1,002 research outputs found
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
A commutator description of the solvable radical of a finite group
We are looking for the smallest integer k>1 providing the following characterization of the solvable radical R(G) of any finite group G: R(G) coincides with the collection of all g such that for any k elements a_1,a_2,...,a_k the subgroup generated by the elements g, a_iga_i^{-1}, i=1,...,k, is solvable. We consider a similar problem of finding the smallest integer l>1 with the property that R(G) coincides with the collection of all g such that for any l elements b_1,b_2,...,b_l the subgroup generated by the commutators [g,b_i], i=1,...,l, is solvable. Conjecturally, k=l=3. We prove that both k and l are at most 7. In particular, this means that a finite group G is solvable if and only if in each conjugacy class of G every 8 elements generate a solvable subgroup
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
Corrigendum to "Time-varying magnetotail magnetic flux calculation: a test of the method" published in Ann. Geophys., 27, 1583–1591, 2009
No abstract available
Every Newborn INDEPTH (EN-INDEPTH) Study - Additional Materials
The Every Newborn- International Network for the Demographic Evaluation of Populations and their Health (EN-INDEPTH) study was a cross-sectional, multi-site study conducted between July 2017 and August 2018, including a survey of 69,176 women aged 15-49 years in five Health and Demographic Surveillance Sites (HDSS) within the INDEPTH Network: Bandim in Guinea-Bissau, Dabat in Ethiopia, IgangaMayuge in Uganda, Matlab in Bangladesh and Kintampo in Ghana. The primary objective of the study was to compare two methods of retrospective recording of pregnancy outcomes in surveys: Full Birth History with additional questions on pregnancy losses (FBH+), and Full Pregnancy History (FPH). A secondary objective was to identify barriers and enablers to the reporting of pregnancy and adverse pregnancy outcomes during the survey and HDSS data collection, and particularly if these differ for the two survey questionnaire methods (FBH+ and FPH). The study also evaluated the use of existing/modified survey questions to capture the fertility intentions and selected pregnancy outcomes (Termination of Pregnancy, miscarriage, birthweight, gestational age), and birth and death certification
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 windβbased βdayside merging potentialβ Ξ¦d = LeffVBt sin4(ΞΈ/2), whereas to characterize the nightside source we integrated across the tail the dawn-dusk electric field in the plasma sheet (to obtain the βcross-tail potentialβ Ξ¦n). 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 Ξ¦fit = KdΞ¦d + KnΞ¦n + Ξ¦0) 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
Method Quantitative for Determination of Carbonate Ions in Layered Rare-Earth Hydroxides by X-Ray Fluoriscence Spectrometry
Π‘Π»ΠΎΠΈΡΡΡΠ΅ Π³ΠΈΠ΄ΡΠΎΠΊΡΠΈΠ΄Ρ ΡΠ΅Π΄ΠΊΠΎΠ·Π΅ΠΌΠ΅Π»ΡΠ½ΡΡ
ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² ΡΠ²Π»ΡΡΡΡΡ ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΡΠΌΠΈ ΠΏΡΠ΅ΠΊΡΡΡΠΎΡΠ°ΠΌΠΈ Π΄Π»Ρ ΡΠΎΠ·Π΄Π°Π½ΠΈΡ ΠΌΠ½ΠΎΠ³ΠΎΡΡΠ½ΠΊΡΠΈΠΎΠ½Π°Π»ΡΠ½ΡΡ
ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ². Π‘ΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΠ΅ ΠΊΠ°ΡΠ±ΠΎΠ½Π°Ρ-ΠΈΠΎΠ½ΠΎΠ² Π² ΡΡΠΈΡ
ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΡΡ
Π½Π΅Π³Π°ΡΠΈΠ²Π½ΠΎ ΡΠΊΠ°Π·ΡΠ²Π°Π΅ΡΡΡ Π½Π° ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ²ΠΎΠΉΡΡΠ²Π° ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΈΠ· Π½ΠΈΡ
ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ². Π Π°Π·ΡΠ°Π±ΠΎΡΠ°Π½Π½Π°Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡ ΠΊΠ°ΡΠ±ΠΎΠ½Π°Ρ-ΠΈΠΎΠ½Ρ Π² ΡΠ»ΠΎΠΈΡΡΡΡ
Π³ΠΈΠ΄ΡΠΎΠΊΡΠΈΠ΄Π°Ρ
ΠΈΡΡΡΠΈΡ-Π΅Π²ΡΠΎΠΏΠΈΡ Π² Π΄ΠΈΠ°ΠΏΠ°Π·ΠΎΠ½Π΅ ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΡ ΡΠ³Π»Π΅ΡΠΎΠ΄Π° ΠΎΡ 0,05 Π΄ΠΎ 2,00 ΠΌΠ°Ρ. %. ΠΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΠΈ ΡΠΎΡΠ½ΠΎΡΡΠΈ Π΄Π»Ρ ΡΡΠΎΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠΈ Π΄ΠΎΡΡΠ°ΡΠΎΡΠ½ΠΎ Π½ΠΈΠ·ΠΊΠΈΠ΅ Π΄Π»Ρ ΡΠ°ΠΊΠΈΡ
Π½ΠΈΠ·ΠΊΠΈΡ
ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΉ.Layered rare earth hydroxides are promising precursors for creating multifunctional materials. The content of carbonate ions in these compounds negatively affects the optical properties of the materials synthesized from them. The developed technique makes it possible to determine carbonate ions in layered yttrium-europium hydroxides in the range of carbon content from 0.05 to 2.00 wt. %. The accuracy rates for this technique are quite low for such low concentrations
Highly Conductive Fe-Doped (La,Sr)(Ga,Mg)O3βΞ΄ Solid-State Membranes for Electrochemical Application
Membranes based on complex solid oxides with oxygen-ionic conductivity are widely used in high-temperature electrochemical devices such as fuel cells, electrolyzers, sensors, gas purifiers, etc. The performance of these devices depends on the oxygen-ionic conductivity value of the membrane. Highly conductive complex oxides with the overall composition of (La,Sr)(Ga,Mg)O3 have regained the attention of researchers in recent years due to the progress in the development of electrochemical devices with symmetrical electrodes. In this research, we studied how the introduction of iron cations into the gallium sublattice in (La,Sr)(Ga,Mg)O3 affects the fundamental properties of the oxides and the electrochemical performance of cells based on (La,Sr)(Ga,Fe,Mg)O3. It was found that the introduction of iron leads to an increase in the electrical conductivity and thermal expansion in an oxidizing atmosphere, while no such behavior was observed in a wet hydrogen atmosphere. The introduction of iron into a (La,Sr)(Ga,Mg)O3 electrolyte leads to an increase in the electrochemical activity of Sr2Fe1.5Mo0.5O6βΞ΄ electrodes in contact with the electrolyte. Fuel cell studies have shown that, in the case of a 550 Β΅m-thick Fe-doped (La,Sr)(Ga,Mg)O3 supporting electrolyte (Fe content 10 mol.%) and symmetrical Sr2Fe1.5Mo0.5O6βΞ΄ electrodes, the cell exhibits a power density of more than 600 mW/cm2 at 800 Β°C. Β© 2023 by the authors
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