Effects of drought on cattle production in sub-tropical environments

Tropical Animal Health and Production - The objective of the study was to assess farmer perceptions on effects of drought on cattle production in sub-tropical environments. Data was collected from...     

林分生长与产量模型系统研究综述

本文阐述了影响林分生长和产量的 5个因子 ,即立地指数、林分年龄、林分密度、生境类型和林分结构。介绍了林分水平、径级水平和单株木水平的林分生长和产量预测模型系统的一些代表性模型系统。还介绍了一些典型的生长和死亡模型。林木和林分是两级不同水平的生态系统。作者提出了建立以生态系统特性 (如系统的整体性、同时性、组成成分间交叉相关性等 )为基础的系统化模型。通过建立联立方程系统 ,用 3阶段最小二乘法拟合回归参数 ,可望提高林分生长和产量预测模型的真实性和估测精度     

Ruptured urinary bladder attributable to urethral compression by a haematoma after vertebral fracture in a bull

Background

In male cattle, rupture of the urinary bladder is usually associated with urethral obstruction by uroliths. Less common causes include urethral compression or stricture. This case report describes the findings in a young Limousion breeding bull with rupture of the urinary bladder because of urethral compression by a haematoma after coccygeal fracture.

Case presentation

The bull had been introduced into a 40-head Red-Holstein herd one week before being injured. One week after introduction to the herd, the bull had an acute onset of anorexia and he was referred to the clinic. There was marked abdominal distension, reduced skin turgor and enophthalmus. The serum concentration of urea and creatinine was increased. Ultrasonographic examination revealed severe ascites and abdominocentesis yielded clear yellow fluid with high urea and creatinine concentrations, which supported a diagnosis of uroperitoneum. The bull was euthanatized because of a poor prognosis. Postmortem examination revealed a comminuted fracture of the first two coccygeal vertebrae associated with a massive haematoma that obstructed entire pelvic cavity. The haematoma compressed the urethra thereby preventing outflow of urine, which resulted in a 5-cm tear ventrally at the neck of the bladder. It was assumed that the newly-introduced bull had sustained the vertebral fractures when he was mounted by a cow.

Conclusions

The present case study serves to expand the differential diagnosis of urinary bladder rupture. Therefore, in addition to obstructive urolithiasis, compression and stricture of the urethra might be considered in male cattle with uroperitoneum.     

Microscopic Particle Motions in Strongly Coupled Dusty Plasmas

The microscopic particle motions from the crystal to the disordered state of a dusty plasma with micrometer-sized silicon dioxide particle suspensions in a radio-frequency glow discharge system were studied through an optical microimaging system. Small-amplitude random motion around the lattice sites of the crystal state, relative domain motion with varying boundaries, cooperative hopping in the liquid state, and highly disordered motion with increasing radio-frequency power were observed. Chaotic states with different spatial scales under the coherent and stochastic coupling between dust particles and self-organized background plasma fluctuations were also demonstrated.     

A genomic regulatory network for development

Development of the body plan is controlled by large networks of regulatory genes. A gene regulatory network that controls the specification of endoderm and mesoderm in the sea urchin embryo is summarized here. The network was derived from large-scale perturbation analyses, in combination with computational methodologies, genomic data, cis-regulatory analysis, and molecular embryology. The network contains over 40 genes at present, and each node can be directly verified at the DNA sequence level by cis-regulatory analysis. Its architecture reveals specific and general aspects of development, such as how given cells generate their ordained fates in the embryo and why the process moves inexorably forward in developmental time.     

C-cadherin ectodomain structure and implications for cell adhesion mechanisms

Cadherins are transmembrane proteins that mediate adhesion between cells in the solid tissues of animals. Here we present the 3.1 angstrom resolution crystal structure of the whole, functional extracellular domain from C-cadherin, a representative "classical" cadherin. The structure suggests a molecular mechanism for adhesion between cells by classical cadherins, and it provides a new framework for understanding both cis (same cell) and trans (juxtaposed cell) cadherin interactions. The trans adhesive interface is a twofold symmetric interaction defined by a conserved tryptophan side chain at the membrane-distal end of a cadherin molecule from one cell, which inserts into a hydrophobic pocket at the membrane-distal end of a cadherin molecule from the opposing cell.