1,311 research outputs found

    Boundary Asymptotic Analysis for an Incompressible Viscous Flow: Navier Wall Laws

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    We consider a new way of establishing Navier wall laws. Considering a bounded domain Ω\Omega of R N , N=2,3, surrounded by a thin layer ÎŁÏ”\Sigma \epsilon, along a part Γ\Gamma2 of its boundary ∂Ω\partial \Omega, we consider a Navier-Stokes flow in ΩâˆȘ∂ΩâˆȘÎŁÏ”\Omega \cup \partial \Omega \cup \Sigma \epsilon with Reynolds' number of order 1/Ï”\epsilon in ÎŁÏ”\Sigma \epsilon. Using Γ\Gamma-convergence arguments, we describe the asymptotic behaviour of the solution of this problem and get a general Navier law involving a matrix of Borel measures having the same support contained in the interface Γ\Gamma2. We then consider two special cases where we characterize this matrix of measures. As a further application, we consider an optimal control problem within this context

    Contribution of mixing in the ABL to new particle formation based on observations

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    The connection between new particle formation and micro- and mesoscale meteorology was studied based on measurements at SMEAR II station in Southern Finland. We analyzed turbulent conditions described by sodar measurements and utilized these combined with surface layer measurements and a simple model to estimate the upper boundary layer conditions. Turbulence was significantly stronger on particle formation days and the organic vapor saturation ratio increase due to large eddies was stronger on event than nonevent days. We examined which variables could be the best indicators of new particle formation and concluded that the formation probability depended on the condensation sink and temporal temperature change at the top of the atmospheric boundary layer. Humidity and heat flux may also be good indicators for particle formation

    effects of low protein diets and rumen protected conjugated linoleic acid on production and carcass traits of growing double muscled piemontese bulls

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    The effects of low-protein (LP) diets and rumen-protected CLA on DMI, ADG, carcass traits, and health status of double-muscled Piemontese young bulls were investigated. Forty-eight bull calves (BW = 237 ± 24 kg) were divided in 4 groups and housed in 12 fully slatted pens. Bulls were fed 2 diets differing in CP density (high-protein (HP) diet: CP = 145 g/kg of DM; LP diet: CP = 108 g/kg of DM) and top-dressed with 80 g/d of rumen-protected CLA or 65 g/d of hydrogenated soybean oil. Orts were collected weekly and feed intake was estimated on a pen basis, with 3 replicated pens for each treatment. Each bull was weighed monthly and examined for alterations of the locomotion system by using the locomotion score as an index of lameness and by counting the number of swollen joints. Carcass quality traits were measured at slaughter, after a feeding period of 332 d. Compared with HP, LP reduced ADG only during the first 4 mo of the trial (1.30 vs. 1.53 kg/d, P = 0.003). However, be- cause of compensatory growth, over the whole trial, no significant effects attributable to CP or to additive were found on final BW (668 kg), ADG (1.19 kg/d), DMI (8.50 or 86 g/d per kg of BW 0.75 ), dressing percentage (67.3%), carcass conformation (5.2 points), and carcass fat covering (1.87 points). Feed efficiency was affected by a CP × additive interaction (P = 0.030), with CLA improving feed efficiency when added to the LP diets, whereas feed efficiency was reduced with the HP diets. The addition of both LP and CLA reduced the number of bulls presenting swollen joints (P = 0.001), and LP improved the locomotion score (P = 0.021) compared with HP. It was concluded that 10.8 g/kg of CP density in the diet is sufficient for double-muscled Piemontese bulls. The reduction in CP density from 145 to 108 g/ kg of DM, in addition to reducing the feeding cost, allows a strong reduction in N consumption without negative consequences on growth performance and car- cass traits

    Effects of fat supplementations on milk production and composition, ruminal and plasma parameters of dairy cows

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    The effects on milk yield and quality caused by the same amount (325 g/d/cow) of lipids provided by 3 different fat sources (hydrogenate palm fat, HF; calcium salt palm fat, CaSF; full-fat toasted soybean, TS), top dressed to a common total mixed ration, were investigated. Supplementations did not affect feed intake and milk yield, but markedly changed the acidic profile of milk fat. CaSF and TS significantly increased the proportions of unsaturated fatty acids of milk fat with respect to control and to HF. The 3 fat sources did not affect the concentrations of ammonia and VFA of rumen fluid. TS only slightly increased (P<0.10) plasma urea content because of a higher dietary protein supply, with respect to the other treatments. The use of a low amount of toasted and cracked full fat soybean seem to be interesting to increase the energy concentration of diets in replacement to commercial fat products and it can be use to modify the milk fat quality increasing the fraction with benefit effects on human health

    Characteristics of dairy farms in the North-Eastern part of Italy: rations, milk yield and nutrients excretion

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    This survey was aimed to evaluate the characteristics of dairy farms in the North- Eastern part of Po valley in terms of ration composition, milk yield and N and P excretions. Eightynine farms, with Italian Holstein Friesian cows, were selected in order to cover different situations in term of farm size and milk yield (MY). MY and quality were obtained from the national database of functional controls. Each farm was visited in order to collect information about ingredients and chemical composition of rations used. Farms were classified in four groups differing for dietary crude protein density (LCP15.3% DM) and for MY (LMY30 kg/d). N and P excretions were quantified by following a mass balance approach. Dietary crude protein content (CP) was not correlated to milk yield (MY) and quality. The estimated amounts of N excreted, discounted for 28% of N losses in atmosphere, were 78.5, 78.2, 87.2 and 89.1 kg/cow/year, and P excreted were 20.2, 18.6, 18.7 and 19.8 kg/cow/year for the LCPLMY, LCPHMY, HCPLMY, HCPHMY groups, respectively. On corn silage and cereals based rations, a dietary CP of 14.3% DM can support 31 kg MY/cow/day

    Obesity and the Risk for a Hematological Malignancy: Leukemia, Lymphoma, or Myeloma

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    Studies on obesity and the risk for hematological malignancies are reviewed. The paper includes a discussion of the metabolic effects of obesity and their possible role in linking increased body fat to neoplasia

    Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment

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    Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6–1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8 &amp;times; 10&lt;sup&gt;3&lt;/sup&gt; to 29 &amp;times;10&lt;sup&gt;3&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt; with a yearly median of 11.8 &amp;times; 10&lt;sup&gt;3&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt;. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79 &amp;plusmn; 6)%. Typical diurnal variation of the particle number concentration was related to the major emission patterns in cities, new particle formation, sinks of particles and meteorology. Shapes of the monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. New particle formation and growth unambiguously occurred on 83 days, which represent 27% of all relevant days. Hence, new particle formation and growth are not rare phenomena in Budapest. Their frequency showed an apparent seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. New particle formation events were linked to increased gas-phase H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; concentrations. In the studied area, new particle formation is mainly affected by condensation sink and solar radiation. The formation process seems to be not sensitive to SO&lt;sub&gt;2&lt;/sub&gt;, which was present in a yearly median concentration of 6.7 ÎŒg m&lt;sup&gt;−3&lt;/sup&gt;. This suggests that the precursor gas was always available in excess. Formation rate of particles with a diameter of 6 nm varied between 1.65 and 12.5 cm&lt;sup&gt;−3&lt;/sup&gt; s&lt;sup&gt;−1&lt;/sup&gt; with a mean and standard deviation of (4.2 &amp;plusmn; 2.5) cm&lt;sup&gt;−3&lt;/sup&gt; s&lt;sup&gt;−1&lt;/sup&gt;. Seasonal dependency for the formation rate could not be identified. Growth curves of nucleated particles were usually superimposed on the characteristic diurnal pattern of road traffic direct emissions. The growth rate of the nucleation mode with a median diameter of 6 nm varied from 2.0 to 13.3 nm h&lt;sup&gt;−1&lt;/sup&gt; with a mean and standard deviation of (7.7 &amp;plusmn; 2.4) nm h&lt;sup&gt;−1&lt;/sup&gt;. There was an indicative tendency for larger growth rates in summer and for smaller values in winter. New particle formation events increased the total number concentration by a mean factor and standard deviation of 2.3 &amp;plusmn; 1.1 relative to the concentration that occurred immediately before the event. Several indirect evidences suggest that the new particle formation events occurred at least over the whole city, and were of regional type. The results and conclusions presented are the first information of this kind for the region over one-year long time period

    Power calculation for gravitational radiation: oversimplification and the importance of time scale

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    A simplified formula for gravitational-radiation power is examined. It is shown to give completely erroneous answers in three situations, making it useless even for rough estimates. It is emphasized that short timescales, as well as fast speeds, make classical approximations to relativistic calculations untenable.Comment: Three pages, no figures, accepted for publication in Astronomische Nachrichte
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