Search Results (177)

Background/Objectives: Implant placement in transnasal and paranasal regions of the severely atrophic maxilla is challenged by complex anatomy and proximity to critical structures, particularly the nasolacrimal duct (NLD). While cortical anchorage is considered important for implant stability, structured methods for evaluating anatomical eligibility and anatomical risk during planning remain limited. This proof-of-concept study aimed to describe a segmentation-assisted workflow for anatomical assessment of potential paranasal implant trajectories. Methods: A single-case proof-of-concept workflow was developed using CBCT imaging and multi-component anatomical bone segmentation (MCABS). Segmented anatomical structures were used to selectively visualize cortical pathways within the anterior maxilla. Implant planning was performed using axial, non-tilted trajectories. Particular attention was directed toward visualization of the spatial relationship between the planned implant pathway and the nasolacrimal duct. Workflow feasibility was further explored through study-model fabrication, guided implant insertion, and axis-based verification. Results: The proposed workflow enabled selective visualization of cortical structures and facilitated identification of anatomically favorable implant trajectories within the paranasal region. The relationship between the planned implant pathway and the nasolacrimal duct could be directly assessed using the segmented anatomical model. Guided insertion in the study model demonstrated concordance between planned and executed implant axes, supporting the technical feasibility of the workflow. Conclusions: Within the limitations of a single-case proof-of-concept study, the proposed segmentation-assisted workflow may contribute to preoperative anatomical assessment of potential paranasal implant trajectories and their relationship to adjacent anatomical structures. The workflow should be regarded as a methodological demonstration rather than a validated clinical protocol. Further anatomical, reproducibility, biomechanical, and clinical studies are required before broader clinical adoption can be considered. Full article

Hierarchical cloud–edge networks rely on distributed control planes to manage large-scale heterogeneous infrastructures, where controller placement and node assignment strongly affect latency, load balancing, and resilience. Existing methods typically decouple these decisions and provide limited guarantees under controller failures or topology constraints. We introduce a topology-aware joint optimization framework for controller placement and node assignment in hierarchical cloud–edge networks. The problem is formulated as a multi-objective integer linear program capturing latency, load balancing, and control continuity. To ensure scalability, we design a two-phase heuristic: structurally important controller candidates are selected using graph-based metrics, including node degree and k-core decomposition, followed by a redundancy-aware proximity assignment strategy that preserves connectivity under single-controller failures. Experiments on synthetic hierarchical and random topologies with up to 500 nodes show that the proposed approach achieves optimality gaps below 10% with execution times under 10 ms. It improves load distribution and reduces control latency compared to baseline methods while maintaining resilience under controller failures. Results show that exploiting topological structure in joint placement and assignment enables efficient and resilient control plane design for hierarchical cloud–edge networks, supporting near-real-time reconfiguration. Full article

Background: Fractures of the upper cervical spine are challenging to treat due to their proximity to critical neurovascular structures and the need for immediate, stable fixation. Open posterior fixation remains the standard but is associated with soft-tissue disruption and morbidity. Minimally invasive, navigation-assisted pedicle screw fixation represents a viable alternative for older populations, significantly reducing surgical morbidity and tissue trauma. The present study evaluates the accuracy, safety, and perioperative outcomes of minimally invasive navigated posterolateral C1–C2 fixation. Methods: We conducted a retrospective consecutive case review of 51 patients who underwent minimally invasive C1–C2 screw fixation between 2019 and 2024. All procedures were performed using intraoperative O-arm imaging and StealthStation S8 navigation. Screw placement accuracy was assessed using the Bredow modification of the Gertzbein–Robbins and Heary classifications. Perioperative data, including operative time, screw dimensions, radiation dose, complications, and hospital stay, were recorded. Results: Fifty-one patients were included in the study. A total of 212 screws were placed. According to Gertzbein–Robbins grading, 92.4% were Grade A, 6.6% were Grade B, and 1% were Grade C. According to Heary grading, 95% were Grade I and 5% were Grade III. No vertebral artery injuries, new neurological deficits, or intraoperative hardware failures occurred. The mean screw lengths were 33.2 mm (SD = 3.38 mm) (C1) and 32 mm (SD = 4.30 mm) (C2). The mean operative time was 128 min (SD = 52.95 min). The mean radiation dose was 629.16 mGy·cm² (SD = 372.2 mGy·cm²). One superficial wound infection occurred. The median postoperative NRS was 4 (IQR: 4–5). The mean hospital stay was 4.21 (SD = 3.77) days. Conclusions: Our findings demonstrate that the presented approach for C1–C2 fixation is a highly accurate and safe alternative to open posterior fixation for upper cervical fractures. Full article

Background/Objectives: Sacrospinous ligament fixation (SSLF) is a well-established native tissue vaginal procedure for uterine/vault prolapse. Despite favorable success rates, the procedure presents technical challenges due to the deep operative field and proximity to critical neurovascular structures. To review current evidence regarding anatomical considerations, surgical technique, fixation strategies, suture materials, device-assisted methods, and perioperative complications in SSLF. Methods: A structured narrative review of the contemporary literature was conducted, focusing on comparative and systematic studies evaluating unilateral versus bilateral fixation, anterior versus posterior approach, suture type and number, and suture-capturing or anchor-based devices. Anatomical, functional, and safety outcomes were critically analyzed. Results: SSLF achieves favorable anatomical success rates with significant symptom improvement. Meticulous knowledge of sacrospinous ligament anatomy is critical to reduce bleeding and neuropathic complications. Unilateral fixation remains the most common technique, while bilateral fixation may benefit selected patients. According to the available evidence, the anterior approach may better preserve vaginal length, although it may be associated with longer operative time and short-term urinary morbidity. Absorbable and permanent sutures appear to provide comparable anatomical durability, while placement of two sutures remains the most commonly used fixation strategy. Device-assisted techniques may facilitate suture placement but require advanced anatomical expertise. Conclusions: SSLF is a safe and effective suspension procedure when individualized and meticulously performed. Further randomized studies evaluating long-term anatomical and patient-reported outcomes are warranted. Full article

The optimal placement of robotic manipulators within industrial workstations is a critical problem that directly affects task feasibility, accessibility, and operational efficiency. Improper base positioning can lead to joint saturation, reduced manipulability, and limited workspace utilization. This work presents an optimization framework for determining the optimal base placement of robotic manipulators by maximizing a joint-centering performance index based on the κ-index, which quantifies the proximity of joint variables to their allowable limits. The proposed methodology integrates geometric accessibility constraints with a constrained optimization formulation to ensure feasible robot configurations within the workspace. Three optimization strategies—constrained nonlinear programming, gradient projection methods, and genetic algorithms—are evaluated and compared in terms of solution quality and computational performance. Numerical simulations are conducted using a planar 2-DOF manipulator to illustrate the proposed framework and to analyze the influence of workspace geometry on optimal base placement. Additionally, an industrial case study involving the ABB IRB 120 robotic manipulator is presented to assess the practical applicability of the proposed approach. The results demonstrate that the optimization framework improves joint distribution within the allowable limits and enhances robot accessibility across the task workspace. The proposed method provides a practical tool for intelligent workstation design and robotic cell layout optimization in modern industrial environments. Full article

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

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

Shared pilot-scale bases enhance organizational efficiency and improve the success rate of transformation by leveraging spatial proximity among innovation actors, serving as a critical bridge between laboratory R&D and industrialization in biomedicine. Unlike the dominant models in mature markets such as Europe and the United States, which rely on in-house R&D by leading firms or marketized outsourcing, China has developed a government-guided, regionally adapted model of shared pilot-scale bases. This study refines the classification of innovation actors within innovation ecosystem theory and aims to reveal the spatial agglomeration patterns of these actors within shared pilot-based ecosystems and identify the dominant forces within them. Our analysis reveals that: (1) Shared pilot-scale bases anchor themselves in regions of high innovation concentration, representing government-guided agglomerations of diverse innovation actors. (2) Influenced by variations in local economic foundations, innovation resources, and policies, the innovation networks of shared pilot bases in different cities exhibit both functional and morphological similarities and differences. (3) Strategic placement around leading enterprises can rapidly steer regional innovation gradients and foster industrial aggregation through pilot-scale activities. This study can provide a theoretical basis for spatial policymaking in China’s biomedical industry and offer a typological reference for the layout of pilot-scale platforms within heterogeneous innovation ecosystems globally. Full article

This study investigates the stress–strain state of rocks subjected to the impact of penetrators with diverse configurations, employing numerical simulations in the ANSYS Workbench Static Structural module. The research focuses on the interaction between roller cone drill bit teeth and rock formations during blast hole drilling. Through finite element modeling using a linear elastic constitutive model, the influence of penetrator geometry, position relative to borehole walls, angle of attack, and distance to open surfaces on rock fracture parameters is analyzed. Key quantitative findings include: the relative breaking force near the borehole wall reaches 2.8 for soft rocks (siltstones) with a 10 mm tooth diameter, and decreases to approximately 1.0 at a distance of 1.5d from the wall; the optimal angle of attack ranges from 60° to 90° depending on rock hardness; and the proximity to a free surface reduces fracture resistance to as low as 0.23 of the baseline value. Six sets of parabolic regression equations (R² > 0.95) are derived for relative breaking forces across three rock hardness groups and two tooth diameters. Optimal parameters for tooth placement, borehole bottom shapes, and operational conditions are proposed. Implementation of the recommended parameters is estimated to increase drilling efficiency by 10–20% and extend tool service life by 15–30%. The findings provide a scientific foundation for designing advanced roller cone drill bits suitable for rocks with Protodyakonov hardness indices ranging from f = 5 to f = 18. Full article

Background/Objectives: Ureteral complications following oblique lumbar interbody fusion (OLIF) are uncommon and are typically attributed to direct mechanical injury. Functional ureteral obstruction without overt ureteral damage remains poorly characterized. We report two cases that provide clinical and intraoperative evidence of a previously underrecognized mechanism of ureteral obstruction associated with anterior cage positioning during OLIF. Case Presentation: Among 180 OLIF procedures performed by a single surgeon, two cases (1.1%) of postoperative or intraoperative ureteral compromise without direct structural injury were identified. In the first case, postoperative imaging revealed hydronephrosis and focal angulation of the left proximal ureter at the level of the interbody cage, without contrast extravasation. The obstruction was managed with double-J ureteral stenting, and serial renal function monitoring confirmed preserved renal function throughout the clinical course. In the second case, retroperitoneal tissue including the ureter was directly observed intraoperatively to be interposed between the anterior longitudinal ligament and the interbody cage during anterior cage placement. Release of the interposed tissue resulted in immediate ureteral decompression without structural damage. Correlation of the postoperative findings in the first case with the intraoperative observations of the second case supports a unified mechanistic explanation: anterior cage advancement may draw retroperitoneal tissue into the cage–anterior longitudinal ligament interface, subjecting the ureter to focal compression or angulation. Conclusions: Functional ureteral obstruction during OLIF may occur secondary to retroperitoneal tissue interposition rather than direct ureteral trauma. Awareness of this mechanism and meticulous protection of the anterior retroperitoneal layer during cage advancement may help prevent avoidable ureteral complications. Full article

In this work, the design and experimental validation of passive UHF RFID tag antennas are presented with the objective of evaluating the impact of chip placement and miniaturization approaches on tag performance. Four initial antenna layouts were developed by varying the position of the RFID integrated circuit within a coupling loop. The results show that chip placement directly affects the coupling-loop efficiency, the antenna–chip matching condition, and the practical tolerance of the structure to fabrication-related variations. Simulations and measurements identified Antenna 1 as the best-performing reference configuration, exhibiting the most favorable impedance behavior around 866 MHz and a measured power sensitivity of $-16.3$ dBm. Based on this reference design, a miniaturized version (Antenna 5) was obtained by integrating meander lines and capacitive end-loading, reducing the physical size while maintaining resonance at 866 MHz. Both structures were fabricated and evaluated using a Voyantic Tagformance measurement system, with read-range measurements performed under free-space conditions and in proximity to dielectric and conductive materials. The results demonstrate a maximum read range of $8.6$ m for Antenna 1 in free space, while Antenna 5 preserved a read range of $6.3$ m. In the presence of copper, Antenna 1 maintained a read range of 3 m, whereas Antenna 5 achieved approximately $0.5$ m, highlighting the trade-off between miniaturization and robustness under conductive loading. Full article

Aim: Percutaneous liver ablation is a challenging procedure and operator-dependent. During the time when transarterial liver oncological therapies are favored over percutaneous liver ablation, we discuss the challenges of liver ablation with bowel interposition within the needle tract. Materials and Methods: In this IRB-approved retrospective review, we analyzed 481 cases of percutaneous microwave ablation performed between 2012 and 2025 using the NeuWave microwave ablation system with 15 or 20 mm probes under non-contrast CT guidance, with needle trajectories planned based on ultrasound. Dissection techniques were not performed, as intraprocedural ultrasound and CT assessment suggested that the ablation zone would remain confined to hepatic parenchyma. Cases of bowel transgression or close proximity were identified on post-procedural CT imaging, with a follow-up duration of 3 months performed consistently across all cases. Results: Three cases (0.6%) of bowel transgression or close proximity to bowel loops during needle placement were identified. There was no evidence of transmural bowel perforation or clinically significant bowel injury on clinical or radiologic follow-up. Post-procedural imaging demonstrated no free intraperitoneal air or fluid collections. Conclusions: In cases where the ablation zone is confined to hepatic parenchyma, bowel proximity to or inadvertent traversal by the cooled antenna shaft may not result in clinically significant injury and can be managed conservatively in selected patients. Full article

Underwater dynamic target detection, classification, localization, and tracking (DCLT) is central to maritime surveillance and monitoring and increasingly relies on distributed AUV-based robotic sonar networks operating in passive listening and, when required, cooperative multistatic modes. Achieving a robust performance in realistic oceans remains challenging, because sensor placement must adapt to time-varying acoustic conditions and target priors while preserving acoustic communication connectivity, and because frequent reconfiguration under dynamic currents makes classical large-scale planning computationally expensive. This paper presents an integrated deep reinforcement learning (DRL)-based framework for passive-stage sonar placement and dynamic reconfiguration in distributed AUV networks. First, we cast placement as a constructive finite-horizon Markov decision process (MDP) and train a Proximal Policy Optimization (PPO) agent to sequentially build a collision-free layout on a discretized surveillance grid. The terminal reward is formulated to jointly optimize the environment-aware detection performance, computed from BELLHOP-based transmission loss models, and global network connectivity, quantified using algebraic connectivity. Second, to enable time-critical reconfiguration, we estimate flow-aware motion costs for all AUV–destination pairs using a PPO with a Long Short-Term Memory (LSTM) trajectory policy trained for partial observability. The learned policy can be deployed onboard, allowing each AUV to refine its path online using locally sensed currents, improving robustness to ocean-model uncertainty. The resulting cost matrix is solved via an efficient zero-element assignment method to obtain the optimal one-to-one reassignment. In the reported simulation studies, the proposed Sequential PPO placement method achieves a final reward 16–21% higher than Particle Swarm Optimization (PSO) and 2–3.7% higher than the Genetic Algorithm (GA), while the proposed PPO + LSTM planner reduces average travel time by 30.44% compared with A*. The proposed closed-loop architecture supports frequent re-optimization, scalable fleet operation, and a seamless transition to communication-supported cooperative multistatic tracking after detection, enabling efficient, adaptive DCLT in dynamic marine environments. Full article

This study investigates tactile spatial resolution on the palm using two successive rectangular stimuli. Whereas classical tactile resolution studies have focused mainly on point or circular stimulation, less is known about how spatial resolution depends on the placement and geometry of rectangular, device-relevant stimuli. We measured the successive two-stimulus discrimination threshold using three rectangular stimulators across five palm areas aligned along the proximal–distal axis. Participants compared a fixed reference stimulus with a variable comparison stimulus, and the minimum separation at which the two stimuli were perceived as occurring at different locations was recorded as the threshold. The overall average threshold across all experimental conditions was approximately 5.2 mm. The threshold varied systematically across palm regions, being smallest around the palmar digital crease and the base of the fingers. In the central palm, threshold differences were more evident for changes in stimulator width than for changes in stimulator length. These results extend tactile spatial resolution research beyond point stimulation and provide design-relevant guidance for palm-based haptic devices. Full article

The rapid proliferation of mobile devices, particularly smartphones and tablets, has transformed digital entertainment, with mobile gaming emerging as one of the fastest-growing digital segments. Such applications are inherently latency-sensitive and require effective resource management and seamless mobility support. To overcome these issues, this paper suggests a four-layered infrastructure that combines edge, fog, and cloud computing with Software-Defined Networking (SDN) and is assisted by a lightweight proximity-aware heuristic placement strategy and mobility management. The suggested structure follows a microservices contained breakdown of the gaming functionality and uses clustering algorithms to permit coordinated access to resources by edge and fog nodes. A dynamic lightweight proximity-aware virtual machine placement algorithm is presented to deploy application modules nearer to the users depending on the availability and mobility of the resources. The proposed work is simulated using IFogSim2. The proposed model reduces the latency by up to 73 percent and the rate of task completion by 25 percent relative to baseline configurations in the case of dynamic mobility of users. These results indicate that the suggested strategy can be effective in improving the latency-sensitive mobile gaming applications performance in the edge-fog networks. Full article