Level Of Compression Research Articles

Characterization of high-strength concrete under monotonic and fatigue mode II loading with actively controlled level of lateral compression

The fatigue behavior of plain concrete has been studied for decades, usually under compressive or tensile loading. Shear loading (mode II) has been almost completely neglected in the past. In contrast to cylindrical compression tests, this type of loading offers the advantage of precise load determination and a small, well-defined fracture surface. This paper presents a comprehensive experimental campaign of 66 shear tests, which was conducted to systematically investigate the monotonic, cyclic, and fatigue response of high-strength concrete under mode II loading. Since the material behavior under shear stress is strongly dependent on the concurrent lateral compressive stress, a new test setup was developed which allows simultaneous control of compressive and shear loading. One potential utilization for these shear fatigue tests is the validation of a promising hypothesis that suggests that the development of fatigue damage in concrete at subcritical load levels is governed by a cumulative measure of shear sliding. The qualitative influence of the lateral compressive loading on the displacement and damage development, fracture behavior, and fatigue life is analyzed and discussed. The test results indicate that there is no influence of the lateral compressive load level on the shear fatigue life, as long as the increase in shear strength is considered. Furthermore, concrete under mode II loading seems to have a longer fatigue life than concrete in standard cylindrical specimens under compressive loading.

Research on the edge effect of 7075 aluminium alloy damaged aircraft component strengthened by laser shock peening

Laser shock peening (LSP) is a promising surface strengthening process in the field of aircraft maintenance. However, unreasonable residual stress distribution often exists at the edge of the damaged aircraft component strengthened by LSP, which results in a significant decrease in strengthening effect of LSP. To explore the residual stress distribution after LSP in the edge region of components and reveal the influence of edge effects on deformation and inducing residual stress, the finite element (FE) models of LSP on 7075 aluminum alloy was established based on ABAQUS. The reliability of the FE model was verified by comparing the experiment and simulation results. The residual stress distribution in the edge and center region after LSP were analyzed. The results show that the edge effect enhances the flow of material to the edge and introduces tensile stress in this direction, thereby reducing the overall residual compressive stress level in the edge region. The influence range of edge effect on residual stress distribution is about 70% of the laser spot diameter. Besides, edge effects reinforce the phenomenon of residual stress holes, which results in a reduction of the maximum value by 109.2MPa. The influence of edge effect can be solved by multi surfaces LSP.

Method of compression and ensuring the fidelity of video images in infocommunication networks

Subject research in the article is the methods of compressing video images under conditions of ensuring the desired level of their fidelity in the delivery process using infocommunication networks. The goal is to develop methods of encoding video images for increasing the level of their compression in the conditions of ensuring required reliability. Task: to substantiate the approach regarding the structural clusterization of transformed video segments in the conditions of preserving their reliability; to develop a method of structural and statistical coding of transformants in the spectral-cluster space; conduct a comparative evaluation of the effectiveness of various methods of encoding video segments. The methods used: mathematical models for estimating the amount of statistical and structural redundancy in the clustered spectral space of video segments; methods of statistical coding. The following results have been obtained. The potential effectiveness of representing a transformant in clustered space by the number of series of units in binary description of their components has been substantiated. A method of structural-statistical coding in the spectral-cluster space has been created. The basic component of this technological approach is the evaluation of the estimates regarding the potential ability to eliminate various types of redundancy in the current cluster. Here, the amount of redundancy is reduced considering the statistical and structural features of the cluster. The comparative evaluation revealed the advantages of the created method over coding methods in standardized platforms. The advantage is achieved in terms of the peak signal-to-noise ratio by at least 30%. and in terms of a compression ratio by an average of 12 %. Conclusions. The scientific novelty of the obtained results is as follows: for the first time, a method of structural-statistical coding of video segments in spectral space based on their clusterization has been created. The differences of the method lie in the fact that the component of the transformant is simultaneously interpreted as an element of the statistical and combinatorial cluster space; the potential capabilities of eliminating various types of redundancy in the clustered transformant are considered. This provides an increase in the level of compression of video images for a given level of reliability.

Flow Characteristics of Fibrous Gas Diffusion Layers Using Machine Learning Methods

The material characteristics of gas diffusion layers are relevant for the efficient operation of polymer electrolyte fuel cells. The current state-of-the-art calculates these using transport simulations based on their micro-structures, either reconstructed or generated by means of stochastic geometry models. Such transport simulations often require high computational resources. To support material characterization using artificial-intelligence-based methods, in this study, a convolutional neural network was developed. It was trained with results from previous transport simulations and validated using five-fold cross-validation. The neural network enables the permeability of paper-type gas diffusion layers to be predicted. A stochastic arrangement of the fibers, four types of binder distributions, and compression of up to 50% are also considered. The binder type and compression level were features inherent to the material but were not the subject of the training. In this regard, they can be seen as features hidden from the training process. Nevertheless, these characteristics were reproduced with the proposed machine learning model. With a trained machine learning model, the prediction of permeability can be performed on a standard computer.

The synergy of synchrotron imaging and convolutional neural networks towards the detection of human micro-scale bone architecture and damage

The growing health and economic burden of bone fractures, their intricate multiscale features and the existing knowledge gaps in the comprehension of micro-scale bone damage occurrence make fracture diagnosis a challenging issue. In this scenario, deep-learning and artificial intelligence embody the new frontier of healthcare system, by overcoming the subjectivity of clinicians in the analysis of medical images. However, the preliminary attempts in exploiting the power of machine learning algorithms such as neural networks are still limited to bone macro-scale, while there is an evident lack in their application to smaller scales, where damage starts nucleating. Currently, speculations at the micro-scale are only feasible with the aid of high-resolution imaging techniques, that are particularly time consuming in terms of output images analysis. In this context, this works aims at combining the visualization of the micro-crack propagation mechanism with the promising application of convolutional neural networks. The implemented artificial intelligence tool is based for the first time on a large number of human synchrotron images coming from healthy and osteoporotic femoral heads tested under micro-compression. The designed convolutional neural networks are able to automatically detect lacunae and micro-cracks at different compression levels with high accuracy levels; indeed, with the baseline setup, networks achieve more than 0.99 level of accuracy for both cracks and lacunae, and more than 0.87 of the meanIoU adopted as validation metric. This approach is particularly encouraging for the development of powerful recognition system to comprehend bone micro-damage initiation and propagation, paving the way to the application of machine learning studies to bone micromechanics. This could be additionally crucial for future patient specific micro-scale observations to be related to the clinical practice.

Clinical and radiographic characteristics of increased signal intensity of the spinal cord at the vertebral body level in patients with cervical myelopathy

BackgroundIncreased signal intensity (ISI) is usually recognized at the disc level of the responsible lesion in the patients with cervical myelopathy. However, it is occasionally seen at the vertebral body level, below the level of compression. We aimed to investigate the clinical significance and the radiographic characteristics of ISI at the vertebral body level. MethodsThis retrospective study included 135 patients with cervical spondylotic myelopathy who underwent surgery and with local ISI. We measured the local and C2-7 angle at flexion, neutral, and extension. We also evaluated the local range of motion (ROM) and C2-7 ROM. The patients were classified into group D (ISI at disc level) and group B (ISI at vertebral body level). ResultsThe prevalence was 80.7% (109/135) and 19.3% (26/135) for groups D and B, respectively. Local angle at flexion and neutral were more kyphotic in group B than in group D. The local ROM was larger in group B than in group D. Moreover, C2-7 angle at flexion, neutral and extension were more kyphotic in group B than in group D. Two years later, local angle at flexion, neutral, and extension were also kyphotic in group B than group D; however, local and C2-7 ROM was not significantly different between the two groups. There was no significant difference of clinical outcomes 2 years postoperatively between both groups. ConclusionsGroup B was associated with the kyphotic alignment and local greater ROM, compared to group D. As the spinal cord is withdrawn in flexion, the ISI lesion at vertebral body might be displaced towards the disc level, which impacted by the anterior components of the vertebrae. ISI at the vertebral body level might be related to cord compression or stretching at flexion position. This should be different from the conventionally held pincer-mechanism concept.

Surgical results for cervical spondylotic myelopathy with inconsistent between deep tendon reflex findings and magnetic resonance imaging findings

BackgroundTo evaluate the surgical results of patients with cervical spondylotic myelopathy (CSM) with inconsistency between deep tendon reflex findings and cervical magnetic resonance imaging (MRI) findings and to analyze the differences between patients with good and poor surgical outcomes. MethodsWe evaluated 50 subjects with CSM (30 males, 20 females; mean age: 70.4 years) who underwent posterior surgery and were followed for at least 1 year postoperatively. Matched CSM was defined as a consistent preoperative neurological pattern determined by deep tendon reflex and cervical MRI T2-weighted high-signal intramedullary area or stenosis in the most cranial compression levels. A lack of consistency was classified as unmatched CSM. Recovery rate (RR) according to Japanese Orthopaedic Association (JOA) scoring preoperatively and at 1 year postoperatively were compared between the groups. ResultsThe matched and unmatched CSM group included 27 subjects (13 males, 14 females; mean age: 68.2 years) and 23 subjects (17 males, 6 females; mean age: 72.8 years), respectively. RR was significantly higher in the matched CSM group (56.1 ± 3.7 % vs 36.8 ± 2.7 %; p = 0.002). Unmatched CSM was significantly associated with a lower RR independently of sex, patient age, surgical procedure, preoperative JOA score, diagnosis levels, and complication of diabetes. ConclusionsPostoperative JOA score RR was significantly diminished among unmatched CSM patients comprising of 46% of cases. Some patients with unmatched CSM had multiple levels of spinal canal stenosis, foraminal stenosis, and peripheral neuropathy, suggesting that surgical results were poorer than those of matched CSM.

Seismic performance of precast wide beam-column connections with asymmetrical anchorage reinforcement details

This study aims to investigate the seismic performances of precast concrete (PC) wide beam-column connections under reversed cyclic loading, in which the precast beam width is 1.5 times larger than that of column. Experimental program consists of a monolithic reinforced concrete (RC) specimen and two PC specimens with unique connection details. To avoid reinforcement congestions and also to secure emulative connecting performances, the PC specimens were integrated by asymmetrically placed connecting bars anchored into the column panel zone, and their anchorage end details were chosen as a key testing variable. Detailed numerical models were developed to identify the failure mechanisms and key influencing factors of the cyclic responses of PC wide beam-column connections. It appeared that the precast wide beam-column connections with asymmetrical anchorage details can also provide the so-called emulative seismic performance as a monolithic connection. Significant effects of bond-slip behaviors of the anchorage connecting reinforcements in the joint and axial compression level of the column on the seismic performance of PC wide beam-column connections were also identified by the nonlinear numerical simulations.

Magnetic resonance image segmentation of the compressed spinal cord in patients with degenerative cervical myelopathy using convolutional neural networks.

Spinal cord segmentation is the first step in atlas-based spinal cord image analysis, but segmentation of compressed spinal cords from patients with degenerative cervical myelopathy is challenging. We applied convolutional neural network models to segment the spinal cord from T2-weighted axial magnetic resonance images of DCM patients. Furthermore, we assessed the correlation between the cross-sectional area segmented by this network and the neurological symptoms of the patients. The CNN architecture was built using U-Net and DeepLabv3 + and PyTorch. The CNN was trained on 2762 axial slices from 174 patients, and an additional 517 axial slices from 33 patients were held out for validation and 777 axial slices from 46 patients for testing. The performance of the CNN was evaluated on a test dataset with Dice coefficients as the outcome measure. The ratio of CSA at the maximum compression level to CSA at the C2 level, as segmented by the CNN, was calculated. The correlation between the spinal cord CSA ratio and the Japanese Orthopaedic Association score in DCM patients from the test dataset was investigated using Spearman's rank correlation coefficient. The best Dice coefficient was achieved when U-Net was used as the architecture and EfficientNet-b7 as the model for transfer learning. Spearman's rs between the spinal cord CSA ratio and the JOA score of DCM patients was 0.38 (p = 0.007), showing a weak correlation. Using deep learning with magnetic resonance images of deformed spinal cords as training data, we were able to segment compressed spinal cords of DCM patients with a high concordance with expert manual segmentation. In addition, the spinal cord CSA ratio was weakly, but significantly, correlated with neurological symptoms. Our study demonstrated the first steps needed to implement automated atlas-based analysis of DCM patients.

Characterization of intra-tissue strain fields in articular cartilage explants during post-loading recovery using high frequency ultrasound

This study aims to demonstrate the potential of ultrasound elastography as a research tool for non-destructive imaging of intra-tissue strain fields and tissue quality assessment in cartilage explants. Osteochondral plugs from bovine patellae were loaded up to 10, 40, or 70 N using a hemi-spherical indenter. The load was kept constant for 15 min, after which samples were unloaded and ultrasound imaging of strain recovery over time was performed in the indented area for 1 h. Tissue strains were determined using speckle tracking and accumulated to LaGrangian strains in the indentation direction. For all samples, strain maps showed a heterogeneous strain field, with the highest values in the superficial cartilage under the indenter tip at the bottom of the indent and decreasing values in the deeper cartilage. Strains were higher at higher load levels and tissue recovery over time was faster after indentation at 10 N than at 40 N and 70 N. At lower compression levels most displacement occurred near the surface with little deformation in the deep layers, while at higher levels strains increased more evenly in all cartilage zones. Ultrasound elastography is a promising method for high resolution imaging of intra-tissue strain fields and evaluation of cartilage quality in tissue explants in a laboratory setting. In the future, it may become a clinical diagnostic tool used to identify the extent of cartilage damage around visible defects.

The value of dynamic MRI in cervical spondylotic myelopathy: About 24 cases.

Dynamic magnetic resonance imaging (MRI) of the cervical spine is extremely useful in assessing pathological changes at the spinal cord, vertebrae, discs, ligaments and facet joints. We attempted to document the radiological changes that the cervical spine undergoes during dynamic maneuvers and the effects of Dynamic MRI in management of cervical myelopathy, emphasizing on the changes in treatment protocol effected by the new findings discovered. Our work is based on 24 consecutive patients with cervical spondylotic myelopathy had cervical MR imaging in neutral position, in flexion and extension of the cervical spine between January 2021 and December 2021. The result found the mean age was 57.9 years (range 26-85 years). Among these 24 patients, there were 11 males and 13 females. Total number of levels of compression were 47 and the additional levels of involvement were 17. Additional levels of compression were noted in 12 patients, among these 17 new levels, 7 were in the posterior and 10 in the anterior. The most affected level was C5C6 with 16 cases. All additional levels of compression were noted in extension; Reduction of the cervical canal was observed in 20 patients only in extension. In the bending sequences we have noticed an increase of the canal diameter in 3 patients. The location of the compression is in 15 cases anterior, 2 cases posterior and 5 cases are mixed anterior and posterior Surgery was considered in 17 patients. Anterior procedures were 11 (ACDF/corpectomy and fusion) and Posterior surgeries were 6 (laminoplasty/laminectomy), and. The rest of the patients did not require surgery and was conservatively treated. A change of the signal was found in 3 patients during the acquisition in extension position a. Most studies have shown a reduction of the root canal with an increase of the compression level, which was the case in our study. MRI is a useful tool for diagnosis of CM, it does not give an exact idea as to which is the offending level in a multilevel compression that requires surgery. Even the approach and procedure cannot be decided on a static examination and hence are subject to significant interpractitioner the role of extension MRI in determining cervical compression levels. Thus, dynamic cervical spine MRI should be an important investigation before we decide to write off surgical treatment in patients with cervical myelopathy and cord signal changes without definitive compression on static MRI. Flexion and extension MRI is an important tool for decision making and planning appropriate management in cervical compressive myelopathy.

Trigeminal afferents sense locomotion-related meningeal deformations.

The trigeminal sensory innervation of the cranial meninges is thought to serve a nociceptive function and mediate headache pain. However, the activity of meningeal afferents under natural conditions in awake animals remains unexplored. Here, we used two- and three-dimensional two-photon calcium imaging to track the activity of meningeal afferent fibers in awake mice. Surprisingly, a large subset of afferents was activated during non-noxious conditions such as locomotion. We estimated locomotion-related meningeal deformations and found afferents with distinct dynamics and tuning to various levels of meningeal expansion, compression, shearing, and Z-axis motion. Further, these mechanosensitive afferents were often tuned to distinct directions of meningeal expansion or compression. Thus, in addition to their role in headache-relatedpain, meningeal sensory neurons track the dynamic mechanical state of the meninges under natural conditions.

Prospective study of surgical outcomes of cervical myelopathy based on its etiology, duration of affection and radiological patterns of compression

<p><strong>Background: </strong>Cervical spondylotic myelopathy (CSM) is considered the commonest cause of spinal cord dysfunction in individuals above 55 years of age and if left untreated, permanent cord damage may occur. This could contribute to increased dependence and reduced quality of life in older individuals. A prospective cohort study done in patients with cervical myelopathy who were admitted and operated after considering inclusion and exclusion criteria.<strong></strong></p><p><strong>Methods</strong>: A prospective cohort study done in patients with cervical myelopathy who were admitted and operated after considering inclusion and exclusion criteria. Total 30 patients included in study. patients were operated according to patterns of compression. Anterior/posterior decompression SOS instrumentation was done according to POC. Pre-op and post-op Nurick’s grading, pre-op and post-op modified Japanese orthopaedics association (mJOA) scores were used for comparison. Patients were followed up for period of 1 year from surgical intervention. Recovery rate calculated using preop and post op mJOA scores.</p><p><strong>Results</strong>: Overall satisfactory surgical outcome found in patients of cervical myelopathy<sub>, </sub>out of 30 patients, 9 patients of pattern of compression I (POC I) had recovery rate (RR) of (91.6±7.8) , 8 patients of POC II had RR of (78.4±14.8), 6 patients of POC III had RR of (73.5±11.1), 4 patients of POC IV had RR of (74.9±29.2), 3 patients of POC IVv had RR of (80.4±4.1).the assessment of the final outcome was done using mJOA scoring system and Nurick’s grading system.</p><p><strong>Conclusions: </strong>Anterior cervical discectomy and fusion (ACDF) for POC I (one- or two-level anterior cord compression) and POC II (one or two levels of anterior and posterior cord compression) give good surgical outcome. Cervical laminectomy and SOS instrumentation is recommended for POC III (3 levels of anterior cord compression), IV (3 or more levels of anterior compression and development of narrow canal with multiple posterior compression) and IV variant (similar to POC IV with one or two levels, being more significant than the others).earlier diagnosis, prompt radiological investigations, individualizing surgical protocol, proper surgical techniques and proper follow-up evaluation are key in management of patients of cervical myelopathy.</p>

Modulation of Biofilm Mechanics by DNA Structure and Cell Type.

Deoxyribonucleic acid (DNA) evolved as a tool for storing and transmitting genetic information within cells, but outside the cell, DNA can also serve as "construction material" present in microbial biofilms or various body fluids, such as cystic fibrosis, sputum, and pus. In the present work, we investigate the mechanics of biofilms formed from Pseudomonas aeruginosa Xen 5, Staphylococcus aureus Xen 30, and Candida albicans 1408 using oscillatory shear rheometry at different levels of compression and recreate these mechanics in systems of entangled DNA and cells. The results show that the compression-stiffening and shear-softening effects observed in biofilms can be reproduced in DNA networks with the addition of an appropriate number of microbial cells. Additionally, we observe that these effects are cell-type dependent. We also identify other mechanisms that may significantly impact the viscoelastic behavior of biofilms, such as the compression-stiffening effect of DNA cross-linking by bivalent cations (Mg2+, Ca2+, and Cu2+) and the stiffness-increasing interactions of P. aeruginosa Xen 5 biofilm with Pf1 bacteriophage produced by P. aeruginosa. This work extends the knowledge of biofilm mechanobiology and demonstrates the possibility of modifying biopolymers toward obtaining the desired biophysical properties.

Predicting the Influence of Shear on the Seismic Response of Bridge Columns

In the seismic design and evaluation of bridges, a method is required for determining the shear strength of reinforced concrete columns to avoid brittle shear failures. In addition, detailed design and evaluation often require predictions of the complete hysteretic response of bridge columns to accurately model the nonlinear dynamic response of the bridge. Predictions of the shear strength of columns using the provisions of the AASHTO Specifications are compared with the reversed-cyclic loading test results of shear-critical columns. It is found that the Simplified Procedure results in very conservative predictions of the seismic shear strength. The General Procedure provides conservative and more accurate predictions of the seismic shear strength. It is suggested that the AASHTO reduction factor on the concrete contribution resisting shear for low compressive axial load levels be removed. Nonlinear finite element analysis predictions are made for a selection of rectangular and circular columns tested in reversed-cyclic loading and are compared with the experimental results. The ability of nonlinear finite element analysis to predict the reversed-cyclic loading responses of columns with a wide range of variables and having different failure modes is demonstrated.

Morphological Changes of Deep Extensor Neck Muscles in Relation to the Maximum Level of Cord Compression and Canal Compromise in Patients With Degenerative Cervical Myelopathy.

Cross-sectional study. To examine the relationship between morphological changes of the deep extensor neck muscles in patients with degenerative cervical myelopathy (DCM) and the level of maximum spinal cord compression (MSCC) and canal compromise (MCC). A secondary objective was to examine the relationship between muscle morphological changes with neck pain and functional scores related to neck pain and interference. A total of 171 patients with DCM were included. Total cross-sectional area (CSA), functional CSA (fat free area, FCSA), ratio of FCSA/CSA (fatty infiltration) and asymmetry of the multifidus (MF) and semispinalis cervicis (SCer) together, and cervical muscle as a group (eg, MF, SCer, semispinalis capitis, splenius capitis) were obtained from T2-weighted axial MR images at mid-disc, at the level of maximum cord compression and the level below. The relationship between the muscle parameters of interest, MSCC, MCC and functional scores including the Neck Disability Index (NDI) was assessed using multivariate linear regression models, adjusting for age, body mass index and sex. Greater MF + Scer fatty infiltration was associated with greater MCC (P = .032) and MSCC (P = .049) at the same level. Greater asymmetry in MF + SCer CSA was also associated with greater MCC (P = .006). Similarly, greater asymmetry in FCSA and FCSA/CSA of the entire extensor muscle was associated with greater MCC (P = .011, P = .013). There was a negative association between asymmetry in FCSA MF + SCer, FCSA/CSA MF + SCer and FCSA/CSA group muscles with NDI score at the level below. Greater MCC is associated with increased fatty infiltration and greater asymmetry of the deep cervical muscles in patients with DCM. A negative association between muscle asymmetry and NDI scores was also observed which has implications for clinical prediction around axial neck pain.

Prospective Evaluation of Stereotactic Body Radiation Therapy (SBRT) for Patients with Metastatic Epidural Spinal Cord Compression

<h3>Purpose/Objective(s)</h3> Metastatic epidural spinal cord compression (MESCC) can be very painful and disabling. We hypothesized that an initial fraction of SBRT would provide rapid decompression and allow for potential dose escalation via a follow up treatment. Our primary objective was to assess the feasibility of a staged SBRT approach to provide short-interval treatment response. Secondary endpoints included pain control and quality of life (QoL). <h3>Materials/Methods</h3> This single institution, prospective study enrolled non-surgical candidates with MESCC from 07/2015 to 02/2018. Those with spine instability (SINS>12), bony retropulsion, or radiosensitive histologies were excluded. After baseline imaging (MRIpre), patients received SBRT (10-16 Gy) and a short interval MRI within 2-3 weeks (MRI1). Subsequently, patients could receive an additional treatment at the discretion of the treating physician. A second MRI was completed 8-10 weeks post-tx (MRI2). QoL questionnaires and pain scores were obtained at all time points. The primary endpoint was the smallest cord-disease distance (CDD) in the axial plane and the thecal sac patency (TSP), defined as the thecal sac area at the level of maximal compression divided by the average thecal sac area one level above and below. Secondary endpoints included pain scores and QoL using the Functional Assessment of Cancer Therapy – General (FACT-G). Statistical comparisons utilized the Wilcoxson signed-rank test. <h3>Results</h3> 22 patients were enrolled in the study and received SBRT. The most common primary diagnoses were lung (36%) and prostate (32%) cancer. The most common initial SBRT doses were 16 Gy (41%) and 14 Gy (36%). 12 patients completed all 3 scans and 3 other patients completed 2 scans (MRIpre and either MRI1 or MRI2). No patient received a second,adaptive fraction of radiation (due to lost to follow up, systemic progression, or no local progression). TSP significantly increased on MRI1 (median change 9%, IQR 1%-28%, p = 0.034) and on MRI2 (median change 24%, IQR 12-32%, p = 0.002). CDD did not increase significantly on MR1 (median change 0.0 mm, IQR 0-0.3 mm, p = 0.125) but did on MRI2 (median change 1.5 mm, IQR 0-1.8 mm, p = 0.001). On radiology report, 23% had disease improvement on MRI1, all of whom received 16 Gy. 64% had disease improvement on MRI2. No patients progressed neurologically. There was a numerical decrease in best and worst pain score over time (p=0.093). FACT-G scores did not change significantly over time. There were no grade 3 or greater toxicities related to RT. <h3>Conclusion</h3> Single-fraction SBRT can provide rapid decompression of epidural disease safely and quickly. Radiosurgical decompression can be a feasible alternative to surgery in patients with MESCC, especially as a large segment of such patients are non-surgical candidates. A follow up study comparing SBRT to 3D CRT is being planned.

Piezoresistive Properties of Natural Hydraulic Lime Binary Pastes with Incorporated Carbon-Based Nanomaterials under Cyclic Compressive Loadings.

Natural Hydraulic Limes (NHL) are extensively used for the restoration of Monuments of Cultural Heritage, often combined with pozzolanic materials, such as natural pozzolans and metakaolin etc. In the present study, five (5) different cases of binary lime-based pastes composed of a specific type of NHL (NHL5) and metakaolin as pozzolanic addition were examined, that were reinforced with carbon nanostructures, namely graphene and carbon nanotubes. For the first time in restoration mortars, the incorporation of carbon nanostructures was investigated, aiming to produce materials with adequate piezoresistive response, so that they have the potential to be exploited for in situ structural health monitoring. The compressive strength, flexural strength, electrical resistance and piezoresistive response of the composite pastes was examined. The results showed that all modified carbon nanostructures lead to a significant reduction in electrical resistance. The pastes reinforced with 2D nanostructures (graphene family) displayed up to 30% increase in compressive strength and the pastes reinforced with 1D nanostructures (carbon nanotubes) displayed enhanced flexural strength (up to 100% increase). Piezoresistivity was attained for almost all investigated pastes, nevertheless the graphene oxide (GO) was considered as optimal reinforcement as the sensing ability of such pastes was found to be almost proportional to the applied compressive load level.

Deep learning prediction of two-dimensional ocean dynamics with wavelet-compressed data.

This study addresses the challenge represented by the application of deep learning models to the prediction of ocean dynamics using datasets over a large region or with high spatial or temporal resolution In a previous study by the authors of this article, they showed that such a challenge could be met by using a divide and conquer approach. The domain was in fact split into multiple sub-regions, which were small enough to be predicted individually and in parallel with each other by a deep learning model. At each time step of the prediction process, the sub-model solutions would be merged at the boundary of each sub-region to remove discontinuities between consecutive domains in order to predict the evolution of the full domain. This approach led to the growth of non-dynamical errors that decreased the prediction skill of our model. In the study herein, we show that wavelets can be used to compress the data and reduce its dimension. Each compression level reduces by a factor of two the horizontal resolution of the dataset. We show that despite the loss of information, a level 3 compression produces an improved prediction of the ocean two-dimensional data in comparison to the divide and conquer approach. Our method is evaluated on the prediction of the sea surface height of the most energetic feature of the Gulf of Mexico, namely the Loop Current.

Tissue integration and biodegradation of soft tissue substitutes with and without compression: an experimental study in the rat

ObjectivesTo analyze the influence of compression on tissue integration and degradation of soft tissue substitutes.Material and methodsSix subcutaneous pouches in twenty-eight rats were prepared and boxes made of Al2O3 were implanted and used as carriers for soft tissue substitutes: a collagen matrix (MG), two volume-stable collagen matrices (FG/MGA), and a polycaprolactone scaffold(E). The volume-stable materials (FG/MGA/E) were further implanted with a twofold (2) and a fourfold (4) compression, created by the stacking of additional layers of the substitute materials. The samples were retrieved at 1, 2, and 12 weeks (10 groups, 3 time points, n = 5 per time point and group, overall, 150 samples). The area fraction of infiltrated fibroblasts and inflammatory cells was evaluated histologically. Due to within-subject comparisons, mixed models were conducted for the primary outcome. The level of significance was set at 5%.ResultsThe area fraction of fibroblasts increased in all groups over time. At 12 weeks, the densely compressed materials FG4 (1.1%), MGA4 (1.7%), and MGA2 (2.5%) obtained lower values as compared to the other groups, ranging between 4.7 (E2) and 6.5% (MG). Statistically significant differences (p ≤ 0.05) were observed between groups FG4 vs MG/FG2/E/E4 as well as between MGA4 vs MG/FG2/E/E4 and E vs MGA2.ConclusionsHigher levels of compression led to delayed tissue integration. The effect of different compression levels was more distinct when compared to the differences between the materials.Clinical relevanceAll biomaterials demonstrated tissue integration and a minimal concomitant inflammatory reaction. Clinically, it might be more favorable to obtain a sufficient flap release or to reduce the material size to improve the tissue integration processes.