This paper proposes a new method to solve the multistage security-constrained transmission expansion planning problem, incorporating lines based on high-voltage alternating current (HVAC) and ...high-voltage direct current (HVDC) alternatives. A novel mixed-integer linear programming model, which incorporates transmission losses using a piecewise linearization, is presented. An efficient method to reduce the search space of the problem is developed to help in the solution process. Garver's 6-bus system and a modified Southern Brazilian system are used to show the precision and efficiency of the proposed approach. The tests are performed for cases with and without HVDC links and transmission losses. The results indicate that better expansion plans can be found by considering HVDC proposals in the expansion process. The promising trend of using HVDC lines in future networks to improve the reliability in the system is demonstrated.
The U.S. Food and Drug Administration's (FDA's) Center for Veterinary Medicine (CVM) has been investigating reports of pets becoming ill after consuming jerky pet treats since 2007. Renal failure ...accounted for 30% of reported cases. Jerky pet treats contain glycerin, which can be made from vegetable oil or as a byproduct of biodiesel production. Glycidyl esters (GEs) and 3-monochloropropanediol esters (3-MCPDEs) are food contaminants that can form in glycerin during the refining process. 3-MCPDEs and GEs pose food safety concerns, as they can release free 3-MCPD and glycidol in vivo. Evidence from studies in animals shows that 3-MCPDEs are potential toxins with kidneys as their main target. As renal failure accounted for 30% of reported pet illnesses after the consumption of jerky pet treats containing glycerin, there is a need to develop a screening method to detect 3-MCPDEs and GEs in glycerin. We describe the development of an ultra-high-pressure liquid chromatography/quadrupole time-of-flight (UHPLC/Q-TOF) method for screening glycerin for MCPDEs and GEs. Glycerin was extracted and directly analyzed without a solid-phase extraction procedure. An exact mass database, developed in-house, of MCPDEs and GEs formed with common fatty acids was used in the screening.
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The importance of immunoproteasomes to antigen presentation has been unclear because animals totally lacking immunoproteasomes had not been available. Having now developed mice lacking the three ...immunoproteasome catalytic subunits, we found that the dendritic cells of these mice had defects in presenting several major histocompatibility complex (MHC) class I epitopes. During viral infection in vivo, the presentation of a majority of MHC class I epitopes was markedly reduced in immunoproteasome-deficient animals compared with wild-type animals, whereas presentation of MHC class II peptides was unaffected. According to mass spectrometry, the repertoire of MHC class I-presented peptides was ∼50% different from that in wild-type mice, and these differences were sufficient to stimulate robust transplant rejection of wild-type cells in mutant mice. These results indicated that immunoproteasomes were more important in antigen presentation than previously thought.
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In some real power systems in Latin America, such as those in Brazil, Colombia and Ecuador, the final decision about when to carry out the preventive maintenance is made by the ISO (integrated system ...operator), in a centralized way. In such a scenario, an optimization model coupling generation maintenance scheduling (GMS) and hydrothermal dispatch (HTD) might lead to lower operation costs from the ISO’s perspective, leading to an optimal solution that might differ from the combined base maintenance schedule (BMS) proposed by the power generation companies. In this paper we develop a mathematical model coordinating the GMS with middle term HTD from the point of view of the ISO. The mathematical model proposed is a mixed integer linear programming (MILP) type that approaches the uncertainty in water inflows through multiple scenarios. The test system emulates a real scale hydrothermal system. The results obtained by the proposed model show operation cost reduction ranging from 5% to as much as 20%, when compared with the BMS proposed by the individual companies.
This project is presented as an innovative and clean alternative that optimizes the use of small areas for strawberry (Fragaria ananassa Duch) production in the department of Nariño. This research ...was conducted at the Centro Internacional de Producción Limpia Lope -SENA- Regional Nariño, with the aim of evaluating physical and chemical variables of organic substrates such as coconut fiber, rice husk, and their mixtures for strawberry (Fragaria ananassa Duch) variety Albión production in a hydroponic system. Six treatments and four repetitions were performed; the treatments were 100% rice husk, 70% rice husk and 30% coconut fiber mixture, 50% of each of the substrates used, a mixture of 70% coconut fiber and 30% rice husk, 100% coconut fiber, and a control in soil with plastic cover. A comparative analysis was made between the average values obtained in the initial stage and the final stage of the experiment, evaluating physical and chemical properties such as bulk density, real density, gravimetric moisture, granulometry, pH, and electrical conductivity. The experiment showed that taking initial and final measurements of the substrates allows adequate monitoring for optimal crop development since a substrate with a high percentage of particles in the sieve <0.25, electrical conductivities greater than 2000 µS.cm-1, and an increase in bulk density can produce salinization and compaction, negatively impacting the crop.
The success of assisted pollination in oil palm is essential for oil production, since it determines the amount of well-formed fruits; in this process, the pollen quality, expressed as viability and ...germinability, is of great importance. This work was carried out in the Salamanca Oleaginosas S.A. Laboratories, in order to determine the viability, germination and pollen tube growth of pollen grains of Guineensis, Amazon, Coari x Lame and Unipalma genotypes, stored during 0, 5, 15 and 30 days at room temperature, and -13 °C. Using an unrestrictedly randomized design with a factorial arrangement and four replications, the variables percentage of viability and germination, length and growth rate of the pollen tube were analyzed. Guineensis pollen had the highest germination and viability values, which ensure a good pollination efficiency, while the other cultivars had values below the recommended, although pollen tube growth of the few grains that germinated was similar to Guineensis.
Effective CD8(+) T cell responses depend on presentation of a stable peptide repertoire by MHC class I (MHC I) molecules on the cell surface. The overall quality of peptide-MHC I complexes (pMHC I) ...is determined by poorly understood mechanisms that generate and load peptides with appropriate consensus motifs onto MHC I. In this article, we show that both tapasin (Tpn), a key component of the peptide loading complex, and the endoplasmic reticulum aminopeptidase associated with Ag processing (ERAAP) are quintessential editors of distinct structural features of the peptide repertoire. We carried out reciprocal immunization of wild-type mice with cells from Tpn- or ERAAP-deficient mice. Specificity analysis of T cell responses showed that absence of Tpn or ERAAP independently altered the peptide repertoire by causing loss as well as gain of new pMHC I. Changes in amino acid sequences of MHC-bound peptides revealed that ERAAP and Tpn, respectively, defined the characteristic amino and carboxy termini of canonical MHC I peptides. Thus, the optimal pMHC I repertoire is produced by two distinct peptide editing steps in the endoplasmic reticulum.
This paper proposes a two-phase heuristic algorithm to solve the crew scheduling problem of the Megabus Bus Rapid Transit System. In the first stage, a division of the original schedules is performed ...using a recursive algorithm based on dynamic scheduling. In the second stage, work-shift construction based on graph theory is performed using a pairing algorithm (i.e., matching). The method is validated by applying it to the mass transit system of the Central Western Metropolitan Area (AMCO), operated by Integra SA, which serves 11 routes for a daily total of 2899 trips.
This paper presents a hybrid technique for solving the generation maintenance scheduling coordinated with middle term hydrothermal dispatch based on the Chu-Beasley genetic algorithm and linear ...programming. It takes into consideration the non-linearity derived from the cost of the fuel for thermal power plants. The output of the genetic algorithm is a proposal for the start week of the generation maintenance plan that minimises the hydrothermal dispatch cost. This work has two main contributions: on one hand proposing a solution that integrates hydrothermal dispatch and maintenance scheduling in a single model, therefore a new mathematical model and, on the other hand the proposed solution applies a specialised genetic algorithm that has not been applied before to solve this problem. The test system to validate the methodology is composed of three hydro plants and two thermal plants split into 22 generation units, considering three types of preventive maintenance, in a planning term of one year (52 weeks). This methodology combines an exact technique and a specialised genetic algorithm, which favours convergence.
Este dossier en LITERATURA – SOCIEDAD/CULTURA: Sociología de la Literatura, Sociocrítica y abordajes socioculturales de las estéticas literarias es un homenaje a la Dra. Hélène Pouliquen y el ...importante legado teórico y pedagógico que ha dejado en varias generaciones de literatos de la Universidad Nacional de Colombia, el Instituto Caro y Cuervo, y la Universidad Javeriana en torno a estas disciplinas a partir de sus clases, trayectoria investigativa y publicaciones. …
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