1,473 research outputs found
Vehicle routing for public transport with adapted simulated annealing
This paper presents an Adapted Simulated Annealing (ASA) algorithm to solve an instance of the vehicle routing problem (VRP): the intercity public transport problem (IPTP). This combinatorial optimization problem was effectively solved by means of a robust method. Its performance was achieved thanks to the incorporation of an auxiliary memory and a novel choice of the neighbours. The model is based on initial random solutions capable of generating appropriate bus routes and frequencies in a large solution space. We have established a search strategy that provides excellent responses at the process level. The intercity line linking Bahía Blanca and Punta Alta was chosen with the intention of evaluating ASA performance. The real traffic-behavior has been represented by means of the simulation software called SUMO. The computational results clearly indicate that the proposed approach constitutes an improvement in the ability to search for high quality solutions that facilitates the convergence.Fil: Rodriguez, D. A.. Universidad Nacional de Salta. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Laboratorio de Investigación y Desarrollo en Computación Científica; ArgentinaFil: Olivera, Ana Carolina. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Laboratorio de Investigación y Desarrollo en Computación Científica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Brignole, Nélida Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Laboratorio de Investigación y Desarrollo en Computación Científica; Argentin
Stable p-branes in Chern-Simons AdS supergravities
We construct static codimension-two branes in any odd dimension D, with
negative cosmological constant, and show that they are exact solutions of
Chern-Simons (super)gravity theory for (super)AdS coupled to external sources.
The stability of these solutions is analyzed by counting the number of
preserved supersymmetries. It is shown that static massive (D-3)-branes are
unstable unless some suitable gauge fields are added and the brane is extremal.
In particular, in three dimensions, a 0-brane is recognized as the negative
mass counterpart of the BTZ black hole. For these 0-branes, we write explicitly
electromagnetically charged BPS states with various number of preserved
supersymmetries within the OSp(p|2) x OSp(q|2) supergroups. In five dimensions,
we prove that stable 2-branes with electromagnetic charge always exist for the
generic supergroup SU(2,2|N), where N is different than 4. For the special case
N=4, in which the CS supergravity requires the addition of a nontrivial gauge
field configuration in order to preserve maximal number of degrees of freedom,
we show for two different static 2-branes that they are BPS states (one of
which is the ground state), and from the corresponding algebra of charges we
show that the energy is bounded from below. In higher dimensions, our results
admit a straightforward generalization, although there are presumably more
solutions corresponding to different intersections of the elementary objects.Comment: 43 pages, revtex4.cls; v2: slight amendments and references added to
match published versio
The nutritive value of poultry diets containing sunflower meal supplemented by enzymes
The international limitations imposed on the utilization of meat and bone meals in animal diets, together with the increasing demand for soybean meal, create a necessity to search for other protein sources to economically balance compound feeds. In this regard it is important to note that sunflower is the best adapted high-protein crop available in some European regions and that is useful to use it in poultry farming as the replacement of other protein sources. Protein and many other nutrients are “imprisoned” to variable degrees, inside sunflower meal fibrous structures, and remain less available for digestion by the poultry’s own proteases and other endogenous enzymes. Added exogenous enzymes (phytase, hemicellulase, cellulase, carbohydrase, protease, etc.) offer a number of creative possibilities for breakdown and “liberation” of these nutrients, their easier digestion and absorption, and thus development of new nutritional standards and new diets formulation. Supplementation of poultry diets containing sunflower meal by different enzymes increasingly contribute to sustainable poultry farming by enhancing production efficiency, increasing the effectiveness of nutrient utilization and upgrading in environmental protection. [Projekat Ministarstva nauke Republike Srbije, br. III46012
Regulation of Reactive Oxygen Species and the Antioxidant Protein DJ-1 in Mastocytosis
Neoplastic accumulation of mast cells in systemic mastocytosis (SM) associates with activating mutations in the receptor tyrosine kinase KIT. Constitutive activation of tyrosine kinase oncogenes has been linked to imbalances in oxidant/antioxidant mechanisms in other myeloproliferative disorders. However, the impact of KIT mutations on the redox status in SM and the potential therapeutic implications are not well understood. Here, we examined the regulation of reactive oxygen species (ROS) and of the antioxidant protein DJ-1 (PARK-7), which increases with cancer progression and acts to lessen oxidative damage to malignant cells, in relationship with SM severity. ROS levels were increased in both indolent (ISM) and aggressive variants of the disease (ASM). However, while DJ-1 levels were reduced in ISM with lower mast cell burden, they rose in ISM with higher mast cell burden and were significantly elevated in patients with ASM. Studies on mast cell lines revealed that activating KIT mutations induced constant ROS production and consequent DJ-1 oxidation and degradation that could explain the reduced levels of DJ-1 in the ISM population, while IL-6, a cytokine that increases with disease severity, caused a counteracting transcriptional induction of DJ-1 which would protect malignant mast cells from oxidative damage. A mouse model of mastocytosis recapitulated the biphasic changes in DJ-1 and the escalating IL-6, ROS and DJ-1 levels as mast cells accumulate, findings which were reversed with anti-IL-6 receptor blocking antibody. Our findings provide evidence of increased ROS and a biphasic regulation of the antioxidant DJ-1 in variants of SM and implicate IL-6 in DJ-1 induction and expansion of mast cells with KIT mutations. We propose consideration of IL-6 blockade as a potential adjunctive therapy in the treatment of patients with advanced mastocytosis, as it would reduce DJ-1 levels making mutation-positive mast cells vulnerable to oxidative damage
The effect of subchronic supplementation with folic acid on homocysteine induced seizures
Influence of folic acid on the CNS is still unclear. Folate has a neuroprotective effect, while on the other hand excess folate can exacerbate seizures in epileptics. The aim of the present study was to examine the effect of subchronic administration of folic acid on behavioural and electroencephalographic (EEG) characteristics of DL homocysteine thiolactone induced seizures in adult rats. The activity of Na+/K+-ATPase and Mg2+-ATPase in different brain regions was investigated. Adult male Wistar rats were divided into groups: 1. Controls (C, 0.9% NaCl); 2. DL homocysteine-thiolactone 8.0 mmol/kg (H); 3. Subchronic supplementation with folic acid 5 mg/kg for 7 days (F) and 4. Subchronic supplementation with F + single dose of H (FH). Seizure behaviour was assessed by incidence, latency, number and intensity of seizure episodes. Seizure severity was described by a descriptive scale with grades 0–4. For EEG recordings, three gold-plated recording electrodes were implanted into the skull. Subchronic supplementation with folic acid did not affect seizure incidence, median number of seizure episodes and severity in FH, comparison with H (p > 0.05). The majority of seizure episodes in all groups were of grade 2. There were no significant differences in lethal outcomes at 24 h upon H injection in the FH vs. H group. The activity of Na+/K+-ATPase and Mg2+-ATPase was significantly increased in almost all examined structures in the FH vs. H group. Subchronic folic acid administration did not exacerbate H induced seizures and completely recovered the activity of ATPases
Report 43: Quantifying the impact of vaccine hesitancy in prolonging the need for Non-Pharmaceutical Interventions to control the COVID-19 pandemic
Vaccine hesitancy – a delay in acceptance or refusal of vaccines despite availability 1 – has the potential to threaten the successful roll-out of SARS-CoV-2 vaccines globally 2 . Here, we evaluate the potential impact of vaccine hesitancy on the control of the pandemic and the relaxation of non-pharmaceutical interventions (NPIs) by combining an epidemiological model of SARS-CoV-2 transmission 3 with data on vaccine hesitancy from population surveys. Our findings suggest that the mortality over a 2-year period could be up to 8 times higher in countries with high vaccine hesitancy compared to an ideal vaccination uptake if NPIs are relaxed. Alternatively, high vaccine hesitancy could prolong the need for NPIs to remain in place. Addressing vaccine hesitancy with behavioural interventions is therefore an important priority in the control of the COVID-19 pandemic
Geometry and stability of spinning branes in AdS gravity
The geometry of spinning codimension-two branes in AdS spacetime is analyzed
in three and higher dimensions. The construction of non-extremal solutions is
based on identifications in the covering of AdS space by isometries that have
fixed points. The discussion focuses on the cases where the parameters of
spinning states can be related to the velocity of a boosted static
codimension-two brane. The resulting configuration describes a single spinning
brane, or a set of intersecting branes, each one produced by an independent
identification. The nature of the singularity is also examined, establishing
that the AdS curvature acquires one in the form of a Dirac delta distribution.
The stability of the branes is studied in the framework of Chern-Simons AdS
supergravity. A class of branes, characterized by one free parameter, are shown
to be stable when the BPS conditions are satisfied. In 3D, these stable branes
are extremal, while in higher dimensions, the BPS branes are not the extremal
ones.Comment: 40 pages, 6 figure
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