无源效率刻度在马林杯状气体源活度测量中的应用

目的利用LabSOCS无源效率刻度软件模拟优化马林杯状源盒,探究HPGe探测器测量惰性气体的探测效率,为核电站惰性气体流出物的测量优化提供参考。方法利用LabSOCS软件建立了马林杯模型,探究各惰性气体γ射线的探测效率随气体成分、气体密度、马林杯尺寸参数、马林杯体积、测量源盒形状的变化关系。结果气体成分对马林杯中惰性气体的探测效率几乎没有影响,低能γ射线的探测效率受气体密度影响较大,选择合适的马林杯高度和半径能够使HPGe探测器获得更好的测量结果。对于BE5030 HPGe探测器,不同体积的马林杯探测效率最高值均位于半径/高度=0.7位置处,并给出不同体积的马林杯高度和半径的最优值。结论选择合适的马林杯尺寸能够提高核电站流出物中惰性气体的探测效率。     

Bone-lead analysis: Development of analytical methodology for milligram samples

A graphite platform-in-furnace atomic absorption spectrometric (GFAAS) method for determining g/g levels of Pb in 10–20 mg cortical and trabecular primate bone samples is described. The GFAAS method is based on an ambient temperature nitric acid digestion of the sample, matrix modification with palladium nitrate, stabilized temperature platform furnace atomization, and a systematic evaluation of the temperature program of the atomizer. The method of standard additions is mandatory. The detection limit (3 standard deviations of the blank) is 0.19 g Pb/g dry weight for a 10-mg sample taken up in a 1-mL volume. Data are presented on the degree of accuracy and precision. The accuracy of the proposed GFAAS method has been assessed using the IAEA bone reference material, H-5, and by comparing the values obtained in a bone sample with an isotope dilution mass spectrometric (IDMS) procedure. The GFAAS method can be applied to the determination of Pb in 10–20 mg bone samples and for concentrations which are 10 × detection limit. The method is simple, fast, and contamination-free since the entire operation from weighing to GFAAS measurement is carried out in the same centrifuge tube. The method has been applied to the determination of total-Pb in some adult and fetal primate cortical and trabecular bone specimens.     

Leasing vs. owning a medical office: an analytical model

Physicians often face a major financial dilemma: To lease or own their medical office. This article takes a set of typical assumptions for a real estate market and analyzes the capital costs, cash flow, and investment implications of the option of leasing a medical office versus owning a similar property. The paper analyzes the financial aspects of each option and the impact on net physician income and potential return-on-investment. A model for analysis is presented that can be used by practitioners who advise physicians in such decision-making.     

Biomarkers of oxidative stress: an analytical approach

Oxidative stress is implicated in many pathological processes and results from a disruption of the prooxidant/antioxidant balance. This review will focus on noninvasive biomarkers of radical-induced damage in biological fluids and particularly in blood. Special attention will be addressed to new analytical methods for the measurement of radical-mediated alterations in the integrity of lipids, proteins and DNA.     

Study of an analytical method for hexavalent chromium

The diphenylcarbazide colorimetric method was evaluated by analyzing spiked PVC filters prepared by an AIHA-accredited consultant laboratory for chromium (VI). All seven participating laboratories received the samples and performed the analyses at the same time. Three laboratories simultaneously tested three alternative analytical procedures. Reduced amounts of chromium (VI) were found by both the consultant and participating laboratories when using the test procedure and one of the alternative methods. Two of the alternative analytical methods, both of which involve an alkaline extraction procedure, provided higher recoveries and more precise values for the test filters. It appears that the alkaline extraction procedure may be more appropriate for occupational health samples taken in steel industry environments which may include several interferents. Suggestions are made for further studies to determine the most appropriate analytical method.     

Concept maps in medical education: an analytical literature review

Medical Education 2010: 44 : 440–448 Objectives As the medical profession continues to change, so do the educational methods by which medical students are taught. Various authors have acknowledged the need for alternative teaching and learning strategies that will enable medical students to retain vast amounts of information, integrate critical thinking skills and solve a range of complex clinical problems. Previous research has indicated that concept maps may be one such teaching and learning strategy. This article aims to: (i) review the current research on concept maps as a potential pedagogical approach to medical student learning, and (ii) discuss implications for medical student teaching and learning, as well as directions for future research. Methods The literature included in this review was obtained by searching library databases including ACADEMIC SEARCH, ERIC, EBSCOHost, PsychINFO, PsychARTICLES, PubMed/MEDLINE, CINAHL and EMBASE. This literature review is a summary of both conceptual and empirically published literature on the uses of concept mapping in medical education. Results The 35 studies reviewed here indicate that concept maps function in four main ways: (i) by promoting meaningful learning; (ii) by providing an additional resource for learning; (iii) by enabling instructors to provide feedback to students, and (iv) by conducting assessment of learning and performance. Conclusions This review provides ideas for medical school faculty staff on the use of concept maps in teaching and learning. Strategies such as fostering critical thinking and clinical reasoning, incorporating concept mapping within problem‐based learning, and using concept mapping in group and collaborative learning are identified. New developments in medical education include the use of serial concept maps, concept maps as a methodology to assist learners with lower cognitive competence, and the combination of group concept maps with structured feedback.     

Photon specific absorbed fractions calculated in the trunk of an adult male voxel-based phantom.

A new approach for calculating internal dose estimates was developed through the use of a more realistic computational model of the human body. The study demonstrates the capability of building a patient-specific phantom with voxel-based data for the simulation of radiation transport and energy deposition using Monte Carlo methods such as the MCNP-4B code. MCNP-4B was used to calculate absorbed fractions for photons in a voxel-based phantom, and values were compared to reference values from traditional phantoms used for many years. Results obtained in general agreed well with previous values, but considerable differences were found in some cases due to two major causes; differences in the organ masses between the phantoms and the occurrence of organ overlap in the voxel-based phantom (which is not well modeled in the mathematical phantoms). These new techniques offer promise of developing a new generation of more realistic phantoms for internal, as well as external, dose assessment. The principal area of implementation in internal dose assessment should be the development of patient-specific dose estimates in nuclear medicine therapy, such as radioimmunotherapy (RIT). However, as new voxel-based phantoms for different individuals can be developed, they may also be used with the techniques developed here to derive new absorbed fractions and replace the traditional values usedfor other applications in internal and external dose assessment, which have been based on mathematical constructs that are not always very representative of real human organs.     

Variation in the protection periods of repellents on individual human subjects: an analytical review.

Mosquito repellent test data from the literature were analyzed to estimate mean protection periods and among-subjects standard deviations. Standard deviations were a linear function of the means. Numbers of subjects needed to determine mean protection periods of 1-8 h with confidence limits of +/- 0.5, 1.0, 1.5, and 2.0 h at the 99 and 95% levels of confidence were computed from regression values of the standard deviation, and a table of sample sizes was constructed for use in planning repellent tests.     

Photon shielding for 241Am surface and point sources.

To determine radiation protection requirements for work with actinide elements, a method for rapidly estimating effective dose-equivalent rates from low-energy photons has been developed. This paper describes results obtained from a personal computer program that incorporates the point kernel technique to predict radiation fields from shielded and unshielded sources containing 241Am. Information generated has been used to determine procedures and to design facilities for handling actinides at Argonne National Laboratory's site at the Idaho National Engineering Laboratory. Area or point sources can be treated; effects of Compton scattering in air and in solid shields are considered. Users can select an appropriate response function; their choice has a strong influence on predicted dose rates from unshielded sources.     

Investigation of photon attenuation coefficients for marble.

The total linear attenuation coefficients micro (cm(-1)) have been obtained using the XCOM program at photon energies of 1 keV to 1 GeV for six different natural marbles produced in different places in Turkey. The individual contribution of photon interaction processes to the total linear attenuation coefficients for marble has been investigated. The calculated results were also compared with the measurements. The results obtained for marble were also compared with concrete.     

Infant feeding policies in maternity wards and their effect on breast-feeding success: an analytical overview.

OBJECTIVES. The purpose of this review is to examine the plausibility of a causal relationship between maternity ward practices and lactation success. METHODS. Studies were located with MEDLINE, from our personal files, and by contacting researchers working in this field. Of the 65 studies originally reviewed, 18 met our inclusion criteria (i.e., hospital-based intervention, experimental design with randomization procedures, or quasi-experimental design with adequate documentation). RESULTS. Meta-analysis indicated that commercial discharge packs had an adverse effect on lactation performance. The impact of early mother-infant contact on lactation success was unclear. Rooming-in and breast-feeding guidance in a rooming-in context had a beneficial impact on breast-feeding among primiparae. Breast-feeding on demand was positively associated with lactation success. In-hospital formula supplementation of 48 mL per day was not associated with poor breast-feeding performance. CONCLUSIONS. Hospital-based breast-feeding interventions can have a beneficial effect on lactation success, particularly among primiparous women.     

Integrating health services into an MCH-FP program in Matlab, Bangladesh: an analytical update

This is a follow-up to a 1984 study that analyzed the relationship between areal variation in the contraceptive prevalence time series and in the intensity of maternal and child health (MCH) services of the Matlab Family Planning Health Services Project. Results based on 69 months of observation suggested that the addition of MCH components to a program with basic MCH and comprehensive family planning services had no incremental impact on family planning efficacy. However, basic MCH services, involving clinical back-up to family planning and child care since the beginning of the program in Matlab, may have contributed to clients' faith in the clinic staff and the overall efficacy of the Matlab program. In the 18 months that followed the cut-off date for this analysis, contraceptive prevalence increased markedly in the study areas. The present analysis repeats the earlier one for the extended time series to determine if the intensification of health services in Matlab contributed to this secondary increase in prevalence, and to ascertain whether the MCH service regimes have long-run differential impacts. Results for the 87-month time series are similar to those of the previous analysis, suggesting that the introduction of additional MCH inputs in the Matlab service area over the 1982-83 period had no incremental impact on the contraceptive prevalence rate time trend.     

Drivers for emigration among healthcare professionals: Testing an analytical model in a primary healthcare setting

This paper aims to contribute to the discussion on health workforce migration, notably by testing an analytical model of the individual drivers for a professional to decide to emigrate.A large database was obtained from all primary health care units on mainland Portugal. A professional satisfaction survey was conducted and information on social-economic, labour and job satisfaction characteristics, including burnout, was obtained.Results showed that healthcare professionals who reported intention to emigrate are mostly male, young, not married, and more educated; they consider their income insufficient for their needs, and show higher levels of burnout at work and professional dissatisfaction. This profile is slightly different for GPs and nurses.The results obtained contribute to the discussion on what motivates primary health care professionals, including GPs and nurses, to emigrate. They also provide insight into the design of policy measures that may mitigate the intention of these healthcare professionals in general to emigrate.     

Techniques for the computation in demographic projections of health manpower.

Some basic principles and algorithms are presented which can be used for projective calculations of medical staff on the basis of demographic data. The effects of modifications of the input data such as by health policy measures concerning training capacity, can be demonstrated by repeated calculations with assumptions. Such models give a variety of results and may highlight the probable future balance between health manpower supply and requirements.     

车间空气中正丁醇的气相色谱测定方法研究

使一定量现场空气通过活性炭采样管以采集正丁醇。用含1％异丙醇的二硫化碳溶液解吸,取解吸的样品溶液注入气相色谱仪。测量峰高,并与注入标准所得峰高相比较,计算空气中正丁醇的含量。在给定的实验条件下,方法的变异系数低于1.6％,解吸效率平均为97.9％,100mg活性炭对正丁醇的穿透容量为15.03mg,检测限为5.3×10~(-4)μg。经过现场测试,本方法可用于工业卫生监测。色谱条件:2m不锈钢柱,充填10％FFAP/chromosorb W-AW(60～80目);载气(N_2)50ml/min;柱温80℃:检测室温度180℃。     

Complexity and indeterminism of evidence-based public health: an analytical framework

Improving the evidence in public health is an important goal for the health promotion community. With better evidence, health professionals can make better decisions to achieve effectiveness in their interventions. The relative failure of such evidence in public health is well-known, and it is due to several factors. Briefly, from an epistemological point of view, it is not easy to develop evidence-based public health because public health interventions are highly complex and indeterminate. This paper proposes an analytical explanation of the complexity and indeterminacy of public health interventions in terms of 12 points. Public health interventions are considered as a causal chain constituted by three elements (intervention, risk factor, and disease) and two levels of evaluation (risk factor and disease). Public health interventions thus differ from clinical interventions, which comprise two causal elements and one level of evaluation. From the two levels of evaluation, we suggest a classification of evidence into four typologies: evidence of both relations; evidence of the second (disease) but not of the first (risk factor) relation; evidence of the first but not of the second relation; and no evidence of either relation. In addition, a grading of indeterminacy of public health interventions is introduced. This theoretical point of view could be useful for public health professionals to better define and classify the public health interventions before acting.