Current-induced phase transition in ballistic Ni nanocontacts

Local phase transition from ferromagnetic to paramagnetic state in the region of the ballistic Ni nanocontacts (NCs) has been experimentally observed. We found that contact size reduction leads to an increase in the bias voltage at which the local phase transition occurs. Presented theoretical interpretation of this phenomena takes into the account the specificity of the local heating of the ballistic NC and describes the electron's energy relaxation dependences on the applied voltage. The experimental data are in good qualitative and quantitative agreement with the theory proposed.Comment: 8 pages, 2 figure

GG-Strands

A $G$-strand is a map $g(t,{s}):\,\mathbb{R}\times\mathbb{R}\to G$ for a Lie group $G$ that follows from Hamilton's principle for a certain class of $G$-invariant Lagrangians. The SO(3)-strand is the $G$-strand version of the rigid body equation and it may be regarded physically as a continuous spin chain. Here, $SO(3)_K$-strand dynamics for ellipsoidal rotations is derived as an Euler-Poincar\'e system for a certain class of variations and recast as a Lie-Poisson system for coadjoint flow with the same Hamiltonian structure as for a perfect complex fluid. For a special Hamiltonian, the $SO(3)_K$-strand is mapped into a completely integrable generalization of the classical chiral model for the SO(3)-strand. Analogous results are obtained for the $Sp(2)$-strand. The $Sp(2)$-strand is the $G$-strand version of the $Sp(2)$ Bloch-Iserles ordinary differential equation, whose solutions exhibit dynamical sorting. Numerical solutions show nonlinear interactions of coherent wave-like solutions in both cases. ${\rm Diff}(\mathbb{R})$-strand equations on the diffeomorphism group $G={\rm Diff}(\mathbb{R})$ are also introduced and shown to admit solutions with singular support (e.g., peakons).Comment: 35 pages, 5 figures, 3rd version. To appear in J Nonlin Sc

Application of a mustard root bioassy to assess phytotoxicity of Group 2 herbicides

Non-Peer ReviewedGroup 2 herbicides exhibit high bioactivity at low concentrations in soil and may persist into the next growing season causing crop injury. A bioassay that is suitable for the detection of a range of Group 2 herbicides was developed; in this bioassay, a root growth inhibition of oriental mustard is used for the determination of the herbicide concentration in soil. The Group 2 herbicides included were: Everest (flucarbazone-sodium), Frontline (florasulam), Sundance (sulfosulfuron), and Odyssey (imazamox + imazethapyr). This bioassay was used to examine the degree of root inhibition by simultaneous application of two Group 2 herbicides. Application of varying levels of flucarbazone or sulfosulfuron combined with Odyssey resulted in root length inhibition that was comparable to the root length inhibition caused by application of flucarbazone alone or sulfosulfuron alone and Odyssey alone, possibly indicating an additive effect of these pairs of herbicides. Further studies are needed to examine which combinations of Group 2 herbicides under what environmental and soil conditions may result in “stacking” causing increased plant injury

Coupling of nitrogen-vacancy centers in diamond to a GaP waveguide

The optical coupling of guided modes in a GaP waveguide to nitrogen-vacancy (NV) centers in diamond is demonstrated. The electric field penetration into diamond and the loss of the guided mode are measured. The results indicate that the GaP-diamond system could be useful for realizing coupled microcavity-NV devices for quantum information processing in diamond.Comment: 4 pages 4 figure

Impact of in-crop and soil residual herbicides on effective nitrogen fixation in field pea (Pisum sativum L.) and chickpea (Cicer arietinum L.)

Non-Peer ReviewedA three-year project was initiated in 2004 to examine the effects of residual herbicides and registered “in-crop” herbicides, both soil and foliar applied, on N fixation and consequent yield of field peas and chickpeas. Inoculation strategies were examined to determine if inoculant formulation (i.e., peat powder versus granular inoculant) influences the degree to which herbicides can affect N fixation. This research is ongoing and thus all results are considered preliminary. Preliminary results in field pea, suggest that where herbicides had a negative effect on N fixation, the effects occurred at relatively early growth stages (i.e., soon after herbicide application) and were typically overcome at later growth stages. In addition, granular inoculants were associated with increased N fixation as compared to peat powder inoculants, and may have mitigated any negative herbicide effects. Chickpea incurred damage from the herbicides and all treatments had significantly less N fixation than the control. In general, results suggest that N fixation may be compromised if herbicides cause significant plant damage; however, improved weed control associated with herbicide application may counter the negative impact on early N fixation

In-flight absolute radiometric calibration of the thematic mapper

In order to determine temporal changes of the absolute radiometric calibration of the entire TM system in flight spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM image collections over the White Sands, New Mexico area. By entering the measured values in an atmospheric radiative transfer program, the radiance levels in four of the spectral bands of the TM were determined, band 1:0.45 to 0.52 micrometers, band 2:0.53 to 0.61 micrometers band 3:0.62 to 0.70 micrometers and 4:0.78 to 0.91 micrometers. These levels were compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors

In-flight absolute radiometric calibration of the thematic mapper

The TM multispectral scanner system was calibrated in an absolute manner before launch. To determine the temporal changes of the absolute radiometric calibration of the entire system, spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM collections over White Sands, New Mexico. By entering the measured values in an atmospheric radiative transfer program, the radiance levels of the in four of the spectral bands of the TM were determined. Tables show values for the reflectance of snow at White Sands measured by a modular 8 channel radiometer, and values for exoatmospheric irradiance within the TM passbands, calculated for the Earth-Sun distance using a solar radiometer

Inertial Range Scaling, Karman-Howarth Theorem and Intermittency for Forced and Decaying Lagrangian Averaged MHD in 2D

We present an extension of the Karman-Howarth theorem to the Lagrangian averaged magnetohydrodynamic (LAMHD-alpha) equations. The scaling laws resulting as a corollary of this theorem are studied in numerical simulations, as well as the scaling of the longitudinal structure function exponents indicative of intermittency. Numerical simulations for a magnetic Prandtl number equal to unity are presented both for freely decaying and for forced two dimensional MHD turbulence, solving directly the MHD equations, and employing the LAMHD-alpha equations at 1/2 and 1/4 resolution. Linear scaling of the third-order structure function with length is observed. The LAMHD-alpha equations also capture the anomalous scaling of the longitudinal structure function exponents up to order 8.Comment: 34 pages, 7 figures author institution addresses added magnetic Prandtl number stated clearl

Ballistic and Diffuse Electron Transport in Nanocontacts of Magnetics

The transition from the ballistic electron transport to the diffuse one is experimentally observed in the study of the magnetic phase transition in Ni nanocontacts with different sizes. It is shown that the voltage $U_C$ needed for Joule heating of the near-contact region to the critical temperature does not depend on the contact size only in the diffuse mode. For the ballistic contact it increases with decrease in the nanocontact size. The reduction of the transport electron mean free path due to heating of NCs may result in change of the electron transport mode from ballistic to diffusive one.Comment: 7 pages, 2 figures accepted for the publication in JETPL (http://www.jetpletters.ac.ru). Will be published on 25 april 201