External Contour Research Articles

Fabrication and properties of PLA/nano-HA composite scaffolds with balanced mechanical properties and biological functions for bone tissue engineering application

Abstract Repair of critical bone defects is a challenge in the orthopedic clinic. 3D printing is an advanced personalized manufacturing technology that can accurately shape internal structures and external contours. In this study, the composite scaffolds of polylactic acid (PLA) and nano-hydroxyapatite (n-HA) were manufactured by the fused deposition modeling (FDM) technique. Equal mass PLA and n-HA were uniformly mixed to simulate the organic and inorganic phases of natural bone. The suitability of the composite scaffolds was evaluated by material characterization, mechanical property, and in vitro biocompatibility, and the osteogenesis induction in vitro was further tested. Finally, the printed scaffold was implanted into the rabbit femoral defect model to evaluate the osteogenic ability in vivo. The results showed that the composite scaffold had sufficient mechanical strength, appropriate pore size, and biocompatibility. Most importantly, the osteogenic induction performance of the composite scaffold was significantly better than that of the pure PLA scaffold. In conclusion, the PLA/n-HA scaffold is a promising composite biomaterial for bone defect repair and has excellent clinical transformation potential.

Müllerian Duct Anomalies: Role in Fertility and Pregnancy.

Müllerian duct anomalies (MDAs) have important implications for the reproductive health of female patients. In patients with both infertility and recurrent pregnancy loss, the incidence of MDAs is as high as 25%. Congenital uterine anomalies are often only part of a complex set of congenital anomalies involving the cervix, vagina, and urinary tract. Multiple classification systems for MDAs exist, each with different criteria that vary most for the diagnosis of septate uterus. Recognizing the features that guide clinical management is essential for interpretation. Identification of an MDA should prompt evaluation for associated urinary tract anomalies. In patients with infertility who seek to use assisted reproductive technologies such as intrauterine insemination, recognition of MDAs may have an affect on reproductive success, particularly in patients who have an incomplete and clinically occult septum that divides the cervix. Two-dimensional US is the first-line modality for evaluating the uterus and adnexa. Three-dimensional (3D) US or MRI may help to visualize the external uterine fundal contour and internal indentation of the endometrial cavity, which are two morphologic characteristics that are keys to the diagnosis of congenital uterine anomalies. Hysterosalpingo contrast-enhanced US may be performed in conjunction with 3D US to evaluate uterine morphologic characteristics, the endometrial cavity, and tubal patency in a single examination. MRI helps to characterize rudimentary uteri in patients with müllerian hypoplasia and allows assessment for ectopic ureters, abnormally positioned ovaries, or associated deep infiltrative endometriosis. Online supplemental material is available for this article. ©RSNA, 2021.

The surface-dwelling from layer I of Mira site: Main features and interpretations

Situated in Dnieper valley, in the central part of continental Ukraine, the site of Mira yields two well-preserved Palaeolithic occupation levels, possessing features of true living floors. The uppermost layer I, presenting remains of autumn-winter seasonal occupation, is dated to between 32,000 and 31,000cal BP. Layer I contains EUP assemblage combining the technological and morphological features of local Middle and Upper Palaeolithic. Layer I includes many various objects, like pits, postholes, hearths, bone and ashes accumulations etc. Remains of sub-circular surface-dwelling construction with an area of about 14.5 m2 were recognised in the uppermost layer due to numerous postholes and specific characteristics of the living floor. Micro-stratigraphic and spatial features recognise two distinct construction elements, namely the external irregular spherical contour and the inscribed slightly asymmetrical rectangular contour. An entrance, associated with four ashy lenses of likely smoke hearths, was recognised oriented east-wards toward a current river channel. This outer, close to the entrance, zone of construction contains numerous flints, in particular, flint tools, thousands tiny debris and waste-flakes of tool resharpening and reshaping, as well as bone ornaments and ornamented bone pieces, and also a fragment of a human molar. On the contrary, the practically free lithics though containing plenty of burned organic material, the back part of the construction, likely separated from the outer zone by a special partition, was seemingly served as a sleeping zone. It is possible to conclude about the recovery of remains of permanent carcass surface cylindrical dwelling that found analogies in ethnographical records. Keeping in mind the age and geographical position, we deal with the earliest instance of complicate surface-dwelling construction currently known in the steppe area of the East European plain.

Normal fetal development of the cervical, thoracic, and lumbar spine: A postmortem study based on magnetic resonance imaging.

Before evaluating spinal pathology, it is essential to have knowledge of the normal spinal development at different gestational ages. This study aims to characterize normal spinal growth in human fetuses during the second and third trimesters. Postmortem 3.0T magnetic resonance imaging (MRI) was performed on 55 fetuses at 17-42 gestational weeks by using three-dimensional T2-weighted sequences. Morphological changes and quantitative measurements of the fetal spine were assessed. The correlation between centrum ossification center volume (COCV) and gestational age was investigated. The cervical, thoracic, and lumbar COCVs showed a positive relationship with gestational age (p<0.05). No gender differences were found in the volumetric development of the cervical, thoracic, and lumbar centrum ossification centers (COCs). The average volumetric growth rate per COC was larger in the lumbar spine than in the cervical and thoracic spine. The L1-L5 COCVs also showed a linear positive relationship with gestational age. Postmortem 3.0T MRI clearly demonstrated spinal changes in external contour and internal structure with gestational age. These findings expand our understanding of the early growth pattern of the human spine and could be further used to assess the developmental conditions of the fetal spine.

DEFINITION AND ANALYSIS OF THE GOALS OF EXTERNAL PARTICIPANTS IN THE FORMATION OF THE PARENT COMPANY PROJECT PORTFOLIO

Purpose of research: To show that the practice of functioning of production industries indicates the relevance of conducting pre-project analysis and improving its quality in terms of identifying the interests of all participants in the formation of the project portfolio of the parent company; to improve the identification of conflict situations; to suggest approaches to goal-setting and pre-project analysis of the goals of the subjects of the formation of the project portfolio. The results. The external contour of the subjects influencing the formation of the project portfolio of the parent company is highlighted. Tools for conducting pre-project analysis and determining the objectives of the subjects are proposed. The objectives of the subjects are identified and systematized. A mathematical description of both qualitative and quantitative goals is developed and proposed. Their analysis is carried out and typical conflict situations that arise during the formation of a project portfolio are identified. An approach to resolving the identified conflicts is proposed. The practical significance it is manifested by increasing the accuracy of the formation of a portfolio of projects for the medium and long term, timely identification and resolution of conflict situations and the formation of informed decisions by the manager about the need to expand/modernize/reorganize production.

Fractal dimension of external linear contour of human cerebellum (magnetic resonance imaging study)

Fractal analysis is a method of mathematical analysis, which provides quantitative assessment of the spatial configuration complexity of the anatomical structures and may be used as a morphometric method. The purpose of the study was to determine the values of the fractal dimension of the outer linear contour of human cerebellum by studying the magnetic resonance images of the brain using the authors’ modification of the caliper method and compare to the values determined using the box counting method. Brain magnetic resonance images of 30 relatively healthy persons aged 18-30 years (15 men and 15 women) were used in the study. T2-weighted digital magnetic resonance images were studied. The midsagittal MR sections of the cerebellar vermis were investigated. The caliper method in the author’s modification was used for fractal analysis. The average value of the fractal dimension of the linear contour of the cerebellum, determined using the caliper method, was 1.513±0.008 (1.432÷1.600). The average value of the fractal dimension of the linear contour of the cerebellum, determined using the box counting method, was 1.530±0.010 (1.427÷1.647). The average value of the fractal dimension of the cerebellar tissue as a whole, determined using the box counting method, was 1.760±0.006 (1.674÷1.837). The values of the fractal dimension of the outer linear contour of the cerebellum, determined using the caliper method and the box counting method were not statistically significantly different. Therefore, both methods can be used for fractal analysis of the linear contour of the cerebellum. Fractal analysis of the outer linear contour of the cerebellum allows to quantify the complexity of the spatial configuration of the outer surface of the cerebellum, which is difficult to estimate using traditional morphometric methods. The data obtained from this study and the methodology of the caliper method of fractal analysis in the author’s modification can be used for morphometric investigations of the human cerebellum in morphological studies, as well as in assessment of cerebellar MR images for diagnostic purposes.

Assessment of the Quality of the Combined Radiotherapy Plans for Patients with Advanced Cervical Cancer

Purpose: To assess the quality of planning for the combined radiotherapy of patients with advanced cervical cancer (cervical cancer). To assess the impact of taking into account not only the external, but also the internal wall of the organ of risk during contouring on the magnitude of the radiation load on the organ of risk (OR). Estimate the total dose to the OR from the remote and intracavitary components.Material and methods: The planning quality assessment was carried out for three technologies of remote exposure, namely: 3DCRT, IMRT and IMRT in the rotational RapidArc mode. Radiotherapy was performed on linac Clinac iX models (Varian, USA) with photon energy of 6 MeV, intracavitary RT (IRT) — on a MicroSelectron apparatus with a 192Ir source. The calculation was carried out on the treatment planning system Eclipse (Varian, USA) and Oncentra Brachy.Results: The evaluation of the quality of conformal radiotherapy planning was carried out in 69 patients with locally advanced cervical cancer 2b–3b stages according to homogeneity and dose conformance indexes in target volumes and OR in combined radiation therapy programs. The best values of the indices of homogeneity and conformity were obtained with the IMRT technology and 3DCRT. The values of the conformity index CI for PTV for the IMRT technology has advantages in terms of doses to OR. For a group of 94 patients, an analysis of dose loads on the rectum, bladder was carried out with only the external contour of the OR and taking into account the inner wall. For 37 patients, the total values of doses to OR for combined RT were evaluated.Conclusion: The quantitative advantages of homogeneity and conformance indices for the tumor and dose loads in OR of 3D CRT and IMRT technologies for patients with cervical cancer 2b–3b are revealed. We removed from the use of technology RapidArc for this group of patients. The advantages of contouring with or without thickness are not revealed. The contouring for all the mentioned cases of technology can be carried out along the outer contours of the OR.

Elasticity Approach to Predict Shape Transformation of Functionally Graded Mechanical Metamaterial under Tension

The re-entrant structures are among the simple unit cell designs that have been widely used in the design of mechanical metamaterials. Changing the geometrical parameters of these unit cell structures, their overall elastic properties (i.e., elastic stiffness and Poisson’s ratio), can be simultaneously tuned. Therefore, different design strategies (e.g., functional gradient) can be implemented to design advanced engineering materials with unusual properties. Here, using the theory of elasticity and finite element modeling, we propose a fast and direct approach to effectively design the microarchitectures of mechanical metamaterials with re-entrant structures that allow predicting complex deformation shapes under uniaxial tensile loading. We also analyze the efficiency of this method by back calculating the microarchitectural designs of mechanical metamaterials to predict the complex 1-D external contour of objects (e.g., vase and foot). The proposed approach has several applications in creating programmable mechanical metamaterials with shape matching properties for exoskeletal and soft robotic devices.

Collagen Nanofilm-Coated Partially Deproteinized Bone Combined With Bone Mesenchymal Stem Cells for Rat Femoral Defect Repair by Bone Tissue Engineering.

The advantages of good biocompatibility, low degradation and low antigenicity of collagen, and the osteogenic differentiation characteristics of bone mesenchymal stem cells (BMSCs) were used to promote the recovery of bone defects using partially deproteinized bone (PDPB) by bone tissue engineering (BTE). The BMSCs were identified by examining their potential for osteogenic, lipogenic, and chondrogenic differentiation. The prepared pure PDPB was ground into bone blocks 4 × 2 × 2 mm in size, which were divided into the following groups: PDPB group, PDPB + collagen group, PDPB + collagen + BMSC group, PDPB with a composite collagen nanofilm, and BMSCs injected into the tail vein. At 2, 4, 6, and 8 weeks after surgery, the effects of the implants in the different groups on bone defect repair were continuously and dynamically observed through x-ray examination, gross specimen observation, histological evaluation, and microvascularization detection. Postoperative x-ray examination and gross specimen observation revealed that, after 4 to 8 weeks, the external contour of the graft was gradually weakened, and the transverse comparison showed that the absorption of the graft and fusion of the defect were more obvious in PDPB + collagen + BMSC group than in PDPB group and PDPB + collagen group, and the healing was better (P < 0.05). Hematoxylin and eosin staining of histological sections showed very active proliferation of trabecular hematopoietic cells in groups PDPB + collagen + BMSC and PDPB + collagen. Masson's trichrome staining for evaluation of bone defect repair showed that the mean percent area of collagen fibers was greater in PDPB + collagen + BMSC group than in the PDPB group, with degradation of the scaffold material and the completion of repair. Immunofluorescence staining showed significantly enhanced expression of the vascular marker CD31 in group C (P < 0.05). The proposed hybrid structure of the collagen matrix and PDPB provides an ideal 3-dimensional microenvironment for patient-specific BTE and cell therapy applications. The results showed that collagen appeared to regulate MSC-mediated osteogenesis and increase the migration and invasion of BMSCs. The combination of collagen nanofilm and biological bone transplantation with BMSC transplantation enhanced the proliferation and potential of the BMSCs for bone regeneration, successfully promoting bone repair after implantation at the defect site. This method may provide a new idea for treating clinical bone defects through BTE.

Numerical simulation on slump test of fresh concrete based on lattice Boltzmann method

In this paper, the rheological mechanism of fresh concrete material was investigated and the method of evaluating its rheological property was optimized by combining the slump test of five groups of fresh concrete and lattice Boltzmann method (LBM). The rheological parameters of fresh concrete samples based on Herschel-Bulkley (H–B) model and Bingham model were obtained by rheometer and equation derivation with nonlinear and linear fitting approaches. The comparison of Bingham and H–B models in the simulation results of the slump test demonstrated that the H–B model was more accurate in expressing the rheological characteristics of the fresh concrete. In the Bingham model, the errors of slump s, spread sf and the time of spread reaching 500 mm T500 ranged from 2.00% to 39.29%. The errors of s and sf in the H–B model were less than 2%, and the error of T500 was about 5%. Afterwards, the results of the slump test were predicted based on the H–B model. The effects of rheological parameters (power-law index consistency index and yield stress) on velocity, viscosity, shear strain rate, flow rate and external contour were revealed.

Characterising the Mould Rectification Process for Designing Scoliosis Braces: Towards Automated Digital Design of 3D-Printed Braces

The plaster-casting method to create a scoliosis brace consists of mould generation and rectification to obtain the desired orthosis geometry. Alternative methods entail the use of 3D scanning and CAD/CAM. However, both manual and digital design entirely rely on the orthotist expertise. Characterisation of the rectification process is needed to ensure that digital designs are as efficient as plaster-cast designs. Three-dimensional scans of five patients, pre-, and post-rectification plaster moulds were obtained using a Structure Mark II scanner. Anatomical landmark positions, transverse section centroids, and 3D surface deviation analyses were performed to characterise the rectification process. The rectification process was characterised using two parameters. First, trends in the external contours of the rectified moulds were found, resulting in lateral tilt angles of 81 ± 3.8° and 83.3 ± 2.6° on the convex and concave side, respectively. Second, a rectification ratio at the iliac crest (0.23 ± 0.04 and 0.11 ± 0.02 on the convex and concave side, respectively) was devised, based on the pelvis width to estimate the volume to be removed. This study demonstrates that steps of the manual rectification process can be characterised. Results from this study can be fed into software to perform automatic digital rectification.

The Unequal Taxonomic Signal of Mosquito Wing Cells.

Simple SummaryMosquitoes of the genus Aedes include important vectors of human disease viruses, including dengue, chikungunya and Zika. Surveillance programs used to detect and control these pests need accurate, fast and low-cost techniques to track the primary target and monitor possible re-infestations. Geometric morphometrics of mosquito wings is a convenient tool in mosquito species identification, but this method requires a complete wing in good condition for maximum accuracy. In this study, we investigate the amount of taxonomic signal provided by shape analysis of the internal cells of the wing. We show that (i) the internal cells of the wing provide differing amounts of taxonomic information, and (ii) the taxonomic signal of a given cell depends on the species under comparison. Since some of these cells are very informative, our study suggests that even damaged wings may provide key taxonomic information to differentiate among species found in mixed species surveillance collections.Accurate identification of mosquito species is critically important for monitoring and controlling the impact of human diseases they transmit. Here, we investigate four mosquito species: Aedes aegypti, Ae. albopictus, Ae. scutellaris and Verrallina dux that co-occur in tropical and subtropical regions, and whose morphological similarity challenges their accurate identification, a crucial requirement in entomological surveillance programs. Previous publications reveal a clear taxonomic signal embedded in wing cell landmark configuration, as well as in the external contour of the wings. We explored this signal for internal cells of the wings as well, to determine whether internal cells could uniformly provide the same taxonomic information. For each cell to be tentatively assigned to its respective species, i.e., to measure the amount of its taxonomic information, we used the shape of its contour, rather than its size. We show that (i) the taxonomic signal of wing shape is not uniformly spread among internal cells of the wing, and (ii) the amount of taxonomic information of a given cell depends on the species under comparison. This unequal taxonomic signal of internal cells is not related to size, nor to apparent shape complexity. The strong taxonomic signal of some cells ensures that even partly damaged wings can be used to improve species recognition.

The effect of carbon fibre treatment couch with and without immobilisation devices on radiotherapy dose calculation using three different planning algorithms and photon beam energies

AbstractIntroduction:The objective of radiotherapy immobilisation devices is to improve the reproducibility of patient positioning during treatment sessions. The inclusion of these devices in the treatment protocol may increase the skin dose. In practice, these devices are not systematically taken into account in the dose calculation.Material and methods:In this study, the dosimetric effects of the carbon fibre couch iBEAM Evo Extension 415, with and without three different immobilisation devices (a Klarity Breastboard R610-2ECF, a Bionix Butterfly Board and CIVCO Vac-Lok vacuum bag), were calculated and evaluated on the dose calculation for conformal three-dimensional radiation therapy. The measurements were carried out by comparing the measured dose with the one calculated for three different algorithms, FFT convolution, fast superposition and superposition algorithms, which are implemented in Xio treatment planning system (TPS).Results:Dosimetric tolerance levels have been respected for specific dose calculations, which do not include the fibre couch with or without immobilisation devices. Errors of up to 8% in the dose calculation were obtained for the beams passing through the fibre couch and the breast board base support region.Conclusion:According to the significant attenuation differences of the beam by the fibre couch and immobilisation devices, it was concluded that ignoring the device in the dose calculation can change patient’s skin and target doses. The fibre couch and immobilisation device should be included within external body contour to account for the TPS calculation algorithms dose attenuation.

Dosimetric effects of supine immobilization devices on the skin in intensity-modulated radiation therapy for breast cancer: a retrospective study

BackgroundThe dose perturbation effect of immobilization devices is often overlooked in intensity-modulated radiation therapy (IMRT) for breast cancer (BC). This retrospective study assessed the dosimetric effects of supine immobilization devices on the skin using a commercial treatment planning system.MethodsForty women with BC were divided into four groups according to the type of primary surgery: groups A and B included patients with left and right BC, respectively, who received 50 Gy radiotherapy in 25 fractions after radical mastectomy, while groups C and D included patients with left and right BC, respectively, who received breast-conservation surgery (BCS) and 40.05 Gy in 15 fractions as well as a tumor bed simultaneous integrated boost to 45 Gy. A 0.2-cm thick skin contour and two sets of body contours were outlined for each patient. Dose calculations were conducted for the two sets of contours using the same plan. The dose differences were assessed by comparing the dose-volume histogram parameter results and by plan subtraction.ResultsThe supine immobilization devices for BC resulted in significantly increased skin doses, which may ultimately lead to skin toxicity. The mean dose increased by approximately 0.5 and 0.45 Gy in groups A and B after radical mastectomy and by 2.7 and 3.25 Gy in groups C and D after BCS; in groups A–D, the percentages of total normal skin volume receiving equal to or greater than 5 Gy (V5) increased by 0.54, 1.15, 2.67, and 1.94%, respectively, while the V10 increased by 1.27, 1.83, 1.36, and 2.88%; the V20 by 0.85, 1.87, 2.76, and 4.86%; the V30 by 1.3, 1.24, 10.58, and 11.91%; and the V40 by 1.29, 0.65, 10, and 10.51%. The dose encompassing the planning target volume and other organs at risk, showed little distinction between IMRT plans without and with consideration of immobilization devices.ConclusionsThe supine immobilization devices significantly increased the dose to the skin, especially for patients with BCS. Thus, immobilization devices should be included in the external contour to account for dose attenuation and skin dose increment.Trial registrationThis study does not report on interventions in human health care.

Dosimetric Assessment of a High Precision System for Mouse Proton Irradiation to Assess Spinal Cord Toxicity.

The uncertainty associated with the relative biological effectiveness (RBE) in proton therapy, particularly near the Bragg peak (BP), has led to the shift towards biological-based treatment planning. Proton RBE uncertainty has recently been reported as a possible cause for brainstem necrosis in pediatric patients treated with proton therapy. Despite this, in vivo studies have been limited due to the complexity of accurate delivery and absolute dosimetry. The purpose of this investigation was to create a precise and efficient method of treating the mouse spinal cord with various portions of the proton Bragg curve and to quantify associated uncertainties for the characterization of proton RBE. Mice were restrained in 3D printed acrylic boxes, shaped to their external contour, with a silicone insert extending down to mold around the mouse. Brass collimators were designed for parallel opposed beams to treat the spinal cord while shielding the brain and upper extremities of the animal. Up to six animals may be accommodated for simultaneous treatment within the restraint system. Two plans were generated targeting the cervical spinal cord, with either the entrance (ENT) or the BP portion of the beam. Dosimetric uncertainty was measured using EBT3 radiochromic film with a dose-averaged linear energy transfer (LETd) correction. Positional uncertainty was assessed by collecting a library of live mouse scans (n = 6 mice, two independent scans per mouse) and comparing the following dosimetric statistics from the mouse cervical spinal cord: Volume receiving 90% of the prescription dose (V90); mean dose to the spinal cord; and LETd. Film analysis results showed the dosimetric uncertainty to be ±1.2% and ±5.4% for the ENT and BP plans, respectively. Preliminary results from the mouse library showed the V90 to be 96.3 ± 4.8% for the BP plan. Positional uncertainty of the ENT plan was not measured due to the inherent robustness of that treatment plan. The proposed high-throughput mouse proton irradiation setup resulted in accurate dose delivery to mouse spinal cords positioned along the ENT and BP. Future directions include adapting the setup to account for weight fluctuations in mice undergoing fractionated irradiation.

Investigation on Image-Based Digital Method for Identification on Polyester/Cotton Fiber Category

As of today, it still remains a considerable challenge to identify the polyester/cotton fiber category in the textile industry. Based on shape coefficient analysis, a novel comprehensively-designed and appropriately-developed digital cross-section image processing method was proposed to improve the identification accuracy of polyester/cotton fiber. A self-developed microscope image acquisition system was established, so as to digitalize the cross section of fiber. Aimed at the gray scale enhancement, binarization and opening operation, a set of image preprocessing algorithms was developed. Initially, the edge detection algorithm was used to identify the external contour of the cross-section of fiber. Subsequently, the cross section of fiber was separated by watershed segmentation algorithm, and that, the false fiber was removed by area elimination algorithm. Finally, the shape coefficient was calculated to identify polyester/cotton fiber category. The experimental results indicated that the data and results obtained by the newly-designed digital analysis method which is based on shape coefficient in this paper can be used to identify the polyester/cotton fiber category, showing a broad application prospect in textile quality control, including the developments of concerned equipments, methods and standards.

Communication aspects of cooperation in the forestry waste processing cluster

The article is devoted to the study of communications in the cluster for forest waste processing as a factor and indicator of cooperation development. The article provides an overview of 4 groups of clusters with ecological, forestry, biotechnological and agricultural specialization; in total 21 clusters are studied. The cluster communication field is considered through a number of general scientific approaches. An algorithm for systematizing and replicating the experience of successful communication building in a cluster is proposed. The communication field of clusters using renewable natural resources is reviewed. From the perspective of an outside researcher, the conditions for effective and free interaction in the considered cases have not been created. The used communication practices are summarized. The target characteristics of the cluster communication model as an open network with an external and internal contour, with public involvement are formulated. The dependence of the functional content of communications on the stage of evolution in the cluster, on the ratio of the goals of innovation and efficiency is shown. The achievement of innovative cluster-specific effects is determined by the nature of relationships between participants and largely depends on the organization of the cluster’s communication field.

Development of an algebraic fractional step scheme for the primitive formulation of the compressible Navier-Stokes equations

In this work we address the compressible Navier-Stokes equations written in the so-called primitive formulation. The proposed methodology is a finite-element solver based on a fractional step scheme in time, which allows to uncouple the calculation of the problem unknowns providing important savings in computational cost. In addition, we include a stabilization technique within the Variational Multi-Scale framework and, in particular, we consider orthogonal and dynamic definitions for the subscales. In order to overcome any wave reflections which may arise in aeroacoustic simulations at the low compressibility regime, we present a method for enforcing boundary conditions based on a combination of a zero order non-reflecting condition plus the weak imposition of Dirichlet boundary conditions over the external contours. Several representative benchmark flow simulations are performed, which demonstrate the suitability of the proposed algorithm for the subsonic regime.

Biomechanical affect of percutaneous transforaminal endoscopic discectomy on adjacent segments with different degrees of degeneration:a finite element analysis

To investigate the biomechanical affect of percutaneous transforaminal endoscopic discectomy(PTED) on adjacent segments with different degrees of degeneration and related risk of adjacent segment diseases (ASD) caused by this operation. A healthy male adult volunteer was selected, and the lumbosacral vertebra image data was obtained by CT scan, and the external contour of the bone structure was reconstructed. On this basis, the external contour of the bone structure was fitted by using the smooth curve in 3D-CAD software, and the complete three-dimensional finite element modelof the non degenerate L3-S1 segment and the degenerative models of the L3-L4 and L5-S1 segment were drawn forward. In L4, L5 segment simulating PTED surgery through the removal of right part of articular process and nucleus pulposus and anulus fibrosus. After PTED was simulated in the L4-L5 segment and the risk of ASD has been evaluated by six changes of biomechanical indicators in flexion, extension, left and right lateral bending, left and right axial rotation conditions. In the finite element model without adjacent segmental disc degeneration, the annulus fibrosus von Mises stress and intradiscal pressure of the PTED model showed only a slight increase under most stress conditions, and a slight decrease in a few conditions, and there was no significant change trend before and after surgery. In the original degenerated adjacent segment disc model, the biomechanical indicators related to disc degeneration in the pre- and post-PTED model showed significant deterioration, leading to an increased risk of potential adjacent spondylopathy. PTED surgery will not lead to the significant deterioration of postoperative biomechanical environment of non-degeneration adjacent intervertebral discs, and the original degeneration of adjacent intervertebral discs is a important risk factor for ASD.

THE MODEL OF THE INTERCULTURAL ADAPTATION ECOSYSTEM OF UNIVERSITIES AS AN ELEMENT OF STRATEGIC DEVELOPMENT

The tasks of increasing the international competitiveness and export of Russian education within the framework of national development priorities are inextricably linked with the need to create a favorable environment for the adaptation of international students based on ecosystem and stakeholder approaches. The development of an integral and multidimensional model of the Russian intercultural adaptation ecosystem for universities and other educational organizations should take place with full recognition of the values of external and internal internationalization in all activities in order to form long-term key competencies. The model of the intercultural adaptation ecosystem should become a matrix and, in a way, a framework solution from the point of view of the strategic development of universities in the global world, taking into account rethinking and sophistication of their mission as a social institution in global partnership.The article offers a comprehensive vision of a model of an intercultural adaptation ecosystem of the educational organization with two contours – internal and external. The internal contour includes four components: values, practices, processes and structures. The external contour of the intercultural adaptation ecosystem of an educational organization also includes four components: inner Russian educational collaborations, international cooperation, interaction with national and cultural communities, and recommendations for authorities.The authors offer a detailed analysis of the factors and priorities of the necessary organizational changes in Russian universities in the context of the tasks of intercultural literacy skills’ strategic development for all participants and stakeholders of the educational process with further transformation into the competence of cultural intelligence.