Experimental model for the description of the behaviour of a 9-mm projectile at a target.

Analysis of crime scenes involving single-fire-gun projectiles requires the determination of the direction of arrival of a projectile at the target and other factors to reconstruct events. The movement of a projectile can be analyzed by applying Euler's equations to a solid symmetrical rigid body. The present work starts from a Newtonian reformulation of these equations to show that, in the presence of a gravitational field, the system can be expressed with a complex variable nonlinear equation, where the inclusion of small nutation variables allows us to find possible solutions. As a particular case, we analyzed the movement of a 9-mm projectile fired from distances greater than 1 m to demonstrate that the direction of arrival of the projectile at the target cannot be traced by a stick placed in the target hole, as is usually performed in crime investigations. A series of shots were fired from distances varying between 1 m and 7 m. Impact data were recorded on Riemann planes of projection for the description of nutation and precession motions, allowing the observation of the motion dynamics of the projectile. We show that the direction of arrival at the target can be determined approximately from the analysis of the nutation and precession curves through Riemann planes of projection. The results presented in this work will allow more accurate judgements to be made in judicial investigations.

Las escuelas críticas: entre la socialización política y los procesos de subjetivación / Critical schools: between political socialization and subjectivization processes / Escolas críticas: entre a socialização política e os processos de subjetivação

Este artículo analiza prácticas escolares de socialización política fundamentadas en pedagogías críticas, derivadas en procesos de formación de subjetividades en jóvenes, aquí denominadas procesos de subjetivación. Es una investigación cualitativa desarrollada en cuatro instituciones educativas de Medellín, Colombia. Su objetivo es analizar experiencias inspiradas en pedagogías críticas (“Escuelas Críticas”), en sus posibilidades y límites de configurar procesos de subjetivación, para propiciar el encuentro de los sujetos consigo mismos y con otros, creándose líneas de fuga a la matriz escolar moderna. Estas experiencias formativas se configuran a partir de transacciones entre elementos de matrices pedagógicas críticas, liberales y pastorales. La investigación aplica el método de análisis estructural de contenido (Hiernaux), tanto a textos de autores de pedagogías críticas (Freire, Giroux), como a testimonios de educadores y fuentes documentales.

This article presents the qualitative research conducted in four educational institutions in Medellin, Colombia. Its aim is to examine the educational practices of political socialization based on critical pedagogies (Critical Schools). These practices generate the formation of subjectivities in young people, here called subjectivization processes. The study aims to understand the possibilities and the limits of these processes in promoting encounters of the subjects with themselves and with others, creating alternative paths (lignes de fuite) within the modern school model. These formative experiences are configured through transactions between elements from critical, liberal or pastoral models of teaching. The research uses a method of structural content analysis (Hiernaux) along with texts by classic thinkers from critical pedagogies (Freire, Giroux) and testimonies from educators and other documentary sources.

Este artigo analisa as práticas escolares de socialização política fundamentadas em pedagogias críticas, que geram processos de formação de subjetividades nos jovens, aqui referidos como processos de subjetivação. É uma pesquisa qualitativa desenvolvida em quatro instituições de ensino de Medellín (Colômbia), cujo objetivo é analisar experiências inspiradas em pedagogias críticas (“escolas críticas”). Procura-se entender as possibilidades e os limites dos processos de subjetivação para promover o encontro dos sujeitos com eles mesmos e com outros, criando caminhos alternativos ao modelo escolar moderno. Estas experiências formativas configuram-se a partir de transações entre elementos de matrizes pedagógicas críticas, liberais e pastorais. A pesquisa aplica o método de análise estrutural de conteúdo (Hiernaux), tanto em textos de autores de pedagogias críticas (Freire, Giroux), quanto a depoimentos de educadores e a fontes documentais.

Incidence of the boundary condition between bone and soft tissue in a finite element model of a transfemoral amputee.

BACKGROUND: Many finite element investigations have been made in the field of lower limb prosthetics; however, friction between bone and soft tissues as a boundary condition has not been considered. OBJECTIVES: To establish whether the change in the contact boundary condition between bone and soft tissues in a transfemoral amputee affects the stress-strain state on the residual limb. STUDY DESIGN: Finite element analysis comparison. METHODS: Finite element models of four transfemoral amputees were developed. In these models the socket, soft tissues and femur were included and two simulations were made for each model, in one of them the interaction between bone and soft tissues was defined as tied (there is no relative displacement between surfaces) and in the other it was defined as a friction boundary condition. RESULTS: The von Mises stress and strain peaks are higher when the friction definition is used than for tied contact definition. The distribution pattern of stresses and strains also change when the contact definition varies from tied to friction. CONCLUSIONS: It was concluded that the friction between bone and soft tissues have a significant impact on the results of finite element models of lower limb prosthetic systems, and therefore in its predictive capabilities. Clinical relevance Understanding the bone-soft tissue interaction can lead to more realistic and accurate finite element models used to predict the stress-strain state in the residual limb of prosthetic users and therefore predict the occurrence of deep tissue injuries.

Analysis of bone demineralization due to the use of exoprosthesis by comparing Young's modulus of the femur in unilateral transfemoral amputees.

BACKGROUND: There is a relation between Hounsfield units obtained from computed tomography (CT) scans and bone density. The density of the bones can be used to establish its mechanical properties and therefore to assess the bone mechanical condition using CT images. OBJECTIVES: To identify the effect of the transfemoral amputation and the use of external lower limb prosthesis in the bone properties, by comparing Young's modulus. STUDY DESIGN: Young's modulus comparison. METHODS: Comparison of bone density between the healthy femur and the amputated bone of 20 unilateral transfemoral amputees was done by generating three histograms of the Hounsfield units at different parts of the femur. The histograms were created based on images obtained by CT and the Hounsfield units were translated to Young's modulus to establish the comparison. RESULTS: The results show a significant difference (p-value <0.05) between the mean value of Young's modulus of healthy and amputated bone. CONCLUSIONS: There is clearly a direct association between the use of external prosthesis and the bone demineralization due the stress shielding phenomenon. The Young's modulus comparison using information from CT images can be a suitable tool to analyze the bone demineralization due to the use of exoprosthesis.

Jóvenes y VIH/SIDA: enfoques y perspectivas en investigación / Young people and the HIV/AIDS: research approaches and perspectives

Este escrito realiza un acercamiento a las investigaciones sobre el Virus de Inmunodeficiencia Adquirido (VIH) y del Síndrome de Inmunodeficiencia Adquirida (SIDA) de los jóvenes, como problema social. Analiza los principales temas, enfoques metodológicos y respuestas, perfilando sus límites y posibilidades para reconocer las tensiones y los conflictos que viven estos jóvenes en la sociedad actual. Resalta la escasa producción investigativa a partir de la experiencia de los jóvenes que viven con el VIH/SIDA y propone pensar en un nuevo proyecto de investigación que respalde una forma de conocer y de responder a este complejo fenómeno, con una mirada integradora que genere nuevos sentidos, para comprender y desarrollar nuevas formas de acción (AU)

This article aims at approaching the different studies on Human Immunodeficiency Virus (HIV) and Acquired Immunodeficiency Syndrome (AIDS) from a perspective as a social issue. By examining the main topics, methodological approaches and actions, this study intends to outline limits as well as possibilities in order to identify the most common tensions and conflicts these young people usually go through at present. It is also a call to think of a new research project that could support new ways of approaching and finding solutions for this complex phenomenon since there is too little research production on how young people live and cope with HIV/AIDS (AU)

Initial clinical experience with a sac-anchoring endoprosthesis for aortic aneurysm repair.

OBJECTIVE: All current aortic endografts depend on proximal and distal fixation to prevent migration. However, migration and rupture can occur, particularly in patients with aortic necks that are short or angulated, or both. We present our initial clinical experience with a new sac-anchoring endoprosthesis designed to anchor and seal the device within the aneurysm sac. METHODS: The initial worldwide experience using a new endoprosthesis for the treatment of aortic aneurysms (Nellix Endovascular, Palo Alto, Calif) was reviewed. The endoprosthesis consists of dual balloon-expandable endoframes surrounded by polymer-filled endobags designed to obliterate the aneurysm sac and maintain endograft position. Clinical results and follow-up contrast computed tomography (CT) scans at 30 days and 6 and 12 months were reviewed. RESULTS: The endograft was successfully deployed in 21 patients with infrarenal aortic aneurysms measuring 5.7 ± 0.7 cm (range, 4.3-7.4 cm). Two patients with common iliac aneurysms were treated with sac-anchoring extenders that maintained patency of the internal iliac artery. Infusion of 71 ± 37 mL of polymer (range, 19-158 mL) into the aortic endobags resulted in complete aneurysm exclusion in all patients. Mean implant time was 76 ± 35 minutes, with 33 ± 17 minutes of fluoroscopy time and 180 ± 81 mL of contrast; estimated blood loss was 174 ± 116 mL. One patient died during the postoperative period (30-day mortality, 4.8%), and one died at 10 months from non-device-related causes. During a mean follow-up of 8.7 ± 3.1 months and a median of 6.3 months, there were no late aneurysm- or device-related adverse events and no secondary procedures. CT imaging studies at 6 months and 1 year revealed no increase in aneurysm size, no device migration, and no new endoleaks. One patient had a limited proximal type I endoleak at 30 days that resolved at 60 days and remained sealed. One patient has an ongoing distal type I endoleak near the iliac bifurcation, with no change in aneurysm size at 12 months. CONCLUSION: Initial clinical experience with this novel intrasac anchoring prosthesis is promising, with successful aneurysm exclusion and good short-term results. This new device platform has the potential to address the anatomic restrictions and limitations of current endografts. Further studies with a longer follow-up time are needed.

Plan Hospital Eugenio Espejo para desastres / Plan Hospital Eugene Mirror for disasters

El presente trabajo de investigación está dividido en dos componentes: el primer componente hace referencia a la elaboración del Plan Hospitalario para Desastres del Hospital Eugenio Espejo, y el segundo componente consiste en la realización de un Seminario-Taller sobre desastres. Componente I: Elaboración del Plan Hospitalario para Desastres Internos y Externos. Se realizó una evaluación de la vulnerabilidad estructural y no estructural del Hospital lo que le permitió tomar las medidas de prevención y mitigación necesarias. Se evaluó el actual funcionamiento de los servicios básicos con los que cuenta el Hospital (agua potable, luz eléctrica, alcantarillado, comunicaciones) y se tomó los correctivos necesarios; igualmente se estableció formas alternas de funcionamiento que suelen ser esenciales ante las situaciones críticas que suelen presentarse en situaciones de desastres...

Recuperación de cromo de licores residuales; práctica industrial de una curtiembre de pieles vacunas que procesa 100 Tn/día

Analiza las distintas posibilidades de reciclado de curtido y exprimido, optándose por la vía de precipitación con hidróxido de cromo, filtración, lavado y redisolución. Finalmente, mediante la oxidación con bicromato de sodio en medio acido, se eliminan masivamente los vestigios de materia orgánica presente. Este licor se utiliza como materia prima para la fabricación de sulfato básico de cromo (33 grados Sch) en una planta de reducción con SO2. Describe la planta e incluye diagrama de flujo. Señala que el nivel de pureza y composición del producto final obtenido (sulfato básico de cromo) lo hace apto para ser utilizado como material curtiente y recurtiente, sin modificar las características de calidad del curtido

Recuperación de cromo de licores residuales; práctica industrial de una curtiembre de pieles vacunas que procesa 100 Tn/día

Analiza las distintas posibilidades de reciclado de curtido y exprimido, optándose por la vía de precipitación con hidróxido de cromo, filtración, lavado y redisolución. Finalmente, mediante la oxidación con bicromato de sodio en medio acido, se eliminan masivamente los vestigios de materia orgánica presente. Este licor se utiliza como materia prima para la fabricación de sulfato básico de cromo (33 grados Sch) en una planta de reducción con SO2. Describe la planta e incluye diagrama de flujo. Señala que el nivel de pureza y composición del producto final obtenido (sulfato básico de cromo) lo hace apto para ser utilizado como material curtiente y recurtiente, sin modificar las características de calidad del curtido