Search Results (279)

Background: A high-fat diet has been shown to have an impact on metabolism resulting in changes in arterial wall thickness and degeneration of surviving neural cells of the hippocampus. The present review focuses on the various animal models used to induce high-fat diet conditions for studying obesity-induced atherosclerosis, along with the associated changes observed in surviving neural cells of the hippocampus. It also highlights the limitations of rodent models and discusses their implications for human research. Methods: The sources for the literature search were Scopus, PubMed, Medline and Google Scholar. Both animal and human studies published were considered and are cited. Results: High-fat-diet-induced vascular changes, mainly in the tunica media, has been shown to have more impact on medium-sized arteries and on the Cornu Ammonis three subregions and outer dentatae gyrus of the hippocampus. Conclusions: High-fat-diet-induced neurovascular changes have been studied radically in animal models, and more supporting studies representing preclinical research should be advanced to humans. Full article

Marine ecosystems are characterized by an immense biodiversity and represent a rich source of biological compounds with promising potential for the development of novel therapeutic drugs. This review describes the most promising marine-derived neuroprotective compounds with strong potential for the treatment of neurodegenerative disorders. We focus specifically on the retina and brain—two key components of the central nervous system—as primary targets for therapeutic interventions against neurodegeneration. Alzheimer’s disease and retinal degeneration diseases are used here as a representative model of neurodegenerative disorders, where complex molecular processes such as protein misfolding, oxidative stress, and neuroinflammation drive disease progression. We also examine gene therapy approaches inspired by marine biology, with particular attention to their application in retinal diseases, aimed at preserving or restoring photoreceptor function and vision. Full article

To overcome the limitations of current train positioning systems, including low positioning accuracy and heavy reliance on track transponders or GNSS signals, this paper proposes a novel LiDAR-inertial and visual landmark fusion framework. Firstly, an IMU preintegration factor considering the Earth’s rotation and a LiDAR-inertial odometry factor accounting for degenerate states are constructed to adapt to railway train operating environments. Subsequently, a lightweight network based on YOLO improvement is used for recognizing reflective kilometer posts, while PaddleOCR extracts numerical codes. High-precision vertex coordinates of kilometer posts are obtained by jointly using LiDAR point cloud and an image detection box. Next, a kilometer post factor is constructed, and multi-source information is optimized within a factor graph framework. Finally, onboard experiments conducted on real railway vehicles demonstrate high-precision landmark detection at 35 FPS with 94.8% average precision. The proposed method delivers robust positioning within 5 m RMSE accuracy for high-speed, long-distance train travel, establishing a novel framework for intelligent railway development. Full article

This paper proposes relaxed Simultaneous Signal and Noise Matching (SSNM) conditions to address limitations in selecting source degeneration inductors for multistage LNA design, achieved by introducing controlled mismatches at the external ports. Additionally, a novel frequency-bounded mismatch envelope is introduced to guide load termination selection based on desired IM-OM (input mismatch-output mismatch) characteristics across the operating band. Building on these concepts, a systematic, easy-to-follow strategy is presented for implementing wideband multistage low-noise amplifiers (LNAs), significantly reducing reliance on blind CAD-based optimisation. This approach is validated through a three-stage MMIC LNA prototype, fabricated using a 0.15 μm GaAs process and operating from 28 to 34 GHz. The measured results closely match the simulation, demonstrating a stable gain of 23 ± 1 dB and a noise figure of 2–2.5 dB, confirming the practical effectiveness of the proposed design approach for wideband amplifiers. Full article

Ocular diseases can significantly affect vision and overall quality of life, with diagnosis often being time-consuming and dependent on expert interpretation. While previous computer-aided diagnostic systems have focused primarily on medical imaging, this paper proposes VisionTrack, a multi-modal AI system for predicting multiple retinal diseases, including Diabetic Retinopathy (DR), Age-related Macular Degeneration (AMD), Diabetic Macular Edema (DME), drusen, Central Serous Retinopathy (CSR), and Macular Hole (MH), as well as normal cases. The proposed framework integrates a Convolutional Neural Network (CNN) for image-based feature extraction, a Graph Neural Network (GNN) to model complex relationships among clinical risk factors, and a Large Language Model (LLM) to process patient medical reports. By leveraging diverse data sources, VisionTrack improves prediction accuracy and offers a more comprehensive assessment of retinal health. Experimental results demonstrate the effectiveness of this hybrid system, highlighting its potential for early detection, risk assessment, and personalized ophthalmic care. Experiments were conducted using two publicly available datasets, RetinalOCT and RFMID, which provide diverse retinal imaging modalities: OCT images and fundus images, respectively. The proposed multi-modal AI system demonstrated strong performance in multi-label disease prediction. On the RetinalOCT dataset, the model achieved an accuracy of 0.980, F1-score of 0.979, recall of 0.978, and precision of 0.979. Similarly, on the RFMID dataset, it reached an accuracy of 0.989, F1-score of 0.881, recall of 0.866, and precision of 0.897. These results confirm the robustness, reliability, and generalization capability of the proposed approach across different imaging modalities. Full article

This paper presents a 17–38 GHz wideband low-noise amplifier (LNA) designed in a 150-nm GaAs pHEMT process. The proposed amplifier adopts a cascode topology with an interstage inductor between the common-source (CS) and common-gate (CG) stages, and a series inductor at the source node of the CS stage for source degeneration. By incorporating these inductors in the amplification stage, simultaneous noise and input matching is facilitated, while achieving flat gain characteristics over a broad frequency range and ensuring stability. In addition, the amplification stage with inductors achieves input matching using only a shunt component in the DC bias path, without any series matching elements. This approach allows the amplifier to achieve simultaneous noise and input matching (SNIM), ensuring low-noise performance over a wide bandwidth. The simulation results show a flat gain of 20–23 dB and a low noise figure of 1.1–2.1 dB over the 17–38 GHz band. Full article

Saccharomyces cerevisiae often undergoes strain degeneration during industrial serial subculturing, though this phenomenon remains understudied. This study first conducted strain screening and biological characterization through TTC (2,3,5-triphenyltetrazolium chloride) colorimetric assays, Durham tube fermentation gas production tests, and WL medium (Wallerstein Laboratory medium) cultivation. Subsequently, the changes in intergenerational biological traits after serial subculturing were investigated. Finally, transcriptomic analysis was employed to examine differential gene expression under high-glucose stress during continuous subculturing. The experimental results demonstrated that: (1) The S. cerevisiae QDSK310-Z-07 (GenBank: PP663884), isolated from farm soil, exhibited robust growth within a temperature range of 24–36 °C, with optimal growth observed at 28 °C. It thrived in a pH range of 4–5.5 and efficiently utilized various carbon and nitrogen sources; (2) After serial subculturing, the strain’s ethanol production capacity and fermentation rate partially declined and then stabilized, while maintaining strong tolerance to high ethanol concentrations and hyperosmotic stress; (3) Transcriptomic analysis revealed significant differential expression of genes related to lipid metabolism, amino acid metabolism, and other pathways under high-glucose stress following continuous subculturing. These findings elucidate the biological trait variations in S. cerevisiae during serial subculturing and provide key metabolic regulation candidate targets for its long-term adaptive evolution under high-glucose stress. Full article

Background: Kölliker’s organ (KO), a transient structure in the cochlea, plays a critical role in the auditory maturation of mammals, particularly during embryonic and early postnatal development. This organ is essential for the proper differentiation and function of cochlear cells, acting as a pivotal source of signalling molecules that influence hair cell development and synaptic connectivity. Methods: This study systematically analyses the literature according to the PRISMA statement in order to evaluate the function roles of KO during cochlea development, reporting the molecular mechanisms and signalling pathways involved. Results: From our study, it emerged that KO supporting cells release adenosine triphosphate (ATP) through connexin hemichannels, initiating a cascade of intracellular calcium (Ca²⁺) signalling in adjacent inner hair cells (IHCs). This signalling promotes the release of glutamate, facilitating synaptic excitation of afferent nerve fibres and enhancing auditory neuron maturation prior to the onset of hearing. Additionally, the spontaneous electrical activity generated within KO supports the establishment of essential neural connections in the auditory pathway. The dynamic interplay between ATP release, Ca²⁺ signalling, and morphological changes in KO is crucial for cochlear compartmentalisation and fluid regulation, contributing to the formation of endolymph and perilymph. Furthermore, KO supports cellular plasticity and may provide a reservoir of precursor cells capable of trans-differentiating into hair cells under specific conditions. Conclusions: Dysregulation of KO function or delayed degeneration of its supporting cells has been implicated in auditory disorders, underscoring the importance of this organ in normal cochlear development and auditory function. Despite its identification over a century ago, further investigation is necessary to elucidate the molecular mechanisms underlying KO’s contributions to auditory maturation, particularly in human physiology. Full article

Background: Intervertebral disc degeneration (IVDD) is caused by an imbalance between the catabolic and anabolic processes within intervertebral disc tissue. Several studies have suggested a potential association between cerebrospinal fluid metabolites (CFMs) and the development of IVDD. However, the existing evidence on the relationship between CFM and IVDD is limited and inconsistent. Methods: The data on 338 cerebrospinal fluid metabolites and intervertebral disc degeneration analyzed in this study were sourced from their respective genome-wide association studies (GWAS). MR analysis employed single nucleotide polymorphisms (SNPs) closely associated with disease as instrumental variables (IVs). The inverse variance weighted (IVW) method was employed as the primary statistical approach, complemented by MR-Egger, the Weighted median, Simple mode, and the Weighted mode for result validation. Comprehensive sensitivity analyses were performed to confirm the robustness of the results and assess for heterogeneity and horizontal pleiotropy. Results: Using the IVW method, this study revealed positive causal effects between 11 cerebrospinal fluid metabolites (CFMs) and intervertebral disc degeneration (IVDD), indicating that elevated levels of these 11 CFMs increase the risk of IVDD. Conversely, negative causal effects were identified for 6 CFMs, suggesting that higher levels of these CFMs have a protective effect against IVDD. Reverse MR analysis indicated 1 positive and 18 negative causal relationships between IVDD and CFMs. Conclusions: Our bidirectional Mendelian analysis provides compelling evidence of a causal relationship between CFMs and IVDD. These findings enhance our understanding of IVDD pathogenesis and highlight the potential for preventive therapies targeting CFMs. Further research is needed to clarify the mechanisms of these CFMs on IVDD. Full article

This work presents a novel three-stage low-noise amplifier (LNA) design methodology. The first two stages consist of common-source stages with inductive source degeneration, while the third stage consists of an RC network attached before the common-source FET transistor. The input matching network is designed to meet the optimum noise measurement termination, which results in a noise Figure of less than 1.6 dB. The highest gain level of 25 dB was measured, and the input and output reflection coefficients are better than 10 dB for the operating bandwidth, i.e., 13–15 GHz. The LNA’s large signal performance and robustness against continuous high input power and pulse waves are reported. This LNA can handle up to 15 dBm input pulse of 50 nS width and 10% duty cycle, and 18 dBm continuous wave without noticing an increment in the forward gate current. Full article

The degenerate optical parametric oscillator (OPO) is demonstrated to generate high-power, broadband mid-infrared MgO-doped periodically poled lithium niobate (MgO:PPLN) femtosecond laser at 151 MHz, synchronously pumped by a commercial Kerr-lens mode-locked Yb:KGW oscillator at 1028 nm. The average power of the degenerate OPO centered at 2056 nm is as high as 740 mW, which is the highest output power from a reported 2 μm degenerate femtosecond OPO, pumped by a bulk solid-state laser. The full width at half maximum (FWHM) spectral bandwidth of the degenerate OPO is 87.4 nm, corresponding to a theoretical, Fourier-limited pulse duration of 51 fs. These remarkable results indicate that degenerate OPO is a great potential candidate technology for generating high-power and few-cycle femtosecond pulses around 2 μm. Such mid-infrared sources are well-suited for high harmonic generation, a pumping source for mid- to far-infrared OPO. Full article

This work investigates the inverse problem of identifying a time-dependent source term in a time-fractional semi-linear degenerate parabolic equation using integral measurement data. We establish the unique solvability of the inverse problem within a suitable functional framework. The proof methodology is based on the Rothe method, where the variational formulation is discretized in time, and a priori estimates for discrete solutions are derived. These estimates are then utilized to demonstrate the convergence of Rothe approximations to a unique weak solution. Additionally, we develop a numerical scheme based on the $L^1$-Galerkin finite element method, combined with iterative refinement, to reconstruct the unknown source term. The numerical performance of the proposed method is validated through a series of computational experiments, demonstrating its stability and robustness against noisy data. Full article

Low back pain is a widespread condition that significantly impacts quality of life, with intervertebral disc degeneration (IDD) being a major contributing factor. However, the underlying mechanisms of IDD remain poorly understood, necessitating further investigation. Environmental risk factors, such as mechanical stress and cigarette smoke, elevate reactive oxygen species levels from both endogenous and exogenous sources, leading to redox imbalance and oxidative stress. The endoplasmic reticulum (ER) and mitochondria, two key organelles responsible for protein folding and energy production, respectively, are particularly vulnerable to oxidative stress. Under oxidative stress conditions, ER stress and mitochondrial dysfunction occur, resulting in unfolded protein response activation, impaired biosynthetic processes, and disruptions in the tricarboxylic acid cycle and electron transport chain, ultimately compromising energy metabolism. Prolonged and excessive ER stress can further trigger apoptosis through ER–mitochondrial crosstalk. Given the unique microenvironment of the intervertebral disc (IVD)—characterized by hypoxia, glucose starvation, and region-specific cellular heterogeneity—the differential effects of environmental stressors on distinct IVD cell populations require further investigation. This review explores the potential mechanisms through which environmental risk factors alter IVD cell activities, contributing to IDD progression, and discusses future therapeutic strategies aimed at mitigating disc degeneration. Full article

The paper considers one of the possible statements of inverse problems in gravimetric and magnetometric remote sensing, proposes a new approach to its solution and formulates algorithms that implement this approach. The problem under consideration consists of finding hypothetical sources of the corresponding potential fields at a given depth based on these fields measured on the Earth’s surface. The problem is reduced to solving systems of linear algebraic equations (SLAE) with ill-conditioned matrices. The proposed approach to the numerical solution is based on improving the condition number of the SLAE’s matrix. A numerical algorithm implementing the proposed approach that is applicable to the stable solution of degenerate and ill-conditioned SLAEs with an approximately given right-hand side is formulated in general form. The algorithm uses the SVD decomposition of the SLAE’s matrix and constructs a new matrix close to the original one with a better (smaller) condition number. An approximate solution to the original SLAE is calculated using the pseudoinverse of the new matrix. The results of a theoretical study of the algorithm are presented and the main properties of the new matrix are given. In particular, the reduction of its condition number is estimated. Several implementations of this algorithm are considered, in particular, the MPMI method, which is based on the use of so-called minimal pseudoinverse matrices. For the model problem, the advantage of the MPMI method over a number of other common methods is shown. The MPMI method is applied to solve the considered problems of gravity exploration and magnetic exploration both in the separate solution of these inverse problems and in their joint solution when processing geophysical data for the Kathu region, in the Northern Cape area of South Africa. Full article

Photic retinopathy is an uncommon clinical entity characterized by retinal damage brought on by excessive exposure to light without protection. It encompasses several distinct clinical categories, including solar maculopathy, handheld laser maculopathy, arc welding maculopathy, and iatrogenic macular degeneration. These clinical entities result from exposure to diverse light sources, such as solar radiation, laser pointers, welding arcs, and operating microscopes during ophthalmic procedures. Patients typically present with bilateral but asymmetric symptoms, including reduced visual acuity, central or paracentral scotomas, photophobia, metamorphopsia, and headaches. After exposure, most people can recover on their own in a matter of weeks to six months without the need for special care. However, thanks to their anti-inflammatory properties, several clinical cases reporting the use of steroids for acute photic retinopathy have been documented in the scientific literature, together with the use of antioxidants. The purpose of this review is to provide an update on this phototoxic maculopathy, describing its different clinical entities, diagnosis, and treatment options, and also focusing on the role of optical coherence tomography for its management. Full article