Search Results (35,668)

Electronic coupling within InAs/InP quantum dots (QDs) influences carrier lifetime and thus QD laser performance. In this work, vertical electronic coupling between QDs is theoretically investigated based on a structure of five-layer QD stacks. This analysis illustrates that the resonant tunneling, a consequence of coherent coupling between QDs, should be considered for carrier redistribution. The carrier tunneling time of ground states is estimated by studying two structures of uniform and chirped five-layer QD stacks. The impact of resonant tunneling on optical properties of InAs/InP QD Fabery–Perot (FP) lasers, such as threshold current, light power-current temperature dependence, and relative intensity noise, is investigated through a comparison of uniform and chirped QD lasers. It is found that the carrier resonant tunneling leads to an increase in the threshold current, low characteristic temperature, and high relative intensity noise. By using the chirped QD stacks, the optical properties are improved thanks to less resonant tunneling. Full article

Background: Amnestic mild cognitive impairment (aMCI) is considered a transitional state between normal aging and dementia, often without visible abnormalities on standard brain magnetic resonance (MR) images. The aim of the study was to analyze both microstructural and functional brain abnormalities using advanced MR techniques. Methods: The study included 27 patients with aMCI and an age-matched control group (CG) of 25 healthy subjects. All MR studies were performed on a 3T MR scanner (Philips, Ingenia) with a 32-channel head and neck coil using volumetric 3D T1 sequences, followed by a resting-state functional MRI (rs-fMRI) sequence. Volumetric analysis was performed using the Destrieux atlas to assess potential structural differences between groups. Seed-to-voxel functional connectivity analyses were conducted using the bilateral hippocampi and both anterior and posterior divisions of the parahippocampal gyri as seed regions. Results: Compared to healthy controls, reduced cortical thickness was observed in aMCI subjects in the temporal regions, frontal and orbitofrontal areas, limbic areas, parietal and sensorimotor cortices, as well as occipito-temporal regions. Additionally, significantly increased functional connectivity was observed between bilateral medial temporal lobe (MTL) regions and the right thalamus. Conclusions: Cortical thinning in various brain regions along with the increased functional connectivity between the MTL regions and the right thalamus may reflect potential compensatory mechanisms in response to initial subtle degenerative changes, emphasizing the importance of using both functional and structural imaging to detect early changes in aMCI patients. Full article

Fabry–Perot resonator (FPR) sensors are widely implemented in optical and microwave waveguides because their interference fringe spectra enable highly sensitive, stable, and calibration-free measurements. In contrast, despite the extensive use of beams and plates as waveguides in vibration- and ultrasound-based structural health monitoring (SHM), an explicit FPR framework for these mechanical waveguides has not been established. This paper demonstrates that flexural beams can be rigorously treated as FPRs despite their inherently dispersive nature. Through analytical derivation, wave-propagation analysis, and fringe-based group-velocity extraction, we show that flexural-beam resonances arise from multi-reflection interference analogous to Fabry–Perot interference. A closed-form relationship between the frequency-dependent group velocity and the FPR free spectral range (FSR) is established, enabling inverse determination of mechanical or environmental perturbance from the FPR fringe spectrum. By extending FPR-based fringe analysis to dispersive mechanical waveguides, this work introduces a theoretical framework for implementing dispersive mechanical waveguide-based FPR sensors. Full article

Mitral transcatheter edge-to-edge repair (M-TEER) has emerged as a cornerstone in the management of severe mitral regurgitation, serving as a robust, low-risk alternative to conventional mitral valve surgery. Although thromboembolic risk remains a critical clinical challenge, that varies significantly across the clinical continuum, from pre-procedural substrates to post-procedural management. This review highlights the role of atrial cardiomyopathy in creating a prothrombotic milieu even prior to intervention, while during the procedure, device time emerges as a potentially dominant independent predictor of embolic burden, marking the periprocedural window as the period of peak hazard. Furthermore, this article addresses the notable disparity between the near-universal presence of subclinical ischemic lesions on magnetic resonance imaging and the infrequent incidence of overt neurological deficits. As the post-procedural phase is considered, we discuss the shift from standardized antithrombotic protocols to individualized strategies and the potential role of concomitant left atrial appendage occlusion. Ultimately, integrating these stage-specific clinical and procedural determinants with emerging technologies—like digital twins and artificial intelligence—represents a promising frontier for mitigating embolic risks, optimizing procedural planning and patient safety in the evolving landscape of mitral valve interventions. Full article

Brain tumor detection from magnetic resonance imaging (MRI) is fundamental to computer-aided diagnosis, yet automated models must remain robust to heterogeneous imaging conditions. Despite strong recent progress, many deep learning and transformer-based approaches primarily optimize performance accuracy without explicitly improving feature selectivity and spatial localization, and they typically produce deterministic output without uncertainty estimates, which limits reliability. To overcome these limitations, we introduce UA-EffNet-DA, an uncertainty-aware EfficientNet framework that addresses these limitations through three complementary components. First, EfficientNet-B4 serves as an efficient backbone for discriminative feature extraction. Second, lightweight dual attention modules, comprising channel and spatial attention in parallel, are applied to the model to emphasize what and where discriminative features to focus within MRI slices. Third, Monte Carlo dropout is employed during inference to quantify predictive uncertainty and enable confidence-aware decision. Experiments on two public benchmarks demonstrate strong performance, yielding accuracies of 98.73% on the Figshare dataset and 99.23% on the Kaggle dataset. In addition, explainable AI analysis using Gradient-weighted Class Activation Mapping (Grad-CAM) further indicates that the proposed model concentrates on diagnostically relevant tumor regions rather than background structures, supporting transparent decision-making. Ablation studies confirm the complementary contribution of dual attention refinement and uncertainty-aware inference. Overall, the proposed UA-EffNet-DA framework offers an efficient and interpretable approach for brain tumor detection that supports more reliable clinical decision support through uncertainty-aware predictions. Full article

A micro-cavity based on phase-change material is a very important strategy for the realization of tunable absorption and conversion of terahertz waves. In this work, a tunable terahertz metamaterial absorber based on the phase-change material germanium–antimony–tellurium (GST) is demonstrated. The device features a metal–insulator–metal triple-layer structure, where the dynamic switching of absorption characteristics is achieved via thermally controlled GST phase transition. In the amorphous state, the absorber exhibits a single absorption peak at 7.7 THz. Upon crystallization, the absorption switches to dual peaks at 5.1 THz and 8.3 THz, achieving near-perfect absorption in both states. Full-wave electromagnetic simulations and theoretical analysis based on a multiple-reflection interference model indicate that this performance tuning originates from the GST-phase-transition-induced change in the equivalent optical cavity length. This corresponds to a switch between two resonant modes: coupled inner–outer ring resonance and independent outer ring resonance. These results provide a foundation for developing dynamically tunable terahertz devices with promising applications in terahertz communications, imaging, and sensing. Full article

To improve the low sensitivity of electromagnetic acoustic testing (EMAT) to micro-debonding defects in metal–rubber bonded structures, this study proposes a detection framework combining a magnetic-field-enhanced focusing EMAT with entropy-weighted multi-feature fusion imaging. First, a Halbach-type focusing magnet was designed and evaluated through finite element simulations, showing a substantial enhancement of the effective bias magnetic field in the working region. Then, three complementary echo features, namely amplitude (AMP), time-domain integral (TDI), and power spectral density (PSD), were extracted from the acquired resonance signals and integrated using an adaptive entropy-weighted fusion strategy. Comparative and ablation analyses were further conducted to distinguish the respective contributions of probe enhancement and feature fusion, and to compare entropy-weighted fusion with single-feature imaging and equal-weight fusion. The results indicate that the focused probe mainly improves the defect-response strength at the hardware level, whereas feature fusion mainly improves image contrast, background suppression, and segmentation consistency at the image level. Among the compared methods and under the present experimental conditions, entropy-weighted fusion provides the best overall imaging performance. Under the present experimental conditions, the proposed framework enables reliable detection of 5 mm debonding defects in aluminum-alloy–rubber bonded specimens and 10 mm debonding defects in titanium-alloy–rubber bonded specimens. These results suggest that the combined use of magnetic-field focusing and adaptive multi-feature fusion is a promising approach for the detection and quantitative characterization of micro-debonding defects in metal–rubber bonded structures. Full article

Background: Rare appendicular pathologies (RAP) are uncommon clinical entities with important diagnostic and therapeutic implications. These conditions frequently mimic acute appendicitis, yet they may require different operative strategies and, in selected cases, oncological management. Methods: We performed a retrospective cohort study including all patients who underwent surgery with the intention of performing an appendectomy at the First Surgical Clinic, Emergency County University Hospital of Cluj-Napoca, between 2018 and 2021. During this interval, 330 appendectomies were performed. Patients with a histopathological diagnosis of RAP were included. Clinical, imaging, surgical, histopathological, postoperative, and follow-up data were analyzed, with particular attention to the preoperative diagnostic work-up and imaging-based suspicion of rare appendicular pathology. Results: Ten patients (3.03%) were diagnosed with RAP, including low-grade appendiceal mucinous neoplasm (LAMN; n = 5), mucinous cystadenoma (n = 2), appendiceal adenocarcinoma (n = 1), appendicular diverticulum (n = 1), and stump appendicitis (n = 1). Computed tomography was the main diagnostic modality, particularly in patients with atypical presentation or suspicion of complicated or neoplastic appendiceal disease, while magnetic resonance imaging and colonoscopy provided additional information in selected cases. Preoperative suspicion of a rare or neoplastic appendiceal pathology was achieved in 70% of patients. Laparoscopic appendectomy was performed in 6 patients, open appendectomy in 1 patient, open ileocecal resection in 1 patient, open right hemicolectomy in 1 patient, and laparoscopic right hemicolectomy in 1 patient. Histopathological examination confirmed the diagnosis in all cases. Immediate postoperative outcomes were favorable, without perioperative mortality or major complications; during follow-up, the patient with adenocarcinoma required oncological treatment and resection of a local recurrence 1 year after surgery. Conclusions: RAP represent a small but clinically significant subset of appendiceal disease. Structured preoperative imaging, intraoperative recognition of atypical findings, and an individualized surgical strategy are essential for optimal outcomes and appropriate oncological management. Full article

Thermoacoustic power generation holds significant promise for applications such as solar thermal utilization, industrial waste heat recovery, and distributed energy systems, owing to its high efficiency and reliability. Conventional standing-wave and traveling-wave thermoacoustic generators, however, are often limited by bulky resonators and substantial acoustic power dissipation. Replacing the resonator with a linear alternator (LA) offers an effective means to improve system compactness and output performance. Nonetheless, under standing-wave acoustic conditions, the LA’s large piston swept volume increases the device size, thereby constraining overall compactness. To address this limitation, a novel moving-magnet LA with electromagnetic components integrated into the moving piston is proposed. Compared to conventional configurations, this design significantly reduces the size and weight of the alternator. Furthermore, the influence of different magnetic circuit configurations on output performance is systematically investigated, enabling optimization of the alternator design. Results demonstrate that the proposed alternator achieves a more compact structure while delivering output performance comparable to that of conventional external magnetic-circuit designs, thereby validating the feasibility of the proposed approach. Full article

Atypical Parkinsonisms are a diverse group of diseases associated with multiple pathologies, including synucleinopathies and tauopathies. Atypical Parkinsonisms include progressive supranuclear palsy, corticobasal degeneration, multiple system atrophy, and dementia with Lewy bodies. The examination of these diseases is complicated due to their overlapping clinical manifestations. Hence, tools enabling reliable supplementary assessment of atypical Parkinsonisms are needed. The most common methods involve neuroimaging; however, these evaluations generally involve basic magnetic resonance imaging and indicate possible morphological changes. Less attention is given to disease background assessment. Biochemical assessment enables a more detailed examination of the factors impacting neurodegenerative processes. The features that may impact the pathophysiology of these diseases include metabolic abnormalities, excessive inflammation, and environmental factors. In this context, proteomic evaluation, as analyzed in this article, could partly address the insufficiently described aspects of the unclear pathological mechanisms related to atypical Parkinsonisms. Full article

The present study focuses on liquid-precursor-mediated chemical vapor deposition (under ambient pressure and moderate temperature range) of WSe₂ on sapphire using ammonium meta-tungstate and sodium cholate. The investigation provides additional results and information for the WSe₂ cluster formations on sapphire as an extension of our previous study, especially based on structural, chemical and morphological characterization of the observed largest and predominant polygonal WSe₂ domains whose lateral size can reach several hundreds of micrometers. In addition, highly symmetrical shapes were also observed. The Raman spectroscopy and atomic force microscopy identified the formation of both mono- and multilayered WSe₂. Moreover, the Raman spectrum analysis shows a complex peak structure with unusual splitting effects in the second-order modes marking strong activity of excitonic-resonance processes. Full article

Background/Objectives: Alzheimer’s disease (AD) is characterized by amyloid-beta accumulation and neuroinflammation, yet the molecular target of Ginsenoside Rg1 remains elusive. This study aimed to elucidate the neuroprotective mechanism of Ginsenoside Rg1, specifically investigating its interaction with C-C motif chemokine receptor 3 (CCR3). Methods: We utilized 5xFAD transgenic mice and CCR3-overexpressing BV2 microglial cells. Behavioral assessments, enzyme-linked immunosorbent assays, quantitative real-time polymerase chain reaction, molecular docking, and surface plasmon resonance were employed to evaluate cognitive function and molecular pathways. Results: Ginsenoside Rg1 treatment significantly ameliorated spatial learning and memory deficits. Quantitatively, Rg1 reduced cortical amyloid-beta 1–40 levels (p < 0.05) and bound directly to CCR3 with a dissociation constant of 3.599 × 10⁻⁵ mol/L. This inhibition suppressed neuroinflammation and restored neurotrophic factors, including Brain-derived neurotrophic factor. Conclusions: CCR3 is a novel pharmacological target for Ginsenoside Rg1, providing a precise molecular basis for its neuroprotective effects. Future research should focus on clarifying the pharmacokinetic profile and brain bioavailability of Ginsenoside Rg1 to facilitate clinical translation. Full article

Background: Facial asymmetry in patients with dentofacial deformity is often associated with occlusal asymmetry, functional differences in mastication, and temporomandibular joint (TMJ) conditions. However, side-to-side differences in the stability of masticatory movement and their relationship with oral function have not been fully clarified. Therefore, this study aimed to investigate differences in masticatory movement, oral function, and the prevalence of MRI-based structural features of the temporomandibular joint between the deviated and non-deviated sides in patients with facial asymmetry. Methods: Twenty-one patients with dentofacial deformity and facial asymmetry were included in this study. Oral function was evaluated by measuring occlusal contact area, occlusal force, and masticatory performance. Masticatory movement was recorded using a mandibular movement recording system, and parameters related to the masticatory path and chewing speed were calculated. The stability of masticatory movement was evaluated using the variance of these parameters across chewing cycles. Temporomandibular joint structural features were assessed using CT and MRI. Comparisons between the deviated and non-deviated sides were performed using paired statistical tests. Results: Occlusal contact area and occlusal force were significantly greater on the deviated side than on the non-deviated side (p = 0.001 and p = 0.006, respectively), whereas no significant difference was observed in masticatory performance (p = 0.211). The deviated side showed a smaller closing angle (p = 0.005) and maximum lateral amplitude (p = 0.019), indicating a more vertical chewing pattern. The stability of masticatory movement, evaluated using the variance of masticatory path and velocity parameters, was significantly greater on the deviated side (e.g., variance of cycle axis angle, p = 0.002; variance of maximum closing velocity, p = 0.006). In addition, the prevalence of imaging-based structural features of the temporomandibular joint was significantly higher on the deviated side (p = 0.016). Conclusions: Patients with dentofacial deformity and facial asymmetry were associated with functional asymmetry between the deviated and non-deviated sides. The deviated side showed greater occlusal contact area, occlusal force, and stability of masticatory movement. These findings suggest that the deviated side may be functionally favorable for mastication and may be related to a tendency toward preferential chewing behavior. However, because the habitual chewing side was not directly evaluated in the present study, this interpretation should be considered cautiously and viewed as hypothesis-generating. Full article

In this work, we present a detailed comparison of the SuSAv2 (SuperScaling Approach version 2) and RDWIA (Relativistic Distorted-Wave Impulse Approximation) models with measurements of charged-current neutrino-induced single-pion production from different experiments (T2K, MINERvA and MiniBooNE), studying the differences between the two theoretical descriptions. The neutrino energy range in these experiments spans from hundreds of MeV to roughly 20 GeV, and the nuclear targets are mainly composed of ${}^{12}$C. The SuSAv2 model uses the single-nucleon inelastic structure functions from the ANL-Osaka DCC model, which allows for a separation of pion production channels, distinguishing between the ${\pi }^{+}$, ${\pi }^{-}$ and ${\pi }^0$ final states. In the RDWIA approach, the Hybrid model developed by the Ghent group is used for the description of the boson–pion–nucleon vertex. Full article