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The solid, central part of a comet--its nucleus--is subject to destructive processes, which cause nuclei to split at a rate of about 0.01 per year per comet. These destructive events are due to a range of possible thermophysical effects; however, the geophysical expressions of these effects are unknown. Separately, over two-thirds of comet nuclei that have been imaged at high resolution show bilobate shapes, including the nucleus of comet 67P/Churyumov-Gerasimenko (67P), visited by the Rosetta spacecraft. Analysis of the Rosetta observations suggests that 67P's components were brought together at low speed after their separate formation. Here, we study the structure and dynamics of 67P's nucleus. We find that sublimation torques have caused the nucleus to spin up in the past to form the large cracks observed on its neck. However, the chaotic evolution of its spin state has so far forestalled its splitting, although it should eventually reach a rapid enough spin rate to do so. Once this occurs, the separated components will be unable to escape each other; they will orbit each other for a time, ultimately undergoing a low-speed merger that will result in a new bilobate configuration. The components of four other imaged bilobate nuclei have volume ratios that are consistent with a similar reconfiguration cycle, pointing to such cycles as a fundamental process in the evolution of short-period comet nuclei. It has been shown that comets were not strong contributors to the so-called late heavy bombardment about 4 billion years ago. The reconfiguration process suggested here would preferentially decimate comet nuclei during migration to the inner solar system, perhaps explaining this lack of a substantial cometary flux.

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OBJECTIVE: We aimed to demonstrate the effect of continuous or bolus nasogastric feeding on gastric emptying, small bowel water content, and splanchnic blood flow measured by magnetic resonance imaging (MRI) in the context of changes in plasma gastrointestinal hormone secretion. BACKGROUND: Nasogastric/nasoenteral tube feeding is often complicated by diarrhea but the contribution of feeding strategy to the etiology is unclear. METHODS: Twelve healthy adult male participants who underwent nasogastric intubation before a baseline MRI scan, received 400  mL of Resource Energy (Nestle) as a bolus over 5 minutes or continuously over 4  hours via pump in this randomized crossover study. Changes in gastric volume, small bowel water content, and superior mesenteric artery blood flow and velocity were measured over 4  hours using MRI and blood glucose and plasma concentrations of insulin, peptide YY, and ghrelin were assayed every 30 minutes. RESULTS: Bolus nasogastric feeding led to significant elevations in gastric volume (P < 0.0001), superior mesenteric artery blood flow (P < 0.0001), and velocity (P = 0.0011) compared with continuous feeding. Both types of feeding reduced small bowel water content, although there was an increase in small bowel water content with bolus feeding after 90 minutes (P < 0.0068). Similarly, both types of feeding led to a fall in plasma ghrelin concentration although this fall was greater with bolus feeding (P < 0.0001). Bolus feeding also led to an increase in concentrations of insulin (P = 0.0024) and peptide YY (P < 0.0001), not seen with continuous feeding. CONCLUSION: Continuous nasogastric feeding does not increase small bowel water content, thus fluid flux within the small bowel is not a major contributor to the etiology of tube feeding-related diarrhea.

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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.

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Pseudoaneurysms related to the superior mesenteric artery (SMA) are a recognised complication of trauma to the vessel, and successful treatment with stenting has been previously described. We report the case of a patient who presented with obstruction of the fourth part of the duodenum secondary to a traumatic pseudoaneurysm, a hitherto unreported variant of superior mesenteric artery syndrome. Exclusion of the pseudoaneurysm and relief of the duodenal obstruction were simultaneously achieved by placement of a covered stent.

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OBJECTIVES: We assessed the economic and clinical implications of systematic long-term nutrition team follow-up of patients after percutaneous endoscopic gastrostomy. METHODS: We designed a prospective, randomized, controlled, single-blind trial in a large district hospital and its catchment area. All adult patients referred for a gastrostomy were eligible and randomized into two groups. The intervention group had regular follow-up by the nutrition team (weekly in hospital, monthly after discharge) with appropriate support and advice for patient, carer, and primary care professionals. The control group had no specific nutrition team input (as is often current practice). Endpoints to the study were 12 mo, elective removal of tube, or death. The primary outcome was total health care costs. Secondary outcomes were complications, length of stay, readmissions, nutritional status, and quality of life. RESULTS: One hundred twelve patients were recruited. Eleven died before the start of the trial, leaving 47 in the intervention group and 54 in the control group. They were well matched for age, sex, and underlying diagnosis. Overall, the health care costs were 13,330 sterlings per patient in the intervention group compared with 16,858 pound sterlings in the control group (two-tailed, P = 0.27), a saving of 21% per patient. The intervention group had shorter lengths of stay, fewer and briefer readmissions, earlier removal of gastrostomy (where appropriate), shorter duration of feeding, and less demand for general practitioners and district nurse inputs. Nutritional status and quality of life were similar. CONCLUSIONS: Regular systematic nutrition team follow-up for gastrostomy-fed patients does not increase costs and may improve quality of care.

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Irritable bowel syndrome (IBS) is a very common problem affecting 10% of the population at some time. Its cause and pathogenesis, however, remain poorly understood. Diagnosis is usually straightforward and detailed investigations are only required when the presentation is atypical. Treating IBS is always a challenge. The concerns and expectations of the patient must be met, along with any associated psychosocial issues. Medication on its own without addressing all of these issues is usually unsuccessful.

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Gastro-oesophageal reflux disease (GORD) is a common disease that is likely to increase in prevalence as the population becomes steadily more obese. Although generally benign reflux can, if untreated, lead to severe complications. This article describes the symptoms and diagnosis of acid reflux and GORD, and reviews currently available treatments ranging from lifestyle modification to surgery.

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Patients with intestinal failure are at risk for malnutrition and its associated adverse consequences. In many of these patients it is not possible to feed via the gastrointestinal tract, and nutrients must be provided directly into the bloodstream. For some patients with irreversible intestinal failure, this is a lifelong requirement. Parenteral nutrient solutions may be tailored specifically to individual requirements and are usually administered directly into a central vein using an indwelling catheter. Serious complications related to both the indwelling catheter and metabolic consequences of the nutritional support may occur. A team approach to the provision and monitoring of parenteral nutrition in intestinal failure produces the best results.