Influence of food quality and quantity on the growth and development of Crassostrea gigas larvae: a modeling approach

A biochemically based model was developed to simulate the growth, development and metamorphosis of larvae of the Pacific oyster, Crassostrea gigas. The model is unique in that it (1) defines larvae in terms of their protein, neutral lipid, polar lipid, carbohydrate and ash content; (2) tracks weight separately from length to follow larval condition index and (3) includes genetic variation in growth efficiency and egg quality to better simulate cohort population dynamics. The model includes parameterizations for larval filtration, ingestion and respiration that determine growth rate and processes controlling larval mortality and metamorphosis. Changes in tissue composition occur as the larva grows and in response to the biochemical composition of the food.

The simulations show that genetically determined variations in growth efficiency produce significant changes in larval survival and success at metamorphosis. Larvae with low growth efficiency are successful under a much narrower range of culture conditions than larvae with high growth efficiency. The impact of low growth efficiency is primarily controlled by the ability of larvae to store lipid for metamorphosis. Culture conditions that provide increased dietary lipid counterweigh low growth efficiency. Changes in food quantity and quality had little effect on size at metamorphosis. On the other hand, larval life span and success rate at metamorphosis varied over a wide range depending upon the conditions of the simulation. Food quality and food availability both influence larval life span and, hence, larval survival. As ingestion rate decreases, larval life span increases and cohort survival declines. Increased lipid or decreased protein in the diet improves cohort survival. Changes in carbohydrate content are less influential. If cohort success is significantly affected by mortality during larval life rather than success at metamorphosis, the influence of food quality becomes more complex. The range of food compositions yielding high survival is restricted by a balance between improved success at metamorphosis obtained by increased lipid storage and the shortening of larval life span as a result of more rapid growth, a function of protein availability. These simulations illustrate the strength and utility of numerical models for evaluating and designing hatchery protocols for optimizing yield of C. gigas larvae.     

Forestry on the Scottish Border Hills

The physical conditions of the Border hills are briefly described.The general problems of both private and State-owned woodlandsare discussed; in particular those of afforestation of peatareas and the danger of windblow. Future management and regenerationis considered and the probable methods to be used are suggested.     

Use of animation-enhanced video clips for teaching abnormal breathing patterns

The ability to characterize disease of the respiratory tract accurately based on breathing pattern is helpful for the development of differential diagnoses and an efficient diagnostic plan and critical for the stabilization of patients in respiratory distress. Veterinary students do not have sufficient clinical experience to observe personally all types of respiratory diseases and their resultant abnormal breathing patterns. We developed a teaching tool, the animated breathing pattern videotape (ABV), to fill this gap. The ABV is a collection of video clips of small animal patients with normal and abnormal breathing patterns on a conventional videotape of approximately 20 minutes duration. Each video clip is shown for 20 to 40 seconds, followed by the same clip with superimposed animation of rib and diaphragm motion, followed by the initial clip again, without overlying animation. The ABV has since been used in teaching third-year veterinary students, interns, residents, practicing veterinarians, and veterinary technicians. Student evaluations and responses to questionnaires by interns, residents, practicing veterinarians, veterinary technicians, and peer reviewers have been uniformly positive.     

Demographic, clinical, and radiographic features of bronchiectasis in dogs: 316 cases (1988-2000)

OBJECTIVE: To determine demographic, clinical, and radiographic features of bronchiectasis in dogs. DESIGN: Retrospective study. ANIMALS: 289 dogs identified through the Veterinary Medical Database (VMDB) and 27 dogs examined at the North Carolina State University Veterinary Teaching Hospital. PROCEDURE: Demographic characteristics of dogs identified through the VMDB were compared with characteristics of the entire population of dogs entered in the VMDB. Medical records of dogs examined at the teaching hospital were reviewed; the diagnosis was confirmed through review of thoracic radiographs. RESULTS: Analysis of data from the VMDB indicated that American Cocker Spaniels, West Highland White Terriers, Miniature Poodles, Siberian Huskies, English Springer Spaniels, and dogs > 10 years old had an increased risk of bronchiectasis. Among dogs examined at the teaching hospital, coughing was the most common clinical sign. There was evidence for excessive airway mucus but not hemorrhage. A variety of bacterial organisms were isolated from tracheal wash and bronchoalveolar lavage samples. On thoracic radiographs, cylindrical bronchiectasis, generalized disease, and right cranial lung lobe involvement were most common. Seven of 14 dogs for which follow-up radiographs were available did not have any progression of radiographic lesions. Median duration of clinical signs prior to diagnosis of bronchiectasis was 9 months (range, 1 day to 10 years). Median survival time was 16 months (range, 2 days to 72 months). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that despite substantial clinical abnormalities, dogs with bronchiectasis may survive for years. Certain purebred dogs and older dogs may have an increased risk of developing bronchiectasis.     

Light Use Efficiency and Woody Biomass Production of Poplar and Willow

Stands of clonal Salix viminalis (in 1985) and Populus trichocarpa(in 1986) were grown for one growing season from cuttings incontainers, at 0.3 m spacing, supplied with trickle irrigationand nutrients. Woody biomass production (B_w) in the first yearwas analysed as the product of the proportion of dry matterpartitioned to wood ({macron}), the seasonal mean efficiencywith which intercepted light was used to produce dry matter({macron}), the mean fraction of incident light interceptedby the canopies (f{macron}), and the amount of incoming solarradiation over the season (A). Thus, Bw = {macron}f{macron}{macron}A. For Salix, B_w=10 t ha^–1y^–1, while for Populus, B_w= 5 t ha^–1y^–1, mainly because of differences in{macron} and f{macron}. The Populus partitioned more dry matterto roots (and correspondingly less to stems) and interceptedless light over the growing season. The Salix and Populus cloneshad surprisingly similar ({macron}) values, namely 1. 58 and1. 50 g MJ^–1, respectively (based on total dry matterand total solar radiation), which are very like the {macron}values measured on C₃ agricultural crops in Britain. Also, theSalix and Populus clones produced canopies with similar lightextinction coefficients and hence similar relationships betweenfractional interception and leaf area index.     

Canine diabetes mellitus: a retrospective survey

This paper describes the results of a retrospective survey of 43 cases of canine diabetes mellitus. The epidemiological data were in general agreement with previous surveys. Blood glucose, serum alkaline phosphatase, serum alanine aminotransferase, blood urea and serum cholesterol levels measured before starting treatment were found to be of limited value in forming a pre-treatment prognosis, although markedly raised values were a poor prognostic sign.     

Two-dimensional nanosheets produced by liquid exfoliation of layered materials

If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exfoliated into individual layers. By blending this material with suspensions of other nanomaterials or polymer solutions, we can prepare hybrid dispersions or composites, which can be cast into films. We show that WS(2) and MoS(2) effectively reinforce polymers, whereas WS(2)/carbon nanotube hybrid films have high conductivity, leading to promising thermoelectric properties.