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Background In malaria endemic regions, transmission of Plasmodium falciparum parasites is often seasonal with very low transmission during the dry season and high transmission in the wet season. Parasites survive the dry season within some individuals who experience prolonged carriage of parasites and are thought to ‘seed’ infection in the next transmission season. Methods Dry season carriers and their role in the subsequent transmission season are characterized using a combination of mathematical simulations and data analysis of previously described data from a longitudinal study in Mali of individuals aged 3 months–12 years (n = 579). Results Simulating the life-history of individuals experiencing repeated exposure to infection predicts that dry season carriage is more likely in the oldest, most exposed and most immune individuals. This hypothesis is supported by the data from Mali, which shows that carriers are significantly older, experience a higher biting rate at the beginning of the transmission season and develop clinical malaria later than non-carriers. Further, since the most exposed individuals in a community are most likely to be dry season carriers, this is predicted to enable a more than twofold faster spread of parasites into the mosquito population at the start of the subsequent wet season. Conclusions Carriage of malaria parasites over the months-long dry season in Mali is most likely in the older, more exposed and more immune children. These children may act as super-spreaders facilitating the fast spread of parasites at the beginning of the next transmission season.

Dominance hierarchies confer benefits to group members by decreasing the incidences of physical conflict, but may result in certain lower ranked individuals consistently missing out on access to resources. Here, we report a linear dominance hierarchy remaining stable over time in a closed population of birds. We show that this stability can be disrupted, however, by the artificial mass loading of birds that typically comprise the bottom 50% of the hierarchy. Mass loading causes these low-ranked birds to immediately become more aggressive and rise-up the dominance hierarchy; however, this effect was only evident in males and was absent in females. Removal of the artificial mass causes the hierarchy to return to its previous structure. This interruption of a stable hierarchy implies a strong direct link between body mass and social behaviour and suggests that an individual's personality can be altered by the artificial manipulation of body mass.

OBJETIVO: Determinar el pronostico del tratamiento medico y quirúrgico de pacientes con pancreatitis aguda necrótica. INTRODUCCIÓN: El tratamiento de pancreatitis aguda severa es multidisciplinario y requiere la evaluación de los pacientes día a día, esto permite observar los cambios y dar terapia oportuna. El tratamiento incluye: admisión en UCI, fluidos, nutrición y antibióticos, así como otros soportes de vida para paciente critico. Con esto, los pacientes pueden ser tratados conservadoramente o si fuese necesario; con intervención quirúrgica. MÉTODOS: Un estudio retrospectivo de pacientes con pancreatitis aguda necrótica, que ingresaron a la Unidad de Cuidados Intensivos, entre enero del 2004 a agosto del 2006. Los pacientes con pancreatitis aguda necrótica sin signos de sepsis fueron sometidos a tratamiento medico conservador. Se realizó una punción aspiración con aguja fina, a partir de la cuarta semana, a los pacientes con pancreatitis aguda necrótica y sepsis persistente. Previamente se descartó y erradicó todos los focos infecciosos no pancreáticos. Todos los pacientes con coloración Gram. ó cultivo positivo fueron sometidos a cirugía de inmediato. RESULTADOS: Setenta pacientes con pancreatitis aguda necrótica fueron incluidos, de los cuales 36 (51%) tuvieron pancreatitis aguda necrótica estéril con tratamiento medico conservador y 34 (49%) tuvieron pancreatitis aguda necrótica infectada con tratamiento quirúrgico. El promedio de edad fue 55.19 vs. 57.65 (p=0.57). El promedio de amilasas 1421.74 vs. 1402.45. (p=0.96). El índice de severidad tomográfica fue 8.47 vs. 8.79 (p=0.36). Apache II fue 8.22 vs. 9 (p=0.46). El promedio de órganos fallados 0.39 vs. 0.68. (p=0.19). La estancia en UCI fue de 10.75 vs. 26.5 días (p

One conspicuous feature of several larger bird species is their annual migration in V-shaped or echelon formation. When birds are flying in these formations, energy savings can be achieved by using the aerodynamic up-wash produced by the preceding bird. As the leading bird in a formation cannot profit from this up-wash, a social dilemma arises around the question of who is going to fly in front? To investigate how this dilemma is solved, we studied the flight behavior of a flock of juvenile Northern bald ibis (Geronticus eremita) during a human-guided autumn migration. We could show that the amount of time a bird is leading a formation is strongly correlated with the time it can itself profit from flying in the wake of another bird. On the dyadic level, birds match the time they spend in the wake of each other by frequent pairwise switches of the leading position. Taken together, these results suggest that bald ibis cooperate by directly taking turns in leading a formation. On the proximate level, we propose that it is mainly the high number of iterations and the immediacy of reciprocation opportunities that favor direct reciprocation. Finally, we found evidence that the animals' propensity to reciprocate in leading has a substantial influence on the size and cohesion of the flight formations.

Many species travel in highly organized groups. The most quoted function of these configurations is to reduce energy expenditure and enhance locomotor performance of individuals in the assemblage. The distinctive V formation of bird flocks has long intrigued researchers and continues to attract both scientific and popular attention. The well-held belief is that such aggregations give an energetic benefit for those birds that are flying behind and to one side of another bird through using the regions of upwash generated by the wings of the preceding bird4,7,9,10,11, although a definitive account of the aerodynamic implications of these formations has remained elusive. Here we show that individuals of northern bald ibises (Geronticus eremita) flying in a V flock position themselves in aerodynamically optimum positions, in that they agree with theoretical aerodynamic predictions. Furthermore, we demonstrate that birds show wingtip path coherence when flying in V positions, flapping spatially in phase and thus enabling upwash capture to be maximized throughout the entire flap cycle. In contrast, when birds fly immediately behind another bird—in a streamwise position—there is no wingtip path coherence; the wing-beats are in spatial anti-phase. This could potentially reduce the adverse effects of downwash for the following bird. These aerodynamic accomplishments were previously not thought possible for birds because of the complex flight dynamics and sensory feedback that would be required to perform such a feat. We conclude that the intricate mechanisms involved in V formation flight indicate awareness of the spatial wake structures of nearby flock-mates, and remarkable ability either to sense or predict it. We suggest that birds in V formation have phasing strategies to cope with the dynamic wakes produced by flapping wings.

To determine the prognosis of patients with necrotic acute pancreatitis receiving medical and surgical treatments.The severe acute pancreatitis treatment is multidisciplinary and requires a daily evaluation of the patient that will allow to observe changes and apply therapy in due time. The treatment includes: Admission in the ICU, fluids, nutrition and antibiotics, as well as other life supports for high-risk patients. Thus, patients undergo conservative treatment or, if it is necessary, surgery.A retrospective study of patients with necrotic acute pancreatitis admitted to the ICU between January 2004 and August 2006. The patients with necrotic acute pancreatitis without signs of sepsis underwent a conservative medical treatment, while fine needle punction-aspiration was performed in all patients who were suffering from necrotic acute pancreatitis and persistent sepsis four weeks after their admission and after discarding and eradicating every non-pancreatic focus of infection. All Gram stain or culture positive patients underwent surgery immediately.Seventy patients with necrotic acute pancreatitis were included in the study. Thirty-six patients (51%) suffered acute pancreatitis with sterile necrosis and underwent a conservative treatment, while 34 patients (49%) developed acute pancreatic with infected necrosis and underwent surgery. The average age was 55.19 vs. 57.65 (p=0.57). The average amylase was 1421.74 vs. 1402.45. (p=0.96). The tomography severity index was 8.47 vs. 8.79 (p=0.36). The Apache II was 8.22 vs. 9 (p=0.46). The average number of failed organs was 0.39 vs. 0.68. (p=0.19). The ICU stay was 10.75 vs. 26.5 days (p0.05) while the total hospital stay was 46.47 vs. 57.26 days (p0.05). The mortality rate was (3/36) 8.3% vs. (9/34) 26.5% (p0.05) for conservative medical treatment vs. surgical treatment, respectively. Between the first and the twelfth month the evaluated patients who attended consultation, after discharge, showed: pancreatic pseudocyst 9/36 (25%) vs. 8/34(23.5%); recurring abdominal pain 3/36 (8.3%) vs. 4/34 (11.8%); and relapsing acute pancreatitis 3/36 (8.3%) vs. 2/34 (5.8%); while 4/36 (11.1%) vs. 3/34 (8.8%) did not show any problem. There were not significant differences between the conservative and the surgical medical treatment, respectively.Patients suffering acute pancreatitis with sterile necrosis can undergo conservative medical treatment which will result in a lower mortality rate, while the hospital stay, in comparison with acute pancreatitis with infected necrosis, will not be affected.

Introducción: La Incontinencia Urinaria de Esfuerzo (IUE) se maneja quirúrgicamente diferente siguiendo la Teoría Integral de la Continencia razón por la cual es importante el conocimiento de las estructuras anatómicas. Desarrollamos un modelo tridimensional basado en la anatomía de la pelvis para el entrenamiento manual de la cirugía y así disminuir la curva de aprendizaje de urólogos y ginecólogos. Objetivo: Demostrar en modelos sintéticos, las bases anatómicas del manejo transobturatriz en la IUE, cistoceles y en IUE recidivante post tratamiento quirúrgico. Metodología: El modelo anatómico incluye: huesos pélvicos, las principales capas de los músculos pélvicos, ligamentos y fascias. Los dispositivos quirúrgicos son agujas transobturatrizes en forma de "C" y helicoidales; un sling reajustable de acceso universal y una malla especial autofijable y el sling crossover. Fue realizado un entrenamiento con clases teóricas y prácticas. Las clases prácticas fueron realizadas con las pelvis y los dispositivos de la cirugía transobturatriz. A continuación fueran realizadas cirugías transobturatrizes en ovejas. Al final, se aplicó un cuestionario para verificar el impacto de esta herramienta en la curva de aprendizaje del acceso transobturatriz. Resultados: Con respecto al concepto anatómico, el 90% (n=72) de los participantes, clasificó el modelo como muy bueno y 10% (n=8) como bueno. Como herramienta para el aprendizaje de los procedimientos transobturatrizes, el 100% aprobó tanto el material escrito como el modelo anatómico tridimensional. Conclusiones: Este modelo sintético permite entender y poner en práctica las diversas técnicas quirúrgicas, substituyendo los modelos animales, las reconstrucciones tridimensionales computarizadas y las imágenes bidimensionales, contribuyendo así de forma significativa en la curva de aprendizaje. Introduction: Stress Urinary Incontinence (SUI) may be managed by transobturator approach. We developed a threedimensional model, for understanding the surgical anatomy and manual training as well, in order to reduce the learning curve for pelvic surgeries. Objective: To demonstrate in synthetic models, the anatomical basis for the management of SUI and cystocele. Method: The anatomical model includes: pelvic bones, the main layers of the pelvic muscles, ligaments and fascias. The surgical devices were transobturator needles, synthetic slings and meshes for anterior vaginal wall repair. The workshop was carried out with an anatomical overview and hands-on training in this tridimentional models and finally surgery in animals. At the end, a questionnaire was applied to verify the impact of this tool in the learning process and trainee satisfaction. Results: As far as the anatomical concept, 90% (n=72) of the participants classified this model as very good and 10% (n=8) as good. As a tool for understanding the tridimentional pelvic floor anatomy applied to transobturator procedures there were 100% of approval. Conclusions: This synthetic model allows for understanding the pelvic floor tridimentional anatomy and surgical procedures as well. Further skill is got in the animal model reducing the learning curve for transobturator procedures.

Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (GH2O) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell GH2O and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in GH2O has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between GH2O and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher GH2O than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher GH2O than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the GH2O are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher GH2O to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher GH2O to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours.