Nondestructive Prediction of the Buckling Load of Imperfect Shells.

From soda cans to space rockets, thin-walled cylindrical shells are abundant, offering exceptional load carrying capacity at relatively low weight. However, the actual load at which any shell buckles and collapses is very sensitive to imperceptible defects and cannot be predicted, which challenges the of such structures. Consequently, probabilistic descriptions in terms of empirical design rules are used and designing reliable structures requires the use of conservative strength estimates. We introduce a nonlinear description where finite-amplitude perturbations trigger buckling. Drawing from the analogy between imperfect shells which buckle and imperfect pipe flow which becomes turbulent, we experimentally show that lateral probing of cylindrical shells reveals their strength nondestructively. A new ridge-tracking method is applied to commercial cylinders with a hole showing that when the location where buckling nucleates is known we can accurately predict the buckling load of each individual shell, within ±5%. Our study provides a new promising framework to understand shell buckling, and more generally, imperfection-sensitive instabilities.

Estudio etnográfico de jóvenes skater: prácticas corporales y urbanas / Ethnographic study of young skaters: body and urban practices

El presente trabajo corresponde a un estudio etnográfico clásico, que tiene como objetivo explorar el espacio de construcción de los nuevos estilos de vida y prácticas corporales en los jóvenes skaters urbanos de Colima. El estudio se realizó en un parque emblemático: La Piedra Lisa, localizado en la capital del estado de Colima, México. La unidad de observación la integraron 50 jóvenes, entre 12 y 20 años, que practican el skate durante la semana. El método utilizado fue el etnográfico, las técnicas de investigación fueron la observación participante ­durante un mes y medio­ y la entrevista informal; y como instrumento de registro se empleó el diario de campo. En la sistematización de la información y clasificación se usó la Guía de Murdock. El estudio describe aspectos identitarios de los jóvenes skaters, información acerca del desarrollo de habilidades físicas coordinativas, condicionales y de experticia skate, lugares de encuentro y apropiación de espacios públicos, clasificación de los skaters por grupos, el equipamiento utilizado, y la percepción social que se tiene de sí mismos, de la sociedad, la familia y de los amigos.

The present work corresponds to a classic ethnographic study, which aims to explore the construction space of new lifestyles and bodily practices in young urban skaters in Colima. The study was conducted in an emblematic park: La Piedra Lisa, located in the capital of the state of Colima, Mexico. The observation unit was made up of 50 young people between 12 and 20 years old, who skate during the week. The method used was ethnographic, the research techniques were participant observations ­for a month and a half­ and the informal interview, and the field newspaper was used as recording instrument. For the systematization of information and classification, the Murdock Guide was used. The study describes identity aspects of young skaters, information about the development of coordinative, conditional and skateboarding physical skills, meeting places and appropriation of public spaces, classification of skaters by groups, the equipment used, and the social perception that it has of itself, society, family and friends.

Fuentes, síntomas y estrategias de afrontamiento al estrés-competitivo en nadadores / Fontes, sintomas e estratégias de confronto de estresse competitivo em nadadores / Sources, symptoms and coping strategies in stress - competitive in swimmers

La presente investigación de tipo descriptivo transversal tuvo como objetivo caracterizar el estrés-precompetitivo de 123 nadadores mexicanos de categoría master. La edad de los participantes osciló entre los 36 y 92 años de edad. El instrumento utilizado para recoger la información fue el cuestionario FUSIES (fuentes, síntomas y estrategias de afrontamiento al estrés), este se aplicó antes de iniciar una competencia nacional perteneciente al serial master de natación. El instrumento midió la percepción del estrés, bajo una escala tipo Likert de 1= nunca y 5 = extremo, con alfa de Cronbach de .95. Entre los principales resultados se observó un nivel normal-bajo de estrés (M = 2.307 ± .5) en los nadadores; las fuentes que generan mayor estrés son la injusticia de autoridades (M = 3.70 ± 1.2), mucho tráfico (M = 3.48 ± 1.1) y no tener dinero (M = 3.28 ± 1.2). A su vez, los síntomas de estrés con mayor puntaje en los nadadores es la preocupación (M = 2.96 ± 1.08), la tensión en la espalda (M = 2.62 ± 1.2) y el tartamudeo (M = 2.34 ± 1.3). En lo relativo a las estrategias de afrontamiento que aplican con mayor frecuencia los nadadores son: ejercitarse (M = 3.59 ± 1.35), buscar la solución del problema (M = 3.51 ± 1.35) y pensar positivamente (M = 3.51 ± 1.31). Concluyendo que el pensar positivamente, les permite reducir sus niveles de preocupación, inseguridad y desesperación pre competitiva, por lo que se asume que los niveles de estrés percibidos se encuentran en un nivel moderado (AU)

This transversal descriptive research aimed to characterize the stress-precompetitive 123 swimmer’s category Mexican master. The age of participants ranged between 36 and 92 years old. The instrument used to collect information was the questionnaire FUSIES (sources, symptoms and stress coping strategies), this was applied before starting a master serial belonging to national swimming competition. The instrument measures perceived stress, under a Likert scale from 1 = never and 5 = extreme, with Cronbach's alpha of .95. Among the main results normal-low stress (M = 2,307 ± 0.5) was observed in swimmers; sources that generate greater stress are the injustice of authorities (M = 3.70 ± 1.2), a lot of traffic (M = 3.48 ± 1.1) and no money (M= 3.28 ± 1.2). In turn, symptoms of stress with the highest score in swimmers is Concern (M= 2.96 ± 1.08), the back strain (M= 2.62 ± 1.2) and stuttering (M= 2.34 ± 1.3). Regarding coping strategies most frequently applied swimmers are: exercise (M= 3.59 ± 1.35), finding the solution (M = 3.51 ± 1.35) and think positively (M = 3.51 ± 1.31). Think positively concluding that allows them to reduce their levels of concern, insecurity and desperation pre-competitive, so it is assumed that levels of perceived stress are at a moderate level (AU)

Esta pesquisa descritiva transversal objetivou caracterizar a 123 nadadores o estresse pré-competitiva na natação master mexicana. A idade dos participantes variou entre 36 e 92 anos de idade. O instrumento utilizado para coleta de informações foi o FUSIES (fontes, sintomas e estratégias de confronto do estresse), este foi aplicado antes de iniciar um serial master da competição nacional de natação. O instrumento mediu o estresse percebido com a escala de Likert de 1 = nunca e 5 = sempre, com alfa de Cronbach 0,95. Entre os principais resultados o nível normail-baixo de estresse (M = 2,307 ± 0,5) foi observada nos nadadores; fontes que geram uma maior estresse são a injustiça das autoridades (M = 3,70 ± 1,2), tráfego (M = 3,48 ± 1,1) e não ter dinheiro (M = 3,28 ± 1,2). Por sua vez, sintomas de estresse com o maior número de pontos em nadadores é a preocupação (M = 2,96 ± 1,08), a tensão nas costas (M = 2,62 ± 1,2) e tartamudez (M = 2,34 ± 1,3). No que diz respeito as estratégias de confronto mais frequentemente aplicada pelos nadadores são fazer exercício (M = 3,59 ± 1,35), procurar a solução do problema (M = 3,51 ± 1,35) e pensamento positivo (M = 3,51 ± 1,31). Concluindo que o pensamento positivo, permite-lhes reduzir os seus níveis de preocupação, insegurança e desespero pré competitivo, por isso, assumese que os níveis de estresse percebido estão em um nível moderado (AU)

A perianal presentation of myeloid sarcoma.

Myeloid sarcoma is a rare tumour associated with acute myeloid leucaemia (AML). Infrequently, it can occur in myelodysplastic/myeloproliferative overlap syndrome conditions such as chronic monomyelocytic leucaemia (CMML), where it often heralds the transformation towards an AML. We discuss a rare presentation of myeloid sarcoma in the perianal region of a 51-year-old man, who was seen by various clinicians and treated for haemorrhoids and perianal abscess. There were no gross abnormalities in initial haematological investigations and the patient was systemically well. A histological biopsy demonstrated myeloid sarcoma and bone marrow aspirate, and trephine confirmed CMML transforming to AML. Treatment of myeloid sarcoma is dependent on whether there is associated AML in the bone marrow. Dual chemotherapy with cytarabine and daunorubicin remains the gold standard treatment in these patients. Sending histology samples of atypical lesions when performing incision and drainage procedures is extremely important, as it contributes to early detection of rare and malignant tissue diagnoses.

Relationships between repeated sprint ability, mechanical parameters, and blood metabolites in professional soccer players.

This study analyzed the acute metabolic and mechanical responses to a specific repeated sprint ability (RSA) test. Eighteen male professional soccer players from a team of the First Division of Spanish National League participated. A 12 × 30-m RSA test with 30-second recovery together with countermovement jump test (CMJ) pre a post RSA test was performed. Mechanical responses (i.e., height performance in CMJ and speed loss) and metabolic responses (i.e., blood lactate and ammonia concentrations) were measured before and after exercise. A related sample t-test was used to analyze CMJ height pre-post changes as well as to compare pre- and post-exercise lactate and ammonia levels. Countermovement jump height loss pre-post session (8%) was significant, and fatigue, measured as CMJ height loss, was strongly correlated to lactate (r = 0.97; p < 0.001) and ammonia (r = 0.92; p < 0.001) for all players. The relationships between the variables studied were determined by calculating the Pearson correlation coefficients. The metabolic stress developed during the effort can be estimated by controlling CMJ because of the high correlation between CMJ and blood lactate and ammonia concentrations. The high correlations found between mechanical (speed and CMJ height losses) and metabolic (lactate and ammonia) measures of fatigue highlight the utility and validity of using CMJ to monitor training load and quantify objectively neuromuscular fatigue during RSA.

Maximal ATPase activity and calcium sensitivity of reconstituted myofilaments are unaltered by the fetal troponin T re-expressed during human heart failure.

Re-expression of a fetal isoform of troponin T (TnT(4)) has been demonstrated in failing human ventricular myocardium and associated with a decrease in myofibrillar ATPase activity. In order to elucidate the regulatory role of the re-expressed TnT(4) in the failing human heart, we measured ATPase activity in reconstituted cardiac myofilaments prepared with recombinant human TnT(4) or the adult human isoform of troponin T (TnT(3)). Neither the maximal calcium-activated ATPase activity nor the calcium sensitivity of this biochemical assay was significantly different between reconstituted myofilaments containing adult TnT(3) or fetal TnT(4). Our results suggest that the re-expressed fetal TnT(4) is not responsible for the depressed ATPase activity of failing ventricular myofibrils. The increased expression of the fetal isoform of this thin filament regulatory protein in the failing ventricle may be a consequence of a programmed change in gene expression occurring in response to hemodynamic stress, but probably does not contribute to depressed ventricular function characteristic of dilated cardiomyopathies.

Endometriosis extrapélvica de localización inguinal: reporte de un caso / Extrapelvic endometriosis of inguinal localization: report of a case

La endometriosis es un diagnóstico ginecológico muy común. Esta interesante enfermedad puede observarse virtualmente en cualquier órgano y sistema del organismo, planteando dificultades para el diagnóstico y tratamiento. Se describe un raro caso de endometriosis extrapélvica de localización inguinal, con el objeto de enfatizar la importancia de incluir a esta enfermedad dentro de los diagnósticos diferenciales en la práctica quirúrgica general

Mionecrosis retroperitoneal post-traumática / Retroperitoneal myonecrosis post-traumatic

La fractura pélvica, es una lesión que se observa con frecuencia en el paciente politraumatizado. Entre las complicaciones de las fracturas pélvicas que revisten mayor gravedad se encuentran la hemorragia y la sepsis, esta última se presenta asociada a lesión de viscera hueca intrapélvica. Se ha descrito el compromiso de vejiga y utero como los órganos más frecuentemente afectados, seguidos por recto y uréter. La lesión de otros órganos perineales asociada a fractura de pelvis es sumamente rara. En este estudio se discute un singular caso de lesión alta de vagina como consecuencia de una fractura pélvica compuesta con infección necrotizante del espacio retroperitoneal, que se supone tomó esta vía puerta de entrada. La debridación quirúrgica mediante laparotomías seriadas y la antibioticoterapia empírica con cobertura contar gérmenes anaerobios y gram negativos, fueron las bases del tratamiento, concordando con las pautas actualmente aceptadas, las cuales se traen a discusión

Endometriosis extrapélvica de localización inguinal: reporte de un caso / Extrapelvic endometriosis of inguinal localization: report of a case

Reporte de un caso infrecuente de endometriosis extrapélvica y revisión bibliográfica del conocimiento actual sobre el tema. Resumen del caso clínico y búsqueda bibliográfica empleando bases de datos médicos en internet. Servicio de Cirugía II, Hospital Vargas de Caracas. Se describe un raro caso de endometriosis extrapélvica de localización inguinal, con el objeto de recalcar la importancia de incluir a esta enfermedad dentro de los diagnósticos diferenciales en la práctica quirúrgica general. La endometriosis es un diagnóstico ginecológico común. La enfermedad puede estar localizada en cualquier órgano y sistema del organismo planteando dificultades en el diagnóstico y tratamiento. La endometriosis en la región inguinal es poco frecuente, fue descrita por primera vez en 1986 y desde entonces sólo 24 casos han sido reportados. Según el consenso actual el tratamiento para la endometriosis extrapélvica de localización inguinal es quirúrgico. Si de forma simultánea el paciente presenta endometriosis intrapélvica, el tratamiento con terapia supresora puede estar indicado