The Kyiv Meridian Axial Circle Catalogue of stars in fields with extragalactic radio sources

A catalogue of astrometric (positions, proper motions) and photometric (B, V, R, r', J) data of stars in fields with ICRF objects has been compiled at the Observatory of the National Academy of Sciences of Ukraine and the Kyiv University Observatory. All fields are located in the declination zone from 0 to +30 degrees; the nominal field size is 46' (right ascension) x 24' (declination). The observational basis of this work is 1100 CCD scans down to V=17 mag which were obtained with the Kyiv meridian axial circle in 2001-2003. The catalogue is presented in two versions. The version KMAC1-T contains 159 fields (104 796 stars) and was obtained with reduction to the Tycho2 catalogue. For another 33 fields, due to a low sky density of Tycho2 stars, the reduction was found to be unreliable. Transformation to the ICRF system in the second version of the catalogue (KMAC1-CU) was performed using the UCAC2 and CMC13 catalogues as a reference; it contains 115 032 stars in 192 fields and is of slightly better accuracy. The external accuracy of one catalogue position is about 50-90 mas for V < 15 mag stars. The average error of photometry is better than 0.1 mag for stars down to 16 mag.Comment: 13 pages, 19 figure

Time-Resolved Photometry of Kuiper Belt Objects: Rotations, Shapes and Phase Functions

We present a systematic investigation of the rotational lightcurves of trans-Neptunian objects based on extensive optical data from Mauna Kea. Four of 13 objects (corresponding to 31%) in our sample ((33128) 1998 BU48, 2000 GN171, (20000) Varuna and 1999 KR16) were found to exhibit lightcurves with peak-to-peak range > 0.15 magnitude. In a larger sample obtained by combining our data with reliably determined lightcurves from the literature, 7 of 22 objects (32%) display significant (> 0.15 magnitude range) lightcurves. About 23% of the sampled objects have lightcurve ranges > 0.4 magnitudes. Curiously, the objects are very large (> 250 km diameter, assuming an albedo of 0.04) and, in the absence of rotation, should be near spherical due to self compression. We propose that the large amplitude, short period objects are rotationally distorted, low density rubble piles. Statistically, the trans-Neptunian objects are less spherical than their main-belt asteroid counterparts, indicating a higher specific angular momentum perhaps resulting from the formation epoch. In addition to the rotational lightcurves, we measured phase darkening for 7 Kuiper Belt objects in the 0 to 2 degree phase angle range. Unlike Pluto, the measured values show steep slopes and moderate opposition surge indicating backscatter from low albedo porous surface materials.Comment: 22 pages, 33 figures, 12 tables, To appear in AJ sept. 200

Long-term optical variability of the blazars PKS 2005-489 and PKS 2155-304

We present optical light curves for the period 1996-2000, of two of the brightest known EGRET BL Lac objects: PKS 2005-489 and PKS 2155-304, the latter also one of the few known TeV sources. For both objects, quiescent epochs of low level of variability were followed by active periods, without any indication of periodicity. In PKS 2005-489, several variability events with duration of about 20 days were observed. In PKS 2155-304 fast drops and subsequent rises in luminosity occurred in time scales of days. We proposed an explanation in which a region moving along the relativistic jet is eclipsed by broad line region clouds or star clusters in the host galaxy. We compare our light curves with contemporaneous X-ray observations from All-Sky Monitor/RXTE. Correlations between optical and X-ray activity were not found in any of the sources at long time scales. However in PKS 2005-489 possible correlations were observed in 1997 and 1998 at short time scales, with optical variability preceding X-rays by 30 days in 1997 and succeeding them by about 10 days in 1998. The analysis of the SED, using the optical data presented here and BeppoSAX contemporaneous observations obtained from the literature, shows only small shifts in the synchrotron peak as the X-ray flux density changes.Comment: 23 pages,12 figures, accepted for publication in A

Double-plating of ovine critical sized defects of the tibia: a low morbidity model enabling continuous in vivo monitoring of bone healing

<p>Abstract</p> <p>Background</p> <p>Recent studies using sheep critical sized defect models to test tissue engineered products report high morbidity and complications rates. This study evaluates a large bone defect model in the sheep tibia, stabilized with two, a novel Carbon fibre Poly-ether-ether-ketone (CF-PEEK) and a locking compression plate (LCP) which could sustain duration for up to 6 month with an acceptable low complication rate.</p> <p>Methods</p> <p>A large bone defect of 3 cm was performed in the mid diaphysis of the right tibia in 33 sheep. The defect was stabilised with the CF - PEEK plate and an LCP. All sheep were supported with slings for 8 weeks after surgery. The study was carried out for 3 months in 6 and for 6 months in 27 animals.</p> <p>Results</p> <p>The surgical procedure could easily be performed in all sheep and continuous in vivo radiographic evaluation of the defect was possible. This long bone critical sized defect model shows with 6.1% a low rate of complications compared with numbers mentioned in the literature.</p> <p>Conclusions</p> <p>This experimental animal model could serve as a standard model in comparative research. A well defined standard model would reduce the number of experimental animals needed in future studies and would therefore add to ethical considerations.</p

Is there a role of coral bone substitutes in bone repair?

Xenogeneic bone graft materials are an alternative to autologous bone grafting. Among such implants, coralline-derived bone grafts substitutes have a long track record as safe, biocompatible and osteoconductive graft materials. In this review, we present the available literature surrounding their use with special focus on the commercially available graft materials. Corals thanks to their chemical and structural characteristics similar to those of the human cancellous bone have shown great potential but clinical data presented to date is ambiguous with both positive and negative outcomes reported. Correct formulation and design of the graft to ensure adequate osteo-activity and resorption appears intrinsic to a successful outcome

Évaluation clinique et biologique d'un ligament synthétique bioactif chez la brebis

1 - ArticleRésumé Le ligament croisé antérieur, qui joue un rôle majeur dans la stabilisation du genou, est le plus fréquemment rompu. Si la greffe autologue est la " technique " la plus utilisée, l'utilisation d'un ligament synthétique est réservée à des applications très précises. Le poly(éthylène téréphtalate) (PET) est le polymère de choix pour élaborer les prothèses ligamentaires mais sa biocompatibilité doit être améliorée. Le greffage du PET par un polymère bioactif poly(styrène sulfonate de sodium) (pNaSS) selon la technique du grafting from permet d'obtenir un taux de greffage parfaitement reproductible de l'ordre de 5 [mu]mol/g. Un groupe de sept brebis ont été implantées des ligaments non greffés alors qu'un second groupe de sept brebis ont été implantées des ligaments greffés du pNaSS pour une durée de trois mois. L'évaluation clinique et biologique du liquide synovial in vivo chez des brebis implantées avec un ligament en PET greffé ou non de pNaSS met en évidence une récupération fonctionnelle précoce et une excellente tolérance du pNaSS se traduisant par une absence d'inflammation articulaire significative. The anterior cruciate ligament, which plays a key role in the knee stabilization, is commonly injured mainly during sport practicing such as soccer or skiing. Although it seems that ligament replacement by a tendon autograft is a better solution, the reconstruction with an artificial ligament provides a shorter recovery time. Polyethylene terephthalate (PET) is the best polymer to fabricate ligament prosthesis but its biocompatibility still needs to be improved. Radical graft polymerization of sodium salt of styrene sulfonate (NaSS) on PET surface was performed using the "grafting from" technique. The grafting ratio is about 5 [mu]mol/g and found to be perfectly reproducible. Polymer grafted ligaments and non-grafted ligaments were implanted in sheep for a 3-month observation. The clinical and biological evaluation of the knee synovial liquid of implanted sheep evidenced an early functional recuperation and an excellent tolerance of pNaSS reflecting a significant absence of articular inflammation

Feasibility Study of the Elaboration of a Biodegradable and Bioactive Ligament Made of Poly(ε-caprolactone)-pNaSS Grafted Fibers for the Reconstruction of Anterior Cruciate Ligament: In Vivo Experiment

International audienc

The influence of Bone Morphogenic Protein-2 on the consolidation phase in a distraction osteogenesis model.

We asked whether locally applied recombinant-Bone Morphogenic Protein-2 (rh-BMP-2) with an absorbable Type I collagen sponge (ACS) carrier could enhance the consolidation phase in a callotasis model. We performed unilateral transverse osteotomy of the tibia in 21 immature male rabbits. After a latency period of 7 days, a 3-weeks distraction was begun at a rate of 0.5mm/12h. At the end of the distraction period (Day 28) animals were randomly divided into three groups and underwent a second surgical procedure: 6 rabbits in Group I (Control group; the callus was exposed and nothing was added), 6 rabbits in Group II (ACS group; receiving the absorbable collagen sponge soaked with saline) and 9 rabbits in Group III (rh-BMP-2/ACS group; receiving the ACS soaked with 100μg/kg of rh-BMP-2, Inductos(®), Medtronic). Starting at Day 28 we assessed quantitative and qualitative radiographic parameters as well as densitometric parameters every two weeks (Days 28, 42, 56, 70 and 84). Animals were sacrificed after 8 weeks of consolidation (Day 84). Qualitative radiographic evaluation revealed hypertrophic calluses in the Group III animals. The rh-BMP-2/ACS also influenced the development of the cortex of the calluses as shown by the modified radiographic patterns in Group III when compared to Groups I and II. Densitometric analysis revealed the bone mineral content (BMC) was significantly higher in the rh-BMP-2/ACS treated animals (Group III)

Observation de ligaments artificiels de genou après implantation en MEB à pression variable

1 - ArticleRésuméObjectifs Comparer deux techniques de préparation d'échantillons pour l'observation en microscopie électronique à balayage à pression variable (MEB-PV) afin d'évaluer la colonisation cellulaire et tissulaire de ligaments artificiels explantés.Matériels et méthodes Des ligaments artificiels en PET et PET greffé par un polymère bioactif, le poly(styrène sulfonate de sodium) ont été implantés dans le genou de quatre brebis après section du ligament croisé antérieur (LCA) puis explantés trois mois plus tard. L'évaluation qualitative de la colonisation cellulaire et tissulaire des ligaments artificiels a été réalisée sur des explants séchés (MEB-PV) ou non (MEB-PV-Peltier) au point critique.Résultats et discussion Les deux techniques évaluées ont permis de mettre en évidence des différences dans la bio-intégration des deux types de ligaments étudiés. Seule la technique MEB-VP-Peltier a permis l'obtention d'images d'excellente définition à fort grossissement se montrant à ce titre très intéressante pour l'évaluation qualitative rapide de l'intégration cellulaire et tissulaire des ligaments artificiels.Objectives We carried out a comparative study between two methods to prepare explanted artificial ligaments samples before their observation in the variable pressure scanning electron microscope (VP-SEM).Materials and methods Poly(ethylene terephtalate) (PET) artificial ligaments grafted by a bioactive polymer, the poly(sodium styrene sulfonate) were implanted for three months in the knee of four ewes after section of the anterior cruciate ligament (ACL). The qualitative evaluation of the cellular and tissue colonization of the artificial ligaments was carried out on critical point-dried explants (observed by VP-SEM) or not (observed by VP-SEM-Peltier).Results and discussion The results showed differences in the biointegration of the two types of studied ligaments. Only the MEB-VP-Peltier technique allowed obtaining images of excellent resolution with high magnification. For this reason the MEB-VP-Peltier technique is a promising method for the fast qualitative evaluation of the cellular and tissue integration of the artificial ligaments