2,036 research outputs found
Functional relevance of the newly evolved sperm dynein intermediate chain multigene family in Drosophila melanogaster males.
In many animal species, traits associated with male fitness evolve rapidly. Intersexual conflict and male-male competition have been suggested to drive this rapid evolution. These fast evolutionary dynamics result in elevated rates of amino acid replacement and modification of gene expression attributes. Gene acquisition is another mechanism that might contribute to fitness differences among males. However, empirical evidence of fitness effects associated with newly evolved genes is scarce. The Sdic multigene family originated within the last 5.4 myr in the lineage that leads to D. melanogaster and encodes a sperm dynein intermediate chain presumably involved in sperm motility. The silencing of the Sdic multigene family, followed by the screening of relevant phenotypes, supports the role of the Sdic multigene family in sperm competition. The case of the Sdic multigene family illustrates the flexibility of genetic networks in incorporating lineage-specific gene novelties that can trigger an evolutionary arms race between males
Comparative analysis of low nitrogen emissions fertilizers based on activated carbon from residual materials
Nitrate leaching and ammonia volatilization are the main pathways of nitrogen loss in agriculture. New environmentally friendly fertilizers have been investigated in recent years in order to reduce nitrogen losses and associated impacts [1]. One suggested solution has been to incorporate biochar as soil amendment, since its effects on nitrogen retention and soil fertility are well known [2, 3]. Fertilizer production from activated biocarbon is the researched line explored in this work. Biochar has been produced from two different raw materials, residual biomass and coal mine residues. Both have been produced through a physical activation process in an externally heated quartz tubular reactor [4]. After an experimental period, the optimized conditions were reached and the biochar product was obtained showing good microporosity and adsorption characteristics. The final product was used to set up the new fertilizer, and its nitrogen retention capacity was experimentally tested by laboratory and pot trials.
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Nouvelle manga, mon amour : reflexiones sobre la narración gráfica de historias cotidianas
Desde sus primeras manifestaciones hace más de un siglo, el cómic se ha ido consolidando como un género popular sobretodo dirigido a un lector juvenil. Su evidente atractivo entre los lectores ha hecho que algunos padres, educadores y profesionales del ámbito de la promoción de la lectura se plantearan el por qué de dicha afición, llegando a conclusiones erróneas como la creencia de que se trata de una lectura menor, dirigida esencialmente a la pura distracción de quien los lee. El manga, en concreto, es el género dentro del cómic que más se consume en occidente. Se ha convertido en un fructífero producto de mercado que deriva en videojuegos, series de televisión, películas de cine… Su gran acogida entre el público infantil y juvenil preocupa a mediadores por la supuesta carga violenta y sexual y la baja calidad literaria de sus obras. El presente propuesta tratará de deshacer algunos tópicos en relación con la concepción errónea la historieta nipona, a partir del estudio de un corpus de obras creadas por autores japoneses y europeos que quieren aportar un cómic de calidad tanto en su forma como en el contenido, abriendo así las puertas a nuevas investigaciones de gran interés. La Novelle manga es un nuevo género dentro del cómic nipón que aúna las estrategias comunicativas más destacables de las novelas gráficas japonesas, el valor estético del cómic francés y la sencillez y el tono de las películas de cine francés dentro de la Nouvelle Vague para crear un cómic que narra historias cotidianas de gran valor literario y estético, muy recomendable para lectores juveniles y adultos
Pellet heat transfer coefficients in packed beds: global and local values
Pellet heat transfer coefficients in a packed bed have been obtained, both for specific individual pellets and for the entire bed. They are referred to as local and global values, respectively. It appears that the local values are scattered around the global value. This is due to the heat transfer coefficient of individual pellets being statistically distributed, as a result of the randomnes of the packing. At low Reynolds numbers, both global and local values fall well below Nu = 2, which is the lower limit for a single sphere in absence of convection. In the literature, this behaviour has been attributed i.a. to axial dispersion and fluid maldistribution. However, these phenomena cannot explain why the same behaviour is observed in slurries. The fact that the local values fall below Nu = 2 would suggest that neither of these explanations is valid for packed beds
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Mobility in individuals with traumatic lower-limb injuries : implications for device design, surgical intervention and rehabilitation therapies
Traumatic injuries to the extremities are commonly observed in emergency room patients and military personnel in combat. Restoring high mobility and functionality is a primary goal post-injury, which may require the use of rehabilitative devices, surgical interventions, and rehabilitation therapies. The research detailed in this dissertation investigates specific elements of these approaches through the use of experimental study and modeling and simulation. In the first study, the influence of passive-dynamic ankle-foot orthosis bending axis on the gait performance of limb salvage subjects was investigated. Bending axis location was altered by fabricating customized orthosis components using additive manufacturing and was tested in a gait laboratory. Altering bending axis location did not result in large or consistent changes in gait measures, however subjects expressed strong preferences for bending axis condition and preference was strongly related to specific gait measures. This suggests that preference and comfort are important factors guiding the prescription of bending axis location. In the second study, musculoskeletal modeling was used to examine the influence of transfemoral amputation surgical techniques on muscle capacity to generate forces and moments about the hip. Muscle reattachment tension and stabilization were shown to be critical parameters for post-amputation capacity, which supports the use of myodesis stabilization (muscle is reattached directly to bone) in amputation procedures. In the third study, a forward dynamics simulation of transfemoral amputee gait was developed and used to examine individual muscle and prosthesis contributions to walking subtasks. The residual hip muscles, and intact ankle, knee, and hip muscles worked synergistically to provide body support, anteroposterior propulsion, mediolateral control, and leg swing. Increased contributions of contralateral muscles to ipsilateral subtasks as well as increased duration of specific muscle contributions were observed in comparison to non-amputee and transtibial amputee walking. These findings can be used to help develop targeted rehabilitation therapies and improve transfemoral amputee locomotion. Through elucidating the influence of PD-AFO bending axis on gait performance as well as the influence of transfemoral amputation surgical techniques on muscle capacity and function, this research provides a foundation for improved rehabilitation outcomes, and thus mobility for individuals who have experienced traumatic lower-limb injuries.Mechanical Engineerin
System identification of a hydraulically-actuated robot
A feedback control system has been developed to operate an elastic robot arm. This work was funded by a grant from the U.S. Army Research Office. The goal of this investigation was to experimentally determine the operating curves, performance plots, and flow coefficients needed to produce an appropriate servovalve signal when operating the hydraulically-actuated robot arm. Through the assimilation of data collected in the laboratory the parameters were determined
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