163 research outputs found
Estudio biomecánico del proceso de consolidación de fracturas con sistemas de fijación externa rígidos y elásticos
El objetivo básico de este trabajo es discernir las diferencias existentes
entre los sistemas de fijación externa rígidos y elásticos aplicados al
tratamiento de fracturas óseas. El abordaje de este problema se ha
cubierto en varias etapas, la primera de ellas ha consistido en el diseño de
un fijador externo que permitiera un comportamiento rígido y con posibilidad
de transformación en elástico, utilizable en tibias de conejo adulto.
A continuación se ha realizado un estudio teórico de dicho fijador mediante
el método de los elementos finitos (MEF) y, finalmente, un estudio en
animales de experimentación en tres campos: biomecánico, morfológico y
monitorización "in vivo" del callo de fractura.
El estudio teórico realizado en ambos sistemas de fijación ha mostrado
que, con independencia del método de inmovilización utilizado (rígido o
elástico), las cargas soportadas por el callo de fractura dependen básicamente
de las características elásticas de este elemento.
Los ensayos de rotura a tracción practicados en los distintos especímenes
no han mostrado diferencias estadísticamente significativas según el
método de fijación utilizado. De igual forma las imágenes histológicas de
los distintos callos dependen exclusivamente del tiempo de consolidación
transcurrido y no del sistema de fijación empleado.
Los resultados teóricos están refrendados por la monitorización "in
vivo" realizada mediante el captador de fuerzas. La evaluación de los
registros obtenidos muestra como en el período comprendido entre la 2ª y
3ª semana de evolución postoperatoria acontece un aumento rápido y muy
importante de la rigidez del callo, prevista por el estudio teórico.
La interpretación global de los resultados, tanto teóricos como experimentales,
plantea la necesidad de una rigidez del sistema de fijación
externa en las etapas iniciales de la consolidación que garantice una
protección mecánica del callo en dicho momento. El comportamiento de este sistema «rígido» es prácticamente idéntico al presentado por los
sistemas «elásticos», cuando el callo adquiere unas características elásticas
que permitan asumir su entrada en carga. Esto sucede transcurrido un
20% del tiempo de consolidación total de la fractura.To study the differences between rigid and elastic external fixation,
the authors have designed an external fixator, used at the
tibia of the rabbit, which allows a rigid behaviour and with the
possibility of transformation in an elastic system. They have carried
out a theoretical study of the fixator by 'finite elements'
method and an experimental study, biomechanical, morfological
and 'in vivo' monitoritation of the callus of fracture.
The theoretical study showed that the weights supported by
the fracture's callus depended on their elastic characteristics and
not on the immobilization method used (rigid or elastic).
At the fracture callus of the rabbit tibias there wer e no differences
of resistance to the traction with either methods (rigid or elastic).
There wer e also no histological differences in the evolution of
the callus.
The "in vivo" monitoritation through force measuranient show
ed a rapid increase in the rigidity of the callus between the
second and third week.
The overall interpretation of the results, both theoretical and
experimental, established the necessity of rigidity of the system of
external fixation in the initial estages of consolidation that garantices
a mechanical protection of the callus in that moment.
The behaviour of this "rigid" system is praticaly identical to
that presented by "elastic" systems, when the callus acquires some
elastic characteristics that permits it to support weights. This
occurs when more than 20 % of the total consolidation time of the
fracture has passed
Proteínas morfogenéticas óseas (BMPs): Efecto de la proteína osteogénica-1 (OP-l/BMP-7) en la condrogénesis y osteogenesis
En la actualidad, los estudios sobre biología molecular han facilitado el análisis de
ciertos factores de transformación del crecimiento tipo ß(TGF-ß)I, entre los que destaca una familia
de proteínas morfogenéticas óseas (BMPs). Las técnicas de ingeniería genética han permitido
replicar alguno de estos factores y localizar los genes que codifican dichas proteínas. La proteína
osteogenics-1 (OP-1) ha sido caracterizada y sintetizada in vitro y muestra un elevado potencial
osteogénico y condrogénico tanto in vivo como in vitro. Se presenta una revisión de los
últimos avances en la aplicación experimental de las BMPs, y especialmente de la OP-1, en el área
de la Cirugía Ortopédica y la TraumatologíaNowadays, molecular biology studies have promoted the bone morphogenetic
proteins (BMPs) analysis. These multifunctional proteins are structurally related to transforming
growth factor-6 (TGF-6). Genetic engineering techniques have allowed to sequence some of these
BMPs. It has been characterized the expression and processing of osteogenic protein-1 (OP-1),
a bone morphogenetic protein of the TGF-6 family. The OP-1 shows a high osteogenic and chondrogenic
potential. The aim of this paper is to review some updated advances of the BMPs experimental
applications, particularly OP-1, in relation to Orthopaedic Surgery and Traumatolog
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The contribution of tropical cyclones to the atmospheric branch of Middle America's hydrological cycle using observed and reanalysis tracks
Middle America is affected by tropical cyclones (TCs) from the Eastern Pacific and the North Atlantic Oceans. We characterize the regional climatology (1998-2016) of the TC contributions to the atmospheric branch of the hydrological cycle, from May to December. TC contributions to rainfall are quantified using Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42 and TC tracks derived from three sources: the International Best Track Archive for Climate Stewardship (IBTrACS), and an objective feature tracking method applied to the Japanese 55-year and ERA-Interim reanalyses. From July to October, TCs contribute 10-30% of rainfall over the west and east coast of Mexico and central Mexico, with the largest monthly contribution during September over the Baja California Peninsula (up to 90%). TCs are associated with 40-60% of daily extreme rainfall (above the 95th percentile) over the coasts of Mexico. IBTrACS and reanalyses agree on TC contributions over the Atlantic Ocean but disagree over the Eastern Pacific Ocean and continent; differences over the continent are mainly attributed to discrepancies in TC tracks in proximity to the coast and TC lifetime. Reanalysis estimates of TC moisture transports show that TCs are an important moisture source for the regional water budget. TC vertically integrated moisture flux (VIMF) convergence can turn regions of weak VIMF divergence by the mean circulation into regions of weak VIMF convergence. We discuss deficiencies in the observed and reanalysis TC tracks, which limit our ability to quantify robustly the contribution of TCs to the regional hydrological cycle
SAGE, Matemàtiques interactives a l’abast
L'objectiu bàsic del projecte és augmentar significativament les capacitats
d'autoaprenentatge dels estudiants de les assignatures de Matemàtiques del
primer curs dels graus en enginyeria. El programari SAGE i els materials
interactius creats haurien de cobrir aquest aspecte i alhora fer més atractiu
l'estudi de les Matemàtiques als estudiants.Peer Reviewe
Living arrangements and place of death of older people with cancer in England and Wales: a record linkage study
The main objectives of the study were to (1) see whether the household circumstances of people aged 50 years and over with cancer, and trends in these, differ from those of the rest of the population and (2) whether living arrangements and presence and health status of a primary coresident are associated with place of death among older people dying of cancer and those dying from other causes. The design included prospective record linkage study of people aged 50 years and over included in a 1% sample of the population of England and Wales (the Office for National Statistics Longitudinal Study). The main outcome measures comprised family and household type, and death at home. The household circumstances of older people with cancer were very similar to those of the rest of the population of the same age and both showed a large increase in living alone, and decrease in living with relatives, between 1981 and 1991. The primary coresident of cancer sufferers who did not live alone was in most cases a spouse, with much smaller proportions living with a child, sibling or other person. In all, 30% of spouse, and 23% of other, primary coresidents had a limiting long-term illness. Compared with people who lived alone in 1991, odds of a home death among those dying of cancer between 1991 and 1995 were highest for those who lived with a spouse who had no limiting long-term illness (odds ratio (OR) 2.52, 95% confidence interval (CI) 2.15-2.97) and raised for those living with a spouse with a long-term illness (OR 2.14, CI 1.79-2.56) and those living with someone else who was free of long-term illness (OR 2.13, CI 1.69-2.68). Higher socioeconomic status, both individual and area, was positively associated with increased chance of a home death, while older age reduced the chance of dying at home. The changing living arrangements of older people have important implications for planning and provision of care and treatment for cancer sufferers
The (in)visibility of gender knowledge in the Physical Activity and Sport Science Degree in Spain
This paper draws on research that aimed to explore the construction of gender relations in sport and physical education (PE) through a national study of Spanish university degree curricula. Spain is a useful case study through which to explore gender knowledge within sport and PE degrees, because, unlike many other countries, it has a common, national curriculum framework for its Physical Activity and Sport Science (PASS) degrees. In addition, it has recently passed a new law concerning the introduction of gender knowledge in higher education. Drawing on Bernstein’s (1990) framework of the pedagogic device, this paper examines how this higher education gender policy becomes recontextualised as universities and lecturers interpret and translate this into the pedagogical texts that make up the PASS curricula. Purposive sampling was used to select 16 of the 37 universities offering PASS degrees in 2012/2013. The research analysed 16 PASS documents at the degree level, and 763 individual subject handbooks. Using discourse analysis, the results showed where and how gender knowledge was incorporated and the extent to which the topic was presented coherently throughout the documents. The analysis revealed five categories of the (in)visibility of gender knowledge within the universities’ instructional discourse. Gender knowledge is largely ignored in PASS curricular documentation, appearing, at best, in highly superficial ways. Despite a national policy requirement on universities to incorporate gender knowledge, this study shows how recontextualisation processes within specific universities’ pedagogic devices operate to marginalise such perspectives within PASS curricula. The research also revealed the significance of individual agents committed to gender equity being situated, and having influence, throughout the pedagogic device. The paper concludes that without a much wider, critical engagement in knowledge about gender equity, PASS degrees will continue to reproduce rather than disrupt the gender relations that have traditionally characterised the field
Evaluation of quality of life in a palliative care context: an integrative literature review
Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.
PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks
Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study
PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks
APOE ɛ4 exacerbates age-dependent deficits in cortical microstructure
The apolipoprotein E ɛ4 allele is the primary genetic risk factor for the sporadic type of Alzheimer’s disease. However, the mechanisms by which apolipoprotein E ɛ4 are associated with neurodegeneration are still poorly understood. We applied the Neurite Orientation Dispersion Model to characterize the effects of apolipoprotein ɛ4 and its interactions with age and education on cortical microstructure in cognitively normal individuals. Data from 1954 participants were included from the PREVENT-Dementia and ALFA (ALzheimer and FAmilies) studies (mean age = 57, 1197 non-carriers and 757 apolipoprotein E ɛ4 carriers). Structural MRI datasets were processed with FreeSurfer v7.2. The Microstructure Diffusion Toolbox was used to derive Orientation Dispersion Index maps from diffusion MRI datasets. Primary analyses were focused on (i) the main effects of apolipoprotein E ɛ4, and (ii) the interactions of apolipoprotein E ɛ4 with age and education on lobar and vertex-wise Orientation Dispersion Index and implemented using Permutation Analysis of Linear Models. There were apolipoprotein E ɛ4 × age interactions in the temporo-parietal and frontal lobes, indicating steeper age-dependent Orientation Dispersion Index changes in apolipoprotein E ɛ4 carriers. Steeper age-related Orientation Dispersion Index declines were observed among apolipoprotein E ɛ4 carriers with lower years of education. We demonstrated that apolipoprotein E ɛ4 worsened age-related Orientation Dispersion Index decreases in brain regions typically associated with atrophy patterns of Alzheimer’s disease. This finding also suggests that apolipoprotein E ɛ4 may hasten the onset age of dementia by accelerating age-dependent reductions in cortical Orientation Dispersion Index
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