A concise guide to existing and emerging vehicle routing problem variants

Vehicle routing problems have been the focus of extensive research over the past sixty years, driven by their economic importance and their theoretical interest. The diversity of applications has motivated the study of a myriad of problem variants with different attributes. In this article, we provide a concise overview of existing and emerging problem variants. Models are typically refined along three lines: considering more relevant objectives and performance metrics, integrating vehicle routing evaluations with other tactical decisions, and capturing fine-grained yet essential aspects of modern supply chains. We organize the main problem attributes within this structured framework. We discuss recent research directions and pinpoint current shortcomings, recent successes, and emerging challenges

Postnatal development of the astrocyte perivascular MLC1/GlialCAM complex defines a temporal window for the gliovascular unit maturation

International audienc

Microfracturing and microporosity in shales

Shales are ubiquitous rocks in sedimentary basins, where their low permeability makes them efficient seals for conventional oil and gas reservoirs and underground waste storage repositories (waste waters, CO2, nuclear fuels). Moreover, when they contain organic matter, they form source rocks for hydrocarbons that may escape towards a more porous reservoir during burial, a process referred to as primary migration. And when the hydrocarbons cannot escape, these rocks can be exploited as oil or shale gas reservoirs. While the presence of fractures at the outcrop scale has been described, the existence of fractures at smaller scales, their link with microporosity, the mechanisms that created them, their persistence over geological times, and their effect on the petrophysical properties of shales represent scientific challenges for which drillings in various sedimentary basins over the past decades may hold timely key data. Here, we review and synthetize the current knowledge on how microfractures and micropores in shales can be imaged and characterized and how they control their anisotropic mechanical properties and permeability. One question is whether such microfractures, when observed in outcrops or in drilled core samples extracted from boreholes, are related to decompaction and do not exist at depth. Another question is whether veins observed in shales represent microfractures that were open long enough to have acted as flow paths across the formation. The mechanisms of microfracture development are described. Some have an internal origin (fracturing by maturation of organic matter, dehydration of clays) while others are caused by external factors (tectonic loading). Importantly, the amount of microfracturing in shales is shown to depend strongly on the content in 1) organic matter, and 2) strong minerals. The nucleation of microfractures depends on the existence of mechanical heterogeneities down to the nanometer scale. Their propagation and linkage to create a percolating network will depend on the presence of heterogeneities at the meso- to macro-scales. Such percolating microfracture networks could control both the long-term sealing capabilities of cap rocks and the further propagation of hydraulic fracturing cracks. Finally, possible areas of research for describing the mechanism of microfracture formation in greater detail and how this impacts the transport and mechanical properties of shales are also discussed

Fretting Corrosion Behavior of Additive Manufactured and Cryogenic-Machined Ti6Al4V for Biomedical Applications

Metal ion release, caused by synergistic effect of wear and corrosion, is one of the major concerns related to the prostheses lifetime. In this work, samples of additive manufactured Ti6Al4V are machined under dry cutting and cryogenic cooling conditions and their performances in terms of corrosion and fretting corrosion response are investigated. A wet and temperature-controlled apparatus equipped with an electro-chemical cell is designed and set-up in order to evaluate the fretting corrosion effect acting at the interfaces. The obtained results show that the cryogenic machining improves the corrosion and fretting corrosion behavior of the investigated additive manufactured Ti6Al4V

Trend in vegetational cover affected by fire in the Torres del Paine National Park

[EN] Torres del Paine National Park (PNTP) is characterized as a representative geographical area of the world’s ecosystems, containing high scenic beauty and wide variety of ecosystems. The aim of this work is to analyze the spatial and temporal trends of vegetation at PNTP using remote images from the Landsat platforms, the MOD13A3 product from the Moderate Resolution Imaging Spectroradiometer (MODIS), coverage maps surface Global Land cover Maps of ESA/CCI 2005 and 2010 and a land cover map of continental Chile of 2014. In addition, the products of Soil Moisture and Ocean Salinity (SMOS) and meteorological data from the Torres del Paine meteorological station were used to analyze the environmental conditions that presented the park while the fire occurred the years 2011-2012. To determine the magni­tude of the changes of vegetation affected by fire at PNTP a nonparametric trend analysis was use with the Normalized Difference Vegetation Index (NDVI) of MODIS from 2002 to 2016 and the Normalized Burn Ratio (NBR) for the fire occurred the year 2005 and the years 2011-2012. The results show that between both fires it is been affected more than 30.000 hectares of the national park, being the “Scrub” and “Forest” coverage the most affected due to the high level of severity and the low regeneration of the burn area (less than 56%). The soil moisture does not exceed 20% m3m-3 before the fire and the rainfall does not exceed 101 mm during the days of fire, which is related to an increase in the probability of propa­gation of the fire. In this work is possible to realize that remote sensing can be used in the fire management to regard the national parks with the objective of preserve and conserve the flora, fauna and scenic beauty of Chile.[ES] El Parque Nacional Torres del Paine (PNTP) se caracteriza por ser un área geográfica representativa de los ecosistemas del mundo, al contener una alta belleza paisajística y amplia diversidad de ecosistemas. El objetivo de este trabajo es analizar las tendencias espacio temporales de la vegetación en el PNTP mediante el uso de imágenes remo­tas de la plataforma Landsat, del sensor “Moderate Resolution Imaging Spectroradiometer” (MODIS), correspondientes al producto MOD13A3, los mapas de cobertura de superficie Global Land Cover Maps del ESA/CCI del año 2005 y 2010 y el mapa de cobertura de suelo de Chile continental del 2014. Además, se utilizaron los productos de “Soil Moisture and Ocean Salinity” (SMOS), y datos meteorológicos de la estación meteorológica Torres del Paine para analizar las condiciones ambientales que presentó el parque mientras ocurría el incendio de los años 2011-2012. Para determinar la magnitud de los cambios de la vegetación afectada por incendio del PNTP se realizó un análisis no paramétrico de la tendencia del índice “Normalized Difference Vegetacion Index” (NDVI) de MODIS en el periodo 2002 a 2016 y el índice “Normalized Burn Ratio” (NBR) para los incendios de los años 2005 y 2011-2012. Los resultados muestran que los incendios 2005 y 2011-2012 afectaron a más de 30.000 hectáreas del Parque Nacional, siendo las coberturas de “Matorral” y “Bosque” las más afectadas debido a su alto nivel de severidad y su regeneración menor al 56% de la superficie afectada. En cuanto a la humedad de suelo esta no supera los 20% m3m–3 antes del incendio y las precipitaciones no superan los 101 mm durante los días de incendio lo que se relaciona con un aumento en las probabilidades de propagación del incendio. En este trabajo se evidencia que la teledetección puede ser utilizada en la gestión de incendios y así resguardar los parques nacionales con el fin de preservar y conservar la flora, fauna y belleza paisajística de Chile.Gracias al proyecto Conicyt – Fondecyt Iniciación 11130359 “Estimating the Surface soil moisture at regional scale by using a synergic optical-passive microwave approach and remote sensing data”, a United States Geological Survery (USGS) por el libre acceso a los datos Landsat-5 TM, Landsat-7 ETM+ y Landsat-8 OLI, a la National Aeronautics and Space (NASA) por los productos MODIS y la Dra. María Piles por los productos de humedad de suelo SMOS.Rivera, C.; Mattar, C.; Durán-Alarcón, C. (2017). Tendencia de la cobertura vegetacional afectada por incendios en el Parque Nacional Torres del Paine. Revista de Teledetección. (50):71-87. https://doi.org/10.4995/raet.2017.7422SWORD71875

Effect of photoperiod and host distribution on the horizontal transmission of Isaria fumosorosea (Hypocreales: Cordycipitaceae) in greenhouse whitefly assessed using a novel model bioassay

A model bioassay was used to evaluate the epizootic potential and determine the horizontal transmission efficiency of Isaria fumosorosea Trinidadian strains against Trialeurodes vaporariorum pharate adults under optimum conditions (25±0.5°C, ~100% RH) at two different photoperiods. Untreated pharate adults were arranged on laminated graph paper at different distributions to simulate varying infestation levels on a leaf surface. Four potential hosts were located 7, 14 and 21 mm away from a central sporulating cadaver simulating high, medium and low infestation levels, respectively. Percent hosts colonized were recorded 7, 12, 14 and 21 days post-treatment during a 16- and 24-h photophase. After 21 days, mean percent hosts colonized at the highest, middle and lowest infestation levels were 93 and 100%, 22 and 58%, 25 and 39% under a 16- and 24-h photophase, respectively. From the results, it was concluded that the longer the photophase, the greater the percentage of hosts colonized, and as host distance increased from the central sporulating cadaver, colonization decreased. The use of this novel model bioassay technique is the first attempt to evaluate the epizootic potential and determine the horizontal transmission efficiency of I. fumosorosea Trinidadian strains under optimal environmental conditions at different photoperiods. This bioassay can be used to assess horizontal transmission efficiency for the selection of fungi being considered for commercial biopesticide development

Intuitive Eating Behavior, Diet Quality and Metabolic Health in the Postpartum in Women with Gestational Diabetes

Little is known regarding intuitive eating (IE), diet quality and adherence. We investigated the associations between IE, diet quality and metabolic health after gestational diabetes (GDM), who have an increased diabetes risk. Data from 179 women with GDM from MySweetheart trial (NCT02872974) were analyzed. IE was assessed using the eating for physical rather than emotional reasons (EPR) and reliance on hunger and satiety cues (RHSC) subscales of the French Intuitive Eating Scale-2. Metabolic outcomes included weight, central body fat and insulin resistance. Diet quality was calculated using the Alternative Health Eating Index (AHEI) and compliance with national recommendations was evaluated. Both IE subscales were associated with lower BMI and fat mass (BIA) at 1-year postpartum (all p ≤ 0.034). The EPR subscale inversely correlated with fat mass (DXA) and visceral adipose tissue (both p ≤ 0.028), whereas RHSC with higher insulin sensitivity (Matsuda, p = 0.034). RHSC during pregnancy predicted increased AHEI (p = 0.043) at 1-year postpartum, whilst EPR predicted lower fat mass and insulin resistance (HOMA-IR) (all p ≤ 0.04). In longitudinal analyses, both subscales were associated with increased adherence to dairy and fiber intake recommendations (both p ≤ 0.023). These data suggest IE may be an interesting approach to improve diet quality and metabolic outcomes in women with GDM