REPARATIVE PROCESSES PROMOTION IN SPORT INJURIES WlTH BONE LESIONS

INTRODUCTION- The injuries of bones in maxillofacial region as a result of traumas in sport are not uncommon. Implantation of apatites containing glasscristalmaterials (AGM) in granules has been suggested for promotion of reparative processes and rehabilitation of athletes with bone defects. The aim of the work is comparative study of osteoinductive characteristics of AGM and composite material based on collagen sponge with 80% AGM (CSAGM)."Biositallw (Russia) has been used as AGM, and "Biositacol" (Russia) - as a CSAGM. The experiment was made on 18 rabbits (3 groups). In 1' and 2nd groups the material have been implanted into perforated holes with diameter 2 mni and 5 mm in depth, located in mandible along the alveolar ridge between incisors and posterior teeth. One group was used as a control one (perforated hole has been filled with blood clots).The samples of implanted materials were taken in 3,7 day, 2,4,6,8 weeks after implantation. Osteoinductive characteristics have been investigated by histomorphologic technique according to osteoblast formation rate and site, their maturation into osteocytes which further formed bone trabeculas with bone plates construction. RESULTS-In the control group of animals whose mandible perforations had been allowed to fill with blood clots, histologic examinations showed acute inflammation reactions in the periphery of the bone defects after seven days. After 2-4 weeks the reproduction of fibroblasts and formation of conjuctive tissue in the bone defect were observed. By the sixth week, the jaw bone defect was filled in with well formed mature conjunctive tissue, and by the eighth week isolated bone tissue growths were observed. In the early stage of the experiment, 3-7 days after implantation, acute inflammation with lymphohisteocytic reaction around the AGM granules was recorded. At the same time, by the second week muttinucleated cells of foreign bodies appeared in all test groups. By the forth week, tymphohisteocytic infiltrates disappeared, and the multinucleated cells of foreign bodies had appeared to resolve the AGM granules. Surrounding the AGM granules, a great number of osteocytes had formed young conjunctive tissue which incapsuled almost every granule. By the sixth week, the histological preparations showed the formation of bone tissue in the periphery of the defect. Regenerated bone spicules in the process of mending developed the spongy structure of bone tissue. By the eighth week, the process of osteogenesis around the AGM granules was far advanced everywhere. During the implantation of CSAGM the extensive osteoclastic response at the defect borders was defined by the 3d day. From the 7Ih day to two weeks single osteoblasts appeared and proliferation of immature cells of collagen tissue was noted. By the second week fibroblast net between AGM granules as well as single new-formed collagen fibers and single bone trabeculas at the defect borders appear. During the 4'h week the defect periphery was filled with bone trabeculas with their partial growth towards the centre. By the 6Ih week osteogenesis was marked all over the defect. CONCLUSION-Both AGM and CSAGM implantation promotes reparative processes in bone injuries comparing with the control group. In CSAGM implantation histomorphological pattern of bone tissue elements formation appears in two weeks earlier than in AGM implantation. The difference in direction of reparative processes in bone has been noted: all over the defect in the zone of AGM implantation and at the defect borders in CSAGM implantation

Nanohardness and young's modulus of tooth enamel

The nanomechanical properties and roughness of tooth enamel are investigated

A Study of the Scintillation Induced by Alpha Particles and Gamma Rays in Liquid Xenon in an Electric Field

Scintillation produced in liquid xenon by alpha particles and gamma rays has been studied as a function of applied electric field. For back scattered gamma rays with energy of about 200 keV, the number of scintillation photons was found to decrease by 64+/-2% with increasing field strength. Consequently, the pulse shape discrimination power between alpha particles and gamma rays is found to reduce with increasing field, but remaining non-zero at higher fields.Comment: 15 pages, 12 figures, accepted by Nuclear Instruments and Methods in Physics Research

Measurements of Scintillation Efficiency and Pulse-Shape for Low Energy Recoils in Liquid Xenon

Results of observations of low energy nuclear and electron recoil events in liquid xenon scintillator detectors are given. The relative scintillation efficiency for nuclear recoils is 0.22 +/- 0.01 in the recoil energy range 40 keV - 70 keV. Under the assumption of a single dominant decay component to the scintillation pulse-shape the log-normal mean parameter T0 of the maximum likelihood estimator of the decay time constant for 6 keV < Eee < 30 keV nuclear recoil events is equal to 21.0 ns +/- 0.5 ns. It is observed that for electron recoils T0 rises slowly with energy, having a value ~ 30 ns at Eee ~ 15 keV. Electron and nuclear recoil pulse-shapes are found to be well fitted by single exponential functions although some evidence is found for a double exponential form for the nuclear recoil pulse-shape.Comment: 11 pages, including 5 encapsulated postscript figure

PAMELA, DAMA, INTEGRAL and Signatures of Metastable Excited WIMPs

Models of dark matter with ~ GeV scale force mediators provide attractive explanations of many high energy anomalies, including PAMELA, ATIC, and the WMAP haze. At the same time, by exploiting the ~ MeV scale excited states that are automatically present in such theories, these models naturally explain the DAMA/LIBRA and INTEGRAL signals through the inelastic dark matter (iDM) and exciting dark matter (XDM) scenarios, respectively. Interestingly, with only weak kinetic mixing to hypercharge to mediate decays, the lifetime of excited states with delta < 2 m_e is longer than the age of the universe. The fractional relic abundance of these excited states depends on the temperature of kinetic decoupling, but can be appreciable. There could easily be other mechanisms for rapid decay, but the consequences of such long-lived states are intriguing. We find that CDMS constrains the fractional relic population of ~100 keV states to be <~ 10^-2, for a 1 TeV WIMP with sigma_n = 10^-40 cm^2. Upcoming searches at CDMS, as well as xenon, silicon, and argon targets, can push this limit significantly lower. We also consider the possibility that the DAMA excitation occurs from a metastable state into the XDM state, which decays via e+e- emission, which allows lighter states to explain the INTEGRAL signal due to the small kinetic energies required. Such models yield dramatic signals from down-scattering, with spectra peaking at high energies, sometimes as high as ~1 MeV, well outside the usual search windows. Such signals would be visible at future Ar and Si experiments, and may be visible at Ge and Xe experiments. We also consider other XDM models involving ~ 500 keV metastable states, and find they can allow lighter WIMPs to explain INTEGRAL as well.Comment: 22 pages, 7 figure

Non-Abelian Dark Sectors and Their Collider Signatures

Motivated by the recent proliferation of observed astrophysical anomalies, Arkani-Hamed et al. have proposed a model in which dark matter is charged under a non-abelian "dark" gauge symmetry that is broken at ~ 1 GeV. In this paper, we present a survey of concrete models realizing such a scenario, followed by a largely model-independent study of collider phenomenology relevant to the Tevatron and the LHC. We address some model building issues that are easily surmounted to accommodate the astrophysics. While SUSY is not necessary, we argue that it is theoretically well-motivated because the GeV scale is automatically generated. Specifically, we propose a novel mechanism by which mixed D-terms in the dark sector induce either SUSY breaking or a super-Higgs mechanism precisely at a GeV. Furthermore, we elaborate on the original proposal of Arkani-Hamed et al. in which the dark matter acts as a messenger of gauge mediation to the dark sector. In our collider analysis we present cross-sections for dominant production channels and lifetime estimates for primary decay modes. We find that dark gauge bosons can be produced at the Tevatron and the LHC, either through a process analogous to prompt photon production or through a rare Z decay channel. Dark gauge bosons will decay back to the SM via "lepton jets" which typically contain >2 and as many as 8 leptons, significantly improving their discovery potential. Since SUSY decays from the MSSM will eventually cascade down to these lepton jets, the discovery potential for direct electroweak-ino production may also be improved. Exploiting the unique kinematics, we find that it is possible to reconstruct the mass of the MSSM LSP. We also present decay channels with displaced vertices and multiple leptons with partially correlated impact parameters.Comment: 44 pages, 25 figures, version published in JHE

Results from the First Science Run of the ZEPLIN-III Dark Matter Search Experiment

The ZEPLIN-III experiment in the Palmer Underground Laboratory at Boulby uses a 12kg two-phase xenon time projection chamber to search for the weakly interacting massive particles (WIMPs) that may account for the dark matter of our Galaxy. The detector measures both scintillation and ionisation produced by radiation interacting in the liquid to differentiate between the nuclear recoils expected from WIMPs and the electron recoil background signals down to ~10keV nuclear recoil energy. An analysis of 847kg.days of data acquired between February 27th 2008 and May 20th 2008 has excluded a WIMP-nucleon elastic scattering spin-independent cross-section above 8.1x10(-8)pb at 55GeV/c2 with a 90% confidence limit. It has also demonstrated that the two-phase xenon technique is capable of better discrimination between electron and nuclear recoils at low-energy than previously achieved by other xenon-based experiments.Comment: 12 pages, 17 figure

Dark Matter Spin-Dependent Limits for WIMP Interactions on 19-F by PICASSO

The PICASSO experiment at SNOLAB reports new results for spin-dependent WIMP interactions on $^{19}$F using the superheated droplet technique. A new generation of detectors and new features which enable background discrimination via the rejection of non-particle induced events are described. First results are presented for a subset of two detectors with target masses of $^{19}$F of 65 g and 69 g respectively and a total exposure of 13.75 $\pm$ 0.48 kgd. No dark matter signal was found and for WIMP masses around 24 GeV/c$^2$ new limits have been obtained on the spin-dependent cross section on $^{19}$F of $\sigma_F$ = 13.9 pb (90% C.L.) which can be converted into cross section limits on protons and neutrons of $\sigma_p$ = 0.16 pb and $\sigma_n$ = 2.60 pb respectively (90% C.L). The obtained limits on protons restrict recent interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent interactions.Comment: Revised version, accepted for publication in Phys. Lett. B, 20 pages, 7 figure