A metaheuristic approach for the repositioning problem in bike sharing systems (bss): a study case in Toluca, México

The impact of Bike Sharing Systems (BSS) in the world had experienced such success that nowadays most iconic cities in the world have adopted its own system. The particular characteristics of the user’s mobility in every city have not allowed developing a generalized procedure to operate the systems. Moreover, the lack of symmetry in the mobility patterns, and the dynamic users’ behavior lead to eventually “unbalance” the system, this is, to a lack of bikes at stations, and therefore bikes have to be repositioned to stations where effective demand is present, and there is no unified or scientifically supported methodology. In this paper we deal with a study case in Toluca city (Huizi system), in which the entity in charge of current operational activities wants to design a procedure scientifically based to perform repositioning daily activities at the minimum operational cost guarantying the availability of bikes for the users (service level). Due to operational requirements, this bi-objective problem was formulated using a dynamic scope and stated as a combinatorial optimization model and finally solved using a multi-objective evolutionary algorithm

Twisted Nano-optics: Manipulating Light at the Nanoscale with Twisted Phonon Polaritonic Slabs

Recent discoveries have shown that when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between their respective in-plane principal axes, the electronic properties of the coupled system can be dramatically altered. Here, we demonstrate that a similar concept can be extended to the optics realm, particularly to propagating polaritons, hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a polar vdW crystal (MoO3) supporting low-loss anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources (metal antennas). Our images reveal that under a critical angle the PhPs isofrequency curve (determining the PhPs momentum at a fixed frequency) undergoes a topological transition. Remarkably, at this angle, the propagation of PhPs is strongly guided along predetermined directions (canalization regime) with no geometrical spreading (diffraction-less). These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nano-imaging, (bio)-sensing, quantum applications and heat management

Electrospinning Alginate/Polyethylene Oxide and Curcumin Composite Nanofibers

© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/.Manufacturing a sodium alginate (SA) and polyethylene oxide (PEO) composite loaded with curcumin (CU) was accomplished in this study by using electrospinning. These composite nanofibers were crosslinked using trifluoroacetic acid (TFA) mechanically characterized along with the morphological properties of the composite nanofiber mesh. We were successful in manufacturing the composite nanofibers with a wide range of CU concentrations ranging from 10 to 40 wt%. Firstly, dissolved in a saturated water/CU solution it was added to SA/PEO blending, homogenized and electrospun. Mechanical properties were affected by both CU addition and the cross-linking process, resulting in a higher ultimate tensile stress (MPa) (from 4.3±2 to 15.1±2 at 10% CU) and Young modulus (GPa) (0.0076±0.003, 0.044±0.003 before and after TFA). CU was successfully encapsulated in the SA nanofibers and excellent mechanical properties were obtained. By using a biocompatible TFA crosslinking and the natural properties of alginate this nanofiber composite could potentially be used for filtering, environmental pollution control, food packaging and for tissue engineering.Peer reviewe

Impacto del uso de energia en el sector industrial de Chile; una estimacion a traves de funciones de produccion

72 p.La presente investigación tiene como objetivo determinar el impacto del uso de energía en el sector industrial de Chile, entendiendo para efectos de este estudio el uso de energía como el uso de electricidad, a través de una estimación de funciones de producción para la industria como un todo y para cada sector de ésta. Para llevar a cabo lo anterior es necesario determinar la participación relativa de la energía en base a una regresión. Para saber cuáles variables incluir en el modelo se hizo una revisión bibliográfica acerca de las funciones de producción, temas relacionados con la energía y sector manufacturero de Chile, así como también para conocer lo que se ha estudiado previamente por otros autores. Luego se recopila la información pertinente para la investigación de las bases de datos del Instituto Nacional de Estadísticas (INE), específicamente fueron extraídos desde la Encuesta Nacional Industrial Anual (ENIA) para el periodo 1998 – 2006. En cuanto a la metodología, la estimación de los coeficientes y por ende de las participaciones relativas de los factores de producción se realizó mediante una regresión lineal en base a una generalización de una función de producción del tipo Cobb - Douglas, lo que permitió determinar para cada factor productivo su nivel de significancia. Se obtiene como conclusión que para algunos sectores como fabricación de maquinarias y equipos, y fabricación de maquinarias y aparatos eléctricos la energía no tienen un impacto significativo en sus niveles de producción, por lo que ésta representa para ellos una contribución al proceso de manufactura, más que un factor productivo relevante a ser comparado como lo son para la industria las materias primas y el empleo. Para sectores como fabricación de metales comunes, fabricación de otros productos minerales no metálicos, y fabricación de sustancias y productos químicos; fabricación de productos de la refinación del petróleo existe una contribución más activa del uso de la energía en los niveles de producción

Towards a holistic indicator of flow disturbance impact: fish community size spectra

Fish size-spectra provide a simple synthetic metric to assess the effects of pressures on the overall function of river ecosystems. An exploration of the effects of hydrological pressures on this metric is addressed in order to test its sensitiveness as a potential holistic indicator of ecological integrity. A set of 652 sampling sites with individual fish length data were used to compare the size-spectra among unimpaired sites and sites only affected by hydrological pressures. The variation of size-spectra along a gradient of rheophily was also considered. Our results show that size spectra slopes are naturally steeper in rheophilic than in limnephilic reaches. According to this, hydrological alterations produce different responses in the fish community size spectra. Hydrologically impaired rheophilic reaches show an increase in the ecological efficiency (size spectra slope) but a decrease in community capacity (elevation of the size spectra), whereas limnephilic reaches experience a decrease in the ecological efficiency but an increase in the food-web capacity (increased elevation of the size spectra). Slight differences in the type of the hydrological alteration (e.g. water abstraction vs. hydropeaking) might explain these effects

A1298C polymorphism in the MTHFR gene predisposes to cardiovascular risk in rheumatoid arthritis

8 páginas, 1 figura, 3 tablas.-- et al.[Introduction]: We determined the contribution of the methylene tetrahydrofolate reductase (MTHFR) 677 C>T and 1298 A>C gene polymorphisms to the susceptibility to rheumatoid arthritis (RA). We also assessed whether these two MTHFR gene polymorphisms may be implicated in the development of cardiovascular (CV) events and subclinical atherosclerosis manifested by the presence of endothelial dysfunction, in a series of Spanish patients with RA. [Methods]: Six hundred and twelve patients fulfilling the 1987 American College of Rheumatology classification criteria for RA, seen at the rheumatology outpatient clinics of Hospital Xeral-Calde, Lugo and Hospital San Carlos, Madrid, were studied. Patients and controls (n = 865) were genotyped using predesigned TaqMan SNP genotyping assays. [Results]: No significant differences in allele or genotype frequencies for the MTHFR gene polymorphisms between RA patients and controls were found. Also, no association between the MTHFR 677 C>T polymorphism and CV events or endothelial dysfunction was observed. However, the MTHFR 1298 allele C frequency was increased in patients with CV events after 5 years (38.7% versus 30.3%; odds ratio = 1.45; 95% confidence interval = 1.00 to 2.10; P = 0.04) and 10 years (42.2% versus 31.0%; odds ratio = 1.62; 95% confidence interval = 1.08 to 2.43; P = 0.01) follow up. Moreover, patients carrying the MTHFR 1298 AC and CC genotypes had a significantly decreased flow-mediated endothelium-dependent vasodilatation (4.3 ± 3.9%) compared with those carrying the MTHFR 1298 AA genotype (6.5 ± 4.4%) (P = 0.005). [Conclusions]: Our results show that the MTHFR 1298 A>C gene polymorphism confers an increased risk for subclinical atherosclerosis and CV events in patients with RA.The present study was supported by two grants from Fondo de Investigaciones Sanitarias PI06-0024 and PS09/00748 (Spain). This work was partially supported by RETICS Program RD08/0075 (RIER) from the Instituto de Salud Carlos III.Peer reviewe

Relevance of Qualitative Research Approach in Evaluating Mental Health Interventions among Victims of Violence

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The Multi-Chamber Electronic Nose—An Improved Olfaction Sensor for Mobile Robotics

One of the major disadvantages of the use of Metal Oxide Semiconductor (MOS) technology as a transducer for electronic gas sensing devices (e-noses) is the long recovery period needed after each gas exposure. This severely restricts its usage in applications where the gas concentrations may change rapidly, as in mobile robotic olfaction, where allowing for sensor recovery forces the robot to move at a very low speed, almost incompatible with any practical robot operation. This paper describes the design of a new e-nose which overcomes, to a great extent, such a limitation. The proposed e-nose, called Multi-Chamber Electronic Nose (MCE-nose), comprises several identical sets of MOS sensors accommodated in separate chambers (four in our current prototype), which alternate between sensing and recovery states, providing, as a whole, a device capable of sensing changes in chemical concentrations faster. The utility and performance of the MCE-nose in mobile robotic olfaction is shown through several experiments involving rapid sensing of gas concentration and mobile robot gas mapping

The H-NS regulator plays a role in the stress induced by carbapenemase expression in acinetobacter baumannii

Disruption of the histone-like nucleoid structuring protein (H-NS) was shown to affect the ability of Gram-negative bacteria to regulate genes associated with virulence, persistence, stress response, quorum sensing, biosynthesis pathways, and cell adhesion. Here, we used the expression of metallo-β-lactamases (MBLs), known to elicit envelope stress by the accumulation of toxic precursors in the periplasm, to interrogate the role of H-NS in Acinetobacter baumannii, together with other stressors. Using a multidrug-resistant A. baumannii strain, we observed that H-NS plays a role in alleviating the stress triggered by MBL toxic precursors and counteracts the effect of DNA-damaging agents, supporting its role in stress response. IMPORTANCE Carbapenem-resistant A. baumannii (CRAB) is recognized as one of the most threatening Gram-negative bacilli. H-NS is known to play a role in controlling the transcription of a variety of different genes, including those associated with the stress response, persistence, and virulence. In the present work, we uncovered a link between the role of H-NS in the A. baumannii stress response and its relationship with the envelope stress response and resistance to DNA-damaging agents. Overall, we posit a new role of H-NS, showing that H-NS serves to endure envelope stress and could also be a mechanism that alleviates the stress induced by MBL expression in A. baumannii. This could be an evolutionary advantage to further resist the action of carbapenems.Fil: Huang, Fanny. California State University. College Of Natural Science And Mathematics; Estados UnidosFil: Fitchett, Noelle. California State University. College Of Natural Science And Mathematics; Estados UnidosFil: Razo Gutierrez, Chelsea. California State University. College Of Natural Science And Mathematics; Estados UnidosFil: Le, Casin. California State University. College Of Natural Science And Mathematics; Estados UnidosFil: Martinez, Jasmine. California State University. College Of Natural Science And Mathematics; Estados UnidosFil: Ra, Grace. California State University. College Of Natural Science And Mathematics; Estados UnidosFil: Lopez, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gonzalez, Lisandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Sieira, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Vila, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Bonomo, Robert A.. Louis Stokes Cleveland Va Medical Center; Estados Unidos. Case Western Reserve University School of Medicine; Estados UnidosFil: Ramirez, Maria Soledad. California State University. College Of Natural Science And Mathematics; Estados Unido