderly, who are unwilling to start insulin.</p></div