Double difiusion in Ar-N2 Binary gas system at the constant value of temperature gradient

An experimental study of the diffusion-gravitational convection transition boundary in an Ar-N2 binary system at different pressures and a constant temperature gradient is performed. It is shown that the diflusion is replaced by the gravitational convection at a pressure p 0:5 MPa. In terms of the stability theory, a perturbation boundary line is determined, dividing the Rayleigh numbers plane into the regions of the diflusion and the convective mass transfer. The experimental data agree well with the theoretical values

Magneto-Conductance Anisotropy and Interference Effects in Variable Range Hopping

We investigate the magneto-conductance (MC) anisotropy in the variable range hopping regime, caused by quantum interference effects in three dimensions. When no spin-orbit scattering is included, there is an increase in the localization length (as in two dimensions), producing a large positive MC. By contrast, with spin-orbit scattering present, there is no change in the localization length, and only a small increase in the overall tunneling amplitude. The numerical data for small magnetic fields $B$, and hopping lengths $t$, can be collapsed by using scaling variables $B_\perp t^{3/2}$, and $B_\parallel t$ in the perpendicular and parallel field orientations respectively. This is in agreement with the flux through a `cigar'--shaped region with a diffusive transverse dimension proportional to $\sqrt{t}$. If a single hop dominates the conductivity of the sample, this leads to a characteristic orientational `finger print' for the MC anisotropy. However, we estimate that many hops contribute to conductivity of typical samples, and thus averaging over critical hop orientations renders the bulk sample isotropic, as seen experimentally. Anisotropy appears for thin films, when the length of the hop is comparable to the thickness. The hops are then restricted to align with the sample plane, leading to different MC behaviors parallel and perpendicular to it, even after averaging over many hops. We predict the variations of such anisotropy with both the hop size and the magnetic field strength. An orientational bias produced by strong electric fields will also lead to MC anisotropy.Comment: 24 pages, RevTex, 9 postscript figures uuencoded Submitted to PR

Forming A Pedagogue’s Research Competences in Innovative Educational Environment

Changes that take place in different spheres of life in Russia (economic, political, social, cultural) determine new requirements to the goals, values, functions of education in providing the development and self-realization of students. A graduate of a modern school should master a complex of information and research skills, and have critical and creative thinking. Research methodology. The orientation of education towards the growth of a student as a person, bearer of certain individual peculiarities, and activity subject may be of use only if an effective strategy of pedagogic work is developed. Such a strategy should be scientifically grounded on the basic principles of modern approaches implemented in pedagogy and psychology: humanistic, personality-, activity- and competence-oriented. Research results. Four spheres of a pedagogue’s professional activity in an innovative educational environment have been distinguished: sphere of analysis, synthesis and mastering pioneering pedagogic experience; sphere of popularization and initial practical use of pioneering pedagogic experience and advanced developments; sphere of the improvement of professional skills and realization of creative potential of a teacher; sphere of innovative processes in the system of education. Discussion. The essence of a pedagogue’s research activity is conditioned by the functions, which are based on the following factors: optimization of the teaching and educational process; specifically, structured controlled cognitive process; processes of self-improvement, self-instruction and selfeducation, self-realization; mastering professional pedagogic activity of a new level. Conclusion. Four levels of the development of a teacher’s research competences have been distinguished: basic, empiric (local and initiative), productive (tactical), and constructive (strategic)

Double Diffusion in Ar−N2Ar-N_2 Binary Gas System at the Constant Value of Temperature Gradient

An experimental study of the "diffusion-gravitational convection" transition boundary in an $Ar-N_2$ binary system at different pressures and a constant temperature gradient is performed. It is shown that the diffusion is replaced by the gravitational convection at a pressure p ≈ 0.5 MPa. In terms of the stability theory, a perturbation boundary line is determined, dividing the Rayleigh numbers plane into the regions of the diffusion and the convective mass transfer. The experimental data agree well with the theoretical values

POTENTIAL OF ULTRASOUND-GUIDED LUMBAR FACET RADIOFREQUENCY DENERVATION

The aim of the study was to evaluate the possibility of US navigation for Radiofrequency denervation (RFD) of the lumbar facets.Material and methods. The authors performed a prospective controlled cohort study which included 50 patients with chronic pain syndrome who underwent RFD LIII-SI facets on both sides. The main group (US) included 25 patients, who underwent US guided navigation with FScontrol of the correct placement of the cannula prior to ablation. In the control group (FS) the RFD was performed only under FS control. Patients were selected after preliminary test block of medial branch with 50% pain reduction from the baseline. Patients with overweight, spinal deformity, pronounced degenerative changes, spinal stenosis and developmental anomalies were not included in the study. For the evaluation of outcomes, the numeric pain scale NRS-11 and the Oswestry index (ODI) were used, the accuracy of the cannula position was assessed and factors determining the accuracy were searched.Results. As a result of the intervention, there was a significant decrease of NRS-11 and ODI criteria in both groups (p<0.001), a positive outcome was achieved in 18 (72%) of US patients and 16 (64%) of FS patients, p = 0.564. Of the 200 attempts to position the cannula under the ultrasound control, 169 (84.5%) were successful, in most cases (187 out of 200, 93.5%) at least 3 attempts were required to reposition the cannula. The average time for performing the procedure under the ultrasound control was 47.3±1.13 minutes. The facet angle and procedure level were defined as predictors of the cannula positioning accuracy, odds ratio 0.93 (95% CI 0.894–0.963) and 0.51 (95% CI 0.32–0.805), respectively.Conclusion. RFD of lumbar facet under ultrasound navigation allows to achieve a relatively high accuracy of the cannula position into the zone of passage of the articular branch. The navigation capabilities are reduced at the level of LV and SI vertebrae due to structural features of the joints, namely coronary orientation of the facets with the formation of a narrow space between the transverse and upper articular process, which create difficulties for scanning. The disadvantage of ultrasound control is the lengthy procedure and the need for repeated reinsertion of the cannulae worsening the patient’s tolerance of procedure

OUTCOMES OF TRANSFORAMINAL ENDOSCOPIC DISCECTOMY FOR LUMBOSACRAL DISC HERNIATION

Introduction. Lumbar disc herniation is a frequent pathology and surgical target. Endoscopic discectomy becomes more popular due to minimally invasive surgical technique. There is a deficit of scientific papers dedicated to analysis of potential for endoscopic discectomy depending on the specifics of spinal anatomy and degenerative changes.The purpose of the study was to evaluate the efficacy of transforaminal endoscopic discectomy (TED) in comparison with microdiscectomy (MD) and to specify factors determining complications and failures.Materials and methods. The authors performed randomized controlled study where main group of patients included data on prospective examination of 101 patients after TED procedure for lumbar intervertebral disc herniation. Age of patients ranged from 19 to 81 years with average of 41,4±12,6 years. Control group included data of retrospective examination of 153 patients that were operated by the same surgeon in the period from 201 till 2104 with microdiscectomy procedure. Age of patients ranged from 18 to 77 years with average of 47,8±11,3 years. Inclusion criteria were as follows: surgical procedure at the same level of the primary intervertebral herniation. Exclusion criteria were: degenerative spinal canal stenosis, spondylolisthesis, spine deformity.Results. Clinical outcomes after TED demonstrated no difference from MD procedure. No factors of significant influence on outcomes after surgical procedure were observed. The main group was characterized by more cases of revisions and conversions of endoscopic into open procedures (13,9%) which was related to mistakes in transforaminal approach due to features of intervertebral joints and foramina anatomy resulting in impossibility to achieve adequate spinal canal decompression.Conclusion. Transforaminal endoscopic discectomy is an effective and safe method of lumbar intervertebral herniation treatment. Complications and failures during learning curve of endoscopic procedure are associated with technique drawbacks as well as with mistakes in planning and performing the approach. Congenital alignment of lumbar spine with specific patterns of facets and foramina anatomy dictate technical difficulties with transforaminal approach

COLD PLASMA NUCLEOPLASTY VERSUS RADIOFREQUENCY ANNULOPLASTY FOR DISCOGENIC PAIN SYNDROME: COMPARATIVE ANALYSIS OF EFFICACY

Introduction. The intervertebral disc is considered the main source of pain syndrome in degenerative diseases  of the spine. The methods of laser, mechanical and cold plasma nucleotomy are widely used in Russia and are included into the system of high-tech medical care. The most promising annuloplasty methods are less known and have only recently been introduced into the national surgical practice. patients’ selection criteria and surgical procedure choice are not clearly defined and the information about annuloplasty in the national literature is practically not presented.Purpose — to conduct the comparative analysis for efficiency of paracentetic nucleoplasty and radiofrequency annuloplasty for discogenic pain and to identify the factors determining the surgery outcomes.Materials and Methods. The authors performed a retrospective cohort study. patients were divided into two groups: 107 patients underwent cold plasma nucleoplasty (Np), 72 patients received radiofrequency annuloplasty (RFap) at one or several levels. evaluation of outcomes was based on the dynamics of the NRS-11 digital pain scale and the Oswestry index (OdI). Positive results were recognized with decrease of NRS-11 index by 50% (or NRc-11 <4) and OdI by 20% from the original (or OdI <20%) when the outcome was preserved for 6 or more months postoperatively. To identify the factors influencing the outcome the authors assessed the following criteria prior to surgery: clinical findings (acute, chronic or recurrent pain syndrome), severity and prevalence of disc degeneration at the level of intervention and in adjacent segments, the use of other interventional diagnostic methods for excluding other sources of pain. Results. In results of the procedures the authors reported a decrease of indices in both groups (p<0.001) in the absence of significant differences between the groups (p = 0.672). However, but the number of positive outcomes in the RFap group was higher than in the Np group — 49 (68.1%) and 55 (51.4%) respectively. Significant prognostic factors in the Np group were acute character of the pain syndrome (Spearman ρ = 0.252, p = 0.014), fewer operated levels (ρ = -0.304, p<0.001); in both groups such factors were failure of other procedures (Np ρ = 0.413, p<0.001; RFap ρ = 0.464, p<0.001) and the degree of disc degeneration of adjacent segments (Np ρ = -0.387, p<0.001; RFap ρ = -0.297, p<0.001). With regression analysis the best results were observed under the criteria “failure of other procedures”,  for Np (OR 0.77 at 95% cI (0.682-0.857) and for RFap (OR 0.81, 95% cI (0.701-0.924)). Conclusion. Both methods of cold plasma nucleoplasty and radiofrequency annuloplasty demonstrate positive and similar outcomes provided the discogenic character of the pain syndrome has been defined correctly. The most significant is the exclusion of other sources of pain by diagnostic blockades, especially for patients with chronic pain syndrome and advanced multi-level lesion of the spine segments