Internal Disc Research Articles

Full-scale test of disc cutter rotary cutting in TBM tunnelling: a case study of Mawan granite in Shenzhen, China

Understanding the distribution of cutting force provides a foundation for the design and optimization of cutterhead layout. The simulation of rotary cutting with a large cutting radius remains a challenge for laboratory tests. In this study, taking the driving condition of the Mawan Tunnel located in the Guangdong-Hong Kong-Macao Greater Bay Area as a case study, a full-scale rotary cutting platform with large cutting radius was used to investigate the rock-breaking effects. Rotary cutting with cutting depths of 1–8 mm and cutting radii of 200–1400 mm were carried out on the granite testing platform using a 19-in disc cutter. The normal force, rolling force, and side force during the cutting process were systematically monitored. Moreover, the time–frequency characteristics of the rock breaking process and the effects of cutting depth, cutting radius and stress state on the average and peak loads were investigated. The results show that the average normal force and rolling force increased with increasing cutting depth, while the side force was less affected by cutting depth through the Boltzman model analysis. The average normal force and rolling force were not significantly affected by the cutting radius, but the average side force decreased as a power function with increasing cutting radius, and showed a stable side force when the installation radius exceeded 1000 mm. The dominant frequency of the cutting force was 0–1.2 Hz, exhibiting notable low-frequency characteristics. Additionally, the ratio of peak to average (RPA) with respect to triaxial cutting force demonstrated an increase with the growth of cutting depth, while RPA in terms of side force exhibited a corresponding growth with the increasing cutting radius. In particular, the cutting force characteristics of the cutterhead obtained in this study can inform the layout of disc cutters and real-life TBM operations, thereby avoiding severe overloading of internal disc cutters.

The Strength of Bisymmetric Modes in SDSS-IV/MaNGA Barred Galaxy Kinematics

The Sloan Digital Sky Survey-IV/Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) Survey data provide an unprecedented opportunity to study the internal motions of galaxies and, in particular, represent the largest sample of barred galaxy kinematic maps obtained to date. We present results from Nirvana, our nonaxisymmetric kinematic modeling code built with a physically motivated Bayesian forward modeling approach, which decomposes MaNGA velocity fields into first- and second-order radial and tangential rotational modes in a generalized and minimally supervised fashion. We use Nirvana to produce models and rotation curves for 1263 unique barred MaNGA galaxies and a matched unbarred control sample. We present our modeling approach, tests of its efficacy, and validation against existing visual bar classifications. Nirvana finds elevated noncircular motions in galaxies identified as bars in imaging, and bar position angles that agree well with visual measurements. The Nirvana-MaNGA barred and control samples provide a new opportunity for studying the influence of nonaxisymmetric internal disk kinematics in a large statistical sample.

Ultrasound Elastography in Temporomandibular Disorders: A Narrative Review.

A class of intricate musculoskeletal diseases known as temporomandibular disorders (TMDs) affects the temporomandibular joint (TMJ) and its supporting structures. The majority of individuals will at some point in their lives experience some degree of TMD symptoms, as these diseases are highly prevalent in the general population. TMDs are multifactorial and are attributed to various physical and biopsychosocial factors. The TMD patients typically experience preauricular pain, tenderness of masticatory muscles, and joint sounds, and these in turn affect their quality of life. To carry out the appropriate course of treatment, it is critical to make an accurate and timely diagnosis. The TMDs are classified as myofascial pain, internal disc derangement, and degenerative disorders of TMJ. Myofascial pain, which is identified by palpating the affected muscles of mastication and tenderness, is one of the most common findings. The muscles in this condition become stiff due to the contraction of myofibrils and are known as trigger bands. The diagnosis of trigger bands involving the masticatory muscles commonly involving the masseter muscle in myofascial pain to date is subjective, and palpation is the only tool used for its diagnosis. An objective assessment of the masticatory muscles is desirable for accurate diagnosis and treatment planning. Various tools like electromyography and hardness meters have been for assessing muscle stiffness, but their application in TMJ muscle disorders has not yielded valuable results. A novel diagnostic method called ultrasound elastography evaluates muscle stiffness both qualitatively and quantitatively using an elastogram and the muscular elasticity index. In this paper, we will review the ultrasound elastographic techniques utilized for the diagnosis and management of TMDs.

Dried blood spot sampling coupled with liquid chromatography-tandem mass for simultaneous quantitative analysis of multiple cardiovascular drugs

Dried Blood Spots (DBS) revolutionize therapeutic drug monitoring using LC-MS for the precise quantification of cardiovascular drugs (CDs), enabling personalized treatment adapted to patient-specific pharmacokinetics with minimal invasiveness. This study aims to achieve simultaneous quantification of eight CDs in DBS, overcoming physicochemical challenges. A two-step protein precipitation method was used for simple and precise sample preparation. The drugs were analyzed using LC-MS/MS in ESI positive-ion mode, showing high sensitivity and linearity, with a correlation coefficient (r2) exceeding 0.999, after being separated on a reversed-phase chromatography by gradient elution of DW-acetonitrile containing 0.1 % formic acid + 2 mM ammonium formate. The validation results indicate good selectivity, with no observed matrix effect and carry-over. The intra- and inter-day accuracy and precision were within 6 % for most drugs, except for digoxin and deslanoside at low therapeutic levels where the variation was within 20 %. Stability tests confirmed suitable DBS handling and storage conditions, indicating drug stability for at least 30 days at room temperature. The analysis of whole spot has demonstrated remarkable precision and reliability in all target drugs. The analysis of 3 mm internal diameter discs, punched in and out of DBS, presumed to contain 3 µL of blood, showed acceptable accuracy for most drugs, with less polar drugs like digoxin and deslanoside showing lower accuracy, indicating a need for further correction due to non-uniform drug distribution. Consequently, the developed LC-MS/MS method enables the quantification of multiple CDs in a single DBS analysis, while suggesting the potential for accuracy-based analysis.

Evaluating the Impact of Various Treatment Modalities on the Chewing Efficiency of Anterior Disc Displacements of Temporomandibular Joint Disorder Cases: A Comparative Study.

Internal disc displacement of the temporomandibular joint (TMJ) is identified by an anomaly between the condylar-disc assembly, which, in many cases, may lead to discomfort and malfunction of the chewing function. The study's objective was to assess the effects of four distinct treatment approaches on temporomandibular disorder cases with anterior disc displacements focusing on their chewing efficiency. One hundred participants suffering from reducible TMJ disc displacement were selected for enrollment in the study. Subjects were divided equally into four groups: group I patients were treated with behavioral therapy; group II patients were treated with low-level laser therapy (LLLT); group III patients were treated with anterior repositioning splints; and group IV patients were treated with flat plane splints. Chewing efficiency was assessed utilizing the fractional sieving method and a synthetic food substitute was created using silicon impression material. The statistical analysis encompassed comparisons of chewing efficiency between groups and between baseline and posttreatment within each group, employing analysis of variance (ANOVA) and paired t tests, respectively. Using the paired t test, a significant difference in chewing efficiency values as expressed by the median particle size was observed between the baseline and 6-month values in all groups (P < 0.05), except for group I where no significant change was noted over the 6 months (P > 0.05). The one-way ANOVA test revealed a statistically significant difference among groups following therapies (P ˂ 0.05). The post hoc Tukey test was employed for pairwise comparisons and revealed statistically significant variances in the main values of chewing efficiency among all groups at a 95% confidence level (P ˂ 0.05). The study's results suggest that occlusal splints and LLLT are more effective in improving chewing efficiency than behavioral interventions.

Geometric determinants of the mechanical behavior of image-based finite element models of the intervertebral disc.

The intervertebral disc is an important structure for load transfer through the spine. Its injury and degeneration have been linked to pain and spinal fractures. Disc injury and spine fractures are associated with high stresses; however, these stresses cannot be measured, necessitating the use of finite element (FE) models. These models should include the disc's complex structure, as changes in disc geometry have been linked to altered mechanical behavior. However, image-based models using disc-specific structures have yet to be established. This study describes a multiphasic FE modeling approach for noninvasive estimates of subject-specific intervertebral disc mechanical behavior based on medical imaging. The models (n = 22) were used to study the influence of disc geometry on the predicted global mechanical response (moments and forces), internal local disc stresses, and tractions at the interface between the disc and the bone. Disc geometry was found to have a strong influence on the predicted moments and forces on the disc (R2 = 0.69-0.93), while assumptions regarding the side curvature (bulge) of the disc had only a minor effect. Strong variability in the predicted internal disc stresses and tractions was observed between the models (mean absolute differences of 5.1%-27.7%). Disc height had a systematic influence on the internal disc stresses and tractions at the disc-to-bone interface. The influence of disc geometry on mechanics highlights the importance of disc-specific modeling to estimate disc injury risk, loading on the adjacent vertebral bodies, and the mechanical environment present in disc tissues.

MODELING OF ROUGH ROTARY MILLING OF CRANKSHAFT PINS

The development of the modern automotive industry requires a quick adaptation of new production methods. This is possible thanks to software capable of simulating manufacturing processes. The paper discusses the modeling of the machining operation of a crankshaft’s crankpins for a diesel engine with the use of the planetary milling method. i.e., modeling of milling operation when a disc milling cutter, having its cutting inserts directed inwards, is performing rotary motion, and at the same time, the axis of this milling cutter circulates around the axis of a machined crankpin. For this purpose, a geometrical model of the machining of the crankshaft’s crankpin has been developed. Based on the design documentation of the crankshaft of the 4C90 type diesel engine and the documentation of the Steyr internal disc milling cutter, their CAD models have been developed, and the both models were linked together with suitable kinematic dependencies. In the next step, the crankpin having a length of 25 mm was divided by planes (in quantity lp=21) into 1.25 mm sections. On the main cutting edge of two cutting inserts of the disc milling cutter, points were marked at intersection locations with these planes. Using the Inventor 2016 system, twelve spline curves have been generated for each plane because each plane intersects 12 cutting inserts mounted in cassettes positioned around the circumference of the body of the disc milling cutter. Next, the spline curves were brought to a common coordinate system, rotating them at an angle resulting from the positioning of the cassettes with cutting inserts in the body of the disc milling cutter. Prepared in such a way, spline curves were written in dwg format, which allowed for trimming of the spline curves at the circle with a radius of rcp = 27.90 mm, corresponding to the radius of the crankpin after milling, considering grinding allowance (ø55h6 + 0.80 mm grinding allowance). As a result, it enabled to leave sections of the arcs tangential to the diameter ø55.80 mm and, in such a way, generate the outline of the shape of the crankpin using the REGION command for 21 cross-sections. The outline of the cylindricity of the crankpin was obtained using the strategy of outlines of the roundness, which were generated earlier; this strategy consisted in the collection of 360 points on the circumference of 21 mutually parallel sections cut by planes perpendicular to the axis of the crankpin. To determine the effects of the circular feed rate of the circulating move of the axis of rotation of the internal disc milling cutter on the accuracy of the machining, simulations of the shape of the crankpin were performed for three values of the feedrate: vf = 1200 mm/min; vf = 2100 mm/min and vf = 3000 mm/min. The spline curves with a determined (depending on the duration of the simulation) number of points: 3500, 2100 and 1409 were obtained for each simulation. The calculated cylindricity deviation for the feedrate vf = 1200 mm/min amounted to CYLrck = 0.2272 mm, for the feedrate vf = 2100 mm/min – CYLrck = 0.2406 mm, while for the feedrate vf = 3000 mm/min – CYLrck = 0.2929 mm.

Properties of barred galaxies with the environment

Context. Barred structures are widespread in a considerable fraction of galactic disks, spanning diverse environments and galaxy luminosities. The environment likely exerts a significant influence on bar formation, with tidal interactions leading to the emergence of elongated features resembling bars within galaxy disks. It is plausible that the structural parameters of bars resulting from tidal interactions in high-density galactic environments differ from those that formed through internal disk instabilities in isolated galaxies. To empirically test this scenario, a viable approach is to compare the structural parameters of bars in galaxies situated within distinct environments. Aims. The objective of this study is to study environmental effects on the properties of bars by conducting a comparison between the two key structural parameters of bars, namely strength and radius, in galaxies situated within the Virgo cluster and galaxies of comparable luminosities found in environments characterized by lower galaxy densities. Methods. We have collected data on the bar radius and bar strength for a sample of 36 SB0 and SBa galaxies located within the Virgo cluster. These galaxies exhibit a large range of magnitudes, with values ranging from Mr = −22 to Mr = −17. Additionally, we analyzed a sample of 46 field galaxies with similar morphologies and luminosity ranges. The measurements of bar parameters were conducted by employing Fourier decomposition on the r-band photometric images of the galaxies. Results. The analysis reveals that the bar radius exhibits a correlation with the galaxy luminosity, indicating that larger bars are typically found in more luminous galaxies. When comparing galaxies with fixed luminosities, the field galaxies display larger bar radii compared to those in the Virgo cluster. However, when the bar radius is scaled by the size of the galaxy, the disparity diminishes and the scaled bars in the Virgo cluster and the field exhibit similar sizes. This is because galaxies of similar luminosities tend to be larger in the field environment compared to the cluster and because the bars adapt to the disks in which they live. Regarding the bar strength, no significant differences were observed for bright galaxies (Mr &lt; −19.5) between those located in the Virgo cluster and those in the field. In contrast, faint galaxies (Mr &gt; −19.5) show stronger bars in the field than in the cluster. Conclusions. The findings of this study indicate that the size of galaxies is the parameter that is influenced by the environment, while the bar radius remains independent of the environment when scaled by the galaxy size. The findings of this study indicate that the environment influences the size of galaxies rather than the bar radius, which remains independent of the environment when scaled by the galaxy size. Regarding the bar strength, there is no influence of the environment for bright galaxies. However, bars in faint galaxies are weaker in the cluster environment. This could be explained by an enhancement of disk thickness in dense environments which is more efficient in faint galaxies. These results support the notion that the internal dynamics and intrinsic characteristics of galaxies play a dominant role in the formation and evolution of bars, regardless of the surrounding environment.

An indirect method for measurement of rock dynamic tensile strength and fracture energy using blasting experiments

Many parameters in numerical simulation can be directly measured through experiments, yet specific parameters pose challenges for experimental testing. The quantification of dynamic tensile strength and fracture energy in rocks constitutes an indispensable requirement for accurately predicting crack initiation location and propagation velocity. It is imperative to acknowledge that these two parameters exhibit a profound dependence on the strain rate imposed on the rocks. Hence, it is essential to establish a reliable strategy for accurately measuring these parameters. In this paper, a novel blasting experimental measuring system was used to determine crucial dynamic fracture parameters. A single internal crack circular disc (SICCD) configuration was proposed and applied in the sandstone specimens testing. A series of numerical models were developed using a tensile crack softening failure criterion. The mechanical behavior and fracture mechanism of the rock under blasting were analyzed numerically. The relationships between dynamic tensile strength, fracture energy, crack initiation time, and propagation velocity have been thoroughly assessed. Through the utilization of statistical methods and the rapid drawing method, the dynamic tensile strength and fracture energy of rocks can be predicted with high precision by integrating experimental and numerical methods specifically designed. The combined approach enables a comprehensive understanding of the dynamic behavior of rock under extreme loading conditions. Furthermore, the validity of the predicted dynamic tensile strength can be rigorously verified through meticulous testing and evaluation procedures.

Cervical Column and Cord and Column Responses in Whiplash With Stenosis: A Finite Element Modeling Study.

Spine degeneration is a normal aging process. It may lead to stenotic spines that may have implications for pain and quality of life. The diagnosis is based on clinical symptomatology and imaging. Magnetic resonance images often reveal the nature and degree of stenosis of the spine. Stenosis is concerning to clinicians and patients because of the decreased space in the spinal canal and potential for elevated risk of cord and/or osteoligamentous spinal column injuries. Numerous finite element models of the cervical spine have been developed to study the biomechanics of the osteoligamentous column such as range of motion and vertebral stress; however, spinal cord modeling is often ignored. The objective of this study was to determine the external column and internal cord and disc responses of stenotic spines using finite element modeling. A validated model of the subaxial spinal column was used. The osteoligamentous column was modified to include the spinal cord. Mild, moderate, and severe degrees of stenosis commonly identified in civilian populations were simulated at C5-C6. The column-cord model was subjected to postero-anterior acceleration at T1. The range of motion, disc pressure, and cord stress-strain were obtained at the index and superior and inferior adjacent levels of the stenosis. The external metric representing the segmental motion was insensitive while the intrinsic disc and cord variables were more sensitive, and the index level was more affected by stenosis. These findings may influence surgical planning and patient education in personalized medicine.

Quantifying internal intervertebral disc strains to assess nucleus replacement device designs: a digital volume correlation and ultra-high-resolution MRI study.

Introduction: Nucleus replacement has been proposed as a treatment to restore biomechanics and relieve pain in degenerate intervertebral discs (IVDs). Multiple nucleus replacement devices (NRDs) have been developed, however, none are currently used routinely in clinic. A better understanding of the interactions between NRDs and surrounding tissues may provide insight into the causes of implant failure and provide target properties for future NRD designs. The aim of this study was to non-invasively quantify 3D strains within the IVD through three stages of nucleus replacement surgery: intact, post-nuclectomy, and post-treatment. Methods: Digital volume correlation (DVC) combined with 9.4T MRI was used to measure strains in seven human cadaveric specimens (42 ± 18years) when axially compressed to 1kN. Nucleus material was removed from each specimen creating a cavity that was filled with a hydrogel-based NRD. Results: Nucleus removal led to loss of disc height (12.6 ± 4.4%, p = 0.004) which was restored post-treatment (within 5.3 ± 3.1% of the intact state, p > 0.05). Nuclectomy led to increased circumferential strains in the lateral annulus region compared to the intact state (-4.0 ± 3.4% vs. 1.7 ± 6.0%, p = 0.013), and increased maximum shear strains in the posterior annulus region (14.6 ± 1.7% vs. 19.4 ± 2.6%, p = 0.021). In both cases, the NRD was able to restore these strain values to their intact levels (p ≥ 0.192). Discussion: The ability of the NRD to restore IVD biomechanics and some strain types to intact state levels supports nucleus replacement surgery as a viable treatment option. The DVC-MRI method used in the present study could serve as a useful tool to assess future NRD designs to help improve performance in future clinical trials.

ID: 215917 Epidural Injection of Micronized Amniotic Membrane for Chronic Lower Back Pain: A Case Study

Chronic lower back pain (LBP) is common and often results due to internal disc disruption, degenerative disc disease, and disc herniation. Symptoms can be multitude including back and leg pain or loss of motor function and are often debilitating. Currents treatments are limited and often provide only short-term symptomatic relief. Micronized amniotic membrane (AM) is a relatively new injectable treatment option with anti-inflammatory, anti-scarring, and pro-regenerative properties.

Assessment of a Discogenic Pain Animal Model Induced by Applying Continuous Shear Force to Intervertebral Discs

BACKGROUND: Chronic discogenic pain includes degeneration-driven changes under the mechanical macroenvironment of an internal disc, which leads to the progressive changes of biochemical microenvironment that induce abnormal ingrowth of the nociceptor. The propriety of the animal model reflecting the pathologic natural history has not been assessed. OBJECTIVES: This study investigated the biochemical evidence of chronic discogenic pain by employing a discogenic pain animal model induced by shear force. STUDY DESIGN: Animal study utilizing rats in vivo model of a shear force device. METHODS: Fifteen rats were divided into 3 groups (n = 5/group) according to the period for which sustained dorsoventral shear force was applied (1 week or 2 weeks); the control group received the spinous attachment unit, without a spring. Pain data were collected using von Frey hairs on the hind paws. Growth factor and cytokine abundance was analyzed in the dorsal root ganglion (DRG) and plasma. RESULTS: After the shear force devices were installed, the significant variables were found to markedly increase in the DRG tissues of the 2-week group; however, they were not altered in the 1-week group. Specifically, interleukin (IL)-6, neurogrowth factor (NGF), transforming growth factor (TGF)-alpha, platelet-derived growth factor (PDGF)-beta, and vascular endothelial growth factor (VEGF) were increased. Meanwhile, the plasma levels of tumor necrosis factor-alpha, IL-1beta, IL-5, IL-6, IL-12, and NGF were increased in the 1-week group; whereas, TGF-alpha, PDGF-beta, and VEGF were increased in the 2-week group. LIMITATIONS: The limitations include the general limitations of quadrupedal animals, the poor precision and flexural deformation of shear force devices, inaccuracies regarding the evaluation of histological denaturation, and short intervention and observational periods. CONCLUSIONS: This animal model effectively generated biochemical responses to shear loading with evidence of neurological changes induced without direct macrodamage to the outer annulus fibrosus. Chemical internals were induced by mechanical externals among the contributing factors of chronic discogenic pain. KEY WORDS: Discogenic pain, dorsal root ganglion, intervertebral discs, low back pain, shear force, interleukin, growth factor, animal model

T-piece Traction Removal for Buried Bumper Syndrome

Percutaneous endoscopic gastrostomy (PEG) has become the standard nutrition access with well-established procedural and long-term safety data. Yet, buried bumper syndrome (BBS) remains a major concern and complicates up to 5% of PEGs. Albeit poorly standardized, endoscopic management is possible in most internal disc migrations with variable traction- or dissection-based techniques available. Most advanced BBS stages > Cyrany stage 2 call for incision of hyperplastic tissue overgrowth due to insufficient traction forces for nondissection extraction.[1]

Anatomic zone division and clinical significance of the lumbar sinuvertebral nerves

BACKGROUND CONTEXTDiscogenic low-back pain (DLBP) is one of the primary causes of low back pain (LBP) and is associated with internal disc disruptions and is mainly transmitted by the sinuvertebral nerve (SVN). The lack of a universal understanding of the anatomical characteristics of the SVN has compromised surgical treatment for DLPB. PURPOSEThis study aims to elaborate on the anatomical characteristics of the SVN and to discuss their possible clinical significance. STUDY DESIGNThe SVNs were dissected and immunostained in ten human lumbar specimens. METHODSThe SVNs at the segments from L1–L2 to L5–S1 in ten human cadavers were studied, and the number, origin, course, diameter, anastomotic branches, and branching points of the SVNs were documented. Three longitudinal and five transverse zones were defined in the dorsal coronal plane of the vertebral body and disc. The vertebrae were divided longitudinally as follows: the region between the medial edges of the bilateral pedicles is divided into three equal parts, the middle third is zone I and the lateral third on both sides are zones II; the areas lateral to the medial margin of the pedicle were zones III. The transverse zones were designated as follows: (a)superior margin of the vertebral body to superior margin of the pedicle; (b) between superior and inferior margins of the pedicle; (c) inferior margin of the pedicle to inferior margin of the vertebral body; (d) superior margin of the disc to the midline of the disc; and (e) midline of the disc to the inferior margin of the disc. The distribution characteristics of SVNs in various zones were recorded, and tissue sections were immunostained with anti-NF 200 and anti-PGP 9.5. RESULTSThe SVNs are divided into main trunks and deputy branches, with 109 main trunks and 451 deputy branches identified in the 100 lumbar intervertebral foramens (IVFs). The main trunks of the SVN originate from the spinal nerve and/or the communicating branch, but the deputy branch originating from both roots was not observed. All the main trunks and deputy branches of the SVNs originate from the posterolateral disc (III d and III e). The deputy branches of the SVN primarily innervate the posterolateral aspect of the intervertebral disc (III d 46.78%, III e 36.36%) and the subpedicular vertebral body (III c 16.85%). The main trunk of the SVNs passes primarily through the subpedicular vertebral body (III c 96.33%) and divides into ascending, transverse, and descending branches in the IVF: III c (23/101, 22.77%) or spinal canal: II c (73/101, 72.28%), II d (3/101, 2.97%), II b (2/101, 1.98%). The main trunk possesses extensive innervation, and except for the most medial discs (I d and I e), it almost dominates all other zones of the spinal canal. At the segments from L1–L2 to L5–S1, 39 ipsilateral anastomoses connecting the ascending branch to the main trunk or spinal nerve at the upper level were observed, with one contralateral anastomosis observed at L5. CONCLUSIONThe zone distribution characteristics of SVNs are similar across all levels. Comparatively, the proportion of double-root origin and the number of insertion points of the SVNs increased at the lower level. The three types of anastomosis offer connections between SVNs at the same level and at different levels. The posteromedial disc is innervated by corresponding and subjacent main trunks, with the posterolateral disc mainly innervated by the deputy branch. CLINICAL SIGNIFICANCEDetailed information and zone distribution characteristics of the lumbar SVNs can help improve clinicians' understanding of DLBP and improve the effectiveness of treatments targeting the SVNs.

Orbits of Particles and Photons around Regular Rotating Black Holes and Solitons

We briefly overview the basic properties and generic behavior of circular equatorial particle orbits and light rings around regular rotating compact objects with dark energy interiors, which are described by regular metrics of the Kerr–Schild class and include rotating black holes and self-gravitating spinning solitons replacing naked singularities. These objects have an internal de Sitter vacuum disk and can have two types of dark interiors, depending on the energy conditions. The first type reduces to the de Sitter disk, the second contains a closed de Sitter surface and an S surface with the de Sitter disk as the bridge and an anisotropic phantom fluid in the regions between the S surface and the disk. In regular geometry, the potentials decrease from V(r)→∞ to their minima, which ensures the existence of the innermost stable photon and particle orbits that are essential for processes of energy extraction occurring within the ergoregions, which for the second type of interiors contain the phantom energy. The innermost orbits provide a diagnostic tool for investigation of dark interiors of de Sitter–Kerr objects. They include light rings which confine these objects and ensure the most informative observational signature for rotating black holes presented by their shadows.

Magnetic resonance imaging and fractal analysis findings in temporomandibular joints with disk perforation

This study compared magnetic resonance imaging (MRI) findings and fractal dimension (FD) values in the temporomandibular joints (TMJs) of study patients with disk perforation vs control patients. Of 75 TMJs examined with MRI for characteristics of the disk and condyle, 45 were included in the study group and 30 in the control group. MRI findings and FD values were compared for significance of differences between the groups. The frequency of subclassifications was analyzed for differences between the two forms of disk configuration and grades of effusion. Mean FD values were analyzed for differences among subclassifications of MRI findings and between groups. Examination of MRI variables revealed that the study group had significantly greater frequencies of flattened disks, disk displacement, flattening and combined defects in condylar morphology, and grade 2 effusion (P=.001) Joints with perforated disks had a large percentage of normal disk-condyle relationships (73.3%). Significant differences were discovered between biconcave and flattened disk configuration in the frequencies of internal disk status and condylar morphology. FD values of all patients varied significantly among the subclassifications of disk configuration, internal disk status, and effusion. Mean FD values were significantly lower in the study group with perforated disks (1.07) compared with the control group (1.20, P=.001). MRI variables and FD can be useful in investigating intra-articular TMJ status.

Dynamical mass measurements of two protoplanetary discs

ABSTRACT ALMA observations of line emission from planet forming discs have demonstrated to be an excellent tool to probe the internal disc kinematics, often revealing subtle effects related to important dynamical processes occurring in them, such as turbulence, or the presence of planets, that can be inferred from pressure bumps perturbing the gas motion, or from the detection of the planetary wake. In particular, we have recently shown for the case of the massive disc in Elias 2-27 as how one can use such kind of observations to measure deviations from Keplerianity induced by the disc self-gravity, thus constraining the total disc mass with good accuracy and independently on mass conversion factors between the tracer used and the total mass. Here, we refine our methodology and extend it to two additional sources, GM Aur and IM Lup, for which archival line observations are available for both the 12CO and the 13CO line. For IM Lup, we are able to obtain a consistent disc mass of $M_{\rm disc}=0.1 \, \mathrm{M}_{\odot }$, implying a disc-star mass ratio of 0.1 (consistent with the observed spiral structure in the continuum emission) and a gas/dust ratio of ∼65 (consistent with standard assumptions), with a systematic uncertainty by a factor of ≃ 2 due to the different methods to extract the rotation curve. For GM Aur, the two lines we use provide slightly inconsistent rotation curves that cannot be attributed only to a difference in the height of the emitting layer, nor to a vertical temperature stratification. Our best-fitting disc mass measurement is $M_{\rm disc}=0.26 \, \mathrm{M}_{\odot }$, implying a disc-star mass ratio of ∼0.35 and a gas/dust ratio of ∼130. Given the complex kinematics in the outer disc of GM Aur and its interaction with the infalling cloud, the CO lines might not well trace the rotation curve and our results for this source should then be considered with some caution.

Multifield nested metafilters for wave propagation control

The present work proposes a novel class of multifield nested tunable metadevices that serve as high performance acoustic metafilters. The designed metafilter is characterized by a multiscale, hierarchical structure. At the mesoscale, the metamaterial consists of a sequence of two different periodically alternating layers: a polymeric homogeneous layer, which exhibits a viscoelastic constitutive response, and a microstructured one. The latter is based on the periodic repetition of a multiphase microscale cell that is composed by a stiff elastic external coating, a viscoelastic phase and an internal disk of piezoelectric material shunted by an external electrical circuit having a tunable impedance/admittance This tuning parameter affects the constitutive elastic properties of the piezoelectric phase and, in turn, the overall response of the microscale cell, thereby ultimately enabling to achieve an optimal filtering performance for the metadevice. Due to the periodicity of the multiphase cell at the microscale, a two-scale variational-asymptotic homogenization technique is exploited in the frequency domain in order to obtain the frequency-dependent overall constitutive properties of the microstructured layer. Subsequently, in-plane free wave propagation inside the periodic multilayered metamaterial at the mesoscale is investigated by means of Floquet–Bloch theory, together with the transfer matrix method. By triggering the shunting effect, a stiffening of the piezoelectric phase can be achieved, which is demonstrated to open low frequency band gaps in the metamaterial frequency spectrum. The filtering capability of the metadevice has been assessed as a function of its geometrical features and the tuning parameter, thus paving the way towards the design of sophisticated and topologically optimized acoustic filters.

Analysis of magnetorheological clutch with double cup-shaped gap excited by Halbach array based on finite element method and experiment

This work describes the magnetic analysis of an innovative double cup-shaped gap magnetorheological (MR) clutch featuring with three smart MR gels. Four kinds of Halbach array is used to excite the MR gel. The apparatus is designed by using a magneto/mechanical finite element method model, which is numerical calculated by COMSOL Multiphysics software. After describing the configuration, the transmittable torque in the designed MR clutch is derived based on the Bingham-Plastic field-dependent constitutive model of the MR gel. Considering the viscosity in the model building, such as the shear yield stress, which also various with change of magnetic flux density. The magnetic flux density distribution, the shear yield stress distribution, the dynamic viscosity distribution and the shear stress distribution inside the MR gel are obtained and carefully studied. Furthermore, the chain layer of internal cylindrical part, external cylindrical part, internal disc part and external disc part with lowest shear stress are found to calculate the transmission torque and slip torque. Then, the structure of the prototype is optimized based on multi-physics analysis. Finally, the optimal MR clutch is developed and the magneto-static torque is tested with detail analysis.