The nature of the high Galactic latitude O-star HD93521: new results from X-ray and optical spectroscopy

Owing to its unusual location and its isolation, the nature of the high Galactic latitude O9.5Vp object HD93521 is still uncertain. We have collected X-ray and optical observations to characterize the star and its surroundings. X-ray images and spectra are analyzed to search for traces of a recent star formation event around HD93521 and to search for the signature of a possible compact companion. Optical echelle spectra are analysed with plane-parallel model atmosphere codes, assuming either a spherical star or a gravity darkened rotationally flattened star, to infer the effective temperature and surface gravity, and to derive the He, C, N and O abundances of HD93521. The X-ray images reveal no traces of a population of young low-mass stars coeval with HD93521. The X-ray spectrum of HD93521 is consistent with a normal late O-type star although with subsolar metallicity. No trace of a compact companion is found in the X-ray data. In the optical spectrum, He and N are found to be overabundant, in line with the effect of rotational mixing in this very fast rotator, whilst C and O are subsolar. A critical comparison with the properties of subdwarf OB stars, indicates that, despite some apparent similarities, HD93521 does not belong to this category. Despite some ambiguities on the runaway status of the star, the most likely explanation is that HD93521 is a Population I massive O-type star that was ejected from the Galactic plane either through dynamical interactions or a result of a supernova event in a binary system.Comment: Accepted for publication in Astronomy & Astrophysic

Arginine–glycine–aspartic acid functional branched semi-interpenetrating hydrogels

For the first time a series of functional hydrogels based on semi-interpenetrating networks with both branched and crosslinked polymer components have been prepared and we show the successful use of these materials as substrates for cell culture. The materials consist of highly branched poly(N-isopropyl acrylamide)s with peptide functionalised end groups in a continuous phase of crosslinked poly(vinyl pyrrolidone). Functionalisation of the end groups of the branched polymer component with the GRGDS peptide produces a hydrogel that supports cell adhesion and proliferation. The materials provide a new synthetic functional biomaterial that has many of the features of extracellular matrix, and as such can be used to support tissue regeneration and cell culture. This class of high water content hydrogel material has important advantages over other functional hydrogels in its synthesis and does not require postprocessing modifications nor are functional-monomers, which change the polymerisation process, required. Thus, the systems are amenable to large scale and bespoke manufacturing using conventional moulding or additive manufacturing techniques. Processing using additive manufacturing is exemplified by producing tubes using microstereolithography

How to scrutinise a Production Sharing Agreement: A guide for the oil and gas sector based on experience from the Caspian region

This guide discusses the provisions of a particular type of oil and gas contract, the Production Sharing Agreement (PSA). While the guide is aimed at a general civil society readership, it draws particularly on experience from Kazakhstan. The purpose of this guide is to give an accessible account of some key characteristics of PSAs, with a focus on revenue issues, and to suggest action points for civil society organisations involved with monitoring extractive industries. Indeed, in recent years the public in resource-rich states has become increasingly concerned about the management of extractive industry revenues

The Significance of Marxist Methodology in Modern Historical Science

The role and significance of Marxist methodology in historical research is considered. The conclusion is made about the prospects of the methodological apparatus of Marxism in the era of establishing methodo­logical pluralism in humanitarian science.Рассматривается роль и значение марксистской методологии в исторических исследованиях. Делается вывод о перспективах методологического аппарата марксизма в эпоху установления в гуманитарной науке методологического плюрализма

Algorithm for Endovascular Treatment of Patients With Spinal Arteriovenous Malformations

Objective: To compare the endovascular treatment results in patients with spinal arteriovenous malformations (AVM) based on the proposed algorithm.   Materials and methods: We retrospectively analyzed the endovascular treatment results in 72 patients with various types of spinal AVMs for 2014-2021. We formed 2 main groups of patients based on the developed indications for neurophysiological monitoring and provocative tests (NFM and PT): group 1 (n = 63) was treated according to the algorithm, and group 2 (n = 9) was treated before the algorithm was implemented. Group 1 was divided into subgroup 1.1 (n = 42) including patients with no indications for NFM and PT and subgroup 1.2 (n = 21) with patients indicated for NFM and PT. Subgroup 1.2 was further divided into subsubgroup 1.2A (n = 2) with patients indicated for NFM and PT yet to be informative due to severe neurological deficit and subsubgroup 1.2B (n = 19) with patients that had indications for and successfully underwent NFM and PT. We compared patients between groups 1 and 2, subsubgroup 1.2B and group 2 to evaluate the effectiveness of the algorithm (radical nature of the treatment, functional status assessment, complications).   Results: Radical nature of spinal AVM treatment in group 1 was 79 % compared with 44 % in group 2 (P = 0.043). There was a significant improvement in motor function in group 1 compared with group 2 in each follow-up period (Р ≤ 0.007). Comparison of subsubgroup 1.2B and group 2 showed no significant differences (P = .05). The treatment led to complications in 5 patients (7 % of the total number of patients with spinal AVMs): 4 patients in group 2 and 1 patient in subsubgroup 1.2B. The effectiveness of the developed criteria was indirectly confirmed by difference in complications number between subsubgroup 1.2B and group 2 (P = 0.001).   Conclusions: Group 1 showed better treatment results, significant clinical improvement, high radical nature of treatment, and a low percentage of complications compared with group 2. The proposed algorithm proved effective for main tasks of endovascular treatment of spinal AVMs

E-Government in Modern Russia: State and Prospects of Development

В данной статье представлено современное состояние электронного правительства в России, а именно изучена современная позиция Российской Федерации в глобальном рейтинге ООН развития электронного правительства. Автор в статье приводит преимущества использования электронного правительства, также определяет проблемы развития электронного правительства в России и направления его развития.This article presents the current state of e-government in Russia, namely, the current position of the Russian Federation in the UN global ranking of e-government development. The author in the article gives the advantages of using e-government, the author also identified the problems of e-government development in Russia and the directions of its development

Power characteristics of the metal compounds formation process during the friction stir welding

An influence of the power characteristics on the formation process of the uniform metals compound during the welding with friction stirringis being examined in this article.A dependency between the machine-tool engine power input and the instrument tilt during the FSW for the aluminum alloy AD31, copper alloy M1, titanium alloy OT4-1 and steel St-3 low-alloyed has been explored. A question of the stabilization of power consumption process while the establishment of superplastic condition of welded metal during the FSW has also been reviewed. A dependency revealed between the power characteristics, the geometry of the formation, the rotation speeds, the longitudinal displacement of the tool and its dimensions for fixed values of the parameters during the FSW

Development of invasive EEG in epilepsy surgery (review)

There are different diagnostic methods that used for localization of the seizure onset zone in focal refractory epilepsy cases. Invasive video-EEG recording is the «gold standard» in determining the epileptogenic zone among other diagnostic methods. Invasive EEG already has a long history of using. This article provides historical review and analysis of the techniques, their advantages and disadvantages, current issues

Reorganization of brain networks in olfactory groove meningioma patients: a pilot resting-state fMRI study

BackgroundOlfactory groove meningioma (OGM) is frequently associated with neuropsychological and behavioral impairments. However, there is currently a lack of evidence on the pathobiology of these functional alterations. In this study, our objective was to evaluate functional connectivity disturbances in patients with OGMs compared to healthy controls.MethodsNineteen patients with OGMs and twenty healthy controls were enrolled. The seed-based functional connectivity analysis used the main hubs of the default mode network (DMN), salience network (SN), and fronto-parietal network (FPN) as seeds. Region-of-interest (ROI)-to-voxel second-level analysis was conducted, revealing the most significant clusters of differences in brain functional connectivity between the groups.ResultsPatients with OGMs demonstrated significant alterations in resting-state functional connectivity within the DMN, SN, and FPN compared to controls. Specifically, within the DMN, we identified abnormal connectivity patterns involving the medial prefrontal cortex bilaterally, posterior cingulate cortex bilaterally, and right posterolateral cortex. In the SN, we observed enhanced functional connectivity between the anterior cingulate cortex bilaterally and left frontal, temporal, and insular regions. Additionally, the FPN exhibited disrupted connectivity of the right posterior parietal cortex with other brain areas. Notably, some connectivity changes were related to perilesional edema volume, visual acuity, and clinical metrics (KPS and MoCA scores).ConclusionWe revealed significant alterations in DMN, SN, and FPN function in patients with olfactory groove meningiomas compared with controls. These changes were associated with clinical variables and lesion characteristics. To our knowledge, this is the first report on rs-fMRI alterations in patients with olfactory groove meningiomas

Complex-Radical Copolymerization of Vinylcyclohexyl Ketones with Maleic Anhydride and N-p-tolylmaleimide

Some features of the formation and photochemical reactions of cyclohexylketone containing macromolecules including copolymers of vinylcyclohexyl ketone (VCHK) and its derivatives (V-a-Cl-CHK and V- d-C1-CHK) with maleic anhydride (MA) and N-p-tolylmaleimide (TMI) have been revealed. It has been established that keto-enol tautomerism is the only reaction realized in the vinylcyclohexylketone molecules having mobile hydrogen atom at a -position in the cyclohexane ring, enol form of which is formed by charge-transfer complexes with anhydride or imide of maleic acid as acceptor monomers. The kinetic parameters of these reactions, including complex-formation and copolymerization constants, as well as the ratios of chain growth rates for the participation of monomeric charge-transfer complexes and free monomers,В are all determined. It is shown that an alternative copolymerization is realized with the monomer systems containing VCHK and V- d -C1-CHK, which are carried out through a complex-mechanism due to the keto-enol tautomerism; while random copolymer enriched with vinyl ketone units is formed with the system containing oc-substituted VCHK. It is found that characteristics of photochemical reactions ofВ alternating copolymer synthesized depend on the type of substitutation in the vinyl ketone molecule; unlink VCHK-MA(TMI) and V-d-C1-CHK-MA(TMI) copolymers case which easily crosslink upon UVirradiation, and the N-substituted derivatives of these copolymers which decompose under similar condition