A proposal of a Renormalization Group transformation

We propose a family of renormalization group transformations characterized by free parameters that may be tuned in order to reduce the truncation effects. As a check we test them in the three dimensional XY model. The Schwinger--Dyson equations are used to study the renormalization group flow.Comment: Contribution to Lattice'94. uuencoded postscript fil

Electronic structure and transport properties of atomic NiO spinvalves

Ab-initio quantum transport calculations show that short NiO chains suspended in Ni nanocontacts present a very strong spin-polarization of the conductance. The generalized gradient approximation we use here predicts a similiar polarization of the conductance as the one previously computed with non-local exchange, confirming the robustness of the result. Their use as nanoscopic spinvalves is proposed.Comment: 2 pages, 1 figure; accepted in JMMM (Proceedings of ICM'06, Kyoto

Development and evaluation of a mechanistic model of post-absorptive nitrogen partitioning in lactating goats

[EN] Context. Goats contribute to global warming through emission of nitrous oxide from urine and faeces. To reduce nitrogen (N) excretion, improvements of N efficiency of goats is necessary. Aims. The aim of the present study was to develop and evaluate a dynamic mechanistic research-oriented model that explicitly represents N partition into faeces, urine and milk in dairy goats fed total mixed rations. Methods. Data from five N-balance dairy-goat experiments were used to develop a mechanistic dynamic model of post-absorptive N partition. Various representations considering either mass action or Michaelis-Menten kinetics of N usage for milk were proposed. Key results. The data for faecal and urine N responses were best fit by a straight line; whereas, data for milk N responses were best fit by curvilinear saturating curve. The model with curvilinear saturating curve had more precise parameter estimates, with the predicted N excretion in faeces (15.6 g/day), urine (15.4 g/day) and milk N output (11.7 g/day) being very close to the observed values, namely, 15.31 g N/day in faeces, 18.78 g N/day in urine and 12.24 g N/day in milk. Independent datasets with 12 studies were used to evaluate the model. The model tended to under-predict faecal N outflow at a lower N intake level and urinary N outflow at a higher N intake level, with the lowest mean bias for milk N outflow. Conclusions. The final chosen model was adequate to represent faecal, urinary and milk N outflows in dairy goats. Implications. The model has provided a mechanistic description of N usage, which is useful to frame and test hypotheses of physiological regulation of N use by goats, and focus on a more efficient transfer of dietary N into milk, reducing the N excretion in faeces and urine.This work is supported by a Climate Change Mitigation Project LIFE16/CCM/ES/000088. The authors thank Dr Ranga Appuhamy, Professor Ermias Kebreab and Professor Mark Hanigan for the many helpful recommendations in model definition, building and computer simulation-language implementation.Fernández Martínez, CJ.; Castro, J. (2020). Development and evaluation of a mechanistic model of post-absorptive nitrogen partitioning in lactating goats. Animal Production Science. 60(4):510-523. https://doi.org/10.1071/AN19132510523604Aguilera, J. F., Prieto, C., & FonollÁ, J. (1990). Protein and energy metabolism of lactating Granadina goats. British Journal of Nutrition, 63(2), 165-175. doi:10.1079/bjn19900104Bava, L., Rapetti, L., Crovetto, G. M., Tamburini, A., Sandrucci, A., Galassi, G., & Succi, G. (2001). Effects of a Nonforage Diet on Milk Production, Energy, and Nitrogen Metabolism in Dairy Goats throughout Lactation. Journal of Dairy Science, 84(11), 2450-2459. doi:10.3168/jds.s0022-0302(01)74695-4Brown, D. L., & Taylor, S. J. (1986). Deuterium Oxide Dilution Kinetics to Predict Body Composition in Dairy Goats. Journal of Dairy Science, 69(4), 1151-1155. doi:10.3168/jds.s0022-0302(86)80515-xBrun-Bellut, J., Kelly, J. M., Mathison, G. W., & Christopherson, R. J. (1991). Effect of rumen degradable protein and lactation on nitrogen metabolism in dairy goats. Canadian Journal of Animal Science, 71(4), 1111-1124. doi:10.4141/cjas91-133Criscioni, P., & Fernández, C. (2016). Effect of rice bran as a replacement for oat grain in energy and nitrogen balance, methane emissions, and milk performance of Murciano-Granadina goats. Journal of Dairy Science, 99(1), 280-290. doi:10.3168/jds.2015-9472Criscioni, P., Marti, J. V., Pérez-Baena, I., Palomares, J. L., Larsen, T., & Fernández, C. (2016). Replacement of alfalfa hay ( Medicago sativa ) with maralfalfa hay ( Pennisetum sp.) in diets of lactating dairy goats. Animal Feed Science and Technology, 219, 1-12. doi:10.1016/j.anifeedsci.2016.05.020Dennis, J. E., Gay, D. M., & Walsh, R. E. (1981). An Adaptive Nonlinear Least-Squares Algorithm. ACM Transactions on Mathematical Software, 7(3), 348-368. doi:10.1145/355958.355965Dijkstra, J., Oenema, O., van Groenigen, J. W., Spek, J. W., van Vuuren, A. M., & Bannink, A. (2013). Diet effects on urine composition of cattle and N2O emissions. Animal, 7, 292-302. doi:10.1017/s1751731113000578Doepel, L., Pacheco, D., Kennelly, J. J., Hanigan, M. D., López, I. F., & Lapierre, H. (2004). Milk Protein Synthesis as a Function of Amino Acid Supply. Journal of Dairy Science, 87(5), 1279-1297. doi:10.3168/jds.s0022-0302(04)73278-6Francoise Domngue, B. M., Dellow, D. W., Wilson, P. R., & Barry, T. N. (1991). Nitrogen metabolism, rumen fermentation, and water absorption in red deer, goats, and sheep. New Zealand Journal of Agricultural Research, 34(4), 391-400. doi:10.1080/00288233.1991.10417682DE JESUS DOS SANTOS, E., ALBUQUERQUE PEREIRA, M. L., PEREIRA DE FIGUEIREDO, M., DE OLIVEIRA SILVA, H. G., FERREIRA DA CRUZ, J., OLIVEIRA BARRETO, F., & BORGES SOUSA, L. (2016). Crude protein levels in diets of lactating goats: nitrogen balance, urea excretion and microbial protein synthesis. The Journal of Agricultural Science, 154(6), 1102-1109. doi:10.1017/s0021859616000277Fernández, C., Martí, J. V., Pérez-Baena, I., Palomares, J. L., Ibáñez, C., & Segarra, J. V. (2018). Effect of lemon leaves on energy and C–N balances, methane emission, and milk performance in Murciano-Granadina dairy goats. Journal of Animal Science, 96(4), 1508-1518. doi:10.1093/jas/sky028Fernández, C., Pérez-Baena, I., Marti, J. V., Palomares, J. L., Jorro-Ripoll, J., & Segarra, J. V. (2019). Use of orange leaves as a replacement for alfalfa in energy and nitrogen partitioning, methane emissions and milk performance of murciano-granadina goats. Animal Feed Science and Technology, 247, 103-111. doi:10.1016/j.anifeedsci.2018.11.008Harmeyer, J., & Martens, H. (1980). Aspects of Urea Metabolism in Ruminants with Reference to the Goat. Journal of Dairy Science, 63(10), 1707-1728. doi:10.3168/jds.s0022-0302(80)83132-8Kebreab, E., France, J., Mills, J. A. N., Allison, R., & Dijkstra, J. (2002). A dynamic model of N metabolism in the lactating dairy cow and an assessment of impact of N excretion on the environment1. Journal of Animal Science, 80(1), 248-259. doi:10.2527/2002.801248xLópez, M. C., Estellés, F., Moya, V. J., & Fernández, C. (2014). Use of dry citrus pulp or soybean hulls as a replacement for corn grain in energy and nitrogen partitioning, methane emissions, and milk performance in lactating Murciano-Granadina goats. Journal of Dairy Science, 97(12), 7821-7832. doi:10.3168/jds.2014-8424Malecky, M., Broudiscou, L. P., & Schmidely, P. (2009). Effects of two levels of monoterpene blend on rumen fermentation, terpene and nutrient flows in the duodenum and milk production in dairy goats. Animal Feed Science and Technology, 154(1-2), 24-35. doi:10.1016/j.anifeedsci.2009.07.004Molina-Alcaide, E., Morales-García, E. Y., Martín-García, A. I., Ben Salem, H., Nefzaoui, A., & Sanz-Sampelayo, M. R. (2010). Effects of partial replacement of concentrate with feed blocks on nutrient utilization, microbial N flow, and milk yield and composition in goats. Journal of Dairy Science, 93(5), 2076-2087. doi:10.3168/jds.2009-2628Rapetti, L., Bava, L., Tamburini, A., & Crovetto, G. M. (2005). Feeding behaviour, digestibility, energy balance and productive performance of lactating goats fed forage-based and forage-free diets. Italian Journal of Animal Science, 4(1), 71-83. doi:10.4081/ijas.2005.71Reynolds, C. K., & Kristensen, N. B. (2008). Nitrogen recycling through the gut and the nitrogen economy of ruminants: An asynchronous symbiosis1. Journal of Animal Science, 86(suppl_14), E293-E305. doi:10.2527/jas.2007-0475Romero-Huelva, M., Ramos-Morales, E., & Molina-Alcaide, E. (2012). Nutrient utilization, ruminal fermentation, microbial abundances, and milk yield and composition in dairy goats fed diets including tomato and cucumber waste fruits. Journal of Dairy Science, 95(10), 6015-6026. doi:10.3168/jds.2012-5573Sahlu, T., Goetsch, A. ., Luo, J., Nsahlai, I. ., Moore, J. ., Galyean, M. ., … Johnson, Z. . (2004). Nutrient requirements of goats: developed equations, other considerations and future research to improve them. Small Ruminant Research, 53(3), 191-219. doi:10.1016/j.smallrumres.2004.04.001Saltelli, A., Tarantola, S., & Chan, K. P.-S. (1999). A Quantitative Model-Independent Method for Global Sensitivity Analysis of Model Output. Technometrics, 41(1), 39-56. doi:10.1080/00401706.1999.10485594Santos, A. B., Pereira, M. L. A., Silva, H. G. O., Pedreira, M. S., Carvalho, G. G. P., Ribeiro, L. S. O., … Moreira, J. V. (2014). Nitrogen Metabolism in Lactating Goats Fed with Diets Containing Different Protein Sources. Asian-Australasian Journal of Animal Sciences, 27(5), 658-666. doi:10.5713/ajas.2013.13493Sari, M., Naserian, A. A., & Valizadeh, R. (2009). Effects of abomasal pectin infusion on milk production, digestion and nitrogen utilization pattern of lactating Saanen dairy goats. 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A nutrition mathematical model to account for dietary supply and requirements of energy and other nutrients for domesticated small ruminants: The development and evaluation of the Small Ruminant Nutrition System. Small Ruminant Research, 89(2-3), 174-184. doi:10.1016/j.smallrumres.2009.12.04

Finite-size scaling study of the d=4 site-diluted Ising

We study the four dimensional site-diluted Ising model using finite-size scaling techniques. We explore the whole parameter space (density-coupling) in order to determine the Universality Class of the transition line. Our data are compatible with Mean Field behavior plus logarithmic corrections.Comment: Contribution to LATTICE 9

Drought and Forest Decline in the Iberian Peninsula: A Simple Explanation for a Complex Phenomenom?

Different episodes of forest decline have been reported in several areas of the Northern Hemisphere during the 20th century. The explanation of this process included anthropogenic (air pollution), biotic (pathogens) and climatic factors. Among the climatic factors, the effects of acute or chronic droughts have been the most common explanation for the massive dieback observed. In the Iberian Peninsula, besides the pathogenic explanation which gives a paramount relevance to the fungus Phytophtora cinnamomi in many situations, the role of an increment in aridity (chronic) or the consequences of severe droughts (acute) have been empirically supported. The evident synchronism between forest decline and abnormally adverse climatic conditions, in addition to the reversibility of the process when precipitation intensity increased, are two major arguments for supporting the climatic involvement in the phenomenon. Nevertheless, the two most affected species in the episodes of oak decline in the Iberian Peninsula were Quercus ilex and Q. suber, which are representatives of the so called Mediterranean woody flora and which have been considered as more drought resistant than the temperate oak species that co-occur in this territory. The climatic complexity ofthe Iberian Peninsula, the many mechanisms for coping with water stress that have been described within the sclerophyllous Mediterranean flora and the effects of human management partially explain this paradox. Other forest species have also been affected by massive decline. Pinus sylvestris and Abies alba, which have their southern distribution limit in the mountain ranges of the Iberian Peninsula, are two examples of this situation. Both cases, besides the inmediate effects of some climatic perturbations, need the incorporation of different predisposing factors – mainly historical aspects to obtain a complete image of the process

A new approach for static NOx measurement in PTI

NOx emissions in vehicles are currently only controlled through the homologation process. There is a lack of knowledge to assess and control real NOx emissions of vehicles reliably. Even if vehicles in EU-27 are subject to Periodical Technical Inspection (PTI), NOx are not among the pollutants currently being controlled. For PTIs, tests need to be simple, quick, inexpensive, representative, and accurate. Ideally, tests need to be carried out under static conditions, without the need for a power bench or complex equipment. In this paper, a new approach for measuring NOx in PTI is proposed. The method has been developed and validated at a PTI Spanish station to ensure feasibility and repeatability. This method is based on the relationship between the “% engine load” value and exhaust NOx concentration at idle engine speed. Starting from the state of minimum possible power demand in a vehicle (idling and without any consumption), a load state with an average 98% increase in engine power demand is generated by connecting elements of the vehicle’s equipment. The relationship between power demand (through the “% engine load” value) and NOx concentration is then analyzed. The quality and representativity of this relationship have been checked with a p-value lower than 0.01. The method has been compared with a different NOx measurement technique, based on the simulation on a test bench and the ASM 2050 cycle, showing better performance in terms of repeatability and representativeness. The “% engine load” dispersion with the new approach is 7%, which ensures the reliability and repeatability of the method. The results show that the proposed method could be a valuable tool in PTI to detect high NOx emitting vehicles and to obtain information from the diesel vehicles fleet. © 2021 by the authors. Licensee MDPI, Basel, Switzerland