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PubMed2000

Bar Dissolution in Prolate Halos.

The time evolution of barred structures is examined under the influence of the external forces exerted by a spherical halo and by prolate halos. In particular, galaxy disks are placed in the plane including the major axis of prolate halos, whose configuration is often found in cosmological simulations. N-body disks in fixed external halo fields are simulated, so that bars are formed via dynamical instability. In the subsequent evolution, the bars in prolate halos dissolve gradually with time, while the bar pattern in a spherical halo remains almost unchanged to the end of the simulation. The decay times of the bars suggest that they can be destroyed in a time smaller than a Hubble time. Our results indicate that this dissolution process could occur in real barred galaxies, if they are surrounded by massive dark prolate halos, and the configuration adopted here is not unusual from the viewpoint of galaxy formation. For a prolate halo model, an additional simulation that is restricted to two-dimensional in-plane motions has also ended up with similar bar dissolution. This means that the vertical motions of disk stars do not play an essential role in the bar dissolution demonstrated here.

Journal Article↗

PubMedDate not supplied

Prevalence of primary sclerosing cholangitis and other liver diseases in Japanese patients with chronic ulcerative colitis.

An association between primary sclerosing cholangitis (PSC) and chronic ulcerative colitis (CUC) is well known in Western countries, but there have been no reports on this association in Japan. We reviewed 163 consecutive CUC patients (91 males and 72 females) diagnosed from 1984 to 1990 at Tokyo Women's Medical College. Abnormal liver function tests were found in 42 patients with CUC (25.8%), but chronic liver disease was only diagnosed in seven patients (4.3%). Among these seven patients, there were four with PSC, one with small-duct PSC, one with transfusion-associated chronic hepatitis and one with Type B liver cirrhosis. No relationship was found between the documented colonic manifestations of CUC and the presence of PSC. The four PSC patients did not have a longer history of CUC at the time of diagnosis of PSC than CUC patients without PSC. At the time of PSC diagnosis, two patients were asymptomatic, one presented with right upper quadrant pain, and the other had fatigue. Three patients were diagnosed as having CUC before the onset of PSC (range 2-13 years), and the other patient had both diseases simultaneously. All four had a good prognosis. Thus PSC was the most common chronic liver disease associated with CUC in our series, and it was present in all our CUC patients with alkaline phosphatase levels exceeding twice the upper limit of normal and mild transaminase elevation.

Adolescent↗