Optical investigation of thermoelectric topological crystalline insulator Pb0.77_{0.77}Sn0.23_{0.23}Se

Pb$_{0.77}$Sn$_{0.23}$Se is a novel alloy of two promising thermoelectric materials PbSe and SnSe that exhibits a temperature dependent band inversion below 300 K. Recent work has shown that this band inversion also coincides with a trivial to nontrivial topological phase transition. To understand how the properties critical to thermoelectric efficiency are affected by the band inversion, we measured the broadband optical response of Pb$_{0.77}$Sn$_{0.23}$Se as a function of temperature. We find clear optical evidence of the band inversion at $160\pm15$ K, and use the extended Drude model to accurately determine a $T^{3/2}$ dependence of the bulk carrier lifetime, associated with electron-acoustic phonon scattering. Due to the high bulk carrier doping level, no discriminating signatures of the topological surface states are found, although their presence cannot be excluded from our data.Comment: 11 pages, 6 figure

Neutrino Anomalies in Gauge Mediated Model with Trilinear R violation

The structure of neutrino masses and mixing resulting from trilinear $R$ violating interactions is studied in the presence of the gauge mediated supersymmetry breaking. Neutrino masses arise in this model at tree level through the RG-induced vacuum expectation values of the sneutrinos and also through direct contribution at 1-loop. The relative importance of these contributions is determined by the values of the strong and weak coupling constants. In case of purely $\lambda'$ couplings, the tree contribution dominates over the 1-loop diagram. In this case, one simultaneously obtains atmospheric neutrino oscillations and quasi-vacuum oscillations of the solar neutrinos if all the \l' couplings are assumed to be of similar magnitudes. If R parity violation arises from the trilinear \l couplings, then the loop induced contribution dominates over the tree level. One cannot simultaneously explain the solar and atmospheric deficit in this case if all the \l couplings are of similar magnitude. This however becomes possible with hierarchical \l and we give a specific example of this.Comment: 26 pages Latex, 2 figures, certain sections rewritten, improved discussion about derivations added. To appear in Physical Review

Knowledge creation in organizations: proposition for a new model

This study has been set against the backdrop of an increasingly changing business world where innovative competencies are recognized to be important for sustained performance and firm survival. Study of innovations, however, point to upfront problems in the lack of satisfactory explanation as how new knowledge is created in the first place. Nonaka and Takeuchi\u27s SECI description as the leading model of knowledge creation in firms has been critiqued to be incomplete and in being specific to the study context that may not fully represent knowledge creation in other cultures. In this respect, the setting of this research in the Indian context provides the view of how firms in other contexts create knowledge. Using the interpretive approach to study emergence of new knowledge, a modified model of knowledge creation was developed by identifying processes of knowledge creation through setting of events longitudinally. The processes of the model (called as the 4E model) have been identified as enactment, experimentation, embedment and enculturation that are set in the background of organizational descriptors in terms of the local community and the activity, in which it is engaged

Miltefosine Resistant Field Isolate From Indian Kala-Azar Patient Shows Similar Phenotype in Experimental Infection

Abstract Emergence of resistance to drugs used to treat the Indian Kala-azar patients makes control strategy shattered. In this bleak situation, Miltefosine (MIL) was introduced to treat mainly antimonial unresponsive cases. Within years, resistance to MIL has been reported. While checking the MIL sensitivity of the recent KA clinical isolates (n = 26), we came across one isolate which showed four times more EC50 for MIL than that of MIL-Sensitive (MIL-S) isolates and considered as putative MIL-Resistant (MIL-R). The expressions of LdMT and LdRos3 genes of this isolate were found down regulated. Th1/Th2 cytokines, ROS and NO, FACS dot plots and mitochondrial trans membrane potential measurement were performed. In vivo hamster model with this MIL-R isolate showed much lesser reduction in liver weight (17.5%) compared to average reduction in liver weight (40.2%) of the animals infected with MIL-S isolates. The splenic and hepatic stamps smears of MIL-R infected hamsters revealed the retention of parasite load of about 51.45%. The splenocytes of these animals failed to proliferate anti leishmanial T-cells and lack of cell mediated immunity hampered recovery. Thus, these phenotypic expressions of experimental model may be considered similar to that of the MIL unresponsive patients. This is first such kind of report

Mass limits of invisibly decaying Higgs particles from the CERN LEP data

In the Majoron models the SU(2) Higgs doublet can decay invisibly into a Majoron pair via its mixing with a singlet. An analysis of the CERN LEP data shows the invisible decay mode to be more visible than the SM decay. For these models, the dominantly doublet Higgs field H is shown to have a mass limit within ±6 GeV of the SM limit irrespective of the model parameters. But the dominantly singlet one S can be arbitrarily light for a sufficiently small mixing angle

Mahanine, A DNA Minor Groove Binding Agent Exerts Cellular Cytotoxicity with Involvement of C‑7-OH and −NH Functional Groups

Mahanine, a carbazole alkaloid is a potent anticancer molecule. To recognize the structure−activity correlation, mahanine was chemically modified. Antiproliferative activity of these derivatives was determined in 19 cancer cell line from seven different origins. Mahanine showed enhanced apoptosis compared to dehydroxy-mahanine-treated cells, indicating significant contribution of the C-7-OH group. O-Methylated-mahanine and N-methylated dehydroxy-mahanine-treated cells exhibited apoptosis only at higher concentrations, suggesting additional contribution of 9-NH group. Using biophysical techniques, we demonstrated that mahanine interacts with DNA through strong association with phosphate backbone compared to otherderivatives but is unable to induce any conformational change in DNA, hence suggestingthe possibility of being a minor groove binder. This was corroborated by molecular modeling and isothermal titration calorimetry studies. Taken together, the results of the current study represent the first evidence of involvement of C-7-OH and 9-NH group of mahanine for its cytotoxicity and its minor groove binding ability with DN