Non-linear Microwave Surface Impedance of Epitaxial HTS Thin Films in Low DC Magnetic Fields

We have carried out non-linear microwave (8 GHz) surface impedance measurements of three YBaCuO thin films in dc magnetic fields $H_{dc}$ (parallel to c axis) up to 12 mT using a coplanar resonator technique. In zero dc field the three films, deposited by the same method, show a spread of low-power residual surface resistance, $R_{res}$ and penetration depth, $\lambda$ (T=15 K) within a factor of 1.9. However, they exhibit dramatically different microwave field, $H_{rf}$ dependences of the surface resistance, $R_s$, but universal $X_s(H_{rf})$ dependence. Application of a dc field was found to affect not only absolute values of $R_s$ and $X_s$, but the functional dependences $R_s(H_{rf})$ and $X_s(H_{rf})$ as well. For some of the samples the dc field was found to decrease $R_s$ below its zero-field low-power value.Comment: 4 pages, 4 figures. To be published in IEEE Trans. Appl. Supercond., June 199

Ferromagnetism at 300 K in spin-coated anatasea and rutile Ti0.95Fe0.05O2 films

Thin films of Ti1-xFexO2 (x=0 and 0.05) have been prepared on sapphire substrates by spin-on technique starting from metal organic precursors. When heat treated in air at 550 and 700 degrees C respectively, these films present pure anatase and rutile structures as shown both by X-ray diffraction and Raman spectroscopy. Optical absorption indicate a high degree of transparency in the visible region. Such films show a very small magnetic moment at 300 K. However, when the anatase and the rutile films are annealed in a vacuum of 1x10-5 Torr at 500 degrees C and 600 degrees C respectively, the magnetic moment, at 300 K, is strongly enhanced reaching 0.46 $\mu$B/Fe for the anatase sample and 0.48 $\mu$B/Fe for the rutile one. The ferromagnetic Curie temperature of these samples is above 350 K.Comment: 13 october 200

Quality of Experience Framework for Cloud Computing (QoC)

Cloud computing provides platform for pay per use services such as software (e.g., database, data processing, application servers, etc.), hardware (e.g., GPUs, CPUs, storage, etc.) and platforms (e.g., Linux, Microsoft Windows and Apple macOS). Previous cloud frameworks use fix policies that do not have the functionality to upgrade services on demand when the user do not receive services according to Service Level Agreement (SLA). Also, there was a lack of functionality to monitor external network and client device resources. This paper presents Quality of experience framework for Cloud computing (QoC) for monitoring the Quality of Experience (QoE) of the end user using video streaming services in the cloud computing environment. The management platform is used for administration purpose in QoC framework that provides facility to easily manage the cloud environment and provide services according to SLA via runtime policy change. The objective QoE/QoS section will automatically monitor the Quality of Service (QoS) data. It will also compare and analyze the subjective QoE submitted by the users and objective QoS data collected by agent based framework for accurate QoE prediction and proper management. The proposed QoC framework has new features of real time network monitoring, client device monitoring and allows changing policy in runtime environment which to our knowledge is currently not provided by existing frameworks

Crystal structure, magnetism and magnetocaloric properties of Mn\u3csub\u3e2−x\u3c/sub\u3eSn\u3csub\u3e0.5\u3c/sub\u3eGa\u3csub\u3e0.5\u3c/sub\u3e (x=0, 0.3, 0.5, 0.8) alloys

Magnetic refrigeration based on the magnetocaloric effect has attracted recent attention due to advantages such as high efficiency and environmental friendliness. We have investigated the structural, magnetic and magnetocaloric properties of Mn2−xSn0.5Ga0.5 (x=0, 0.3, 0.5, 0.8) alloys prepared using arc-melting and meltspinning techniques with prospects for magnetic refrigeration. The Mn2−xSn0.5Ga0.5 alloys, except for Mn1.2Sn0.5Ga0.5, have a single-phase hexagonal crystal structure. The Mn1.2Sn0.5Ga0.5 alloy also contains a small amount of MnSn2 impurity phase. The Curie temperature and high-field (30 kOe) magnetization at 55 K decrease with increasing Mn concentration from 306 K and 64.1 emu/g (1.07 μB/Mn) for Mn1.2Sn0.5Ga0.5 to 262 K and 46.7 emu/g (0.85 μB/Mn) for Mn2Sn0.5Ga0.5, respectively. The peak values of magnetic entropy change are relatively small with ΔSM,max=1.7 Jkg−1K−1for Mn1.5Sn0.5Ga0.5 at 30 kOe. Despite this, these materials show considerable relative cooling power (RCP) along with a wide working temperature range near room temperature and negligible magnetic and thermal hysteresis, where Mn1.2Sn0.5Ga0.5 shows a highest RCP of 102.3 Jkg−1 at 30 kOe

Forward Brillouin scattering in hollow-core photonic bandgap fibers

We quantify the strength of stimulated forward Brillouin scattering in hollow-core photonic bandgap fiber through a combination of experiments and multi-physics simulations. Brillouin spectroscopy methods reveal a family of densely spaced Brillouin-active phonon modes below 100 MHz with coupling strengths that approach those of conventional silica fiber. The experimental results are corroborated by multi-physics simulations, revealing that relatively strong optomechanical coupling is mediated by a combination of electrostriction and radiation pressure within the nano-scale silica-air matrix; the nontrivial mechanical properties of this silica-air matrix facilitate the large optomechanical response produced by this system. Simulations also reveal an incredible sensitivity of the Brillouin spectrum to fiber critical dimensions, suggesting opportunity for enhancement or suppression of these interactions. Finally, we relate the measured and calculated couplings to the noise properties of the fiber as the foundation for phase-and polarization-noise estimates in hollow-core fiber. More generally, such Brillouin interactions are an important consideration in both the high and low optical intensity limits.open11115sciescopu

The Risk Factors of Seasonal Hyperacute Panuveitis

Background: Seasonal Hyperacute Panuveitis (SHAPU) is an eye disease of unclear aetiology occurring cyclically during the autumn in odd years in Nepal causing blindness within a week. This study is the first of its type to investigate the risk factors of SHAPU. Methods: A multicentric national level case–control study was performed during the 2017 SHAPU outbreak. Cases were matched to controls in a 1:3 ratio based on age, sex and geographic area. Questionnaire-based personal interview was used and risk factors were categorized as biological and behavioral. For univariate analysis, frequency, median and interquartile range was calculated. Chi-squared test with/without continuity correction and Fisher’s exact test were used. Multivariate conditional logistic regressions were used for all the independent variables for p <0.1 in the univariate analyses. Results: We identified 35 cases and 105 controls; 71.4% were children≤16 years (38-day infant to 50-year-old). All were immunocompetent individuals, males were 57.1% and females 42.9%. Potential risks such as visible moths/butterfly activity, contact with livestock, and attending mass gatherings of people were not reported more frequently in cases vs controls in univariate analyses. Differences in possibly protective factors such as self-reported mosquito net use, light off at night while sleeping, and habit of hands/face washing after physical contact/touch with any insects/butterflies/birds were not statistically significant between both groups. In multivariate model, SHAPU cases were significantly more likely than controls to report physical contact with butterflies/white moths (Adjusted OR:6.89; CI:2.79–17.01,p < .001). Conclusions: Direct physical contact with butterflies/moths was associated with significantly increased odds of SHAPU cases