1,274 research outputs found

    Modelling of laminated growing biological materials

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    The continued model of the multilayered plate from a growing biological material is presented. Introducing the Airy's stress function the problem is reduced to differential equation of the fourth order. Solution of the problem is obtained for the two- layered plate with a rectangle cross-section. For some relations between the rheological coefficients of the model the governing equations are simplified and the corresponding theoretical estimations are obtained. Numerical calculations of the stress and velocity fields for the model parameters that correspond to the growing plant leaves are presented. Any difference in own growth rates of the adjacent layers leads to stretching of the tempered layer and compressing of the rapidly growing one that results in growth acceleration of the former and growth retardation of the latter. Thus the mechanical stress field can regulate coordinated growth of the laminated biological materials

    From Coulomb excitation cross sections to non-resonant astrophysical rates in three-body systems: 17^{17}Ne case

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    Coulomb and nuclear dissociation of 17^{17}Ne on light and heavy targets are studied theoretically. The dipole E1 strength function is determined in a broad energy range including energies of astrophysical interest. Dependence of the strength function on different parameters of the 17^{17}Ne ground state structure and continuum dynamics is analyzed in a three-body model. The discovered dependence plays an important role for studies of the strength functions for the three-body E1 dissociation and radiative capture. The constraints on the [s2]/[d2][s^2]/[d^2] configuration mixing in 17^{17}Ne and on pp-wave interaction in the 15^{15}O+pp channel are imposed based on experimental data for 17^{17}Ne Coulomb dissociation on heavy target.Comment: 12 pages, 13 figure

    Propensity Score-Matched Analysis of Open Surgical and Endovascular Repair for Type B Aortic Dissection

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    Objective. To identify national outcomes of thoracic endovascular aortic repair (TEVAR) for type B aortic dissections (TBADs). Methods. The Nationwide Inpatient Sample database was examined from 2005 to 2008 using ICD-9 codes to identify patients with TBAD who underwent TEVAR or open surgical repair. We constructed separate propensity models for emergently and electively admitted patients and calculated mortality and complication rates for propensity score-matched cohorts of TEVAR and open repair patients. Results. In-hospital mortality was significantly higher following open repair than TEVAR (17.5% versus 10.8%, P = .045) in emergently admitted TBAD. There was no in-hospital mortality difference between open repair and TEVAR (5.6% versus 3.3%, P = .464) for elective admissions. Hospitals performing thirty or more TEVAR procedures annually had lower mortality for emergent TBAD than hospitals with fewer than thirty procedures. Conclusions. TEVAR produces better in-hospital outcomes in emergent TBAD than open repair, but further longitudinal analysis is required

    On UHECR energy estimation algorithms based on the measurement of electromagnetic component parameters in EAS

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    Model calculations are performed of extensive air shower (EAS) component energies using a variety of hadronic interaction parameters. A conversion factor from electromagnetic component energy to the energy of ultra-high energy cosmic rays (UHECRs) and its model and primary mass dependence is studied. It is shown that model dependence of the factor minimizes under the necessary condition of the same maximum position and muon content of simulated showers.Comment: contracted version is accepted for publication in Doklady Physic

    Acute Coronary Syndrome after Percutaneous Coronary Intervention: State of the Problem and Clinical Practice Data

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    Aim. To study the prevalence, clinical and endovascular predictors, causes and timing of the development of acute coronary syndrome (ACS) in patients who had previously undergone percutaneous coronary intervention (PCI), as well as the clinical features of the disease and lipid spectrum parameters.Material and methods. The prospective study included 768 patients successively hospitalized from 01.01.2019 to 01.01.2020 in the Regional cardiovascular center, undergoing to emergency coronary angiography.Results. The main group included 768 patients who underwent emergency coronary angiography for ACS. 90 of them had previously undergone PCI (11.7%). Men prevailed (66.7%), the average age was 62 years. 25.5% of patients underwent ACS within a year after coronary stenting, the mean time from PCI to ACS was 43 months. Most often, there was ACS without ST segment elevation (80%). The results of a retrospective analysis of the first PCI showed that 89.7% of patients underwent urgent PCI, 77.8% of patients received bare metal stents. In 67.1% of patients, 1 stent was implanted, the average diameter was 3.2 mm, the average length was 22 mm. Thromboaspiration was performed in 12% of cases, predilatation in 25%, and NC postdilation in 41.3% of cases. Complications of PCI developed in 9% of patients. Stent thrombosis was diagnosed in 7.8% of cases, significant restenosis in 35.6%. Repeated stenting due to ACS was performed in 64.4% of patients, of which 74.6% received 1 stent; average diameter 3.4 mm, average length 24.0 mm. Predilatation was performed in 52.9% of cases, thromboaspiration – in 41.2%, and NC-postdilation – in 86.7% of cases. Complications of PCI developed in 10%. In addition, 99% of patients had significant dyslipidemia. The average cholesterol level was 4.91 mmol/L, the average low-density lipoprotein level was 2.94 mmol/L.Conclusion. Patients after PCI are 12% of group with ACS in clinical practice of the Regional Vascular Center. The most common predictor of recurrent atherothrombotic events is bare metal stent implantation as well as dyslipidemia

    Azimuthal modulation of the event rate of cosmic ray extensive air showers by the geomagnetic field

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    The Earth's magnetic field effect on the azimuthal distribution of extensive air showers (EAS) of cosmic rays has been evaluated using a bulk of the Yakutsk array data. The uniform azimuthal distribution of the EAS event rate is rejected at the significance level 10^(-14). Amplitude of the first harmonics of observed distribution depends on zenith angle as A1=0.2*sin^2(theta) and is almost independent of the primary energy; the phase coincides with the magnetic meridian. Basing upon the value of measured effect, the correction factor has been derived for the particle density depending on a geomagnetic parameter of a shower.Comment: 4 pages, 3 figures in ps file

    ADULT-ONSET STILL'S DISEASE: DIAGNOSIS AND TREATMENT

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    The paper describes adult-onset Still's disease (AOSD), a rare multisystemic disease of unknown etiology that is referred to as seronegative rheumatoid arthritis. It presents the major manifestations of AOSD: long-term fever, arthritis or persistent arthralgias, maculopapular eruption, seronegativity for rheumatoid factor, neutrophilic leukocytosis, and disease onset after 16 years of age, as well as additional signs: lymphadenopathy, hepatosplenomegaly, polyserositis, nasopharyngeal infection. It is noted that particular difficulties in the diagnosis of AOSD emerge when it is complicated by the hematophagocytic syndrome (HPS). The distinctive features of AOSD are the development of cutaneous and articular symptoms in practically 80% of patients and their absence in HPS. It is stated that of greater value in the diagnosis of HPS is examination of aspirate of the bone marrow than its biopsy. Most patients develop refractoriness to glucocorticoids and essential anti-inflammatory drugs. The positive results of using anakinra, rituximab, and tocilizumab are promising

    Pharmaceutical Risks of Injection Therapy: The Role of a Nurse

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    Nurse-administered injections come with a special set of risks, including such pharmaceutical factors as preparation of medicinal products in a vial prior to administration, conditions of their further storage, labelling of packages, and the need for personalised dosing of solutions for injection.The aim of the study was to analyse Russian state standard GOST R 52623.4-2015 and identify factors contributing to the risk of nursing staff’s errors in preparing, storing, and labelling of medicinal products for injection.Materials and methods. The authors analysed GOST R 52623.4-2015 Technologies for Performing Simple Medical Services of Invasive Interventions and assessed the identified risks by the FMEA method (failure modes and effects analysis).Results. The authors identified pharmaceutical risks, causes, and sources of hazardous events that occur during administration of parenteral medicinal products. The standard does not instruct readers on the order of mixing medicines in a vial and on choosing solvents for lyophilised powders. There is no labelling procedure for opened vials in the document. It does not stress the inadmissibility of pre-administration storage of a syringe/dropper with a medicinal product. The document lacks information on the need to warm the aqueous solutions that are stored in a refrigerator and/or administered at a temperature of 36–38 °С as per the package leaflet. The standard does not include a procedure for visual estimation of the volume of a solution drawn into a syringe for individual dosing of medicinal products to children. According to the FMEA risk assessment, the highest risks are posed by the order of mixing medicines in a vial and by the storage of syringes/droppers prior to administration to patients.Conclusions. To improve the safety of injection therapy, it is necessary to supplement the state standard with the identified causes of hazardous events. Nursing staff in medical organisations would benefit from in-house training on prevention of pharmaceutical risks carried out with the help of specialists in pharmaceutics and from wider involvement in discussing pharmacotherapy errors
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