Phase transitions in Lu2_2Ir3_3Si5_5

We report the results of our investigations on a polycrystalline sample of Lu$_2$Ir$_3$Si$_5$ which crystallizes in the U$_2$Co$_3$Si$_5$ type structure (Ibam). These investigations comprise powder X-ray diffraction, magnetic susceptibility, electrical resistivity and high temperature (120-300 K) heat capacity studies. Our results reveal that the sample undergoes a superconducting transition below 3.5 K. It also undergoes a first order phase transition between 150-250 K as revealed by an upturn in the resistivity, a diasmagnetic drop in the magnetic susceptibility and a large anomaly (20-30 J/mol K) in the specific heat data. We observe a huge thermal hysteresis of almost 45 K between the cooling and warming data across this high temperature transition in all our measurements. Low temperature X-ray diffraction measurements at 87 K reveals that the compound undergoes a structural change at the high temperature transition. Resistivity data taken in repeated cooling and warming cycles indicate that at the high temperature transition, the system goes into a highly metastable state and successive heating/cooling curves are found to lie above the previous one and the resistance keeps increasing with every thermal cycle. The room temperature resistance of a thermaly cycled piece of the sample decays exponentialy with time with a decay time constant estimated to be about 10$^4$ secs. The anomaly (upturn) in the resistivity and the large drop (almost 45%) in the susceptibility across the high temperature transition suggest that the observed structural change is accompanied or induced by an electronic transition.Comment: 7 figures, 1 table and 18 reference

Uplift of Himalaya and it’s implications on the evolution of Indian monsoon

Abstract HKT-ISTP 2013 A

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

Theoretical prediction and experimental study of a ferromagnetic shape memory alloy: Ga_2MnNi

We predict the existence of a new ferromagnetic shape memory alloy Ga_2MnNi using density functional theory. The martensitic start temperature (T_M) is found to be approximately proportional to the stabilization energy of the martensitic phase (deltaE_tot) for different shape memory alloys. Experimental studies performed to verify the theoretical results show that Ga_2MnNi is ferromagnetic at room temperature and the T_M and T_C are 780K and 330K, respectively. Both from theory and experiment, the martensitic transition is found to be volume conserving that is indicative of shape memory behavior.Comment: 11 pages, 3 figure

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

Morphological, cultural and pathogenic variability in Alternaria brassicae, the causing agent of black spot of rapeseed and mustard

The study on pathogenic diversity of twenty isolates of Alternaria brassicae collected from different locations of Uttarakhand and Central Uttar Pradesh infecting Brassica species (Brassica rapa, Brassica juncea and Eruca sativa) revealed that there was a distinct difference among isolates in terms of mycelial growth, spore length, width, spore beak length and width. The average spore length varied from 21.23?m to 38.13?m with minimum of isolate AUA-19, AUA-43 i.e 21.23?m and maximum of AUA-47 i.e. 38.13?m . The isolates tested on Brassica juncea var.Varuna in green house conditions revealed that all the twenty isolates behaved differently. Among all the isolates, Brassica juncea isolates i.e. AUA-25, AUA-39, AUA-41, AUA-47, AUA-19, AUA-24, AUA-22, AUA-21, AUA-31, AUA-43 and AUA-45 from Uttarakhand, and AUP-29 from Central Uttar Pradesh can be grouped into highly pathogenic with range of Alternaria spot size i.e. 5.03-8.30mm in diameter, while isolate of Eruca sativa i.e. AUA-38 was found least pathogenic with 1.63mm in dia. and eight isolates AUA-18, AUA-20, AUA-23, AUP-28, AUA-32, AUA-33 and AUA-36 were found moderately pathogenic. This study will be useful in developing integrated management strategies of Alternaria leaf spot and breeding programs of oilseed crops (Brassica sp.)

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

Anti-Inflammatory Activity of Calotropis gigantea and Tridax procumbens on Carrageenin-Induced Paw Edema in Rats

The anti-inflammatory activities of extract of Calotropis gigantea R.Br. and Tridax procumbens Linn., were assessed on carrageenin-induced paw edema along with standard drug, Ibuprofen. The Ibuprofen significantly reduced paw edema at the dose of 200mg/Kg bw orally. The oral administration equi-effective dose (ED50) of C. gigantea (600mg/Kg bw) and T. procumbens (400 mg/Kg bw) individually revealed about 20-35% more activity than the one rendered by administration of 50mg/Kg bw of Ibuprofen. The effect of C. gigantea and T. procumbens along with various dose regimen of Ibuprofen showed greater anti-inflammatory activities than the Ibuprofen alone

Multi-wavelength Diagnostics of the Precursor and Main phases of an M1.8 Flare on 2011 April 22

We study the temporal, spatial and spectral evolution of the M1.8 flare, which occurred in NOAA AR 11195 (S17E31) on 22 April 2011, and explore the underlying physical processes during the precursors and their relation to the main phase. The study of the source morphology using the composite images in 131 {\deg}A wavelength observed by the SDO/AIA and 6-14 keV revealed a multiloop system that destabilized systematically during the precursor and main phases. In contrast, HXR emission (20-50 keV) was absent during the precursor phase, appearing only from the onset of the impulsive phase in the form of foot-points of emitting loop/s. This study has also revealed the heated loop-top prior to the loop emission, although no accompanying foot-point sources were observed during the precursor phase. We estimate the flare plasma parameters viz. T, EM, power-law index, and photon turn-over energy by forward fitting RHESSI spectral observations. The energy released in the precursor phase was thermal and constituted ~1 per cent of the total energy released during the flare. The study of morphological evolution of the filament in conjunction with synthesized T and EM maps has been carried out which reveals (a) Partial filament eruption prior to the onset of the precursor emission, (b) Heated dense plasma over the polarity inversion line and in the vicinity of the slowly rising filament during the precursor phase. Based on the implications from multi-wavelength observations, we propose a scheme to unify the energy release during the precursor and main phase emissions in which, the precursor phase emission has been originated via conduction front formed due to the partial filament eruption. Next, the heated leftover S-shaped filament has undergone slow rise and heating due to magnetic reconnection and finally erupted to produce emission during the impulsive and gradual phases.Comment: 16 Pages, 11 Figures, Accepted for Publication in MNRAS Main Journa

Flavor Ratios of Astrophysical Neutrinos: Implications for Precision Measurements

We discuss flavor-mixing probabilities and flavor ratios of high energy astrophysical neutrinos. In the first part of this paper, we expand the neutrino flavor-fluxes in terms of the small parameters U_{e3} and pi/4 - theta_{23}, and show that there are universal first and second order corrections. The second order term can exceed the first order term, and so should be included in any analytic study. We also investigate the probabilities and ratios after a further expansion around the tribimaximal value of sin^2 theta_{12} = 1/3. In the second part of the paper, we discuss implications of deviations of initial flavor ratios from the usually assumed, idealized flavor compositions for pion, muon-damped, and neutron beam sources, viz., (1 : 2 : 0), (0 : 1 : 0), and (1 : 0 : 0), respectively. We show that even small deviations have significant consequences for the observed flavor ratios at Earth. If initial flavor deviations are not taken into account in analyses, then false inferences for the values in the PMNS matrix elements (angles and phase) may result.Comment: 32 pages, 15 figures. Minor changes, matches version in JHE