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Search Results: 1 - 10 of 463005 matches for " Frederico A.;Giron "
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Laparoscopic diagnosis and treatment of nonpalpable testis
Denes, Francisco T.;Saito, Fernando J.;Silva, Frederico A.;Giron, Amilcar M.;Machado, Marcos;Srougi, Miguel;
International braz j urol , 2008, DOI: 10.1590/S1677-55382008000300010
Abstract: introduction: treatment of the cryptorchid testicle is justified due to the increased risk of infertility and malignancy as well as the risk of testicular trauma and psychological stigma on patients and their parents. approximately 20% of cryptorchid testicles are nonpalpable. in these cases, the videolaparoscopic technique is a useful alternative method for diagnosis and treatment. materials and methods: we present data concerning 90 patients submitted to diagnostic laparoscopy for impalpable testicles. forty-six patients (51.1%) had intra-abdominal gonads. in 25 testicles of 19 patients, we performed a two stage laparoscopic fowler-stephens orchiopexy. the other 27 patients underwent primary laparoscopic orchiopexy, in a total of 29 testicles. results: we obtained an overall 88% success rate with the 2 stage fowler-stephens approach and only 33% rate success using one stage fowler-stephens surgery with primary vascular ligature. there was no intraoperative complication in our group of patients. in the laparoscopic procedures, the cosmetic aspect is remarkably more favorable as compared to open surgeries. hospital stay and convalescence were brief. conclusions: in pediatric age group, the laparoscopic approach is safe and feasible. furthermore, the laparoscopic orchiopexy presents excellent results in terms of diagnosis and therapy of the impalpable testis, which is why this technique has been routinely incorporated in our department.
Laparoscopic renal surgery in infants and children: is it a feasible and safe procedure for all pediatric age groups?
Denes, Francisco T.;Tavares, Alessandro;Monteiro, Edison D. S.;Bessa Jr., Jose de;Giron, Amilcar M.;Queiroz Filho, Frederico A.;Srougi, Miguel;
International braz j urol , 2008, DOI: 10.1590/S1677-55382008000600009
Abstract: purpose: although laparoscopy is considered the mainstay for most renal procedures in adults, its role in the pediatric population is still controversial, especially for smaller children. we reviewed our experience in pediatric renal laparoscopic surgery in three pediatric age groups in an attempt to identify if age has an impact on feasibility and surgical outcomes. materials and methods: from november 1995 to may 2006, 144 pediatric laparoscopic renal procedures were performed at our institution. the charts of these patients were reviewed for demographic data, urologic pathology and surgical procedure, as well as perioperative complications and post-operative outcomes. the findings were stratified into 3 groups, according to patient age (a: < 1 year, b: 1 to 5 years and c: 6-18 years). results: median age of the patients was 4.2 years (42 days - 18 years). we performed 54 nephrectomies, 33 nephroureterectomies, 19 upper pole nephrectomies, 11 radical nephrectomies, 22 pyeloplasties and 4 miscellaneous procedures. the 3 age groups were comparable in terms of the procedures performed. conversion rates were 0%, 1.4% and 1.9% for groups a, b and c, respectively (p = 0.72). incidence of perioperative complications was 5%, 8.2% and 7.8% for age groups a to c, respectively (p = 0.88). conclusions: most renal procedures can be performed safely by laparoscopy in the pediatric population, with excellent aesthetic and functional outcomes. the morbidity related to the procedure was minimal irrespective of the age group.
Why Are So Many Bird Flowers Red?
Miguel A. Rodríguez-Gironés,Luis Santamaría
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0020350
Abstract:
Linkage Rules for Plant–Pollinator Networks: Trait Complementarity or Exploitation Barriers?
Luis Santamaría,Miguel A. Rodríguez-Gironés
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0050031
Abstract: Recent attempts to examine the biological processes responsible for the general characteristics of mutualistic networks focus on two types of explanations: nonmatching biological attributes of species that prevent the occurrence of certain interactions (“forbidden links”), arising from trait complementarity in mutualist networks (as compared to barriers to exploitation in antagonistic ones), and random interactions among individuals that are proportional to their abundances in the observed community (“neutrality hypothesis”). We explored the consequences that simple linkage rules based on the first two hypotheses (complementarity of traits versus barriers to exploitation) had on the topology of plant–pollination networks. Independent of the linkage rules used, the inclusion of a small set of traits (two to four) sufficed to account for the complex topological patterns observed in real-world networks. Optimal performance was achieved by a “mixed model” that combined rules that link plants and pollinators whose trait ranges overlap (“complementarity models”) and rules that link pollinators to flowers whose traits are below a pollinator-specific barrier value (“barrier models”). Deterrence of floral parasites (barrier model) is therefore at least as important as increasing pollination efficiency (complementarity model) in the evolutionary shaping of plant–pollinator networks.
Influencia de la temperatura en las propiedades a tracción de un acero inoxidable superdúplex
Gironès, A.,Mateo, A.,Lianes, L.,Anglada, M.
Revista de Metalurgia , 2001,
Abstract: Tensile tests, at temperatures ranging between 275 and 475 °C were performed in a superduplex stainless steel EN 1.4410. The dependence of yield stress and ultimate tensile strength on temperature indicates the existence of dynamic strain aging (DSA). In order to evaluate the influence of strain rate on this phenomenon, tests were conducted at two different strain rates, both at 325 °C, temperature at which DSA is maximum for this material. The results show that the flow stress has an inverse strain rate sensitivity which confirms the existence of DSA in the steel under study. Un acero inoxidable superduplex tipo EN 1.4410 se ensayó a tracción en el rango de temperaturas de 275 a 475 °C. La evolución, en función de la temperatura, de los valores de límite elástico y resistencia máxima indica la existencia de un fenómeno de envejecimiento por deformación (Dynamic Strain Aging, DSA). Para evaluar la influencia de la velocidad de deformación sobre dicho comportamiento se realizaron ensayos de tracción a dos velocidades diferentes, ambos a la temperatura de 325 °C, para la cual se había registrado la máxima manifestación de DSA. Dichos ensayos reflejaron una sensibilidad inversa a la velocidad de deformación lo que confirma la presencia de DSA en el acero bifásico estudiado.
Why Are So Many Bird Flowers Red?
Miguel A Rodríguez-Gironés ,Luis Santamaría
PLOS Biology , 2004, DOI: 10.1371/journal.pbio.0020350
Abstract:
Linkage Rules for Plant–Pollinator Networks: Trait Complementarity or Exploitation Barriers?
Luis Santamaría ,Miguel A Rodríguez-Gironés
PLOS Biology , 2007, DOI: 10.1371/journal.pbio.0050031
Abstract: Recent attempts to examine the biological processes responsible for the general characteristics of mutualistic networks focus on two types of explanations: nonmatching biological attributes of species that prevent the occurrence of certain interactions (“forbidden links”), arising from trait complementarity in mutualist networks (as compared to barriers to exploitation in antagonistic ones), and random interactions among individuals that are proportional to their abundances in the observed community (“neutrality hypothesis”). We explored the consequences that simple linkage rules based on the first two hypotheses (complementarity of traits versus barriers to exploitation) had on the topology of plant–pollination networks. Independent of the linkage rules used, the inclusion of a small set of traits (two to four) sufficed to account for the complex topological patterns observed in real-world networks. Optimal performance was achieved by a “mixed model” that combined rules that link plants and pollinators whose trait ranges overlap (“complementarity models”) and rules that link pollinators to flowers whose traits are below a pollinator-specific barrier value (“barrier models”). Deterrence of floral parasites (barrier model) is therefore at least as important as increasing pollination efficiency (complementarity model) in the evolutionary shaping of plant–pollinator networks.
Resource Competition Triggers the Co-Evolution of Long Tongues and Deep Corolla Tubes
Miguel A. Rodríguez-Gironés, Ana L. Llandres
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002992
Abstract: Background It is normally thought that deep corolla tubes evolve when a plant's successful reproduction is contingent on having a corolla tube longer than the tongue of the flower's pollinators, and that pollinators evolve ever-longer tongues because individuals with longer tongues can obtain more nectar from flowers. A recent model shows that, in the presence of pollinators with long and short tongues that experience resource competition, coexisting plant species can diverge in corolla-tube depth, because this increases the proportion of pollen grains that lands on co-specific flowers. Methodology/Principal Findings We have extended the model to study whether resource competition can trigger the co-evolution of tongue length and corolla-tube depth. Starting with two plant and two pollinator species, all of them having the same distribution of tongue length or corolla-tube depth, we show that variability in corolla-tube depth leads to divergence in tongue length, provided that increasing tongue length is not equally costly for both species. Once the two pollinator species differ in tongue length, divergence in corolla-tube depth between the two plant species ensues. Conclusions/Significance Co-evolution between tongue length and corolla-tube depth is a robust outcome of the model, obtained for a wide range of parameter values, but it requires that tongue elongation is substantially easier for one pollinator species than for the other, that pollinators follow a near-optimal foraging strategy, that pollinators experience competition for resources and that plants experience pollination limitation.
Spider Movement, UV Reflectance and Size, but Not Spider Crypsis, Affect the Response of Honeybees to Australian Crab Spiders
Ana L. Llandres,Miguel A. Rodríguez-Gironés
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017136
Abstract: According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees.
The Nuclear Sigma Term in the Skyrme Model: Pion-Nucleus Interaction
A. Gammal,T. Frederico
Physics , 1998, DOI: 10.1103/PhysRevC.57.2830
Abstract: The nuclear sigma term is calculated including the nuclear matrix element of the derivative of the NN interaction with respect to the quark mass, $m_q\frac{\partial V_{NN}}{\partial m_q}$. The NN potential is evaluated in the skyrmion-skyrmion picture within the quantized product ansatz. The contribution of the NN potential to the nuclear sigma term provides repulsion to the pion-nucleus interaction. The strength of the s-wave pion-nucleus optical potential is estimated including such contribution. The results are consistent with the analysis of the experimental data.
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