3,586 research outputs found

    O Papel das Prostaglandinas na Dinâmica do Tracto Urinário Inferior de Doentes Prostatectomizados: um Ensaio com Indometacina e Aspirina

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    Using 49 prostatectomized patients as experimental subjects, we studied the effects of Inclometnacin and acetylsalicylic acid — accredited prostaglandin synthetase inhibitors — from a urodynamic and clinical standpoint. Relevant urodynamic data was gathered 1 hr 30 mi after the patients had taken the drugs and placebo. Clinical results were further scrutinized after 8 days of treatment, at which time a new urodynamic workup was again performed on some patients. Results were again studied shortly after the end of treatment. The effect of the drugs on bladder and urethral structures was borne out by clear-ct!t clinical and urodynamic changes. After statistically analyzing such changes, we concluded that prostaglandin synthesis inhibition resulting in the inhibition of prostaglandin action had, at least in part, led to the changes noted. In the present report we shall discuss the role played by the highly complex mechanisms at work

    A brainstem-like modulation approach for gait transition in a quadruped robot

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    The ability to traverse a wide variety of terrains while walking is basically a requirement for performing useful tasks in our human centric world. In this article, we propose a bio-inspired robotic controller able to generate locomotion and to easily switch between different type of gaits. In order to improve the robot stability and response while locomoting, we adjust both the duty factor and the interlimb phase relationships, according to the velocities. We extend previous work, by applying nonlinear oscillators to generate the rhythmic locomotor movements for a quadruped robot, similarly to the biological counterparts. The generated trajectories are modulated by a drive signal, that modifies the oscillator frequency, amplitude and the coupling parameters among the oscillators, proportionally to the drive signal strength. By increasing the drive signal, locomotion can be elicited and velocity increased while switching to the appropriate gaits. This drive signal can be specified according to sensory information or set a priori. The implementation of the central pattern generator network and the activity modulation layer is shown in simulation and in an AIBO robot

    Informació negativa en copiar l'elecció de parella

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    Triar parella és una de les decisions més importants per a qualsevol organisme viu, especialment per a les femelles, per a les quals els costos reproductius són generalment més elevats. Per tant, s'espera que aquesta selecció sexual actuarà sobre el comportament de les femelles a l'hora d'escollir parella, afavorint els comportaments que són capaços de prendre les millors decisions. Els models clàssics de l'evolució de l'elecció femenina de parella assumeixen que les seves preferències són genèticament innates. Això vol dir que les femelles amb un, per exemple, al·lel que les faci tenir una "preferència pel verd" preferiran aparellar-se amb mascles que presentin ornaments d'aquest color, i que aquesta preferència no canviarà al llarg de la vida de les femelles, amb independència de l'actuació dels mascles amb ornaments verds. Són les preferències de les femelles exclusivament genètiques i, per tant, immutables? L'evidència empírica suggereix que no és així.Elegir pareja es una de las decisiones más importantes para cualquier organismo vivo, especialmente para las hembras, para las cuales los costes reproductivos son generalmente más elevados. Por lo tanto, se espera que esta selección sexual actuará sobre el comportamiento de las hembras a la hora de escoger pareja, favoreciendo los comportamientos que son capaces de tomar las mejores decisiones. Los modelos clásicos de la evolución de la elección femenina de pareja asumen que sus preferencias son genéticamente innatas. Esto quiere decir que las hembras con un, por ejemplo, alelo que las haga tener una "preferencia por el verde" preferirán aparearse con machos que presenten ornamentos de ese color, y que esta preferencia no cambiará a lo largo de la vida de las hembras, con independencia de la actuación de los machos con ornamentos verdes. ¿Son las preferencias de las hembras exclusivamente genéticas y, por tanto, inmutables? La evidencia empírica sugiere que no es así.Choosing whom to mate with is one of the most important decisions for any living organism, especially for females, for whom the costs of reproduction are generally higher. It is, therefore, expected that sexual selection will act on female mate choice behaviour, favouring the ones capable of making the better decisions. The classical models of female mate choice evolution assume that their preferences are genetically innate. This means that females with an (e.g.) allele for "green preference" would prefer mating with males displaying green ornaments, and that this preference will never change throughout females' lives, independently of the performance of green males. Are females' preference exclusively genetic and, therefore, immutable? Empirical evidence suggests it is not

    No evidence for short‐term evolutionary response to a warming environment in Drosophila

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    Adaptive evolution is key in mediating responses to global warming and may sometimes be the only solution for species to survive.Such evolution will expectedly lead to changes in the populations’ thermal reaction norm and improve their ability to cope with stressful conditions. Conversely, evolutionary constraints might limit the adaptive response. Here, we test these expectations by performing a real-time evolution experiment in historically differentiated Drosophila subobscura populations. We address the phenotypic change after nine generations of evolution in a daily fluctuating environment with average constant temperature, or in a warming environment with increasing average and amplitude temperature across generations. Our results showed that (1) evolution under a global warming scenario does not lead to a noticeable change in the thermal response; (2) historical background appears to be affecting responses under the warming environment, particularly at higher temperatures; and (3) thermal reaction norms are trait dependent: although lifelong exposure to low temperature decreases fecundity and productivity but not viability,high temperature causes negative transgenerational effects on productivity and viability, even with high fecundity. These findings in such an emblematic organism for thermal adaptation studies raise concerns about the short-term effciency of adaptive responses to the current rising temperatures.info:eu-repo/semantics/acceptedVersio

    Anti-MuSK-positive myasthenia gravis diagnosed during pregnancy: New challenges for an old disease

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    Myasthenia gravis is an autoimmune disorder affecting predominantly women in their reproductive age. The course of the disease during pregnancy is unpredictable, although it is more difficult to manage earlier in the gestation. Myasthenia gravis with antibodies against the muscle-specific receptor tyrosine kinase (anti-MuSK) has been described as a subtype of disease with more localised clinical features and a poorer response to treatment than acetylcholine receptor antibody (anti-AChR)-positive patients. Few cases have been reported in pregnant women, with deliveries being performed mainly by caesarean section. We report a successful case of vaginal delivery and describe our experience providing the first review of the management of this subtype of disease during pregnancy

    High developmental temperature leads to low reproduction despite adult temperature

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    Phenotypic plasticity can help organisms cope with changing thermal conditions and it may depend on which life-stage the thermal stress is imposed: for instance, exposure to stressful temperatures during development can trigger a positive plastic response in adults. Here, we analyze the thermal plastic response of laboratory populations of Drosophila subobscura, derived from two contrasting latitudes of the European cline. We measured reproductive performance through fecundity characters, after the experimental populations were exposed to five thermal treatments, with different combinations of developmental and adult temperatures (14°C, 18°C, or 26°C). Our questions were whether (1) adult performance is changed with exposure to higher (or lower) temperatures during development; (2) flies raised at lower temperatures outperform those developed at higher ones, supporting the “colder is better” hypothesis; (3) there is a cumulative effect on adult performance of exposing both juveniles and adults to higher (or lower) temperatures; (4) there is evidence for biogeographical effects on adult performance. Our main findings were that (1) higher developmental temperatures led to low reproductive performance regardless of adult temperature, while at lower temperatures reduced performance only occurred when colder conditions were persistent across juvenile and adult stages; (2) flies raised at lower temperatures did not always outperform those developed at other temperatures; (3) there were no harmful cumulative effects after exposing both juveniles and adults to higher temperatures; (4) both latitudinal populations showed similar thermal plasticity patterns. The negative effect of high developmental temperature on reproductive performance, regardless of adult temperature, highlights the developmental stage as very critical and most vulnerable to climate change and associated heat waves.info:eu-repo/semantics/publishedVersio

    Beneficial developmental acclimation in reproductive performance under cold but not heat stress

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    Thermal plasticity can help organisms coping with climate change. In this study, we analyse how laboratory populations of the ectotherm species Drosophila subobscura, originally from two distinct latitudes and evolving for several generations in a stable thermal environment (18 °C), respond plastically to new thermal challenges. We measured adult performance (fecundity traits as a fitness proxy) of the experimental populations when exposed to five thermal regimes, three with the same temperature during development and adulthood (15-15 °C, 18-18 °C, 25-25 °C), and two where flies developed at 18 °C and were exposed, during adulthood, to either 15 °C or 25 °C. Here, we test whether (1) flies undergo stress at the two more extreme temperatures; (2) development at a given temperature enhances adult performance at such temperature (i.e. acclimation), and (3) populations with different biogeographical history show plasticity differences. Our findings show (1) an optimal performance at 18 °C only if flies were subjected to the same temperature as juveniles and adults; (2) the occurrence of developmental acclimation at lower temperatures; (3) detrimental effects of higher developmental temperature on adult performance; and (4) a minor impact of historical background on thermal response. Our study indicates that thermal plasticity during development may have a limited role in helping adults cope with warmer - though not colder - temperatures, with a potential negative impact on population persistence under climate change. It also emphasizes the importance of analysing the impact of temperature on all stages of the life cycle to better characterize the thermal limits.info:eu-repo/semantics/publishedVersio

    A new CPG model for the generation of modular trajectories for hexapod robots

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    Legged robots are often used in a large variety of tasks, in different environments. Nevertheless, due to the large number of degrees-of-freedom to be controlled, online generation of trajectories in these robots is very complex. In this paper, we consider a modular approach to online generation of trajectories, based on biological concepts, namely Central Pattern Generators (CPGs). We introduce a new CPG model for hexapod robots’ rhythms, based in the work of Golubitsky et al (1998). Each neuron/oscillator in the CPG consists of two modules/primitives: rhythmic and discrete. We study the effect on the robots’ gaits of superimposing the two motor primitives, considering two distinct types of coupling.We conclude, from the simulation results, that the amplitude and frequency of periodic solutions, identified with hexapods’ tripod and metachronal gaits, remain constant for the two couplings, after insertion of the discrete part.CP was supported by Research funded by the European Regional Development Fund through the programme COMPETE and by the Portuguese Government through the FCT Fundacao para a Ciencia e a Tecnologia under the project PEst-C/MAT/UI0144/2011. This work was also funded by FEDER Funding supported by the Operational Program Competitive Factors COMPETE and National Funding supported by the FCT - Portuguese Science Foundation through project PTDC/EEACRO/100655/2008

    3β-Acet­oxy-lup-20(29)-en-28-yl 1H-1,2,4-tri­azole-1-carboxyl­ate

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    The title triterpene, C35H53N3O4, is a C-28 carbamate derivative of 3β-acet­oxy­betulin prepared in a one-step reaction from the commercially available 1,1′-carbonyl-di(1,2,4-triazole) (CDT), crystallized from acetone/n-hexane. All rings are trans fused. The carbamate and acetate substituents are in axial and equatorial positions, respectively. A quantum chemical ab initio Roothaan Hartree–Fock calculation of the equilibrium geometry of the isolated mol­ecule gives values for bond lengths and valency angles in close agreement with experimental values. The calculation also reproduces the observed mol­ecular conformation, with puckering parameters that agree well with those determined from the crystallographic study
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