Search Results (46,018)

Ultralight bosonic dark matter (UBDM) that couples to electromagnetism can generate an oscillating magnetic-field signal at the Earth’s surface. This is referred to as the “Earth transducer” effect, as the Earth converts UBDM into a detectable magnetic field. Similar DM-induced fields in laboratory experiments typically scale with the size L of the experiment. Because the Earth transducer signal instead scales with the large radius of the Earth, R, it is one of the most powerful direct probes of UBDM with masses $m_{\mathrm{DM}}\lesssim 1/R\sim 3\times {10}^{-14}\mathrm{eV}$. It has many other favorable properties, such as high spatial and temporal coherence and robustness to atmospheric modeling. In this review, we derive the Earth transducer effect and its properties for multiple UBDM models, and we discuss current and future prospects to detect it. Full article

High-precision, long-endurance navigation remains a central bottleneck for autonomous underwater vehicles (AUVs) operating in GNSS-denied, acoustically constrained, and dynamically disturbed marine environments. This manuscript examines the complete sensing-mapping-estimation chain for underwater geomagnetic navigation. It distinguishes scalar and vector measurements; compares shipborne, towed, and AUV-mounted survey configurations, calibration requirements, platform-interference mitigation, and uncertainty sources; reviews global, regional, and local magnetic models; and evaluates nonlinear map-aided positioning. Existing approaches are organized into map-based matching, filter-aided navigation, geomagnetic simultaneous localization and mapping (SLAM), and matching-area adaptability assessment. Their assumptions, data requirements, uncertainty treatment, accuracy evidence, and computational burden are critically compared. Persistent gaps include magnetic cleanliness, three-dimensional mapping, weak-feature-area observability, benchmark datasets, uncertainty quantification, and reproducible long-duration sea trials. Full article

Permanent magnet synchronous motors (PMSMs) are widely used in new energy vehicles, electric drive systems, and industrial servo applications. Excessive permanent magnet temperature may lead to magnetic performance degradation or even irreversible demagnetization; therefore, accurate estimation of permanent magnet temperature is of considerable importance. However, existing data-driven methods generally rely heavily on high-frequency measurements, and their prediction accuracy tends to deteriorate under low-frequency sampling conditions. Moreover, purely data-driven models lack explicit physical constraints, which limits their interpretability and generalization capability. To address these issues, this study proposes a physics-informed long short-term memory model for permanent magnet temperature prediction. A physics-based loss function is formulated using the PMSM d–q-axis voltage balance equations, while the d- and q-axis inductances are treated as trainable parameters during network optimization. This design enables the temperature prediction task and the electromagnetic constraints to be optimized jointly. Multi-operating-condition experiments are conducted using a publicly available electric motor temperature dataset, and the proposed model is compared with CNN, GRU, MLP-PINN and TNN models. In addition, experiments involving different downsampling ratios, errors in the high-temperature region, parameter sensitivity, physical parameter identification, and input-feature effects are performed to comprehensively evaluate the proposed model. The results show that the PINN-LSTM model achieves the best overall prediction performance, with an MAE of 1.6048 °C, an RMSE of 2.1890 °C, and an R² of 0.9861, outperforming all comparison models. The model also maintains high prediction accuracy in the high-temperature region, with an MAE of 1.363 °C and an RMSE of 1.896 °C. Furthermore, the parameters learned by the model can effectively reconstruct the variation trends of the d- and q-axis voltages under the test operating conditions. Sensitivity analysis of the temperature coefficients further demonstrates that the model is robust to deviations in key physical parameters. These results indicate that the proposed method can achieve accurate and robust permanent magnet temperature prediction under low-frequency sampling conditions, providing an effective solution for motor thermal-state monitoring and health management. Full article

Background/Objectives: Malignant cerebral edema (MCE) is an infrequent but devastating complication of acute ischemic stroke (AIS). Early, reliable identification of patients at risk remains a major clinical challenge. The purpose of this study was to evaluate SCR-U1.8, a single automated imaging biomarker integrating stroke lesion burden and cerebrospinal fluid reserve, for exploratory risk stratification of MCE after AIS. Methods: In this retrospective study, consecutive patients with AIS who underwent diffusion-weighted imaging (DWI) between January 2019 and October 2022 were screened. Stroke lesions were automatically segmented on initial DWI using an ADC threshold of <1.8 × 10⁻³ mm²/s to derive U1.8 lesion volume. Cerebrospinal fluid volume (CSFV) was automatically estimated within the intracranial compartment, and SCR-U1.8 was calculated as U1.8/CSFV. Four low-complexity prediction strategies were evaluated: U1.8 > 82 mL, U1.8 > 145 mL, single-predictor U1.8 logistic regression, and single-predictor SCR-U1.8 logistic regression. Performance was evaluated across 100 repeated stratified patient-level train–test splits. Random undersampling was restricted to the training data, and no synthetic samples were generated. Model performance was assessed by accuracy, sensitivity, specificity, precision, negative predictive value (NPV), F1 score, receiver operating characteristic area under the curve (ROC-AUC), and average precision (AP) as appropriate. Results: A total of 530 patients were included, comprising 198 women and 332 men (mean age, 68 ± 14 years); a total of 12 patients developed MCE. Across 100 repeated stratified train–test splits, SCR-U1.8-LR achieved the highest accuracy (0.990 ± 0.006), precision (0.759 ± 0.150), specificity (0.992 ± 0.005), F1 score (0.806 ± 0.131), ROC-AUC (0.998 ± 0.002), and average precision (0.935 ± 0.062). Compared with the U1.8 > 82 mL threshold, SCR-U1.8-LR achieved significantly higher accuracy, precision, specificity, and F1 score, although sensitivity decreased from 1.000 to 0.900 and NPV decreased slightly from 1.000 to 0.998. Conclusions: SCR-U1.8 may provide a simple and physiologically interpretable measure of stroke lesion burden relative to CSF reserve. The findings remain exploratory because only 12 independent MCE events were available and require external validation. Full article

Low-field nuclear magnetic resonance (NMR) is widely used for nondestructive characterization of petroleum-related porous media, including pore-structure evaluation, fluid identification, relaxation analysis, wettability assessment, and displacement monitoring. Conventional NMR signal models usually rely on the quasi-static approximation, in which the detected magnetic field is assumed to respond instantaneously to Bloch-governed nuclear magnetization. However, classical electrodynamics requires electromagnetic fields generated by time-dependent magnetization sources to depend on the source state at a retarded time. In this study, a retarded magnetic-dipole formulation is developed to evaluate finite-propagation-time effects in low-field NMR signal modeling. The analysis shows that the correction appears mainly as a phase shift governed by the dimensionless parameter $\mathsf{ϵ}={\mathsf{\omega }}_0\mathrm{L}/\mathrm{v}$, where ${\mathsf{\omega }}_0$ is the Larmor angular frequency, $\mathrm{L}$ is the characteristic source–receiver distance, and $\mathrm{v}$ is the effective electromagnetic propagation velocity, with $\mathrm{v}=\mathrm{c}$ in free space. Relaxation-induced amplitude corrections are generally smaller. Numerical examples demonstrate that the quasi-static approximation is well justified when $\mathsf{ϵ}\ll 1$, as typically satisfied in laboratory core NMR. For extended-scale configurations, including unilateral, borehole, underground, and surface NMR, larger propagation paths and medium-dependent electromagnetic properties may increase \epsilon and produce systematic phase deviations. This work provides a theoretical criterion for assessing the validity range of the quasi-static approximation in low-field NMR applications for petroleum-related porous media. Full article

Background/Objectives: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) can produce comparable short-term clinical outcomes, but their regional effects on cervical muscle morphology are incompletely characterized. This study compared 12-month clinical outcomes and quantitative magnetic resonance imaging (MRI) changes after single-level C6–7 ACDF and CDA. Methods: This retrospective longitudinal cohort included 100 age-, sex-, and body mass index-matched patients (50 ACDF and 50 CDA). Neck and arm pain were assessed on 0–10 scales, and the Neck Disability Index (NDI) was analyzed as a 0–50-point score. Regional muscle cross-sectional area (CSA) and fatty infiltration (FI) were quantified on standardized preoperative and 12-month axial T2-weighted turbo spin-echo images at C6–7. The primary analysis included four posterior muscles. CSA change was expressed relative to baseline, whereas FI change was expressed in percentage points. Results: Clinical outcomes were statistically indistinguishable at 12 months (neck-pain score, 0.50 vs. 0.36, p = 0.318; NDI, 2.6 vs. 2.2 points, p = 0.479; perfect-outcome rate, 68.0% in both groups). Both groups showed significant regional posterior muscle CSA reduction and FI increase; however, the magnitude was greater after ACDF than after CDA (CSA reduction, −15% to −19% vs. −5% to −9%; absolute FI increase, +5.1 to +8.2 vs. +1.1 to +2.3 percentage points; all between-group q < 0.001). Surgical technique was independently associated with both MRI change metrics. Greater regional CSA reduction was modestly associated with higher concurrent 12-month neck-pain scores (β = −0.26, p = 0.022). This concurrent association does not establish causation or predict outcomes beyond 12 months. Conclusions: ACDF and CDA produced equivalent measured clinical outcomes at 12 months, while CDA showed a more favorable regional posterior muscle MRI profile. Differential device-related artifact was not quantitatively assessed and cannot be completely excluded, although concordant findings across four implant-remote posterior muscles make artifact unlikely to be the sole explanation. The functional and longer-term clinical significance of this imaging difference is not established and requires prospective longitudinal study. Full article

Hemp hurds (HHs), an underutilised lignocellulosic biomass from agricultural waste, offer potential for bioconversion into high-value bioproducts within a circular bioeconomy. Building on prior work involving magnetic nanoparticle-immobilised cellulase hydrolysis of pretreated HH, this study computationally designed candidate phaCAB expression constructs for cellulolytic hosts toward future PHB production. The objective was to evaluate, in silico, the feasibility of introducing the phaC1, phaA and phaB1 genes from Cupriavidus necator H16 (assembly GCA_000009285.2; loci H16_A1437–H16_A1439) into the cellulolytic hosts Clostridium thermocellum DSM 1313 and Trichoderma reesei RUT C-30. Coding sequences were retrieved and translated individually and host-specific expression compatibility was assessed via codon adaptation index, effective number of codons, GC content and rare-codon frequency/clustering. Host-specific architectures were designed: three independent tef1-promoter cassettes with fungal Kozak contexts and cbh1 terminators for T. reesei (TrePHB3 integration construct), and a single groEL-promoter operon with graded ribosome-binding sites for the pIKM1-based C. thermocellum construct (pCtPHB1); Escherichia coli BL21 (DE3)/pET-24a(+) served only as an intermediate assembly platform. Clustal Omega alignment, virtual plasmid assembly and simulated restriction digestion (SnapGene) confirmed preservation of the open reading frames and expected fragment sizes. ProtParam analysis indicated instability indices below 40 and negative GRAVY values for PhaC, PhaA and PhaB, indicating overall hydrophilic character. This computational framework links HH valorisation, cellulolytic CBP hosts and PHB pathway design within a conceptual biorefinery, supporting future integrated biomass-valorisation platforms; it is computational only and does not demonstrate transformation, expression, PHB accumulation or biomass conversion, which require experimental validation. Full article

Scanning magnetometry based on diamond nitrogen-vacancy (NV) centers enables quantitative magnetic imaging with nanoscale spatial resolution. However, large-area scanning is often limited by geometric distortion arising from the nonlinear hysteresis of piezoelectric positioners, leading to non-uniform pixel spacing and reduced image fidelity. Here, we present a software-based polynomial compensation method that corrects piezoelectric hysteresis without requiring additional hardware or closed-loop position control. By calibrating and analytically inverting the forward and backward hysteresis responses, compensated driving voltages are generated and directly applied during scanning. The method is experimentally validated using a current-carrying patterned gold device and magnetic domains in a hard-disk sample, demonstrating significantly improved geometric accuracy and the removal of scanning artifacts in both topographic and magnetic images. This simple and cost-effective approach provides an effective solution for improving large-area NV scanning magnetometry and other scanning probe imaging techniques based on open-loop piezoelectric positioners. Full article

Background/Objectives: Foreign body ingestion is a frequent gastrointestinal emergency in children. Although most ingested objects pass spontaneously, button batteries, multiple high-powered magnets, sharp objects, and superabsorbent polymers may cause rapid and severe complications. Recent reviews have often focused on individual categories of high-risk objects, whereas practical integration of time-critical diagnosis, comparative guideline recommendations, radiolucent objects, vulnerable pediatric populations, and prognostic risk factors remains limited. This narrative review aims to critically synthesized current evidence and to propose a clinically oriented, risk-stratified framework that distinguishes emergent, urgent, and observational management pathways according to object characteristics, anatomical location, symptoms, elapsed time, imaging findings, and patient-related factors. Methods: A structured narrative review was performed using PubMed/MEDLINE, Scopus and Web of Science. The final searches were performed in July 2026 and covered publications indexed from January 2000 to June 2026. The review included international guidelines, position papers, systematic reviews, meta-analyses and clinically relevant observational studies in patients up to 18 years of age with gastrointestinal foreign body ingestion. Exclusion criteria were studies only involving adults, foreign body aspiration, nasal or auricular insertion, ingestion of caustic substances, duplicate publications, isolated case reports with no broader clinical relevance and articles not available in full text. Evidence was synthesized according to object type, anatomical location, urgency of intervention, imaging strategy, prognostic factors, and patient-related risk. Results: Most ingested foreign bodies pass spontaneously; however, button batteries, multiple magnets, sharp objects, and superabsorbent polymers are associated with distinct mechanisms of injury and a disproportionate risk of severe complications. Time to intervention, object type and size, anatomical location, symptom severity, delayed presentation, and imaging evidence of complications consistently emerge as the principal determinants of outcome. Current international recommendations show broad agreement for immediate removal of esophageal button batteries and sharp objects causing obstruction, but important differences remain regarding gastric batteries, distal magnets, radiolucent objects, and selected asymptomatic patients. Evidence for predictive models is still limited, and most proposed risk factors have not undergone external validation. Vulnerable children (e.g., with neurodevelopmental disorders, pica or recurrent intentional ingestion) require individualized multidisciplinary assessment and follow-up. Conclusions: Pediatric foreign body ingestion should be approached in a time-critical and risk-stratified manner, combining object characteristics, anatomical location, presenting symptoms, time from ingestion, imaging findings, and patient-specific vulnerability. Differentiated triage for emergent intervention, urgent removal and structured observation may improve clinical triage and reduce delays for high-risk cases. Current guidelines offer a robust management framework, but there are significant evidence gaps relating to radiolucent objects, water beads, distal magnets and externally validated predictive models. More multicenter studies are required to support standardized prognostic tools and more consistent decision-making across pediatric emergency settings. Full article

Pilonidal sinus is a chronic inflammatory skin condition predominantly found in the sacrococcygeal region, characterized by recurrent infections and sinus tract formation. Occurrences outside this area, particularly on the anterior chest wall, are exceedingly rare and prone to misdiagnosis. We report a rare case of a 24-year-old Chinese man presenting with a 3-year history of a recurrent, draining lesion on the anterior chest wall. Initial treatment via simple incision and drainage for a presumed sebaceous cyst resulted in delayed wound healing and persistent purulent discharge. Subsequent magnetic resonance imaging (MRI) and computed tomography (CT) revealed a localized superficial lesion. Definitive surgical debridement uncovered a sinus tract containing embedded hair fragments. Histopathological examination confirmed a pilonidal sinus with a robust foreign body giant cell reaction and chronic inflammation. After complete resection, during the nearly two-year follow-up period, the healing has been smooth, and no recurrence has been observed. This case highlights the necessity of detailed clinical history-taking and the inclusion of ectopic pilonidal sinus in the differential diagnosis of refractory chest wall abscesses to prevent repeated, ineffective interventions. Full article

Magnetic field (MF) technologies have been explored in agriculture since the 1930s, with research activity increasing markedly since 2016. However, they have not achieved mainstream adoption, partly because no MF-specific validated methodology exists for evaluating their effects under realistic field conditions. Unmanned Aerial Vehicle (UAV)-based multispectral sensing represents a potential pathway to address this limitation by providing spatially explicit, non-destructive estimates of key canopy physiological variables at field scale, thereby enabling, for the first time, the systematic evaluation and validation of MF treatment responses under open-field conditions. To realise this potential, however, a common evidential basis must first be established by identifying crop physiological variables that are both consistently modulated by MF treatments and reliably detectable by UAV remote sensing. This study addressed this challenge through a dual-stream evidence synthesis of 216 peer-reviewed publications, comprising 102 studies on MF treatments in agricultural crops and 114 studies on UAV-based multispectral monitoring. Evidence from both research domains was synthesised to identify physiological variables that are simultaneously responsive to MF treatments and detectable through UAV remote sensing. Five direct bridge variables were identified: chlorophyll content, nitrogen use efficiency (NUE)/nitrogen assimilation, above-ground biomass (AGB), leaf area index (LAI), and yield. Chlorophyll content emerged as the strongest bridge variable, combining consistent MF responsiveness with UAV estimation accuracies of up to R² = 0.90. Based on these findings, a conceptual framework was developed linking MF treatments, UAV-derived vegetation indices, ground-truth measurements, and machine-learning approaches for field-scale validation. The review revealed a complete absence of integration between the two research domains within the reviewed corpus, despite their strong biological and methodological compatibility. The proposed framework is conceptual and remains to be experimentally validated; it provides the first operational pathway for evaluating MF technologies under realistic farming conditions and may support future research on sustainable and digitally enabled crop production systems. Full article

Symptomatic high-grade carotid stenosis may present with extensive ipsilateral hemispheric hypoperfusion without a large infarct core, a grey-zone phenotype between standard early and truly urgent carotid revascularization. This single-centre retrospective observational study described the procedural and clinical outcomes of urgent carotid revascularization in this imaging-defined subgroup. Consecutive patients treated between June 2015 and August 2025 were included when they had recent ipsilateral anterior-circulation symptoms, ipsilateral internal carotid stenosis > 70%, objective hemispheric hypoperfusion involving at least one third of the anterior circulation territory on CT or MR perfusion, and no intracranial haemorrhage or large established infarction. Twenty-seven patients met the criteria. Median NASCET-style stenosis was 92%, and 14 patients (51.9%) had at least one collateral-limiting feature. Revascularization was performed within 48 h in all cases, by carotid endarterectomy in 25 patients and carotid artery stenting in two. Technical success was 100%. No 30-day death, stroke, intracranial haemorrhage, major adverse event, or target-lesion reintervention occurred. Complete neurological recovery at discharge was observed in 25 patients (92.6%). During median follow-up of 48.6 months, no late ipsilateral stroke, carotid-related neurological event, neurological death, or target-lesion reintervention was recorded. In this small, selected, uncontrolled cohort, urgent carotid revascularization was technically achievable, and no prespecified 30-day safety events were observed. These descriptive findings do not establish comparative safety or clinical benefit and require prospective multicentre validation. Full article

Introduction: Mediastinal lymphangiomas are rare, benign vascular malformations of the lymphatic system that are seldom diagnosed in adults. Due to their varied clinical presentation and heterogeneous imaging characteristics, they pose a significant preoperative diagnostic challenge, frequently mimicking other mediastinal masses. Materials and Methods: We conducted a thorough search of the PubMed/MEDLINE, PubMed Central, and Google Scholar databases. We included articles from 2000 to 2026. Our search yielded 150 articles, out of which we selected 45 articles. Inclusion criteria were strictly limited to adult patients with a solitary mediastinal lymphangioma. Cases involving diffuse systemic lymphangiomatosis, mixed histological features such as lymphangiomyomas or hemangiolymphangioma or studies on pediatric populations were explicitly excluded from the analysis. We also reported a case of mediastinal lymphangioma in a 42-year-old patient, which was surgically resected at the “Marius Nasta” National Institute of Pneumology in Bucharest, Romania. Case Description: An asymptomatic 42-year-old male presenting with exertional chest discomfort following minor trauma demonstrated a lower left hemithorax opacity on chest X-ray. Imagistic studies revealed a 13 × 9 × 6 cm cystic mass in the left supradiaphragmatic costophrenic recess. The patient underwent a complete radical excision. The postoperative recovery was uneventful. Histopathology confirmed a benign cystic mediastinal lymphangioma. Conclusion: Adult mediastinal lymphangiomas are rare entities that require a high index of clinical suspicion. While advanced cross-sectional imaging is invaluable for delineating their characteristics, definitive diagnosis relies on histopathological confirmation. Complete surgical resection, increasingly performed via minimally invasive approaches or standard thoracotomy, remains the therapeutic gold standard, offering an excellent long-term prognosis with virtually no risk of recurrence. For inoperable cases, several non-surgical approaches are available. Full article

Accurate magnetic-field characterization is essential for evaluating wireless power transfer (WPT) systems. Conventional near-field measurements require setup-specific probe calibration, increasing experimental complexity. This paper proposes a calibration-free framework based on a minimal small-loop magnetic-field probe model derived from Faraday’s law, where the voltage-to-magnetic-field conversion coefficient is analytically determined from probe geometry and operating frequency. Its validity is examined by comparing an ideal analytical model, a spatially aware Bessel-function-based model, and full-wave simulations. Full-wave simulations indicate that the loop circumference should remain within approximately $0.1\lambda$ for the modeled probe, while experimental validation at 13.56 MHz supports the method in the tested WPT configuration. Combined with three-axis measurement and augmented-reality (AR) visualization, the method enables practical three-dimensional (3D) magnetic-field mapping. Full article

In single DC-link current sensor-based phase current reconstruction for permanent magnet synchronous motor (PMSM) drives, the current reconstruction dead zone caused by insufficient active voltage vector duration restricted by driver dead time, switching settling, and Analog to Digital Converter (ADC) latency degrades current sensing accuracy, particularly in low modulation and sector boundary regions. Conventional phase shift methods, while extending the sampling window through Pulse Width Modulation (PWM) pattern modification, inevitably introduce asymmetric switching sequences that generate additional phase current harmonics and may reduce the linear modulation range. This article analytically characterizes the dead zone formation mechanism across the space vector plane and proposes a cross-cycle compensation strategy based on vector approximation. The method replaces the reference voltage vector with the nearest measurable vector in the present switching cycle and compensates for the resulting voltage error in the subsequent cycle, thereby extending the sampling window while preserving precise volt-second balance without extra hardware. Experimental results demonstrate that the proposed method eliminates the current reconstruction dead zone, achieves high-fidelity phase current reconstruction, and ensures robust dynamic performance under various load conditions and transients. The feasibility and effectiveness of the single current sensor drive are thoroughly validated. Full article