[Morphological features of an optic nerve in premature infants according to the optical coherence tomography data]. / Morfologicheskie osobennosti zritel'nogo nerva u nedonoshennykh detei po dannym opticheskoi kogerentnoi tomografii.

OBJECTIVE: To assess the morphological state of the visual analyzer in premature infants in long-term. MATERIAL AND METHODS: We examined 40 premature children (74 eyes) aged 10.3±2.92 years (gestational age (GA) 25-34 weeks, birth weight (BW) 690-2700 g). Twenty mature children (40 eyes), aged 10.8±3.05 years, were examined as a control group. The children underwent standard ophthalmologic examination, optical coherence tomography (OCT) and recording of visual evoked potentials (VEP). RESULTS: The thickness of retinal nerve fiber layer (RNFL) is less in preterm infants than in term infants, regardless of retinopathy of prematurity (ROP) and refraction (p<0.05). Thickness loss has an inverse proportion with the degree of hypoxic-ischemic encephalopathy (HIE) and intraventricular hemorrhage (IVH) (p<0.05). Retinal thickness in fovea is significantly greater in preterm infants and has a direct proportionality with the degree of IVH and the number of days on artificial lung ventilation (p<0.05). Moderate organic changes were detected in conduction pathways in 43.08% of premature infants according to VEP data. CONCLUSION: The use of OCT and recording of VEP may improve the quality of comprehensive neuro-ophthalmologic diagnosis in preterm infants. The thickness loss of RNFL can be expected in premature infants with HIE and IVH.

Spin Light Emitting Diode Based on Exciton Fine Structure Tuning in Quantum Dots.

We propose a concept of quantum dot based light emitting diode that produces circularly polarized light without magnetic contacts due to the hyperfine interaction at the crossing of the exciton levels in a weak magnetic field. The electroluminescence circular polarization degree can reach 100%. The concept is compatible with the micropillar cavities, which allows for the generation of single circularly polarized photons. Second order photon correlation function includes information about the nuclear spin dynamics in the quantum dot, and the nuclear spin state can be purified by the quantum measurement backaction.

THE INCIDENCE OF SPORTS INJURIES AMONG SCHOOL-AGED CHILDREN AND ADOLESCENTS.

It is estimated that approximately one in ten school-aged children experience sports-related injuries annually. These injuries are most common at 12 years of age. Boys are more likely to get injured and more likely to get seriously injured than girls. The probability of injury is greater in contact or high-impact sports, with American soccer accounting for the largest number of injuries, followed by wrestling, basketball, soccer, and baseball. In certain sports, such as horseback riding, women are four times more likely to sustain injuries. The presented literature review details the incidence of various sports-related injuries in adolescents. Sports-related injuries observed in children under the age of 10 are nonspecific and include contusions, mild sprains, and fractures of the extremities, most commonly Salter-Harris fractures (growth plate fractures) or plastic fractures. In young athletes, sports-related injuries of the ligaments or muscles, as well as spinal or head injuries, are rare. This is particularly true during puberty, where growth plate fractures and musculoskeletal injuries occur more frequently.

The squeezed dark nuclear spin state in lead halide perovskites.

Coherent many-body states are highly promising for robust quantum information processing. While far-reaching theoretical predictions have been made for various implementations, direct experimental evidence of their appealing properties can be challenging. Here, we demonstrate optical manipulation of the nuclear spin ensemble in the lead halide perovskite semiconductor FAPbBr3 (FA = formamidinium), targeting a long-postulated collective dark state that is insensitive to optical pumping after its build-up. Via optical orientation of localized hole spins we drive the nuclear many-body system into this entangled state, requiring a weak magnetic field of only a few milli-Tesla strength at cryogenic temperatures. During its fast establishment, the nuclear polarization along the optical axis remains small, while the transverse nuclear spin fluctuations are strongly reduced, corresponding to spin squeezing as evidenced by a strong violation of the generalized nuclear squeezing-inequality with ξs < 0.5. The dark state corresponds to an ~35-body entanglement between the nuclei. Dark nuclear spin states can be exploited to store quantum information benefiting from their long-lived many-body coherence and to perform quantum measurements with a precision beyond the standard limit.

Optical Orientation of Excitons in a Longitudinal Magnetic Field in Indirect-Band-Gap (In,Al)As/AlAs Quantum Dots with Type-I Band Alignment.

Exciton recombination and spin dynamics in (In,Al)As/AlAs quantum dots (QDs) with indirect band gap and type-I band alignment were studied. The negligible (less than 0.2 µeV) value of the anisotropic exchange interaction in these QDs prevents the mixing of the excitonic basis states and makes the formation of spin-polarized bright excitons possible under quasi-resonant, circularly polarized excitation. The recombination and spin dynamics of excitons are controlled by the hyperfine interaction between the electron and nuclear spins. A QD blockade by dark excitons was observed in the magnetic field, that eliminates the impact of nuclear spin fluctuations. A kinetic model which accounts for the population dynamics of the bright and dark exciton states as well as for the spin dynamics was developed to quantitatively describe the experimental data.

THE STRESS IN THE ACL, ACL GRAFT, AND OTHER JOINT ELEMENTS WHILE WEIGHT-BEARING IN FULL EXTENSION DEPENDING ON THE POSTERIOR TIBIAL SLOPE.

The safety of early weight bearing after anterior cruciate ligament (ACL) reconstruction and the degree of posterior tibial slope (PTS) impact on ACL and ACL graft are still uncertain due to the limitations of previous studies. The study aimed to evaluate the effect of PTS change on ACL and ACL graft stress. We created the complex multicomponent static models of physiologically normal knee joint, taking into account the different PTS, the ligaments of the knee joint, including the ALL, articular cartilage, and menisci, literature data on muscle tension also with double-bundle ACL and single-bundle ACL graft to determine deformations and stress on the anatomical elements of the joint at a qualitatively new level. Stress in the knee structures was assessed using the finite element method separately with a 6 mm diameter double-bundle normal ACL and an 8 mm single-bundle ACL graft for the two variants of the tibial plateau slope: 5° and 13.9°. Raising PTS from 5° to 13.9° increases stress in the ACL by 1.29 - 1.45 times and in the single-bundle ACL graft by 1.75 - 1.81 times in the upright position with knees in full extension. Stress in ALL increases with higher PTS by 1.58-2.00 times in the knee joint with double-bundle ACL and 1.93-2.02 times in the knee joint with single-bundle ACL graft while weight bearing in full extension. Increasing the PTS angle from 5° to 13.9° with healthy ACL stress in the meniscus increases by 1.05 - 1.34 times, and with a single-bundle ACL graft - by 2.04 - 2.30 times. Replacing the double-bundle ACL with the single-bundle ACL graft also causes an increase in its stress compared to intact ACL under all studied conditions. Increased PTS and ACL reconstruction significantly increase stress in most knee anatomical elements while weight bearing in full extension. Even with a total weight of up to 150 kg, the critical value of stress for the rupture of the ACL graft from a one-time load is not achieved even after reducing its breaking load in 6 weeks. In the early postoperative period, the weakest link is the fixation of the graft with the interference screw. Cyclic load on the fully extended knee (regular walking) can provoke slipping out of the graft from under the interference screw.

Optical measurement of electron spins in quantum dots: quantum Zeno effects.

We describe theoretically the effects of the quantum back action under the continuous optical measurement of electron spins in quantum dots. We consider the system excitation by elliptically polarized light close to the trion resonance, which allows for simultaneous spin orientation and measurement. We microscopically demonstrate that the nuclei-induced spin relaxation can be both suppressed and accelerated by the continuous spin measurement due to the quantum Zeno and anti-Zeno effects, respectively. Our theoretical predictions can be directly compared with the future experimental results and straightforwardly generalized for pump-probe experiments.

Spin Noise in Birefringent Media.

It is known that linear birefringence of the medium essentially hinders measuring the Faraday effect. For this reason, optically anisotropic materials have never been considered as objects of the Faraday-rotation-based spin noise spectroscopy. We show, both theoretically and experimentally, that strong optical anisotropy that may badly suppress the regular Faraday rotation of the medium, practically does not affect the measurement of the spatially uncorrelated spin fluctuations. We also show that the birefringent media provide additional opportunity to measure spatial spin correlations. Results of the experimental measurements of the spin-noise spectra performed on Nd^{3+} ions in the uniaxial crystal matrices well agree with the theory.

Current-induced hole spin polarization in a quantum dot via a chiral quasi bound state.

We put forward a mechanism for the current-induced spin polarization in semiconductor heterostructures, which is based on the complex structure of the valence band. It takes place for a light hole in a quantum dot side-coupled to a quantum wire with heavy holes. In stark contrast with the traditional mechanisms based on the linear in momentum spin-orbit coupling, an exponentially small bias applied to this structure is enough to create the 100% spin polarization in the quantum dot. Microscopically, this effect is related to the formation of the chiral quasi bound states and the spin-dependent tunneling of holes from the quantum wire to the quantum dot. This new concept is equally valid for the GaAs-, Si- and Ge-based nanostructures.

De novo assembly and analysis of the transcriptome of the Siberian wood frog Rana amurensis.

The Siberian wood frog Rana amurensis Boulenger, 1886 is the most hypoxia-tolerant amphibian. It can survive for several months in an almost complete absence of oxygen. Little is known about the mechanisms of this remarkable resilience, in part because studies of amphibian genomes are impeded by their large size. To make the Siberian wood frog more amenable for genetic analysis, we performed transcriptome sequencing and de novo assembly for the R. amurensis brain under hypoxia and normoxia, as well as for the normoxic heart. In order to build a de novo transcriptome assembly of R. amurensis, we utilized 125-bp paired-end reads obtained from the brain under normoxia and hypoxia conditions, and from the heart under normoxia. In the transcriptome assembled from about 100,000,000 reads, 81.5 % of transcripts were annotated as complete, 5.3 % as fragmented, and 13.2 % as missing. We detected 59,078 known transcripts that clustered into 22,251 genes; 11,482 of them were assigned to specific GO categories. Among them, we found 6696 genes involved in protein binding, 3531 genes involved in catalytic activity, and 576 genes associated with transporter activity. A search for genes encoding receptors of the most important neurotransmitters, which may participate in the response to hypoxia, resulted in a set of expressed receptors of dopamine, serotonin, GABA, glutamate, acetylcholine, and norepinephrine. Unexpectedly, no transcripts for histamine receptors were found. The data obtained in this study create a valuable resource for studying the mechanisms of hypoxia tolerance in the Siberian wood frog, as well as for amphibian studies in general.

Otolaryngologist Characteristics and Outlier Use of Balloon Sinuplasty in the Medicare Population.

OBJECTIVE: Balloon sinuplasty (BSP) is associated with varied practice patterns. This study sought to identify otolaryngologist characteristics associated with BSP utilization. STUDY DESIGN: Retrospective analysis of Medicare claims data and the National Physician Compare database. METHODS: Outlier otolaryngologists were compared to non-outliers. Otolaryngologist characteristics included sex, practice size, geographic setting, years of experience, procedure setting, 10 or fewer endoscopic sinus surgeries per year for 3 or more years, and high number of services per unique Medicare beneficiary. Outlier status was defined as performing an annual total of balloon procedures of 2 standard deviations (SDs) above the mean for all otolaryngologists in the same year. RESULTS: Between January 2012 and December 2017, 1,408 otolaryngologists performed 101,662 endoscopic sinus surgeries and 97,680 BSP procedures. Sixty-six outlier otolaryngologists (4.7%) accounted for 44.3% of all BSP procedures. Outlier status was associated with practice size of 10 or fewer individual providers (OR, 5.15; 95% CI, 2.73-9.74; P < .001), performance of 10 or fewer total endoscopic sinus surgeries per year for 3 or more years (OR, 3.90; 95% CI, 1.59-9.57; P = .003), and high number of overall services per beneficiary (OR 6.70; 95% CI, 1.19-37.84; P = .031). Provider sex, years of experience, and geographic setting were not associated with outlier status. CONCLUSION: Outlier BSP patterns are associated with a few otolaryngologists who are more likely to be identified in small practices and record low numbers of endoscopic surgeries. Although BSP is an appropriate and effective tool, identification of outlier patterns may help to facilitate peer-to-peer counsel. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:1340-1345, 2022.

Nuclear Spin Dynamics, Noise, Squeezing, and Entanglement in Box Model.

We obtain a compact analytical solution for the nonlinear equation for the nuclear spin dynamics in the central spin box model in the limit of many nuclear spins. The total nuclear spin component along the external magnetic field is conserved and the two perpendicular components precess or oscillate depending on the electron spin polarization, with the frequency, determined by the nuclear spin polarization. As applications of our solution, we calculate the nuclear spin noise spectrum and describe the effects of nuclear spin squeezing and many body entanglement in the absence of a system excitation.

A checklist of bat-associated macronyssid mites (Acari: Gamasina: Macronyssidae) of Russia, with new host and geographical records.

The family Macronyssidae (Acari: Mesostigmata) comprises mostly obligate blood-sucking ectoparasites of bats (Mammalia: Chiroptera) and some other animals, such as small mammals, reptiles and birds. Here, we document and curate previously known data, and, based on our extensive survey, provide this article of bat-associated macronyssid mites of the Russian Federation. We record a total of 24 mite species belonging to 4 genera (Ichoronyssus, Macronyssus, Steatonyssus, and Cryptonyssus). Twenty-seven new host-parasite associations are reported. In addition, were provide data on five major Russian regions, for which bat-associated mite records were lacking.

Ectoparasites and Pathogens of Kuhl's Pipistrelle Pipistrellus kuhlii (Kuhl, 1817) (Chiroptera: Vespertilionidae): Our Own and Published Data Review.

Here we report the results of our own survey and literary published data on the ectoparasite fauna and pathogens of the alien bat species, the Kuhl's pipistrelle Pipistrellus kuhlii (Kuhl, 1817) (Chiroptera: Vespertilionidae). This bat is a host of 36 species of parasitic mites, ticks and insects (including accidental findings) and 13 species of pathogens (protozoa, bacteria, viruses). The flea Ischnopsyllus variabilis is re-corded on this host for the first time. We have found that outside of the host ancestral range, the core of the bat parasite fauna is significantly different due to the loss of host species-specific ectoparasites. Particularly, in Russia, only 6 species of parasitic arthropods have been recorded for Kuhl's pipistrelle and all of them are host genus-specific. At the same time, the features of ecology and occasional finds of extrinsic parasites allow to suggest that P. kuhlii has wide contacts with animals which are the reservoirs of zoonotic infec-tions, that in combination with the fact of isolation of several pathogens from this species (including two coronaviruses) points to a possible medical importance of Kuhl's pipistrelle.

Dynamic Polarization of Electron Spins Interacting with Nuclei in Semiconductor Nanostructures.

We suggest a new spin orientation mechanism for localized electrons: dynamic electron spin polarization provided by nuclear spin fluctuations. The detrimental effect of nuclear spin fluctuations can be harnessed and employed to provide angular momentum for the electrons via the hyperfine interaction in a weak magnetic field. For this, the sample is illuminated by an unpolarized light, which directly polarizes neither the electrons nor the nuclei. We predict that, for the electrons bound in localized excitons, 100% spin polarization can be reached in longitudinal magnetic fields of a few millitesla. The proof of principle experiment is performed on momentum-indirect excitons in (In,Al)As/AlAs quantum dots, where in a magnetic field of 17 mT the electron spin polarization of 30% is measured.

Unraveling the Topological Phase of ZrTe_{5} via Magnetoinfrared Spectroscopy.

For materials near the phase boundary between weak and strong topological insulators (TIs), their band topology depends on the band alignment, with the inverted (normal) band corresponding to the strong (weak) TI phase. Here, taking the anisotropic transition-metal pentatelluride ZrTe_{5} as an example, we show that the band inversion manifests itself as a second extremum (band gap) in the layer stacking direction, which can be probed experimentally via magnetoinfrared spectroscopy. Specifically, we find that the band anisotropy of ZrTe_{5} features a slow dispersion in the layer stacking direction, along with an additional set of optical transitions from a band gap next to the Brillouin zone center. Our work identifies ZrTe_{5} as a strong TI at liquid helium temperature and provides a new perspective in determining band inversion in layered topological materials.

Crystalline and amorphous calcium carbonate as structural components of the Calappa granulata exoskeleton.

The exoskeleton of crustaceans consists of chitin biopolymers where the embedded inorganic biominerals, mainly CaCO3, affect strongly its mechanical properties. Raman and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopies and Transmission Electron Microscopy (TEM) are applied to investigate the CaCO3 structure in various parts of the Calappa granulata crab exoskeleton. The shape of the main Raman peak of CaCO3 reveals the presence of two phases which are identified as calcite and amorphous calcium carbonate (ACC). The relative concentration of the two phases in various parts of the exoskeleton is determined from the area ratio under the corresponding peaks. The results of the Ca L3,2-edge NEXAFS analysis are in line with the Raman findings, since the energy separation of peaks that appear in the lower frequency region of the main L2 and L3 peaks due to crystal field splitting, is directly related to the percentage of the ACC phase in the total CaCO3 mineral content. The C K-edge spectra are used for the determination of the extent of calcification of the exoskeleton. Furthermore, dark and bright field TEM images reveal the presence of nanocrystallites with an average size of 20 nm. The structure of the nanocrystallites, as derived from the Selected Area Electron Diffraction patterns, is calcite. The results suggest that ACC plays a structural role in the exoskeleton of Calappa granulata.

Strongly Confined Excitons in GaN/AlN Nanostructures with Atomically Thin GaN Layers for Efficient Light Emission in Deep-Ultraviolet.

Fascinating optical properties governed by extremely confined excitons have been so far observed in 2D crystals like monolayers of transition metal dichalcogenides. These materials, however, are limited for production by epitaxial methods. Besides, they are not suitable for the development of optoelectronics for the challenging deep-ultraviolet spectral range. Here, we present a single monolayer of GaN in AlN as a heterostructure fabricated by molecular beam epitaxy, which provides extreme 2D confinement of excitons, being ideally suited for light generation in the deep-ultraviolet. Optical studies in the samples, supplemented by a group-theory analysis and first-principle calculations, make evident a giant enhancement of the splitting between the dark and bright excitons due to short-range electron-hole exchange interaction that is a fingerprint of the strongly confined excitons. The practical significance of our results is in the observation of the internal quantum yield of the room-temperature excitonic emission as high as ∼75% at 235 nm.

Surface deep profile synchrotron studies of mechanically modified top-down silicon nanowires array using ultrasoft X-ray absorption near edge structure spectroscopy.

Atomic, electronic structure and composition of top-down metal-assisted wet-chemically etched silicon nanowires were studied by synchrotron radiation based X-ray absorption near edge structure technique. Local surrounding of the silicon and oxygen atoms in silicon nanowires array was studied on as-prepared nanostructured surfaces (atop part of nanowires) and their bulk part after, first time applied, in-situ mechanical removal atop part of the formed silicon nanowires. Silicon suboxides together with disturbed silicon dioxide were found in the composition of the formed arrays that affects the electronic structure of silicon nanowires. The results obtained by us convincingly testify to the homogeneity of the phase composition of the side walls of silicon nanowires and the electronic structure in the entire length of the nanowire. The controlled formation of the silicon nanowires array may lead to smart engineering of its atomic and electronic structure that influences the exploiting strategy of metal-assisted wet-chemically etched silicon nanowires as universal matrices for different applications.

DTL-RnB: Algorithms and Tools for Summarizing the Space of DTL Reconciliations.

Phylogenetic tree reconciliation is an important technique for reconstructing the evolutionary histories of species and genes and other dependent entities. Reconciliation is typically performed in a maximum parsimony framework and the number of optimal reconciliations can grow exponentially with the size of the trees, making it difficult to understand the solution space. This paper demonstrates how a small number of reconciliations can be found that collectively contain the most highly supported events in the solution space. While we show that the formal problem is NP-complete, we give a approximation algorithm, experimental results that indicate its effectiveness, and the new DTL-RnB software tool that uses our algorithms to summarize the space of optimal reconciliations (www.cs.hmc.edu/dtlrnb).