Search Results (7,036)

Background and Clinical Significance: Osteoblastomas are rare, benign but locally aggressive bone tumors with a predilection for the posterior elements of the spine. Their clinical, radiological and histopathological presentation often overlaps with that of osteoid osteomas, leading to diagnostic and therapeutic challenges—particularly in atypical locations such as the anterior thoracic spine. Case Presentation: We report two cases of young female patients (aged 35 and 30 years) presenting with persistent thoracic back pain unresponsive to NSAIDs. In the first case, imaging revealed a lesion at the right T7 pedicle initially attributed to osteoid osteoma; CT-guided thermoablation was declined due to proximity to neural structures. At this stage, we chose percutaneous transpedicular ablation by drilling through the centrum of the lesion (Nidus) surgically. After this transpedicular resection with initial symptom improvement, the patient developed recurrence with lesion progression into both anterior and posterior columns, requiring a second, open, surgical intervention. In the second case, a lesion at the left T11 pedicle and transverse process was identified directly as osteoblastoma due to size and radiological morphology; initial biopsy was non-diagnostic due to specimen fragmentation. In both cases, histopathology was inconclusive or misleading, while clinical and radiological features—including NSAID unresponsiveness, lesion size, and anatomical extent—favored osteoblastoma. Both patients underwent surgical resection via posterior costotransversectomy, partial hemivertebrectomy, expandable cage placement, and posterior instrumentation (T5–T8 and T10–T12, respectively). The postoperative courses were complicated by thoracic events—hemothorax in the first case and pulmonary embolism in the second—both of which were managed successfully. At follow-up, both patients were neurologically intact and pain-free. Conclusions: These cases emphasize the diagnostic overlap between osteoid osteoma and osteoblastoma and highlight the importance of clinical and radiographic correlation when histopathology is inconclusive. A posterior-only approach with costotransversectomy may be a valid strategy in selected cases of thoracic spinal tumors, although specific complications such as hemothorax must be considered. Full article

Runway microtexture is a key parameter governing pavement friction. In recent years, several microtexture assessment methods have been developed; however, understanding of microtexture evolution under operational conditions, as well as the effects of maintenance techniques, remains limited. In this study, a runway at an Australian airport was investigated using laser profilometry. Measurements were conducted across multiple transverse sections, including aircraft touchdown and mid-runway zones. Microtexture deterioration rates were evaluated based on the estimated number of tire–pavement contacts, and aggregate polishing was assessed at different locations. Measurements were also performed after rubber contamination removal and rejuvenation treatments. The results indicate that approximately 25% of total microtexture reduction can be attributed to surface polishing, with a lower contribution in touchdown zones due to the protective effect of rubber deposits. A non-linear degradation trend was observed in touchdown zones, where approximately 1100 tire contacts reduced average microtexture roughness from 18 μm to 11 μm. Rubber removal effectively restored microtexture close to its original levels across the runway width. A rejuvenation treatment with a covering of fine sand initially improved microtexture; however, rapid deterioration occurred due to loss of the sand coating. These findings improve the understanding of microtexture evolution under operational runway conditions, albeit only at a case study level, and support more effective runway maintenance planning and intervention strategies. Full article

This study investigated how initial ingot thickness (400 mm vs. 520 mm) influences the microstructure and mechanical properties of Al–Zn–Mg–Cu alloys rolled to 80 mm. The combination of smaller initial thickness and lower total reduction (the 400-L route) results in lower dislocation density and a higher fraction of metastable η′ precipitates after T77 treatment. In contrast, the 520-L route, which involves a larger initial ingot thickness coupled with greater rolling reduction, yields higher dislocation density and a greater proportion of stable η phase. Texture also differs: the 400 mm ingot develops a strong S texture and high anisotropy, whereas the 520 mm ingot exhibits Brass texture and reduced anisotropy. Specifically, cross-rolling plus longitudinal rolling of the 520 mm ingot enhances recrystallization texture, giving a short-transverse yield strength of 528 MPa—within 6% of the longitudinal direction. This work offers valuable insights for controlling anisotropy in large 7xxx aluminum plates. Full article

During the operation of a curved stepped spillway, a significant bias flow phenomenon may occur due to centrifugal force, potentially leading to an exposed bed of the inner bank and excessive water depth on the outer bank in severe cases. In order to address the uneven lateral water flow distribution, the transverse slope, where the bottom bed elevation of steps along the outer bank is higher than that along the inner bank, was designed to optimize the hydraulic characteristics of the curved step spillway. Through physical model experiments and three-dimensional numerical simulations, the hydraulic characteristics, including the water surface profiles, flow velocity, pressure on the spillway bed and energy dissipation, were obtained under different discharges and transverse slope angles. The results show that the transverse slope can reduce the bias flow and enhance the uniformity of flow velocity and pressure distribution by balancing centrifugal force. The rational matching of transverse slope angle and discharge is critical for optimizing the hydraulic characteristics of the curved stepped spillway. An appropriate transverse slope angle can effectively alleviate the excessive bias flow phenomenon and ensure uniform distribution of flow velocity, thereby improving the operational stability of the spillway. Full article

Background: Far-Out Syndrome at the lumbosacral junction is caused by extraforaminal compression of the L5 nerve root, frequently involving the lumbosacral ligament (LSL). Conventional piecemeal resection of the LSL may increase the risk of postoperative dysesthesia due to repeated manipulation near the L5 dorsal root ganglion (DRG). This study introduces a novel unilateral biportal endoscopic (UBE) technique for en bloc resection of the LSL. Methods: The technique is based on an osteoclastic release strategy in which the bony attachments of the LSL, including the inferior aspect of the L5 transverse process and the sacral ala, are drilled and released before addressing the ligament itself. This maneuver elevates the LSL away from the underlying L5 DRG and achieves en bloc removal under direct endoscopic visualization. Results: En bloc resection may improve visualization within the narrow extraforaminal corridor and may reduce direct mechanical manipulation of the L5 DRG, which could potentially translate into reduced postoperative dysesthesia. The presented technique enabled effective decompression without repeated instrument insertion beneath the ligament. Conclusions: UBE-assisted en bloc resection of the LSL is a feasible and potentially neuroprotective technique for treating lumbosacral extraforaminal lesions. Full article

External skeletal fixation (ESF) is a versatile method for fracture management in neonatal calves but confers a significant risk of iatrogenic injury to vital structures. The aim of this ex vivo study was to systematically define safe, hazardous, and unsafe corridors for transcortical pin placement in the distal long bones (radius-ulna, tibia, metacarpus, and metatarsus) of Simmental calves to provide precise anatomical guidance. Six fresh Simmental calf cadavers without orthopaedic problems were included in the study. The forearm and hindlimb were disarticulated from the shoulder and hip joints, respectively. The radius-ulna, tibia, and metacarpal and metatarsal bones were dissected transversely from five anatomical levels. Safe, hazardous, and unsafe corridors were determined in each section. No safe corridor was found in the proximal metaphysis and proximal diaphysis of the radius-ulna. Safe corridors were found on the medial side of the radius-ulna, from the mid-diaphysis to the distal metaphysis. The metacarpal and metatarsal bones showed lateral and medial safe corridors. The tibia provided a continuous medial safe corridor. In conclusion, precise topographic mapping is vital for safe ESF. While anatomically safe corridors are the primary choice for ESF, hazardous corridors are viable alternatives if meticulously utilized. By contrast, unsafe corridors must be strictly avoided to prevent severe iatrogenic trauma. Full article

Bessel beams, one of the four known types of beams that are exact solutions of the Helmholtz equation, are remarkable with their non-diffracting nature. In reality, generated with real (Gaussian) laser beams with finite transverse profiles, Bessel-Gaussian beams (BGBs) are quasi-non-diffracting and remarkably stable against spatial perturbations. Quasi-non-diffracting means that the central peaks of the BGBs typically have divergences of the order of microradians. Here, we present experimental evidence that the truncation of the concentric rings surrounding the central peak of the long-range BGBs has a pronounced and controllable effect on the divergence of their peaks. The method is well suited for microradian divergences and has a minimal effect when the divergence of the BGB approaches one milliradian. The truncation of the rings of the BGBs could be applied, for example, in free-space communications, in locating a receiver station with a more divergent beam, after which the spreading of the central peak in space could be reduced to ensure a more secure data transfer. Full article

Background: Prolonged hospitalization after endoscopic endonasal transsphenoidal surgery for non-functioning pituitary adenomas increases costs and complications. Early identification of high-risk patients is crucial for optimizing perioperative management. Methods: In this dual-center retrospective study of 368 patients, a predictive model was developed using a training cohort (n = 268). Prolonged length of stay was defined as ≥75th percentile (≥16 days). LASSO regression selected features from clinical, radiological, and perioperative variables. Independent predictors from multivariable logistic regression were dichotomized via ROC analysis and integrated into a nomogram. Model performance was assessed internally and validated externally (n = 100). Results: Six independent predictors were identified: age > 50 years, vertical tumor diameter > 17.8 mm, anteroposterior diameter > 20.5 mm, transverse diameter > 17.8 mm, anesthesia duration > 194 min, and systolic blood pressure > 119 mmHg. The nomogram showed moderate but reproducible discrimination (AUC = 0.762 in training; 0.750 in validation). Calibration and decision curve analysis confirmed good fit and clinical utility. Conclusion: We developed and validated a practical nomogram predicting prolonged hospitalization risk using readily available perioperative variables. This tool may assist individualized risk stratification and perioperative planning in comparable clinical settings, with potential implications for patient flow and resource utilization. Full article

Objectives: To investigate the possible association between nasal obstruction and maxillary constriction using postero-anterior (PA) cephalograms in nontreated adolescents. Materials and Methods: This retrospective observational study was performed by analyzing the initial PA of 92 subjects in permanent dentition (forty-nine males and forty-three females) who presented without maxillary constriction (control group) and with maxillary transverse deficiency (experimental sample), ages between 12 and 17 years. Patients with any previous orthodontic or surgical treatment of the craniofacial complex were excluded from the study. Linear and angular measurements were taken on PA cephalograms to assess nasal obstruction caused by turbinate hypertrophy and/or the nasal septal deviation. Interval estimation of the prevalence of different variables within gender groups was calculated using the Clopper–Pearson method with a 95% confidence level. The possible associations between maxillary constriction and the presence of nasal anatomical findings were assessed using odds ratios with corresponding 95% confidence intervals. Results: More females than males showed maxillary constriction, but the difference was not significant. Neither the association between maxillary constriction and turbinate hypertrophy nor that with nasal septal deviation reached statistical significance. Conclusions: The hypothesis was rejected. A deviated nasal septum could be slightly associated with a maxillary constriction. However, these results should be taken with caution due to the bi-dimensionality of the measurements on PA. In contrast, three-dimensional evaluations in a wider sample could provide further outcomes to be discussed. Full article

Creating secondary flows that encourage fluid interchange between hot and cold regions is frequently necessary to improve convective heat transfer in compact channels. A well-known passive method for enhancing mixing and boosting thermal performance in laminar regimes is the use of vortex generators (VGs), which create streamwise and transverse vortices. Laminar forced convection in a rectangular channel with rectangular wing vortex generators with triangular tips is investigated numerically in this work. The primary goal is to assess the impact of the number of tips per wing on pressure drop and heat transfer enhancement at a fixed angle of attack (α). This study examines a single row of rectangular wing vortex generators (VGs) with triangular tips and systematically evaluates how variations in tip number influence not only the global Nusselt number and friction factor but also the three-dimensional vortex structure distribution along the channel. This approach contrasts with many previous studies that primarily focus on global performance indices or on classical delta-type VGs. ANSYS Fluent’s finite volume method is used to solve three-dimensional stable, laminar, incompressible flow and heat transfer. Two Reynolds numbers, Re = 456 and Re = 911, are simulated for different triangular-tip configurations at a fixed angle of attack of α = 30°. To connect flow structures to heat transfer behavior, area-averaged Nusselt numbers and friction factors are calculated for each case, and vortex cores and their spatial locations are examined. The findings demonstrate that heat transfer improvement is directly and significantly impacted by the VG tip arrangement. The trade-off between heat gains and pressure losses is highlighted by the fact that some tip configurations produce stronger, more persistent vortices and higher Nusselt numbers at the expense of an increased friction factor. The conclusions are limited to laminar flow conditions at α = 30°, Reynolds numbers of 456 and 911, and the investigated one-, two-, and three-tip configurations. Full article

I analyze the nonlinear Hamiltonian equations of motion for a one-dimensional chain of transverse magnetic nano-islands, seeking solutions for different types of static domain walls (DWs) connecting uniform static states. The system of elongated magnetic islands oriented transverse (y-direction) to the chain direction (x-direction) experiences an applied magnetic field transverse to the chain. The macro-spin model includes dipole interactions between islands, their uniaxial and easy-plane anisotropies, and Oersted energy of the applied field. DWs can form most easily between pairs of degenerate uniform states, described by their local magnetizations as oblique, y-parallel, and y-alternating. The DWs between oblique states are well described with scalar ${\phi }^4$ theory. General DW structures are found via a numerical energy relaxation scheme. At some anisotropy and field parameters, nearest-neighbor dipole interactions drive antiferromagnetic order inside the DW itself. Full article

Bamboo flattening technology provides an efficient approach for improving bamboo utilization, but the heterogeneous stress response and the mechanism of bamboo nodes during the flattening process remain insufficiently understood. In this study, a universal mechanical testing machine equipped with a temperature-controlled chamber was used to simulate the stress state during the flattening process. The effects of different heat treatment temperatures on the transverse mechanical response and chemical properties of different layers of bamboo internodes and nodes were systematically investigated. The results showed that at room temperature, the transverse strength of bamboo exhibited a gradient characteristic of outer layer bamboo (OB) > middle layer bamboo (MB) > inner layer bamboo (IB). Nodes showed higher transverse strength than internodes. As the temperature increased, the transverse properties of all layers significantly declined, with transverse tensile strength showing higher sensitivity. The IB exhibited the poorest thermal stability. Chemical analysis revealed the continuous degradation of cellulose and hemicellulose, while the relative lignin content and relative crystallinity of cellulose increased. This study clarifies the mechanism of heat treatment temperature on the physicochemical characteristics of different parts of bamboo, providing a scientific theoretical basis for temperature control in the industrial production of crack-free flattened bamboo boards. Full article

Reducing cement consumption in mortar systems is essential for lowering the environmental impact of cement-based materials. Conventional mix design approaches rely mainly on particle size distribution and fineness modulus, which do not fully capture the effects of aggregate packing, morphology, and petrographic composition on paste demand and mechanical performance. Fourteen fine aggregates of distinct geological origins were experimentally characterized in terms of physical and petrographic properties. A dataset of 211 mortar mixtures, yielding 633 transverse-strength observations, was used to train a Random Forest Regressor (RFR) model for strength prediction. The model achieved $R^2=0.762$ (RMSE = 0.223 kN; MAE = 0.165 kN), demonstrating its reliability as a surrogate screening tool. This study presents a hybrid framework that integrates particle packing theory with machine learning to optimize fine aggregate blends. By introducing a Paste Demand Index (PDI)—combining normalized uncompacted void content, surface texture, and shape—the framework enables the identification of mixtures that minimize paste demand while maintaining mechanical performance under strength constraints. Results confirm that the proposed PDI and strength-based filtering are robust, offering a physically grounded decision-support methodology for narrowing the design space. Ultimately, this approach provides an efficient strategy for resource optimization, effectively bridging the gap between computational screening and laboratory validation in cement-reduction initiatives driven by the cement-based tile manufacturing industry. Full article

Background: The majority of Class II malocclusions stem from mandibular deficiency, leading to chin retrusion. In growing patients, the ideal correction—aiming for a skeletal mandibular response—should avoid common pitfalls such as “Point B” dropping postero-inferiorly, excessive labial proclination of mandibular incisors, or the lingual tipping and extrusion of maxillary incisors. When planning mandibular advancement (MA) using clear aligners with integrated advancement features, biomechanical forces are not the only consideration; precise management of the lower incisor position is critical for success. Current literature highlights not a good control in digital planning software: these platforms are primarily dentoalveolar-based and lack integrated cephalometric analysis. Consequently, mandibular advancement is often defined by standard linear parameters (typically 2 mm per step), while incisor position is managed through virtual alignment without correlation to cephalometric landmarks like the Pogonion, NB line, or IMPA. The software cannot monitor real-time sagittal or vertical skeletal relationships, the software will elaborate the treatment planning after doctor’s prescription, the clinician must manually adjust incisor positioning based on external cephalometric analysis to prevent dental compensation or excessive proclination. Aim: This clinical case demonstrates a specific arch preparation protocol designed to optimize mandibular advancement in a growing patient with mandibular retrusion. Methods: A 12-year-old female presented with a skeletal and dental Class II malocclusion, characterized by increased overjet and a normal overbite. Treatment was conducted using Invisalign^® clear aligners (22h/day wear, weekly changes). The treatment objectives were: transverse: Correct upper dentoalveolar contraction and coordinate arch form while restoring midline alignment; sagittal: establish Class I molar and canine relationships by correcting the overjet and reducing the labial inclination of the lower incisors; vertical: level the curve of Spee. A key clinical condition of our protocol was the pre-advancement phase: the lower arch was reshaped by reducing the buccolingual inclination (retroclination) and intruding the lower incisors. This was specifically intended to increase the available overjet space, creating the necessary room for subsequent mandibular advancement. Results Treatment was completed in 24 months with high patient compliance. Objectives were successfully met, including the correction of skeletal and dental discrepancies, the establishment of harmonious arch forms, and precise overjet reduction through enhanced control of the mandibular incisors. Conclusions: This case report outlines an optimized clinical strategy for Class II correction. Cephalometric Integration: Perform an initial analysis outside the digital planning software to define the ideal IMPA and NB angles. Anatomic Verification: Utilize radiographic overlays to ensure tooth movement remains within alveolar bone limits. Pre-MA Optimization: Prioritize a “pre-advancement” phase to maximize the sagittal inter-arch space (overjet). A larger overjet allows for a more significant orthopedic effect from the MA features. Stepwise Advancement: Implement mandibular advancement in increments (≥2 mm) with periodic clinical reassessment to facilitate the adaptation of the muscular sling and functional occlusion. Full article

This paper numerically investigates the flow past two circular cylinders of equal diameter arranged in tandem with respect to the incident flow. The upstream cylinder is fixed, and the downstream cylinder is located within the wake interference region for a streamwise center-to-center spacing of L = 5D (D is the cylinder diameter). The downstream cylinder is forced to vibrate transversely in the wake of the upstream cylinder to investigate a regime of wake-induced vibration ($WIV$) at a Reynolds number of $Re=65,000$. The non-dimensional vibration amplitude is fixed at $A/D=0.15$, and the reduced velocity is set to $V_R=5$. The literature has reported that $WIV$ is a phenomenon resulting from the interaction between the incoming wake and the downstream flexible structure, in which the downstream cylinder vibrates significantly over a wide velocity range, and the cross-flow fluid force is not in phase with the body’s motion. The phenomenon of $WIV$ appears combined with a resonant regime, in which the downstream cylinder vibrates at the resonant velocity similar to the vortex-induced vibration ($VIV$) of a single cylinder. The results show that the individual resonant regime is captured for both surfaces without roughness effects. The main contribution of this paper is to demonstrate that the roughness effect variation of the downstream cylinder surface desynchronizes the $WIV$ regime and simultaneously promotes synchronization through the emergence of harmonic frequencies, indicating competition between $VIV$ and $WIV$. Full article