Pressure Instability Research Articles

AstroSat View of Spectral Transition in the Changing-look Active Galaxy NGC 1566 during the Declining Phase of the 2018 Outburst

Abstract NGC 1566 is a changing-look active galaxy that exhibited an outburst during 2017–2018 with a peak in 2018 June. We triggered AstroSat observations of NGC 1566 twice in 2018 August and October during its declining phase. Using the AstroSat observations, along with two XMM-Newton observations in 2015 (pre-outburst) and 2018 June (peak outburst), we found that the X-ray power law, the soft X-ray excess, and the disk components showed extreme variability during the outburst. Especially, the soft excess was negligible in 2015 before the outburst, increased to a maximum level by a factor of >200 in 2018 June, and reduced dramatically by a factor of ∼7.4 in 2018 August and became undetectable in 2018 October. The Eddington fraction (L/L Edd) increased from ∼0.1% (2015) to ∼5% (2018 June) and then decreased to ∼1.5% (2018 August) and 0.3% (2018 October). Thus, NGC 1566 made a spectral transition from a high soft-excess state to a negligible soft-excess state at a few percent of the Eddington rate. The soft excess is consistent with warm Comptonization in the inner disk that appears to have developed during the outburst and disappeared toward the end of the outburst over a timescale comparable to the sound-crossing time. The multiwavelength spectral evolution of NGC 1566 during the outburst is most likely caused by the radiation pressure instability in the inner regions of the accretion disk in NGC 1566.

Triggered and controlled release of active gaseous/volatile compounds for active packaging applications of agri-food products: A review.

Gaseous and volatile active compounds are versatile to enhance safety and preserve quality of agri-food products during storage and distribution. However, the use of these compounds is limited by their high vapor pressure and/or chemical instability, especially in active packaging (AP) applications. Various approaches for stabilizing and controlling the release of active gaseous/volatile compounds have been developed, including encapsulation (e.g., into supramolecular matrices, polymer-based films, electrospun nonwovens) and triggered release systems involving precursor technology, thereby allowing their safe and effective use in AP applications. In this review, encapsulation technologies of gases (e.g., CO2 , ClO2 , SO2 , ethylene, 1-methylcyclopropene) and volatiles (e.g., ethanol, ethyl formate, essential oils and their constituents) into different solid matrices, polymeric films, and electrospun nonwovens are reviewed, especially with regard to encapsulation mechanisms and controlled release properties. Recent developments on utilizing precursor compounds of bioactive gases/volatiles to enhance their storage stability and better control their release profiles are discussed. The potential applications of these controlled release systems in AP of agri-food products are presented as well.

Features of chronic heart failure in COVID-19 pandemic

RelevanceCurrent and past coronavirus infection can provoke and aggravate the course of previous chronic heart failure by initiating the processes of thrombus formation, inflammation and fibrinogen synthesis, affecting the pleuropericardial space, increasing the load on the right heart due to pulmonary hypertension.Purpose of the studyTo identify the features of chronic heart failure after COVID-19 infection with lung damage.MaterialAn open cohort prospective study of 50 patients was carried out. Inclusion criteria: the presence of a positive brain natriuretic peptide and echocardiographic changes corresponding to systolic or diastolic dysfunction before the onset of the pandemic, signed informed consent. The diagnosis of COVID - 19 was confirmed by a positive PCR test and the presence of M and G antibodies, lung damage - by the results of computed tomography of the lungs.MethodsStandard clinical examination, quality of life questionnaire, echocardiography with measurement of cavity volume, indicators of left ventricular systolic and diastolic function, size and function of the right ventricle. The second examination was carried out one month after hospitalization.ResultsThe features of the clinical picture were an increase in shortness of breath (38 people, 86%), a decrease in exercise tolerance (40 people, 90%), an increase in chest pain (25 people, 60%), palpitations (40 people, 90%). On echocardiography, the most frequent dynamics compared to the 2019 echocardiography indicators were an increase in pressure in the pulmonary artery (44 people, 100%), the size of the right (38 people, 86%) and left ventricles (30 people, 68%), left atrium (38 people, 86%), an increase in the severity of valvular regurgitation (44 people, 100%) and a decrease in the ejection fraction within the “gray zone” (38 people, 86%). The newly emerging decrease in EF below 45% was recorded much less frequently, in 13 people (30%). In 40 (80%) patients, certain signs of deterioration of left ventricular diastolic function were revealed: dilatation of the left atrium, decrease in the mean e, increase in E/e' according to tissue Doppler ultrasonography. The TAPSE index, which characterizes the global function of the right ventricle, practically did not decrease. Frequent findings during echocardiography one month after the disease were a small amount of fluid in the pericardial cavity (30 people, 68%) and pleuropericardial adhesions.ConclusionThe clinical condition of patients with CHF in the first month after a previous infection with COVID-19 with lung involvement corresponded to a worsening of CHF with rhythm disturbances and instability of blood pressure, which on echocardiographic examination was manifested by dilatation of the heart cavities, valvular regurgitation, diastolic dysfunction of the left ventricle and increased pressure in the arteries.Funding AcknowledgementType of funding sources: None. Dynamics of echocardiography in patients

Transition to chaos in a two-sided collapsible channel flow

The nonlinear dynamics of a two-sided collapsible channel flow is investigated by using an immersed boundary-lattice Boltzmann method. The stability of the hydrodynamic flow and collapsible channel walls is examined over a wide range of Reynolds numbers $Re$ , structure-to-fluid mass ratios $M$ and external pressures $P_e$ . Based on extensive simulations, we first characterise the chaotic behaviours of the collapsible channel flow and explore possible routes to chaos. We then explore the physical mechanisms responsible for the onset of self-excited oscillations. Nonlinear and rich dynamic behaviours of the collapsible system are discovered. Specifically, the system experiences a supercritical Hopf bifurcation leading to a period-1 limit cycle oscillation. The existence of chaotic behaviours of the collapsible channel walls is confirmed by a positive dominant Lyapunov exponent and a chaotic attractor in the velocity-displacement phase portrait of the mid-point of the collapsible channel wall. Chaos in the system can be reached via period-doubling and quasi-periodic bifurcations. It is also found that symmetry breaking is not a prerequisite for the onset of self-excited oscillations. However, symmetry breaking induced by mass ratio and external pressure may lead to a chaotic state. Unbalanced transmural pressure, wall inertia and shear layer instabilities in the vorticity waves contribute to the onset of self-excited oscillations of the collapsible system. The period-doubling, quasi-periodic and chaotic oscillations are closely associated with vortex pairing and merging of adjacent vortices, and interactions between the vortices on the upper and lower walls downstream of the throat.

Cost-effective modified endoscopic vacuum therapy for the treatment of gastrointestinal transmural defects: step-by-step process of manufacturing and its advantages.

Video 1Cost-effective modified endoscopic vacuum therapy for GI transmural defects. Step-by-step process of manufacturing and potential advantages.1.Cut half gauze to the ideal size to cover only the fenestrated portion of the nasogastric tube (NGT).2.Wrap the gauze around the fenestrated portion of the NGT. The assistance of another person is important in this process.3.Cut the antimicrobial incise drape to match the size of the fenestrated portion of the NGT. Note that the incise drape is a very strong adhesive; therefore, 3 people are usually required to assemble it properly.4.Next, the suture is used to fix the gauze and drape to the NGT. Perform fixation of the modified sponge in 3 places. The first knot is in the proximal portion, just below the last fenestra of the NGT, as a marker of where the vacuum system starts. The second knot is at the distal end, to avoid migration of the modified sponge. The third knot is in the middle of the modified sponge, which is essential to serve as a guide during endoscopic placement. For example, in cases of defects without collection in which the sponge will be placed in an intraluminal position, it is ideal to place the vacuum system in the middle of the defect; in cases of intracavitary placement, it will work as a guide to how much of the modified sponge will be inside the collection.5.Finally, use a needle to make innumerable punctures in the modified sponge system to obtain adequate aspiration. An 18G needle is recommended because, in addition to having an adequate diameter, it is very sharp, which facilitates perforation of the modified sponge system.6.After creation of the modified endoscopic vacuum therapy, the functionality test is performed. Turn on the wall suction system, connect the distal end of the NGT to the tube of the canister connected on the wall, and place the NGT inside a bowl with a liquid solution. The aspiration of a large amount of liquid indicates proper functioning of the modified endoscopic vacuum therapy system.7.The device is then ready to be positioned endoscopically in the patient. After proper positioning, connect the NGT to the suction tube to avoid migration of the device upon removal of the scope.8.In addition to the cost-effective device as described, in our practice we also use wall suction to reduce costs associated with the use of the vacuum machine.9.Use the antimicrobial incise drape to seal the connection between the NGT and the suction tube to avoid leakage within the connection.10.Last, owing to instability of the negative wall pressure, a 20F intravenous catheter is connected to the tube to maintain a negative pressure between -75 and -150mmHg, as confirmed by laboratory studies performed by our group.

Stability of Open‐Top Cylindrical Steel Tanks with Primary Stiffening Ring under Wind Loading

AbstractCylindrical steel tanks are very thin shell structures and vulnerable to buckling under external pressure due to wind or partial vacuum due to rapid emptying or blocked vents when they are either empty or partially emptied. A primary stiffening ring is commonly used at or near the top of the tank wall to increase its strength against external pressure instability. Most traditional design treatments largely ignore the non‐uniform circumferential variation of the wind and treat the tank as subject only to uniform external pressure when sizing the primary stiffening ring. Moreover, the interior of the tank also experiences suction pressures due to the leeward suction on the tank. Wind tunnel tests have shown that the magnitude of these suctions can be very significant compared with the external wind pressures. This study has investigated the buckling resistance of a range of cylindrical steel storage tanks with primary stiffening rings subjected to non‐uniform wind loading modeled as harmonic variations, including the suction, using finite element analyses. A criterion for the required primary stiffening ring stiffness is developed, which is found to depend on its value relative to the stiffness of the cylindrical shell under each harmonic of wind loading. The effects of the shell‐ring stiffness ratio on the buckling capacity are studied and it is found to be a powerful measure that is critical to the design of the ring. Improved design rules are directly obtainable from this new treatment.

LMD-21. Headache Improvement Predicts Survival after CSF diversion in Leptomeningeal Disease

BackgroundLeptomeningeal carcinomatosis (LMD) is a seeding of the leptomeninges by malignant cells. Clinical, treatment and patient-related factors have been described in patients with LMD. Current data are limited by small sample size, particularly in patients undergoing ventriculoperitoneal shunting (VPS) as part of the treatment regimen.ObjectiveThis study presents the largest cohort of LMD patients in the literature undergoing cerebrospinal fluid (CSF) diversion and seeks to identify prognostic factors related to survival.MethodsA retrospective review of patients diagnosed with LMD between 2010 and 2016 at a quaternary referral center was performed. Cox proportional hazards modeling was utilized to identify variables associated with improved overall survival from LMD diagnosis. Overall survival was depicted using Kaplan-Meier methodology. Competing risk methodology was used to identify variables associated with VPS, considering death as a competing event.ResultsOf the 314 patients identified, 112 underwent VPS placement. The median overall survival from LMD diagnosis was 3.9 months (95% CI: 3.2–4.4). The presence of headaches, increased opening pressure, and gait difficulty increased the likelihood of VPS placement (all p<0.05). VPS, older age, lower Karnofsky Performance Status (KPS), higher opening pressure and CSF nucleated cell count (NCC) increased the risk of death (all p<0.05). Patients reporting headache improvement after VPS had better survival (p<0.05).ConclusionsHeadache, increased opening pressure and gait instability were associated with higher rate of VPS placement and may portend more aggressive disease. Headache improvement following VPS is a favorable prognostic sign, suggesting survival advantage for patients with hydrocephalus undergoing VPS. Age, KPS, VPS, opening pressure, CSF NCC, concomitant visceral metastases and histology-specific molecular profile impact survival.

The importance of thinking about Guillain-Barr\xe9 syndrome during the COVID-19 pandemic: a case with pure dysautonomic presentation

Guillain-Barré syndrome (GBS) is a peripheral nervous system disease caused by an immune-mediated inflammatory mechanism, usually triggered by a previous infectious process or vaccine; its typical presentation is a rapid and progressive bilateral limb hyposthenia, associated with sensory deficits and reduction or absence of osteotendinous reflexes. However, also autonomic nervous system can be involved with heart rate fluctuations, blood pressure instability, pupillary dysfunction, and urinary retention. Since the beginning of COVID-19 pandemic, GBS has been reported among neurological complications of SARS-CoV-2 infection, although etiopathological mechanisms still have to be clearly defined. We report the case of a 79-year-old man with multiple comorbidities, including diabetes, who was affected by SARS-CoV-2 interstitial pneumonia and developed dysautonomic symptoms after 10 days of hospitalization. A neurological evaluation was performed, and GBS was considered as a possible cause of the clinical manifestations. This hypothesis was confirmed by electrophysiological study and further supported, ex-juvantibus, by the satisfactory response to immunoglobulin treatment. In our opinion, this case of pure dysautonomic presentation of GBS in a SARS-CoV-2 positive patient is relevant because it suggests to consider GBS upon SARS-CoV-2 infection even if the symptoms have uncommon characteristics (e.g., pure vegetative manifestations) and if there are confounding factors which could lead to a misdiagnosis (e.g., old age, SARS-CoV-2 infection consequences and diabetes).

Symptoms of mast cell activation: The patient perspective

Symptoms of mast cell activation: The patient perspective

Metastable Helium Absorptions with 3D Hydrodynamics and Self-consistent Photochemistry. II. WASP-107b, Stellar Wind, Radiation Pressure, and Shear Instability

Abstract This paper presents simulations of the metastable helium (He*) observations of WASP-107b, so far the highest signal-to-noise ratio detection that is confirmed by three different instruments. We employ full 3D hydrodynamics coupled with coevolving nonequilibrium thermochemistry and ray-tracing radiation, predicting mass-loss rates, temperature profiles, and synthetic He* line profiles and light curves from first principles. We find that a stellar wind stronger than solar is demanded by the observed heavily blueshifted line profile and asymmetric transit light curve. Radiation pressure can be important for Lyα observations, but not He*. Our model finds that WASP-107b is losing mass at a rate of M ̇ ≃ 1.0 × 10 − 9 M ⊕ yr − 1 . Although M ̇ varies by &lt;1% given constant wind and irradiation from the host, shear instabilities still emerge from wind impacts, producing ∼10% fluctuations of He* transit depths over hour-long timescales. The common assumption that He* transit depth indicates the fluctuation of M ̇ is problematic. The trailing tail is more susceptible than planet adjacency to the shear instabilities; thus, the line profile is more variable in the blueshifted wing, while the transit light curve is more variable after midtransit. We stress that the synergy between Lyα (higher altitudes, lower density) and He* (lower altitudes, higher density) transit observations, particularly simultaneous ones, yields better understanding of planetary outflows and stellar wind properties.

RELATIONSHIP OF HYPONATREMIAAMONG PATIENTS ADMITTED IN ICU OF A TERTIARY CARE HOSPITAL IN WEST BENGAL

Introduction: Hyponatremia is a serious adverse event in the paediatric critical care population is especially complex as many patients require multiple continuous infusion and excess uid volumes due to hypovolemic shock or blood pressure instability. Aim &amp; objective:To detect hyponatremia among patients admitted in medical icu of agmc &amp; gbph and to study its etiology. Objectives 1. To nd out the proportion of patients admitted in icu having hyponatremia. 2. To study the etiology of hyponatremia in these patients. Material &amp; methods: One year starting from 1st Nov 2019 to 31st October 2020. All the patient admitted in the ICU; age more than 18 years, size was depend on the total admission within the study period in General Medicine, Murshidabad Medical college and R. G. Kar Medical college, West Bengal. Conclusion: We found that most common age group 41-60. It was found that male were predominance than female. It was found that 96(27.9%) patients had Hyponatremia We found that 22(6.4%) patients had Euvolemia, 49(14.2%) patients had Hypervolemia, 25(7.3%) patients had Hypovolemia and 248(72.1%) patients had normal.

RELATIONSHIP OF HYPONATREMIAAMONG PATIENTS ADMITTED IN ICU OF A TERTIARY CARE HOSPITAL IN WEST BENGAL

Introduction: Hyponatremia is a serious adverse event in the paediatric critical care population is especially complex as many patients require multiple continuous infusion and excess uid volumes due to hypovolemic shock or blood pressure instability. Aim &amp; objective:To detect hyponatremia among patients admitted in medical icu of agmc &amp; gbph and to study its etiology. Objectives 1. To nd out the proportion of patients admitted in icu having hyponatremia. 2. To study the etiology of hyponatremia in these patients. Material &amp; methods: One year starting from 1st Nov 2019 to 31st October 2020. All the patient admitted in the ICU; age more than 18 years, size was depend on the total admission within the study period in General Medicine, Murshidabad Medical college and R. G. Kar Medical college, West Bengal. Conclusion: We found that most common age group 41-60. It was found that male were predominance than female. It was found that 96(27.9%) patients had Hyponatremia We found that 22(6.4%) patients had Euvolemia, 49(14.2%) patients had Hypervolemia, 25(7.3%) patients had Hypovolemia and 248(72.1%) patients had normal.

Blood pressure in bipolar disorder: evidence of elevated pulse pressure and associations between mean pressure and mood instability

BackgroundBipolar disorder (BD) is associated with excess and premature cardiovascular mortality. Elevated blood pressure (BP) is a leading contributor to cardiovascular risk. However, few studies have examined BP in BD in comparison to other psychiatric disorders. Furthermore, the association between BP and mood instability is not presently clear despite increasing interest in repurposing existing antihypertensive medications as possible novel BD treatments. Thus we examined BP differences between BD and borderline personality disorder (BPD), a disorder with a similar symptom profile through chronic mood instability.MethodsA total of 106 adults (38 BD, 25 BPD, and 43 healthy controls), evaluated in the Automated Monitoring of Symptom Severity (AMoSS) study, completed a week-long home blood pressure monitoring assessment and ecological momentary assessment of mood. We examined group-wise differences in mean BP and BP variability and their association with mood instability.ResultsBD individuals had a significantly wider resting pulse pressure (40.8 ± 7.4, mmHg) compared to BPD (35.7 ± 5.3, mmHg, P = 0.03) and control participants (37.3 ± 6.3, mmHg, P = 0.036). Systolic BP was negatively associated with sad mood instability, and all measures of mean BP (systolic, diastolic, and mean arterial pressure) were negatively associated with positive mood instability.ConclusionsThis study demonstrates BP differences between BD and healthy and clinical controls that are within a normotensive range. Early pulse pressure widening may be a modifiable pathophysiological feature of BD that confers later cardiovascular risk. BP may be an important transdiagnostic predictor of mood instability and a potential explicit treatment target.

The energy of ions bombarding the vacuum chamber walls. Round beams

The ion induced pressure instability is a phenomenon, which could compromise the performance of positively charged machines. To mitigate this phenomenon, a vacuum system should be properly designed to provide sufficient pumping at correct locations, this includes an accurate gas dynamics modelling of beam vacuum chamber. The gas dynamics model requires a number of input parameters, among whose the energy of the ions bombarding vacuum chamber walls is the most critical one. This paper studies the energy of ions bombarding the vacuum chamber walls as a function of round beam parameters such as beam/bunch sizes, beam population and bunch spacing, as well as the effect of beam chamber aperture.

A parameter-free total Lagrangian smooth particle hydrodynamics algorithm applied to problems with free surfaces

This paper presents a new Smooth Particle Hydrodynamics computational framework for the solution of inviscid free surface flow problems. The formulation is based on the Total Lagrangian description of a system of first-order conservation laws written in terms of the linear momentum and the Jacobian of the deformation. One of the aims of this paper is to explore the use of Total Lagrangian description in the case of large deformations but without topological changes. In this case, the evaluation of spatial integrals is carried out with respect to the initial undeformed configuration, yielding an extremely efficient formulation where the need for continuous particle neighbouring search is completely circumvented. To guarantee stability from the SPH discretisation point of view, consistently derived Riemann-based numerical dissipation is suitably introduced where global numerical entropy production is demonstrated via a novel technique in terms of the time rate of the Hamiltonian of the system. Since the kernel derivatives presented in this work are fixed in the reference configuration, the non-physical clumping mechanism is completely removed. To fulfil conservation of the global angular momentum, a posteriori (least-squares) projection procedure is introduced. Finally, a wide spectrum of dedicated prototype problems is thoroughly examined. Through these tests, the SPH methodology overcomes by construction a number of persistent numerical drawbacks (e.g. hour-glassing, pressure instability, global conservation and/or completeness issues) commonly found in SPH literature, without resorting to the use of any ad-hoc user-defined artificial stabilisation parameters. Crucially, the overall SPH algorithm yields equal second order of convergence for both velocities and pressure.

A regressive model for dynamic impulsive instabilities during the condensation of R134a, R1234ze(E) and R1234yf refrigerants

This article presents a proposal for a regressive model describing dynamic pressure vp and temperature vT impulsive instabilities during condensation of R134a refrigerant and isomers R1234yf and R1234ze(E) in minichannels. The model was verified in relation to the obtained experimental results. In the development of the model, a dimensionless analysis using Buckingham's Π theorem was applied to obtain the dependence on dimensionless values of the propagation velocities of the pressure instability vp+ related to the acoustic speed vp and of the temperature instability vT+ related to the condensation front vFC. Experimental studies were carried out with the use of miniature tubes of circular cross-section with hydraulic internal diameter dh = 3.30, 2.30, 1.92, 1.44, and 1.40. The comparison of the computational results obtained from the model with experimental results showed a satisfactory compliance of ±25%.

Target value of mean arterial pressure in patients undergoing continuous renal replacement therapy due to acute kidney injury

BackgroundAlthough patients undergoing continuous renal replacement therapy (CRRT) due to acute kidney injury (AKI) frequently have instability in mean arterial pressure (MAP), no consensus exists on the target value of MAP related to high mortality after CRRT.MethodsA total of 2,292 patients who underwent CRRT due to AKI in three referral hospitals were retrospectively reviewed. The MAPs were divided into tertiles, and the 3rd tertile group served as a reference in the analyses. The major outcome was all-cause mortality during the intensive care unit period. The odds ratio (OR) of mortality was calculated using logistic regression after adjustment for multiple covariates. The nonlinear relationship regression model was applied to determine the threshold value of MAP related to increasing mortality.ResultsThe mean value of MAP was 80.7 ± 17.3 mmHg at the time of CRRT initiation. The median intensive care unit stay was 5 days (interquartile range, 2–12 days), and during this time, 1,227 (55.5%) patients died. The 1st tertile group of MAP showed an elevated risk of mortality compared with the 3rd tertile group (adjusted OR, 1.28 [1.03–1.60]; P = 0.029). In the nonlinear regression analysis, the threshold value of MAP was calculated as 82.7 mmHg. Patients with MAP < 82.7 mmHg had a higher mortality rate than those with ≥ 82.7 mmHg (adjusted OR, 1.21 [1.01–1.45]; P = 0.037).ConclusionsLow MAP at CRRT initiation is associated with a high risk of mortality, particularly when it is < 82.7 mmHg. This value may be used for risk classification and as a potential therapeutic target.

Obstructive sleep apnea and ambulatory blood pressure monitoring: current evidence and research gaps.

Obstructive Sleep Apnea (OSA) is a common condition characterized by intermittent collapse of the upper airway during sleep, resulting in partial (hypopnoeas) and total obstructions (apneas). These respiratory events observed in OSA may trigger multiple pathways involved in the blood pressure (BP) instability during the night and potentially influencing daytime BP as well (carry-over effects). This review provides an update about the impact of OSA and its treatments on 24-h BP control. Overall, there is growing evidence suggest that OSA is associated with higher frequency of nondipping BP pattern and nocturnal hypertension in a dose-dependent manner. The presence of nondiping BP (especially the reverse pattern) is independently associated with OSA regardless of sleep-related symptoms suggesting a potential tool for screening OSA in patients with clinical indication for performing ABPM. Beyond dipping BP, preliminary evidence associated OSA with white-coat effect and higher frequency of masked hypertension and BP variability than the control group (no OSA). Unfortunately, most of the evidence on the evidence addressing the impact of OSA treatment on BP was limited to office measurements. In the last years, data from observational and randomized studies pointed that CPAP is able to promote 24-h BP decrease especially in patients with resistant and refractory hypertension. A randomized trial suggests that CPAP is able to decrease the rate of masked hypertension as compared to no treatment in patients with severe OSA. Interestingly, nondipping BP is a good predictor of BP response to CPAP making ABPM an interesting tool for better OSA management.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ВЫРАЖЕННОСТИ ИНТЕРНЕТ-ЗАВИСИМОСТИ У ОБУЧАЮЩИХСЯ ОБРАЗОВАТЕЛЬНЫХ ОРГАНИЗАЦИЙ В РЕГИОНАХ РОССИЙСКОЙ ФЕДЕРАЦИИ

om Arkhangelsk, Nenets Autonomous Okrug, Nadym and Simferopol. The analysis of the results included two stages. At the first stage of the study, the integral and scale indicators of the severity of Internet-dependent behavior were calculated separately for each sample of students from different regions. At the second stage of the study, the group profiles of Internet-dependent behavior were evaluated by comparing the severity of each symptom of Internet addiction within a separate sample. A common trend among modern young people of older adolescence is the tendency to develop Internet-dependent behavior, regardless of the region of residence. The analysis of group profiles of Internet-dependent behavior by comparing the severity of each symptom within a separate sample allowed us to establish general and specific characteristics of the formation of Internet-dependent behavior in students from different regions of Russia. It was revealed that with a moderate level of Internet addiction severity (the average indicator for the groups is from 47.64 to 50.63 points), all the studied samples have a uniform formation of the main addictive symptoms, which are most likely in close relationship with each other. The variability of responses of respondents from the northern and southern regions was found at the level of different sensitivity to the negative consequences of excessive Internet use. There are reasons to assume that the» threshold of susceptibility» to the negative impact of the Internet environment, beyond which intrapersonal problems and health problems arise in respondents living in the Arctic zone, is lower than in respondents from the southern region. Uncomfortable natural and climatic conditions of living in the Arctic zone, associated with extremely low temperatures, light and oxygen starvation, instability of barometric pressure, as well as with specific isolation due to distance from the mainland, cause tension in all body systems, deplete adaptive reserves and have an adverse effect on health. Thus, with a high degree of probability, the revealed differences between the samples may be due to the climatic and geographical factor, as well as closely related socio-cultural and psychophysiological factors.

Acute cerebral circulation impairment associated with percutaneous coronary intervention

The article deals with generalized literature data on the current importance of the problem concerning acute cerebral ischemia occurring during percutaneous coronary interventions. Pathophysiological mechanisms of the development of acute cerebral circulation impairment are described, with their classification. Also considered are various risk factors which may cause this formidable complication, followed by describing modern methods of its surgical treatment. It is noted that the main risk factors for neurological complications appearing after revascularization of coronary arteries include age, accompanying diseases (instability of arterial pressure, diabetes mellitus, atrial fibrillation, atherorosclerotic lesions of the aorta and brachiocephalic arteries, previous stroke), as well as systolic dysfunction, leukocytosis, and a low level of cognitive function prior to operation. The development of acute cerebral circulation impairment during and after percutaneous coronary intervention is an indication for using methods of endovascular treatment. It is most appropriate to use a combination of direct percutaneous thrombectomy and a stent retriever. It is underlined in the article that removal of the thrombus form the cerebral artery is not an independent surgical procedure but rather a methodology envisaging an operation to be performed from the simplest technique to the most complicated one. As the first procedure, it is necessary to perform thrombaspiration and then, if ineffective, a second stage consisting in thrombextraction with the help of a stent retriever. Besides, in order to increase efficacy of thrombaspiration there have been worked out several techniques combining the use of direct thrombextraction and a stent retriever. Described in detail are 4 most commonly used techniques.