1,146 research outputs found
Oligomers, organosulfates, and nitrooxy organosulfates in rainwater identified by ultra-high resolution electrospray ionization FT-ICR mass spectrometry
Wet deposition is an important removal mechanism for atmospheric organic matter, and a potentially important input for receiving ecosystems, yet less than 50% of rainwater organic matter is considered chemically characterized. Precipitation samples collected in New Jersey, USA, were analyzed by negative ion ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Elemental compositions of 552 unique molecular species were determined in the mass range 50–500 Da in the rainwater. Four main groups of organic compounds were identified: compounds containing carbon, hydrogen, and oxygen (CHO) only, sulfur (S) containing CHOS compounds, nitrogen (N) containing CHON compounds, and S- and N- containing CHONS compounds. Organic acids commonly identified in precipitation were detected in the rainwater. Within the four main groups of compounds detected in the rainwater, oligomers, organosulfates, and nitrooxy-organosulfates were assigned based on elemental formula comparisons. The majority of the compounds identified are products of atmospheric reactions and are known contributors to secondary organic aerosol (SOA) formed from gas phase, aerosol phase, and in-cloud reactions in the atmosphere. It is suggested that the large uncharacterized component of SOA is the main contributor to the large uncharacterized component of rainwater organic matter
Mechanisms leading to oligomers and SOA through aqueous photooxidation: insights from OH radical oxidation of acetic acid and methylglyoxal
Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including pyruvate, oxalate and oligomers. These products are found predominantly in the particle phase in the atmosphere, suggesting that methylglyoxal is a precursor of secondary organic aerosol (SOA). Acetic acid plays a central role in the aqueous oxidation of methylglyoxal and it is a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor in its own right. However, the fate of acetic acid upon aqueous-phase oxidation is not well understood. In this research, acetic acid (20 μM–10 mM) was oxidized by OH radicals, and pyruvic acid and methylglyoxal experimental samples were analyzed using new analytical methods, in order to better understand the formation of SOA from acetic acid and methylglyoxal. Glyoxylic, glycolic, and oxalic acids formed from acetic acid and OH radicals. In contrast to the aqueous OH radical oxidation of methylglyoxal, the aqueous OH radical oxidation of acetic acid did not produce succinic acid and oligomers. This suggests that the methylgloxal-derived oligomers do not form through the acid catalyzed esterification pathway proposed previously. Using results from these experiments, radical mechanisms responsible for oligomer formation from methylglyoxal oxidation in clouds and wet aerosols are proposed. The importance of acetic acid/acetate as an SOA precursor is also discussed. We hypothesize that this and similar chemistry is central to the daytime formation of oligomers in wet aerosols
Plyometric Training in Female Volleyball Players. Systematic Review
El voleibol femenino se práctica en todo el mundo a nivel profesional y amateur. Los saltos verticales son una parte fundamental para el desarrollo de este deporte, por lo que el entrenamiento pliométrico puede ser eficaz para un aumento del rendimiento. El propósito de estudio fue describir cuáles han sido los métodos y programas de entrenamiento pliométrico en mujeres que practican voleibol, así como el resultado obtenido en función de estos. El proceso de búsqueda en las bases de datos se llevó a cabo desde Marzo hasta Junio de 2016. Las bases de datos consultadas fueron Pubmed, Web of Science, Cochrane y SPORTDiscus. La revisión sistemática fue realizada bajo las recomendaciones de la declaración PRISMA. La calidad metodológica de los estudios fue evaluada mediante la Escala PEDro. Como resultado, se obtuvieron un total de 205 artículos tras eliminar aquellos que estaban por duplicado. Finalmente 7 artículos fueron seleccionados. Los resultados principales fueron que aquellos estudios que utilizan deportistas amateurs obtienen mejores resultados que los realizados con deportistas profesionales cuando se realizan programas de entrenamiento pliométrico. También se indica que un período de entrenamiento pliométrico de baja intensidad puede prevenir una disminución en la altura del salto vertical; así como es necesario programar la pretemporada para evitar pérdida en la capacidad de salto. Todo ello parece indicar, como conclusión, que es necesario una disminución del volumen y un aumento de la intensidad en el entrenamiento pliométrico.Female volleyball is practiced all over the world at a professional and amateur level. Vertical jumps are a fundamental part of the development of this sport. In this sense, plyometric training can be effective for increased performance. The purpose of the study was to describe the methods and programs of plyometric training in women volleyball players, as well as the results obtained from them. The following electronic databases were searched March to June 2016. Electronic databases consulted were Pubmed, Web of Science, Cochrane and SPORTDiscus. This systematic review was performed following PRISMA statement. PEDro scale was used to evaluated the methodological quality of the included studies. As total of 205 articles were obtained after remove duplicates. Finally 7 articles were selected. The main results were that those studies using amateur athletes obtain better results than those performed with professional athletes when performing plyometric training programs. It is also indicated that a period of low intensity plyometric training could prevent a decrease in vertical jump height; As well as it is necessary to schedule the preseason to avoid loss in the ability to jump. All this seems to indicate, in conclusion, that a decrease in volume and an increase in intensity in the training of plyometric training is necessary
Contribution of the d-Serine-Dependent Pathway to the Cellular Mechanisms Underlying Cognitive Aging
An association between age-related memory impairments and changes in functional plasticity in the aging brain has been under intense study within the last decade. In this article, we show that an impaired activation of the strychnine-insensitive glycine site of N-methyl-d-aspartate receptors (NMDA-R) by its agonist d-serine contributes to deficits of synaptic plasticity in the hippocampus of memory-impaired aged rats. Supplementation with exogenous d-serine prevents the age-related deficits of isolated NMDA-R-dependent synaptic potentials as well as those of theta-burst-induced long-term potentiation and synaptic depotentiation. Endogenous levels of d-serine are reduced in the hippocampus with aging, that correlates with a weaker expression of serine racemase synthesizing the amino acid. On the contrary, the affinity of d-serine binding to NMDA-R is not affected by aging. These results point to a critical role for the d-serine-dependent pathway in the functional alterations of the brain underlying memory impairment and provide key information in the search for new therapeutic strategies for the treatment of memory deficits in the elderly
Relationship between anthropometric parameters, physiological responses, routes and competition results in formula windsurfing
Formula windsurfing is faster than the Olympic version, due to anumber of unique differences. This study was designed to identify the importance of anthropometric and cardiac factors on the final result of the European Formula Windsurf Championships (2007). We selected 45 competitors (30 amateurs and 15 professionals) of 30±9.77 years of age, a height of 182.6±0.06 cm, a weight of 81.67±7.35 kg and a BMIof 24.7±2.1 kg. They were divided into three groups (PG: 15; TG: 45and GPSG: 12). We followed the recommendations of Carter and Marfell-Jones for the anthropometric measurements. The route, speed, distance and heart rate were recorded using an FRWD W600 GPS (Global Positioning System) unit. The anthropometric measurements indicate a professional profile with 2.3±0.4 endomorphy 5±0.8 mesomorphy and 2.4±0.6 ectomorphy. Arm span and fat mass show a significant (p≤0.02) and very significant (p≤0.005) correlation with the final classification. The average speed was 11.84±2.38 km·h–1, the heart rate varied from 128 to 180 b·min–1 and the average was 127.62±13.73 b·min–1. The distances covered (12784.77±5522.19 m) and the times used for the races (2049.3±989.68 s) were very variable. This will assist not only in initial selection for the sport, but also in the design of training programmes which further develop that morphology, where possible, in the pursuit of improved performance
Mothers of Soldiers in Wartime: A National News Narrative
National news media represent mothers of US combat soldiers in the Iraq War as archetypal good mothers, that is, mothers who continue their maternal work even after their children are deployed. However, not all mothers are depicted as the archetypal patriotic mother, i.e., a good mother who is also stoic and silent about the war and her child\u27s role in it. Mothers of soldiers are portrayed as good mothers who sometimes also voice their attitudes about the war effort. The maternal attitudes ranged from complete support for the war to opposition to the war but support for the soldiers. The findings suggest a picture of wartime motherhood that is more nuanced than the historical image of the patriotic mother suggests
Exploring the Cross-Species Experience and the Coevolutionary Capacity: Sensorial Transcoding and Critical Play Design of Bio-Sonic Sense
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