X-ray diffraction studies of muscle : observations on the anterior byssus retractor muscle of Mytilus edulis and the insect flight muscle from Sarcophaga bullata

The interfilament spacing of the anterior byssus retractor muscle from Mytilus edulis was studied as the muscle was extended. It was found that variations in this spacing were very small and consistent with the hypothesis that the interfilament spacing was independent of the extension of the muscle. It was observed that the interfilament spacing was dependent on the osmolarity of the bathing medium. In concentrated solutions of the artificial seawater, the interfilament spacing decreased; while in dilute solutions of artificial seawater, it was observed that the interfilament spacing was increasing. X-ray diffraction patterns were obtained from fresh, and glutaraldehyde fixed, specimens of insect flight muscle from Sarcophaga bullata. There patterns were in general agreement with previous X-ray diffraction studies of insect flight muscle. A reflexion G at 93A was observed and interpreted as arising from diffraction in the mitochondria. Specimens of dried insect flight muscle produced a diffraction pattern consisting of arc and ring reflexions. This was interpreted as suggesting an ordered arrangement of cristae, in the mitochondria from these muscles.

Electronic, magnetic and thermal properties of Pb₂₋x AxCrO₅ (A = K or La)

Lead chromium oxide is a photoconductive dielectric material tha t has great potential of being used as a room temperature photodetector. In this research, we made ceramic pellets of this compound as well as potassium doped compound Pb2-xKxCr05, where x=O, 0.05, 0.125. We also investigate the properties of the lanthanum doped sample whose chemical formula is Pb1.85Lao.15Cr05' The electronic, magnetic and thermal properties of these materials have been studied. Magnetization measurements of the Pb2Cr05 sample indicate a transition at about 310 K, while for the lanthanum doped sample the transition temperature is at about 295 K indicating a paramagnetic behavior. However, the potassium doped samples are showing the transition from paramagnetic state to diamagnetic state at different temperatures for different amounts of potassium atoms present in the sample. We have studied resistivity as a function of temperature in different gas environments from 300 K to 900 K. The resistivity measurement of the parent sample indicates a conducting to insulating transition at about 300 K and upon increasing the temperature further, above 450 K the sample becomes an ionic conductor. As temperature increases a decrease in resistance is observed in the lanthanum/potassium doped samples. Using Differential Scanning Calorimetry experiment an endothermic peak is observed for the Pb2Cr05 and lanthanum/potassium doped samples at about 285 K.

Recherche d’étoiles jeunes de faible masse dans le voisinage solaire

Formées lors de l’effondrement gravitationnel d’un nuage de gaz moléculaire, les étoiles naissantes auront différentes masses variant entre 0.08 et environ 100M . La majorité de la population stellaire de la Galaxie est constituée d’étoiles dont la masse est inférieure à environ 0.6 M . Le dernier évènement de formation stellaire dans le voisinage solaire s’est produit dans la bulle locale il y a au plus 100 millions d’années, vraisemblablement provoqué par le passage d’une onde de choc dans le bras local de la Galaxie. C’est ainsi que se formèrent de jeunes associations d’étoiles dont les membres se caractérisent en particulier par une vitesse spatiale et une position commune dans la Galaxie. Les associations jeunes étant peu densément peuplées et relativement proches du Soleil, leurs membres se font plutôt rares et dispersés sur toute la voûte céleste. Jusqu’à présent, surtout les étoiles les plus massives (brillantes) ont été répertoriées. Les étoiles jeunes de faible masse, constituant la majorité de la population, restent pour la plupart à être identifiées. Les étoiles jeunes de faible masse représentent une population clef pour contraindre les modèles évolutifs des étoiles M et des naines brunes. Elles sont également d’excellentes candidates pour chercher des exoplanètes via les techniques d’imagerie directe. Ce mémoire présente une nouvelle méthode utilisant un modèle cinématique enrichi d’une analyse statistique Bayesienne pour identifier des étoiles jeunes de faible masse dans les associations beta Pictoris, Tucana-Horologium et AB Doradus. À partir d’un échantillon de 1080 étoiles K et M, toutes comportant des indicateurs de jeunesse tels l’émission Halpha et une forte luminosité dans les rayons X, leurs propriétés cinématiques (mouvement propre) et photométriques sont analysées pour en extraire 98 candidates hautement probables membres d’une des trois associations. Une confirmation de leur statut comme membre nécessitera en particulier une mesure de leur vitesse radiale (prédit par notre analyse) et une mesure de la largeur équivalente du lithium à 6708 Å pour mieux contraindre leur âge.

3D registration of MR and X-ray spine images using an articulated model.

Présentation: Cet article a été publié dans le journal : Computerised medical imaging and graphics (CMIG). Le but de cet article est de recaler les vertèbres extraites à partir d’images RM avec des vertèbres extraites à partir d’images RX pour des patients scoliotiques, en tenant compte des déformations non-rigides due au changement de posture entre ces deux modalités. À ces fins, une méthode de recalage à l’aide d’un modèle articulé est proposée. Cette méthode a été comparée avec un recalage rigide en calculant l’erreur sur des points de repère, ainsi qu’en calculant la différence entre l’angle de Cobb avant et après recalage. Une validation additionelle de la méthode de recalage présentée ici se trouve dans l’annexe A. Ce travail servira de première étape dans la fusion des images RM, RX et TP du tronc complet. Donc, cet article vérifie l’hypothèse 1 décrite dans la section 3.2.1.

Influence of the buffer environment on the Relative Biological Effectiveness of carbon ion radiation, investigated by Scanning Force Microscopy and gel electrophoresis

This work focuses on the analysis of the influence of environment on the relative biological effectiveness (RBE) of carbon ions on molecular level. Due to the high relevance of RBE for medical applications, such as tumor therapy, and radiation protection in space, DNA damages have been investigated in order to understand the biological efficiency of heavy ion radiation. The contribution of this study to the radiobiology research consists in the analysis of plasmid DNA damages induced by carbon ion radiation in biochemical buffer environments, as well as in the calculation of the RBE of carbon ions on DNA level by mean of scanning force microscopy (SFM). In order to study the DNA damages, besides the common electrophoresis method, a new approach has been developed by using SFM. The latter method allows direct visualisation and measurement of individual DNA fragments with an accuracy of several nanometres. In addition, comparison of the results obtained by SFM and agarose gel electrophoresis methods has been performed in the present study. Sparsely ionising radiation, such as X-rays, and densely ionising radiation, such as carbon ions, have been used to irradiate plasmid DNA in trishydroxymethylaminomethane (Tris buffer) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES buffer) environments. These buffer environments exhibit different scavenging capacities for hydroxyl radical (HO0), which is produced by ionisation of water and plays the major role in the indirect DNA damage processes. Fragment distributions have been measured by SFM over a large length range, and as expected, a significantly higher degree of DNA damages was observed for increasing dose. Also a higher amount of double-strand breaks (DSBs) was observed after irradiation with carbon ions compared to X-ray irradiation. The results obtained from SFM measurements show that both types of radiation induce multiple fragmentation of the plasmid DNA in the dose range from D = 250 Gy to D = 1500 Gy. Using Tris environments at two different concentrations, a decrease of the relative biological effectiveness with the rise of Tris concentration was observed. This demonstrates the radioprotective behavior of the Tris buffer solution. In contrast, a lower scavenging capacity for all other free radicals and ions, produced by the ionisation of water, was registered in the case of HEPES buffer compared to Tris solution. This is reflected in the higher RBE values deduced from SFM and gel electrophoresis measurements after irradiation of the plasmid DNA in 20 mM HEPES environment compared to 92 mM Tris solution. These results show that HEPES and Tris environments play a major role on preventing the indirect DNA damages induced by ionising radiation and on the relative biological effectiveness of heavy ion radiation. In general, the RBE calculated from the SFM measurements presents higher values compared to gel electrophoresis data, for plasmids irradiated in all environments. Using a large set of data, obtained from the SFM measurements, it was possible to calculate the survive rate over a larger range, from 88% to 98%, while for gel electrophoresis measurements the survive rates have been calculated only for values between 96% and 99%. While the gel electrophoresis measurements provide information only about the percentage of plasmids DNA that suffered a single DSB, SFM can count the small plasmid fragments produced by multiple DSBs induced in a single plasmid. Consequently, SFM generates more detailed information regarding the amount of the induced DSBs compared to gel electrophoresis, and therefore, RBE can be calculated with more accuracy. Thus, SFM has been proven to be a more precise method to characterize on molecular level the DNA damage induced by ionizing radiations.

X-Ray spectra of superheavy and quasi-superheavy elements

We discuss the possibility of identifying superheavy elements from the observation of their M-shell x-ray spectra, which might occur during the collision of a superheavy element with a heavy target. The same question is discussed for the possible observation of the x-rays from the quasimolecule (quasi-superheavy element) which is formed during such a heavy-ion collision. It is shown that it is very difficult, if not impossible, to determine any information about the interesting quantum electrodynamical effects from the M-shell x-ray spectra of these quasimolecules.

Shifts of electronic KX-rays in muonic atoms

Energies of electronic K X-rays in muonic atoms were calculated for muons in various outer orbitals and for different numbers of electrons. Energy shifts were obtained with respect to characteristic X-rays belonging to nuclear charge (Z - 1) and their possible observation is discussed. The shifts in muonic Sn as an example amount to 19, 37, and 59 eV for the muon in 5g, 6h, and 7i states respectively. However, shifts due to the number of electrons present and the electron vacancy distribution in the L-shell are significantly larger. Accurate measurements of the K X-ray energies would therefore enable us to learn more about the electronic structure during the muonic cascade.

Nuclear charge radii from X-ray transitions in muonic atoms of carbon, nitrogen and oxygen

Energies of muonic X-rays of the K-series of carbon, nitrogen and oxygen have been measured with an accuracy of about 15 eV. Root mean square radii of the nuclear charge distributions were deduced. The results 2.49±0.05 fm for carbon, 2.55 ±0.03 fm for nitrogen and 2.71 ±0.02 fm for oxygen are in good agreement at comparable accuracy with recent electron scattering data.

Observation of two-electron-one-photon transitions in silicon

We report on the observation of K\alpha\alpha X-rays of Si, produced in collisions of 15-28 MeV Si projectiles with various target atoms in the range Z =6 to 29. Energy shifts of X-rays were measured and are compared with theoretical predictions. Cross section ratios for emission of K\alpha\alpha and K\alpha radiation are given.

Resultados en reducción abierta de cadera por via interna: necrosis avascular y concordancia interobservador

Introducción: la luxación típica de la cadera es una patología con alta incidencia, de ahí la necesidad de métodos efectivos para lograr una reducción de esta. Han surgido varios métodos de reducción, uno de estos métodos es la reducción abierta por vía interna. Metodología Estudió descriptivo retrospectivo, incluyo los casos operados de reducción abierta por vía interna en el Instituto de Ortopedia Infantil Roosevelt y Clínica Jorge Piñeros Corpas por uno de los tutores, desde enero de 2006 hasta junio de 2011, valorando estas caderas según los criterios de Salter de necrosis avascular (NAV), con un seguimiento mínimo de 18 meses. Se evaluó la concordancia interobservador para la clasificación de Salter en tres ortopedistas infantiles. Resultados Se evaluaron 20 caderas en 16 pacientes a los que se realizo reducción abierta de luxación típica de cadera por vía interna. El 40 % de las caderas presentaron NAV, el 75% de estas caderas presentan NAV tipo I según la clasificación de Kalamchi. El índice Kappa para la clasificación de Salter en tres ortopedistas infantiles fue 0.6. Discusión El abordaje por vía interna para la reducción de luxación de cadera típica en niños menores de 18 meses es una alternativa más para el manejo de estos pacientes, que puede producir NAV en la cadera, pero esta NAV es tipo I de Kalamchi en la mayoría de casos. La reproducibilidad de la radiografía para la evaluación de NAV, realizada por personas expertas es buena, medida con índice kappa de 0.6.

Concordancia interobservador entre ortopedistas de urgencias y cirujanos de codo en fracturas de cúpula radial

El trauma de codo y la fractura de cúpula radial resultan ser un motivo de consulta frecuente en nuestro medio. Es común en nuestro medio que a pesar de tener radiografías de codo en las que se evidencia fractura de cúpula radial se solicite un TAC de codo. Consideramos que el TAC es una herramienta útil en algunos casos de fracturas de la cúpula radial, es decir, no se debe tomar de forma rutinaria el TAC de codo en los pacientes con fracturas de cúpula radial como es usual en nuestro medio. Existen pocos estudios que comparan la concordancia inter observador de las clasificaciones utilizadas para las fracturas de cúpula radial, pero, no existe en la literatura mundial un estudio que evalué las diferencias entre la clasificación de la fractura en base a radiografías y tomografía entre un grupo ortopedistas traumatólogos y sub-especialistas de miembro superior. La realización de este estudio permite elaborar guías de manejo de pacientes con fractura de cúpula radial en la que se racionalizara el uso del TAC de codo.

¿La tomografía de codo cambia la conducta tomada previamente con radiografía en fracturas de cúpula radial? un estudio de concordancia

Las fracturas de la cúpula radial corresponden a un tercio de todas las fracturas del codo en adultos (1), por lo que se toman radiografías o tomografías, sin embargo no existe literatura que soporte la realización de la tomografía como estudio complementario, por lo que preguntamos ¿La tomografía de codo cambia la conducta tomada previamente con radiografía en fracturas de cúpula radial? Se propone un estudio de concordancia, donde se evalúan las radiografías y tomografías por parte de dos cirujanos de codo, de pacientes con diagnóstico de fractura de cúpula radial valorados en urgencias de dos hospitales de tercer nivel de Bogotá desde enero 2011 a enero 2013. Se revisaron 116 historias, 99 cumplieron los criterios, las radiografías fueron revisadas por dos ortopedistas de codo quienes realizaron clasificación de Mason obteniendo un κ 1 (p˂ 0,00), propuesta de tratamiento postradiografía κ 0,934 (p˂ 0,000 IC95% 0.85, 1). Tratamiento post-tomografía de codo κ 0.949 (p˂ 0,00 IC95% 0.867,1). Concordancia intra-ortopedista de la conducta pre y post-tomografía hay cambio en la conducta del ortopedista 1 en 32.6% (κ 0.674 p˂ 0,00 IC95% 0.52, 0.818) y del ortopedista 2 en 36% (κ 0.64 p˂ 0,00 IC95% 0.452, 0.792). Se dividieron los pacientes en Mason I, II, III con concordancia considerable en los pacientes Mason I y III, mientras que en Mason II fue una concordancia aceptable lo que significa que el uso de tomografía de codo cambia la conducta en general pero sobretodo en pacientes clasificados Masson II.

Prevalencia de neumoconiosis y su relación con medidas de higiene y seguridad industrial y niveles ambientales de carbón en minería subterránea en el departamento de Cundinamarca - Colombia, 2015

Introducción: La exposición en minas subterráneas a altos niveles de polvo de carbón está relacionada con patologías pulmonares. Objetivo: Determinar la prevalencia de neumoconiosis, medidas de higiene y seguridad industrial y su relación con niveles ambientales de carbón en trabajadores de minas de socavón en Cundinamarca. Materiales y Métodos: Estudio de corte transversal, en 215 trabajadores seleccionados mediante muestreo probabilístico estratificado con asignación proporcional. Se realizaron monitoreos ambientales, radiografías de tórax y encuestas con variables sociodemográficas y laborales. Se emplearon medidas de tendencia central y dispersión y la prueba de independencia ji-cuadrado de Pearson o pruebas exactas, con el fin de establecer las asociaciones. Resultados: El 99,5% de la población perteneció al género masculino, el 36,7% tenía entre 41-50 años, con un promedio de años de trabajo de 21,70 ± 9,99. La prevalencia de neumoconiosis fue de 42,3% y la mediana de la concentración de polvo de carbón bituminoso fue de 2,329670 mg/m3. El índice de riesgo de polvo de carbón presentó diferencias significativas en las categorías de bajo (p=0,0001) y medio (p=0,0186) con la prevalencia de neumoconiosis. El 84,2% reporto no usar mascarilla. No se presentan diferencias entre los niveles de carbón (p=0,194) con la prevalencia de neumoconiosis. Conclusiones: Se encontró una prevalencia de neumoconiosis de 42,3% en Cundinamarca. Se requiere contar con medidas de higiene y seguridad industrial efectivas para controlar el riesgo al que están expuestos los mineros de carbón por la inhalación de polvo de carbón.

Hints for a fast precessing relativistic radio jet in LS I + 61° 303

Here we discuss two consecutive MERLIN observations of the X-ray binary LS I +61° 303 . The first observation shows a double-sided jet extending up to about 200 AU on both sides of a central source. The jet shows a bent S-shaped structure similar to the one displayed by the well-known precessing jet of SS 433 . The precession suggested in the first MERLIN image becomes evident in the second one, showing a one-sided bent jet significantly rotated with respect to the jet of the day before. We conclude that the derived precession of the relativistic (beta=0.6) jet explains puzzling previous VLBI results. Moreover, the fact that the precession is fast could be the explanation of the never understood short term (days) variability of the associated gamma-ray source 2CG 135+01 / 3EG J0241+6103

Incidência de lesões locomotoras no cavalo, diagnosticadas por raio-x

Na medicina equina, os problemas locomotores estão na origem da maioria das consultas veterinárias, provocando uma enorme preocupação para os proprietários e equitadores e exigindo um grande conhecimento por parte do veterinário. Assim, não são demais os estudos realizados nesta área, que permitem auxiliar os médicos veterinários sempre que se deparam com este tipo de problemas. Uma das ferramentas fundamentais para o diagnóstico das lesões ósseas e articulares nos membros é o raio-X. Desde que este foi tornado portátil, passou a ser um enorme aliado do veterinário, permitindo diagnósticos mais facilitados e imediatos no terreno. O objectivo da presente dissertação, para além de rever a bibliografia descrita acerca da incidência de lesões locomotoras, é também contribuir para a caracterização das lesões mais frequentes na medicina equina na população estudada que envolvam as estruturas óssea e articular dos membros do cavalo. As lesões locomotoras descritas no estudo, foram determinadas após uma observação rigorosa aos diferentes raios-X de 95 cavalos e os dados recolhidos foram tratados através de uma análise estatística utilizando o programa «SPSS®». Existe uma maior incidência de lesões nos membros anteriores quando comparado com os membros posteriores. Tanto o membro anterior direito, como o membro posterior direito são igualmente mais afectados do que os membros esquerdos, havendo também uma elevada distribuição das lesões em ambos os membros anteriores em simultâneo. No membro anterior, a lesão mais frequentemente diagnosticada é a osteoartrite, sendo a luxação uma das lesões menos encontradas. Para o membro posterior, é o esparvão que mais se diagnostica, contrastando com o síndrome podotroclear, que tem uma prevalência baixa. No membro anterior, a 3ª falange é uma das regiões mais afectadas, sendo a ulna uma das regiões menos afectadas. No membro posterior, é a região do curvilhão que representa um dos locais mais propícios a lesão, enquanto a 2ª falange é uma das regiões onde menos frequentemente se diagnosticam lesões no cavalo. Os resultados encontrados estão de acordo com a bibliografia descrita e sugerem a importância da continuidade deste tipo de estudos, nomeadamente abrangendo outras variáveis como a raça, a idade e o tipo de utilização do cavalo e, ainda, a utilização de outros métodos imagiológicos.