Elastic Constants And Structural Parameters Of Selected Polycrystalline Ceramics By Ultrasonic Technique

The present work is an attempt to probe the elastic properties in some dielectric ceramics, by using ultrasonic pulse echo overlap technique. The base Ba6-xSm8+2xTi18O54 and Ca5Nb2TiO12 are very important dielectrics ceramics used for microwave communication as well as for substrate materials. Ultrasonic is one of the most widely used and powerful techniques to measure elastic properties of solids. The ultrasonic technique is nondestructive in nature and the measurements are relatively straightforward to perform. One unique advantantage of the ultrasonic technique is that both static and dynamic properties can be measured simultaneously. The velocity and attenuation coefficients of the ultrasonic waves propagating through a medium are related to the microscopic structure of the material and they provide valuable information about the structural changes in the system. Among the various ultrasonic techniques, the pulse echo overlap method is the most accurate and precise one. In the present case the decreased elastic properties of Cas-XMg,Nb2TiO12 and Cas-,ZnNb2TiO12 ceramics can be attributed to their mixture phases beyond x = 1. Moreover, the abrupt change in elastic properties observed for x >1 can also be correlated to the structural transformation of the materials from their phase pure form to mixture phases for higher extent of substitution of the concerned material . Ca4(ANb2Ti)012 (A = Mg, Zn) is the strongest compound with the maximum values for elastic properties . This could be due to the possible substitution of Mg/Zn ions with lesser radius [25] than Ca2+ in perovskite B-site of Ca(Cali4Nb2i4Tili4) O3 material to contribute more ordering and symmetry to the system [20]. All other compositions (x > 1) contain mixed-phases and for such mixed-phase samples, the mechanical properties are difficult to explain.

Proportionality of sanctions under the WADA Code : CAS jurisprudence and the need for a strict approach

This article suggests that the issue of proportionality in anti-doping sanctions has been inconsistently dealt with by the Court of Arbitration for Sport (CAS). Given CAS’s pre-eminent role in interpreting and applying the World Anti-Doping Code under the anti-doping policies of its signatories, an inconsistent approach to the application of the proportionality principle will cause difficulties for domestic anti-doping tribunals seeking guidance as to the appropriateness of their doping sanctions.

Serotonin Transporter Gene Polymorphism and Myocardial Infarction - Etude Cas-te'moins de L'Infarctus du Myocarde (ECTIM)

Background— Depression is a risk factor for myocardial infarction (MI). Selective serotonin reuptake inhibitors reduce this risk. The site of action is the serotonin transporter (SLC6A4), which is expressed in brain and blood cells. A functional polymorphism in the promoter region of the SLC6A4 gene has been described. This polymorphism may be associated with the risk of MI. Methods and Results— The SLC6A4 polymorphism has been investigated by polymerase chain reaction in 671 male patients with MI and in 688 controls from the Etude Cas-Témoins de l’Infarctus du Myocarde (ECTIM) multicentric study. Percentages for LL, LS, and SS genotypes were 35.5%, 45.4%, and 19.1%, respectively, for cases versus 28.1%, 49.1%, and 22.8%, respectively, for controls. S allele frequency was 41.8% and 47.4% for cases and controls, respectively. After adjustment for age and center by using multivariable logistic regression, the odds ratio for MI associated with the LL genotype was 1.40 (95% CI 1.11 to 1.76, P=0.0047). Conclusions— The LL genotype of the SLC6A4 polymorphism is associated with a higher risk of MI. This could be attributable to the effect of the polymorphism on serotonin-mediated platelet activation or smooth muscle cell proliferation or on other risk factors, such as depression or response to stress

ULTRACAM photometry of the eclipsing cataclysmic variables GY Cnc, IR Com and HT Cas

We present high-speed, three-colour photometry of the eclipsing cataclysmic variables GY Cnc, IR Com and HT Cas. We find that the sharp eclipses in GY Cnc and IR Com are due to eclipses of the white dwarf. There is some evidence for a bright-spot on the edge of the accretion disc in GY Cnc, but not in IR Com. Eclipse mapping of HT Cas is presented which shows changes in the structure of the quiescent accretion disc. Observations in 2002 show the accretion disc to be invisible except for the presence of a bright-spot at the disc edge. 2003 observations, however, clearly show a bright inner disc and the bright-spot to be much fainter than in 2002. Although no outburst was associated with either set of quiescent observations, the system was similar to 0.6 mJy brighter in 2003, mainly due to the enhanced emission from the inner disc. We propose that these changes are due to variations in the mass-transfer rate from the secondary star and through the disc. The disc colours indicate that it is optically thin in both its inner and outer regions. We estimate the white dwarf temperature of HT Cas to be 15 000 +/- 1000 K in 2002 and 14 000 +/- 1000 K in 2003.

Regulation of c-SRC activity and function by the adapter protein CAS

SRC family kinases play essential roles in a variety of cellular functions, including proliferation, survival, differentiation, and apoptosis. The activities of these kinases are regulated by intramolecular interactions and by heterologous binding partners that modulate the transition between active and inactive structural conformations. p130(CAS) (CAS) binds directly to both the SH2 and SH3 domains of c-SRC and therefore has the potential to structurally alter and activate this kinase. In this report, we demonstrate that overexpression of full-length CAS in COS-1 cells induces c-SRC-dependent tyrosine phosphorylation of multiple endogenous cellular proteins. A carboxy-terminal fragment of CAS (CAS-CT), which contains the c-SRC binding site, was sufficient to induce c-SRC-dependent protein tyrosine kinase activity, as measured by tyrosine phosphorylation of cortactin, paxillin, and, to a lesser extent, focal adhesion kinase. A single amino acid substitution located in the binding site for the SRC SH3 domain of CAS-CT disrupted CAS-CT's interaction with c-SRC and inhibited its ability to induce tyrosine phosphorylation of cortactin and paxillin. Murine C3H10T1/2 fibroblasts that expressed elevated levels of tyrosine phosphorylated CAS and c-SRC-CAS complexes exhibited an enhanced ability to form colonies in soft agar and to proliferate in the absence of serum or growth factors. CAS-CT fully substituted for CAS in mediating growth in soft agar but was less effective in promoting serum-independent growth. These data suggest that CAS plays an important role in regulating specific signaling pathways governing cell growth and/or survival, in part through its ability to interact with and modulate the activity of c-SRC.

Excited Electronic States, Transition Probabilities, and Radiative Lifetimes of CAs: A Theoretical Contribution and Challenge to Experimentalists

High-level CASSCF/MRCI calculations with a quintuple-zeta quality basis set are reported by characterizing for the first time a manifold of electronic states of the CAs radical yet to be investigated experimentally. Along with the potential energy curves and the associated spectroscopic constants, the dipole moment functions for selected electronic states as well as the transition dipole moment functions for the most relevant electronic transitions are also presented. Estimates of radiative transition probabilities and lifetimes complement this investigation, which also assesses the effect of spin-orbit interaction on the A (2)Pi state. Whenever pertinent, comparisons of similarities and differences with the isovalent CN and CP radicals are made.