Subbarrier absorption in a stationary superlattice

The calculation of the interband absorption coefficient was carried out in the classical case, when the frequency of light was assumed to bind two miniband subbarrier states of different bands. The influence of two dimensional Mott excitons on this absorption was studied and a comparison was made with the experiment. All of these considerations were done taking into account the photon wave vector (the phase spatial heterogeneity). The basic traits of the energy spectra of superlattice semiconductors, their kinetic and optical properties, and possible means of electromagnetic wave intensification were examined. By the density matrix method, a theory of electrical and electromagnetic properties of superlattices was suggested

Origin of second-harmonic generation in the incommensurate phase of K2SeO4

We show that a ferroelectric phase transition takes place in the incommensurate phase of the K2SeO4 crystal. The ferroelectric character of the IC phase explains the second-harmonic generation observed in the corresponding temperature range.Comment: 5 pages, 1 figur

Effect of CPAP therapy on left atrial remodeling in patients with paroxysmal atrial fibrillation and obstructive sleep apnea undergoing pulmonary vein isolation

Aim. To study the isolated effect of obstructive sleep apnea (OSA) on left atrial (LA) remodeling in patients with paroxysmal atrial fibrillation (AF) who underwent pulmonary vein (PV) ablation and concomitant severe and moderate OSA.Material and methods. A subanalysis of echocardiographic data was performed in 50 patients with paroxysmal AF and moderate/severe OSA who underwent PV isolation and were followed up for 12 months (main group, 33; control group, 17). The clinical efficacy of catheter ablation was assessed after the end of the threemonth blind period. The following echocardiographic parameters were included in the subanalysis: anterior-posterior LA dimension, LA volume, LA volume index (LAVI), and pulmonary artery systolic pressure (PASP).Results. After 12 months, the control group showed a significant increase in the anterior-posterior LA dimension (40,5 (40-42) mm vs 42 (40-45) mm, p=0,037), LA volume (68,5 (58-74,5) ml vs 69 (63-89) ml, p=0,006), LAVI (35,0 (29-37) ml/m2 vs 35,5 (32-41,5) ml/m2, p=0,005) and PASP (27 (25-30) vs 30 (29-33), p=0,004). Intragroup analysis of patients not receiving continuous positive airway pressure (CPAP) therapy and without recurrent AF did not reveal significant changes in LA size (anterior-posterior LA dimension — 40 (40-42) mm vs 40 (40- 41) mm, p=0,317; LA volume — 63 (58-71) ml vs 64 (61-69) ml, p=0,509; LAVI — 32 (29-36) ml/m2 vs 33 (31-34) ml2, p=0,509).Conclusion. In patients with paroxysmal AF and concomitant moderate to severe OSA who underwent AF catheter treatment, the absence of CPAP therapy is not associated with a significant increase in the linear and volume LA dimensions in the absence of AF recurrence

Bremsstrahlung Suppression due to the LPM and Dielectric Effects in a Variety of Materials

The cross section for bremsstrahlung from highly relativistic particles is suppressed due to interference caused by multiple scattering in dense media, and due to photon interactions with the electrons in all materials. We present here a detailed study of bremsstrahlung production of 200 keV to 500 MeV photons from 8 and 25 GeV electrons traversing a variety of target materials. For most targets, we observe the expected suppressions to a good accuracy. We observe that finite thickness effects are important for thin targets.Comment: 52 pages, 13 figures (incorporated in the revtex LaTeX file

The regulatory subunit of PKA-I remains partially structured and undergoes β-aggregation upon thermal denaturation

Background: The regulatory subunit (R) of cAMP-dependent protein kinase (PKA) is a modular flexible protein that responds with large conformational changes to the binding of the effector cAMP. Considering its highly dynamic nature, the protein is rather stable. We studied the thermal denaturation of full-length RIα and a truncated RIα(92-381) that contains the tandem cyclic nucleotide binding (CNB) domains A and B. Methodology/Principal Findings: As revealed by circular dichroism (CD) and differential scanning calorimetry, both RIα proteins contain significant residual structure in the heat-denatured state. As evidenced by CD, the predominantly α-helical spectrum at 25°C with double negative peaks at 209 and 222 nm changes to a spectrum with a single negative peak at 212-216 nm, characteristic of β-structure. A similar α→β transition occurs at higher temperature in the presence of cAMP. Thioflavin T fluorescence and atomic force microscopy studies support the notion that the structural transition is associated with cross-β-intermolecular aggregation and formation of non-fibrillar oligomers. Conclusions/Significance: Thermal denaturation of RIα leads to partial loss of native packing with exposure of aggregation-prone motifs, such as the B' helices in the phosphate-binding cassettes of both CNB domains. The topology of the β-sandwiches in these domains favors inter-molecular β-aggregation, which is suppressed in the ligand-bound states of RIα under physiological conditions. Moreover, our results reveal that the CNB domains persist as structural cores through heat-denaturation. © 2011 Dao et al

Single-cell Atlas of common variable immunodeficiency shows germinal center-associated epigenetic dysregulation in B-cell responses

Common variable immunodeficiency (CVID), the most prevalent symptomatic primary immunodeficiency, displays impaired terminal B-cell differentiation and defective antibody responses. Incomplete genetic penetrance and ample phenotypic expressivity in CVID suggest the participation of additional pathogenic mechanisms. Monozygotic (MZ) twins discordant for CVID are uniquely valuable for studying the contribution of epigenetics to the disease. Here, we generate a single-cell epigenomics and transcriptomics census of naïve-to-memory B cell differentiation in a CVID-discordant MZ twin pair. Our analysis identifies DNA methylation, chromatin accessibility and transcriptional defects in memory B-cells mirroring defective cell-cell communication upon activation. These findings are validated in a cohort of CVID patients and healthy donors. Our findings provide a comprehensive multi-omics map of alterations in naïve-to-memory B-cell transition in CVID and indicate links between the epigenome and immune cell cross-talk. Our resource, publicly available at the Human Cell Atlas, gives insight into future diagnosis and treatments of CVID patients

Moving liquids with light: Photoelectrowetting on semiconductors

Liquid transport in microchip-based systems is important in many areas such as Laboratory-on-a-chip, Microfluidics and Optofluidics. Actuation of liquids in such systems is usually achieved using either mechanical displacement11 or via energy conversion e.g. electrowetting which modifies wetting. However, at the moment there is no clear way of actuating a liquid using light. Here, by linking semiconductor physics and wetting phenomenon a brand new effect "photoelectrowetting" is demonstrated for a droplet of conducting liquid resting on an insulator-semiconductor stack. Optical generation of carriers in the space-charge region of the underlying semiconductor alters the capacitance of the insulator-semiconductor stack; the result of this is a modification of the wetting contact angle of the droplet upon illumination. The effect is demonstrated using commercial silicon wafers, both n- and p-type having a doping range spanning four orders of magnitude (6\times1014-8\times1018 cm-3), coated with a commercial fluoropolymer insulating film (Teflon\textregistered). Impedance measurements confirm that the observations are semiconductor space-charge related effects. The impact of the work could lead to new silicon-based technologies in the above mentioned areas

What autocorrelation tells us about motor variability: Insights from dart throwing

In sports such as golf and darts it is important that one can produce ballistic movements of an object towards a goal location with as little variability as possible. A factor that influences this variability is the extent to which motor planning is updated from movement to movement based on observed errors. Previous work has shown that for reaching movements, our motor system uses the learning rate (the proportion of an error that is corrected for in the planning of the next movement) that is optimal for minimizing the endpoint variability. Here we examined whether the learning rate is hard-wired and therefore automatically optimal, or whether it is optimized through experience. We compared the performance of experienced dart players and beginners in a dart task. A hallmark of the optimal learning rate is that the lag-1 autocorrelation of movement endpoints is zero. We found that the lag-1 autocorrelation of experienced dart players was near zero, implying a near-optimal learning rate, whereas it was negative for beginners, suggesting a larger than optimal learning rate. We conclude that learning rates for trial-by-trial motor learning are optimized through experience. This study also highlights the usefulness of the lag-1 autocorrelation as an index of performance in studying motor-skill learning

Different populations and sources of human mesenchymal stem cells (MSC): A comparison of adult and neonatal tissue-derived MSC

The mesenchymal stroma harbors an important population of cells that possess stem cell-like characteristics including self renewal and differentiation capacities and can be derived from a variety of different sources. These multipotent mesenchymal stem cells (MSC) can be found in nearly all tissues and are mostly located in perivascular niches. MSC have migratory abilities and can secrete protective factors and act as a primary matrix for tissue regeneration during inflammation, tissue injuries and certain cancers

Гендерное сравнение непосредственных и среднесрочных результатов операции Озаки: анализ Propensity Score Matching

Highlights. A retrospective analysis of the patients’ data after Ozaki operation in four Russian Medical Centers was carried out. A comparative gender assessment of the immediate and medium-term results of Ozaki operation was performed.Aim. Gender assessment of Ozaki operation immediate and mid-term results in patients with aortic valve (AV) pathology.Methods. A retrospective multicenter study enrolled 251 patients (135 women, median age 66 (60–70) years old) who underwent Ozaki operation (2017–2020) was carried out in four centers in Russia. After propensity score matching, 92 patients were selected (mean age 65.8±10.8 years old). Two groups were formed in the gender structure: 46 females (average age 67.8±6.3 years old), 46 males (average age 63.8±15.4 years old). The main cause of AV dysfunction was severe aortic stenosis – in 86 (93.5%) cases. Chronic heart failure of III–IV functional class according to NYHA was observed in 26 (28.3%) patients. A bicuspid AV was in 24 cases (26.1%). The primary endpoint was hospital mortality. Postoperative complications and mid-term results (three-year overall survival and freedom from reoperation on AV) were assessed as secondary endpoints; the median follow-up period was 23 (18–33) months.Results. There was no statistically significant difference between the groups in the duration of surgery (275 minutes for females and 285 minutes for males, p = 0.4), cardiopulmonary bypass (98 minutes for females and 115 minutes for males, p = 0.3), aortic clamping (80 minutes for females and 93 minutes for males, p = 0.7). Hospital mortality among the studied patients did not differ: in the female group – 2.2% (1 case) and 0 in the male one, p = 0.9. There were no significant differences in postoperative complications: sepsis (2.2% in women and 0 in men, p = 0.9), superficial wound infection (8.7% in women and 6.5% in men, p = 0.9). Acute kidney injury, stroke, pacemaker implantation, resternotomy for bleeding were not observed in any patient. Three-year overall survival was 91.8% in females and 91.6% in males, p = 0.8; three-year freedom from reoperation – 94.4% for females and 100% for males, p = 0.1.Conclusion. Ozaki operation is equally reproducible with the same hospital mortality, postoperative complications, and medium-term outcomes in both females and males.Основные положения. Проведен ретроспективный анализ данных больных, перенесших операцию Озаки в четырех медицинских центрах России. • Выполнена сравнительная гендерная оценка непосредственных и среднесрочных результатов операции Озаки.Цель. Гендерная оценка непосредственных и среднесрочных результатов операции Озаки у пациентов с патологией аортального клапана (АК).Материалы и методы. Проведено ретроспективное многоцентровое исследование 251 больного (135 женщин, медиана возраста 66 (60–70) лет), которым выполнена операция Озаки (2017–2020 гг.) в четырех медицинских центрах России. После псевдорандомизации (propensity score matching) отобраны 92 пациента (средний возраст 65,8±10,8 года). В зависимости от гендерной принадлежности сформированы две группы: 46 женщин (средний возраст 67,8±6,3 года), 46 мужчин (средний возраст 63,8±15,4 года). Основной причиной дисфункции АК был тяжелый аортальный стеноз – 86 (93,5%) случаев. Хроническая сердечная недостаточность III–IV функционального класса по NYHA отмечена у 26 (28,3%) больных. В 24 случаях (26,1%) АК был двустворчатый. Первичной конечной точкой являлась госпитальная летальность. В качестве вторичных конечных точек оценивали послеоперационные осложнения и среднесрочные результаты (трехлетняя общая выживаемость и свобода от реоперации на АК), медиана периода наблюдения составила 23 (18–33) мес.Результаты. Не получено статистически значимой разницы между группами по длительности операции (275 мин у женщин и 285 мин у мужчин, p = 0,4), искусственного кровообращения (98 и 115 мин, p = 0,3), пережатия аорты (80 и 93 мин соответственно, p = 0,7). Госпитальная летальность среди исследуемых больных не различалась: в женской группе – 1 случай (2,2%), в мужской – 0, p = 0,9. По послеоперационным осложнениям значимых различий не зарегистрировано: сепсис (2,2% у женщин и 0 у мужчин, p = 0,9), раневая поверхностная инфекция (8,7 и 6,5% соответственно, p = 0,9). Острого повреждения почек, инсульта, имплантации постоянного электрокардиостимулятора, рестернотомии по поводу кровотечения не выявлено ни у одного пациента. Трехлетняя общая выживаемость составила 91,8% у женщин и 91,6% у мужчин, p = 0,8; трехлетняя свобода от реоперации – 94,4 и 100% соответственно, p = 0,1.Заключение Операция Озаки воспроизводима у мужчин и женщин с одинаковыми госпитальной летальностью, послеоперационными осложнениями и среднесрочными результатами.