Effects of dietary protein and fat level and rapeseed oil on growth and tissue fatty acid composition and metabolism in Atlantic salmon (Salmo salar L.) reared at low water temperatures

A 12 week feeding trial was conducted to elucidate the interactive effects of dietary fat and protein contents and oil source on growth, fatty acid composition, protein retention efficiency (PRE) and β-oxidation activity of muscle and liver in Atlantic salmon (Salmo salar L.) at low water temperatures (4.2 oC). Triplicate groups of Atlantic salmon (initial weight 1168 g) were fed six isoenergetic diets formulated to provide either 390 g kg-1 protein and 320 g kg-1 fat (high protein (HP) diets) or 340 g kg-1 protein and 360 g kg-1 fat (low protein (LP) diets); within each dietary protein/fat level crude RO comprised 0, 30 or 60% (R0, R30, R60, respectively) of the added oil. After 12 weeks the overall growth and FCR were very good for all treatments (TGC; 4.76 (±0.23), FCR; 0.85 (±0.02)). Significant effects were shown due to oil source on SGR and TGC only. The liver and muscle FA compositions were highly affected by the graded inclusion of RO. The PRE was significantly affected by the dietary protein level, while no significant effects were shown in total β-oxidation capacity of liver and muscle. The results of this study suggest that more sustainable, lower protein diets with moderate RO inclusion can be used in Atlantic salmon culture at low water temperatures with no negative effects on growth and feed conversion, no major detrimental effects on lipid and fatty acid metabolism and a positive effect on protein sparing

Particle Acceleration at Relativistic Shocks

I review the current status of Fermi acceleration theory at relativistic shocks. I first discuss the relativistic shock jump conditions, then describe the non-relativistic Fermi mechanism and the differences introduced by relativistic flows. I present numerical calculations of the accelerated particle spectrum, and examine the maximum energy attainable by this process. I briefly consider the minimum energy for Fermi acceleration, and a possible electron pre-acceleration mechanism.Comment: 17 pages, 4 figures. To appear in "Relativistic Flows in Astrophysics", A.W. Guthmann, M. Georganopoulos, A. Marcowith and K. Manolokou, eds., Lecture Notes in Pysics, Springer Verla

The effects of increasing dietary levels of soy protein concentrate (SPC) on the immune responses and disease resistance (furunculosis) of vaccinated and non-vaccinated Atlantic salmon (Salmo salar L.) parr

Juvenile salmon, with an initial weight of 9g, were fed three experimental diets, formulated to replace 35 (SPC35), 58 (SPC58) and 80 (SPC80) of high quality fishmeal (FM) with soy protein concentrate (SPC) in quadruplicate tanks. Higher dietary SPC inclusion was combined with increased supplementation of methionine, lysine, threonine and phosphorus. The experiment was carried out for 177 days. On day 92 salmon in each tank were bulk weighed. Post weighing eighty salmon from each tank were redistributed in two sets of 12 tanks. Salmon from the first set of tanks were vaccinated, while the second group was injected with phosphate buffer saline (PBS). Salmon were sampled on day 92 (pre-vaccination), day 94 (2 days post vaccination [dpv]/PBS injection [dpPBSinj]) and day 154 (62 dpv/dpPBSinj) of the trial for the assessment of their immune responses, prior to the performance of salmon bulk weights for each tank. On day 154, fish from each tank were again bulk weighed and then seventeen salmon per tank were redistributed in two sets of twelve tanks and intra-peritoneally infected with Aeromonas salmonicida. At Day 154, SPC80 demonstrated lower performance (weight gain, specific growth rate and thermal growth coefficient and feed conversion ratio) compared to SPC35 salmon. Reduced classical and total complement activities for salmon fed diets with over 58% of protein from SPC, were demonstrated prior to vaccination. Reduced alternative complement activity was detected for both SPC58 and SPC80 salmon at 2 dpv and for the SPC80 group at 62 dpv. Total and classical complement activities demonstrated no differences among the dietary groups after vaccination. Numerical increases in classical complement activity were apparent upon increased dietary SPC levels. Increased phagocytic activity (% phagocytosis and phagocytic index) was exhibited for the SPC58 group compared to SPC35 salmon at 62 dpPBSinj. No differences in serum lysozyme activity, total IgM, specific antibodies, protein, glucose and HKM respiratory burst were detected among the dietary groups at any timepoint or state. Mortalities as a result of the experimental infection only occurred in PBS-injected fish. No differences in mortality levels were demonstrated among the dietary groups. SPC58 diet supported both good growth and health in juvenile Atlantic salmon while SPC80 diet did not compromise salmon’ immunity or resistance to intraperitoneally inflicted furunculosis

Probing Pulsar Winds Using Inverse Compton Scattering

We investigate the effects of inverse Compton scattering by electrons and positrons in the unshocked winds of rotationally-powered binary pulsars. This process can scatter low energy target photons to produce gamma rays with energies from MeV to TeV. The binary radio pulsars PSR B1259-63 and PSR J0045-73 are both in close eccentric orbits around bright main sequence stars which provide a huge density of low energy target photons. The inverse Compton scattering process transfers momentum from the pulsar wind to the scattered photons, and therefore provides a drag which tends to decelerate the pulsar wind. We present detailed calculations of the dynamics of a pulsar wind which is undergoing inverse Compton scattering, showing that the deceleration of the wind of PSR B1259-63 due to `inverse Compton drag' is small, but that this process may confine the wind of PSR J0045-73 before it attains pressure balance with the outflow of its companion star. We calculate the spectra and light curves of the resulting inverse Compton emission from PSR B1259-63 and show that if the size of the pulsar wind nebula is comparable to the binary separation, then the gamma-ray emission from the unshocked wind may be detectable by atmospheric Cerenkov detectors or by the new generation of satellite-borne gamma-ray detectors such as INTEGRAL and GLAST. This mechanism may therefore provide a direct probe of the freely-expanding regions of pulsar winds, previously thought to be invisible.Comment: To be published in Astroparticle Physics. 27 pages, 5 figure

Arachidonic acid, arachidonic/eicosapentaenoic acid ratio, stearidonic acid and eicosanoids are involved in dietary-induced albinism in Senegal sole (Solea senegalensis)

Senegal sole larvae were fed live prey enriched with different amounts of arachidonic acid (ARA, 20:4n-6) and eicosapentaenoic acid (EPA, 20:5n-3) to re-evaluate the effect of these two fatty acids on flatfish pigmentation. Echium oil, a plant derived oil rich in gamma-linolenic acid (GLA, 18:3n-6) and stearidonic acid (SDA, 18:4n-3) was also used as a component of one of the enrichment emulsions. Although ARA content did not have any effect on growth there was a clear influence on pigmentation that correlated clearly with prostaglandin production. Inclusion of Echium oil, on the contrary, exerted a positive effect on pigmentation rate even though dietary ARA levels were as high as in the other emulsions. The relationships between dietary ARA levels and dietary ARA/EPA ratio, prostaglandin production and pigmentation are discussed

Interactive effects of dietary protein/lipid level and oil source on growth, feed utilisation and nutrient and fatty acid digestibility of Atlantic salmon

Although the use of fish meal (FM) and fish oil (FO) has been extensive in Atlantic salmon culture, there is a growing need for less reliance on these commodities. Moreover, it is crucial for the aquafeed industry to optimise the use of dietary protein and to improve the protein utilisation in salmon diets. The interactive effects of the dietary protein/lipid level and rapeseed oil (RO) inclusion on growth, feed utilisation, nutrient and fatty acid (FA) digestibility and whole body chemical composition of large Atlantic salmon (Salmo salar L.), reared at summer water temperatures (11.6 °C), were investigated in a ten week feeding trial. The fish (initial weight 2053 g) were fed six isoenergetic diets in a factorial design containing 350 g kg−1/350 g, kg−1, 330 g kg−1/360 g kg−1, 290 g kg−1/380 g kg−1 of protein/lipid for high protein (HP), medium protein (MP) and low protein (LP) diets, respectively. At all protein/lipid levels the oil source was either FO or RO (60% of the added oil). At the end of the trial the final weights ranged from 3340–3664 g and the FCR from 0.99– 1.10. The protein level did not affect significantly any of the growth parameters but the oil source had a significant effect on final weight, specific growth rate (SGR) and thermal growth coefficient (TGC), showing improved growth with RO inclusion. This could be explained by the significantly higher lipid digestibility of the fish fed the diets containing RO (86.1 vs. 92.2%) which was probably affected by the diet FA composition; the apparent digestibility coefficient (ADC) of saturated FA, and to a lesser extent of unsaturated FA and especially monoenes, was improved by RO inclusion. The protein ADC was significantly affected by the protein level indicating a higher ADC for the HP diets compared to the LP (80.1 vs. 77.7%, respectively). Regarding the whole body composition, moisture was significantly affected by both factors, the fat content was significantly affected only by the oil source, while significant interactions were shown for the protein content. In conclusion, the results of this study suggest that low protein/high lipid diets can be used with no negative effects on the growth, FCR and chemical composition of Atlantic salmon reared at high water temperatures. Moreover, the replacement of FO with RO can enhance the growth of the fish as well as the nutrient and FA digestibility of the diets

Inverse Compton Emission of TeV Gamma Rays from PSR B1259-63

We derive light curves for the hard gamma-ray emission, at energies up to several TeV, expected from the unique pulsar/Be-star binary system PSR B1259-63. This is the only known system in our galaxy in which a radio pulsar is orbiting a main sequence star. We show that inverse Compton emission from the electrons and positrons in the shocked pulsar wind, scattering target photons from the Be star, produces a flux of hard gamma-rays that should be above the sensitivity threshold of present day atmospheric Cerenkov detectors. Furthermore, we predict that the flux of hard gamma-rays produced via this mechanism has a characteristic variation with orbital phase that should be observable, and which is not expected from any other mechanism.Comment: To be published in Astroparticle Physics. 24 pages, 8 figure

Two qubits of a W state violate Bell's inequality beyond Cirel'son's bound

It is shown that the correlations between two qubits selected from a trio prepared in a W state violate the Clauser-Horne-Shimony-Holt inequality more than the correlations between two qubits in any quantum state. Such a violation beyond Cirel'son's bound is smaller than the one achieved by two qubits selected from a trio in a Greenberger-Horne-Zeilinger state [A. Cabello, Phys. Rev. Lett. 88, 060403 (2002)]. However, it has the advantage that all local observers can know from their own measurements whether their qubits belongs or not to the selected pair.Comment: REVTeX4, 5 page