Naked Singularities in Higher Dimensional Szekeres Space-time

In this paper we study the quasi-spherical gravitational collapse of (n+2) dimensional Szekeres space-time. The nature of the central shell focusing singularity so formed is analyzed by studying both the radial null and time-like geodesic originated from it. We follow the approach of Barve et al to analyze the null geodesic and find naked singularity in different situations.Comment: 11 Latex Pages, 4 figures, RevTex styl

Effects of Standardized Ileal Digestible Valine:Lysine Ratio on the Growth Performance and Economics of Finishing Pigs from 55 to 100 lb

The objective of these experiments was to determine the effects of SID Val:Lys ratio in low CP and low lysine diets on the growth performance and economics of finishing pigs from 55 to 100 lb. In Exp. 1, a total of 1,134 gilts (PIC 337 × 1050, initially 68.8 lb BW) were used in a 19-d growth trial with 27 pigs per pen and seven pens per treatment in a randomized complete block design with pens blocked by initial average BW. There was a total of six dietary treatments: 59.0, 62.5, 65.9, 69.6, 73.0, and 75.5% SID Val:Lys ratio. In Exp. 2, a total of 2,100 gilts (PIC 327 × 1050, initially 56.6 lb BW) were used in a 22-d growth trial with 25 pigs per pen and 12 pens per treatment in a randomized complete block design with pens blocked by initial average BW. There was a total of seven dietary treatments: 57.0, 60.6, 63.9, 67.5, 71.1, 74.4, and 78.0% SID Val:Lys ratio. In both experiments, the intermediate Val:Lys levels were obtained by blending different proportions of the low and high Val:Lys diets. Responses measured at the pen level were analyzed using general linear and non-linear mixed models. Competing statistical models were: a broken-line linear ascending (BLL) model, a broken-line quadratic ascending (BLQ) model, and a quadratic polynomial (QP). Competing models were compared using Bayesian information criteria (BIC). In Exp. 1, ADG increased linearly (P = 0.009) with increasing SID Val:Lys ratio whereas ADFI only marginally increased (linear, P = 0.098) with no evidence for differences on F/G. Feed cost per pig, feed cost per lb of gain, and total revenue per pig increased (linear, P \u3c 0.009) with increasing SID Val:Lys ratio without evidence for differences in IOFC. In Exp. 2, ADG and ADFI increased (P \u3c 0.002) with increasing SID Val:Lys ratio resulting in an improvement in F/G (P \u3c 0.001). Similarly, increasing SID Val:Lys ratio increased feed cost per pig (quadratic, P \u3c 0.001), feed cost per lb of gain (linear, P \u3c 0.001), total revenue (quadratic, P \u3c 0.001), and IOFC (quadratic, P \u3c 0.001). In conclusion, the SID Val:Lys ratio to optimize performance ranged from 71.0% for minimum F/G to 74.4% for maximum ADG. However, feed cost per lb of gain was minimized at less than 57% SID Val:Lys ratio and maximum income over feed cost was estimated at 62.3% SID Val:Lys ratio with a plateau thereafter. Therefore, 99% of the optimum ADG and F/G were estimated at approximately 69% and 65% SID Val:Lys ratio, respectively

Gravitational Collapse and Cosmological Constant

We consider here the effects of a non-vanishing cosmological term on the final fate of a spherical inhomogeneous collapsing dust cloud. It is shown that depending on the nature of the initial data from which the collapse evolves, and for a positive value of the cosmological constant, we can have a globally regular evolution where a bounce develops within the cloud. We characterize precisely the initial data causing such a bounce in terms of the initial density and velocity profiles for the collapsing cloud. In the cases otherwise, the result of collapse is either formation of a black hole or a naked singularity resulting as the end state of collapse. We also show here that a positive cosmological term can cover a part of the singularity spectrum which is visible in the corresponding dust collapse models for the same initial data.Comment: 18 pages, no figure

On isotropic cylindrically symmetric stellar models

We attempt to match the most general cylindrically symmetric vacuum space-time with a Robertson-Walker interior. The matching conditions show that the interior must be dust filled and that the boundary must be comoving. Further, we show that the vacuum region must be polarized. Imposing the condition that there are no trapped cylinders on an initial time slice, we can apply a result of Thorne's and show that trapped cylinders never evolve. This results in a simplified line element which we prove to be incompatible with the dust interior. This result demonstrates the impossibility of the existence of an isotropic cylindrically symmetric star (or even a star which has a cylindrically symmetric portion). We investigate the problem from a different perspective by looking at the expansion scalars of invariant null geodesic congruences and, applying to the cylindrical case, the result that the product of the signs of the expansion scalars must be continuous across the boundary. The result may also be understood in relation to recent results about the impossibility of the static axially symmetric analogue of the Einstein-Straus model.Comment: 13 pages. To appear in Classical and Quantum Gravit

Effects of Amino Acid and Energy Intake During Late Gestation on Piglet Birth Weight and Reproductive Performance of Gilts and Sows Housed Under Commercial Conditions

The objective of this study was to determine the effects of amino acid (AA) and energy intake during late gestation on piglet birth weight and reproductive performance of high-performing gilts and sows housed under commercial conditions. At d 90 of gestation, a total of 1,102 females (PIC 1050) were housed in pens by parity group (P1 or P2+), blocked by weight within each pen, and each female was randomly assigned to dietary treatments within weight block. Dietary treatments consisted of combinations of 2 standardized ileal digestible (SID) AA (10.7 or 20.0 g SID Lys intake/d with other AA meeting or exceeding the NRC [2012] recommendations as a ratio to Lys) and 2 energy intakes (4.50 or 6.75 Mcal/d intake of NE) in a 2 × 2 factorial arrangement. Data were analyzed using generalized linear mixed models with parity group and dietary treatments as the linear predictor and random effects of pen as the experimental unit for parity and the individual female as the experimental unit for dietary treatments. With high energy intake, the magnitude of BW gain during late gestation was greater (AA × Energy, P \u3c 0.001) with increasing AA intake compared with increasing AA at low energy intake. Gilts gained more weight at low energy intake than sows (parity × energy, P \u3c 0.001); however, there was no evidence for differences (P = 0.601) in weight gain between gilts and sows at high energy intake. Sows fed high-energy intake had marginally reduced probability of piglets born alive (parity × energy, P = 0.092) compared with sows fed low energy, but no evidence for differences in gilts was observed. This was due to the increased probability (parity × energy, P = 0.014) of stillborns to be higher in sows fed high energy intake. There was no evidence for differences between the dietary treatments for litter birth weight and individual piglet birth weight of total piglets born. However, individual born-live birth weight was heavier (P =0.011) for females fed high-energy intake treatments compared to those with low energy intake. Born-alive piglets from sows were heavier (P \u3c 0.001) than those from gilts. There was a lower probability (P = 0.034) of pre-weaning mortality for females fed high AA intake compared to low AA intake, regardless of energy level. There was no evidence for differences between the dietary treatments on farrowing rate, number of total piglets born, and percent of piglets born alive in the subsequent cycle. In conclusion, 1) body weight gain of gilts and sows depends not only on energy but also AA intake, 2) sows fed an increased amount of energy had increased stillborn rates, 3) the positive effect of increased amount of feed during late gestation on individual piglet birth weight, 30 g per pig, was due to energy rather than AA intake

Modeling the Effects of Standardized Ileal Digestible Tryptophan:Lysine Ratio on Growth Performance of 65- to 275-lb Pigs

The objective of this study was to model the effects of standardized ileal digestible (SID) Trp:Lys ratio on growth performance of 65- to 275-lb pigs. The present experiment, along with three previous experiments from Gonçalves et al. (2014), were used in the analysis. For all studies, dietary treatments consisted of SID Trp:Lys ratios of 14.5, 16.5, 18.0, 19.5, 21.0, 22.5, and 24.5%. The experiments were 21 d in duration and used corn and soybean meal-based diets with 30% dried distillers grains with solubles formulated to be deficient in Lys at the end of each of the experiments. In the current experiment, a total of 975 gilts (337 × 1050; PIC, Hendersonville, TN) were used with initial BW of 234.1 ± 6.8 lb and final BW of 274.9 ± 10.4 (mean ± SD). Pens of pigs were blocked by weight and assigned to one of the seven dietary treatments in a randomized complete block design. There were 6 pens/treatment with 20 to 24 pigs per pen. For 235 to 275 lb-pigs, increasing SID Trp:Lys improved ADG (quadratic, P \u3c 0.022), ADFI (linear, P \u3c 0.001), and F/G (linear, P \u3c 0.001). Data from all experiments were then combined for analysis using linear and non-linear mixed models with random effects of experiment and weight block nested within experiment allowing for heterogeneous variances. Competing models included broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP). In the combined analysis for ADG, QP was the best fitting model and estimated SID Trp:Lys requirement at 23.5% (95% CI: [22.7, 24.3%]). In the combined analysis for F/G, BLL and BLQ had comparable fit and estimated SID Trp:Lys requirements at 16.9% (95% CI: [16.0, 17.8%]) and 17.0% (95% CI: [15.0, 18.9%]), respectively. Thus, the estimated mean requirements for SID Trp:Lys for 65- to 275-lb pigs ranged from 16.9% for optimum mean F/G to 23.5% for maximum mean ADG. Furthermore, 95% of the maximum estimated mean ADG was obtained by feeding 17.6% SID Trp:Lys and 98% of the maximum estimated mean ADG was obtained by feeding 19.8% SID Trp:Lys

Effects of standardized ileal digestible valine-to-lysine ratio on growth performance of twenty-five- to forty-five-kilogram pigs under commercial conditions

Citation: Goncalves, M. A. D., Tokach, M. D., Dritz, S. S., Bello, N. M., Touchette, K. J., Goodband, R. D., . . . Woodworth, J. C. (2016). Effects of standardized ileal digestible valine-to-lysine ratio on growth performance of twenty-five- to forty-five-kilogram pigs under commercial conditions. Journal of Animal Science, 94, 19-20. doi:10.2527/msasas2016-043Two experiments were conducted to estimate the standardized ileal digestible (SID) Val:Lys requirement for growth performance in 25- to 45-kg pigs. In Exp. 1, 1134 gilts (PIC 337), initially 31.2 kg (SD 2.0) BW, were used in a 19-d trial with 27 pigs/pen and 7 pens/treatment. In Exp. 2, 2100 gilts (PIC 327), initially 25.4 ± 1.9 kg BW, were used in a 22-d trial with 25 pigs/pen and 12 pens/treatment. In both experiments, treatments were blocked by initial BW in a randomized complete block design. In Exp. 1, there were 6 treatments with SID Val:Lys at 59.0, 62.5, 65.9, 69.6, 73.0, and 75.5%. For Exp. 2, there were 7 treatments with SID Val:Lys at 57.0, 60.6, 63.9, 67.5, 71.1, 74.4, and 78.0%. Diets were formulated to ensure that Lys was the second limiting AA throughout the experiments. Responses were analyzed separately for each experiment using general linear and nonlinear heteroskedastic mixed models, including initial BW as an explanatory covariate and BW block as a random effect. In Exp. 1, ADG linearly increased with increasing SID Val:Lys (P = 0.009; 680, 717, 717, 712, 744, and 726 ± 17.1 g, respectively), whereas no significant treatment differences were observed for G:F (0.467, 0.467, 0.472, 0.474, 0.481, and 0.472 ± 0.0084, respectively). In Exp. 2, ADG (quadratic, P = 0.002; 621, 662, 717, 708, 708, 726, and 717 ± 16.1 g, respectively) and G:F increased (linear, P  78.0) SID Val:Lys. The best-fitting model for G:F was also a QP (prediction equation: ?0.04 + 1.36 × SID Val:Lys ? 0.94 × SID Val:Lys2) with optimum G:F estimated at 72.3% (95% CI 64.0 to > 78.0) SID Val:Lys. In conclusion, 67% SID Val:Lys was able to capture 99% of maximum ADG and G:F in 25- to 45-kg pigs

Effects of amino acids and energy intake during late gestation of high-performing gilts and sows on litter and reproductive performance under commercial conditions

Citation: Goncalves, M. A. D., Gourley, K. M., Dritz, S. S., Tokach, M. D., Bello, N. M., DeRouchey, J. M., . . . Goodband, R. D. (2016). Effects of amino acids and energy intake during late gestation of high-performing gilts and sows on litter and reproductive performance under commercial conditions. Journal of Animal Science, 94(5), 1993-2003. doi:10.2527/jas.2015-0087The objective of this study was to determine the effects of AA and energy intake during late gestation on piglet birth weight and reproductive performance of high-performing (14.5 total born) gilts and sows housed under commercial conditions. At d 90 of gestation, a total of 1,102 females (PIC 1050) were housed in pens by parity group (gilts or sows) with approximately 63 gilts and 80 sows in each pen, blocked by BW within each pen, and each female was randomly assigned to dietary treatments within BW block. Dietary treatments consisted of combinations of 2 standardized ileal digestible (SID) AA intakes (10.7 or 20.0 g/d SID Lys and other AA met or exceeded the NRC [2012] recommendations) and 2 energy intakes (4.50 or 6.75 Mcal/d intake of NE) in a 2 x 2 factorial arrangement. Data were analyzed using generalized linear mixed models specified to recognize pen as the experimental unit for parity and the individual female as the experimental unit for dietary treatments. Results indicate an overall positive effect of high energy intake on BW gain during late gestation, although this effect was more manifest under conditions of high, as opposed to low, AA intake (interaction, P < 0.001). Furthermore, the magnitude of BW gain response to increased energy intake was greater (P < 0.001) for sows compared with gilts. Sows fed high energy intake had a reduced probability of piglets born alive (P < 0.004) compared with those fed low energy, but no evidence for differences was found in gilts. This can be explained by an increased probability (P = 0.002) of stillborns in sows fed high energy intake vs. sows fed low energy intake. There were no evidences for differences among dietary treatments in litter birth weight and individual piglet birth weight of total piglets born. However, individual born alive birth weight was approximately 30 +/- 8.2 g heavier (P = 0.011) for females fed high, as opposed to low, energy intake. Furthermore, piglets born alive were approximately 97 +/- 9.5 g heavier (P < 0.001) for sows than for gilts. Preweaning mortality was decreased (P = 0.034) for females fed high AA intake compared with females fed low AA intake regardless of energy level. In conclusion, 1) BW gain of gilts and sows depended not only on energy but also on AA intake, 2) sows fed increased amount of energy had an increased stillborn rate, and 3) increased energy intake during late gestation had a positive effect on individual piglet birth weight with no evidence for such an effect for AA intake

The Possibility of Thermal Instability in Early-Type Stars Due to Alfven Waves

It was shown by dos Santos et al. the importance of Alfv\'en waves to explain the winds of Wolf-Rayet stars. We investigate here the possible importance of Alfv\'en waves in the creation of inhomogeneities in the winds of early-type stars. The observed infrared emission (at the base of the wind) of early-type stars is often larger than expected. The clumping explains this characteristic in the wind, increasing the mean density and hence the emission measure, making possible to understand the observed infrared, as well as the observed enhancement in the blue wing of the $H_\alpha$ line. In this study, we investigate the formation of these clumps a via thermal instability. The heat-loss function used, $H(T,n)$, includes physical processes such as: emission of (continuous and line) recombination radiation; resonance line emission excited by electron collisions; thermal bremsstrahlung; Compton heating and cooling; and damping of Alfv\'en waves. As a result of this heat-loss function we show the existence of two stable equilibrium regions. The stable equilibrium region at high temperature is the diffuse medium and at low temperature the clumps. Using this reasonable heat-loss function, we show that the two stable equilibrium regions can coexist over a narrow range of pressures describing the diffuse medium and the clumps.Comment: 21 pages (psfig.sty), 5 figures (included), ApJ accepted. Also available at http://www.iagusp.usp.br/preprints/preprint.htm