Equation of state of hard oblate ellipsoids by replica exchange Monte Carlo

We implemented the replica exchange Monte Carlo technique to produce the equation of state of hard 1:5 aspect-ratio oblate ellipsoids for a wide density range. For this purpose, we considered the analytical approximation of the overlap distance given by Bern and Pechukas and the exact numerical solution given by Perram and Wertheim. For both cases we capture the expected isotropic-nematic transition at low densities and a nematic-crystal transition at larger densities. For the exact case, these transitions occur at the volume fraction 0.341, and in the interval $0.584-0.605$, respectively.Comment: 4 pages, 2 figure

Hard ellipsoids: analytically approaching the exact overlap distance

Following previous work (JCP 134, 201103 (2011)), the replica exchange Monte Carlo technique is used to produce the equation of state of hard 1:5 aspect-ratio oblate ellipsoids for a wide density range. Here, in addition to the analytical approximation of the overlap distance given by Berne and Pechukas (BP) and the exact numerical solution of Perram and Wertheim, we tested a simple modification of the original BP approximation (MBP) which corrects the known T-shape mismatch of BP for all aspect-ratios. We found that the MBP equation of state shows a very good quantitative agreement with the exact solution. The MBP analytical expression allowed us to study size effects on the previously reported results. For the thermodynamic limit, we estimated the exact 1:5 hard ellipsoid isotropic-nematic transition at the volume fraction 0.343(3), and the nematic-solid transition in the volume fraction interval 0.592(6)-0.634(8).Comment: 10 pages, 6 figure

The electrical double layer for a fully asymmetric electrolyte around a spherical colloid: an integral equation study

The hypernetted chain/mean spherical approximation (HNC/MSA) integral equation is obtained and solved numerically for a totally asymmetric primitive model electrolyte around a spherical macroparticle. The ensuing radial distribution functions show a very good agreement when compared to our Monte Carlo and molecular dynamics simulations for spherical geometry and with respect to previous anisotropic reference HNC calculations in the planar limit. We report an analysis of the potential vs charge relationship, radial distribution functions, mean electrostatic potential and cumulative reduced charge for representative cases of 1:1 and 2:2 salts with a size asymmetry ratio of 2. Our results are collated with those of the Modified Gouy-Chapman (MGC) and unequal radius Modified Gouy-Chapman (URMGC) theories and with those of HNC/MSA in the restricted primitive model (RPM) to assess the importance of size asymmetry effects. One of the most striking characteristics found is that,\textit{contrary to the general belief}, away from the point of zero charge the properties of an asymmetric electrical double layer (EDL) are not those corresponding to a symmetric electrolyte with the size and charge of the counterion, i.e. \textit{counterions do not always dominate}. This behavior suggests the existence of a new phenomenology in the EDL that genuinely belongs to a more realistic size-asymmetric model where steric correlations are taken into account consistently. Such novel features can not be described by traditional mean field theories like MGC, URMGC or even by enhanced formalisms, like HNC/MSA, if they are based on the RPM.Comment: 29 pages, 13 figure

Eficiencia alimentaria en sistemas de producción de leche con pariciones concentradas al inicio del período de máximo crecimiento de la hierba

Twenty-six dairy farms having an area between 93,5 ha and 112,1 ha, and a herd ranging from 109 to 126 cows were sampled to evaluate feeding efficiency based on variations in calving compaction levels at the beginning of the highest grass growing season. These farms are affiliated to six livestock production centers from Camagüey and Jimaguayú and located at 21,5° N and 71,2° W, 93 m above sea level. Soils are classified as types 2 and 3 within the agroproductive category. Climate is humid tropical complementary to inland plains. The mean annual rainfall is 1095 mm with 67 % of rains between April and October. The dairy farms calving percentages from April to August were registered according to three patterns: PI = 43 - 56 %, PII = 58 - 68 %, PIII = 70 - 82 %. Performance of feeding efficiency indicators was better (p<0,05) for PIII with a higher calving compaction level showing values of 0,48 milk/forage tons and 0,44 milk tons/food tons/cow compared to values for PI and PII. In addition, fat + protein production also reached higher values for PIII (p<0,05), i.e., 94 kg/cow/and 106 kg/ha. Findings support that feeding process is more efficient when calving compaction levels are higher and pastures and forage nutritional utilization is also higher.El objetivo del trabajo fue evaluar la eficiencia alimentaria de seis cooperativas ganaderas de Camagüey y Jimaguayú con diferentes concentraciones de sus partos al inicio de la época de máximo crecimiento de la hierba. Se usó la información registrada en seis cooperativas de estos territorios, ubicados a los 21,50 Norte y 71,20 Oeste, aproximadamente a 93 msnm con suelos de categoría agroproductiva 2 y 3 en el período comprendido entre abril de 2002 y marzo de 2009. El clima es tropical húmedo de llanura interior, con 1 095 mm de precipitación anual y el 67 % de las lluvias ocurriendo entre abril y octubre. Las 26 vaquerías escogidas tienen un área entre 93,5 y 112,1 ha y un rango de 109 a 126 vacas. La conformación de los patrones fue el siguiente: PI= 43 a 56 % de partos entre abril y agosto; PII= 58 a 68 % de partos entre abril y agosto; PIII= 70 a 82 % entre abril y agosto. Los mejores indicadores de eficiencia alimentaria (P < 0,05) se obtuvieron en el PIII con mayor concentración de partos en ese período, que presenta valores de 0,48 t de leche/t de forraje y de 0,44 t de leche/t de alimento total/vaca frente a valores menores en el resto de lo patrones. La producción de grasa+proteínas alcanzó valores de 94 kg/vaca y 106 kg/ha en el PIII, superiores (P < 0,05) a los restantes patrones, lo cual es consecuencia favorable de la mayor concentración de pariciones y mejor aprovechamiento de los aportes nutricionales de los pastos y forrajes en su época de mayor crecimiento; esto hace más eficiente el proceso alimentario

Factores que pueden afectar la eficiencia bioeconómica y ambiental en sistemas estacionales cubanos de producción de leche (artículo reseña)

This review aims at assessing a number of factors possibly affecting bioeconomic and environmental efficiency in seasonal dairy farming systems to be implemented as an alternative to traditional annual ones. Researchers carried out from March 1988 to February 2011 about the performance to 210 dairy farms and even livestock dairy production centers from Camagüey, Ciego de Ávila, and other provinces were reviewed. Concerning statistical data, several factors were evaluated: world milk production, productivity and quality of tropical pastures and their association with consumption based on animal load, seasonal calving patterns for dairy cows as an alternative to annual calving patterns, evaluations of seasonal calving periods and time, advantages of body reserves mobility process in dairy cows, herd reproductive performance status and its effects on milk production, economy, and profitability, as well as the perspective of implementing this seasonal dairy farming systems. Results showed that seasonal milk production possibilities were scientifically and economically valid based on seasonal calving intensification levels over 60 % at the beginning of the rainy season. This is translated into potential savings in convertible currency by a marked decrease in imports of dairy products and concentrated foods supplies, a better utilization of pastures and forage as a cheaper animal food supply, lower production costs by a reduction in powder milk manufacture, and environmental benefits by diminishing negative impacts through technological changes.Se discuten posibles factores que pueden afectar la eficiencia bioeconómica de los sistemas lecheros que se desarrollen en el país como alternativa a la producción lechera anualizada tradicional. Se revisaron investigaciones de Camagüey, Ciego de Ávila y otras zonas del país, desde marzo de 1988 hasta febrero de 2011 en 210 fincas lecheras y de empresas. Se utilizaron estadísticas de producción mundial de leche, productividad y calidad de los pastos tropicales y sus relaciones con el consumo según la carga animal, los patrones de partos estacionales en vacas lecheras como alternativa a los patrones anualizados, la evaluación de períodos de ocurrencia y momentos de parto dentro de época; las ventajas del proceso de movilización de reservas corporales en vacas lecheras, el estatus reproductivo del rebaño y sus efectos sobre la producción láctea, su economía y rentabilidad, así como la perspectiva de implementación de estos sistemas estacionales como alternativa. Se confirman científica y económicamente las posibilidades de la producción estacional de leche con pariciones concentradas en más de 60 % al inicio de la etapa lluviosa, como alternativa viable y sostenible a la clásica producción de leche anualizada que practican los sistemas ganaderos en Cuba, con potenciales ahorros de moneda convertible por una menor importación de lácteos y alimentos concentrados, con ventajas ambientales por la mínima agresión al medio por esos cambios tecnológicos y la reducción de los costos de la fabricación nacional de leche en polvo

Baseline Inflammatory Status Reveals Dichotomic Immune Mechanisms Involved In Primary-Progressive Multiple Sclerosis Pathology

To ascertain the role of inflammation in the response to ocrelizumab in primary-progressive multiple sclerosis (PPMS).Multicenter prospective study including 69 patients with PPMS who initiated ocrelizumab treatment, classified according to baseline presence [Gd+, n=16] or absence [Gd-, n=53] of gadolinium-enhancing lesions in brain MRI. Ten Gd+ (62.5%) and 41 Gd- patients (77.4%) showed non-evidence of disease activity (NEDA) defined as no disability progression or new MRI lesions after 1 year of treatment. Blood immune cell subsets were characterized by flow cytometry, serum immunoglobulins by nephelometry, and serum neurofilament light-chains (sNfL) by SIMOA. Statistical analyses were corrected with the Bonferroni formula.More than 60% of patients reached NEDA after a year of treatment, regardless of their baseline characteristics. In Gd+ patients, it associated with a low repopulation rate of inflammatory B cells accompanied by a reduction of sNfL values 6 months after their first ocrelizumab dose. Patients in Gd- group also had low B cell numbers and sNfL values 6 months after initiating treatment, independent of their treatment response. In these patients, NEDA status was associated with a tolerogenic remodeling of the T and innate immune cell compartments, and with a clear increase of serum IgA levels.Baseline inflammation influences which immunological pathways predominate in patients with PPMS. Inflammatory B cells played a pivotal role in the Gd+ group and inflammatory T and innate immune cells in Gd- patients. B cell depletion can modulate both mechanisms.Copyright © 2022 Fernández-Velasco, Monreal, Kuhle, Meca-Lallana, Meca-Lallana, Izquierdo, Oreja-Guevara, Gascón-Giménez, Sainz de la Maza, Walo-Delgado, Lapuente-Suanzes, Maceski, Rodríguez-Martín, Roldán, Villarrubia, Saiz, Blanco, Diaz-Pérez, Valero-López, Diaz-Diaz, Aladro, Brieva, Íñiguez, González-Suárez, Rodríguez de Antonio, García-Domínguez, Sabin, Llufriu, Masjuan, Costa-Frossard and Villar

Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 $< p_{\rm{T}, assoc} < p_{\rm{T}, trig} <$ 5.0 GeV/$c$ is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range $|\eta|<0.9$. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

Measurements of multi-particle azimuthal correlations (cumulants) for charged particles in p-Pb and Pb-Pb collisions are presented. They help address the question of whether there is evidence for global, flow-like, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a $|\Delta \eta|$ gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high-multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of $v_{2}\{4\}$ to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find $v_{2}\{4\} \simeq v_{2}\{6\}\neq 0$ which is indicative of a Bessel-Gaussian function for the $v_{2}$ distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a $|\Delta\eta| > 1.4$ gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87

Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\eta| < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286