Type-i Optical Emissions In Gesi Quantum Dots

The authors studied the optical emission of GeSi quantum dots under externally applied biaxial stress using samples grown with different temperatures varying from 430 to 700 °C. The optical emission energy of samples grown at low temperatures is rather insensitive to the applied external stress, consistent with the type-II band alignment. However, for samples grown at high temperatures we observed a large blueshift, which suggests type-I alignment. The result implies that recombination strength can be controlled by the growth temperature, which can be useful for optical device applications. © 2007 American Institute of Physics.915Brunner, K., (2002) Rep. Prog. Phys., 65, p. 27Medeiros-Ribeiro, G., Bratkovski, A.M., Kamins, T.I., Ohlbert, D.A.A., Williams, R.S., (1998) Science, 279, p. 353Wan, J., Jin, G.L., Jiang, Z.M., Luo, Y.H., Liu, J.L., Wang, K.L., (2001) Appl. Phys. Lett., 78, p. 1763El Kurdi, M., Sauvage, S., Fishman, G., Boucaud, P., (2006) Phys. Rev. B, 73, p. 195327Yakimov, A.I., Dvurechenskii, A.V., Nikiforov, A.I., Bloshkin, A.A., Nenashev, A.V., Volodin, V.A., (2006) Phys. Rev. B, 73, p. 115333Dashiell, M.W., Denker, U., Müller, C., Costantini, G., Manzano, C., Kern, K., Schmidt, O.G., (2002) Appl. Phys. Lett., 80, p. 1279Larsson, M., Elfving, A., Holtz, P.O., Hansson, G.V., Ni, W.-X., (2003) Appl. Phys. Lett., 82, p. 4785Thewalt, M.L.W., Harrison, D.A., Reinhart, C.F., Wolk, J.A., Lafontaine, H., (1997) Phys. Rev. Lett., 79, p. 269Larsson, M., Elfving, A., Ni, W.-X., Hansson, G.V., Holtz, P.O., (2006) Phys. Rev. B, 73, p. 195319Schmidt, O.G., Eberl, K., (2000) Phys. Rev. B, 62, p. 16715Tudury, H.A.P., Nakaema, M.K.K., Iikawa, F., Brum, J.A., Ribeiro, E., Carvalho Jr., W., Bernussi, A.A., Gobbi, A.L., (2001) Phys. Rev. B, 64, p. 153301Gomes, P.F., Godoy, M.P.F., Nakaema, M.K.K., Iikawa, F., Lamas, T.E., Quivy, A.A., Brum, J.A., (2004) Phys. Status Solidi C, 3, p. 547De Godoy, M.P.F., Nakaema, M.K.K., Iikawa, F., Carvalho Jr. Wilson, Evaldo, R., Gobbi, A.L., (2004) Rev. Sci. Instrum., 75, p. 194

Low Energy Chiral Lagrangian in Curved Space-Time from the Spectral Quark Model

We analyze the recently proposed Spectral Quark Model in the light of Chiral Perturbation Theory in curved space-time. In particular, we calculate the chiral coefficients $L_1, ..., L_{10}$, as well as the coefficients $L_{11}$, $L_{12}$, and $L_{13}$, appearing when the model is coupled to gravity. The analysis is carried for the SU(3) case. We analyze the pattern of chiral symmetry breaking as well as elaborate on the fulfillment of anomalies. Matching the model results to resonance meson exchange yields the relation between the masses of the scalar, tensor and vector mesons, $M_{f_0}=M_{f_2}=\sqrt{2} M_V= 4 \sqrt{3 /N_c} \pi f_\pi$. Finally, the large-$N_c$ limit suggests the dual relations in the vector and scalar channels, $M_V=M_S= 2 \sqrt{6 /N_c} \pi f_\pi$ and $^{1/2}_S = < r^2 >^{1/2}_V = 2 \sqrt{N_c} / f_\pi = 0.59 {\rm fm}$.Comment: 18 pages, no figure

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Noncommutative Fluids

We review the connection between noncommutative gauge theory, matrix models and fluid mechanical systems. The noncommutative Chern-Simons description of the quantum Hall effect and bosonization of collective fermion states are used as specific examples.Comment: To appear in "Seminaire Poincare X", Institut Henri Poincare, Paris; references adde

Combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma

Results The median progression-free survival was 9.3 months in the dabrafenib-trametinib group and 8.8 months in the dabrafenib-only group (hazard ratio for progression or death in the dabrafenib-trametinib group, 0.75; 95% confidence interval [CI], 0.57 to 0.99; P = 0.03). The overall response rate was 67% in the dabrafenib-trametinib group and 51% in the dabrafenib-only group (P = 0.002). At 6 months, the interim overall survival rate was 93% with dabrafenib-trametinib and 85% with dabrafenib alone (hazard ratio for death, 0.63; 95% CI, 0.42 to 0.94; P = 0.02). However, a specified efficacy-stopping boundary (two-sided P = 0.00028) was not crossed. Rates of adverse events were similar in the two groups, although more dose modifications occurred in the dabrafenib-trametinib group. The rate of cutaneous squamous-cell carcinoma was lower in the dabrafenib-trametinib group than in the dabrafenib-only group (2% vs. 9%), whereas pyrexia occurred in more patients (51% vs. 28%) and was more often severe (grade 3, 6% vs. 2%) in the dabrafenib- trametinib group. Conclusions A combination of dabrafenib and trametinib, as compared with dabrafenib alone, improved the rate of progression-free survival in previously untreated patients who had metastatic melanoma with BRAF V600E or V600K mutations.Background Combined BRAF and MEK inhibition, as compared with BRAF inhibition alone, delays the emergence of resistance and reduces toxic effects in patients who have melanoma with BRAF V600E or V600K mutations.Methods In this phase 3 trial, we randomly assigned 423 previously untreated patients who had unresectable stage IIIC or stage IV melanoma with a BRAF V600E or V600K mutation to receive a combination of dabrafenib (150 mg orally twice daily) and trametinib (2 mg orally once daily) or dabrafenib and placebo. The primary end point was progression-free survival. Secondary end points included overall survival, response rate, response duration, and safety. A preplanned interim overall survival analysis was conducted

Vascular Remodeling in Health and Disease

The term vascular remodeling is commonly used to define the structural changes in blood vessel geometry that occur in response to long-term physiologic alterations in blood flow or in response to vessel wall injury brought about by trauma or underlying cardiovascular diseases.1, 2, 3, 4 The process of remodeling, which begins as an adaptive response to long-term hemodynamic alterations such as elevated shear stress or increased intravascular pressure, may eventually become maladaptive, leading to impaired vascular function. The vascular endothelium, owing to its location lining the lumen of blood vessels, plays a pivotal role in regulation of all aspects of vascular function and homeostasis.5 Thus, not surprisingly, endothelial dysfunction has been recognized as the harbinger of all major cardiovascular diseases such as hypertension, atherosclerosis, and diabetes.6, 7, 8 The endothelium elaborates a variety of substances that influence vascular tone and protect the vessel wall against inflammatory cell adhesion, thrombus formation, and vascular cell proliferation.8, 9, 10 Among the primary biologic mediators emanating from the endothelium is nitric oxide (NO) and the arachidonic acid metabolite prostacyclin [prostaglandin I2 (PGI2)], which exert powerful vasodilatory, antiadhesive, and antiproliferative effects in the vessel wall