Metodología para determinar atributos y métricas de calidad en sistemas hipermedia adaptativos educativos basados en estilos de aprendizaje

Este trabajo es una propuesta metodológica para determinar atributos y métricas de calidad en sistemas hipermedia adaptativos educativos basados en estilos de aprendizaje, específicamente en los estilos activo, reflexivo, teórico y pragmático. Estos atributos y métricas están referidos únicamente a la interacción del usuario-estudiante con el sistema, es decir, desde la óptica puramente educativa y no desde el punto de vista de la herramienta informática como tal. Para ello comienza su análisis desde las características del estilo de aprendizaje y a partir de ellas se procede al establecimiento de los atributos de acuerdo a las estrategias instruccionales que le correspondan. Finalmente, se definen las métricas necesarias para cada uno de los atributos, estableciendo el o los tipos de variables que involucran, sus unidades de medida y escalas. De esta manera se desarrolla una metodología de cascada de determinación de atributos y métrica

Behavior and performance of BIM users in a collaborative work environment

Collaborative work in Building Information Modeling (BIM) projects is frequentlyunderstood as the interaction of modelers in an asynchronous way through modification requests orvia e-mail/telephone. However, alternative work methodologies based on creating a common andsynchronous environment allow solving issues instantaneously during the design process. This studyaimed to analyze the behavior and performance of BIM users with different specialties who weresubjected to an experimental exercise in a collaborative environment. For this purpose, a processwas devised to collect, sort, and select the data from the log files generated by the BIM software.A timeline of the experiment was populated with data on the intensity and types of commands usedby each specialist, which allowed determining behavioral patterns, preferred commands, indicators oftheir experience, further training needs, and possible strategies for improving the team’s performance.In the experiment, the mechanical designer ’s performance was 49% and the rest approximately 64%,with respect to that of the architect. An average rate of 1.66 necessary or auxiliary commands foreach contributory command was detected. The average performance was 200–400 commands perhour, which intensified by the end of the experiment. Further training needs were detected for theplumbing designer to reduce the use of backwards commands. Conversely, the electrical designershowed a positive evolution regarding this aspect during the experiment. The analysis methods heredescribed become useful for the aforementioned purposes. Nevertheless, combinations with methodsfrom existing research might improve the outcomes and therefore the specificity of recommendation

Lysosomal vitamin E accumulation in Niemann–Pick type C disease

AbstractNiemann–Pick C disease (NPC) is a neuro-visceral lysosomal storage disorder mainly caused by genetic defects in the NPC1 gene. As a result of loss of NPC1 function large quantities of free cholesterol and other lipids accumulate within late endosomes and lysosomes. In NPC livers and brains, the buildup of lipids correlates with oxidative damage; however the molecular mechanisms that trigger it remain unknown. Here we study potential alterations in vitamin E (α-tocopherol, α-TOH), the most potent endogenous antioxidant, in liver tissue and neurons from NPC1 mice. We found increased levels of α-TOH in NPC cells. We observed accumulation and entrapment of α-TOH in NPC neurons, mainly in the late endocytic pathway. Accordingly, α-TOH levels were increased in cerebellum of NPC1 mice. Also, we found decreased mRNA levels of the α-TOH transporter, α-Tocopherol Transfer Protein (α-TTP), in the cerebellum of NPC1 mice. Finally, by subcellular fractionation studies we detected a significant increase in the hepatic α-TOH content in purified lysosomes from NPC1 mice. In conclusion, these results suggest that NPC cells cannot transport vitamin E correctly leading to α-TOH buildup in the endosomal/lysosomal system. This may result in a decreased bioavailability and impaired antioxidant function of vitamin E in NPC, contributing to the disease pathogenesis

Characterization of whitebait (Galaxias maculatus) respiratory rates to optimize intensive culture carrying capacities

Galaxias maculatus is an osmeriform native fish of the Southern Hemisphere, in which the crystalline larvae is considered as a luxury delicacy, for this reason, it has been commercially exploited in Chile, Argentina and New Zealand. However, the fisheries have been rapidly decreasing due to the overexploitation and the predation of introduced species. Because of these events, there is a need to determine a carrying capacity for an intensive fish culture. In order to optimize stocking densities for fish culture, this paper proposes objectives to determine oxygen consumption (OC) rates, dissolved oxygen concentrations that produce signs of hypoxia and the average time elapsed between food intake and peak OC in G. maculatus. In the oxygen experiments under routine metabolism conditions, we found that G. maculatus adults and whitebait showed signs of asphyxia at dissolved oxygen concentrations between 1.3 and 2.2mgL-1 and that adults tolerated dissolved oxygen levels as low as 1.3mgL-1. The results showed that G. maculatus individuals with an average weight of 0.04g consumed 0.048mgO2h-1, whereas individuals with an average weight of 1.4g consumed 0.345mgO2h-1. Galaxias maculatus increased the OC rate by 31%, from 0.39 to 0.51mgO2h-1g-1, occurring 14min after food intake. The carrying capacities for industrial cultures of G. maculatus, were estimated using an allometric equation (OC=0.2363 ×W0.612), a water flow rate of 1m3h-1 and an input oxygen concentration of 10mgL-1 at 12°C. The density culture of whitebait (4g) can be allowed to reach 8-11kgm-3; therefore, these stocking densities reduce the risk of hypoxia and mortality, ensuring the appropriate growth and feed conversion rates. © 2010 Blackwell Publishing Ltd

Structures and functions of mitochondrial ABC transporters

A small number of physiologically important ATP-binding cassette (ABC) transporters are found in mitochondria. Most are half transporters of the B group forming homodimers and their topology suggests they function as exporters. The results of mutant studies point towards involvement in iron cofactor biosynthesis. In particular, ABC subfamily B member 7 (ABCB7) and its homologues in yeast and plants are required for iron-sulfur (Fe-S) cluster biosynthesis outside of the mitochondria, whereas ABCB10 is involved in haem biosynthesis. They also play a role in preventing oxidative stress. Mutations in ABCB6 and ABCB7 have been linked to human disease. Recent crystal structures of yeast Atm1 and human ABCB10 have been key to identifying substrate-binding sites and transport mechanisms. Combined with in vitro and in vivo studies, progress is being made to find the physiological substrates of the different mitochondrial ABC transporters

Experimental study of an R1234ze(E)/R134a mixture (R450A) as R134a replacement

[EN] This work presents an experimental analysis of a non-flammable R1234ze(E)/R134a mixture (R450A) as R134a drop-in replacement. While R134a has a high GWP value (1430), the R450A GWP is only 547. The experimental tests are carried out in a vapour compression plant equipped with a variable-speed compressor. The replacement suitability has been studied combining different operating conditions: evaporation temperature, condensation temperature and the use of an internal heat exchanger (IHX). The drop-in cooling capacity of R450A compared with R134a is 6% lower as average. R450A COP is even higher to those resulting with R134a (approximately 1%). The discharge temperature of R450A is lower than that of R134a, 2K as average. The IHX has a similar positive influence on the energy performance of both fluids. In conclusion, R450A can be considered as a good candidate to replace R134a.The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte" for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".Mota Babiloni, A.; Navarro Esbri, J.; Barragán Cervera, Á.; Moles Ribera, F.; Peris Pérez, B. (2015). Experimental study of an R1234ze(E)/R134a mixture (R450A) as R134a replacement. International Journal of Refrigeration. 51:52-58. doi:10.1016/j.ijrefrig.2014.12.010S52585

Drop-in energy performance evaluation of R1234yf and R1234ze(E) in a vapour compression system as R134a replacements

[EN] This paper presents an energy performance evaluation of two low-GWP refrigerants, R1234yf and R1234ze(E), as drop-in replacements for R134a. Tests are carried out in a monitored vapor compression system combining different values of evaporation and condensation temperature, and without/with the adoption of an internal heat exchanger. The parameters analyzed are volumetric efficiency, cooling capacity and COP and they are presented taking R134a as baseline. Results show that without IHX the average volumetric efficiency for R1234yf and R1234ze is 4% and 5% lower compared with R134a. The cooling capacity obtained with R1234yf and R1234ze is reduced, with an average difference of 9% and 30% without IHX. Also, COP values are about 7% lower for R1234yf and 6% lower for R1234ze than those obtained using R134a. Finally, the use of an internal heat exchanger reduces the COP differences for both replacements. (C) 2014 Elsevier Ltd. All rights reserved.The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte" for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".Mota-Babiloni, A.; Navarro-Esbrí, J.; Barragán Cervera, Á.; Molés, F.; Peris, B. (2014). Drop-in energy performance evaluation of R1234yf and R1234ze(E) in a vapour compression system as R134a replacements. Applied Thermal Engineering. 71(1):259-265. https://doi.org/10.1016/j.applthermaleng.2014.06.056S25926571

Clinical trials in amyotrophic lateral sclerosis:a systematic review and perspective

Amyotrophic lateral sclerosis is a progressive and devastating neurodegenerative disease. Despite decades of clinical trials, effective disease modifying drugs remain scarce. To understand the challenges of trial design and delivery, we performed a systematic review of phase II, phase II/III and phase III amyotrophic lateral sclerosis clinical drug trials on trial registries and PubMed between 2008 and 2019. We identified 125 trials, investigating 76 drugs and recruiting more than 15000 people with amyotrophic lateral sclerosis. 90% of trials used traditional fixed designs. The limitations in understanding of disease biology, outcome measures, resources and barriers to trial participation in a rapidly progressive, disabling and heterogenous disease hindered timely and definitive evaluation of drugs in two-arm trials. Innovative trial designs, especially adaptive platform trials may offer significant efficiency gains to this end. We propose a flexible and scalable multi-arm, multi-stage trial platform where opportunities to participate in a clinical trial can become the default for people with amyotrophic lateral sclerosis

A review of refrigerant R1234ze(E) recent investigations

[EN] Climate change is demonstrated through global surface temperatures increase in the last century. To stop this phenomenon, new regulations that ban or tax greenhouse gas fluids (HFC among them) have been approved. In the medium term, only low-GWP refrigerants will be permitted in developed countries. HFO fluids and most used HFCs as refrigerants in HVACR systems possess similar thermophysical properties. Among them, one of the most promising is R1234ze(E). This refrigerant presents good environmental properties and can be used in most of HVACR applications, pure or mixed with HFC or natural refrigerants (mainly CO2). This paper collects the most relevant research about R1234ze(E) thermophysical and compatibility properties, heat transfer and pressure drop characteristics, and vapor compression system performance; separating those works that consider R1234ze(E) pure or blended. Once the available literature is analyzed, it can be concluded that pure R1234ze(E) is a good option only in new HVACR systems. Nevertheless, if it is combined with other refrigerants, the final GWP value is also considerably reduced, maintaining efficiency parameters at levels that allow them to replace R134a, R404A or R410A in existing systems with minor modifications.The authors thankfully acknowledge the “Ministerio de Educación, Cultura y Deporte” (Grant Number FPU12/02841) for supporting this work through “Becas y Contratos de Formación de Profesorado Universitario del Programa Nacional de Formación de Recursos Humanos de Investigación del ejercicio 2012”.Mota-Babiloni, A.; Navarro-Esbrí, J.; Molés, F.; Barragán Cervera, Á.; Peris, B.; Verdú Martín, GJ. (2016). A review of refrigerant R1234ze(E) recent investigations. Applied Thermal Engineering. 95:211-222. https://doi.org/10.1016/j.applthermaleng.2015.09.055S2112229