15 resultados para 63, 22 p.
em Indian Institute of Science - Bangalore - Índia
Resumo:
Four new hybrid (bolaphile/amphiphile) ion-pairs were synthesized. Electron microscopy indicated that each of these forms bilayer membranes upon dispersion in aqueous media. Membrane properties have also been examined by differential scanning calorimetry, microcalorimetry, temperature-dependent fluorescence anisotropy measurements, and UV-vis spectroscopy. The T-m values for the vesicular 1, 2, 3, 4, and 5 were 38, 12, 85, 31.3, and 41.6 degrees C, respectively. Interestingly the T-m values for 1 and 3 were found to depend on their concentration. The entrapment of small solute and the release capability have also been examined to demonstrate that these bilayers form enclosed vesicles. X-ray diffraction of the cast films has been performed to understand the nature and the thickness of these membrane organizations. The membrane widths ranged from 33 to 47 Angstrom. Finally, the above observations have been analyzed in light of the results obtained from molecular modeling studies. Thus we have demonstrated that membrane properties can be modulated by simple structural changes at the amphiphile level. It was shown that by judicious incorporation of central, isomeric, disubstituted aromatic units as structural anchors into different bolaphiles, one can modulate the properties of the resulting vesicles.
Resumo:
Overexpression of the epidermal growth factor receptor family genes, which include ErbB-1, 2, 3 and 4, has been implicated in a number of cancers. We have studied the extent of ErbB-2 overexpression among Indian women with sporadic breast cancer. Methods: Immmunohistochemistry and genomic polymerase chain reaction (PCR) were used to study the ErbB2 overexpression. ErbB2 status was correlated with other clinico-pathological parameters, including patient survival. Results: ErbB-2 overexpression was detected in 43.2% (159/368) of the cases by immunohistochemistry. For a sub-set of patients (n = 55) for whom total DNA was available, ErbB-2 gene amplification was detected in 25.5% (14/55) of the cases by genomic PCR. While the ErbB2 overexpression was significantly higher in patients with lymphnode (2 = 12.06, P 0.001), larger tumor size (2 = 8.22, P = 0.042) and ductal carcinoma (2 = 15.42, P 0.001), it was lower in patients with disease-free survival (2 = 22.13, P 0.001). Survival analysis on a sub-set of patients for whom survival data were available (n = 179) revealed that ErbB-2 status (2 =25.94, P 0.001), lymphnode status (2 = 12.68, P 0.001), distant metastasis (2 = 19.49, P 0.001) and stage of the disease (2 = 28.04, P 0.001) were markers of poor prognosis. Conclusions: ErbB-2 overexpression was significantly greater compared with the Western literature, but comparable to other Indian studies. Significant correlation was found between ErbB-2 status and lymphnode status, tumor size and ductal carcinoma. ErbB-2 status, lymph node status, distant metastasis and stage of the disease were found to be prognostic indicators.
Resumo:
We report results from a first principles calculation of spatially dependent correlation functions around a magnetic impurity in metals described by the nondegenerate Anderson model. Our computations are based on a combination of perturbative scaling theory and numerical renormalization group methods. Results for the conduction election charge density around the impurity and correlation functions involving the conduction electron and impurity charge and spin densities will be presented. The behavior in various regimes including the mixed valent regime will be explored.
Resumo:
Current-voltage (I-V) characteristics of quench condensed, superconducting, ultrathin Bi films in a magnetic field are reported. These I-V's show hysteresis for all films, grown both with and without thin Ge underlayers. Films on Ge underlayers, close to superconductor-insulator transition, show a peak in the critical current, indicating a structural transformation of the vortex solid. These underlayers, used to make the films more homogeneous, are found to be more effective in pinning the vortices. The upper critical fields (B-c2) of these films are determined from the resistive transitions in perpendicular magnetic field. The temperature dependence of the upper critical field is found to differ significantly from Ginzburg-Landau theory, after modifications for disorder.
Resumo:
[1] D. Tse and P. Viswanath, Fundamentals of Wireless Communication.Cambridge University Press, 2006. [2] H. Bolcskei, D. Gesbert, C. B. Papadias, and A.-J. van der Veen, Spacetime Wireless Systems: From Array Processing to MIMO Communications.Cambridge University Press, 2006. [3] Q. H. Spencer, C. B. Peel, A. L. Swindlehurst, and M. Haardt, An introduction to the multiuser MIMO downlink, IEEE Commun. Mag.,vol. 42, pp. 6067, Oct. 2004. [4] K. Kusume, M. Joham,W. Utschick, and G. Bauch, Efficient tomlinsonharashima precoding for spatial multiplexing on flat MIMO channel,in Proc. IEEE ICC2005, May 2005, pp. 20212025. [5] R. Fischer, C. Windpassinger, A. Lampe, and J. Huber, MIMO precoding for decentralized receivers, in Proc. IEEE ISIT2002, 2002, p.496. [6] M. Schubert and H. Boche, Iterative multiuser uplink and downlink beamforming under SINR constraints, IEEE Trans. Signal Process.,vol. 53, pp. 23242334, Jul. 2005. [7] , Solution of multiuser downlink beamforming problem with individual SINR constraints, IEEE Trans. Veh. Technol., vol. 53, pp.1828, Jan. 2004. [8] A. Wiesel, Y. C. Eldar, and Shamai, Linear precoder via conic optimization for fixed MIMO receivers, IEEE Trans. Signal Process., vol. 52,pp. 161176, Jan. 2006. [9] N. Jindal, MIMO broadcast channels with finite rate feed-back, in Proc. IEEE GLOBECOM2005, Nov. 2005. [10] R. Hunger, F. Dietrich, M. Joham, and W. Utschick, Robust transmit zero-forcing filters, in Proc. ITG Workshop on Smart Antennas, Munich,Mar. 2004, pp. 130137. [11] M. B. Shenouda and T. N. Davidson, Linear matrix inequality formulations of robust QoS precoding for broadcast channels, in Proc.CCECE2007, Apr. 2007, pp. 324328. [12] M. Payaro, A. Pascual-Iserte, and M. A. Lagunas, Robust power allocation designs for multiuser and multiantenna downlink communication systems through convex optimization, IEEE J. Sel. Areas Commun.,vol. 25, pp. 13921401, Sep. 2007. [13] M. Biguesh, S. Shahbazpanahi, and A. B. Gershman, Robust downlink power control in wireless cellular systems, EURASIP Jl. Wireless Commun. Networking, vol. 2, pp. 261272, 2004. [14] B. Bandemer, M. Haardt, and S. Visuri, Liner MMSE multi-user MIMO downlink precoding for users with multple antennas, in Proc.PIMRC06, Sep. 2006, pp. 15. [15] J. Zhang, Y. Wu, S. Zhou, and J. Wang, Joint linear transmitter and receiver design for the downlink of multiuser MIMO systems, IEEE Commun. Lett., vol. 9, pp. 991993, Nov. 2005. [16] S. Shi, M. Schubert, and H. Boche, Downlink MMSE transceiver optimization for multiuser MIMO systems: Duality and sum-mse minimization,IEEE Trans. Signal Process., vol. 55, pp. 54365446, Nov.2007. [17] A. Mezghani, M. Joham, R. Hunger, and W. Utschick, Transceiver design for multi-user MIMO systems, in Proc. WSA 2006, Mar. 2006. [18] R. Doostnejad, T. J. Lim, and E. Sousa, Joint precoding and beamforming design for the downlink in a multiuser MIMO system, in Proc.WiMob2005, Aug. 2005, pp. 153159. [19] N. Vucic, H. Boche, and S. Shi, Robust transceiver optimization in downlink multiuser MIMO systems with channel uncertainty, in Proc.IEEE ICC2008, Beijing, China, May 2008. [20] A. Ben-Tal and A. Nemirovsky, Selected topics in robust optimization,Math. Program., vol. 112, pp. 125158, Feb. 2007. [21] D. Bertsimas and M. Sim, Tractable approximations to robust conic optimization problems, Math. Program., vol. 107, pp. 536, Jun. 2006. [22] P. Ubaidulla and A. Chockalingam, Robust Transceiver Design for Multiuser MIMO Downlink, in Proc. IEEE Globecom2008, New Orleans, USA, Dec. 2008, to appear. [23] S. Boyd and L. Vandenberghe, Convex Optimization. Cambridge University Press, 2004. [24] G. H. Golub and C. F. V. Loan, Matrix Computations. The John Hopkins University Press, 1996.
