Microwave paleointensities indicate a low paleomagnetic dipole moment at the Permo-Triassic boundary

AbstractThe quantity of igneous material comprising the Siberian Traps provides a uniquely excellent opportunity to constrain Earth’s paleomagnetic field intensity at the Permo-Triassic boundary. There remains however, a contradiction about the strength of the magnetic field that is exacerbated by the limited number of measurement data. To clarify the geomagnetic field behavior during this time period, for the first time, a microwave paleointensity study has been carried out on the Permo-Triassic flood basalts in order to complement existing datasets obtained using conventional thermal techniques. Samples, which have been dated at ∼250Ma, of the Permo-Triassic trap basalts from the northern extrusive (Maymecha-Kotuy region) and the southeastern intrusive (areas of the Sytikanskaya and Yubileinaya kimberlite pipes) localities on the Siberian platform are investigated. These units have already demonstrated reliable paleomagnetic directions consistent with the retention of a primary remanence. Furthermore, Scanning Electron Microscope analysis confirms the presence of iron oxides likely of primary origin. Microwave Thellier-type paleointensity experiments (IZZI protocol with partial thermoremanent magnetization checks) are performed on 50 samples from 11 sites, of which, 28 samples from 7 sites provide satisfactory paleointensity data. The samples display corresponding distinct directional components, positive pTRM checks and little or no zig-zagging of the Arai or Zijderveld plot, providing evidence to support that the samples are not influenced by lab-induced alteration or multi-domain behavior. The accepted microwave paleointensity results from this study are combined with thermal Thellier-type results from previously published studies to obtain overall estimates for different regions of the Siberian Traps. The mean geomagnetic field intensity obtained from the samples of the northern part is 13.4±12.7μT (Maymecha-Kotuy region), whereas from the southeastern part is 17.3±16.5μT (Sytikanskaya kimberlite pipe) and 48.5±7.3μT (Yubileinaya kimberlite pipe), suggesting that the regional discrepancy is probably due to the insufficient sampling of geomagnetic secular variation, and thus, multiple localities need to be considered to obtain an accurate paleomagnetic dipole moment for this time period. It demonstrates that the overall mean paleointensity of the Siberian Traps is 19.5±13.0μT which corresponds to a mean virtual dipole moment of 3.2±1.8×1022Am2. Results indicate that the average magnetic field intensity during Permo-Triassic boundary is significantly lower (by approximately 50%) than the present geomagnetic field intensity, and thus, it implies that the Mesozoic dipole low might extend 50Myr further back in time than previously recognized

Statistical Properties and Predictability of Extreme Epileptic Events

The use of extreme events theory for the analysis of spontaneous epileptic brain activity is a relevant multidisciplinary problem. It allows deeper understanding of pathological brain functioning and unraveling mechanisms underlying the epileptic seizure emergence along with its predictability. The latter is a desired goal in epileptology which might open the way for new therapies to control and prevent epileptic attacks. With this goal in mind, we applied the extreme event theory for studying statistical properties of electroencephalographic (EEG) recordings of WAG/Rij rats with genetic predisposition to absence epilepsy. Our approach allowed us to reveal extreme events inherent in this pathological spiking activity, highly pronounced in a particular frequency range. The return interval analysis showed that the epileptic seizures exhibit a highly-structural behavior during the active phase of the spiking activity. Obtained results evidenced a possibility for early (up to 7 s) prediction of epileptic seizures based on consideration of EEG statistical properties

КЛИНИЧЕСКИЙ СЛУЧАЙ ЭНДОВАСКУЛЯРНОГО ЛЕЧЕНИЯ ПОСТТРАВМАТИЧЕСКОЙ АНЕВРИЗМЫ ПОЧЕЧНОЙ АРТЕРИИ

Introduction. Aneurysm of renal artery is a rare and complex pathology of renal bloodstream. Large percentage of observations show that renal artery aneurysms are iatrogenic and happen due to urological interventions. Traumatic aneurysms are much less frequent. By the nature of the blood supply arterial aneurysms are subdiveded into those, which occur when the injured organ is only artery and arteriovenous aneurysms that occur while an artery is damaged along with the accompanying veins. Aneurysms may be treated only surgically, and the only exception is pregnancy. It is possible to use the open treatment option such as aneurysm resection with prosthetics, reanastomosing or its collateral plastics of the renal artery; exclusion of aneurysm with shunting of renal artery or its branches; resection of aneurysm with anastomosing of artery with azygos splanchnic arteries; complex reconstruction using autovein or internal iliac artery segment; including kidney resection at local infarction or nephrectomy in the case of evident nephrosclerosis.Materials and methods. This paper presents a clinical case of successful minimally invasive surgical treatment of traumatic aneurysm of renal artery. It was carried out through stenting of the right lowpolar renal artery: a coronary sheath was used to transfuse and implant the Explorer-Itgimedical Aneugraft 3.0 * 18.0 mm graft-system; the stent-graft was implanted into the right lowpolar renal artery so that it covers the aneurysm ostium. Results. The above case shows the possibility to successfully apply the endovascular method to treat posttraumatic aneurysms of renal arteries with derivative circulation.Conclusion. This technique can be safely and successfully used as an alternative to the traditional «open» surgery, as it is minimally invasive, and allows performing a complete blockade of the pathological blood flow and to avoid an additional operating trauma and compromenation of distal branches. Введение. Аневризма почечных артерий – редкая и сложная патология сосудистого русла почки. В большом проценте наблюдений аневризмы почечных артерий являются ятрогенными, возникающими в результате интервенционных урологических вмешательств. Травматические аневризмы встречаются значительно реже. По характеру кровоснабжения различают артериальные аневризмы, возникающие при ранении только артерии, и артериовенозные аневризмы, возникающие при одновременном повреждении артерии и сопутствующей вены. Лечение аневризм возможно только хирургическим способом, исключением является только беременность. Возможно применение открытых методов лечения, таких как резекция аневризмы с протезированием, реанастомозированием или ее боковой пластикой почечной артерии; выключение аневризмы с шунтированием почечной артерии или ее ветвей; резекция аневризмы с анастомозированием артерии с непарными висцеральными артериями; сложные реконструкции с использованием аутовены или сегмента внутренней подвздошной артерии; в том числе применение резекции почки при локальном инфаркте или нефрэктомии в случае выраженного нефросклероза. Материалы и методы. В данной работе представлен клинический случай успешного малоинвазивного хирургического лечения травматической аневризмы почечной артерии. Для этого выполнено стентирование правой нижнеполюсной почечной артерии: по коронарному проводнику проведена и имплантирована графт-система Itgimedical Aneugraft 3,0*18,0 мм – стент-графт имплантирован в нижнеполюсную правую почечную артерию с перекрытием шейки аневризмы.Результаты. Приведенный случай показывает возможность успешного применения эндоваскулярного метода для лечения посттравматических аневризм почечных артерий с артериовенозным сбросом.Заключение. Данная методика может безопасно и с успехом применяться в качестве альтернативы традиционного «открытого» хирургического вмешательства, поскольку она малоинвазивна, позволяет выполнять полную блокаду патологического кровотока, избегать дополнительной операционной травмы и компрометации дистальных ветвей.

The c4h, tat, hppr and hppd Genes Prompted Engineering of Rosmarinic Acid Biosynthetic Pathway in Salvia miltiorrhiza Hairy Root Cultures

Rational engineering to produce biologically active plant compounds has been greatly impeded by our poor understanding of the regulatory and metabolic pathways underlying the biosynthesis of these compounds. Here we capitalized on our previously described gene-to-metabolite network in order to engineer rosmarinic acid (RA) biosynthesis pathway for the production of beneficial RA and lithospermic acid B (LAB) in Salvia miltiorrhiza hairy root cultures. Results showed their production was greatly elevated by (1) overexpression of single gene, including cinnamic acid 4-hydroxylase (c4h), tyrosine aminotransferase (tat), and 4-hydroxyphenylpyruvate reductase (hppr), (2) overexpression of both tat and hppr, and (3) suppression of 4-hydroxyphenylpyruvate dioxygenase (hppd). Co-expression of tat/hppr produced the most abundant RA (906 mg/liter) and LAB (992 mg/liter), which were 4.3 and 3.2-fold more than in their wild-type (wt) counterparts respectively. And the value of RA concentration was also higher than that reported before, that produced by means of nutrient medium optimization or elicitor treatment. It is the first report of boosting RA and LAB biosynthesis through genetic manipulation, providing an effective approach for their large-scale commercial production by using hairy root culture systems as bioreactors

X-ray polarimetry reveals the magnetic field topology on sub-parsec scales in Tycho's supernova remnant

Supernova remnants are commonly considered to produce most of the Galactic cosmic rays via diffusive shock acceleration. However, many questions about the physical conditions at shock fronts, such as the magnetic-field morphology close to the particle acceleration sites, remain open. Here we report the detection of a localized polarization signal from some synchrotron X-ray emitting regions of Tycho's supernova remnant made by the Imaging X-ray Polarimetry Explorer. The derived polarization degree of the X-ray synchrotron emission is 9+/-2% averaged over the whole remnant, and 12+/-2% at the rim, higher than the 7-8% polarization value observed in the radio band. In the west region the polarization degree is 23+/-4%. The X-ray polarization degree in Tycho is higher than for Cassiopeia A, suggesting a more ordered magnetic-field or a larger maximum turbulence scale. The measured tangential polarization direction corresponds to a radial magnetic field, and is consistent with that observed in the radio band. These results are compatible with the expectation of turbulence produced by an anisotropic cascade of a radial magnetic-field near the shock, where we derive a magnetic-field amplification factor of 3.4+/-0.3. The fact that this value is significantly smaller than those expected from acceleration models is indicative of highly anisotropic magnetic-field turbulence, or that the emitting electrons either favor regions of lower turbulence, or accumulate close to where the magnetic-field orientation is preferentially radially oriented due to hydrodynamical instabilities.Comment: 31 pages, 7 figures, 3 tables. Accepted for publication in ApJ. Revised versio

Magnetic structures and turbulence in SN 1006 revealed with imaging X-ray polarimetry

Young supernova remnants (SNRs) strongly modify surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). X-ray polarization measurements probe magnetic field morphology and turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell of SN1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer (IXPE). We found an average polarization degree of $22.4\pm 3.5\%$ and an average polarization angle of $-45.4\pm 4.5^\circ$ (measured on the plane of the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed, similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the remnant, favoring that CR-induced instabilities set the turbulence in SN 1006 and CR acceleration is environment-dependent.Comment: 15 pages, 4 Figures, 2 Tables; accepted for publication in The Astrophysical Journa

X-ray polarimetry of the accreting pulsar GX 301-2

The phase- and energy-resolved polarization measurements of accreting X-ray pulsars (XRPs) allow us to test different theoretical models of their emission, as well as to provide an avenue to determine the emission region geometry. We present the results of the observations of the XRP GX 301-2 performed with the Imaging X-ray Polarimetry Explorer (IXPE). GX 301-2 is a persistent XRP with one of the longest known spin periods of ~680 s. A massive hyper-giant companion star Wray 977 supplies mass to the neutron star via powerful stellar winds. We do not detect significant polarization in the phase-averaged data using spectro-polarimetric analysis, with the upper limit on the polarization degree (PD) of 2.3% (99% confidence level). Using the phase-resolved spectro-polarimetric analysis we get a significant detection of polarization (above 99% c.l.) in two out of nine phase bins and marginal detection in three bins, with a PD ranging between ~3% and ~10%, and a polarization angle varying in a very wide range from ~0 deg to ~160 deg. Using the rotating vector model we obtain constraints on the pulsar geometry using both phase-binned and unbinned analysis getting excellent agreement. Finally, we discuss possible reasons for a low observed polarization in GX 301-2.Comment: 10 pages, 10 figures, submitted to A&

A polarimetrically oriented X-ray stare at the accreting pulsar EXO 2030+375

Accreting X-ray pulsars (XRPs) are presumably ideal targets for polarization measurements, as their high magnetic field strength is expected to polarize the emission up to a polarization degree of ~80%. However, such expectations are being challenged by recent observations of XRPs with the Imaging X-ray Polarimeter Explorer (IXPE). Here we report on the results of yet another XRP, EXO 2030+375, observed with IXPE and contemporarily monitored with Insight-HXMT and SRG/ART-XC. In line with recent results obtained with IXPE for similar sources, analysis of the EXO 2030+375 data returns a low polarization degree of 0%-3% in the phase-averaged study and variation in the range 2%-7% in the phase-resolved study. Using the rotating vector model we constrain the geometry of the system and obtain a value for the magnetic obliquity of ~$60^{\circ}$. Considering also the estimated pulsar inclination of ~$130^{\circ}$, this indicates that the magnetic axis swings close to the observer line of sight. Our joint polarimetric, spectral and timing analysis hint to a complex accreting geometry where magnetic multipoles with asymmetric topology and gravitational light bending significantly affect the observed source behavior.Comment: A&A accepted. Proofs versio