Análisis del impacto del lead time en los costos totales y el nivel de servicio para una cadena de suministro con diferentes estructuras de productos y horizonte rodante de planificación

El principal objetivo de la investigación es analizar y evaluar el impacto o efectos que tienen el lead time por parte de los proveedores o eslabón primario sobre el sistema de costos y el desempeño del nivel de servicio, para una cadena de suministro de tipo multinivel. El sistema de producción, representado por el segundo eslabón de la cadena, se planifica y se programa mediante un horizonte rodante, el cual se optimiza para cada periodo, teniendo en cuenta los periodos de replanificación y los periodos de congelamiento. Se consideran también en esta etapa, los niveles de inventario, las recepciones programadas, y la limitación de los recursos. A través del modelo matemático GMOP (Generic Materials & Operations Planning), se optimiza el plan de requerimientos de materiales, basándose en el concepto de Stroke y Skus, y otro factor, entre ellos; los tiempos de entrega y las variantes en las estructuras de ensamble de los productos. El tercer eslabón de la cadena está condicionada por la heterogeneidad de la demanda, basada en el índice de Gini y un coeficiente de variación que simula un entorno con incertidumbre. Con los resultados de la simulación, se efectúa un análisis de varianza, con el propósito de evaluar el comportamiento, e interacción de los factores de entrada sobre el comportamiento de los costos totales y el efecto bullwhip, medido a través del nivel de servicio del sistemaThe main objective of the research is to analyze and evaluate the impact or effects of the waiting time on the part of suppliers or the primary language on the cost system and the performance of the service level, for a supply chain of type multilevel. The production system, the second link in the chain, the program is based on a rolling horizon, which is optimized for each period, taking into account the replanning periods and the freezing periods. Inventory levels, scheduled receptions, and limitation of resources are also considered in this stage. Through the mathematical model GMOP (Generic Materials and Operations Planning), the material requirements plan is optimized, the results in the concept of Stroke and Skus, and another factor, among them; Delivery times and variants in the structures of all the products. The third link in the chain is conditioned by the heterogeneity of the demand, based on the Gini index and the coefficient of variation that simulates an environment with uncertainty. With the results of the simulation, an analysis of the variance is carried out, with the purpose of evaluating the behavior, and the interaction of the factors of the entrance on the behavior of the total costs and the effect of the dome, the measured through of the service level of the syste

Multi-product biorefinery from Arthrospira platensis biomass as feedstock for bioethanol and lactic acid production

With the aim to reach the maximum recovery of bulk and specialty bioproducts while minimizing waste generation, a multi-product biorefinery for ethanol and lactic acid production from the biomass of cyanobacterium Arthrospira platensis was investigated. Therefore, the residual biomass resulting from different pretreatments consisting of supercritical fluid extraction (SF) and microwave assisted extraction with non-polar (MN) and polar solvents (MP), previously applied on A. platensis to extract bioactive metabolites, was further valorized. In particular, it was used as a substrate for fermentation with Saccharomyces cerevisiae LPB-287 and Lactobacillus acidophilus ATCC 43121 to produce bioethanol (BE) and lactic acid (LA), respectively. The maximum concentrations achieved were 3.02 ± 0.07 g/L of BE by the MN process at 120 rpm 30 °C, and 9.67 ± 0.05 g/L of LA by the SF process at 120 rpm 37 °C. An economic analysis of BE and LA production was carried out to elucidate the impact of fermentation scale, fermenter costs, production titer, fermentation time and cyanobacterial biomass production cost. The results indicated that the critical variables are fermenter scale, equipment cost, and product titer; time process was analyzed but was not critical. As scale increased, costs tended to stabilize, but also more product was generated, which causes production costs per unit of product to sharply decrease. The median value of production cost was US$1.27 and US$ 0.39, for BE and LA, respectively, supporting the concept of cyanobacterium biomass being used for fermentation and subsequent extraction to obtain ethanol and lactic acid as end products from A. platensis

Pautas de socialización e historia de vida de mujeres trabajadoras sexuales de la ciudad de Santa Marta Magdalena

Uno de los fenómenos sociales más antiguos de la humanidad, conocido a través de todos los tiempos es el comercio sexual, el cual ha sido poco estudiado, quizás por el tabú que rodea a los fenómenos ligados a la sexualidad humana, la prostitución fue cuidadosamente organizada y reglamentada. Por lo mencionado anteriormente, la formación sexual no puede esperar para comenzar cuando ya se atraviesan los umbrales de la adolescencia. La pareja tiene la obligación en primera instancia de comenzar la formación de su hijo desde el nacimiento le sigue en el orden la familia y la comunidad, encargadas de la socialización del niño desde antes de que comience su adaptación para la vida académica, con el ingreso al preescolar a la edad de 3 años. Es una responsabilidad ineludible ya que el joven a los 15 años prácticamente ha asimilado casi todos los valores que determinan su formación. Experiencia sabernos que esto ocurre demasiado tarde, cuando algunos ya han sido víctima del abuso sexual o están pagando las consecuencias de su ignorancia al respecto, viéndose obligados a legalizar la pareja o retirarse del plantel para responsabilizarse por una paternidad o maternidad no deseada

Microfluidics on the fly: Inexpensive rapid fabrication of thermally laminated microfluidic devices for live imaging and multimodal perturbations of multicellular systems

Microfluidic devices provide a platform for analyzing both natural and synthetic multicellular systems. Currently, substantial capital investment and expertise are required for creating microfluidic devices using standard soft-lithography. These requirements present barriers to entry for many nontraditional users of microfluidics, including developmental biology laboratories. Therefore, fabrication methodologies that enable rapid device iteration and work “out-of-the-box” can accelerate the integration of microfluidics with developmental biology. Here, we have created and characterized low-cost hybrid polyethylene terephthalate laminate (PETL) microfluidic devices that are suitable for cell and micro-organ culture assays. These devices were validated with mammalian cell lines and the Drosophila wing imaginal disc as a model micro-organ. First, we developed and tested PETLs that are compatible with both long-term cultures and high-resolution imaging of cells and organs. Further, we achieved spatiotemporal control of chemical gradients across the wing discs with a multilayered microfluidic device. Finally, we created a multilayered device that enables controllable mechanical loading of micro-organs. This mechanical actuation assay was used to characterize the response of larval wing discs at different developmental stages. Interestingly, increased deformation of the older wing discs for the same mechanical loading suggests that the compliance of the organ is increased in preparation for subsequent morphogenesis. Together, these results demonstrate the applicability of hybrid PETL devices for biochemical and mechanobiology studies on micro-organs and provide new insights into the mechanics of organ development

A Cautionary Tale: MARVELS Brown Dwarf Candidate Reveals Itself To Be A Very Long Period, Highly Eccentric Spectroscopic Stellar Binary

We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R ~ <30,000), this particular stellar binary mimics a single-lined binary with an RV signal that would be induced by a brown dwarf companion (Msin(i)~50 M_Jup) to a solar-type primary. At least three properties of this system allow it to masquerade as a single star with a very low-mass companion: its large eccentricity (e~0.8), its relatively long period (P~238 days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight (omega~189 degrees). As a result of these properties, for ~95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e~0.3). Only during the ~5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of ~15 km/s reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.Comment: 16 pages, 11 figures, 6 table

Very Low-Mass Stellar and Substellar Companions to Solar-Like Stars from MARVELS I: A Low Mass Ratio Stellar Companion to TYC 4110-01037-1 in a 79-day Orbit

TYC 4110-01037-1 has a low-mass stellar companion, whose small mass ratio and short orbital period are atypical amongst solar-like (Teff ~< 6000 K) binary systems. Our analysis of TYC 4110-01037-1 reveals it to be a moderately aged (~<5 Gyr) solar-like star having a mass of 1.07 +/- 0.08 MSun and radius of 0.99 +/- 0.18 RSun. We analyze 32 radial velocity measurements from the SDSS-III MARVELS survey as well as 6 supporting radial velocity measurements from the SARG spectrograph on the 3.6m TNG telescope obtained over a period of ~2 years. The best Keplerian orbital fit parameters were found to have a period of 78.994 +/- 0.012 days, an eccentricity of 0.1095 +/- 0.0023, and a semi-amplitude of 4199 +/- 11 m/s. We determine the minimum companion mass (if sin i = 1) to be 97.7 +/- 5.8 MJup. The system's companion to host star mass ratio, >0.087 +/- 0.003, places it at the lowest end of observed values for short period stellar companions to solar-like (Teff ~< 6000 K) stars. One possible way to create such a system would be if a triple-component stellar multiple broke up into a short period, low q binary during the cluster dispersal phase of its lifetime. A candidate tertiary body has been identified in the system via single-epoch, high contrast imagery. If this object is confirmed to be co-moving, we estimate it would be a dM4 star. We present these results in the context of our larger-scale effort to constrain the statistics of low mass stellar and brown dwarf companions to FGK-type stars via the MARVELS survey.Comment: 22 pages; accepted in A

MARVELS-1: A face-on double-lined binary star masquerading as a resonant planetary system; and consideration of rare false positives in radial velocity planet searches

We have analyzed new and previously published radial velocity observations of MARVELS-1, known to have an ostensibly substellar companion in a ~6- day orbit. We find significant (~100 m/s) residuals to the best-fit model for the companion, and these residuals are naively consistent with an interior giant planet with a P = 1.965d in a nearly perfect 3:1 period commensuribility (|Pb/Pc - 3| < 10^{-4}). We have performed several tests for the reality of such a companion, including a dynamical analysis, a search for photometric variability, and a hunt for contaminating stellar spectra. We find many reasons to be critical of a planetary interpretation, including the fact that most of the three-body dynamical solutions are unstable. We find no evidence for transits, and no evidence of stellar photometric variability. We have discovered two apparent companions to MARVELS-1 with adaptive optics imaging at Keck; both are M dwarfs, one is likely bound, and the other is likely a foreground object. We explore false-alarm scenarios inspired by various curiosities in the data. Ultimately, a line profile and bisector analysis lead us to conclude that the ~100 m/s residuals are an artifact of spectral contamination from a stellar companion contributing ~15-30% of the optical light in the system. We conclude that origin of this contamination is the previously detected radial velocity companion to MARVELS-1, which is not, as previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit.Comment: ApJ 770, 119. 24 pp emulate ApJ style, 12 figures (One is very large). v2: corrects two (important!) errors: A priori chance of this alignment or worse is 0.1% (not 0.01%) and the primary has THREE total companions (not four

RESPOSTA IMUNE INESPECÍFICA DE ANIMAIS ECTOTÉRMICOS ANTÁRTICOS SOB TEMPERATURAS POLARES

This review presents data on nonspecific immune system of Antarctic metazoans poekiloterms. The phagocytosis, inflammation and wound repair were analysed in Antarctic animals, the big head fish (Notothenia coriiceps = N. neglecta), Antarctic starfish (Odontaster validus) and in Antarctic sea urchin (Sterechinus neumayeri).Esta revisão tem por objetivo apresentar os dados sobre a imunidade inespecífica de metazoários pecilotérmicos antárticos obtidos por nosso grupo de pesquisa com animais antárticos. Trataremos em particular dos processos de fagocitose, inflamação e cicatrização em peixes antárticos popularmente chamados “cabeçudas” (Notothenia coriiceps = N. neglecta), em estrelas-do-mar antárticas (Odontaster validus) e em ouriços-do-mar antárticos (Sterechinus neumayeri)