Complete electromagnetic consideration of plasmon mode excitation in graphene rectangles by incident terahertz wave.

The excitation of terahertz plasmon modes in a graphene rectangle by normally incident linearly polarized electromagnetic wave has been theoretically studied. The complete electromagnetic approach based on formulation of the integral equations for sought-for electromagnetic quantities has been developed. The influence of edge-field effects on excitation of plasmon modes for different polarization of the incident wave and different shapes of graphene rectangle has been studied. The absorption cross-section spectra and the charge density distributions in graphene rectangle for different plasmon modes have been studied. It has been found that the edge-field effect, which results in spreading the plasmon field beyond the geometric boundaries of graphene rectangle, leads to considerable red shifts of the plasmon mode frequencies and modifies the plasmon mode dispersion.

Terahertz amplification and lasing by using transverse electric modes in a two-layer-graphene-dielectric waveguide structure with direct current.

We study for the first time the interaction between the waveguide modes of graphene structure and freely propagating terahertz (THz) electromagnetic waves (this interaction takes place within the light cone). We revealed a new and rather unexpected physical phenomenon by showing that freely incident THz electromagnetic waves can resonate with the surface transverse electric (TE) modes of the graphene waveguide in virtue of these modes having their dispersions in the vicinity of the light cone. The dispersion and amplification of surface TE modes in a dielectric waveguide covered with two graphene layers biased by direct current (DC), as well the amplification and lasing of incident THz wave by excitation of TE mode resonances, are investigated. The DC flows perpendicular to the direction of the surface wave propagation and creates the capacitive complex conductivity of graphene at THz frequencies, which is necessary for the existence of surface TE modes in graphene. The real part of graphene conductivity can be negative at THz frequencies due to DC in graphene which leads to amplification and lasing of THz radiation. Such structure can be of great practical importance because an external THz wave can be amplified or generated in lasing process without using special coupling elements commonly needed for ensuring the interaction between external THz wave and surface waveguide modes. The use of a two-layer graphene structure makes it possible to reduce the charge-carrier drift velocity required for reaching the lasing threshold at those resonances, as compared to a structure with a single graphene layer.

Terahertz transverse electric modes in graphene with DC current in hydrodynamic regime.

The dispersion, excitation, and amplification of electromagnetic transverse electric (TE) modes at terahertz (THz) frequencies in graphene in the hydrodynamic (HD) regime, with a direct electric current flowing perpendicular to the TE mode wavevector, were theoretically investigated. The expression for the nonlocal HD conductivity of graphene with a direct electric current flowing perpendicular to the TE mode wavevector was derived. The direct electric current in graphene leads to the capacitive nature of the graphene HD conductivity at THz frequencies, which makes TE modes exist in this frequency range. The excitation of TE modes in graphene by an incident THz wave was modeled for the attenuated total reflection geometry. A new physical mechanism of TE mode amplification in graphene effective for a low value of carrier drift velocity was predicted. THz lasing regimes with TE modes in graphene structure with direct electric current were found. The results of this work can be used to create miniature technologically feasible sources and amplifiers of THz radiation.

[Relationship between mental and physical disorders in old age and senility.]

In order to identify the relationship between mental and physical disorders in the elderly and senile age, 70 patients were examined in one of the clinics in Arkhangelsk, including 56 (80%) persons aged 60-74 years and 14 (20%) people aged 75 years and older. A questionnaire was conducted, data from outpatient records were studied, and the clinical status assessment was used, as well as methods for determining mental and physical condition. The most frequent mental and physical disorders were the cognitive and depressive disorders presence, a high risk of malnutrition syndrome, sarcopenia and falls syndrome, reduced functional capabilities, while senile patients had significantly more pronounced disorders. It has been shown that the cognitive and depressive disorders presence in the elderly and senile increases the falling syndrome risk and reduced functional capabilities, and in old age - sarcopenia syndrome.

[Outcomes of endoprosthetic repair of abdominal aortic aneurysm]. / Rezul'taty éndoprotezirovaniia anevrizmy briushnogo otdela aorty.

AIM: The study was aimed at assessing efficacy and safety of endovascular treatment of abdominal aortic aneurysms based on 11-year experience with implantation of stent grafts. PATIENTS AND METHODS: We retrospectively analysed outcomes of treatment of 242 patients with abdominal aortic aneurysm during the period from 2008 to 2019. Of these, 210 (86.78%) were males, mean age 69.32±7.36 years. Diagnosis was made using colour duplex scanning and contrast-enhanced multislice spiral computed tomography, with implanting the following stent grafts: Ella - 44, Ovation Prime - 33, Anaconda - 13, Endurand - 77, Aortix - 2, Zenith - 33, Seal - 39, with one endoprosthesis placement failed. Assessing safety of the operation, we took into consideration lethality due to aortic rupture/thrombosis. Efficacy was taken to mean technical success of the operation (implantation of all components of the endograft without switch to open surgery), the number of reoperations. RESULTS: Technical success of the operation was achieved in 98.35% of cases. In 1 case due to pronounced arterial calcification for technical reasons we failed to position the stent graft and in another case - the contralateral leg of the Ella prosthesis. The early postoperative period revealed: type A1 endoleak - 3.7%, type IB - 4.13%, type IIA - 6.6%, type IIB - 4.54%, type III - 0.83%, type IV - 0.83%. Repeat operations were performed in 20 (8.2%) patients within 30 days after the intervention and in 32 (13.22%) in the remote period. In the early postoperative period two conversions were performed: 1) iliorenal bypass grafting for restoration of blood flow through the renal artery occluded by endoprosthesis wall; 2) evacuation of retroperitoneal haematoma due to rupture of the common femoral artery. Lethality during the whole period of follow up amounted to 32 (13.22%) cases. Of these, due to aortic complications 4.54% (n=11) and due to accompanying pathology 8.67% (n=21). A direct correlation was revealed between the aortic diameter and duration of the operation which in turn increases the risk of complications requiring re-operation or resulting in a lethal outcome (RR - 1; 95% CD 1- 1; p=0.026). CONCLUSION: Our experience showed high safety and efficacy of stent graft implantation in treatment of patients with abdominal aortic aneurysms and high surgical risk.

Ultrafast Magneto-Optics in Nickel Magnetoplasmonic Crystals.

Here, we report on ultrafast all-optical modulation of the surface-plasmon (SP)-assisted transverse magneto-optical Kerr effect (TMOKE) and the reflectance in a one-dimensional nickel magnetoplasmonic crystal (MPC). A 50 fs nonresonant laser pump pulse with 7 mJ/cm2 fluence reduces the magnetization by 65%, which results in the suppression of TMOKE in the SP-resonant probe from 1.15% to 0.4%. The differential reflectance of SP-resonant probe achieves 5.5%. Besides this, it is shown that electron thermalization and relaxation in MPC are several times slower than those in the plane nickel.

[A study of the efficacy and safety of lornoxicam in patients with acute sciatica]. / Issledovanie effektivnosti i bezopasnosti vosproizvedennogo preparata lornoksikam u patsientov s ostroi lyumboishialgiei.

OBJECTIVE: To compare the efficacy, safety and tolerability of lornoxicam and xefocam used as the reference drug in patients with acute nonspecific pain in lower back caused by acute sciatica. MATERIAL AND METHODS: A simple blind clinical study was conducted with 108 patients (men and women, aged 20-55 years) with complaints of pain in the lower back and an established diagnosis of vertebrogenic radiculopathy L4, L5, S1. Patients were randomized into 2 treatment groups by randomization method of envelopes in the ratio of 1:1 (54 patients per group). The first group received lornoxicam in a dose of 16 mg/day for 2 days, the second group was treated with xefocam (the lyophilisate for preparation of solution for intravenous and intramuscular injection) according to a similar scheme. RESULTS AND CONCLUSION: The results demonstrate the comparable efficacy of lornoxicam and the reference drug. The analysis of the safety profile reveals no significant differences between treatment groups.

[The modern characteristics of quality of ambulatory polyclinic medical care of patients of elderly age].

The organization of out-patient care of elderly people has its own clinical and organizational characteristics. The study was carried out to establish quality factors of ambulatory polyclinic medical care of elderly people from the position of attending physician. The sampling consisted of 80 physicians interviewed. Out of them 70 were females (87.5%), 50 local therapists and general practitioners and 30 physicians of various specialties. The genuinely elaborated questionnaire was applied. Results and discussion. It is established that most physicians are aware of the need of improving quality of medical care of elderly patients and developing geriatric care. The percentage of elderly patients in ambulatory polyclinic network makes up to 50%, and in particular cases up to 60-70%. The majority of elderly patients visit their physician 1-2 times per month. More than 50% of physicians consider elderly patients have to be observed by physicians of geriatric profile that confirms actual need in this medical specialty. The social and organizational factors of quality of medical care are identified: insufficient duration of physician admission, low level of preferential medications support, lacking of cash resources in patients to purchase prescribed medications, difficulties in making an appointment to medical specialist and district physician, difficult access of medical organization. The orientation of doctors in provision of care to elderly patients only to medication therapy is established. Conclusion. The specific characteristics of identified factors of quality of medical care of elderly patients are to be considered in developing directions of optimizing medical care for this contingent.

Position of an acoustic window in a beluga whale: Computation based on auditory evoked potential latencies.

In a beluga whale, the positions of sound receiving areas on the head surface were determined by comparing the acoustic delays from different sound source positions. For this investigation, auditory evoked potentials (AEPs) in response to short tone pips were recorded. Latencies of the first AEP wave that presumably reflected the activity of the auditory nerve were measured at different sound source azimuths. For AEPs of equal amplitudes, the difference in AEP latencies was attributed to the difference in the acoustic delays. These delay differences were used to compute the azimuths of sound receiving points. Measurements were conducted at frequencies from 22.5 to 90 kHz in half-octave steps. At all stimulus frequencies, the receiving points were located 24-38 cm caudal of the melon tip, which is near a proximal part of the lower jaw. Thus, the results indicated the latero-mandibular acoustic window. Possible causes for not finding a lateral or ventro-mandibular window are discussed.

Nanofocusing and deceleration of terahertz plasma waves in tapered metal-insulator-graphene heterostructure.

Nanofocusing and deceleration of terahertz plasma waves in tapered metal-insulator-graphene heterostructure is studied theoretically. It is shown that, choosing an appropriate value of taper length for given values of the taper angle and the Fermi energy in a doped or gated graphene, the plasma wave energy density value in the vicinity of the taper apex exceeds its value in the taper inlet cross-section by tens of percent in spite of the Drude losses in graphene. The plasma wave decelerates while moving toward taper apex and its energy velocity becomes several times smaller as compared to that in the taper inlet cross-section.

Influence of the Background Noise on Recognition of Signals with a Complex Spectrum Structure in the Beluga Whale (Delphinapterus leucas).

The frequency resolving power of hearing (FRP) of the beluga whale Delphinapterus leucas was studied as dependent on influence of lasting low-intensity sounds (of the ultrasonic range from -20 to +10 dB). Testing of the spectrum ripple-phase reversal was used in conjunction with a noninvasive recording of auditory evoked potentials. FRP parameters were found to depend nonmonotonically on the intensity of the background noise. The resultant adaptation effects can be explained by the fact that, in response to the high-intensity signals, the auditory system sensitivity is reduced to the level optimal for analysis of these signals.

Sharpening of the Signal Spectrum Contrast as a Result of Lateral Suppression in the Human Auditory System.

The spectrum contrast threshold for the comb-filtered signal was measured at various ripple densities in listeners with normal hearing. The lowest spectrum contrast thresholds of less than 0.1 appeared at a ripple density of 3-4 oct-1. With the ripple density falling down to 1 oct-1, the threshold increased to 0.17. At the ripple density higher than 4 oct-1, the threshold was also growing to achieve 1.0 at a density of 7-8 oct-1. An increase of threshold at high ripple densities can be explained by integration within critical bands. At low ripple densities, the threshold increase may be a result of the lateral suppression that led to sharpening of the spectral contrast.

Giant amplification of terahertz plasmons in a double-layer graphene.

The amplification of terahertz plasmons in a pair of parallel active graphene monolayers is studied theoretically. The plasmon wave in a symmetric double-layer graphene structure splits into two branches with a symmetric and an antisymmetric distribution of tangential to graphene component of the electric field across the plane of symmetry of the structure. It is shown that, normalized to the wavelength, the terahertz plasmon amplification factor of the symmetric mode in the double-layer graphene structure could be greater than that in a single graphene layer by four orders of magnitude.

[Cognitive and affective disorders in the elderly].

To develop algorithm of diagnostics of cognitive and affective disorders in elderly and senile age 98 representatives of this age group were examined (1st group - 68 persons 60-74 years, 2nd group - 30 patients older than 75 years). For the diagnosis of cognitive disorders the developed and adapted «Short rating scale of cognitive functions¼, to diagnose emotional disorders - «Ðospital scale of anxiety and depression HADS¼ were used. Cognitive impairment was revealed in 39,8% of the elderly (1st group - 28,7% in 2nd group - 61,6%). Affective disorders 51,6% of respondents had; however, signs of anxiety - 40,9% and depression - 27,7%. Algorithm for the diagnosis of cognitive and emotional disorders in elderly and senile age, comprising the steps of: screening and diagnostic, clinical and pathopsychological, laboratory and instrumental diagnostic, psychodiagnostic, can be recommended for use in general medical practice (therapists, general practitioners, geriatrics) for an earlier secondary prevention and, if necessary, early correction of mental health disorders.

[DIAGNOSIS OF EMOTIONAL SPHERE DISORDERS IN ELDERLY].

The article describes the structure of criteria of severity and recommendations for the diagnosis of emotional sphere disorders in elderly. An algorithm for diagnosis of emotional sphere is described, which includes four phases: screening and diagnostic, clinical and patho-psychological, laboratory and instrumental diagnostic, psycho-diagnostic; it can be applied as to estimate the prevalence of various forms of emotional disorders, and for their early correction and prevention at the individual level. The criteria of anxiety expression evaluation and asthenic disorders are presented. The recommendations can be used in the activities of somatic practices doctors (therapist, general practitioners, neurologists).

[INFECTIOUS ENDOCARDITIS IN PREGNANT WOMEN].

A case of primary infectious endocarditis with the lesion of mitral valve in a pregnant woman is reported The diseases was caused by meticillin-resistant Staphylococcus aureus. Special attention is given to inefficiency of beta-lactame antibiotics against this infection and beneficial effect of daptomycin therapy. This observation confirms literature data about high frequency of thromboembolic complications of S aureus-induced infectious endocarditis due to the production of various coagulases and von Willebrand factor-binding protein by these microorganisms. An increase of coagulation caused by S. aureus is mediated through activation of prothrombin, factor XIII, and fibrin-binding fibronectin. It requires prescription of direct thrombin inhibitor pradax that proved to yield good results in the treatment of our patient. It is concluded that infectious endocarditis in pregnant women is characterized by an atypical clinical picture due to impaired immunity associated with rapid progression of the process after delivery, high frequency of thromboembolic and DIC syndromes.

[cardiovascular system and cognitive disorders in male drivers].

The authors found statistically significant differences in cognitive tests results between group of drivers and reference group (p = 0,021). Correlation analysis proves statistically reliable relationship between cognitive functions and hemodynamic as well as morphologic parameters of cardiovascular system.

[A clinical efficacy of electrode pharmaphoresis in treatment of railway workers with low-back pain].

OBJECTIVE: To evaluate clinical efficacy and tolerability of electrode pharmaphoresis using preparations xefocam and mydocalm-richter in railway workers with low-back pain. MATERIAL AND METHODS: Authors carried out an open prospective noncomparative study of 16 patients, aged 21-82 years, with spinal osteochondrosis with root syndrome and radiculopathia of the lumbar/sacral spine with pain syndrome regardless of its duration. Treatment efficacy was assessed by the dynamics of pain syndrome severity based on the scores of a self-rated scale completed by the patient and the McGill Pain Questionnaire. Quality-of-life was assessed with the Oswestry Disability Index before and in the end of treatment. Clinical outcome was evaluated with the modified Nurick scale. Electrode pharmaphoresis (the "Farma T.E.B. Trans Epidermal Barrier Physio" apparatus) was administered to all patients using xefocam (solution for injections 8 mg, 2 ml per procedure) and mydocalm-richter (solution for injections 100 mg, 2 ml per injection) in the lumbar/sacral spine. RESULTS AND CONCLUSION: The high clinical efficacy of electrode pharmaphoresis using xefocam and mydocalm-richter was shown. The complex restoration study resulted in the reduction of pain syndrome in all patients. Pain severity was reduced to mild grade in 68.8% to the middle of treatment and in 93.8% patients in the end of treatment. As a consequence of pain reduction, the functional activity (quality of self-service, daily activities) increased significantly in 68.8% of patients. Positive treatment effect was noted in 100% of patients, good tolerability of this medication in 87.5%.

[Performance of fragmenting operation for restoration of a correct rhythm while treating the isolated failure of a mitral valve].

Possibilities of application of the proposed procedure for intraoperative restoration of the sinus rhythm while the mitral valve prosthesis (MVP) were studied up. In 161 patients, suffering the isolated mitral valve failure stage IV, a surgical treatment was conducted in Department of surgical treatment of acquired heart failures. The left atrium plasty was conducted in 119 (73.9%) of them with the objective to reduce its size and eliminate the re-entry waves passability. Fragmentation in left atrium was conducted in lowradiofrequency regime of diathermy (25-35 W) in accordance to variant (cut and sew) of operations Maze - 3 and Maze - 4. On a hospital stage 3 patients died (hospital lethality 1.9%). MVP in combination with Maze operation in a lowradiofrequency regime have permitted to restore successfully a correct rhythm in 80.2% of patients on a hospital stage and to stabilize it during 1 year postoperatively.

[Plasty of the left atrium in the isolated mitral valve prosthesis implantation].

Possibilities of the procedures conduction of the left atrium (LA) plasty in a mitral valve prosthesis (MVP) were studied. There were examined 553 patients, in whom surgical treatment in the clinic was conducted. In all the patients MVP was conducted for isolated mitral valve failure and dilatation of LA. In 371 patients (the main group) MVP and LA plasty were conducted, in 182 (control group)--LA was not corrected. Morphometric indices of left cardiac cameras, survival, stability of the operation good results in late terms have witnessed high efficiency of MVP with LA reduction in comparison with such in a control group. Late results of MVP in conjunction with LA reduction exceed such in a control group, witnessing expediency of the proposed methods of surgical treatment application.