346 research outputs found

    Physiology\u27s influence on the thermal comfort of the occupants: A study in Ensenada, Baja California

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    INTRODUCTION: Thermal environment\u27s adverse conditions can significantly affect the performance, comfort and well-being of people, so this study aims to estimate the thermal comfort range from the cold period in Ensenada city, Baja California: February month, from different levels of metabolic activity: passive, moderate and intense. PURPOSE: This study seeks to identify the relationship between the people thermal perception, their metabolic activity and the physical or psychological sensations involved in the process of adaptation indoors. Thermal sensations are caused by several factors: 1) Physical stimuli of the thermal environment, 2) Activity metabolic, as well as the intensity with which it is performed, 3) Clothing, 4) Experience and 5) Human expectation. METHODS: Data collection was based on the application of questionnaires, which considered physiological, perceptual and environmental characteristics measurements. The study case is located in Ensenada city (temperate-dry bioclimate); with a target population that is within the range of 15-19 years old and 20-24 years old. It was decided to apply the assessments to university students of the Autonomous University of Baja California, who represent 60 % of the statewide student community. RESULTS: Estimated thermal comfort during the cold period resulted from 16.9 °C to 23.9 °C for occupants that exercising passive activity (0.8 met to 1.2 met), from 16.6 °C to 23.9 °C for moderate activity (1.2 met to 1.6 met); and 17.1 °C to 23.2 °C for those who exercised intense activity (2.0 met to 2.4 met). CONCLUSION: According to the aforementioned, it is possible to inform that occupants metabolic activity and, thereby the production of generated internal heat, exerts an influence in the thermal sensation that they perceive from immediate environment

    Emissions of Fe(II) and its kinetic of oxidation at Tagoro submarine volcano, El Hierro

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    The eruptive process that took place in October 2011 in the submarine volcano Tagoro off the Island of El Hierro and the subsequent degasification stage, five months later, have increased the concentration of TdFe(II) (Total dissolved iron(II)) in thewaters nearest to the volcanic edifice. In order to detect any variation in concentrations of TdFe(II) due to hydrothermal emissions, three cruiseswere carried out two years after the eruptive process in October 2013,March 2014 andMay 2015. The results fromthese cruises confirmed important positive anomalies in TdFe(II), which coincided with negatives anomalies in pHF,is (pH in free scale, at in situ conditions) located in the proximity of themain cone. Maximumvalues in TdFe(II) both at the surface, associated to chlorophyll a maximum, and at the sea bottom, were also observed, showing the important influence of organic complexation and particle re-suspension processes. Temporal variability studies were carried out over periods ranging from hours to days in the stations located over themain and two secondary cones in the volcanic edifice with positive anomalies in TdFe(II) concentrations and negative anomalies in pHF,is values. Observations showed an important variability in both pHF,is and TdFe(II) concentrations, which indicated the volcanic area was affected by a degasification process that remained in the volcano after the eruptive phase had ceased. Fe(II) oxidation kinetic studies were also undertaken in order to analyze the effects of the seawater properties in the proximities of the volcano on the oxidation rate constants and t1/2 (half-life time) of ferrous iron. The increased TdFe(II) concentrations and the low associated pHF,is values acted as an important fertilization event in the seawater around the Tagoro volcano at the Island of El Hierro providing optimal conditions for the regeneration of the area.En prens

    Modelo de competencia docente del profesor de medicina en la UNAM

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    El estudio presenta un modelo de competencia docente del profesor de medicina. Fue generado a partir de un modelo conceptual preexistente: a) dicho modelo se sometió al juicio de expertos quienes seleccionaron las competencias de mayor impacto; b) se construyó un perfil de competencias; c) se generó un instrumento basado en la opinión de los estudiantes y otro de autoevaluación; d) ambos fueron validados por 18 expertos en evaluación; e) se aplicó a 2,281 estudiantes y 107 profesores, obteniendo un comportamiento psicométrico adecuado que permitió establecer un modelo acorde a las tendencias actuales en evaluación del desempeño docente

    Variability of nutrients and carbon dioxide in the Antarctic Intermediate Water between 1990 and 2014

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    Antarctic Intermediate Water (AAIW) formation constitutes an important mechanism for the export of macronutrients out of the Southern Ocean that fuels primary production in low latitudes. We used quality-controlled gridded data from five hydrographic cruises between 1990 and 2014 to examine decadal variability in nutrients and dissolved inorganic carbon (DIC) in the AAIW (neutral density range 27 < γ n <  27.4) along the Prime Meridian. Significant positive trends were found in DIC (0.70 ± 0.4 μmol kg− 1 year− 1) and nitrate (0.08 ± 0.06 μ mol kg− 1 year− 1) along with decreasing trends in temperature (− 0.015 ± 0.01∘C year− 1) and salinity (− 0.003 ± 0.002 year− 1) in the AAIW. Accompanying this is an increase in apparent oxygen utilization (AOU, 0.16 ± 0.07 μ mol kg− 1 year− 1). We estimated that 75% of the DIC change has an anthropogenic origin. The remainder of the trends support a scenario of a strengthening of the upper-ocean overturning circulation in the Atlantic sector of the Southern Ocean in response to the positive trend in the Southern Annular Mode. A decrease in net primary productivity (more nutrients unutilized) in the source waters of the AAIW could have contributed as well but cannot fully explain all observed changes

    Significant Release of Dissolved Inorganic Nutrients From the Shallow Submarine Volcano Tagoro (Canary Islands) Based on Seven-Year Monitoring

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    Tagoro, the shallow submarine volcano that erupted south of El Hierro (Canary Islands, Spain) in October 2011, has been intensely monitored for over 7 years, from the early eruptive stage to the current degassing stage characterized by moderate hydrothermal activity. Here, we present a detailed study of the emissions of inorganic macronutrients (NO2– + NO3–, PO4, and Si(OH)4) comprising a dataset of over 3300 samples collected through three different sampling methodologies. Our results show a significant nutrient enrichment throughout the whole studied period, up to 8.8-fold (nitrate), 4.0-fold (phosphate), and 16.3-fold (silicate) in the water column, and larger enrichments of phosphate (10.5-fold) and silicate (325.4-fold), but not of nitrate, in the samples collected directly from the vents. We also provide some preliminary results showing ammonium (NH4+) concentrations up to 1.97 μM in the vent fluids as compared to 0.02 μM in the surrounding waters. Nutrient fluxes from the volcano during the degassing stage were estimated as 3.19 ± 1.17 mol m–2 year–1 (NO2– + NO3–), 0.02 ± 0.01 mol m–2 year–1 (PO4), and 0.60 ± 1.35 mol m–2 year–1 (Si(OH)4), comparable to other important nutrient sources in the region such as fluxes from the NW-African upwelling. Nutrient ratios were affected, with a minimum (NO3– + NO2–):PO4 ratio of 2.36:1; moreover, a linear correlation between silicate and temperature enabled the use of this nutrient as a mixing tracer. This study sheds light on how shallow hydrothermal systems impact the nutrient-poor upper waters of the ocean.En prens

    Reconstruction of the seasonal cycle of air–sea CO2 fluxes in the Strait of Gibraltar

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    The present study reports and discusses water surface fCO2 measurements from 36 cruises in the Strait of Gibraltar made over an eleven-year period (1997 to 2009). Underway measurements of sea surface CO2 fugacity (fCO2sw), sea surface temperature (SST) and sea surface salinity (SSS) compiled during the cruises were analysed and integrated into a single database which provided the resolution/sensitivity required for an examination of the seasonal variability of the fCO2sw; these data allowed the reconstruction of the climatological seasonal cycle for the year 2005. The seasonal cycle of both SST and SSS was found to be within the range of the thermohaline signature of the North Atlantic Surface Water, which is the main water mass that flows into the Mediterranean Sea through the Strait of Gibraltar at the surface. The seasonal distribution of fCO22005 was characterised by a monthly minimum value of 334 ± 12 μatm in May, followed by a gradual increase to a maximum of 385 μatm during late summer, due to the warming of surface waters. The spatial variability of fCO2sw observed in the area also indicated that superimposed phenomena, occurring at scales other than seasonal, could affect the dissolved CO2 distribution. In particular, intense vertical mixing processes generated by internal waves in this region may have an impact on the surface fCO2sw on a tidal scale. Seasonal CO2 cycle dynamics indicated that the surface waters of the Strait of Gibraltar acted as an atmospheric CO2 source during summer and autumn and a CO2 sink during winter and spring. When these sink/source strengths are integrated on an annual basis, the Strait of Gibraltar was close to equilibrium with atmospheric CO2, resulting in a neutral atmosphere-ocean exchange (− 0.06 ± 0.12 mol C m− 2 yr− 1).Funding for this work was provided by the CARBOOCEAN IP of the European Commission (511176GOCE) and by the Spanish Ministry of Education and Sciences through the Projects CAIBEX (CTM2007-66408) and (CTM2006-26206-E/MAR). Author Mercedes de la Paz acknowledges the financial support of the CSIC postdoctoral program JAE-Doc.Peer reviewe

    Sex-related differences of fatty acid-binding protein 4 and leptin levels in atrial fibrillation

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    Aims: Adiposity plays a key role in the pathogenesis of atrial fibrillation (AF). Our aim was to study the sex differences in adipokines levels according to AF burden. Methods and results: Two independent cohorts of patients were studied: (i) consecutive patients with AF undergoing catheter ablation (n = 217) and (ii) a control group (n = 105). (i) Adipokines, oxidative stress, indirect autonomic markers, and leucocytes mRNA levels were analysed; (ii) correlation between biomarkers was explored with heatmaps and Kendall correlation coefficients; and (iii) logistic regression and random forest model were used to determine predictors of AF recurrence after ablation. Our results showed that: (i) fatty acid-binding protein 4 (FABP4) and leptin levels were higher in women than in men in both cohorts (P < 0.01). In women, FABP4 levels were higher on AF cohort (20 ± 14 control, 29 ± 18 paroxysmal AF and 31 ± 17 ng/mL persistent AF; P < 0.01). In men, leptin levels were lower on AF cohort (22 ± 15 control, 13 ± 16 paroxysmal AF and 13 ± 11 ng/mL persistent AF; P < 0.01). (ii) In female with paroxysmal AF, there was a lower acetylcholinesterase and higher carbonic anhydrase levels with respect to men (P < 0.05). (iii) Adipokines have an important role on discriminate AF recurrence after ablation. In persistent AF, FABP4 was the best predictor of recurrence after ablation (1.067, 95% confidence interval 1-1.14; P = 0.046). Conclusion: The major finding of the present study is the sex-based differences of FABP4 and leptin levels according to AF burden. These adipokines are associated with oxidative stress, inflammatory and autonomic indirect markers, indicating that they may play a role in AF perpetuation.This study was supported by projects (PI16/01282 and PI18/01584) integrated in the Plan Estatal de I+D+I 2016–2019 and cofounded by ISCIII-Subdirección General de Evaluación y Fomento de la Investigación del Fondo Europeo de Desarrollo Regional (FEDER). J.N.L.-C. and M.R.-M. were a recipient of a Sociedade Galega de Cardioloxía (SOGACAR) research grant. D.d.G.-C. was a recipient of a Juan de la Cierva-Incorporación grant from the Ministry of Science Innovation and Universities (IJCI-2016-29393). CIBER Cardiovascular (CB16/11/00403 to V.Ll.-C. and D.d.G.-C.) is a project from Carlos III Health Institute.Peer reviewe

    Comparative study on the valorization of Sargassum from the Mexican Caribbean coast and Gulf of California as an ingredient on healthy diets for shrimp farming

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    Funding: This work received the financial support of the project GCRFNGR4/1388 "Algae bloom: waste resource for aquaculture and bioenergy industry in Mexico".Sargassum biomass is a potential ingredient for aquaculture formulations due to its high nutritional value and availability, as it contains a variety of essential nutrients including proteins, carbohydrates, lipids, vitamins, antioxidants, fiber, and minerals, which are essential for aquatic growing, development and health parameters including digestibility and immune response against diseases. Therefore, in this work, five experimental diets were formulated considering 2.5 % and 5 % levels of inclusion of Sargassum spp. from the Mexican Caribbean coasts (SC), and from the Gulf of California (SG), and one reference diet as a control. The characterization of the raw material and the proximal analysis of the five diets were evaluated according to standard reference methods. A 35-day feeding trial was conducted using juvenile Litopenaeus vannamei showed a shrimp survival rate of 97 ± 6 % (p > 0.05) on SC. Excellent weight gain (WG) performance of SC and SG diets at 2.5 % of inclusion resulted in >10 % WG compared to the control. The specific activity of amylase, lipase, trypsin, and chymotrypsin showed a significant increase by including Sargassum in diets, compared with the reference diet. Incorporating Sargassum at 2.5 % in feed formulations for shrimps showed a great opportunity to use it as an ingredient and improved production yields. The digestion and absorption parameters were represented by the enzymatic activity in which the diets based on Sargassum spp. from the Mexican Caribbean coast (SC) have resulted in the best performance.Publisher PDFPeer reviewe

    Agricultural waste as a sustainable source for nanoparticle synthesis and their antimicrobial properties for food preservation

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    Traditional agriculture from cropping to harvesting is contributing to climate change by increasing global greenhouse emissions. Circular economy approaches and biorefinery technologies based on the reuse, recycling, and remanufacturing might result in the valorization of wastes that consequently would avoid environmental pollution. Nanoparticles synthesis using bio-waste such as stems, leaves, seeds, pulp, stubble, and bagasse is considered a green approach with low energy consumption, and low-cost production. Characteristics of raw materials influence the final application of nanoparticles in edible coatings, and films. Therefore, the preparation of nanoparticles based on cellulose, pectin, metal (titanium oxide, silver, zinc oxide), or silica are considered organic, inorganic, or hybrid nanocomposites, are resulted in several benefits including shelf-life extension and broad-spectrum antimicrobial properties by its capacity to encapsulate active compounds that greatly improve food preservation. For considering agro-waste-based nanoparticles in food, challenges in homogenization and synthesis, yield, and toxicity are mainly described. Therefore, this review examines the employment of agro-industrial waste for the development of sustainable nanoparticles and their synthesis methods (top-down and bottom-up). Moreover, it discusses their incorporation and role in active edible coatings and films by highlighting their bioactive properties, mechanisms of action, and applications in food group preservation

    Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria

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    The speciation of dissolved iron (DFe) in the ocean is widely assumed to consist almost exclusively of Fe(III)-ligand complexes. Yet in most aqueous environments a poorly defined fraction of DFe also exists as Fe(II), the speciation of which is uncertain. Here we deploy flow injection analysis to measure in situ Fe(II) concentrations during a series of mesocosm/microcosm/multistressor experiments in coastal environments in addition to the decay rate of this Fe(II) when moved into the dark. During five mesocosm/microcosm/multistressor experiments in Svalbard and Patagonia, where dissolved (0.2 µm) Fe and Fe(II) were quantified simultaneously, Fe(II) constituted 24 %–65 % of DFe, suggesting that Fe(II) was a large fraction of the DFe pool. When this Fe(II) was allowed to decay in the dark, the vast majority of measured oxidation rate constants were less than calculated constants derived from ambient temperature, salinity, pH, and dissolved O2. The oxidation rates of Fe(II) spikes added to Atlantic seawater more closely matched calculated rate constants. The difference between observed and theoretical decay rates in Svalbard and Patagonia was most pronounced at Fe(II) concentrations <2 nM, suggesting that the effect may have arisen from organic Fe(II) ligands. This apparent enhancement of Fe(II) stability under post-bloom conditions and the existence of such a high fraction of DFe as Fe(II) challenge the assumption that DFe speciation in coastal seawater is dominated by ligand bound-Fe(III) species
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