Rotation sets of billiards with one obstacle

We investigate the rotation sets of billiards on the $m$-dimensional torus with one small convex obstacle and in the square with one small convex obstacle. In the first case the displacement function, whose averages we consider, measures the change of the position of a point in the universal covering of the torus (that is, in the Euclidean space), in the second case it measures the rotation around the obstacle. A substantial part of the rotation set has usual strong properties of rotation sets

All-dielectric magnetic metasurface for advanced light control in dual polarizations combined with high-Q resonances

Nanostructured magnetic materials provide an efficient tool for light manipulation on sub-nanosecond and sub-micron scales, and allow for the observation of the novel effects which are fundamentally impossible in smooth films. For many cases of practical importance, it is vital to observe the magneto-optical intensity modulation in a dual-polarization regime. However, the nanostructures reported on up to date usually utilize a transverse Kerr effect and thus provide light modulation only for p-polarized light. We present a concept of a transparent magnetic metasurface to solve this problem, and demonstrate a novel mechanism for magneto-optical modulation. A 2D array of bismuth-substituted iron-garnet nanopillars on an ultrathin iron-garnet slab forms a metasurface supporting quasi-waveguide mode excitation. In contrast to plasmonic structures, the all-dielectric magnetic metasurface is shown to exhibit much higher transparency and superior quality-factor resonances, followed by a multifold increase in light intensity modulation. The existence of a wide variety of excited mode types allows for advanced light control: transmittance of both p- and s-polarized illumination becomes sensitive to the medium magnetization, something that is fundamentally impossible in smooth magnetic films. The proposed metasurface is very promising for sensing, magnetometry and light modulation applications

Microstructure and mechanical properties of V-4Ti-4Cr alloy as a function of the chemical heat treatment regimes

The regularities of the formation of a heterophase structure and mechanical properties of V–4Ti–4Cr alloy as a function of thermomechanical and chemical heat treatments are studied. The regimes of thermomechanical treatment which provide the formation of a heterophase structure with a homogeneous volume distribution of oxycarbonitride nanoparticles with a size of about 10 nm and an increase in the volume content and thermal stability of this phase and which provide an increase in the temperature of alloy recrystallization are developed. The formation of the heterophase structure results in a substantial (up to 70%) increase in the short-term high-temperature strength of the alloy at T = 800°C. The increase in the strength is achieved while keeping a rather high level of plasticity

Host–Guest Chemistry in Boron Nitride Nanotubes: Interactions with Polyoxometalates and Mechanism of Encapsulation

Boron nitride nanotubes (BNNTs) are an emerging class of molecular container offering new functionalities and possibilities for studying molecules at the nanoscale. Herein, BNNTs are demonstrated as highly effective nanocontainers for polyoxometalate (POM) molecules. The encapsulation of POMs within BNNTs occurs spontaneously at room temperature from an aqueous solution, leading to the self-assembly of a POM@BNNT host−guest system. Analysis of the interactions between the host-nanotube and guest-molecule indicate that Lewis acid−base interactions between W=O groups of the POM (base) and B-atoms of the BNNT lattice (acid) likely play a major role in driving POM encapsulation, with photoactivated electron transfer from BNNTs to POMs in solution also contributing to the process. The transparent nature of the BNNT nanocontainer allows extensive investigation of the guest-molecules by photoluminescence, Raman, UV−vis absorption, and EPR spectroscopies. These studies revealed considerable energy and electron transfer processes between BNNTs and POMs, likely mediated via defect energy states of the BNNTs and resulting in the quenching of BNNT photoluminescence at room temperature, the emergence of new photoluminescence emissions at cryogenic temperatures (<100 K), a photochromic response, and paramagnetic signals from guest-POMs. These phenomena offer a fresh perspective on host−guest interactions at the nanoscale and open pathways for harvesting the functional properties of these hybrid systems

НЕПОСРЕДСТВЕННЫЕ И ОТДАЛЕННЫЕ РЕЗУЛЬТАТЫ МИНИИНВАЗИВНОГО ПРОТЕЗИРОВАНИЯ АОРТАЛЬНОГО КЛАПАНА: ОДНОЦЕНТРОВОЕ РЕТРОСПЕКТИВНОЕ ИССЛЕДОВАНИЕ

HighlightsWe have conducted a retrospective analysis of patients who underwent minimally invasive aortic valve replacement, and evaluated immediate and long-term results of the surgery. AbstractAim. To study the immediate and long-term results of minimally invasive aortic valve (AV) replacement.Methods. The retrospective study included 208 patients with AV stenosis undergoing minimally invasive aortic valve replacement in the period from 2010 to 2019. The ratio of men to women was 1:1. The mean age of the patients was 63 (58–68) years old, with the minimum age being 29 years and the maximum being 81 years. The median follow-up period was 45.5 (11–68) months. Endpoints were as follows: hospital mortality, postoperative complications, long-term outcome (long-term survival, freedom from reoperation). Inclusion criteria were as follows: patients aged 18 years and older undergoing minimally invasive aortic valve replacement. Exclusion criteria were as follows: AVNeo, Ross procedure and AV replacement with aortic homograft, combined interventions (except for intervention on the ascending aorta), and standard access site.Results. The majority of patients (199 (95.7%) underwent “J”-shaped ministernotomy through the III-IV intercostal space. As a part of the combined intervention, ascending aorta replacement was performed in 6 (2.9%) patients. The duration of cardiopulmonary bypass and aortic cross-clamping was 91 (78–106) min and 68 (60–78) min, respectively. Due to conduction disorders, implantation of a pacemaker was performed in 5 (2.4%) patients, stroke was diagnosed in 1 (0.5%) patient, resternotomy for bleeding was performed in 4 (1.9%) patients, cardiac tamponade in 2 (1 %) patients, sternal infection was found in 1 (0.5%) patient. There were no complications such as AKI, perioperative MI, or hospital mortality in any patient. Five- and ten-year survival after surgical treatment of patients was 88.2% and 80.5%, respectively. Five- and ten-year freedom from reoperation on AV was 96.2% and 96.2%.Conclusions. Minimally invasive AV replacement is a measurable procedure with negligible complication rates. Minimally invasive aortic valve replacement has shown its effectiveness in the long-term period with acceptable rates of survival and freedom from reoperation.Основные положенияПроведен ретроспективный анализ больных, перенесших операцию на аортальном клапане путем миниинвазивного доступа.Оценены непосредственные и отдаленные результаты миниинвазивного вмешательства на аортальном клапане. Цель. Изучить непосредственные и отдаленные результаты операции на аортальном клапане (АК) с применением миниинвазивного доступа. Материал и методы. В ретроспективное исследование включены 208 пациентов с поражением АК, которым с 2010 по 2019 г. выполнено миниинвазивное протезирование. Соотношение мужчин и женщин составило 1:1. Средний возраст больных составил 63 (58–68) года, при этом минимальный возраст был 29 лет, а максимальный – 81. Медиана периода наблюдения составила 45,5 (11–68) мес. Конечные точки: госпитальная летальность, постоперационные осложнения, отдаленные результаты (отдаленная выживаемость, свобода от реоперации). Критерии включения: пациенты 18 лет и старше, оперированные путем миниинвазивного доступа. Критерии исключения: операции AVNeo и Росса, протезирование АК аортальным гомографтом, комбинированные операции за исключением вмешательств на восходящей аорте, повторные вмешательства, операции через стандартный доступ.Результаты. Большинству больных, 199 (95,7%), выполнена J-образная министернотомия через III–IV межреберье. В качестве комбинированного вмешательства протезирование аорты выполнено 6 (2,9%) пациентам. Длительность искусственного кровообращения и ишемии миокарда составила 91 (78–106) мин и 68 (60–78) мин соответственно. В связи с нарушением проводимости 5 (2,4%) больным имплантирован постоянный электрокардиостимулятор, инсульт диагностирован у 1 (0,5%) пациента, рестернотомия по поводу кровотечения выполнена 4 (1,9%) больным, тампонада сердца возникла у 2 (1%) пациентов, стернальная инфекция – у 1 (0,5%). Таких осложнений, как острое почечное повреждение, периоперационный инфаркт миокарда и госпитальная летальность, не зарегистрировано ни у одного пациента. Пяти- и десятилетние выживаемость составила 88,2 и 80,5%, свобода от реоперации на АК – 96,2% и 96,2% соответственно.Заключение. Миниинвазивное протезирование АК можно считать безопасной процедурой с низкой частотой осложнений. Данный тип вмешательства показал удовлетворительные выживаемость и свободу от реоперации в отдаленном периоде

Observation of Cabibbo-suppressed two-body hadronic decays and precision mass measurement of the Ωc0\Omega_{c}^{0} baryon

The first observation of the singly Cabibbo-suppressed $\Omega_{c}^{0}\to\Omega^{-}K^{+}$ and $\Omega_{c}^{0}\to\Xi^{-}\pi^{+}$ decays is reported, using proton-proton collision data at a centre-of-mass energy of $13\,{\rm TeV}$, corresponding to an integrated luminosity of $5.4\,{\rm fb}^{-1}$, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be $\frac{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}K^{+})}{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}\pi^{+})}=0.0608\pm0.0051({\rm stat})\pm 0.0040({\rm syst})$, $\frac{\mathcal{B}(\Omega_{c}^{0}\to\Xi^{-}\pi^{+})}{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}\pi^{+})}=0.1581\pm0.0087({\rm stat})\pm0.0043({\rm syst})\pm0.0016({\rm ext})$. In addition, using the $\Omega_{c}^{0}\to\Omega^{-}\pi^{+}$ decay channel, the $\Omega_{c}^{0}$ baryon mass is measured to be $M(\Omega_{c}^{0})=2695.28\pm0.07({\rm stat})\pm0.27({\rm syst})\pm0.30({\rm ext})\,{\rm MeV}/c^{2}$, improving the precision of the previous world average by a factor of four.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-011.html (LHCb public pages

Observation of the doubly charmed baryon decay Ξcc++→Ξc′+π+

The Ξcc++→Ξc′+π+ decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb−1. The Ξcc++→Ξc′+π+ decay is reconstructed partially, where the photon from the Ξc′+→Ξc+γ decay is not reconstructed and the pK−π+ final state of the Ξc+ baryon is employed. The Ξcc++→Ξc′+π+branching fraction relative to that of the Ξcc++→Ξc+π+ decay is measured to be 1.41 ± 0.17 ± 0.10, where the first uncertainty is statistical and the second systematic. [Figure not available: see fulltext.