Precision Quantum Hall Resistance Measurement on Epitaxial Graphene Device in Low Magnetic Field

Precision quantum Hall resistance (QHR) measurements were performed on large-area epitaxial graphene device at low magnetic fields (B = 2 T - 8 T) at temperature T = 1.5 K. Hall resistance was measured using Cryogenic Current Comparator resistance bridge with high biasing current Isd = 40 micro ampere. The results showed that at B = 8 T the relative deviation of Hall resistance from the expected quantized value h/2e2 is within experimental uncertainty of 3.5 parts in 108 and remained below 0.35 parts per million (ppm) down to B = 3 T

Role of Toll-like receptors in development of postpartum endometritis

The aim of the study was to establish the association between expression of TLR1 (ligands - triacyl lipopeptides), TLR2 (ligands - lipopeptides, lipoteichoic acid, zymosan), and TLR 5 (ligand - flagellin) of cervical epithelial cells in vivo and development of postpartum endometritis in women with high infection riskyesBelgorod State Universit

Structure and operational properties of porous cermets on the basis of alloyed steel scale

Compositions of batches for obtaining porous cermets on the basis of alloyed steel scale with addition of ferrosilicon have been developed. Roentgenograms of the obtained alloys were shown, mechanical durability and porosity of the obtained materials were investigated. The model of formation of porous cermets was offere

Psycho-pedagogical support of professional self as a social worker in the period of study in further education

The article deals with issues of professional improvement of social workers, the role of psychological and pedagogical support their professional and personal development during the period of study in the system of additional professional education, forms, methods, technologies of the educational process, contributing to this development.В статье рассматриваются вопросы профессионального самосовершенствования социальных работников, роль психолого-педагогического сопровождения их профессионально-личностного развития в период обучения в системе дополнительного профессионального образования, формы, методы, технологии учебно-образовательного процесса, способствующие данному развитию

Towards a Graphene-Based Quantum Impedance Standard

Precision measurements of the quantum Hall resistance with alternating current (ac) in the kHz range were performed on epitaxial graphene in order to assess its suitability as a quantum standard of impedance. The quantum Hall plateaus measured with alternating current were found to be flat within one part in 10^7. This is much better than for plain GaAs quantum Hall devices and shows that the magnetic-flux-dependent capacitive ac losses of the graphene device are less critical. The observed frequency dependence of about -8x10^-8/kHz is comparable in absolute value to the positive frequency dependence of plain GaAs devices, but the negative sign is attributed to stray capacitances which we believe can be minimized by a careful design of the graphene device. Further improvements thus may lead to a simpler and more user-friendly quantum standard for both resistance and impedance

Spin disorder scattering in a ferromagnetic insulator-on-graphene structure

We theoretically study the transport properties of a single graphene layer between two insulating materials, i.e., a ferromagnetic EuO thin film and a nonmagnetic SiC substrate. An exchange interaction between the charge carrier spins in graphene and the localized magnetic moments in the ferromagnetic insulator is assumed. This proximity effect and the large spin fluctuations at temperatures close to the ferromagnetic transition temperature TC lead to spin disorder scattering, which is calculated using a Green's function technique. Numerical results indicate that at temperatures close to TC the contribution of the spin disorder scattering to the total electron mobility is clearly observable even in the case of a weak exchange interaction and a low background mobility of the graphene layer. This enables the experimental determination of the exchange interaction parameter using the present model and a simple resistivity measurement.Peer reviewe

Optimizing outpatient total hip arthroplasty: perspectives of key stakeholders

Background Advances in surgical techniques combined with multimodal analgesia and early rehabilitation have potentiated early mobilization in patients undergoing total hip arthroplasty (THA). Given an increasing push from patients to accelerate recovery and health care budgetary limitations, there has been growing interest in the implementation of outpatient THA in selected patients. Understanding the patient and primary caregiver experience of outpatient THA is important to optimize care. We aimed to gain insight into patient and caregiver perspectives regarding the perceived advantages and disadvantages of same-day discharge to identify areas of care that can be improved. Method Using a qualitative descriptive approach, we conducted in-depth semistructured interviews with patient-primary caregiver dyads who experienced same-day discharge or standard care after primary THA with the direct anterior approach in 2016-2017. Two members of the research team coded the data independently, implementing a thematic and content analysis. Results Twenty-eight participants (16 same-day discharge, 12 standard care) were included. Both groups experienced high levels of satisfaction with their care pathway. Concerns and challenges identified in both groups pertained to mobility, pain, self-care and caregiver support. Challenges and concerns unique to same-day discharge were identified regarding expectations for recovery, medications and their impact on mobility, the timing of postoperative education and the availability of formal care. Conclusion Outpatient THA can be implemented with high patient and caregiver satisfaction. Preoperative education, clarification of recovery processes and expectations, and proactively addressing concerns related to caregiving are important

Some features of the bioelectric activity of the muscles with prolonged hypokinesia

The effects of prolonged hypokinesia, brought on by confinement to bed and the attendant lack of motor activity, on the bioelectric activity of muscles are studied. Electromyographic measurements of amplitude and frequency indicators of muscular bioelectric activity were analyzed

Sentinel headache as a warning symptom of ischemic stroke

Background: There are no previous controlled studies of sentinel headache in ischemic stroke. The purpose of the present study was to evaluate the presence of such headache, its characteristics and possible risk factors as compared to a simultaneous control group. Methods: Eligible patients (n = 550) had first-ever acute ischemic stroke with presence of new infarction on magnetic resonance imaging with diffusion-weighted imaging (n = 469) or on computed tomography (n = 81). As a control group we studied in parallel patients (n = 192) who were admitted to the emergency room without acute neurological deficits or serious neurological or somatic disorders. Consecutive patients with stroke and a simultaneous control group were extensively interviewed soon after admission using validated neurologist conducted semi-structured interview forms. Based on our previous study of sentinel headache in transient ischemic attacks we defined sentinel headache as a new type of headache or a previous kind of headache with altered characteristics (severe intensity, increased frequency, absence of effect of drugs) within seven days before stroke. Results: Among 550 patients with stroke 94 patients (17.1%) had headache during seven days before stroke and 12 (6.2%) controls (p < 0.001; OR 3.9; 95% CI 1.7-5.8). Totally 81 patients (14.7%) had sentinel headache within the last week before stroke and one control. Attacks of arrythmia during seven days before stroke were significantly associated with sentinel headache (p = 0.04, OR 2.3; 95% CI 1.1-4.8). Conclusions: A new type of headache and a previous kind of headache with altered characteristics during one week before stroke are significantly more prevalent than in controls. These headaches represent sentinel headaches. Sudden onset of such headaches should alarm about stroke. © 2020 The Author(s)