Kelvin-Helmholtz instability of AB interface in superfluid 3He

The Kelvin-Helmholtz instability is well-known in classical hydrodynamics, where it explains the sudden emergence of interfacial surface waves as a function of the velocity of flow parallel to the interface. It can be carried over to the inviscid two-fluid dynamics of superfluids, to study different types of interfaces and phase boundaries in quantum fluids. We report measurements on the stability of the phase boundary separating the two bulk phases of superfluid 3He in rotating flow, while the boundary is localized with the gradient of the magnetic field to a position perpendicular to the rotation axis. The results demonstrate that the classic stability condition, when modified for the superfluid environment, is obeyed down to 0.4 Tc, if a large fraction of the magnetic polarization of the B-phase is attributed to a parabolic reduction of the interfacial surface tension with increasing magnetic field.Comment: 14 pages, 14 figure

Electric fields in plasmas under pulsed currents

Electric fields in a plasma that conducts a high-current pulse are measured as a function of time and space. The experiment is performed using a coaxial configuration, in which a current rising to 160 kA in 100 ns is conducted through a plasma that prefills the region between two coaxial electrodes. The electric field is determined using laser spectroscopy and line-shape analysis. Plasma doping allows for 3D spatially resolved measurements. The measured peak magnitude and propagation velocity of the electric field is found to match those of the Hall electric field, inferred from the magnetic-field front propagation measured previously.Comment: 13 pages, 13 figures, submitted to PR

Corrigendum to "Time-varying magnetotail magnetic flux calculation: a test of the method" published in Ann. Geophys., 27, 1583–1591, 2009

No abstract available

Flux of nutrients from Russian rivers to the Arctic Ocean: Can we establish a baseline against which to judge future changes?

Climate models predict significant warming in the Arctic in the 21st century, which will impact the functioning of terrestrial and aquatic ecosystems as well as alter land‐ocean interactions in the Arctic. Because river discharge and nutrient flux integrate large‐scale processes, they should be sensitive indicators of change, but detection of future changes requires knowledge of current conditions. Our objective in this paper is to evaluate the current state of affairs with respect to estimating nutrient flux to the Arctic Ocean from Russian rivers. To this end we provide estimates of contemporary (1970s–1990s) nitrate, ammonium, and phosphate fluxes to the Arctic Ocean for 15 large Russian rivers. We rely primarily on the extensive data archives of the former Soviet Union and current Russian Federation and compare these values to other estimates and to model predictions. Large discrepancies exist among the various estimates. These uncertainties must be resolved so that the scientific community will have reliable data with which to calibrate Arctic biogeochemical models and so that we will have a baseline against which to judge future changes (either natural or anthropogenic) in the Arctic watershed

Behavioral Barriers of Tuberculosis Notification in Private Health Sector: Policy implication and Practice

Under-reporting of new tuberculosis (TB) cases is one of the main problems in TB control, particularly in countries with high incidence and dominating role of a private sector in TB cases diagnosing. The purpose of this paper was to explore behavioral determinants of under-reporting of new TB cases among private sector physicians in Iran. We conducted a population-based, cross-sectional study of physicians working in private clinics. The data collection tool was designed using the theory of planned behavior. We used structural equation models with maximum likelihood estimation to examine attitude towards the notification behavior. Of 519 physicians, 433 physicians completed the questionnaire. Attitude towards notification had the highest score (mean score=87.65; sd=6.79; range: 0-100). The effect of perceived behavioral controls on the notification behavior ((β ̂)= 0.13; CI: .01-.25) was stronger than the total effect of attitude ((β ̂)=0.06; CI: .00-.12) and subjective norms ((β ̂)=0.01; CI: -.00 -.03) on the behavior. However, the attitude was the main predictor of intention and justified 46% of the intention variance. Intention had a significant effect on the behavior ((β ̂)= 0.09; CI:.01- .16). Considering stronger effect of perceived behavioral control on the behavior, interventions aiming at facilitating notification process would be more effective than those aiming at changing the attitude or enhancing intention among physicians. To the best of our knowledge, no other study previously explored determinants of under-reporting from the behavioral and cognitive perspective. Specifically, we explored the role of the theory of planned behavior constructs in predicting intention to notify new TB cases

Preseismic ULF electromagnetic effect from observation at Kamchatka

International audienceSome results of ULF magnetic field observation at Karimshino site (Kamchatka, Russia) since June 2000 to September 2001 are presented here. Using case study we have found an effect of suppression of ULF intensity about 2?6 days before rather strong and nearby seismic shocks (magnitude M = 4.0 ? 6.2). It is revealed for nighttime and horizontal component of ULF field (G) in the frequency range 0.01 ? 0.1 Hz. Then we prove the reliability of the effect by computed correlation between G (or 1/G) and specially calculated seismic indexes Ks for the whole period of observation. Basing on the simple criteria we conclude that reliability of seismo-associated ULF suppression effect is comparable with well-known effect of connection between ULF variation and Kp index of global magnetic activity. It seems the reason of suppression is located at the atmosphere or ionosphere but not in the ground medium

Contribution of magnetotail reconnection to the cross-polar cap electric potential drop

Since the work of Dungey (1961), the global circulation pattern with two (dayside and nightside) reconnection regions has become a classic concept. However, the contributions of dayside and nightside sources to the cross-polar cap potential (PCP) are not fully understood, particularly, the relative role and specifics of the nightside source are poorly investigated both in quantitative and qualitative terms. To fill this gap, we address the contributions of dayside and nightside sources to the PCP by conducting global MHD simulations with both idealized solar wind input and an observed event input. The dayside source was parameterized by solar wind–based “dayside merging potential” Φd = LeffVBt sin4(θ/2), whereas to characterize the nightside source we integrated across the tail the dawn-dusk electric field in the plasma sheet (to obtain the “cross-tail potential” Φn). For the idealized run we performed simulations using four MHD codes available at the Community Coordinated Modeling Center to show that contribution of the nightside source is a code-independent feature (although there are many differences in the outputs provided by different codes). Particularly, we show that adding a nightside source to the linear fit function for the ionospheric potential (i.e., using the fit function Φfit = KdΦd + KnΦn + Φ0) considerably improves the fitting results both in the idealized events as well as in the simulation of an observed event. According to these simulations the nightside source contribution to the PCP has a fast response time (<5 min) and a modest efficiency (potential transmission factor from tail to the ionosphere is small, Kn < 0.2), which is closely linked to the primarily inductive character of strong electric field generated in the plasma sheet. The latter time intervals are marked by strongly enhanced nightside (lobe) reconnection and can be associated with substorm expansion phases. This association is further strengthened by the simulated patterns of precipitation, the R1-type field-aligned substorm current wedge currents and Hall electrojet currents, which are consistent with the known substorm signatures

Density-shear instability in electron magneto-hydrodynamics

We discuss a novel instability in inertia-less electron magneto-hydrodynamics (EMHD), which arises from a combination of electron velocity shear and electron density gradients. The unstable modes have a lengthscale longer than the transverse density scale, and a growth-rate of the order of the inverse Hall timescale. We suggest that this density-shear instability may be of importance in magnetic reconnection regions on scales smaller than the ion skin depth, and in neutron star crusts. We demonstrate that the so-called Hall drift instability, previously argued to be relevant in neutron star crusts, is a resistive tearing instability rather than an instability of the Hall term itself. We argue that the density-shear instability is of greater significance in neutron stars than the tearing instability, because it generally has a faster growth-rate and is less sensitive to geometry and boundary conditions. We prove that, for uniform electron density, EMHD is "at least as stable" as regular, incompressible MHD, in the sense that any field configuration that is stable in MHD is also stable in EMHD. We present a connection between the density-shear instability in EMHD and the magneto-buoyancy instability in anelastic MHD

ALTERATION OF ACTIVE SUBSTANCE CONTENT IN "HEXACHLORAN DUST" PESTICIDE FORMULATION AT EXPOSURE TO ELECTRON BEAM

The most popular methods of organochlorinated pesticides (OCP) destruction, which are based on thermal dechlorination, are not ecologically safe. The other process – radiation-chemical degradation – has got some advantages. It does not involve high temperatures and expensive reagents. In this study, the effective OCP degradation was observed under irradiation of residuals of the active substance of ‘Hexachloran dust’ pesticide formulation, intended for utilization. Parameters for the preparation powder (dry form) exposure to electron beam are discussed. It is shown that at the exposure to electron beam at dose of 100 kGy, the degradation degree of hexachlorocyclohexane (HCH) isomers in a composition of active substance achieves 56.2–66.3%

Observation of nuclei with energies 8-30 MeV per nucleon in the Earth's magnetosphere at the altitudes 350 KM

Observations of the flux of nuclei with an energy of IO MeV per nucleon on the Salyut-7 Station in September 1984 are presented. The observed flux is smaller by a factor of 50 than the flux detected in May, 1981