Water fragmentation by bare and dressed light ions with MeV energies: Fragment-ion-energy and time-of-flight distributions

The energy and time-of-flight distributions of water ionic fragments produced by impact of fast atoms and bare and dressed ions; namely, H+, Li0-3+, C1+, and C2+ are reported in this work. Fragment species as a function of emission energy and time-of-flight were recorded by using an electrostatic spectrometer and a time-of-flight mass spectrometer, respectively. An improved Coulomb explosion model coupled to a classical trajectory Monte Carlo (CTMC) simulation gave the energy centroids of the fragments for the dissociation channels resulting from the removal of two to five electrons from the water molecule. For the energy distribution ranging up to 50 eV, both the experiment and model reveal an isotropic production of multiple charged oxygen ions, as well as hydrogen ions. From the ion energy distribution, relative yields of the dissociation resulting from multiple ionization were obtained as a function of the charge state, as well as for several projectile energies. Multiple-ionization yields with charge state up to 4+, were extracted from the measurements of the time-of-flight spectra, focused on the production of single and multiple charged oxygen ions. The measurements were compared to ion-water collision experiments investigated at the keV energy range available in the literature, revealing differences and similarities in the fragment-ion energy distribution.Fil: Wolff, W.. Universidade Federal do Rio de Janeiro; BrasilFil: Luna, H.. Universidade Federal do Rio de Janeiro; BrasilFil: Schuch, R.. Alba Nova University Center; SueciaFil: Cariatore, Nelson Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Otranto, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Turco, Federico. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Fregenal, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Bernardi, Guillermo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Suárez, S.. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Influencia de la vía de abordaje y de posición de la cúpula acetabular en la luxación de la artroplastia total de cadera: estudio caso-control

Tanto la vía de acceso quirúrgica como la posición de los componentes se han relacionado con la presencia de una luxación en las artroplastias primarias de cadera. Hemos estudiado la presencia de esta complicación en una serie de 758 artroplastias no cementadas modelo Bihapro. Encontramos 21 luxaciones. Por otro lado se seleccionó de forma aleatoria un grupo de control de 42 pacientes que no habían presentado luxación. Se diseñó un estudio de casos y controles que englobaba por tanto a 63 pacientes que tenían implantada una artroplastia de este modelo. En el grupo de casos observamos que el porcentaje de luxación fue sensiblemente mayor en el sexo masculino con un 66,7%, en comparación con el sexo femenino que fue de un 42,8% aunque esta diferencia no fue estadísticamente significativa. No se observaron diferencias en la frecuencia de luxaciones en relación con la vía anterior o lateral, pero sin embargo en la vía posterior la luxación se produjo en un solo caso (4,8% de todas las luxaciones) con una incidencia claramente menor que en los abordajes anterior y lateral, siendo esta diferencia estadísticamente significativa (p=0,005). También observamos diferencias estadísticamente significativas en cuanto a un mayor porcentaje de luxaciones cuando la inclinación del componente acetabular era mayor de 50º (76,2%), o cuando la anteversión del cotilo era mayor o igual a 20º (54,4%). La vía de abordaje posterior con reconstrucción capsular y muscular presenta un menor porcentaje de luxación después de una artroplastia primaria en comparación con la anterior o lateral. Una inclinación mayor de 50º o una anteversión mayor de 20º favorecen la presencia de una luxación.The surgical approach and the cup position have been related with the dislocations of total hip arthroplasty. We have studied the presence of this complication in 758 Bihapro™ cementless arthroplasties. We got a case group of 21 dislocations; then we selected a control group of 42 patients without luxation to design a case-control study. The case group had a higher rate of dislocation in males (66.7 % versus 42.8 % in females) although this difference was not statistically significant. We didn’t observe any difference in the frequency of luxations relating to the anterior or lateral surgical approach, however in the posterior approach the dislocation appeared only in one case (4.8 % of the all dislocations) with statistically differences (p=0.005). We also observed statistically significant differences of luxations when the acetabular cup inclination was higher than 50º (76.2 %), or when the cup anteversion was equal or higher than 20º (52.4 %). The posterior surgical approach with capsular and muscular suture presented a lower rate of dislocation after a primary arthroplasty compared with the anterior or lateral approachs. An inclination bigger than 50º or an anteversion bigger than 20º seems to be a risk factor of luxation

Influencia de la inclinación acetabular en la luxación de la artroplastia parcial de cadera

La luxación de la prótesis parcial de cadera, representa en la actualidad un grave problema de incapacidad para el paciente, debido no solo, a la complicación de la marcha en sí, sino a todas aquellas derivadas de la estancia hospitalaria de estos pacientes en nuestros centros. Respecto a la vía de abordaje, se ha sentado una mayor incidencia de luxaciones en la vía posterolateral, frente a las anteriores o laterales transtrocantéreas en decúbito supino. Objetivo: evaluar la influencia del ángulo de inclinación anatómico del acetábulo, techo y cobertura en la luxación de la artroplastia parcial de cadera. Material y método: el estudio incluyó un total de 718 pacientes intervenidos por fractura cervical de fémur, durante los años de 1992 a 2005. Las prótesis parciales implantadas fueron del modelo Thompson; los tipos de vías de abordaje quirúrgico utilizados fueron; la anterior de Smith Petersen, y la posterior de Gibson Moore. Se realizaron las mediciones radiográficas del ángulo formado entre las línea trazada en el borde externo del acetábulo y la línea biisquiática. Resultados: Del total de pacientes incluidos en el estudio el número de luxaciones fue de 24 prótesis, lo que representa el 3,3 %. La edad media fue de 84 años, y un intervalo de 76 a 92 años. El sexo predominante fue el femenino con un 83%. La vía más utilizada fue la anterior con un 67 %. El mayor porcentaje de luxación fue para aquellas pacientes con un ángulo de inclinación anatómico del acetábulo de > 55º. El tiempo medio seguimiento hasta producirse la luxación fue de 35 días y un intervalo entre 1 a 89 días. El tratamiento más frecuente fue el conservador 88%. Conclusión: El presente estudio demuestra que la luxación temprana de una prótesis parcial de cadera está directamente relacionado con un ángulo de inclinación anatómico del acetábulo mayor de 55º.The dislocation of partial hip replacements represents an important postoperative complication. Apart from the most important problem which is patient mobility, another aspect is the prolonged hospital stay detrimental to patient health and the evonawy of hospital. With respect to the incidence of pos- toperative dislocations and the type of surgical approach, it seated that there is a greater incidence using the lateroposterior hip sur- gical approach, in comparision to the anterior or lateral access. Objective: To evidence the influence of acetabular inclination in postoperative dislocations of partial hip arthroplasty. Methods: A study involuing 718 cases of intervened femoral neck fractures using Thompson endoprosthesis during the period including 1992 to 2005.With respect to type of surgical approaches, these included the Smith-Petersen anterior and the Gibson-Moore posterior access. The acetabular inclination was measurements radiologi- cally, obtaining the angle between the bi-ischial line and the exter- nal border of the acetabulum. Results: A total of twentyfour (24) prosthesis suffered dislocation, with respect to the total of seven hundred and eighteen (718) patients intervened for partial hip arth- roplasty, representing 3,3% of the total. The average age for dislocated arthroplasties was 84 years, with a range between 76-92 years, and the predominant sex was female. Concerning surgical access, the anterior was the most frecuently used (67%). There was found to be a greater percentage of dislo- cated arthroplasties when the angle of acetabular inclination exce- eded fifty five (55º) degrees. The average time elapsed before dis- location was diagnosed included a 35 days time period, with a range between to 89 days. The most frequent management of pos- toperative dislocations was conservative treatment. Conclusion: This study demonstrates that when the acetabular inclination is greater than 55º, there is a greater incidence of early dislocation of partial hip replacements

Observational Δν\Delta\nu-ρˉ\bar\rho relation for δ\delta Sct stars using eclipsing binaries and space photometry

Delta Scuti ($\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise determination of global stellar parameters. In this work, we used space photometry observations of eclipsing binaries with a $\delta$ Sct component to obtain reliable physical parameters and oscillation frequencies. Using that information, we derived an observational scaling relation between the stellar mean density and a frequency pattern in the oscillation spectrum. This pattern is analogous to the solar-like large separation but in the low order regime. We also show that this relation is independent of the rotation rate. These findings open the possibility of accurately characterizing this type of pulsator and validate the frequency pattern as a new observable for $\delta$ Sct stars.Comment: 11 pages, including 2 pages of appendix, 2 figures, 2 tables, accepted for publication in ApJ

Tumor en hueco poplíteo en 1 niño: diagnóstico diferencial a propósito de 1 caso

Se presenta 1 caso de tumoración en hueco poplíteo en 1 paciente de 15 años de edad. En la exploración clínica inicial encontramos una tumoración de consistencia dura sin signos inflamatorios. Los estudios con RNM y gammagrafía ósea nos orientaban hacia una patología benigna. El estudio anatomopatológico realizado tras la exéresis de la tumoración lo caracterizó como zona de necrosis isquémica con calcificación distrófica de la inserción muscular del tendón del músculo semitendinoso.A 15-year-old boy with a poplited tumor in the knee is presented. The initial exploration showed a firm mass without inflammatory signs. RNM and bone scintigraphy disclosed benign pathology. The pathological diagnosis showed a central area of isquemic necrosis, with distrofic calcification of the semitendinous muscle

Epidemiología de las fracturas de la extremidad proximal del fémur en asturias

Hemos realizado un estudio epidemiológico de las fracturas de fémur proximal en personas mayores de 50 años, atendidas en nuestro Hospital durante los años 1990-92. Se valoraron un total de 355 casos. En el período estudiado se observó que las fracturas más numerosas fueron la cervicales, no encontrando diferencias significativas en los ingresos según el período estacional. La edad media de presentación fue de 81 años. La tasa de incidencia fue muy semejante a las otras provincias españolas y menor que la encontrada en los países del Norte de Europa, Inglaterra y Estados Unidos.We have performed an epidemiologic study on the incidence of proximal femoral fractures in patients older than 50 years, all reviewed in our Hospital from 1990 to 1992. We included 355 patients. Femoral neek fractures were the most frequent lesions. No significant differences in the hospital admissions were found during all the year's seasons. The mean age of presentation was 81 years. The incidence rate was similar to the rest of Spain, and less than in North Europe, England and United States

Historical biogeography of the neotropical Diaptomidae (Crustacea:Copepoda)

Introduction: Diaptomid copepods are prevalent throughout continental waters of the Neotropics, yet little is\ud known about their biogeography. In this study we investigate the main biogeographical patterns among the\ud neotropical freshwater diaptomid copepods using Parsimony Analysis of Endemicity (PAE) based on species records\ud within ecoregions. In addition, we assess potential environmental correlates and limits for species richness.\ud Results: PAE was efficient in identifying general areas of endemism. Moreover, only ecoregion area showed a\ud significant correlation with diaptomid species richness, although climatic factors were shown to provide possible\ud upper limits to the species richness in a given ecoregion.\ud Conclusion: The main patterns of endemism in neotropical freshwater diaptomid copepods are highly congruent\ud with other freshwater taxa, suggesting a strong historical signal in determining the distribution of the family in the\ud Neotropics.We would like to thank to Professor Edinaldo Nelson dos Santos Silva (INPA, Brazil) for useful insight during this study. We also thank FAPESP (process 2008/02015-7, 2009/00014-6, 2011/18358-3) for financial support to GPN; and CNPq for financial support to DP (process 141702/2006-0) and MRP (process 304897/2012-4)

The effect of injectable biocompatible elastomer (PDMS) on the strength of the proximal fixation of endovascular aneurysm repair grafts: An in vitro study

PurposeOne of the major concerns in the long-term success of endovascular aneurysm repair (EVAR) is stent graft migration, which can cause type I endoleak and even aneurysm rupture. Fixation depends on the mechanical forces between the graft and both the aortic neck and the blood flow. Therefore, there are anatomical restrictions for EVAR, such as short and angulated necks. To improve the fixation of EVAR grafts, elastomer (PDMS) can be injected in the aneurysm sac. The support given by the elastomer might prevent dislocation and migration of the graft. The aim of this study was to measure the influence of an injectable biocompatible elastomer on the fixation strength of different EVAR grafts in an in vitro model.MethodsThe proximal part of three different stent grafts was inserted in a bovine artery with an attached latex aneurysm. The graft was connected to a tensile testing machine, applying force to the proximal fixation, while the artery with the aneurysm was fixated to the setup. The force to obtain graft dislodgement (DF) from the aorta was recorded in Newtons (N). Three different proximal seal lengths (5, 10, and 15 mm) were evaluated. The experiments were repeated after the space between the graft and the latex aneurysm was filled with the elastomer. Independent sample ttests were used for the comparison between the DF before and after elastomer treatment for each seal length.ResultsThe mean DF (mean ± SD) of all grafts without elastomer sac filling for a proximal seal length of 5, 10, and 15 mm were respectively, 4.4 ± 3.1 N, 12.2 ± 10.6 N, and 15.1 ± 6.9 N. After elastomer sac filling, the dislodgement forces increased significantly (P < .001) to 20.9 ± 3.8 N, 31.8 ± 9.8 N, and 36.0 ± 14.1 N, respectively.ConclusionsThe present study shows that aneurysm sac filling may have a role as an adjuvant procedure to the present EVAR technique. The strength of the proximal fixation of three different stent grafts increases significantly in this in vitro setting. Further in vivo research must be done to see if this could facilitate the treatment of aneurysms with short infrarenal necks.Clinical RelevanceStent graft migration and endoleak due to suboptimal fixation are major drawbacks of currently available stent grafts. Optimizing the proximal fixation by peri-graft elastomer aneurysm sac filling may lead to lower incidence of graft migration and endoleak. It might make endovascular aneurysm repair available to larger group of patients with an abdominal aortic aneurysm

Accurate ρ̄ and log g of δ Sct stars using Asteroseismology

In this work, we present a new method to determine the surface gravity of δ Sct stars. We used a refined Δν=ρ̄ relation and the stellar parallaxes or luminosities to determine their masses and radii. A comparison with the data obtained from the binary analysis, has shown that the values found by both methods are equivalent, within the uncertainties. Moreover, thanks to the refined relation, the uncertainties in log g are of the order of those usually estimated with high-resolution spectroscopy. Because of that, this new method to determine the surface gravity is an important step forward to break the degeneracy problem in the spectroscopic analysis.AGH acknowledges support from Fundação para a Ciência e a Tecnologia (FCT,Portugal) through the fellowship SFRH/BPD/80619/2011 and from grant UID/FIS/04434/2013.AGH, MJPFGM and JCS acknowledge support from the EC Project SPACEINN (FP7-SPACE-2012-312844) .JCSalsoacknowledges funding support from the Spanish “Ministerio de Economía y Competitividad” under“Ramón y Cajal”subprogram. This research made use of the SIMBAD database and the VizieR catalogue access tool operated at CDS, Strasbourg, France, and the SAO/NASA Astrophysics Data System