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

Cranial biomechanics in basal urodeles: the Siberian salamander (Salamandrella keyserlingii) and its evolutionary and developmental implications

Developmental changes in salamander skulls, before and after metamorphosis, afect the feeding capabilities of these animals. How changes in cranial morphology and tissue properties afect the function of the skull are key to decipher the early evolutionary history of the crown-group of salamanders. Here, 3D cranial biomechanics of the adult Salamandrella keyserlingii were analyzed under diferent tissue properties and ossifcation sequences of the cranial skeleton. This helped unravel that: (a) Mechanical properties of tissues (as bone, cartilage or connective tissue) imply a consensus between the stifness required to perform a function versus the fxation (and displacement) required with the surrounding skeletal elements. (b) Changes on the ossifcation pattern, producing fontanelles as a result of bone loss or failure to ossify, represent a trend toward simplifcation potentially helping to distribute stress through the skull, but may also imply a major destabilization of the skull. (c) Bone loss may be originated due to biomechanical optimization and potential reduction of developmental costs. (d) Hynobiids are excellent models for biomechanical reconstruction of extinct early urodeles

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

Gene flow creates a mirage of cryptic species in a Southeast Asian spotted stream frog complex

Most new cryptic species are described using conventional tree- and distance-based species delimitation methods (SDMs), which rely on phylogenetic arrangements and measures of genetic divergence. However, although numerous factors such as population structure and gene flow are known to confound phylogenetic inference and species delimitation, the influence of these processes is not frequently evaluated. Using large numbers of exons, introns, and ultraconserved elements obtained using the FrogCap sequence-capture protocol, we compared conventional SDMs with more robust genomic analyses that assess population structure and gene flow to characterize species boundaries in a Southeast Asian frog complex (Pulchrana picturata). Our results showed that gene flow and introgression can produce phylogenetic patterns and levels of divergence that resemble distinct species (up to 10% divergence in mitochondrial DNA). Hybrid populations were inferred as independent (singleton) clades that were highly divergent from adjacent populations (7%-10%) and unusually similar (<3%) to allopatric populations. Such anomalous patterns are not uncommon in Southeast Asian amphibians, which brings into question whether the high levels of cryptic diversity observed in other amphibian groups reflect distinct cryptic species-or, instead, highly admixed and structured metapopulation lineages. Our results also provide an alternative explanation to the conundrum of divergent (sometimes nonsister) sympatric lineages-a pattern that has been celebrated as indicative of true cryptic speciation. Based on these findings, we recommend that species delimitation of continuously distributed "cryptic" groups should not rely solely on conventional SDMs, but should necessarily examine population structure and gene flow to avoid taxonomic inflation

A little frog leaps a long way: compounded colonizations of the Indian Subcontinent discovered in the tiny Oriental frog genus Microhyla (Amphibia: Microhylidae)

Frogs of the genus Microhyla include some of the world’s smallest amphibians and represent the largest radiation of Asian microhylids, currently encompassing 50 species, distributed across the Oriental biogeographic region. The genus Microhyla remains one of the taxonomically most challenging groups of Asian frogs and was found to be paraphyletic with respect to large-sized fossorial Glyphoglossus. In this study we present a time-calibrated phylogeny for frogs in the genus Microhyla, and discuss taxonomy, historical biogeography, and morphological evolution of these frogs. Our updated phylogeny of the genus with nearly complete taxon sampling includes 48 nominal Microhyla species and several undescribed candidate species. Phylogenetic analyses of 3,207 bp of combined mtDNA and nuDNA data recovered three well-supported groups: the Glyphoglossus clade, Southeast Asian Microhyla II clade (includes M. annectens species group), and a diverse Microhyla I clade including all other species. Within the largest major clade of Microhyla are seven well-supported subclades that we identify as the M. achatina, M. fissipes, M. berdmorei, M.superciliaris, M.ornata, M.butleri, and M.palmipes species groups. The phylogenetic position of 12 poorly known Microhyla species is clarified for the first time. These phylogenetic results, along with molecular clock and ancestral area analyses, show the Microhyla—Glyphoglossus assemblage to have originated in Southeast Asia in the middle Eocene just after the first hypothesized land connections between the Indian Plate and the Asian mainland. While Glyphoglossus and Microhyla II remained within their ancestral ranges, Microhyla I expanded its distribution generally east to west, colonizing and diversifying through the Cenozoic. The Indian Subcontinent was colonized by members of five Microhyla species groups independently, starting with the end Oligocene—early Miocene that coincides with an onset of seasonally dry climates in South Asia. Body size evolution modeling suggests that four groups of Microhyla have independently achieved extreme miniaturization with adult body size below 15 mm. Three of the five smallest Microhyla species are obligate phytotelm-breeders and we argue that their peculiar reproductive biology maybe a factor involved in miniaturization. Body size increases in Microhyla—Glyphoglossus seem to be associated with a burrowing adaptation to seasonally dry habitats. Species delimitation analyses suggest avast underestimation of species richness and diversity in Microhyla and reveal 15–33 undescribed species. We revalidate M. nepenthicola, synonymize M. pulverata with M. marmorata, and provide insights on taxonomic statuses of a number of poorly known species. Further integrative studies, combining evidence from phylogeny, morphology, advertisement calls, and behavior will result in a better systematic understanding of this morphologically cryptic radiation of Asian frogs