Accreting neutron stars: composition of the upper layers of the inner crust

We model the nuclear evolution of an accreted matter as it sinks toward the stellar center, in order to find its composition and equation of state. To this aim, we developed a simplified reaction network that allows for redistribution of free neutrons in the inner crust to satisfy the recently suggested neutron hydrostatic and diffusion equilibrium condition. We analyse the main reaction pathways for the three representative thermonuclear ash compositions: Superburst, Kepler, and Extreme rp. In contrast to the previous results, which neglect redistribution of free (unbound) neutrons in the inner crust, the most significant reactions in our calculations are neutron captures and electron emissions. The pycnonuclear fusion plays some role only for Kepler ashes. For the direct application of our results in astrophysical codes we present profiles of the average charge, $\langle Z\rangle$, impurity parameter, $Q_\mathrm{imp}$ and equation of state for a set of models, parametrized by the pressure at the outer-inner crust interface. Typically, for Superburst ashes $Q_\mathrm{imp}\approx 1-4$, while for Kepler ashes $Q_\mathrm{imp}$ decreases from $\approx23$ at the outer-inner crust interface to $\approx5$ at the end of our simulation (the corresponding density equals $\rho_\mathrm{dc}\approx2\times 10^{12}$ g cm$^{-3}$). At the same time, for Extreme rp ashes $Q_\mathrm{imp}$ remains large $\approx 30-35$ in the considered inner crust region. Our results are important for modeling the thermal relaxation of transiently accreting neutron stars after the end of the outburst.Comment: 11 pages, 4 figures. Submitted to MNRA

Aseguramiento de protección contra el fuego en complejos industriales de agrupaciones animales

This study deals with ensuring fire safety in buildings of a cluster animal industrial complex by optimizing legislative measures and analyzing factors that affect the quality and reliability of the results of calculating fire risk. The research involved the following methods: expert assessment; calculating individual fire risk; modeling evacuation of people in the form of an individual flow model of human traffic. The conceptual features of the complex's buildings required developing the design and technical solutions that would reduce inefficient costs on the one hand, and, on the other, would ensure meeting fire safety requirements. The individual fire risk for employees of the asset to be protected is 2.91 ×10-7 per year-1 (0.291 ×10-6 per year). That is, it does not exceed the characteristic value established by Federal law No. 123-FZ dated 22.07.2008 'Technical regulations on fire safety'. After the introduction of the fire risk assessment system at the legislative level, the owners of objects have received the opportunity to optimize the cost of fire safety and the required level of human safety.Aquí se presenta el estudio del aseguramiento de la protección contra el fuego en edificios agrupados de un conjunto de ganadería por medio de optimizar las medidas legislativas respectivas y analizar las influencias en la calidad y fiabilidad de los resultados de evaluar riesgos de incendio. Se llevaron a cabo los estudios a través de hacer valoración profesional, calcular riesgos de incendio individuales y simular la evacuación de la gente en el modelo de flujos humanos individual y en cadena. Los aspectos funcionales conceptuales de los edificios del conjunto resultaron en la necesidad de desarrollar soluciones técnicas y estructurales que podrían ayudar a reducir gastos ineficientes y armonizarían los edificios con las exigencias de la protección contra el fuego. El riesgo de incendios indivudual para los trabajadores del objeto de protección considerado es 2.91x10-7 por año-1 (0.291x10-6 por año), es decir, no sobrepasa el nivel normal establecido por la ley Federal 123-FZ del 22 de Julio de 2008 «Regulaciones Técnicas de las Exigencias a la Protección contra el Fuego». La adopción en el nivel legislativo del sistema de valorar riesgos de incendio creó para los dueños de objetos la oportunidad de optimizar los gastos para asegurar la protección contra el fuego, incluyendo el aseguramiento del nivel exigido de seguridad humana

Aseguramiento de protección contra el fuego en complejos industriales de agrupaciones animales

Aquí se presenta el estudio del aseguramiento de la protección contra el fuego en edificios agrupados de un conjunto de ganadería por medio de optimizar las medidas legislativas respectivas y analizar las influencias en la calidad y fiabilidad de los resultados de evaluar riesgos de incendio. Se llevaron a cabo los estudios a través de hacer valoración profesional, calcular riesgos de incendio individuales y simular la evacuación de la gente en el modelo de flujos humanos individual y en cadena. Los aspectos funcionales conceptuales de los edificios del conjunto resultaron en la necesidad de desarrollar soluciones técnicas y estructurales que podrían ayudar a reducir gastos ineficientes y armonizarían los edificios con las exigencias de la protección contra el fuego. El riesgo de incendios individual para los trabajadores del objeto de protección considerado es 2.91x10-7 por año-1 (0.291x10-6 por año), es decir, no sobrepasa el nivel normal establecido por la ley Federal 123-FZ del 22 de Julio de 2008 «Regulaciones Técnicas de las Exigencias a la Protección contra el Fuego". La adopción en el nivel legislativo del sistema de valorar riesgos de incendio creó para los dueños de objetos la oportunidad de optimizar los gastos para asegurar la protección contra el fuego, incluyendo el aseguramiento del nivel exigido de seguridad human

Abstract OR-3: Integrative Structural Study of the Complex of Snake Toxin WTX with α7-type Nicotinic Acetylcholine Receptor

Background: Nicotinic acetylcholine receptors are ligand-gated ion channels present in the nervous system, epithelium, and the immune system. The α7-type nicotinic receptor (α7-nAChR) is a homopentameric membrane protein containing five ligand binding sites located at the interface between subunits in the extracellular domain of the receptor. α7-nAChR is considered a promising target for the treatment of cancer and cognitive dysfunction in Alzheimer's disease, schizophrenia, and depression. WTX is a non-conventional three-finger neurotoxin from the Naja kaouthia venom inhibiting α7-nAChR. WTX structure consists of three loops protruding from the “head” (core) stabilized by a system of disulfide bonds. Methods: The complex of the α7-nAChR extracellular domain with a recombinant analogue of WTX was studied by cryo-electron microscopy. The structure of the complex of full-length α7-nAChR with the toxin in the membrane environment was reconstructed by in silico molecular modeling. Interaction of WTX with the lipid membrane was confirmed by NMR-spectroscopy. Results: Analysis of electronic images confirmed the homopentameric organization of the extracellular domain with a diameter of ~ 9 nm and a height of ~ 7 nm. On the electron density map, additional regions corresponding to five WTX molecules located at the intersubunit interfaces of the domain were observed. Fitting the known spatial structures of the extracellular domain and the WTX toxin into the obtained electron density made it possible to reconstruct the structure of the complex (although with a low resolution of ~ 8 Ǻ due to the predominant orientation of particles in the ice) and to determine the topology of the toxin-receptor interaction. It was revealed that WTX interacts with the extracellular domain of α7-nAChR by the loop II, while the loop I and the toxin’s head seem to interact with the surface of the lipid membrane surrounding the receptor. Model of the complex of the full-length α7-nAChR receptor with WTX in the membrane environment corresponding to the neuronal membrane was constructed using computer simulation methods. Molecular dynamics for >1500 ns confirmed the stability of the complex. The predicted membrane-active site of the WTX molecule includes residues Lys13 and Arg18. The study of WTX and its mutants Lys13Ala and Arg18Ala by NMR-spectroscopy confirmed the importance of these residues for interaction with lipid membrane. Conclusion: Interaction mode of non-conventional neurotoxins with nAChR has been determined for the first time

The origins and spread of domestic horses from the Western Eurasian steppes

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: All collapsed and paired-end sequence data for samples sequenced in this study are available in compressed fastq format through the European Nucleotide Archive under accession number PRJEB44430, together with rescaled and trimmed bam sequence alignments against both the nuclear and mitochondrial horse reference genomes. Previously published ancient data used in this study are available under accession numbers PRJEB7537, PRJEB10098, PRJEB10854, PRJEB22390 and PRJEB31613, and detailed in Supplementary Table 1. The genomes of ten modern horses, publicly available, were also accessed as indicated in their corresponding original publications57,61,85-87.NOTE: see the published version available via the DOI in this record for the full list of authorsDomestication of horses fundamentally transformed long-range mobility and warfare. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling at Botai, Central Asia around 3500 BC. Other longstanding candidate regions for horse domestication, such as Iberia and Anatolia, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes, especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 BC, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMC and ZFPM1 genes. Our results reject the commonly held association between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe around 3000 BC driving the spread of Indo-European languages. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium BC Sintashta culture

Accreting neutron stars: heating of the upper layers of the inner crust

Neutron stars in low-mass X-ray binaries are thought to be heated up by accretion-induced exothermic nuclear reactions in the crust. The energy release and the location of the heating sources are important ingredients of the thermal evolution models. Here we present thermodynamically consistent calculations of the energy release in three zones of the stellar crust: at the outer-inner crust interface, in the upper layers of the inner crust (up to the density $\rho \leq 2\times 10^{12}$ g cm$^{-3}$), and in the underlying crustal layers. We consider three representative models of thermonuclear ashes (Superburst, Extreme rp, and Kepler ashes). The energy release in each zone is parametrized by the pressure at the outer-inner crust interface, which encodes all uncertainties related to the physics of the deepest inner-crust layers. Our calculations allow us, in particular, to set new lower limits on the net energy release (per accreted baryon): $Q\gtrsim0.28$ MeV for Extreme rp ashes and Q~0.43-0.51 MeV for Superburst and Kepler ashes.Comment: 5 pages, 1 figure; submitted to MNRAS:Letter

Pasta Phases in Neutron Star Mantle: Extended Thomas–Fermi vs. Compressible Liquid Drop Approaches

Nuclear pasta phases in the neutron stars mantle can affect the mechanical and transport properties of superdense matter, thus playing an important role in the dynamics and evolution of neutron stars. In this paper, we compare results obtained by the Extended Thomas–Fermi (ETF) method with the compressible liquid drop model (CLDM), based on the thermodynamically consistent description of the surface properties calculated for the two-phase plane interface and the same energy-density functional (for numerical illustration, we applied the Skyrme-type functional SLy4). Our ETF calculations found that pasta phases in cylindrical form cover a significant crustal region (both normal and inverse phases, aka spaghetti and bucatini are presented). Meanwhile, within the applied CLDM framework, which includes the thermodynamically required effect of neutron adsorption on the cluster’s surface but neglects curvature corrections, only the spaghetti phase was found to be energetically favorable in the small density range prior to crust–core transition. On the other hand, the recent CLDM of Dinh Thi et al., 2021, which, on the contrary, accounts for curvature term but neglects neutron adsorption, predicts pasta phase onset in better agreement with the ETF. This fact highlights the importance of the curvature effects and allows counting on the potential validity of the CLDMs as a convenient, transparent and accurate tool for investigation of the pasta-phase properties