We determined electronic relaxation times via pump-probe optical spectroscopy using sub-15 fs pulses for the normal state of two different cuprate superconductors. We show that the primary relaxation ...process is the electron-phonon interaction and extract a measure of its strength, the second moment of the Eliashberg function λω2 = 800 ± 200 meV2 for La(1.85)Sr(0.15)CuO4 and λω2 = 400 ± 100 meV2 for YBa(2)Cu(3)O(6.5). These values suggest a possible fundamental role of the electron-phonon interaction in the superconducting pairing mechanism.
Memory traces for words are frequently conceptualized neurobiologically as networks of neurons interconnected via reciprocal links developed through associative learning in the process of language ...acquisition. Neurophysiological reflection of activation of such memory traces has been reported using the mismatch negativity brain potential (MMN), which demonstrates an enhanced response to meaningful words over meaningless items. This enhancement is believed to be generated by the activation of strongly intraconnected long-term memory circuits for words that can be automatically triggered by spoken linguistic input and that are absent for unfamiliar phonological stimuli. This conceptual framework critically predicts different amounts of activation depending on the strength of the word's lexical representation in the brain. The frequent use of words should lead to more strongly connected representations, whereas less frequent items would be associated with more weakly linked circuits. A word with higher frequency of occurrence in the subject's language should therefore lead to a more pronounced lexical MMN response than its low-frequency counterpart. We tested this prediction by comparing the event-related potentials elicited by low- and high-frequency words in a passive oddball paradigm; physical stimulus contrasts were kept identical. We found that, consistent with our prediction, presenting the high-frequency stimulus led to a significantly more pronounced MMN response relative to the low-frequency one, a finding that is highly similar to previously reported MMN enhancement to words over meaningless pseudowords. Furthermore, activation elicited by the higher-frequency word peaked earlier relative to low-frequency one, suggesting more rapid access to frequently used lexical entries. These results lend further support to the above view on word memory traces as strongly connected assemblies of neurons. The speed and magnitude of their activation appears to be linked to the strength of internal connections in a memory circuit, which is in turn determined by the everyday use of language elements.
Abstract
The existing system of training specialists in the field of applied physics in domestic universities doesn’t allow to fully meet the needs of employers. One of the main drawbacks of the ...educational process in higher education institution in training future engineers is insufficient use of practice-oriented educational technologies, well-organized internships and independent work of students, real design. It does not give students an opportunity to demonstrate the competences they have acquired while studying individual disciplines of the educational program. According to experts, one of the ways to improve the quality of specialists’ training, capable of eliminating this contradiction to a certain extent, is the introduction and wider spread of practice-oriented educational technologies in engineering universities. The objective of the applied physics course is to develop skills in applying the provisions of fundamental physics to competent scientific analysis of situations which an engineer has to deal with when creating new equipment and new technologies, as well as to develop students’ natural-science worldview and familiarize them with the history of physics development and its main discoveries. As a result of mastering the course of applied physics the student should learn the basic physical phenomena and basic laws of physics; limits of their applicability, application of laws in the most important practical applications; become familiar with the basic physical quantities, know their definition, meaning, methods and units of their measurement; imagine fundamental physical experiments and their role in the development of science; know the purpose and operating principles of the most important physical instruments.
We report a new synthetic aperture optical microscopy in which high-resolution, wide-field amplitude and phase images are synthesized from a set of Fourier holograms. Each hologram records a region ...of the complex two-dimensional spatial frequency spectrum of an object, determined by the illumination field's spatial and spectral properties and the collection angle and solid angle. We demonstrate synthetic microscopic imaging in which spatial frequencies that are well outside the modulation transfer function of the collection optical system are recorded while maintaining the long working distance and wide field of view.
Transcranial Doppler is a useful ancillary test for brain death confirmation because it is safe, noninvasive, and done at the bedside. Transcranial Doppler confirms brain death by evaluating cerebral ...circulatory arrest. Case series studies have generally reported good correlations between transcranial Doppler confirmation of cerebral circulatory arrest and clinical confirmation of brain death. The purpose of this study is to evaluate the utility of transcranial Doppler as an ancillary test in brain death confirmation.
We conducted a systematic review of the literature and a diagnostic test accuracy meta-analysis to compare the sensitivity and specificity of transcranial Doppler confirmation of cerebral circulatory arrest, by using clinical confirmation of brain death as the criterion standard.
We identified 22 eligible studies (1671 patients total), dating from 1987 to 2014. Pooled sensitivity and specificity estimates from 12 study protocols that reported data for the calculation of both values were 0.90 (95% CI, 0.87-0.92) and 0.98 (95% CI, 0.96-0.99), respectively. Between-study differences in the diagnostic performance of transcranial Doppler were found for both sensitivity (I(2) = 76%; P < .001) and specificity (I(2) = 74.3%; P < .001). The threshold effect was not significant (Spearman r = -0.173; P = .612). The area under the curve with the corresponding standard error (SE) was 0.964 ± 0.018, while index Q test ± SE was estimated at 0.910 ± 0.028.
The results of this meta-analysis suggest that transcranial Doppler is a highly accurate ancillary test for brain death confirmation. However, transcranial Doppler evaluates cerebral circulatory arrest rather than brain stem function, and this limitation needs to be taken into account when interpreting the results of this meta-analysis.
Optical Fluoride Nanoceramics Kuznetsov, S. V.; Alexandrov, A. A.; Fedorov, P. P.
Inorganic materials,
06/2021, Letnik:
57, Številka:
6
Journal Article
Recenzirano
—
This paper examines methods for the fabrication of optical fluoride nanoceramics and the compaction behavior of precursor powders. We discuss the basic drawbacks to the ceramics under consideration ...from the viewpoint of the physicochemical properties of fluorides. Lasing in ceramics has been demonstrated in the visible (praseodymium) and IR (neodymium, erbium, thulium, and ytterbium) spectral regions. The advantages of optical ceramics include the possibility of preparing large-aperture samples with improved mechanical characteristics and the presence of their own set of defects, including extensive polysynthetic twinning, which leads to the formation of new optical centers.
During the steel pipeline installation, special attention is paid to the butt weld control performed by fusion welding. The operation of the currently popular automated X-ray and ultrasonic testing ...complexes is associated with high resource and monetary costs. In this regard, this work is devoted to the development of alternative and cost-effective means of preliminary quality control of the work performed based on the visual testing method. To achieve this goal, a hardware platform based on a single board Raspberry Pi4 minicomputer and a set of available modules and expansion cards is proposed, and software whose main functionality is implemented based on the systemic application of computer vision algorithms and machine learning methods. The YOLOv5 object detection algorithm and the random forest machine learning model were used as a defect detection and classification system. The mean average precision (mAP) of the trained YOLOv5 algorithm based on extracted weld contours is 86.9%. A copy of YOLOv5 trained on the images of control objects showed a mAP result of 96.8%. Random forest identifying of the defect precursor based on the point clouds of the weld surface achieved a mAP of 87.5%.
Background and purpose
Intracranial hemorrhage (ICH) is the most feared complication in patients treated with oral anticoagulants due to non‐valvular atrial fibrillation. Non‐vitamin K oral ...anticoagulants (NOACs) reduce the risk of ICH compared with vitamin K antagonists (VKAs). We performed a systematic review and meta‐analysis to evaluate the risk of fatal NOAC‐related ICH compared with VKA‐related ICH.
Methods
We calculated the corresponding risk ratios (RRs) in each included study to express the relative risk of fatal ICH amongst all patients receiving oral anticoagulation with either NOACs or VKAs. We additionally evaluated the mortality rates in NOAC‐related ICH in patients treated with and without NOAC‐specific reversal agents (idarucizumab and factor Xa inhibitors antidote). Case fatality was evaluated at 30–90 days following symptom onset.
Results
Our literature search identified six eligible studies (four randomized controlled trials and two open‐label trials of NOAC‐specific reversal agents). In pairwise analyses, NOACs were found to have a lower risk of fatal ICH compared with VKAs RR, 0.46; 95% confidence interval (CI), 0.36–0.58 with no heterogeneity (I2 = 0%) across included randomized controlled trials. However, the case fatality rate was similar in NOAC‐related and VKA‐related (RR, 1.00; 95% CI, 0.84–1.19) ICH with no evidence of heterogeneity (I2 = 0%). In the indirect analysis, the case fatality rate of NOAC‐related ICH in patients treated with specific reversal agents was lower compared with the remainder of the patients 17% (95% CI, 11–24%) vs. 41% (95% CI, 34–49%); P < 0.001.
Conclusions
Non‐vitamin K oral anticoagulants halve the risk of fatal ICH in patients with non‐valvular atrial fibrillation compared with VKAs, whereas indirect comparisons indicate that NOAC‐specific reversal agents may be associated with a lower case fatality rate in NOAC‐related ICH.
The paper examines the possibility to create a three-dimensional model of cadastral objects – cadastral parcels and buildings, exploring different spatial data acquisition technologies. Four ...cadastral parcel and part of the buildings situated in them are selected for the range of the task. Self-contained objects located in buildings have not been examined. The objects are located on the territory of Lozenets District, Sofia, which is highly urbanized part of the capital. In order to create a three-dimensional model, classical land surveying measurements with a total station and mobile laser scanning were performed.In addition, the acquired data is assessed. It is made by comparing measurements of the building to the measurements of the registered point cloud. The assessment results show that the mobile laser scanning technology is efficient to reproduce high quality and accurate data for existing building structures due to MLS advantages – the large range, high accuracy, fast data acquisition and high level of detail.The paper is a part of Alexander Alexandrov master thesis.
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