Ultrastructure of bacteriophages specific for Bacillus thuringiensis var. galleriae

Fine structure of the phage specific for Bacillus thuringiensis var. galleriae was studied. The head of the phage is of the elongated hexagonal shape, 600 X 360 A. The tail is 400 X 40 A large and has a thickening in the basal part (70 X 120 A). A so-called "collar" structure is found at the site where the head joins the tail. This a disc-shaped plate with a diameter of 120 A and a hole in the centre; 12 fillaments are attached to it radially and terminated with tines. It is possible that the structure is necessary for adsorption of the phage on the cell.     

The influence of some compounds commonly used in biochemical studies of mitochondria on the activity of monoamine oxidases

It was previously described that low concentrations of sodium azide monoamine oxidase (MAO) B assayed by spectrophotometric measurement of benzaldehyde or by hydrogen peroxide accumulation. We failed to confirm this effect using radiometric determination of MAO activity. Tris or dinitrophenol inhibit MAO. The data suggest that some "regulatory effects" depend on the assay of MAO activity.     

超高密度钻井液技术进展

超高密度钻井液是当今石油钻井行业的前沿技术之一,涉及到多方面的研究内容.从室内研究、现场应用两方面分析了超高密度(≥2.50g/cm3)钻井液研究中存在的技术问题,对钻井液使用的加重材料、降滤失剂、流动性改善剂等关键材料的研究进展进行了分析和论述,指出了超高密度钻井液配方优选时应注意的几个问题,介绍了超高密度钻井液流变学特征的研究概况,探讨了超高密度钻井液密度的技术途径,分析了特高密度钻井液技术的可行性.提出的各种方案和建议对室内研究和现场操作均有较好的借鉴意义.     

Performance of "standardized examinees" in a standardized-patient examination of clinical skills

PURPOSE: As a first step in testing the utility of using trained "standardized examinees" (SEs) as a quality-assurance measure for the scoring process in a standardized-patient (SP) examination, to test whether medical residents could simulate students in an SP examination and perform consistently to specified levels under test conditions. METHOD: Fourth-year students from the Baltimore-Washington Consortium for SPs participated in a National Board of Medical Examiners Prototype Examination of clinical skills consisting of twelve 15-minute student-patient encounters in 1994-95. For this examination, internal medicine residents were trained to act as ordinary candidates and to achieve target scores by performing to a set level on specific checklist items used by SPs for recording interviewing, physical-examination, and communication skills. The "strong SEs" were trained to score 80% correct on six of the examination's 12 cases (study cases), and the "weak SEs" were trained to score 40% correct on the same six cases. The strong and weak SEs' checklist scores on the study cases were compared through independent, two-tailed t-tests. When there was less than 85% agreement on specific checklist items in each case between the SE training and the SP recording, videotapes of the cases were reviewed; in such cases an SE's performance was the final score agreed upon after review. RESULTS: Seven SEs took the SP examination and were not detected by the SPs. There was a total of 84 discrepancies between predicted and recorded checklist scores across 659 checklist items in 40 encounters scored by the SPs. After correcting the discrepancies based on videotape review, the estimated actual mean score was 77.3% for the strong SEs and 44.0% for the weak SEs, and was higher for the strong SEs in each study case. The overall fidelity of the SEs to their training was estimated to be 97%, and the overall SP accuracy was estimated to be 91%. The videotape review revealed 47 training-scoring discrepancies, most in the area of communication skills. CONCLUSION: This study suggests that SEs can be trained to specific performance levels and may be an effective internal control for a high-stakes SP examination. They may also provide a mechanism for refining scoring checklists and for exploring the validity of SP examinations.     

Preventing sleep problems in infants: a randomized controlled trial

In the pre-school years sleep problems are one of the most common subjects on which parents seek advice from health professionals. In the majority of cases a sleepless child causes significant stress within the family, and if parents do not obtain sufficient sleep this can have a detrimental effect on their physical and emotional well-being. In a small number of cases a child who wakes frequently and will not settle back to sleep may be at risk of physical abuse. In recent years it has been suggested that it may be possible to prevent sleep problems developing by providing parents with advice in the post-natal period. Parents have stated that they find this type of intervention helpful, however, there has been no attempt to establish whether a preventive approach is effective. The aim of this research was to evaluate the efficacy of health education in reducing the incidence of sleep problems. Adopting an experimental approach, participants were randomly allocated to a control group or an intervention group. Parental knowledge of sleep and settling behaviour was manipulated when the children in the intervention group were 3 months old. The sleeping behaviour of the infants in both groups was compared 6 months later, when the children were 9 months old. Data was collected from 86 families in the intervention group and 83 families in the control group. A comprehensive analysis of the sleeping behaviour demonstrated that a significantly smaller percentage of babies in the intervention group had settling and night-waking difficulties than in the control group.