Electrostatic effects in coupled quantum dot-point contact-single electron transistor devices

We study the operation of a system where quantum dot (QD) and point contact (PC) defined in a two-dimensional electron gas of a high-mobility GaAs/AlGaAs heterostructure are capacitively coupled to each other and to metallic single electron transistor (SET). The charge state of the quantum dot can be probed by the point contact or single electron transistor. These can be used for sensitive detection of terahertz radiation. In this work, we explore an electrostatic model of the system. From the model, we determine the sensitivity of the point contact and the single electron transistor to the charge excitation of the quantum dot. Nearly periodic oscillations of the point contact conductance are observed in the vicinity of pinch-off voltage. They can be attributed to Coulomb blockade effect in a quasi-1D channel because of unintentional formation of small quantum dot. The latter can be a result of fluctuations in GaAs quantum well thickness

UBVRI observations of the flickering of RS Ophiuchi at Quiescence

We report observations of the flickering variability of the recurrent nova RS Oph at quiescence on the basis of simultaneous observations in 5 bands (UBVRI). RS Oph has flickering source with (U-B)_0=-0.62 \pm 0.07, (B-V)_0=0.15 \pm 0.10, (V-R)_0=0.25 \pm 0.05. We find for the flickering source a temperature T_fl = 9500 \pm 500 K, and luminosity L_fl = 50 - 150 L_sun (using a distance of d=1.6kpc). We also find that on a (U-B) vs (B-V) diagram the flickering of the symbiotic stars differs from that of the cataclysmic variables. The possible source of the flickering is discussed. The data are available upon request from the authors and on the web www.astro.bas.bg/~rz/RSOph.UBVRI.2010.MNRAS.tar.gz.Comment: 7 pages, MNRAS (accepted

Structure and Magnetism of Neutral and Anionic Palladium Clusters

The properties of neutral and anionic Pd_N clusters were investigated with spin-density-functional calculations. The ground state structures are three-dimensional for N>3 and they are magnetic with a spin-triplet for 2<=N<=7 and a spin nonet for N=13 neutral clusters. Structural- and spin-isomers were determined and an anomalous increase of the magnetic moment with temperature is predicted for a Pd_7 ensemble. Vertical electron detachment and ionization energies were calculated and the former agree well with measured values for anionic Pd_N clusters.Comment: 5 pages, 3 figures, fig. 2 in color, accepted to Phys. Rev. Lett. (2001

The role of P2 receptor-mediated component in neurogenic tone control of human great saphenous vein

© 2017, Nizhny Novgorod State Medical Academy. All rights reserved.The aim of the investigation was to evaluate experimentally the role of the P2 receptor-mediated component in neurogenic tone control of human varicose-affected and healthy great saphenous vein (GSV). Materials and Methods. The material for the study were segments of GSV obtained from two groups of patients: group 1 (n=14) included patients with varicose vein disease, in whom GSV was removed during surgical treatment; group 2 (n=21) comprised patients with coronary artery disease who underwent coronary artery bypass grafting using GSV as an autograft. Mechanical activity of the isolated veins was studied in vitro by electrical stimulation before and after incubation with atropine and phentolamine, pyridoxal-phosphate-6-azophenyl- 2’,4’-disulfonate (PPADS) and suramin (both nonselective antagonists of P2 receptors), and also after desensitization of P2X receptors by a,ß-methylene ATP. Results. Atropine and phentolamine did not completely inhibit the contractile responses evoked by electric field stimulation of the varicose and non-varicose GSV. PPADS (10 and 30 µM) and suramin (100 and 300 µM) significantly reduced the contractile amplitude of GSV response in both groups of veins (p0.05). Atropine, phentolamine and PPADS inhibited the contractile responses to a lesser extent in the varicose-affected veins compared to the veins unaffected by varicose disease. Conclusion. These experimental results suggest the presence of the P2 receptor-mediated component in the neurogenic control of human GSV tone. Further studies of the P2 receptor mechanism of action is promising for the development of drugs both for treating varicose veins and for preventing spasm of the venous grafts after aortocoronary bypass surgery

Azoloazines as Perspective Antiglycating Agents for Therapy of Diabetes Complications

This work was supported by Russian Federation Ministry of education and science (grant № 4.6351.2017/8.9) and Russian Foundation for Basic Research (grant № 18-03-00787)

GAN-based multiple adjacent brain MRI slice reconstruction for unsupervised alzheimer’s disease diagnosis

Unsupervised learning can discover various unseen diseases, relying on large-scale unannotated medical images of healthy subjects. Towards this, unsupervised methods reconstruct a single medical image to detect outliers either in the learned feature space or from high reconstruction loss. However, without considering continuity between multiple adjacent slices, they cannot directly discriminate diseases composed of the accumulation of subtle anatomical anomalies, such as Alzheimer's Disease (AD). Moreover, no study has shown how unsupervised anomaly detection is associated with disease stages. Therefore, we propose a two-step method using Generative Adversarial Network-based multiple adjacent brain MRI slice reconstruction to detect AD at various stages: (Reconstruction) Wasserstein loss with Gradient Penalty + L1 loss---trained on 3 healthy slices to reconstruct the next 3 ones---reconstructs unseen healthy/AD cases; (Diagnosis) Average/Maximum loss (e.g., L2 loss) per scan discriminates them, comparing the reconstructed/ground truth images. The results show that we can reliably detect AD at a very early stage with Area Under the Curve (AUC) 0.780 while also detecting AD at a late stage much more accurately with AUC 0.917; since our method is fully unsupervised, it should also discover and alert any anomalies including rare disease.Comment: 10 pages, 4 figures, Accepted to Lecture Notes in Bioinformatics (LNBI) as a volume in the Springer serie

Application of deep learning in detecting neurological disorders from magnetic resonance images: a survey on the detection of Alzheimer’s disease, Parkinson's disease and schizophrenia

Neuroimaging, in particular magnetic resonance imaging (MRI), has been playing an important role in understanding brain functionalities and its disorders during the last couple of decades. These cutting-edge MRI scans, supported by high-performance computational tools and novel ML techniques, have opened up possibilities to unprecedentedly identify neurological disorders. However, similarities in disease phenotypes make it very difficult to detect such disorders accurately from the acquired neuroimaging data. This article critically examines and compares performances of the existing deep learning (DL)-based methods to detect neurological disorders—focusing on Alzheimer’s disease, Parkinson’s disease and schizophrenia—from MRI data acquired using different modalities including functional and structural MRI. The comparative performance analysis of various DL architectures across different disorders and imaging modalities suggests that the Convolutional Neural Network outperforms other methods in detecting neurological disorders. Towards the end, a number of current research challenges are indicated and some possible future research directions are provided

New antiglycating agents for diabetes therapy

It was shown that azoloazines (1) demonstrated higher antiglycation activity than reference compound, aminoguanidine, and have some potential as dipeptidylpeptidase-4 inhibitors. By given results this class of heterocycles can be considered as candidate for extended studies to develop drugs against complications of T2DM [1-4].The work was supported by the Ministry of Education and Science of Russia (grant №0836-2020-0058)