Loss of coherence in dynamical networks: spatial chaos and chimera states

We discuss the breakdown of spatial coherence in networks of coupled oscillators with nonlocal interaction. By systematically analyzing the dependence of the spatio-temporal dynamics on the range and strength of coupling, we uncover a dynamical bifurcation scenario for the coherence-incoherence transition which starts with the appearance of narrow layers of incoherence occupying eventually the whole space. Our findings for coupled chaotic and periodic maps as well as for time-continuous R\"ossler systems reveal that intermediate, partially coherent states represent characteristic spatio-temporal patterns at the transition from coherence to incoherence.Comment: 4 pages, 4 figure

Diagnosing numerical Cherenkov instabilities in relativistic plasma simulations based on general meshes

Numerical Cherenkov radiation (NCR) or instability is a detrimental effect frequently found in electromagnetic particle-in-cell (EM-PIC) simulations involving relativistic plasma beams. NCR is caused by spurious coupling between electromagnetic-field modes and multiple beam resonances. This coupling may result from the slow down of poorly-resolved waves due to numerical (grid) dispersion and from aliasing mechanisms. NCR has been studied in the past for finite-difference-based EM-PIC algorithms on regular (structured) meshes with rectangular elements. In this work, we extend the analysis of NCR to finite-element-based EM-PIC algorithms implemented on unstructured meshes. The influence of different mesh element shapes and mesh layouts on NCR is studied. Analytic predictions are compared against results from finite-element-based EM-PIC simulations of relativistic plasma beams on various mesh types.Comment: 31 pages, 20 figure

Hybrid simulations of the cusp and dayside magnetosheath dynamics under \ quasi-radial interplanetary magnetic fields

Under quasi-radial interplanetary magnetic fields (IMF), foreshock turbulence can have an impact on the magnetosheath and cusps depending on the location of the quasi-parallel shock. We perform three-dimensional simulations of Earth's dayside magnetosphere using the hybrid code HYPERS, and compare northward and southward quasi-radial IMF configurations. We study the magnetic field configuration, fluctuations in the magnetosheath and the plasma in the regions around the northern cusp. Under northward IMF with Earthward $B_x$, there is a time-varying plasma depletion layer immediately outside the northern cusp. In the southward IMF case, the impact of foreshock turbulence and high-speed jets, together with magnetopause reconnection, can lead to strong density enhancements in the cusp.Comment: Accepted by JGR: Space physic

Non-homologous isofunctional enzymes: A systematic analysis of alternative solutions in enzyme evolution

<p>Abstract</p> <p>Background</p> <p>Evolutionarily unrelated proteins that catalyze the same biochemical reactions are often referred to as analogous - as opposed to homologous - enzymes. The existence of numerous alternative, non-homologous enzyme isoforms presents an interesting evolutionary problem; it also complicates genome-based reconstruction of the metabolic pathways in a variety of organisms. In 1998, a systematic search for analogous enzymes resulted in the identification of 105 Enzyme Commission (EC) numbers that included two or more proteins without detectable sequence similarity to each other, including 34 EC nodes where proteins were known (or predicted) to have distinct structural folds, indicating independent evolutionary origins. In the past 12 years, many putative non-homologous isofunctional enzymes were identified in newly sequenced genomes. In addition, efforts in structural genomics resulted in a vastly improved structural coverage of proteomes, providing for definitive assessment of (non)homologous relationships between proteins.</p> <p>Results</p> <p>We report the results of a comprehensive search for non-homologous isofunctional enzymes (NISE) that yielded 185 EC nodes with two or more experimentally characterized - or predicted - structurally unrelated proteins. Of these NISE sets, only 74 were from the original 1998 list. Structural assignments of the NISE show over-representation of proteins with the TIM barrel fold and the nucleotide-binding Rossmann fold. From the functional perspective, the set of NISE is enriched in hydrolases, particularly carbohydrate hydrolases, and in enzymes involved in defense against oxidative stress.</p> <p>Conclusions</p> <p>These results indicate that at least some of the non-homologous isofunctional enzymes were recruited relatively recently from enzyme families that are active against related substrates and are sufficiently flexible to accommodate changes in substrate specificity.</p> <p>Reviewers</p> <p>This article was reviewed by Andrei Osterman, Keith F. Tipton (nominated by Martijn Huynen) and Igor B. Zhulin. For the full reviews, go to the Reviewers' comments section.</p

The Link Between Shocks, Turbulence and Magnetic Reconnection in Collisionless Plasmas

Global hybrid (electron fluid, kinetic ions) and fully kinetic simulations of the magnetosphere have been used to show surprising interconnection between shocks, turbulence and magnetic reconnection. In particular collisionless shocks with their reflected ions that can get upstream before retransmission can generate previously unforeseen phenomena in the post shocked flows: (i) formation of reconnecting current sheets and magnetic islands with sizes up to tens of ion inertial length. (ii) Generation of large scale low frequency electromagnetic waves that are compressed and amplified as they cross the shock. These \u27wavefronts\u27 maintain their integrity for tens of ion cyclotron times but eventually disrupt and dissipate their energy. (iii) Rippling of the shock front, which can in turn lead to formation of fast collimated jets extending to hundreds of ion inertial lengths downstream of the shock. The jets, which have high dynamical pressure, \u27stir\u27 the downstream region, creating large scale disturbances such as vortices, sunward flows, and can trigger flux ropes along the magnetopause. This phenomenology closes the loop between shocks, turbulence and magnetic reconnection in ways previously unrealized. These interconnections appear generic for the collisionless plasmas typical of space, and are expected even at planar shocks, although they will also occur at curved shocks as occur at planets or around ejecta

Statistical study of magnetosheath jet‐driven bow waves

When a magnetosheath jet (localized dynamic pressure enhancements) compresses ambient magnetosheath at a (relative) speed faster than the local magnetosonic speed, a bow wave or shock can form ahead of the jet. Such bow waves or shocks were recently observed to accelerate particles, thus contributing to magnetosheath heating and particle acceleration in the extended environment of Earth’s bow shock. To further understand the characteristics of jet‐driven bow waves, we perform a statistical study to examine which solar wind conditions favor their formation and whether it is common for them to accelerate particles. We identified 364 out of 2859 (~13%) magnetosheath jets to have a bow wave or shock ahead of them with Mach number typically larger than 1.1. We show that large solar wind plasma beta, weak interplanetary magnetic field (IMF) strength, large solar wind Alfvén Mach number, and strong solar wind dynamic pressure present favorable conditions for their formation. We also show that magnetosheath jets with bow waves or shocks are more frequently associated with higher maximum ion and electron energies than those without them, confirming that it is common for these structures to accelerate particles. In particular, magnetosheath jets with bow waves have electron energy flux enhanced on average by a factor of 2 compared to both those without bow waves and the ambient magnetosheath. Our study implies that magnetosheath jets can contribute to shock acceleration of particles especially for high Mach number shocks. Therefore, shock models should be generalized to include magnetosheath jets and concomitant particle acceleration

Non-Maxwellian Proton Velocity Distributions in Nonradiative Shocks

The Balmer line profiles of nonradiative supernova remnant shocks provide the means to measure the post-shock proton velocity distribution. While most analyses assume a Maxwellian velocity distribution, this is unlikely to be correct. In particular, neutral atoms that pass through the shock and become ionized downstream form a nonthermal distribution similar to that of pickup ions in the solar wind. We predict the H alpha line profiles from the combination of pickup protons and the ordinary shocked protons, and we consider the extent to which this distribution could affect the shock parameters derived from H alpha profiles. The Maxwellian assumption could lead to an underestimate of shock speed by up to about 15%. The isotropization of the pickup ion population generates wave energy, and we find that for the most favorable parameters this energy could significantly heat the thermal particles. Sufficiently accurate profiles could constrain the strength and direction of the magnetic field in the shocked plasma, and we discuss the distortions from a Gaussian profile to be expected in Tycho's supernova remnant.Comment: 13 pages, 6 figure

Antiresorptive activity of denosumab in the treatment of osteoporosis in patients with rheumatoid arthritis

Background: fracture risks assessment and determination of bone mineral density are modern methods, generally accepted and widely used. However, they have limitations and disadvantages for the dynamic evaluation of bone remodeling processes in RA-patients with low BMD. The investigation of bone resorption markers is an important issue. Aims: to compare the antiresorptive activity of denosumab and alendronic acid in patients with rheumatoid arthritis and osteoporosis using -CTX and osteocalcin (OC). Materials and methods: forty-two patients were included in the study (16 patients were treated with denosumab, 13 patients with alendronic acid, 13 patients - control group without any osteoporosis treatment). The quantitative determination of -CTX and OC as well as dual-energy X-ray absorptionometry (DXA) were carried out for all patients at the first visit with consecutive investigation of bone resorption markers 3 months after. The predictive capacity was determined using the ratio of observed fractures/expected fractures by FRAX. Results: The level of -CTX 16% (median 861.6 pg/ml vs. 724.6 pg/ml, p = 0.049) and OC 39% (median 13.9 ng/ml vs 8.5 ng/ml, p = 0.047) decreased significantly in 3 month in RA patients treated with denosumab. The decrease of -CTX (median 858.9 pg/ml vs. 821.8 pg/ml) and OC (median 14.8 ng/ml vs. 13.9 ng/ml) was observed in the group of patients treated with alendronic acid, but not reached statistical significance. Conclusions: denosumab had showed better antiresorptive activity compared with bisphosphonates, which was registered 3 month after the start of the treatment

Особливості хірургічного лікування спортивної грижі у футболістів

The aim of the work: to determine the optimal way to choose the method of surgical treatment for sports hernia in football players. Materials and Methods. An analysis of the results of surgical treatment of 36 football players of professional and amateur clubs aged 18 to 34 years with a diagnosis of sports hernia, who were in the Surgical Department of Kyiv City Clinical Hospital No. 3 in 2014–2019. Patients were divided into two groups of studies depending on the method of surgery. In group 1 there were two subgroups, subgroup 1 of patients included 10 football players, who underwent laparoscopic intraperitoneal hernia alloplasty according to the IPOM method. Subgroup 2 included 8 football players, who underwent laparoscopic intraperitoneal hernia alloplasty according to the IPOM method with subdermal suturing of the internal inguinal rings. Group 2 included 18 football players, who underwent laparoscopic transabdominal preperitoneal hernia alloplasty (ТАРР). The Copenhagen Hip and Groin Outcome Score (HAGOS) and the Eura HS Quality of Life score (Eura HS-QoL in modification) were used to assess the quality of life indicators. Results and Discussion. In the analysis of indicators according to the HAGOS scale, the quality of life before surgery did not differ in both groups of the study, while after surgery significantly increased in group 2 from 47 to 96 points and group 1 – from 45 to 80 points (p &lt;0.05). Also group 2 there was a significant reduction in groin pain after laparoscopic hernioaloplasty (ТАРР) from 8 points to 2 points on the VAS in scale and after the application of IPOM in group 1 – from 7.5 to 3 points (p&lt;0.05). The shortest period for return of the athlete to play is 3 weeks after surgical treatment of sports hernia by ТАРР laparoscopic repair of the posterior wall of the inguinal canal with a self-fixing mesh. The study conducted a comparative analysis of the results of laparoscopic surgical methods and determined the optimal way to choose&nbsp;the method of surgical treatment for sports hernia in football players.Цель работы: определить оптимальную тактику выбора хирургического лечения спортивной грыжи у футболистов. Материалы и методы. &nbsp;Проведен анализ результатов хирургического лечения 36 футболистов профессиональных и аматорских клубов в возрасте от 18 до 34 лет с диагнозом спортивная грыжа, которые находились в хирургическом отделении КГКБ № 3 в 2014–2019 гг. Больные разделены на две группы исследования в зависимости от методики хирургического вмешательства. В первой группе выделены две подгруппы, в первую подгруппу больных вошли 10 футболистов, которым выполнялась лапароскопическая интраперитонеальная герниоаллопластика по методике IPOM. Во вторую подгруппу вошли 8 футболистов, которым выполнялась лапароскопическая интраперитонеальная герниоаллопластика по методике IPOM с субдермальным ушиванием внутренних паховых колец. Во вторую группу вошли 18 футболистов, которым выполнялась лапароскопическая трансабдоминальная преперитонеальна герниоаллопластика по методике TAPP. Для оценки показателей качества жизни применяли опросник The Copenhagen Hip and Groin Outcome Score (HAGOS) и Eura HS Quality of Life score (Eura HS-QoL в модификации). Результаты исследований и их обсуждение. При анализе показателей по шкале HAGOS качество жизни до операции не отличалось в обеих группах исследования, тогда как после проведения хирургического лечения качество жизни значительно повысилось во второй группе с 47 до 96 баллов и в первой группе с 45 до 80 баллов (р&lt;0,05). Также во второй группе отмечалось достоверное уменьшение болевого синдрома в паховой области после лапароскопической герниоаллопластики по методике ТАРР с 8 баллов до 2 баллов по шкале ВАШ и после применения методики IPOM в первой группе – с 7,5 до 3 баллов (р&lt;0,05). Кратчайший срок возвращения спортсмена к тренировкам составляет 3 недели после хирургического лечения спортивной грыжи при лапароскопической пластике задней стенки пахового канала по методике ТАРР с установкой самофиксирующей сетки. В исследовании сделан сравнительный анализ результатов лапароскопических хирургических вмешательств и определена оптимальная тактика выбора хирургического лечения спортивной грыжи у футболистов.Мета роботи: визначити оптимальну тактику вибору хірургічного лікування спортивної грижі у футболістів. Матеріали і методи. Проведено аналіз результатів хірургічного лікування 36 футболістів професійних та аматорських клубів віком від 18 до 34 років із діагнозом&nbsp; спортивна грижа, які перебували в хірургічному відділенні КМКЛ № 3 впродовж 2014–2019 рр. Хворих було розподілено на дві групи дослідження залежно від методики хірургічного втручання. В першій групі виділено дві підгрупи, до першої підгрупи хворих увійшли 10 футболістів, яким виконували лапароскопічну інтраперитонеальну герніо­алопластику за методикою IPOM. До другої підгрупи увійшли 8 футболістів, яким виконували лапароскопічну інтраперитонеальну герніоалопластику за методикою IPOM із субдермальним ушиванням внутрішніх пахових кілець. До другої групи увійшли 18 футболістів, яким виконували лапароскопічну трансабдомінальну преперитонеальну герніоалопластику за методикою TAPP. Для оцінки показників якості життя застосовували опитувальник The Copenhagen Hip and Groin Outcome Score (HAGOS) та Eura HS Quality of Life score (Eura HS-QoL у модифікації). Результати досліджень та їх обговорення. При аналізі показників за шкалою HAGOS якість життя до операції не відрізнялась в обох групах дослідження, тоді як після проведення хірургічного лікування значно підвищилась у другій групі з 47 до 96 балів та в першій групі з 45 до 80 балів (р&lt;0,05). Також в другій групі встановлено достовірне зменшення больового синдрому в пахвинній ділянці після лапароскопічної герніоалопластики за методикою ТАРР з 8 балів до 2 балів за шкалою ВАШ і після застосування методики IPOM у першій групі з 7,5 до 3 балів (р&lt;0,05). Найкоротший термін повернення спортсмена до тренувань становить 3 тижні після хірургічного лікування спортивної грижі виявлено при лапароскопічній пластиці задньої стінки пахового каналу за методикою ТАРР зі встановленням самофіксуючої сітки. У дослідженні проведено порівняльний аналіз результатів лапароскопічних хірургічних втручань та визначено оптимальну тактику вибору хірургічного лікування спортивної грижі у футболістів