Local SiC photoluminescence evidence of non-mutualistic hot spot formation and sub-THz coherent emission from a rectangular Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} mesa

From the photoluminescence of SiC microcrystals uniformly covering a rectangular mesa of the high transition temperature $T_c$ superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$, the local surface temperature $T({\bm r})$ was directly measured during simultaneous sub-THz emission from the $N\sim10^3$ intrinsic Josephson junctions (IJJs) in the mesa. At high bias currents $I$ and low bath temperatures $T_{\rm bath}\lesssim~35$ K, the center of a large elliptical hot spot with $T({\bm r})> T_c$ jumps dramatically with little current-voltage characteristic changes. The hot spot doesn't alter the ubiquitous primary and secondary emission conditions: the ac Josephson relation and the electromagnetic cavity resonance excitation, respectively. Since the intense sub-THz emission was observed for high $T_{\rm bath}\gtrsim~50$ K in the low $I$ bias regime where hot spots are absent, hot spots can not provide the primary mechanisms for increasing the output power, the tunability, or for promoting the synchronization of the $N$ IJJs for the sub-THz emission, but can at best coexist non-mutualistically with the emission. No $T({\bm r})$ standing waves were observed

Geometrical Resonance Conditions for THz Radiation from the Intrinsic Josephson Junctions in Bi2Sr2CaCu2O8+d

Subterahertz radiation emitted from a variety of short rectangular-, square-, and disk-shaped mesas of intrinsic Josephson junctions fabricated from a Bi2Sr2CaCu2O8+d single crystal was studied from the observed I-V characteristics, far-infrared spectra, and spatial radiation patterns. In all cases, the radiation frequency satisfies the conditions both for the ac Josephson effect and for a mesa cavity resonance mode. The integer higher harmonics observed in all spectra imply that the ac Josephson effect plays the dominant role in the novel dual-source radiation mechanism.Comment: 4 pages, 4 figures, accepted for publication in PR

Variation of Heating Efficiency of Magnetically Sheared CHS Plasmas by Polarization Control of 106GHz EC-Wave

To clarify the effect of polarization on electron cyclotron heating (ECH) in magnetized plasmas, experiment controlling the polarization of injected EC-waves is carried out in Compact Helical System (CHS). In the experiment, plasmas are generated and sustained only with 106.4 GHz ECH power. Magnetic field at the magnetic axis is 1.9 T so that the wave frequency is second harmonic. The optimum direction of linear polarization for the shortest time-delay of density start-up from the start of power injection and the optimum direction for the highest electron temperature and plasma stored energy during plasma duration show clear difference. The difference is attributed to the CHS magnetic configuration with strong shear and the plasma volume expansion from magnetic axis to the last closed flux surface

On-Demand Density Correction Using Steady-State Plasmas in the LHD Thomson Scattering

In order to measure reliable electron densities of fusion plasmas by using Thomson scattering system, both accurate absolute calibration and long-term stability in the system are required. Even if slight misalignment of some optics occurs, it may cause large errors in measured densities. We propose a new method to obtain correctionfactors to the errors originated from misalignment by using steady-state plasma discharges. In addition to the datacorrection, realignment of the laser beam can be applied als

Geometrical Resonance Conditions for THz Radiation from the Intrinsic Josephson Junctions in Bi2Sr2CaCu2O8t

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Afatinib Prolongs Survival Compared with Gefitinib in an Epidermal Growth Factor Receptor-Driven Lung Cancer Model

An irreversible ErbB family blocker is expected to inhibit tumors with activating epidermal growth factor receptor (EGFR) mutations more strongly than reversible EGFR tyrosine kinase inhibitors and to overcome acquired resistance to the T790M secondary mutation. Eleven-week-old transgenic mice with Egfr exon 19 deletion mutation were treated with afatinib, gefitinib, or vehicle for 4 weeks. All mice were sacrificed at 15 weeks of age, and the number of superficial left lung tumors with a long axis exceeding 1 mm was counted. The afatinib-treated group had significantly fewer tumors than the vehicle group (P < 0.01) and tended to have fewer tumors than the gefitinib-treated group (P = 0.06). Pathologically, gefitinib-treated mice had clearer, more nodular tumors than afatinib-treated mice. Immunoblotting showed that afatinib suppressed not only pEGFR but also pHER2, and induced apoptosis for longer periods than gefitinib. Subsequently, when each drug was administered 5 days per week until death, afatinib significantly enhanced mouse survival compared with gefitinib (median survival time: 456 days vs. 376.5 days; log-rank test, P < 0.01). Finally, the combination of afatinib with bevacizumab was found to be superior to either drug alone in exon 19 deletion/T790M and L858R/T790M xenograft tumors. Overall, afatinib was more potent than gefitinib in tumors harboring an exon 19 deletion mutation, and the combination of afatinib with bevacizumab efficiently suppressed tumors harboring the T790M secondary mutation

Photon correlation in GaAs self-assembled quantum dots

We report on photon coincidence measurement in a single GaAs self-assembled quantum dot (QD) using a pulsed excitation light source. At low excitation, when a neutral exciton line was present in the photoluminescence (PL) spectrum, we observed nearly perfect single photon emission from an isolated QD at 670 nm wavelength. For higher excitation, multiple PL lines appeared on the spectra, reflecting the formation of exciton complexes. Cross-correlation functions between these lines showed either bunching or antibunching behavior, depending on whether the relevant emission was from a biexciton cascade or a charged exciton recombination.Comment: 5 pages, 3 figure

High-power terahertz electromagnetic wave emission from high-Tc superconducting Bi2Sr2CaCu2O8+δ mesa structures

In this paper, we report intense electromagnetic wave emissions generated by the rectangular mesa structure of intrinsic Josephson junctions with high-Tc superconducting Bi2Sr2CaCu2O8+δ. The radiated power is an order of magnitude stronger than that of the previously observed power of a few μW. Two emission regions, reversible (R-type) and irreversible (IR-type), with comparable intensities can be observed at different I-V curve locations in the same mesa. We find peculiar temperature dependences of the emission power in both the R- and IR-type radiations, suggesting that a non-equilibrium thermodynamic state may be realized through the dc input current. The R-type emission is quite stable, whereas the IR-type emission is rather unstable. Although the emitted frequency for both cases obey the cavity resonance conditions, this sharp contrast in emission stability is indicative of two different states in a multi-stacked intrinsic Josephson junction system

Finite Element Analysis of the Mouse Proximal Ulna in Response to Elbow Loading

Bone is a mechano-sensitive tissue that alters its structure and properties in response to mechanical loading. We have previously shown that application of lateral dynamic loads to a synovial joint, such as the knee and elbow, suppresses degradation of cartilage and prevents bone loss in arthritis and postmenopausal mouse models, respectively. While loading effects on pathophysiology have been reported, mechanical effects on the loaded joint are not fully understood. Because the direction of joint loading is non-axial, not commonly observed in daily activities, strain distributions in the laterally loaded joint are of great interest. Using elbow loading, we herein characterized mechanical responses in the loaded ulna focusing on the distribution of compressive strain. In response to 1-N peak-to-peak loads, which elevate bone mineral density and bone volume in the proximal ulna in vivo, we conducted finite-element analysis and evaluated strain magnitude in three loading conditions. The results revealed that strain of ~ 1000 μstrain (equivalent to 0.1% compression) or above was observed in the limited region near the loading site, indicating that the minimum effective strain for bone formation is smaller with elbow loading than axial loading. Calcein staining indicated that elbow loading increased bone formation in the regions predicted to undergo higher strain