Gastric impaction associated with displacement and volvulus of the large colon in seven mature horses

Gastric impaction associated with large colon volvulus (LCV) was identified in seven horses. Right dorsal displacement of the large colon and suspected nephrosplenic entrapment was identified in 2 of the 7 horses as well as LCV with concurrent gastric impaction. All horses underwent surgery for LCV and none survived. Five horses died or were subjected to euthanasia intraoperatively or in recovery. One horse was subjected to euthanasia post operatively due to persistent gastric reflux, following resolution of the gastric impaction. One horse was subjected to euthanasia post operatively due to a suspected gastric rupture, which was confirmed on post mortem examination. It is hypothesised that a large mass in the cranial abdomen, such as a gastric impaction may disrupt the normal anatomical large colon alignment or may cause colonic motility or microbiota alterations, and thus increase the risk of large colon displacement and volvulus.     

Mathematics and complex systems

Contemporary researchers strive to understand complex physical phenomena that involve many constituents, may be influenced by numerous forces, and may exhibit unexpected or emergent behavior. Often such "complex systems" are macroscopic manifestations of other systems that exhibit their own complex behavior and obey more elemental laws. This article proposes that areas of mathematics, even ones based on simple axiomatic foundations, have discernible layers, entirely unexpected "macroscopic" outcomes, and both mathematical and physical ramifications profoundly beyond their historical beginnings. In a larger sense, the study of mathematics itself, which is increasingly surpassing the capacity of researchers to verify "by hand," may be the ultimate complex system.     

Materials with negative compressibilities in one or more dimensions

Rare crystal phases that expand in one or more dimensions when hydrostatically compressed are identified and shown to have negative Poisson's ratios. Some of these crystals (i) decrease volume and expand in two dimensions when stretched in a particular direction and (ii) increase surface area when hydrostatically compressed. Possible mechanisms for achieving such negative linear and area compressibilities are described for single crystals and composites, and sensor applications are proposed. Materials with these properties may be used to fabricate porous solids that either expand in all directions when hydrostatically compressed with a penetrating fluid or behave as if they are incompressible.     

Annotations file for RDA184Page: 1Author/editor: is short title acceptable?Reproductive and Endocrine Changes in Dairy Cows Given GnRH at Different Intervals Postpartum

Contents
The reproductive organs of 91 cows in the university herd were palpated at least twice per week from 12 to 53 days postpartum (PP). Based upon uterine and cervical involution and tone, ovarian condition and fluid discharge at 12 to 18 days PP they were classified as normal or abnormal. Within each group they were randomly assigned to receive either saline or 100 μg of GnRH at 12 to 18 days or 100 μg of GnRH at 22 to 28 days PP. Milk samples were taken for progesterone determinations three times per week until the first breeding or up to 90 days PP. A subset of 23 cows completed a frequent blood sampling programme at 0 h (just prior to treatment), 1, 2, 4, 8 and 12 h later and every 12 h for 15 days following treatment. Values for milk and serum progesterone in samples taken during the same time period were highly correlated, r = 0.90, and were consistent with ovarian changes detected by palpation. Cows classified as normal initially continued to be normal, and GnRH had little effect. In the abnormal groups of cows at 28 days PP, 41% of the saline group and 77% of those treated with GnRH at 12 to 18 days PP had fully involuted uteri. Early treatment of abnormal cows with GnRH improved the reproductive efficiency, resulting in 95 days open compared with 129 days for saline-treated abnormals. In conclusion, treatment with GnRH was effective in hastening the return to normal of cows classified initially as abnormal, and appears to be cost effective in maintaining an optimal calving interval.