Glassy Vortex State in a Two-Dimensional Disordered XY-Model

The two-dimensional XY-model with random phase-shifts on bonds is studied. The analysis is based on a renormalization group for the replicated system. The model is shown to have an ordered phase with quasi long-range order. This ordered phase consists of a glass-like region at lower temperatures and of a non-glassy region at higher temperatures. The transition from the disordered phase into the ordered phase is not reentrant and is of a new universality class at zero temperature. In contrast to previous approaches the disorder strength is found to be renormalized to larger values. Several correlation functions are calculated for the ordered phase. They allow to identify not only the transition into the glassy phase but also an additional crossover line, where the disconnected vortex correlation changes its behavior on large scales non-analytically. The renormalization group approach yields the glassy features without a breaking of replica symmetry.Comment: latex 12 pages with 3 figures, using epsf.sty and multicol.st

Length of Barrett's oesophagus: an important factor in the development of dysplasia and adenocarcinoma.

In a 15 year prospective study of endoscopic surveillance of columnar lined oesophagus, 102 patients with a mean follow up of 54 (12.5) months and total follow up of 462 years have been evaluated. Of all the sets of biopsies taken, 59 in 21 patients were found to exhibit dysplasia or carcinoma. Four male patients had carcinoma of the oesophagus, indicating a 30 times increased risk of development of adenocarcinoma in columnar lined oesophagus. The length of columnar lined oesophagus in subjects with dysplasia was significantly longer as compared with the whole group (p = 0.01) and when compared with the patients without dysplasia (p = 0.005). None of the patients with dysplasia had a columnar lined oesophagus of less than 8 cm. Length of columnar lined oesophagus therefore seems to be a significant risk factor in the development of dysplasia and subsequent carcinoma and intensive follow up of patients with columnar lined oesophagus greater than 8 cm in length is recommended

The design of artificial nestboxes for the study of secondary hole-nesting birds: A review of methodological inconsistencies and potential biases

The widespread use of artificial nestboxes has led to significant advances in our knowledge of the ecology, behaviour and physiology of cavity nesting birds, especially small passerines. Nestboxes have made it easier to perform routine monitoring and experimental manipulation of eggs or nestlings, and also repeatedly to capture, identify and manipulate the parents. However, when comparing results across study sites the use of nestboxes may also introduce a potentially significant confounding variable in the form of differences in nestbox design amongst studies, such as their physical dimensions, placement height, and the way in which they are constructed and maintained. However, the use of nestboxes may also introduce an unconsidered and potentially significant confounding variable due to differences in nestbox design amongst studies, such as their physical dimensions, placement height, and the way in which they are constructed and maintained. Here we review to what extent the characteristics of artificial nestboxes (e.g. size, shape, construction material, colour) are documented in the ‘methods’ sections of publications involving hole-nesting passerine birds using natural or excavated cavities or artificial nestboxes for reproduction and roosting. Despite explicit previous recommendations that authors describe in detail the characteristics of the nestboxes used, we found that the description of nestbox characteristics in most recent publications remains poor and insufficient. We therefore list the types of descriptive data that should be included in the methods sections of relevant manuscripts and justify this by discussing how variation in nestbox characteristics can affect or confound conclusions from nestbox studies. We also propose several recommendations to improve the reliability and usefulness of research based on long-term studies of any secondary hole-nesting species using artificial nestboxes for breeding or roosting.