9 research outputs found
Quasi-Black Holes from Extremal Charged Dust
One can construct families of static solutions that can be viewed as
interpolating between nonsingular spacetimes and those containing black holes.
Although everywhere nonsingular, these solutions come arbitrarily close to
having a horizon. To an observer in the exterior region, it becomes
increasingly difficulty to distinguish these from a true black hole as the
critical limiting solution is approached. In this paper we use the
Majumdar-Papapetrou formalism to construct such quasi-black hole solutions from
extremal charged dust. We study the gravitational properties of these
solutions, comparing them with the the quasi-black hole solutions based on
magnetic monopoles. As in the latter case, we find that solutions can be
constructed with or without hair.Comment: 18 page
Effect on Broiler Production Performance and Meat Quality of Feeding Ulva lactuca Supplemented with Carbohydrases
Macroalgae have been increasingly exploited worldwide for feed, food and biofuel
applications, due to their nutritive and bioactive compounds. Green seaweeds belonging to the genus
Ulva have high growth rates, which makes them suitable for being cultured in sustainable algae
production, such as an integrated multi-trophic aquaculture system. This is expected to increase the
use of Ulva sp. as an alternative source to conventional feedstuffs (e.g., cereals and soybean meal)
for poultry. The objective of the current study was to assess if the incorporation of 15% Ulva lactuca
in broiler chickens’ diet, combined or not with carbohydrate-active enzymes, would enhance meat
nutritional quality without compromising animal growth performance. Overall, U. lactuca led to
an accumulation of antioxidant carotenoids, n-3 PUFA and macrominerals, including magnesium,
potassium and phosphorus, in the breast muscle, with likely health benefits, without significantly
impairing growth performance. The supplementation of macroalgae with a recombinant ulvan lyase
reduced ileal viscosity with possible beneficial effects on broiler digestibility. Although dietary U.
lactuca showed potential to increase meat quality, it reduced meat overall acceptability, which suggests
the use of a lower algae inclusion level to prevent a negative meat sensory perception for consumersinfo:eu-repo/semantics/publishedVersio
Effect of Dietary Laminaria digitata with Carbohydrases on Broiler Production Performance and Meat Quality, Lipid Profile, and Mineral Composition
This article belongs to the Section Animal Nutrition.Simple Summary: Seaweeds represent promising alternatives to unsustainable conventional feed sources, such as cereals, incorporated in poultry diets. Brown macroalgae (e.g., Laminaria digitata) correspond to the largest cultured algal biomass worldwide and are rich in bioactive polysaccharides, minerals, and antioxidant pigments. However, their utilization as feed ingredients is limited due to the presence of an intricate gel-forming cell wall composed of indigestible carbohydrates, mainly alginate and fucose-containing sulfated polysaccharides. Therefore, supplementation with carbohydrate-active enzymes is required to disrupt the cell wall and allow seaweed nutrients to be digested and absorbed in poultry gut. The present study aimed to evaluate if the dietary inclusion of 15% L. digitata, supplemented or not with carbohydrases, could improve the nutritional value of poultry meat without impairing growth performance of broiler chickens. The results show that L. digitata increases antioxidant pigments and n-3 long-chain polyunsaturated fatty acids in meat, thus improving meat nutritional and health values. On the other hand, feeding algae at a high incorporation level impaired growth performance. Feed enzymatic supplementation had only residual effects, although alginate lyase decreased intestinal viscosity caused by dietary L. digitata with potential benefits for broiler digestibility.Abstract: We hypothesized that dietary inclusion of 15% Laminaria digitata, supplemented or not with carbohydrases, could improve the nutritional value of poultry meat without impairing animal growth performance. A total of 120 22-day old broilers were fed the following dietary treatments (n = 10) for 14 days: cereal-based diet (control); control diet with 15% L. digitata (LA); LA diet with 0.005% Rovabio® Excel AP (LAR); LA diet with 0.01% alginate lyase (LAE). Final body weight was lower and feed conversion ratio higher with LA diet than with the control. The ileal viscosity increased with LA and LAR diets relative to control but without differences between LAE and control. The pH of thigh meat was higher, and the redness value of breast was lower with LA diet than with control. Meat overall acceptability was positively scored for all treatments. The γ-tocopherol decreased, whereas total chlorophylls and carotenoids increased in meat with alga diets relative to control. The percentage of n-3 polyunsaturated fatty acids (PUFA) and accumulation of bromine and iodine in meat increased with alga diets compared with control. Feeding 15% of L. digitata to broilers impaired growth performance but enhanced meat quality by increasing antioxidant pigments, with beneficial effects on n-3 PUFA and iodine.The study was funded by the Fundação para a Ciência e a Tecnologia, Portugal, through the
PTDC/CAL-ZOO/30238/2017 grant, associated with a postdoctoral contract to M.M.C. and a PhD
fellowship to D.C. (SFRH/BD/126198/2016), as well as CIISA (UIDB/00276/2020), AL4AnimalS
(LA/P/0059/2020), and LEAF (UIDB/04129/2020) grants.info:eu-repo/semantics/publishedVersio
Enhancing meat quality of weaned piglets with the dietary incorporation of Ulva lactuca and carbohydrases supplementation
Pubmed Free articleThe impact of the dietary incorporation of 7% Ulva lactuca, a green seaweed, on the quality and nutritional value of piglet’s meat was assessed. U. lactuca is rich in nutrients and bioactive compounds but its cell wall is composed of complex polysaccharides that reduce their bioavailability. Therefore, the effect of supplementing piglet diets with exogenous carbohydrases was also assessed here. A total of 40 male weaned piglets were divided into four dietary groups, each with 10 piglets: control (wheat, maize and soybean meal-based diet), UL (7% U. lactuca replacing the control diet), UL +R (UL and 0.005% Rovabio®), and UL +E (UL and 0.01% ulvan lyase). The piglets were fed the diets for 2 weeks. The results showed that incorporating U. lactuca in piglet diets did not influence most of the meat quality traits (P >0.05). However, the incorporation of U. lactuca with the commercial carbohydrase (UL +R) increased the amount of the docosahexaenoic acid (DHA; 22:6n-3) in their meat (P =0.011) compared with the control, by 54%. In addition, meat from piglets fed seaweed diets showed a nearly two-fold increase in iodine contents (P <0.001). Meat tenderness, juiciness and overall acceptability of piglets fed the control diet and the UL diet were lower than those fed the diets containing seaweed and carbohydrases (P <0.001). Overall, the findings indicate that 7% U. lactuca in the diets of weaned piglets had no major detrimental effects on meat quality and their carbohydrase supplementation has the potential to improve meat sensory traits.Funding: This research was funded by Fundação para a Ciência e a Tecnologia (FCT), Portugal, through PTDC/CAL-ZOO/30238/2017 grant, associated with a post-doc contract to M.C., and PhD fellowships to J.M. P. (SFRH/BPD/116816/2016) and D.M.R. (SFRH/BD/143992/2019). CIISA (UIDB/00276/2020), AL4AnimalS (LA/P/0059/2020) and LEAF (UIDB/04129/2020) grants, also from FCT, are also acknowledged. The authors acknowledge Teresa Costa from Indukern, Lda. (Sintra, Portugal), for the Rovabio® Excel AP kind donation. The graphical abstract was created using BioRender.com (https://biorender.com/).info:eu-repo/semantics/publishedVersio
Influence of Feeding Weaned Piglets with Laminaria digitata on the Quality and Nutritional Value of Meat
Laminaria digitata is a novel feedstuff that can be used in pig diets to replace conventional
feedstuffs. However, its resilient cell wall can prevent the monogastric digestive system from accessing
intracellular nutrients. Carbohydrate-active enzyme (CAZyme) supplementation is a putative
solution for this problem, degrading the cell wall during digestion. The objective of this work was to
evaluate the effect of 10% L. digitata feed inclusion and CAZyme supplementation on the meat quality
and nutritional value of weaned piglets. Forty weaned piglets were randomly allocated to four experimental
groups (n = 10): control, LA (10% L. digitata, replacing the control diet), LAR (LA + CAZyme
(0.005% Rovabio® Excel AP)) and LAL (LA + CAZyme (0.01% alginate lyase)) and the trial lasted for
two weeks. The diets had no effect on any zootechnical parameters measured (p > 0.05) and meat
quality traits, except for the pH measured 24 h post-mortem, which was higher in LAL compared
to LA (p = 0.016). Piglets fed with seaweed had a significantly lower n-6/n-3 PUFA ratio compared
to control, to which the higher accumulation of C20:5n-3 (p = 0.001) and C18:4n-3 (p < 0.0001) contributed.
In addition, meat of seaweed-fed piglets was enriched with bromine (Br, p < 0.001) and iodine
(I, p < 0.001) and depicted a higher oxidative stability. This study demonstrates that the nutritional value
of piglets’ meat could be improved by the dietary incorporation of L. digitata, regardless of CAZyme
supplementation, without negatively affecting growth performance in the post-weaning stageinfo:eu-repo/semantics/publishedVersio
Electromagnetic radiation from collisions at almost the speed of light: an extremely relativistic charged particle falling into a Schwarzschild black hole
We investigate the electromagnetic radiation released during the high energy
collision of a charged point particle with a four-dimensional Schwarzschild
black hole. We show that the spectra is flat, and well described by a classical
calculation. We also compare the total electromagnetic and gravitational
energies emitted, and find that the former is supressed in relation to the
latter for very high energies. These results could apply to the astrophysical
world in the case charged stars and small charged black holes are out there
colliding into large black holes, and to a very high energy collision
experiment in a four-dimensional world. In this latter scenario the calculation
is to be used for the moments just after the black hole formation, when the
collision of charged debris with the newly formed black hole is certainly
expected. Since the calculation is four-dimensional, it does not directly apply
to Tev-scale gravity black holes, as these inhabit a world of six to eleven
dimensions, although our results should qualitatively hold when extrapolated
with some care to higher dimensions.Comment: 6 pages, 2 figure
Nariai, Bertotti-Robinson and anti-Nariai solutions in higher dimensions
We find all the higher dimensional solutions of the Einstein-Maxwell theory
that are the topological product of two manifolds of constant curvature. These
solutions include the higher dimensional Nariai, Bertotti-Robinson and
anti-Nariai solutions, and the anti-de Sitter Bertotti-Robinson solutions with
toroidal and hyperbolic topology (Plebanski-Hacyan solutions). We give explicit
results for any dimension D>3. These solutions are generated from the
appropriate extremal limits of the higher dimensional near-extreme black holes
in a de Sitter, and anti-de Sitter backgrounds. Thus, we also find the mass and
the charge parameters of the higher dimensional extreme black holes as a
function of the radius of the degenerate horizon.Comment: 10 pages, 11 figures, RevTeX4. References added. Published versio
Quasinormal modes of Schwarzschild black holes in four and higher dimensions
We make a thorough investigation of the asymptotic quasinormal modes of the
four and five-dimensional Schwarzschild black hole for scalar, electromagnetic
and gravitational perturbations. Our numerical results give full support to all
the analytical predictions by Motl and Neitzke, for the leading term. We also
compute the first order corrections analytically, by extending to higher
dimensions, previous work of Musiri and Siopsis, and find excellent agreement
with the numerical results. For generic spacetime dimension number D the
first-order corrections go as . This means that
there is a more rapid convergence to the asymptotic value for the five
dimensional case than for the four dimensional case, as we also show
numerically.Comment: 12 pages, 5 figures, RevTeX4. v2. Typos corrected, references adde
Produção de frutos e caracterização de ambientes de ocorrência de plantas nativas de araticum no cerrado de Goiás Fruit production and environment characterization of the occurrence of native plants of araticum in the Cerrado of Goiás state
Este estudo teve como objetivo avaliar a produção de frutos de araticum no Cerrado do Estado de Goiás. Foram selecionadas, para a realização do trabalho, 14 áreas de ocorrência natural do araticum no Estado de Goiás, de janeiro de 2000 a julho de 2002. Em cada área, foram selecionadas de 30 a 40 plantas adultas de araticum. O delineamento experimental adotado corresponde ao modelo hierárquico, para produção de frutos, sendo os dados obtidos submetidos à análise de variância. A estrutura espacial da variação fenotípica entre as populações das áreas analisadas foi investigada a partir do critério de ligação UPGMA. Os resultados demonstraram que a produção de frutos de araticum é baixa e variável entre as áreas e entre os anos, sendo a média de 2,97 aproveitáveis e de 1,37 frutos inaproveitáveis por planta. A variação fenotípica de caracteres morfológicos entre populações de araticum do Estado de Goiás não apresenta um padrão de estruturação espacial. A produção de frutos por planta é muito variável, sendo que algumas plantas apresentam características produtivas e de qualidade aparente de frutos que as credenciam com potencial para plantas-matrizes. As principais pragas que atacam os frutos de araticum são: Spermologus funereus, Cerconota anonella e Bephratelloides pomorum. A pressão antrópica sobre os ambientes naturais de produção de araticum tem reduzido a produção atual e pode inviabilizar as produções futuras.<br>This study had the objective to evaluate the production of araticum fruits in the Cerrado of the Goiás State. Fourteen areas with high natural occurrences of araticum in the whole state were selected from January 2000 to July 2002. In each area, thirty to forty mother trees were selected. The experimental research corresponds to the hierarchical model for the fruit production, and that means that the original data was submitted to an analysis of variance. The spatial phenotypic structure variation among populations was investigated through dendrograms by the UPGMA linking criterion. The results demonstrated that the production of araticum fruits is low and changeable in areas and years, and the average corresponds to 2.97 usable fruits and 1.37 not usable fruits per plant. The phenotypic variation of morphologic characters between populations of araticum of the Goiás state does not present a standard of space arrangement. The production of fruits per plant is very changeable, since some plants present productive and apparent quality characteristics of fruits that make them potential plants matrix. The main pests that attack the fruits of araticum are: Spermologus funereus, Cerconota anonella and Bephratelloides pomorum. The anthropic pressure on natural environments of production of araticum has reduced the current production and can make the future productions impracticable