Deep Impact collided with comet Tempel 1, excavating a crater controlled by gravity. The comet's outer layer is composed of 1- to 100-micrometer fine particles with negligible strength (<65 pascals). Local gravitational field and average nucleus density (600 kilograms per cubic meter) are estimated from ejecta fallback. Initial ejecta were hot (>1000 kelvins). A large increase in organic material occurred during and after the event, with smaller changes in carbon dioxide relative to water. On approach, the spacecraft observed frequent natural outbursts, a mean radius of 3.0 +/- 0.1 kilometers, smooth and rough terrain, scarps, and impact craters. A thermal map indicates a surface in equilibrium with sunlight.

Understanding how comets work--what drives their activity--is crucial to the use of comets in studying the early solar system. EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus, taking both images and spectra. Unlike large, relatively inactive nuclei, this nucleus is outgassing primarily because of CO(2), which drags chunks of ice out of the nucleus. It also shows substantial differences in the relative abundance of volatiles from various parts of the nucleus.

Background-Both psychological and physiological disturbances have been implicated in the aetiopathogenesis of irritable bowel syndrome (IBS). Aims-To investigate how the psychological factors act, and the involvement of infective and physiological factors. Methods-Consecutive patients hospitalised for gastroenteritis reported life events for the previous 12 months, and past illness experiences on standardised questionnaires. They also completed psychometric questionnaires for anxiety, neuroticism, somatisation, and hypochondriasis. In some patients, rectal biopsy specimens were obtained during the acute illness and at three months postinfection. Results-Ninety four patients completed all questionnaires: 22 patients were diagnosed with IBS after their gastroenteritis (IBS+), and 72 patients returned to normal bowel habits (IBS−). IBS+ patients reported more life events and had higher hypochondriasis scores than IBS− patients. The predictive value of the life event and hypochondriasis measures was highly significant and independent of anxiety, neuroticism, and somatisation scores, which were also elevated in IBS+ patients. Rectal biopsy specimens from 29 patients showed a chronic inflammatory response in both IBS+ and IBS− patients. Three months later, specimens from IBS+ patients continued to show increased chronic inflammatory cell counts but those from IBS− patients had returned to normal levels. IBS+ and IBS− patients exhibited rectal hypersensitivity and hyper-reactivity and rapid colonic transit compared with normal controls, but there were no significant diVerences between IBS+ and IBS− patients for these physiological measurements. Conclusion-Psychological factors most clearly predict the development of IBS symptoms after gastroenteritis but biological mechanisms also contribute towards the expression of symptoms. (Gut 1999;44:400-406)

There is rapidly evolving literature on water insecurity in the general adult population, but the role of water insecurity during the vulnerable periods of pregnancy and postpartum, or in the context of HIV, has been largely overlooked. Therefore, we conducted an exploratory study, using Go Along interviews, photo-elicitation interviews, and pile sorts with 40 pregnant and postpartum Kenyan women living in an area of high HIV prevalence. We sought to (1) describe their lived experiences of water acquisition, prioritisation, and use and (2) explore the consequences of water insecurity. The results suggest that water insecurity is particularly acute in this period, and impacts women in far-reaching and unexpected ways. We propose a broader conceptualisation of water insecurity to include consideration of the consequences of water insecurity for maternal and infant psychosocial and physical health, nutrition, and economic well-being.

To determine the effects of coronary angioplasty on coronary flow reserve (CFR), we studied 32 patients before and immediately after single-vessel coronary angioplasty and 31 patients evaluated late after angioplasty (7.5 + 1.2 months, mean + SEM). The geometry (percent area stenosis and minimal cross-sectional area) of each lesion was determined by quantitative coronary angiography (Brown/Dodge method) and the integrated optical density was measured by videodensitometry. CFR was measured with a No. 3F coronary Doppler catheter placed immediately proximal to the lesion and a maximally vasodilating dose of intracoronary papaverine. The translesional pressure gradient was obtained in all lesions before and immediately after angioplasty and in 18 of 31 vessels late after angioplasty. CFR immediately after angioplasty returned to normal levels (> 3.5 peak/resting velocity ratio) in 14 of 31 patients and was improved, although not normalized, in the remaining 17 patients. CFR immediately after dilation was not significantly correlated with any of the angiographic variables of arterial stenosis nor the resting pressure gradient. Moreover, the pressure gradient and absolute distal coronary pressure at peak hyperemia were not significantly different in vessels with normal and those with abnormal flow reserve immediately after dilation, suggesting that the residual stenosis did not significantly limit hyperemia. Late after angioplasty, however, a significant relationship emerged between CFR and all four indexes of residual arterial stenosis (percent area stenosis r = .70, p < .01; minimum arterial cross-sectional area r = .70, p < .01; integrated optical density r = .60, p < .01; and translesional pressure gradient r = .77, p < .01). Furthermore, in the absence of restenosis, CFR eventually normalized in all patients. These findings demonstrate that in one-half of patients there is a transient reduction in coronary flow reserve immediately after angioplasty. In the absence of restenosis, coronary flow reserve later normalizes. Consequently, measurements of coronary flow reserve immediately after angioplasty may not reflect the eventual success of the procedure in removing physiologic obstruction to coronary blood flow. Circulation 77, No. 4, 873-885, 1988. ALTHOUGH coronary angioplasty has been shown to increase coronary luminal cross-sectional area,1 reduce the translesional pressure gradient,2 ameliorate the symptoms of myocardial ischemia,3' 4and normalize previously positive noninvasive studies of provokable myocardial ischemia (e.g., exercise electrocardiographic,3' thallium-201 scintigraphic,4 and diastolic