Spin-lattice coupling mediated giant magnetodielectricity across the spin reorientation in Ca2FeCoO5

The structural, phonon, magnetic, dielectric, and magneto dielectric responses of the pure bulk Brownmillerite compound Ca2FeCoO5 are reported. This compound showed giant magneto dielectric response (10%-24%) induced by strong spin-lattice coupling across its spin reorientation transition (150-250 K). The role of two Debye temperatures pertaining to differently coordinated sites in the dielectric relaxations is established. The positive giant magneto-dielectricity is shown to be a direct consequence of the modulations in the lattice degrees of freedom through applied external field across the spin reorientation transition. Our study illustrates novel control of magneto-dielectricity by tuning the spin reorientation transition in a material that possess strong spin lattice coupling.Comment: 7 pages, 12 figure

Ignorance is Almost Bliss: Near-Optimal Stochastic Matching With Few Queries

The stochastic matching problem deals with finding a maximum matching in a graph whose edges are unknown but can be accessed via queries. This is a special case of stochastic $k$-set packing, where the problem is to find a maximum packing of sets, each of which exists with some probability. In this paper, we provide edge and set query algorithms for these two problems, respectively, that provably achieve some fraction of the omniscient optimal solution. Our main theoretical result for the stochastic matching (i.e., $2$-set packing) problem is the design of an \emph{adaptive} algorithm that queries only a constant number of edges per vertex and achieves a $(1-\epsilon)$ fraction of the omniscient optimal solution, for an arbitrarily small $\epsilon>0$. Moreover, this adaptive algorithm performs the queries in only a constant number of rounds. We complement this result with a \emph{non-adaptive} (i.e., one round of queries) algorithm that achieves a $(0.5 - \epsilon)$ fraction of the omniscient optimum. We also extend both our results to stochastic $k$-set packing by designing an adaptive algorithm that achieves a $(\frac{2}{k} - \epsilon)$ fraction of the omniscient optimal solution, again with only $O(1)$ queries per element. This guarantee is close to the best known polynomial-time approximation ratio of $\frac{3}{k+1} -\epsilon$ for the \emph{deterministic} $k$-set packing problem [Furer and Yu, 2013] We empirically explore the application of (adaptations of) these algorithms to the kidney exchange problem, where patients with end-stage renal failure swap willing but incompatible donors. We show on both generated data and on real data from the first 169 match runs of the UNOS nationwide kidney exchange that even a very small number of non-adaptive edge queries per vertex results in large gains in expected successful matches

Trend Analysis of Annual and Seasonal Rainfall in Tawa command Area

The main objective of the study is to identify the trend in annual rainfall time series data as well as seasonal rainfall time series of four rainy months i.e. June, July, August and September during the period of 1971 to 2015. The annual sessional trend of rainfall was determinedby non-parametric Mann-Kendall test. Also a non-parametric Sen's Slope estimator was used for the determination of magnitude of trend. A functional relationship has been developed between variables using linear regression analysis in order to determine a linear trend of rainfall for the study area. The study concludes considering the result of all statistical test results, that the study area has shown variability in annual sessional rainfall pattern due to climatic variations. Also the sessional trend analysis of rainfall has suggested that there is a trendvariationof rainfall in the rainymonths

Modulated structure in the martensite phase of Ni1.8Pt0.2MnGa: a neutron diffraction study

7M orthorhombic modulated structure in the martensite phase of Ni1.8Pt0.2MnGa is reported by powder neutron diffraction study, which indicates that it is likely to exhibit magnetic field induced strain. The change in the unit cell volume is less than 0.5% between the austenite and martensite phases, as expected for a volume conserving martensite transformation. The magnetic structure analysis shows that the magnetic moment in the martensite phase is higher compared to Ni2MnGa, which is in good agreement with magnetization measurement

Observation of Radially Inward Turbulent Particle Flux in ETG dominated Plasma of LVPD

Radially inward turbulent particle flux is observed in the core region of target plasma of Large Volume Plasma Device(LVPD). The region satisfy conditions for ETG turbulence, i.e. threshold condition, $\eta_e = L_{n_e} / L_{T_e} > 2/3$ , where density scale length, $L_{n_e} \sim 300 cm$ and temerature scale length, $L_{T_e} \sim 50cm$[S.K. Mattoo et al., Phys. Rev. Lett., 108, 255007(2012)\cite{Mattoo_PRL}]. The measured flux is dominantly electrostatic ($\Gamma_{es} \approx 10^{5} \Gamma_{em}$) although the nature of the measured turbulence is electromagnetic($\beta \approx 0.6$). The turbulence has been established as a consequence of electron temperature gradient (ETG) driven modes. Experimental observations of phase angle between density ($n_e$) and potential ($\phi$) fluctuations, $\theta_{\tilde{n}_e, \tilde{\phi}}$ and electrostatic particle flux, $\Gamma_{es}$ shows good agreement with the corresponding theoretical estimates for ETG turbulence.Comment: 11 pages, 18 figure

Quantum Chessboards in the Deuterium Molecular Ion

We present a new algorithm for vibrational control in deuterium molecules that is feasible with current experimental technology. A pump mechanism is used to create a coherent superposition of the D2+ vibrations. A short, intense infrared control pulse is applied after a chosen delay time to create selective interferences. A `chessboard' pattern of states can be realized in which a set of even- or odd-numbered vibrational states can be selectively annihilated or enhanced. A technique is proposed for experimental realization and observation of this effect using 5 fs pulses of 790 nm radiation, with intermediate intensity (5e13 W/cm2)Comment: 12 pages, 5 figure