A comprehensive assessment of fish and other seafood in the Norwegian diet.

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Experimental and numerical study of the fragmentation of expanding warhead casings by using different numerical codes and solution techniques

AbstractThere has been increasing interest in numerical simulations of fragmentation of expanding warheads in 3D. Accordingly there is a pressure on developers of leading commercial codes, such as LS-DYNA, AUTODYN and IMPETUS Afea, to implement the reliable fracture models and the efficient solution techniques. The applicability of the Johnson–Cook strength and fracture model is evaluated by comparing the fracture behaviour of an expanding steel casing of a warhead with experiments. The numerical codes and different numerical solution techniques, such as Eulerian, Lagrangian, Smooth particle hydrodynamics (SPH), and the corpuscular models recently implemented in IMPETUS Afea are compared. For the same solution techniques and material models we find that the codes give similar results. The SPH technique and the corpuscular technique are superior to the Eulerian technique and the Lagrangian technique (with erosion) when it is applied to materials that have fluid like behaviour such as the explosive and the tracer. The Eulerian technique gives much larger calculation time and both the Lagrangian and Eulerian techniques seem to give less agreement with our measurements. To more correctly simulate the fracture behaviours of the expanding steel casing, we applied that ductility decreases with strain rate. The phenomena may be explained by the realization of adiabatic shear bands. An implemented node splitting algorithm in IMPETUS Afea seems very promising

Conformally dressed black hole in 2+1 dimensions

A three dimensional black hole solution of Einstein equations with negative cosmological constant coupled to a conformal scalar field is given. The solution is static, circularly symmetric, asymptotically anti-de Sitter and nonperturbative in the conformal field. The curvature tensor is singular at the origin while the scalar field is regular everywhere. The condition that the Euclidean geometry be regular at the horizon fixes the temperature to be $T=\frac{9\, r_+}{16\pi l^2}$. Using the Hamiltonian formulation including boundary terms of the Euclidean action, the entropy is found to be $\frac{2}{3}$ of the standard value ($\frac{1}{4} A$), and in agreement with the first law of thermodynamics.Comment: LaTeX ,RevTeX, 13pages, no figure

Influence of Dietary Oil Content and Conjugated Linoleic Acid (CLA) on Lipid Metabolism Enzyme Activities and Gene Expression in Tissues of Atlantic Salmon (Salmo salar L.)

The overall objective is to test the hypothesis that conjugated linoleic acid (CLA) has beneficial effects in Atlantic salmon through affecting lipid and fatty acid metabolism. The specific aims of the present study were to determine the effects of CLA on some key pathways of fatty acid metabolism including fatty acid oxidation and highly unsaturated fatty acid (HUFA) synthesis. Salmon smolts were fed diets containing two levels of fish oil (low, ~18% and high, ~34%) containing three levels of CLA (a 1:1 mixture of 9-cis,trans-11 and trans-10,cis-12 at 0, 1 and 2% of diet) for 3 months. The effects of dietary CLA on HUFA synthesis and β-oxidation were measured and the expression of key genes in the fatty acid oxidation and HUFA synthesis pathways, and potentially important transcription factors, peroxisome proliferators activated receptors (PPARs), determined in selected tissues. Liver HUFA synthesis and desaturase gene expression was increased by dietary CLA and decreased by high dietary oil content. Carnitine palmitoyltransferase-I (CPT-I) activity and gene expression were generally increased by CLA in muscle tissues although dietary oil content had relatively little effect. In general CPT-I activity or gene expression was not correlated with β-oxidation. Dietary CLA tended to increase PPARα and β gene expression in both liver and muscle tissues, and PPARγ in liver. In summary, gene expression and activity of the fatty acid pathways were altered in response to dietary CLA and/or oil content, with data suggesting that PPARs are also regulated in response to CLA. Correlations were observed between dietary CLA, liver HUFA synthesis and desaturase gene expression, and liver PPARα expression, and also between dietary CLA, CPT-I expression and activity, and PPARα expression in muscle tissues. In conclusion, this study suggests that dietary CLA has effects on fatty acid metabolism in Atlantic salmon and on PPAR transcription factors. However, further work is required to assess the potential of CLA as a dietary supplement, and the role of PPARs in the regulation of lipid metabolism in fish

Nutritional and environmental regulation of the synthesis of highly unsaturated fatty acids and of fatty-acid oxidation in Atlantic salmon (Salmo salar L.) enterocytes and hepatocytes

The aim was to determine if highly unsaturated fatty acid (HUFA) synthesis and fatty acid oxidation in Atlantic salmon (Salmo salar L.) intestine was under environmental and/or seasonal regulation. Triplicate groups of salmon were grown through a full two-year cycle on two diets containing either fish oil (FO), or a diet with 75% of the FO replaced by a vegetable oil (VO) blend containing rapeseed, palm and linseed oils. At key points in the life cycle, fatty acyl desaturation/elongation (HUFA synthesis) and oxidation activities were determined in enterocytes and hepatocytes using [1-14C]18:3n-3 as substrate. As observed previously, HUFA synthesis in hepatocytes showed peak activity at seawater transfer and declined thereafter, with activity consistently greater in fish fed the VO diet. In fish fed FO, HUFA synthesis in enterocytes in the freshwater stage was at a similar level to that in hepatocytes. However, HUFA synthesis in enterocytes increased rapidly after seawater transfer and remained high for some months after transfer before decreasing to levels that were again similar to those observed in hepatocytes. Generally, enterocyte HUFA synthesis was higher in fish fed the VO diet compared to the FO diet. Oxidation of [1-14C]18:3n-3 in hepatocytes from fish fed FO tended to decrease during the freshwater phase but then increased steeply, peaking just after transfer before decreasing during the remaining seawater phase. At the peak in oxidation activity around seawater transfer, activity was significantly lower in fish fed VO compared to fish fed FO. In enterocytes, oxidation of [1-14C]18:3 in fish fed FO showed a peak in activity just prior to seawater transfer. In fish fed VO, other than high activity at 9 months, the pattern was similar to that obtained in enterocytes from fish fed FO with a high activity around seawater transfer and declining activity in seawater. In conclusion, fatty acid metabolism in intestinal cells appeared to be under dual nutritional and environmental or seasonal regulation. The temporal patterns for fatty acid oxidation were generally similar in the two cell types, but HUFA synthesis in enterocytes peaked over the summer seawater phase rather than at transfer, as with hepatocytes, suggesting possibly different regulatory cues

Influence of dietary conjugated linoleic acid (CLA) and tetradecylthioacetic acid (TTA) on growth, lipid composition and key enzymes of fatty acid oxidation in liver and muscle of Atlantic cod (Gadus morhua L.)

The aim of the present study was to determine the effects of conjugated linoleic acid (CLA) and tetradecylthioacetic acid (TTA) on growth performance, and lipid and fatty acid metabolism in Atlantic cod. The overall objective being to test the hypotheses that CLA and TTA have beneficial effects in cod culture including decreased liver size and proportion through decreased lipid content, and increased nutritional quality through effects on fatty acid compositions including accumulation of bioactive fatty acids, CLA and TTA, in flesh. Juvenile cod were fed for three months on fish meal and fish oil diets of basically commercial formulation, but containing either 0.5% or 1% CLA, or 0.5% TTA. The effects of the functional fatty acids on growth, feed efficiency, body proximate composition, liver weight and lipid composition, fatty acid compositions of flesh and liver, and key enzymes of fatty acid oxidation were determined. Dietary CLA and TTA had no effect on growth parameters in cod juveniles, but viscero- and hepato-somatic indices were increased in fish fed 0.5% CLA and TTA, respectively. Proximate composition of whole fish was not affected by CLA or TTA, and there were no major effects of either functional fatty acid on lipid contents and compositions of liver and flesh. Dietary CLA and TTA were both incorporated into tissue lipids, with CLA deposited to a greater extent in liver, whereas TTA was deposited to a greater extent in flesh. In liver, acyl CoA oxidase (ACO) activity, but not carnitine palmitoyltransferase-I (CPT-I), was increased by CLA, whereas dietary TTA increased both ACO and CPT-I activities. In contrast, ACO activity was reduced by both CLA and TTA in red and white muscle, whereas CPT-I activity was generally not affected by CLA and TTA in either muscle tissue. Therefore, the results only partially supported the hypotheses tested, as CLA and TTA had few beneficial effects in Atlantic cod and did not enhance growth parameters, or improve feed conversion or potential yield through decreased adiposity or liver lipid deposition. However, nutritional quality could be enhanced, and cod fed CLA and/or TTA could be beneficial in the human diet, through provision of bioactive fatty acids with no detrimental effects on n-3 PUFA levels

Strain rate dependency and fragmentation pattern of expanding warheads

For the characterization of the behaviors of a metal material in events like expanding warheads, it is necessary to know its strength and ductility at high strain rates, around 104–105/s. The flyer plate impact testing produces the uniform stress and strain rates but the testing is expensive. The Taylor test is relatively inexpensive but produces non-uniform stress and strain fields, and the results are not so easily inferred for material modeling. In the split-Hopkinson bar (SHB), which may be used in compression, tension and torsion testing, the strain rates never exceeds 103/s. In the present work, we use the expanding ring test where the strain rate is 104–105/s. A streak camera is used to examine the expanding ring velocity, and a water tank is used to collect the fragments. The experimental results are compared with the numerical simulations using the hydrocodes AUTODYN, IMPETUS Afea and a regularized smooth particle (RSPH) software. The number of fragments increases with the increase in the expansion velocity of the rings. The number of fragments is similar to the experimental results. The RSPH software shows much the same results as the AUTODYN where the Lagrangian solver is used for the ring. The IMPETUS Afea solver shows a somewhat different fragmentation characteristic due to the node splitting algorithm that induces pronounced tensile splitting

Mitochondrion is the principal target for nutritional and pharmacological control of triglyceride metabolism

Fish oil polyunsaturated fatty acids and fibrate hypolipidemic drugs are potent hypotriglyceridemic agents that act by increasing fatty acid catabolism and decreasing triglyceride synthesis and secretion by the liver. A major unresolved issue is whether this hypotriglyceridemic effect can occur independent of induction of peroxisomal beta-oxidation, a predisposing factor for hepatocarcinogenesis. The present study was undertaken to determine which component of fish oil, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), is responsible for its triglyceride-lowering effect. We demonstrate that EPA and not DHA is the hypotriglyceridemic component of fish oil and that mitochondria and not peroxisomes are the principal target. Results obtained by fenofibrate feeding support the hypothesis that the mitochondrion is the primary site for the hypotriglyceridemic effect. In contrast to fibrates, EPA did not affect hepatic apolipoprotein C-III gene expression. Therefore, increased mitochondrial beta-oxidation with a concomitant decrease in triglyceride synthesis and secretion seems to be the primary mechanism underlying the hypotriglyceridemic effect of EPA and fibrates in rats, rabbits and possibly also in humans. In addition, these data show that lowering of plasma triglycerides can occur independently of any deleterious peroxisome proliferation