Deuterium uptake in magnetic-fusion devices with lithium-conditioned carbon walls.

Lithium wall conditioning has lowered hydrogenic recycling and dramatically improved plasma performance in many magnetic-fusion devices. In this Letter, we report quantum-classical atomistic simulations and laboratory experiments that elucidate the roles of lithium and oxygen in the uptake of hydrogen in amorphous carbon. Surprisingly, we show that lithium creates a high oxygen concentration on a carbon surface when bombarded by deuterium. Furthermore, surface oxygen, rather than lithium, plays the key role in trapping hydrogen.

Accurate activity determination of a californium neutron source.

Accurately counting analog events requires constructing an electronics chain that produces one count for each input pulse. In this work we review the use of Nuclear Instrumentation Module electronic units for counting neutron capture events in a 3He tube. We identify two unique types of false trigger events in a leading-edge discriminator and show how a dual timer module can be used to produce a veto window to exclude these events. We use the constructed electronics chain to build an apparatus to measure neutron pulses from a 252Cf neutron source. We compare the measurements with a Monte Carlo N-Particle (MCNP) model to determine the activity of the neutron source. Furthermore, by making additional measurements with borated polyethylene attenuators between the source and detector, we are able to determine the boron concentration of the polyethylene. This technique provides accurate determination of the source activity to a precision of 2.8% at the k = 1 level. The method used is simple, inexpensive, and requires no additional calibrated instruments.

Anthelmintic treatment of rural Bangladeshi children: effect on host physiology, growth, and biochemical status.

BACKGROUND: The effect of helminth infestation on the nutrition, growth, and physiology of the host is still poorly understood. Anthelmintic treatment of children in developing countries has had varying success in terms of growth improvements. OBJECTIVE: The objective of this study was to assess the effect of regular deworming on child growth, physiology, and biochemical status. DESIGN: The study was a 12-mo longitudinal intervention in 123 Bangladeshi children aged 2-5 y. Treatment (mebendazole) or placebo tablets were administered every 2 mo for 8 mo and again at 12 mo. Weight, height, midupper arm circumference, intestinal permeability, plasma albumin, alpha(1)-antichymotrypsin, and total protein concentration were assessed every 2 mo. RESULTS: Treatment with mebendazole reduced the prevalence of Ascaris lumbricoides from 78% to 8%, of Trichuris trichiura from 65% to 9%, and of hookworm from 4% to 0%. There was no significant difference in the growth of treated children compared with those given placebo tablets. No changes in intestinal permeability or plasma albumin were observed after deworming. Significant decreases in total protein (P<0.001) and alpha(1)-antichymotrypsin (P<0.001) were observed in the treatment group, indicating possible reductions in inflammation and immunoglobulin concentration after deworming. A significant increase in the prevalence of Giardia intestinalis (from 4% to 49%) in the treatment group was associated with a short-term reduction in weight (P = 0.02) and higher intestinal permeability (P <0.001) in infected subjects. No long-term effects of G. intestinalis on growth were observed. CONCLUSION: Low-intensity helminth infections, predominantly of A. lumbricoides and T. trichiura, do not contribute significantly to the poor growth and biochemical status of rural Bangladeshi children.

General practitioner notes as a source of information for case-control studies in young women. UK National Case-Control Study Group.

STUDY OBJECTIVE: The UK National Case-Control Study was carried out to investigate the relationship between oral contraceptive use and breast cancer risk. This study investigates whether general practitioner notes could be used as the sole data source for epidemiological studies of young women and what the effect would be on non-response and recall bias. DESIGN: Case-control study with data on gynaecological, obstetric, and contraceptive history collected at interview and from general practitioners' notes. Information from these two sources was compared. SETTING: This was a population-based study. PARTICIPANTS: Altogether 755 women with breast cancer aged under 36 years at diagnosis, each with an age-matched control, participated in the study. Response rates at interview were 72% and 89% for cases and controls but GP data were available for 90% of the 1049 case and first-selected control pairs. MAIN RESULTS: There was generally good agreement between the two data sources with respect to obstetric history and gynaecological procedures (hysterectomy, oophorectomy, and tubal ligation). The use of intra-uterine devices, or diaphragm, and partner's vasectomy were not reliably recorded in the GP's notes. The overall results of the UK study would have been qualitatively the same with respect to the relationship between oral contraceptive use and breast cancer risk if GP notes only had been used, in spite of the fact that only about half of all oral contraceptive usage was recorded in the notes. Response rates would have been higher, recall bias eliminated, and the cost of the study halved. CONCLUSIONS: When planning case-control studies in young women, the possibility of using GP notes as the primary data source should be considered. Lack of data on potential confounding factors is a possible drawback to such use. The practice of destroying GP's notes shortly after the death of patients seriously restricts the possibility of using these notes when studying rapidly fatal conditions.

Materials analysis and particle probe: a compact diagnostic system for in situ analysis of plasma-facing components (invited).

The objective of the materials analysis particle probe (MAPP) in NSTX is to enable prompt and direct analysis of plasma-facing components exposed to plasma discharges. MAPP allows multiple samples to be introduced to the level of the plasma-facing surface without breaking vacuum and analyzed using X-ray photoelectron spectroscopy (XPS), ion-scattering and direct recoil spectroscopy, and thermal desorption spectroscopy (TDS) immediately following the plasma discharge. MAPP is designed to operate as a diagnostic within the ∼12 min NSTX minimum between-shot time window to reveal fundamental plasma-surface interactions. Initial calibration demonstrates MAPP's XPS and TDS capabilities.

Primary health care, policy makers and health education: some challenging goals.

A challenge to politicains and health administrators everywhere, and therefore to health education, is how to achieve a more equitable distribution of health care to the people. A new approach that may well be the answer is the use of primary health care, which is concerned with measures that will provide simple and effective health care to all people. The priniciples on which primary health care is based have much in common with those of health education, as spelled out over the past 20 years by WHO expert committees, namely: involving people in a working partnership respecting their values and beliefs, placing reliance on indigenous practitioners, etc. In both cases, "the focus is on people and action" and the primary health care context offers a challenging opportunity for health education to make a major contribution towards a fairer distribution of health services. Another area where health education has a particular challenge to meet concerns the education of politicians at all levels: health educators must do all they can to influence health and health-related policy away from those determined solely by political expediency and towards policies that benefit the people. They must also help bridge the gap between "deciding politicians" and the "consuming citizen" to help ensure that the decisions of the former meet the needs of the latter.

Life stress and symptom pattern in out-patient depression.

The relationship was examined between symptoms rated in a sample of out-patient depressives, and measures of life stress derived from a separate interview. There was an association between symptoms reflecting the endogenous-neurotic distinction and life stress. However, the association was relatively weak, and was mainly with total social problems at the time of presentation, rather than with life events at onset. These findings are consistent with other studies which indicate that the absence of prior life events and the presence of the endogenous symptom pattern are only weakly related.

Oral contraceptive use and histopathology of cancerous breasts in young women. Members of the U.K. National Case-Control Study Group.

A retrospective histopathological study of 300 women under 36 years of age was carried out to determine whether breast cancers occurring in oral contraceptive users showed any differences in pathological features compared with non-users. The patients belong to an age group in which an increased risk of cancer development has been reported following oral contraceptive usage. The incidence of non-neoplastic conditions in the residual breast was also studied in the two groups. There was little difference between breast cancers arising in pill users and non-users but in the residual non-neoplastic breast a decreased incidence of cysts and blunt duct adenosis was found in current users of the contraceptive pill. In contrast, lactational foci were found only in the breasts of pill users. The incidence of intraductal hyperplasia was not significantly different in the two groups.

Asymptomatic, palpable, anterior chest wall lesions in children: is cross-sectional imaging necessary?

PURPOSE: To review results from cross-sectional imaging studies performed to evaluate asymptomatic anterior chest wall lesions in children. MATERIALS AND METHODS: All magnetic resonance (MR) images or computed tomographic (CT) scans of the chest obtained from 1989 to 1996 for evaluation of asymptomatic, palpable, focal, anterior chest wall lesions in otherwise healthy children were reviewed. Fifty-one children were considered for the study. Findings from 27 examinations in 27 children (13 underwent MR imaging, and 14 underwent CT) were included in the study. All children had normal radiographs of the region. Twenty-four patients did not meet the inclusion criteria and were excluded. RESULTS: The cause of the lesion palpated at physical examination was identified in 26 of 27 patients: prominent anterior convex ribs in 10 patients; "tilted" sternum in six; prominent asymmetric costal cartilage in four; bifid rib in one; and well-defined, small (< 1-cm) subcutaneous nodule adjacent to costal cartilage in five. One examination demonstrated no abnormality. Of the 27 patients, none required treatment. CONCLUSION: All palpable, asymptomatic, anterior chest wall lesions were benign and usually related to normal variations in the bone or cartilage of the chest wall. The low yield of cross-sectional imaging performed for evaluation of these asymptomatic "bumps" should be considered when decisions are made with regard to imaging.

Nosology of atypical depression.

A review of the literature on atypical depression indicated three relatively separate usages for the term: anxiety or phobic symptoms additional to depression, reversed functional shift, and non-endogenous depression. A sample of 160 out-patient depressives was rated on a variety of diagnostic systems measuring these concepts. Inter-relationships between groups selected by the three definitions were found to be low. In addition, although there was moderate consistency within different definitions of endogenous depression and of additional anxiety, reversed functional shift symptoms did not correlate well with each other. These findings suggest that atypical depression may be of limited value as a specific diagnosis within non-psychotic depression.