Comportamiento biológico intraarticular de distintos aloinjertos tendinosos: estudio experimental

Se ha efectuado un estudio experimental comparativo, con valoración macro y microscópica, de la supervivencia, dentro de la articulación de la rodilla del conejo, de tendones flexores sobre extensores y dentro de estos, entre tendones conservados en fresco, congelados, liofilizados y fijados en solución de glutaraldehido al 0,2%. Los tendones se mantuvieron libres en la articulación receptora durante periodos distintos de tiempo. Entre los resultados destaca la pérdida de volumen, en el tiempo, de la masa tendinosa (18% de despariciones totales, con un 28% de pérdida final global). Los tendones fijados en glutaraldehido fueron los que presentaron menor pérdida de volumen. Los tendones implantados en fresco y los congelados presentaron una mayor tasa de infección. La mejor respuesta de supervivencia se detectó en los tendones conservados en glutaraldehido y los congelados. Así mismo, tenían más posibilidades de sobrevivir los flexores que los extensores. Desde el punto de vista histológico, los tendones conservados en fresco desencadenaron una mayor respuesta inflamatoria, con gran alteración estructural. Desde el punto de vista microscópico no se han hallado diferencias significativas entre flexores y extensores.Different groups of flexor and extensor tendons have been compared in their abitihty survive within the rabbit knee joint. Tendons were grouped and compared according four different storage procedures like freezing, lyophylization and fixation in 0,2% glutaraldehid. Some of them were used in fresh. All tendons have been kept inside the joint as free graft. All specimens lost weight along the study (18% of total loosing of specimen, and 28% of global loosing). Tendons fixed in disclosed less loosing of volume. Allograft infection was related to the method o glutaraildehid of storage, relationship being statistically significant (fresh tendons and frozen tendons were infected more easily). The best survival was found in both frozen and glutaraldehid fixed tendons. Flexor tendons show more chances of survival than extensors tendons. Histologically, fresh tendons disclosed the greatest inflammatory reaction. Opposite to the macroscopic findings, there were no significant differences between flexors and extensors tendons in the microscopical study

Efecto de la congelación en rodillas animales. Estudio biomecánico experimental

Se estudia el comportamiento mecánico de rodillas animales que han sido congeladas en 1 o varias ocasiones mediante la aplicación de cargas axiales hasta la fractura o test destructivos. Se analizan el tipo y localización de fracturas aparecidas mediante un estudio radiográfico.We study the mechanical behavior in animal knees who are fresh frozen in one or various times. Axial loading are applied until the final fracture ( destructive test). Also it evaluates the tipe and localization of the fractures with radiological study

Microwave Background Anisotropies and Nonlinear Structures I. Improved Theoretical Models

A new method is proposed for modelling spherically symmetric inhomogeneities in the Universe. The inhomogeneities have finite size and are compensated, so they do not exert any measurable gravitational force beyond their boundary. The region exterior to the perturbation is represented by a Friedmann-Robertson-Walker (FRW) Universe, which we use to study the anisotropy in the cosmic microwave background (CMB) induced by the cluster. All calculations are performed in a single, global coordinate system, with nonlinear gravitational effects fully incorporated. An advantage of the gauge choices employed here is that the resultant equations are essentially Newtonian in form. Examination of the problem of specifying initial data shows that the new model presented here has many advantages over `Swiss cheese' and other models. Numerical implementation of the equations derived here is described in a subsequent paper.Comment: 10 pages, 4 figures; Monthly Notices of the Royal Astronomical Society (MNRAS), in pres

Neutrino Halos in Clusters of Galaxies and their Weak Lensing Signature

We study whether non-linear gravitational effects of relic neutrinos on the development of clustering and large-scale structure may be observable by weak gravitational lensing. We compute the density profile of relic massive neutrinos in a spherical model of a cluster of galaxies, for several neutrino mass schemes and cluster masses. Relic neutrinos add a small perturbation to the mass profile, making it more extended in the outer parts. In principle, this non-linear neutrino perturbation is detectable in an all-sky weak lensing survey such as EUCLID by averaging the shear profile of a large fraction of the visible massive clusters in the universe, or from its signature in the general weak lensing power spectrum or its cross-spectrum with galaxies. However, correctly modeling the distribution of mass in baryons and cold dark matter and suppressing any systematic errors to the accuracy required for detecting this neutrino perturbation is severely challenging.Comment: 13 pages, 11 figures. Submitted to JCA

Microwave background anisotropies and non-linear structures II. Numerical computations

A new method for modelling spherically symmetric inhomogeneities is applied to the formation of clusters in an expanding Universe. We impose simple initial velocity and density perturbations of finite extent and we investigate the subsequent evolution of the density field. Photon paths are also calculated, allowing a detailed consideration of gravitational lensing effects and microwave background anisotropies induced by the cluster. We apply the method to modelling high-redshift clusters and, in particular, we consider the reported microwave decrement observed towards the quasar pair PC1643+4631 A&B. We also consider the effect on the primordial microwave background power spectrum due to gravitational lensing by a population of massive high-redshift clusters.Comment: 15 pages, 23 figures; Monthly Notices of the Royal Astronomical Society (MNRAS), in pres

Microwave background anisotropies due to non-linear structures in open and Lambda universes

A new method arising from a gauge-theoretic approach to general relativity is applied to the formation of clusters in an expanding universe. The three cosmological models (Omega_0=1, Omega_Lambda=0), (Omega_0=0.3, Omega_Lambda=0.7), (Omega_0=0.3, Omega_Lambda=0) are considered, which extends our previous application (Lasenby et al. 1999 -"http://xxx.soton.ac.uk/abs/astro-ph/9810123"-, Dabrowski et al. 1999 -"http://xxx.soton.ac.uk/abs/astro-ph/9810149"-). A simple initial velocity and density perturbation of finite extent is imposed at the epoch z=1000 and we investigate the subsequent evolution of the density and velocity fields for clusters observed at redshifts z=1, z=2 and z=3. Photon geodesics and redshifts are also calculated so that the Cosmic Microwave Background (CMB) anisotropies due to collapsing clusters can be estimated. We find that the central CMB temperature decrement is slightly stronger and extends to larger angular scales in the non-zero Omega_Lambda case. This effect is strongly enhanced in the open case. Gravitational lensing effects are also considered and we apply our model to the reported microwave decrement observed towards the quasar pair PC 1643+4631 A & B.Comment: 9 pages, 9 figures. Submitted to Monthly Notices of the Royal Astronomical Society (MNRAS

The Tully-Fisher relation of distant cluster galaxies

We have measured maximum rotation velocities (Vrot) for a sample of 111 emission-line galaxies with 0.1 < z < 1, observed in the fields of 6 clusters. From these data we construct 'matched' samples of 58 field and 22 cluster galaxies, covering similar ranges in redshift (0.25 < z < 1.0) and luminosity (M_B < -19.5 mag), and selected in a homogeneous manner. We find the distributions of M_B, Vrot, and scalelength, to be very similar for the two samples. However, using the Tully-Fisher relation (TFR) we find that cluster galaxies are systematically offset with respect to the field sample by -0.7+-0.2 mag. This offset is significant at 3 sigma and persists when we account for an evolution of the field TFR with redshift. Extensive tests are performed to investigate potential differences between the measured emission lines and derived rotation curves of the cluster and field samples. However, no such differences which could affect the derived Vrot values and account for the offset are found. The most likely explanation for the TFR offset is that giant spiral galaxies in distant clusters are on average brighter, for a given rotation velocity, than those in the field. We discuss the potential mechanisms responsible for this, and consider alternative explanations.Comment: 19 pages, 13 figures, accepted by MNRA

Beneficial effects of word final stress in segmenting a new language: evidence from ERPs

Background: How do listeners manage to recognize words in an unfamiliar language? The physical continuity of the signal, in which real silent pauses between words are lacking, makes it a difficult task. However, there are multiple cues that can be exploited to localize word boundaries and to segment the acoustic signal. In the present study, word-stress was manipulated with statistical information and placed in different syllables within trisyllabic nonsense words to explore the result of the combination of the cues in an online word segmentation task. Results: The behavioral results showed that words were segmented better when stress was placed on the final syllables than when it was placed on the middle or first syllable. The electrophysiological results showed an increase in the amplitude of the P2 component, which seemed to be sensitive to word-stress and its location within words. Conclusion: The results demonstrated that listeners can integrate specific prosodic and distributional cues when segmenting speech. An ERP component related to word-stress cues was identified: stressed syllables elicited larger amplitudes in the P2 component than unstressed ones

Hydrodynamical simulations of the Sunyaev-Zel'dovich effect: cluster scaling relations and X-ray properties

The Sunyaev-Zel'dovich effect is a powerful new tool for finding and studying clusters at high redshift, particularly in combination with their X-ray properties. In this paper we quantify the expected scaling relations between these properties using numerical simulations with various models for heating and cooling of the cluster gas. For a Non-radiative model, we find scaling relations in good agreement with self-similar predictions: $Y\propto T_X^{5/2}$ and $Y \propto L_X^{5/4}$. Our main results focus on predictions from Cooling and Preheating simulations, shown by Muanwong et al. (2002) to provide a good match to the X-ray scaling relations at z=0. For these runs we find slopes of approximately Y \proptoT_X^3 and $Y \propto L_X$, steeper and flatter than the self-similar scalings respectively. We also study the redshift evolution of the scaling relations and find the slopes show no evidence of evolution out to redshifts well beyond one, while the normalizations of relations between the SZ signal and X-ray properties do show evolution relative to that expected from self-similarity, particularly at z<1.Comment: 8 pages LaTeX file with eight figures incorporated. Minor changes following referee's comments, one reference added. Matches published versio

J0454-0309: Evidence for a strong lensing fossil group falling into a poor galaxy cluster

We have discovered a strong lensing fossil group (J0454) at z=0.26, projected near the well-studied cluster MS0451-0305. Using multicolour Subaru/Suprime-Cam and CFHT/Megaprime imaging together with Keck spectroscopy we identify member galaxies. A VLT/FORS2 spectrum was taken to determine the redshifts of the brightest elliptical and the lensed arc. Using HST/ACS images we determine the group's weak lensing signal and model the strong lens system. This is the first time that a fossil group is analysed with lensing methods. The X-ray luminosity and temperature are derived from XMM-Newton data. We find two filaments extending over 4 Mpc, and within the virial radius we identify 31 members spectroscopically and 33 via the red sequence with i<22 mag. They segregate into spirals and a dynamically cooler central concentration of ellipticals with a velocity dispersion of 480 km/s. Weak lensing and cluster richness relations yield r200 = 830 kpc and M200 = 0.85 x 10^14 Msun. The brightest group galaxy (BGG) is inconsistent with the dynamic centre of J0454. It strongly lenses a galaxy at z~2.1, and we model the lens with a pseudo-isothermal elliptical mass distribution. A large external shear requires that the BGG must be offset from J0454's dark halo centre by at least 90-130 kpc. The X-ray halo is offset by 24 kpc from the BGG, shows no signs of a cooling flow and is well described by a beta-model. With L = 1.4 x 10^43 erg/s J0454 falls well onto standard X-ray cluster scaling relations, but appears cooler (1.1 keV) than expected (2 keV). We conclude that J0454 consists of two systems, a sparse cluster and an infalling fossil group, the latter seeding the BCG. An alternative explanation is that galaxies in a filament, projected along the line of sight, stream towards the denser fossil group.Comment: 20 pages, 17 figures; Identical to the publication in A+A. Small language corrections. Minor additions: We check the influence of individual galaxy haloes to the external shear (Sect. 8.1.1). Alternative interpretation of the data: Galaxies ina filament projected along the l.o.s. fall into the fossil group (Section 8.1.2