Search Results (466)

Remote sensing object detection is severely hindered by background clutter and uneven object spatial distribution, limiting the performance of traditional algorithms and the original RT-DETR. To address these issues, this paper proposes an improved RT-DETR-based algorithm, CB-DETR. First, a symmetry-guided Density-Adaptive Attention (DAA) module is designed to tackle insufficient intra-scale feature interaction and poor adaptability to uneven density regions in RT-DETR. Centered on a density estimation network, it predicts target density, generates normalized weights via temperature scaling and softmax, and dynamically adjusts receptive fields through a multi-branch structure to symmetrically adapt to high- and low-density regions, outperforming RT-DETR’s fixed receptive field design. Second, a cross-attention-fused Posterior Dynamic Query Decoder (PDQD) is constructed to overcome fixed query interaction and weak small/occluded object detection in the original decoder. A dynamic query update mechanism optimizes vectors via multi-round iterations, breaking fixed-layer limitations and mining detailed features in complex scenarios, thus improving small/occluded target detection accuracy. Comparative experiments on RSOD, DIOR, and DOTA datasets show that CB-DETR outperforms the original RT-DETR comprehensively: ${\mathrm{mAP}}_{50}$/${\mathrm{mAP}}_{50:95}$ improve by 2.8%/2.1% and Precision (P)/Recall (R) by 4%/2.4% on RSOD; ${\mathrm{mAP}}_{50}$ improves by 1.3% on DIOR and 3% on DOTA. All core metrics surpass the original model and mainstream improved algorithms, verifying the effectiveness and innovation of the proposed improvements. Full article

Background: Oroantral communication (OAC) is a frequent complication after the extraction of maxillary posterior teeth and requires immediate closure to prevent sinus pathology and long-term functional impairment. Objectives: This study aimed to compare the clinical and radiographic outcomes of acute OAC closure using resorbable heterogeneous collagen membranes with those of the conventional buccal advancement flap (Rehrmann method). Methods: Twenty-four patients with OACs diagnosed within 24 h post-extraction were enrolled, and 20 completed follow-up. Patients were allocated to a membrane group treated with a resorbable collagen membrane (Creos Xenoprotect) or a control group treated with a buccal advancement flap. Clinical parameters, including vestibular depth, width of keratinized gingiva, alveolar socket dimensions, postoperative complications, and pain intensity assessed using the Visual Analogue Scale, were evaluated at 1, 7, 14, and 90 days. Radiographic outcomes were assessed using cone-beam computed tomography with linear measurements and normalized bone density analysis in Hounsfield Units at baseline and 90 days. Results: The membrane technique provided significantly better preservation of vestibular depth, keratinized gingiva width, and alveolar socket dimensions, with significantly lower postoperative pain and fewer complications compared with the buccal advancement flap. Higher normalized bone density values were observed in the membrane group, although differences were not statistically significant. Conclusions: Resorbable collagen membranes represent a safe, minimally invasive, and clinically effective alternative to buccal advancement flaps for acute OAC closure. Full article

Low-density cancellous bone results in reduced trabecular support and may increase crestal cortical strain around implants. Osseodensification (OD) compacts trabecular bone and may create a peri-osteotomy densified zone, but its strain-level effects in osteoporotic-like bone are unclear. This study evaluated whether an OD-inspired peri-implant densified trabecular zone reduces crestal cortical strain compared with conventional drilling (CD) in an osteoporotic-like model. A three-dimensional finite element model of a mandibular posterior segment with a 2.0-mm cortical shell and D4 cancellous core was constructed with a 4.3 × 11.4-mm titanium implant and a cemented monolithic zirconia crown. CD used a 4.0-mm osteotomy in D4 bone. The OD model used the same osteotomy plus a concentric peri-implant densified shell with radial density gradation from D1 to D3. The implant–bone interface was defined as bonded. Static 100 N axial and 45° oblique loads were applied. Outcomes were ε_eq, ε_max, and ε_min, summarized as mean top-10 nodal values. OD reduced crestal cortical strains under both loads. Under axial loading, ε_eq, ε_max, and |ε_min| decreased by 17.7%, 19.0%, and 24.1%, respectively. Under oblique loading, the corresponding reductions were 9.8%, 8.0%, and 8.9%. Oblique loading produced higher cortical strains than axial loading in both models. OD-inspired peri-implant densification reduced crestal cortical strain in this osteoporotic-like model, whereas oblique loading remained the main driver of elevated strain. These findings support occlusal/prosthetic strategies that minimize oblique forces and warrant experimental and clinical validation. Full article

Space-based multi-target passive tracking is critical for space situational awareness, but faces severe challenges due to the limited field-of-view (FoV) and directional ambiguity of onboard sensors. These constraints often lead to target loss, poor observability, and decreased estimation accuracy. To address these issues, different fusion architectures have been explored. While centralized measurement-level fusion offers superior accuracy for estimating target states, distributed estimation-level fusion provides greater reliability for estimating the number of targets. To adaptively leverage these two complementary strengths, a dynamic hierarchical fusion method through real-time optimization of the fusion topology is proposed. Specifically, at each decision epoch, sensor nodes are dynamically partitioned into local fusion nodes (LFNs) and detection-only nodes (DONs). Each LFN receives measurements from selected DONs and executes an iterated-correction Gaussian-mixture probability hypothesis density filter. Subsequently, LFNs share and fuse their estimates using the intensity-dependent arithmetic average fusion. This dynamic process is achieved by applying a sensor management scheme based on partially observable Markov decision process (POMDP). To ensure accurate cardinality estimation, the reward function in POMDP utilizes the posterior expected number of targets. The resultant optimization is efficiently solved using a binary particle swarm optimization algorithm. Numerical and hardware-in-the-loop simulations demonstrate the effectiveness of the proposed method in balancing the accuracy of target number and state estimation. Full article

This study explores classical and Bayesian estimation for the two-parameter Chen distribution with randomly censored data, where censoring times follow an independent two-parameter Chen distribution with separate shape and scale parameters. We first derive the maximum likelihood estimators of the unknown parameters, together with their asymptotic variances and credible intervals, and further adopt the method of moments, L-moments and least squares methods for classical estimation. Under the generalized entropy loss function and inverse gamma priors, Bayesian estimation is implemented via Gibbs sampling, with the highest posterior density credible intervals of parameters constructed accordingly. We also investigate the estimation of key reliability and lifetime characteristics of the distribution, and conduct Monte Carlo simulations to compare the performance of all aforementioned estimation methods. Finally, two real-world CMAPSS jet engine lifetime datasets from NASA are applied to validate the practical effectiveness of the proposed estimation approaches, demonstrating the enhanced flexibility of the Chen distribution compared to the exponential distribution in fitting aerospace-related censored data, given the marginal p-values in the K-S tests. Full article

This paper investigates the problem of parameter estimation and reliability analysis for the two-parameter Maxwell distribution under a random censoring mechanism. To address the limitation of the traditional single-parameter Maxwell distribution in practical applications, which lacks the threshold parameter, this paper proposes a two-parameter Maxwell distribution model. By introducing a threshold parameter, this model can more accurately characterize survival data with a minimum life or guaranteed operating time. Specifically, we construct a random censoring data model wherein both the failure time and censoring time are assumed to follow a two-parameter Maxwell distribution. The main research contents include: establishing a randomly censored data model, deriving classical inference methods based on maximum likelihood estimation. Under the general entropy loss function, Bayesian estimation is conducted using conjugate inverse Gamma priors for scale parameters and a uniform prior for the threshold parameter. A hybrid MCMC algorithm is implemented to generate posterior samples and construct highest posterior density credible intervals. We compare their performance through Monte Carlo simulations, evaluating finite-sample behavior in terms of bias, mean squared error, and interval estimation, and finally validating the practicality and superiority of the two-parameter model using real medical datasets from a colon cancer clinical trial. The results demonstrate that the two-parameter Maxwell distribution can more accurately describe survival data with threshold characteristics and outperforms the single-parameter model in terms of model fit and reliability estimation. Full article

Background/Objectives: The popliteus muscle (PM) plays a crucial role in stabilizing the posterolateral aspect of the knee. However, its layered structure and innervation are not well understood due to its location, size, and proximity to neighboring anatomical features. This study aimed to clarify the layered morphology, intramuscular innervation, and fiber-type composition of the PM, providing anatomical insights for clinical interventions. Methods: We examined 32 lower extremities from sixteen formalin-embalmed cadavers using a multimodal approach that included gross dissection, Sihler’s staining, ultrasonography, and histochemical analysis. Results: On average, 2.8 ± 1.1 branches of the tibial nerve entered the PM, with a consistently high-density entry zone located at 56–64% of the muscle length. Sihler’s staining and ultrasonographic analyses revealed a distinct separation between the superficial and deep layers across the central tendon, each exhibiting compartmentalized intramuscular branching territories. The superficial layer was primarily composed of type IIx fibers and exhibited a larger pennation angle, while the deep layer was richer in type IIA fibers with a smaller pennation angle. These findings illustrate that the PM functions as a dual motor unit rather than a uniform structure. Conclusions: The PM exhibits a distinct compartmentalized organization, functioning as a multifunctional motor unit. The identification of specific intramuscular entry zones and the organization of muscle layers provide strong anatomical evidence for improved targeting in neuromuscular-modulating interventions. This enhances the precision, safety, and efficacy of clinical strategies aimed at addressing posterior knee stability and pathologies related to the posterolateral complex (PLC). Full article

Neural progenitor cell (NPC) transplantation is a promising strategy for spinal cord injury repair, as graft-derived neurons can integrate into host circuitry and promote functional recovery. While the brain-regional and dorsoventral identities of NPCs are known to influence graft composition and performance, the importance of axial (rostrocaudal) identity, specifically whether NPCs must be matched to the spinal level of injury, remains poorly understood. To address this, we compared outcomes following transplantation of NPCs isolated from the anterior embryonic spinal cord (A-NPCs) versus the posterior spinal cord (P-NPCs) in a mouse model of C5 cervical dorsal column injury. Following transplantation, NPCs retained their intrinsic molecular axial identities; P-NPC grafts maintained significantly higher expression of the lumbar-associated gene HoxC10 and possessed a higher proportion of Chx10-high V2a neurons compared to A-NPCs. Despite these maintained molecular differences, A-NPC and P-NPC grafts were indistinguishable in neuronal and glial density, axon outgrowth, and their ability to support host axon regeneration, including the corticospinal tract. Long-term behavioral testing and retrograde transsynaptic tracing revealed no significant differences between groups in the recovery of skilled pellet reaching, grip strength, or synaptic integration with host cervical motor circuitry. These findings demonstrate that although transplanted NPCs retain their molecular axial identity in the adult injured environment, this identity is not a primary determinant of anatomical integration or functional outcome. Our findings suggest a degree of plasticity in graft-host interactions and indicate that strict segment-matching is not essential for the efficacy of NPC-based therapies in spinal cord injury. Full article

Dental implantation affects masticatory bite and muscle forces. The temporomandibular joint (TMJ) bears a substantial amount of these masticatory forces. Thus, the objective of the current study was to investigate whether dental implantation alters the human mandibular condyle. Among 556 images, 54 and 22 CBCT scans were successfully identified from 27 patients (10 males and 17 females; 54.93 ± 19.46 years) in the control group and 11 patients (3 males and 8 females; 51.32 ± 13.13 years) in the implant group, respectively. In the control group, CBCT images were obtained longitudinally at the time of implantation and after the post-implantation healing period, both prior to crown placement. In the implant group, CBCT images were obtained at the time of crown placement on a single-tooth implant and after the functional loading period following crown placement. Left and right mandibular condyles were digitally isolated from the images. The bone mineral density (BMD) parameters and morphological changes were assessed using frequency plots of BMD and TMJ osteoarthritis (OA) counts, respectively. In the control group, BMD values were not significantly different between the first and second scans. In contrast, the implant group showed a significant decrease in BMD values, along with a marginal increase in TMJ OA counts after the functional loading period. The TMJ OA counts were highest in the anterior regions, followed by the middle and posterior regions. Most regions showed significantly reduced BMD values, except the antero-lateral and antero-central regions. The current findings give an insight that dental implantation may alter the morphology and BMD of human mandibular condyles. The TMJ OA counts increased, while BMD decreased during the functional loading period of more than 3 months following implantation. Masticatory loading associated with the dental implant likely increases the load on the TMJ, which could stimulate new bone formation to balance the load distribution on the mandibular condyle. Full article

This paper develops simultaneous confidence intervals (SCIs) for pairwise differences of means with zero-inflated Rayleigh (ZIR) distributions, a flexible framework for modeling positively skewed data with excess zeros. Closed-form expressions for the ZIR mean are derived, and several competing interval estimation procedures are investigated, including generalized confidence interval (GCI), parametric bootstrap (PB), method of variance estimates recovery (MOVER), delta-method normal approximation, and highest posterior density (HPD) intervals. The finite-sample performance of the proposed SCIs is examined via extensive Monte Carlo simulations, focusing on empirical coverage probabilities (CPs) and average interval lengths (ALs) over a broad range of parameter configurations and zero-inflation levels. A real data application to road accident fatality counts demonstrates the practical utility of the proposed methodology. The results show that the HPD method consistently achieves the most favorable balance between coverage accuracy and interval efficiency. Overall, this study advances reliable simultaneous inference for zero-inflated models commonly encountered in environmental, biomedical, and reliability studies. Full article

The current study investigated proximal femur bone shape asymmetry and its associations with cartilage composition and functional performance in individuals with hip osteoarthritis (OA). Forty-seven participants with hip OA (mean age: 53.77 ± 12.47 years; 22 females; BMI: 24.49 ± 4.0 kg/m²) were included in this study. Bilateral hip MRI was performed using a 3.0 T MR scanner with 3D proton density fat-saturated CUBE and MAPSS sequences. Automatic segmentation of the proximal femur was achieved using a U-Net framework refined through a human-in-the-loop annotation strategy, followed by three-dimensional bone shape analysis to quantify asymmetry. Cartilage relaxation times were assessed using atlas-based segmentation and quantification, while functional activity was evaluated according to OARSI-recommended criteria. The proposed proximal femur bone segmentation showed a DSC of 96.48% (95%-CI: 96.33–96.64) and Hausdorff Distance of 4.66 mm (95%-CI: 3.80–5.51). Increased bone shape asymmetry in the posterior–lateral–superior region of the proximal femur was associated with functional activity in the chair stand test (rho = −0.41; p = 0.006), and the anterior–lateral–inferior region demonstrated a comparatively higher significant positive correlation ($\mathrm{rho}=0.37$; p = 0.006) with the ${\mathrm{T}}_{1\mathrm{rho}}$values of the acetabular cartilage region. Overall, the findings indicate that region-specific proximal femoral bone shape asymmetry in hip OA is associated with cartilage characteristics and functional impairment, highlighting the potential value of bone shape features as imaging biomarkers relevant to clinical function. Full article

Background: One method for the radiation therapy of rectal cancer is to set patients supine and treat them with volumetric modulated arc therapy (VMAT). The posterior skin dose is of concern due to undesirable bolusing from mounting surfaces the patient lays upon, namely the carbon fiber couch (CFC). The posterior skin dose may be mitigated by positioning the patient on top of a low-density material that separates the patient from the CFC. Purpose: Our objective was to determine the reduction in the posterior surface dose when a mattress or foam board is used to prop the patient away from the CFC. Materials and Methods: Three clinical rectal cancer patient VMAT plans were selected. A solid water phantom with optically stimulated luminescence dosimeters (OSLDs) placed at the posterior surface was mounted using three setups: directly on the CFC, with a mattress on the CFC, and with a 10 cm thick foam board on the CFC. The three VMAT plans were delivered to this phantom, with OSLDs measuring the posterior surface dose with each setup. In the treatment planning system (TPS), the CFC only, mattress, and foam board setups were simulated on the patient’s anatomy with posterior surface doses reported. Results: The OSLD measurements in the phantom showed that the mattress reduced the posterior surface dose on average by 1.3%, and the foam board reduced the dose by 8.3%. The TPS estimates demonstrated that, on average, the mattress reduced the surface dose by 15.8%, and the foam board reduced the dose by 33.0%. It is likely that the TPS had limitations accurately modeling the surface dose, so OSLD measurements were closer to clinical reality. Conclusions: The mattress does not reduce the posterior skin dose enough to warrant its use as a skin sparing device. The CFC produces a bolusing effect that can be reduced by separating the patient from the CFC with a 10 cm thick foam board. Full article

Background: Rehabilitation of the severely atrophic posterior mandible remains surgically challenging, and inferior alveolar nerve (IAN) repositioning is a well-established technique that enables implant placement in anatomically compromised cases. Although neurosensory outcomes following nerve relocation have been extensively investigated, the regenerative capacity of the mandibular canal itself has not been previously evaluated. This study presents the first computer-assisted, cone-beam computed tomography (CBCT)-based assessment of bony canal regeneration after IAN transposition. Methods: Twenty-two patients who underwent unilateral IAN transposition were evaluated using standardized CBCT one year postoperatively. A semi-manual segmentation workflow was performed using Mimics Core Medical software version 27.0 (Materialise), and regenerated canal walls were identified according to four strict criteria: (1) canal continuity across sequential CBCT sections, (2) defined canal walls demonstrating high-density bone (>800 HU, or >400 HU), (3) ≥270° circumferential bony enclosure, and (4) morphology consistent with the native mandibular canal. Regeneration was quantified as the proportion of the surgically disrupted canal segment exhibiting a fully, or near fully, reconstructed canal. Results: Mandibular canal regeneration was observed in all patients. The mean regeneration at one year was 72.7% ± 13% when applying strict >800 HU criteria, with 20 patients demonstrating substantial (>70%) reformation and 2 patients showing partial regeneration (<40%). When a lower density threshold (>400 HU) was applied to include early or less mineralized bone, the mean regeneration increased to 78.1% ± 11%, indicating the presence of maturing bone structures that did not yet meet full-density criteria. Conclusions: Computer-assisted CBCT analysis demonstrates that partial to extensive regeneration of the mandibular canal occurs within one year following IAN transposition. This study provides the first quantitative evidence of this phenomenon, highlighting the intrinsic regenerative potential of the mandibular canal and suggesting a possible association with postoperative neurosensory recovery. Full article

This paper introduces a novel extension of the classical Lindley distribution, termed the X-Lindley model, obtained by a specific mixture of exponential and Lindley distributions, thereby substantially enriching the distributional flexibility. To enhance its inferential scope, a comprehensive reliability analysis is developed under a generalized progressive hybrid censoring scheme, which unifies and extends several traditional censoring mechanisms and allows practitioners to accommodate stringent experimental and cost constraints commonly encountered in reliability and life-testing studies. Within this unified censoring framework, likelihood-based estimation procedures for the model parameters and key reliability characteristics are derived. Fisher information is obtained, enabling the establishment of asymptotic properties of the frequentist estimators, including consistency and normality. A Bayesian inferential paradigm using Markov chain Monte Carlo techniques is proposed by assigning a conjugate gamma prior to the model parameter under the squared error loss, yielding point estimates, highest posterior density credible intervals, and posterior reliability summaries with enhanced interpretability. Extensive Monte Carlo simulations, conducted under a broad range of censoring configurations and assessed using four precision-based performance criteria, demonstrate the stability and efficiency of the proposed estimators. The results reveal low bias, reduced mean squared error, and shorter interval lengths for the XLindley parameter estimates, while maintaining accurate coverage probabilities. The practical relevance of the proposed methodology is further illustrated through two real-life data applications from engineering and physical sciences, where the XLindley model provides a markedly improved fit and more realistic reliability assessment. By integrating an innovative lifetime model with a highly flexible censoring strategy and a dual frequentist–Bayesian inferential framework, this study offers a substantive contribution to modern survival theory. Full article

Background/Objectives: Hemodialysis (HD) is the commonest life sustaining form of kidney replacement therapy in the world; however, this method of treatment have many adverse effects, and even a single HD session affects many organs, including the eyes. The aim of this study was to assess the effect of a single HD session on the ophthalmologic findings in patients with End-stage Renal Disease (ESRD). The second aim of the study was to examine the correlation of these changes with each other and between changes in systemic stressors related to the HD session. Methods: This was a single-center cross-sectional observational study conducted on 32 patients undergoing HD. Selected parameters of the anterior and posterior segment of the eye as well as systemic parameters were assessed before and after a single HD session. Results: Best corrected visual acuity (BCVA) improved, and lens thickness (LT), axial length (AXL), average macular thickness (MT), central MT and total vessel density (VD) of the deep capillary plexus DCP increased significantly after a single HD session. The Schirmer test results, tear break up time (TBUT), anterior chamber depth (ACD), central and average choroidal thickness (CT) decreased significantly after HD. Body weight loss was the only significant systemic change. Decrease in TBUT correlated positively with Schirmer’s test results decrease. Increase in CCT correlated positively with AXL increase. Decrease in central and average CT correlated positively with IOP decrease. Increase in central MT correlated positively with increase in average MT. Decrease in central CT correlated positively with average CT decrease. Change in VD of the SCP correlated positively with change in VD of DCP. Apart from the positive correlation between SBP change and Schirmer’s test results change, there were no correlations between systemic and ophthalmic parameters changes. Conclusions: Our study showed that HD affected the parameters of the anterior and posterior segments of the eye. Numerous correlations between these changes suggest that they are interrelated and represent the complex response of the eye to the HD process. Full article