Numerical Simulation of Warm-air Drying of Mexican Softwood (Pinus pseudostrobus): An Empirical and Mechanistic Approach

In this work, the numerical simulation of Mexican softwood (Pinus pseudostrobus) drying is presented by solving a phenomenological model. The model was developed by considering the heat and mass balance in the representative elementary volume, which involves the solid, liquid and gas phases. We solved a system of partial differential equations by numerical factorization in COMSOL multiphysics 3.5a©. Three primary variables were solved: the moisture content, the temperature, and the dry-air mass. The numerical results were compared against both experimental data and a semi-empirical model (Characteristic Drying Curve) previously published. The warm-air drying of Mexican softwood was simulated on a one-dimensional basis by considering two experimental conditions: air flow temperature at 60 and 80 ºC. Relative humidity was not controlled in the tunnel dryer. Simulated drying kinetics showed good agreement with the experimental data

Gestor de solicitudes de mantenimiento utilizando un sistema web desarrollado a través de la aplicación de la metodología ágil FDD

El aplicar una metodología ágil, para el desarrollo de software en Web ayuda a su calidad. El presente artículo reporta el desarrollo de Sistema Web que agiliza el proceso de solicitudes de mantenimiento eléctrico en cualquier momento y desde cualquier lugar; a su vez ordena, agiliza y transparenta las asignaciones de trabajo, solicitudes de material y monitoreo de la solicitud del trabajo eléctrico, lo cual permite brindar un mejor servicio dentro de la institución. Este Sistema Web concentra en un único lugar la información que permite la generación de reportes oportunos que apoyen el proceso de toma de decisiones en mejora del proceso de solicitudes de mantenimiento eléctrico en la institución. El desarrollo de este Sistema Web fue aplicando la metodología ágil FDD (Feature Driven Development – Desarrollo Basado en Características). Esta metodología se centra más en obtener resultados, convirtiéndose en una metodología novedosa y fácil de implementar.Palabras Clave: Ingeniería de Software, Metodología ágil FDD, Sistema Web

Confianza y redes sociales en productores de hortalizas en San Luis Potosí, México

In this study, there were two objectives: a) analyzing the social networks of vegetable producers in the middle zone of San Luis Potosí, México, in order to determine their organization; and b) establishing the importance that trust has for business relations such as loaning money, asking for money or setting up a society. Surveys were applied to 35 producers, who referenced 170 names that were later concentrated into 39 producers. With the field information, symmetrical matrices were built to schematize the network structure, and three logistic regression models were formulated to establish the probability of intention for action based on trust. The results show the importance that proximity between actors has. It is concluded that different levels of trust explain the disposition to lending money, setting up a society and, to a lesser degree, asking for money on loan.En la presente investigación se tuvieron dos objetivos: a) analizar las redes sociales de los productores de hortalizas de la zona media de San Luis Potosí, México, a fin de determinar su organización; y b) establecer la importancia que tiene la confianza para las relaciones de negocios como prestar dinero, pedir dinero o hacer una sociedad. Se encuestó a 35 productores, que referenciaron 170 nombres que posteriormente se concentraron en 39 productores. Con la información de campo se construyeron matrices simétricas para esquematizar la estructura de la red y se formularon tres modelos de regresión logística para establecer la probabilidad de la intención de acción basada en la confianza. Los resultados muestran la importancia que tiene la proximidad entre actores. Se concluye que diferentes niveles de confianza explican la disposición a prestar dinero, hacer una sociedad y, en menor medida, a pedir dinero prestado

Nitrogen and Phosphorous Retention in Tropical Eutrophic Reservoirs with Water Level Fluctuations: A Case Study Using Mass Balances on a Long-Term Series

Nitrogen and phosphorous loading drives eutrophication of aquatic systems. Lakes and reservoirs are often effective N and P sinks, but the variability of their biogeochemical dynamics is still poorly documented, particularly in tropical systems. To contribute to the extending of information on tropical reservoirs and to increase the insight on the factors affecting N and P cycling in aquatic ecosystems, we here report on a long-term N and P mass balance (2003–2018) in Valle de Bravo, Mexico, which showed that this tropical eutrophic reservoir lake acts as a net sink of N (−41.7 g N m y) and P (−2.7 g P m y), mainly occurring through net sedimentation, equivalent to 181% and 68% of their respective loading (23.0 g N m y and 4.2 g P m y). The N mass balance also showed that the Valle de Bravo reservoir has a high net N atmospheric influx (31.6 g N m y), which was 1.3 times the external load and likely dominated by N fixation. P flux was driven mainly by external load, while in the case of N, net fixation also contributed. During a period of high water level fluctuations, the net N atmospheric flux decreased by 50% compared to high level years. Our results outlining water regulation can be used as a useful management tool of water bodies, by decreasing anoxic conditions and net atmospheric fluxes, either through decreasing nitrogen fixation and/or promoting denitrification and other microbial processes that alleviate the N load. These findings also sustain the usefulness of long-term mass balances to assess biogeochemical dynamics and its variability.This research was funded by UNAM, PAPIIT-IN207702 and CONACYT-SEMARNAT, C01-1125 projects to M.M-

Rising nutrient-pulse frequency and high UVR strengthen microbial interactions

Solar radiation and nutrient pulses regulate the ecosystem’s functioning. However, little is known about how a greater frequency of pulsed nutrients under high ultraviolet radiation (UVR) levels, as expected in the near future, could alter the responses and interaction between primary producers and decomposers. In this report, we demonstrate through a mesocosm study in lake La Caldera (Spain) that a repeated (press) compared to a one-time (pulse) schedule under UVR prompted higher increases in primary (PP) than in bacterial production (BP) coupled with a replacement of photoautotrophs by mixotrophic nanoflagellates (MNFs). The mechanism underlying these amplified phytoplanktonic responses was a dual control by MNFs on bacteria through the excretion of organic carbon and an increased top-down control by bacterivory. We also show across a 6-year whole-lake study that the changes from photoautotrophs to MNFs were related mainly to the frequency of pulsed nutrients (e.g. desert dust inputs). Our results underscore how an improved understanding of the interaction between chronic and stochastic environmental factors is critical for predicting ongoing changes in ecosystem functioning and its responses to climatically driven changes.This study was supported by the Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional (FEDER) (CGL2011-23681 and CGL2015-67682-R to PC), Ministerio de Medio Ambiente, Rural, y Marino (PN2009/067 to PC) and Junta de Andalucía (Excelencia projects P09-RNM-5376 and P12-RNM-327 to PC and JMMS, respectively). M.J.C. was supported by the Spanish Government “Formación de Profesorado Universitario” PhD grant (FPU12/01243) and I.D.-G. by the Junta de Andalucía “Personal Investigador en Formación” PhD grant (FPI RNM-5376). This work is in partial fulfillment of the Ph. D. thesis of M.J.C

Striatal interneurons in dissociated cell culture

In addition to the well-characterized direct and indirect projection neurons there are four major interneuron types in the striatum. Three contain GABA and either parvalbumin, calretinin or NOS/NPY/somatostatin. The fourth is cholinergic. It might be assumed that dissociated cell cultures of striatum (typically from embryonic day E18.5 in rat and E14.5 for mouse) contain each of these neuronal types. However, in dissociated rat striatal (caudate/putamen, CPu) cultures arguably the most important interneuron, the giant aspiny cholinergic neuron, is not present. When dissociated striatal neurons from E14.5 Sprague–Dawley rats were mixed with those from E18.5 rats, combined cultures from these two gestational periods yielded surviving cholinergic interneurons and representative populations of the other interneuron types at 5 weeks in vitro. Neurons from E12.5 CD-1 mice were combined with CPu neurons from E14.5 mice and the characteristics of striatal interneurons after 5 weeks in vitro were determined. All four major classes of interneurons were identified in these cultures as well as rare tyrosine hydroxylase positive interneurons. However, E14.5 mouse CPu cultures contained relatively few cholinergic interneurons rather than the nearly total absence seen in the rat. A later dissection day (E16.5) was required to obtain mouse CPu cultures totally lacking the cholinergic interneuron. We show that these cultures generated from two gestational age cells have much more nearly normal proportions of interneurons than the more common organotypic cultures of striatum. Interneurons are generated from both ages of embryos except for the cholinergic interneurons that originate from the medial ganglionic eminence of younger embryos. Study of these cultures should more accurately reflect neuronal processing as it occurs in the striatum in vivo. Furthermore, these results reveal a procedure for parallel culture of striatum and cholinergic depleted striatum that can be used to examine the function of the cholinergic interneuron in striatal networks

Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at s=0.9\sqrt{s}=0.9, 2.76 and 7 TeV

Measurements of the sphericity of primary charged particles in minimum bias proton--proton collisions at $\sqrt{s}=0.9$, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is linearized to be collinear safe and is measured in the plane perpendicular to the beam direction using primary charged tracks with $p_{\rm T}\geq0.5$ GeV/c in $|\eta|\leq0.8$. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity ($N_{\rm ch}$) is reported for events with different $p_{\rm T}$ scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low $N_{\rm ch}$, whereas the event generators show the opposite tendency. The combined study of the sphericity and the mean $p_{\rm T}$ with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.Comment: 21 pages, 9 captioned figures, 3 tables, authors from page 16, published version, figures from http://aliceinfo.cern.ch/ArtSubmission/node/308

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal