Morphometrical, behavioural and chemical changes during growth and starvation of herring and plaice larvae.

Growth rates of herring (Clupea harengus) and plaice (Pleuronectes platessa) larvae were 0.22 and 0.16 mm/day respectively. The slope of the length-dry weight line for plaice larvae was 3.92. That for herring larvae was 4.57, which remained constant throughout starvation, although the intercepts decreased. If wet weights were used the slopes decreased. Relative condition factors were used to estimate nutritive condition over a wide size range. Condition factors based on length and weight were not very good for estimating nutritive condition, due to concurrent losses of length and weight. The ratio of eye to head height rapidly increased during starvation due to head shrinkage. The sinking rate of herring larvae in sea water decreased from hatching to the end of the yolk sac stage but increased with further growth. Newly hatched plaice larvae were positively buoyant, but their sinking rate increased with development. In both species the rate decreased during starvation. This was suggested to be a mechanism of energy conservation. Water content was inversely related to the sinking rate, but other body components also influenced it. Water provided the major upward vector, followed by fat; protein was responsible for the downward force. The decrease in sinking rate during starvation was partially due to the increasing percentage of water, but the largest proportion was from nitrogen catabolism. The days of starvation to reach irreversible starvation increased during development; the rate of increase was greater in plaice. Over 50j6 of the life span of herring and plaice starved from the end of the yolk sac stage was beyond irreversible starvation. Ontogenetic changes in chemical composition were dependent upon larval size rather than age. Percent water decreased throughout development from the end of the yolk sac stage. In the period of initial post-hatching growth (up to 20 mm in herring and stage 2 in plaice) nitrogen and carbohydrate were laid down faster than triglyceride, suggesting that it was advantageous to the larvae to convert food largely into growth rather than simultaneously accumulating energy stores. During starvation percent water increased about 4$ above the unstarved level; percent ash also increased. The percentage of triglyceride, carbohydrate, and carbon decreased in both species, as did nitrogen in plaice. In herring the percentage of nitrogen did not change throughout starvation, although the actual amount decreased. The C/N ratio decreased in starved herring, but it did not show a consistent pattern in plaice. It was suggested that the use of nitrogen throughout starvation could be an adaptation by pelagic marine larvae to the planktonic environment, since nitrogen catabolism was responsible for their decreasing sinking rate. Herring egg composition from different females was related to hatching success. The size of the larvae at the end of the yolk sac stage was compared to their chemical composition. Survival and chemical composition of 100 day-old herring and 50 day-old plaice larvae were altered after 20 days of feeding on diets of Artemi a . rotifers, or plankton, but larval length was not 'affected. The size of the larval fat store was influenced by the amount of dietary fat. Herring larvae started feeding on rotifers 5 days post-hatching, 2 days earlier than on a mixture of barnacle and shrimp brine/nauplii and plankton. By 28 days the rotifer-feeders were significantly larger. 20 mm herring larvae ate 190 rotifers/ larvae/day

Reply to: Synoptic operative reports for quality improvement in pediatric cancer care

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145496/1/pbc27277.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145496/2/pbc27277_am.pd

Cohomology theory of groups

This paper is concerned with the development of some elementary cohomology theory of groups presented by Eilenberg and MacLane and with cohomology of group extensions as presented by Kurosh. An outline of the basic theory of group extensions is presented

Personnel Launch System (PLS) study

NASA is currently studying a personnel launch system (PLS) approach to help satisfy the crew rotation requirements for the Space Station Freedom. Several concepts from low L/D capsules to lifting body vehicles are being examined in a series of studies as a potential augmentation to the Space Shuttle launch system. Rockwell International Corporation, under contract to NASA, analyzed a lifting body concept to determine whether the lifting body class of vehicles is appropriate for the PLS function. The results of the study are given

The Use and Content of Formal Rating Systems in Angel Group Investment Initial Screening Stages

We examined the formal screening process of thirty-eight Angel Investment Groups. Within our sample, over eighty percent of the Angel Investment Groups used a committee of members to perform the initial screening of submitted business plans, while the remaining relied upon the managing partner or senior director to perform the initial screening. Of the Angel Investment Groups that use a screening committee, approximately half also employed a formal scoring system. With respect to the important dimensions used in the scoring systems, the quality/experience of the management team and the competitive advantage of the firm's product or service, including strength of intellectual property protection, were consistently the most common dimensions seen in the scoring systems examined. A content analysis of the scoring sheets was also performed in order to determine the various sub-topics and linguistic themes associated with Angel rating systems

Advanced Manned Launch System (AMLS) study

To assure national leadership in space operations and exploration in the future, NASA must be able to provide cost effective and operationally efficient space transportation. Several NASA studies and the joint NASA/DoD Space Transportation Architecture Studies (STAS) have shown the need for a multi-vehicle space transportation system with designs driven by enhanced operations and low costs. NASA is currently studying an advanced manned launch system (AMLS) approach to transport crew and cargo to the Space Station Freedom. Several single and multiple stage systems from air-breathing to all-rocket concepts are being examined in a series of studies potential replacements for the Space Shuttle launch system in the 2000-2010 time frame. Rockwell International Corporation, under contract to the NASA Langley Research Center, has analyzed a two-stage all-rocket concept to determine whether this class of vehicles is appropriate for the AMLS function. The results of the pre-phase A study are discussed

Notification of pesticide poisoning in the western Cape, 1987 - 1991

There is a paucity of data on pesticide-related morbidity and mortality in South Africa. A review of notifications to the western Cape office of the Department of National Health and Population Development from 1987 to 1991 was undertaken to describe the epidemiological profile of pesticide poisoning in the region. Two hundred and twenty five cases of pesticide poisoning were identified, of which the majority were from rural areas. Farmers, farm workers and their families were most frequently involved in poisoning events, which included accidents arising outside of workplace production (44%), self-inflicted injury (35%) and direct occupational contamination (11%). Farm pesticide stores were the most frequent source of pesticide and a seasonal variation in the trend of poisoning events could be discerned; this corresponded to agricultural spraying practices in the region. The mortality rate was significantly higher among those with self-inflicted injury, particularly farm workers. A concurrent review of hospital admissions for 1991 found that 78% of cases had not been notified. In view of the key role of surveillance in reducing pesticide-related morbidity and mortality, a call is made to improve notification of pesticide poisoning so as to facilitate control of an important potential public health problem

Rate theory for correlated processes: Double-jumps in adatom diffusion

We study the rate of activated motion over multiple barriers, in particular the correlated double-jump of an adatom diffusing on a missing-row reconstructed Platinum (110) surface. We develop a Transition Path Theory, showing that the activation energy is given by the minimum-energy trajectory which succeeds in the double-jump. We explicitly calculate this trajectory within an effective-medium molecular dynamics simulation. A cusp in the acceptance region leads to a sqrt{T} prefactor for the activated rate of double-jumps. Theory and numerical results agree

Fear Memory Retrieval Is Associated With a Reduction in AMPA Receptor Density at Thalamic to Amygdala Intercalated Cell Synapses

The amygdala plays a crucial role in attaching emotional significance to environmental cues. Its intercalated cell masses (ITC) are tight clusters of GABAergic neurons, which are distributed around the basolateral amygdala complex. Distinct ITC clusters are involved in the acquisition and extinction of conditioned fear responses. Previously, we have shown that fear memory retrieval reduces the AMPA/NMDA ratio at thalamic afferents to ITC neurons within the dorsal medio-paracapsular cluster. Here, we investigate the molecular mechanisms underlying the fear-mediated reduction in the AMPA/NMDA ratio at these synapses and, in particular, whether specific changes in the synaptic density of AMPA receptors underlie the observed change. To this aim, we used a detergent-digested freeze-fracture replica immunolabeling technique (FRIL) approach that enables to visualize the spatial distribution of intrasynaptic AMPA receptors at high resolution. AMPA receptors were detected using an antibody raised against an epitope common to all AMPA subunits. To visualize thalamic inputs, we virally transduced the posterior thalamic complex with Channelrhodopsin 2-YFP, which is anterogradely transported along axons. Using face-matched replica, we confirmed that the postsynaptic elements were ITC neurons due to their prominent expression of μ-opioid receptors. With this approach, we show that, following auditory fear conditioning in mice, the formation and retrieval of fear memory is linked to a significant reduction in the density of AMPA receptors, particularly at spine synapses formed by inputs of the posterior intralaminar thalamic and medial geniculate nuclei onto identified ITC neurons. Our study is one of the few that has directly linked the regulation of AMPA receptor trafficking to memory processes in identified neuronal networks, by showing that fear-memory induced reduction in AMPA/NMDA ratio at thalamic-ITC synapses is associated with a reduced postsynaptic AMPA receptor density