Extinction of a conditioned response in rainbow trout selected for high or low responsiveness to stress

Two lines of rainbow trout (Oncorhynchus mykiss) that exhibit divergent endocrine responsiveness to stressors also display disparate behavioral traits. To investigate whether the high-responding (HR) and low-responding (LR) fish also differ in cognitive function the rate of extinction of a conditioned response was compared between the two lines. Groups of HR and LR fish were exposed to a paired conditioned stimulus (CS; water-off) and unconditioned stimulus (US; confinement stressor). After exposure to 18 CS-US pairings at least 70% of individuals of both lines acquired a conditioned response (CR), manifested as an elevation of blood cortisol levels on presentation of the CS only. Post-conditioning, the fish were tested by presentation of the CS at weekly intervals, for 4 weeks, with no further reinforcement and the extinction of the CR in the two lines was compared. The decline in mean plasma cortisol levels after exposure to the CS over successive tests suggested that the CR was retained for a shorter period among the HR (<14 days) than LR fish (<21 days). The frequency of individuals within each line whose plasma cortisol levels indicated a stress response when exposed to the CS was significantly greater among the LR than HR fish at 14 and 21 days with no HR fish falling into this category at 21 days. At 28 days post-conditioning, there were no HR fish and only three LR fish that were categorized as “stressed”. These results suggest that there are differences in cognitive function between the two lines. Possible mechanisms underlying these differences are discussed

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

Sex-specific compensatory growth in food-deprived Nile tilapia

Female Nile tilapia incubate fertilized eggs in their mouth until they are released as alevins. Consequently, the female may not eat during this period. Thus, it would be expected that female Nile tilapia are more adapted to recovering from fasting than males, which do not display this behavior. To test this hypothesis we conducted an experiment with two groups of fish consisting of 7 males and 7 females each, with one fish per aquarium. The experiment was divided into three phases involving adjustment of the animals to experimental aquaria (0-15th day), fasting (16th-27th day), and refeeding (27th-42nd day). Compensatory growth performance was assessed by specific growth rate, weight, food conversion efficiency and food intake. Food conversion efficiency increased after fasting with a similar rate for both sexes. However, specific growth rate, food intake and weight gain (%) were significantly higher in males than in females in the refeeding phase. Thus, we conclude that male Nile tilapia can compensate for a fasting period more efficiently than females, refuting our hypothesis. A possible mechanism involved in the greater male compensation is that they presented greater hyperphagia than females, concomitantly with a similar rate of food conversion efficiency for both sexes during refeeding, which would probably be provoking greater growth in males

Determination of Chromium in Beef Heifers Nellore Supplemented with Chelate Chrome

<p><em>The objective of this work was to determine the amount of total chromium in beef heifers supplemented with chelated chromium in the rearing and finishing</em><em>. We used 80 Nelore heifers at 12 months of age with mineral supplementation associated or not to chelate chromium, with average live weight of 220 kg. Were selected 36 heifer seach experimental group for analysis of meat samples. For the determination of chromium residue in the muscle tissue of the sample was1.5 g digested in a mixture of 5 ml 65% nitric acid and 1 ml of 30% hydrogen peroxide at 120° C for 12 hours block microdigestor. The total content of chromium was determined by spectrophotometry of atomic absorption flame. The experimental design was completely randomized and the results were analyzed by analysis of variance (ANOVA) at 5% significance. It is concluded that the inclusion of chromium in the chelate heifers mineral supplementation increased the chromium content in the meat</em></p><object id="0a0a4a69-58ab-9db5-c9f8-7b96a8b9b693" width="0" height="0" type="application/gas-events-abn"></object

USE OF TWO DIGESTION METHODS IN THE EVALUATION OF CHROMIUM CONTENT IN CATTLE'S MEAT SUPPLEMENTED WITH CHROMIUM CHELATES

The present study aimed to analyze the chromium content in beef using two digestion methods. There were used samples from 24 18-month-old male cattle, and twelve of them were supplemented and twelve were not supplemented with chromium chelate. These samples were evaluated by atomic absorption spectroscopy, previously submitted to digestion method using nitric acid (65%) with hydrogen peroxide (35%) and to digestion method, using solution of nitric perchloric acid in the proportion 3:1. Immediately after the slaughter, the carcasses were sent to sanitary maturation. After 24 hours, samples between 12th and 13th rib in the muscle Longissimus Thoracis were taken. For evaluation, it was used completely randomized design (Die) and analysis of variance (ANOVA) at 5% of significance level. The results didn't evidenced any significant difference (p>0,05) between the (cromo) content, regardless the supplementation. The same happened with the digestion methods used

Pontos críticos de controle de Salmonella spp. no abate de frangos Critical control points for Salmonella spp. in poultry slaughter

Avaliou-se a presença de Salmonella spp. em esfregaços superficiais em 135 carcaças de frangos, coletadas em cinco diferentes fases do abate, utilizando os métodos de microbiologia convencional, reação em cadeia de polimerase (PCR) e imunoanálise. Os três métodos resultaram em tendência semelhante de detecção de Salmonella spp. nas carcaças de frango, ao longo da linha de abate. A maior frequência de Salmonella spp. foi determinada após o chuveiro de lavagem das carcaças, localizado entre a evisceração e o pré-resfriamento. Vinte (14,8%) esfregaços foram determinados pela metodologia convencional, 52 (38,5%) pela PCR e 66 (48,8%) pela imunoanálise. A menor contaminação foi encontrada na saída do pré-resfriamento, com frequências de 3,7%, 0% e 16,7%, respectivamente. Salmonella spp. foi encontrada em todas as fases de abate, mostrando a importância do monitoramento de diferentes pontos críticos de controle eventualmente identificados no abate de frangos.<br>The presence of Salmonella spp. in superficial swabs collected from 135 chicken carcasses in five different slaugther steps using the conventional microbiology, PCR, and immunoanalysis methods was evaluated. The three methods presented similar tendency to detect Salmonella spp. in the chicken carcasses along the slaugther line. The highest frequency of Salmonella spp. was found after the shower, located between the evisceration and the chiller. Twenty (14.8%) swabes were determined by the conventional methodology, 52 (38.9%) by the PCR, and 66 (48.9%) by the immunoanalysis. The lowest contamination was found after chiller tank, where the frequencies were 5 (3.7%), 0 (0%), and 24 (16.7%), respectively. Salmonella spp. was found in all the slaugther steps. This shows the importance for monitoring different CCP (Control Critical Point) in the poultry slaughterhouses

Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall

This paper reports the impact on confinement and power load of the high-shape 2.5MA ELMy H-mode scenario at JET of a change from an all carbon plasma facing components to an all metal wall. In preparation to this change, systematic studies of power load reduction and impact on confinement as a result of fuelling in combination with nitrogen seeding were carried out in JET-C and are compared to their counterpart in JET with a metallic wall. An unexpected and significant change is reported on the decrease of the pedestal confinement but is partially recovered with the injection of nitrogen.Comment: 30 pages, 16 figure