Application of large eddy interaction model to channel flow

A procedure utilizing an expansion of proper orthogonal functions (or modes) to predict a fully developed flow in channel is derived. To examine numerical and conceptual difficulties, preliminary computations are performed with assigned mean velocity, and turbulence is expressed with only the first mode. The nonlinear interactions of the components of the first mode are treated specifically, with the influence of higher modes neglected; this treatment required adjustment of the skewness and effective Reynolds number to assure energy equilibrium of the first mode. Computational results show that the first mode possesses the structural character similar to that of the entire flow

Small bowel MRI in adult patients: not just Crohn’s disease—a tutorial

To provide an overview of less well-known small bowel and mesenteric diseases found at small bowel magnetic resonance (MR) enterography/enteroclysis and to review the imaging findings. MR enterography and enteroclysis are important techniques for evaluation of small bowel diseases. In most centres these techniques are primarily used in Crohn's disease, and most radiologists are familiar with these MRI findings. However, the knowledge of findings in other diseases is often sparse, including diseases that may cause similar clinical symptoms to those of Crohn's disease. We present a spectrum of less common and less well-known bowel and mesenteric diseases (e.g. internal hernia, intussusception, neuroendocrine tumour) from our small bowel MR database of over 2,000 cases. These diseases can be found in patients referred for bowel obstruction, abdominal pain or rectal blood loss. Further, in patients with (or suspected to have) Crohn's disease, some of these diseases (e.g. neuroendocrine tumour, familial Mediterranean fever) may mislead radiologists to erroneously diagnose active Crohn's disease. Radiologists should be familiar with diseases affecting the small bowel other than Crohn's disease, including diseases that may mimic Crohn's diseas

JPN Guidelines for the management of acute pancreatitis: epidemiology, etiology, natural history, and outcome predictors in acute pancreatitis

Acute pancreatitis is a common disease with an annual incidence of between 5 and 80 people per 100 000 of the population. The two major etiological factors responsible for acute pancreatitis are alcohol and cholelithiasis (gallstones). The proportion of patients with pancreatitis caused by alcohol or gallstones varies markedly in different countries and regions. The incidence of acute alcoholic pancreatitis is considered to be associated with high alcohol consumption. Although the incidence of alcoholic pancreatitis is much higher in men than in women, there is no difference in sexes in the risk involved after adjusting for alcohol intake. Other risk factors include endoscopic retrograde cholangiopancreatography, surgery, therapeutic drugs, HIV infection, hyperlipidemia, and biliary tract anomalies. Idiopathic acute pancreatitis is defined as acute pancreatitis in which the etiological factor cannot be specified. However, several studies have suggested that this entity includes cases caused by other specific disorders such as microlithiasis. Acute pancreatitis is a potentially fatal disease with an overall mortality of 2.1%–7.8%. The outcome of acute pancreatitis is determined by two factors that reflect the severity of the illness: organ failure and pancreatic necrosis. About half of the deaths in patients with acute pancreatitis occur within the first 1–2 weeks and are mainly attributable to multiple organ dysfunction syndrome (MODS). Depending on patient selection, necrotizing pancreatitis develops in approximately 10%–20% of patients and the mortality is high, ranging from 14% to 25% of these patients. Infected pancreatic necrosis develops in 30%–40% of patients with necrotizing pancreatitis and the incidence of MODS in such patients is high. The recurrence rate of acute pancreatitis is relatively high: almost half the patients with acute alcoholic pancreatitis experience a recurrence. When the gallstones are not treated, the risk of recurrence in gallstone pancreatitis ranges from 32% to 61%. After recovering from acute pancreatitis, about one-third to one-half of acute pancreatitis patients develop functional disorders, such as diabetes mellitus and fatty stool; the incidence of chronic pancreatitis after acute pancreatitis ranges from 3% to 13%. Nevertheless, many reports have shown that most patients who recover from acute pancreatitis regain good general health and return to their usual daily routine. Some authors have emphasized that endocrine function disorders are a common complication after severe acute pancreatitis has been treated by pancreatic resection

Topographic representation of the pharyngoesophageal segment during swallowing

Motility of the pharyngoesophageal segment (PES) was monitored by cineradiography (50 frames a second) during barium swallow and analyzed by a computerized topographic mapping of sagittal wall motion. Through measurement of wall displacement on 20 consecutive levels of the PES, distention, contraction, and peristalsis were studied. Topographic mapping of three patients with normal PES motility, delayed opening of the cricopharyngeus, and incomplete opening of the cricopharyngeus, was performed. These topographic mappings show that "narrowing" at the level of the cricopharyngeus reflects expansion of the hypopharynx and cervical esophagus around the cricopharyngeus, rather than a true narrowing. In addition, analysis of wall motion demonstrated that abnormality of the circopharyngeus is often associated with abnormality of wall motion in the adjoining hypopharynx and cervical esophagus. Thus, topographic mapping of the cricopharyngeus is of value because it enables detailed analysis of wall motion during various pathologic conditions

Duodenitis: a reliable radiologic diagnosis?

The authors performed a retrospective study of 50 patients with endoscopically diagnosed duodenitis who had undergone double-contrast upper gastrointestinal (GI) examinations. Duodenitis was diagnosed on the original radiographic reports in six of 37 patients (16%) with mild-to-moderate duodenitis, five of 13 patients (38%) with severe duodenitis, and 11 of 50 patients (22%) with all grades of duodenitis on endoscopy. Subsequent analysis of the films revealed one or more radiologic signs of duodenitis (including folds more than 4 mm in thickness, mucosal nodularity, bulbar deformity, and erosions) in 18 of 37 patients (49%) with mild-to-moderate duodenitis, eight of 13 patients (62%) with severe duodenitis, and 26 of 50 patients (52%) with all grades of duodenitis on endoscopy. In a separate part of the study, the authors identified another 20 patients with radiographically diagnosed duodenitis who had undergone endoscopic examinations. Nine of those 20 patients (45%) had duodenitis on endoscopy. Subsequent analysis of the films revealed one or more signs of duodenitis in 17 patients from this group. Nine of the latter patients (53%) had duodenitis on endoscopy. Using established radiologic criteria for duodenitis, our rate of false-positive and false-negative radiologic diagnoses still was about 50%. Thus, the double-contrast upper GI examination is a relatively unreliable technique for diagnosing duodenitis