Search Results (147)

Background: The rapid diffusion of generative Artificial Intelligence (AI) in higher education is reshaping students’ learning practices and raising concerns about unequal access and educational equity. In the Italian university context, where institutional guidelines on AI use are still developing, examining how students adopt and perceive tools such as ChatGPT is particularly relevant. Methods: This quantitative study investigated patterns of ChatGPT use and perceptions among Italian university students, with specific attention to its perceived support for learning and the development of transversal skills. Data were collected through an online survey. Differences across socio-demographic and academic characteristics were analysed using Mann–Whitney and Kruskal–Wallis tests, while associations between ChatGPT use, students’ perceptions, and study-related outcomes were examined using Spearman’s rho coefficients. Results: Students perceived ChatGPT as a useful tool, particularly in supporting the development of analytical, writing, and digital skills. Significant differences emerged across student groups. Higher levels of use and more positive perceptions were reported by freshmen, students studying in urban areas, and those with stronger economic resources. Conclusions: ChatGPT adoption and subjectively perceived institutional support and benefits vary by academic experience and socio-economic background. As the findings are based on self-reported perceptions, they reflect perceived rather than measured learning outcomes, highlighting the need for further research using objective indicators. Full article

The present study investigates the generalized dispersion of a solute in an incompressible MHD flow via a rectangular channel with injectable or suctioned walls. The mathematical model of dispersion suggests a distinct type of mass flux expressed as a fractional partial differential equation based on the time-fractional Caputo derivative. The mass flow in the model under investigation is determined by both the concentration gradient and its historical evolution. A constant external magnetic field is provided transverse to the flow direction. The analysis and discussion of the analytical solution for the advection velocity are performed in relation to the Hartmann number and the suction/injection Reynolds number. To determine the solute concentration in space and time, the unstable fractional convection–diffusion equation is analytically solved. The polynomial in the geographic variable y that has coefficients that depend on the spatial variable x and the time t is the analytical solution of the concentration. The effects of the fractional order of the Caputo derivative, Reynolds number, Hartmann number, and Peclet number on the advection–diffusion process are examined using numerical simulations of the analytical solution of the solute concentration. Full article

Chronic subdural hematoma (CSDH) in frail older adults is increasingly recognized as a sentinel event, with mortality often driven by medical complications rather than neurosurgical factors. We report a failure-to-rescue case in which rapid postoperative deterioration occurred after burr-hole drainage for bilateral CSDH in a frail older adult with diabetes. A clinical picture consistent with sepsis was suspected, and a gastrointestinal source was considered, but the infectious focus could not be confirmed due to limited diagnostic work-up. On admission, chest-computed tomography showed mild right lower-lobe pneumonia, and incidental transverse colonic dilatation was also visible. Burr-hole drainage was uneventful and oxygenation rapidly normalized on room air. On postoperative day (POD) 3, the patient developed a high fever (39 °C), rising C-reactive protein (CRP; 14 mg/dL), abrupt leukopenia (15,300 → 3300/µL), and, several hours later, profuse watery diarrhea. At that time, an evaluation for an infectious source and escalation of therapy (e.g., blood cultures, serum lactate, and abdominal imaging) were not performed. In the early hours of POD 4, he suffered sudden desaturation, shock, and cardiac arrest, and died despite resuscitation. A portable radiograph after intubation showed no new diffuse pulmonary infiltrates but marked colonic gas distension. This case highlights the need to reassess diagnostic framing when discordant postoperative “red flags” emerge and proposes practical triggers for early sepsis evaluation and escalation—prioritizing early recognition and timely rescue rather than a definitive determination of the cause of death—in high-risk CSDH patients. Full article

Copper is widely used in two-phase devices for electronic cooling due to its ease of manufacture and high thermal conductivity. However, such high-heat conduction can limit the performance of pulsating heat pipes (PHPs) through transverse heat leakage. The use of lower-conductivity materials such as stainless steel enhances phase-change heat transfer by promoting stronger flow oscillations and reducing parasitic heat leakage, but it may be overall detrimental due to its poor thermal linkage between evaporator and condenser sections. Therefore, in this study, two main objectives are addressed: (i) experimentally characterizing the thermal behavior of a mini flat-plate PHP made of stainless steel (AISI 316L), and (ii) benchmarking its performance against a copper counterpart. Both devices were manufactured by diffusion bonding and tested under different orientations to evaluate operational robustness. The stainless steel PHP initiated oscillations at lower heat loads and showed larger temperature oscillations compared to the copper PHP, demonstrating effective phase-change heat transfer despite its lower thermal conductivity. A filling ratio of 71% of water provided the most stable operation, while orientation affected startup conditions and oscillation amplitude. Overall, stainless steel achieved comparable thermal performance to copper at low-to-moderate heat loads from 2.6 to 13.0 W/cm², with additional benefits including reduced mass (~11% lighter), higher mechanical strength, and corrosion resistance. These results indicate that stainless steel is a viable alternative to copper at least for miniature flat-plate PHPs, offering a balance between thermal efficiency, mechanical robustness, and operational reliability. Full article

The marine controlled-source electromagnetic (CSEM) method serves as an effective tool for detecting hydrocarbon reservoirs. However, it faces a key challenge in shallow water: the airwave, an EM signal lacking subsurface information, often obscures reservoir responses. Conventional CSEM analysis, conducted in the diffusive frequency domain (DFD), only captures the steady-state behavior of the airwave, limiting physical insight into its propagation. In this study, we introduce the fictitious wave domain (FWD) method to reinterpret and visualize the airwaves’ trajectory and attenuation, individually. By transforming diffusive EM fields into fictitious lossless propagating waves, the FWD enables the use of kinematic wave concepts such as reflection, refraction, and travel time. The airwave is clearly identified as a refracted wave generated when a transverse electromagnetic (TEM) mode wave impinges perpendicularly on the air–seawater interface. Its path and arrival time become directly observable, allowing clear separation from other wave types. This approach visualizes and extracts the airwave even in complex inhomogeneous seawater, enabling its accurate transformation back to the DFD. The FWD thus provides a powerful tool for enhancing interpretation in marine EM exploration and offers a theoretical foundation for the development of tailored marine electromagnetic sensors. Full article

Bamboo, a fast-growing and biodegradable industrial crop, exhibits excellent mechanical properties, which facilitate its widespread use in construction, furniture, and decorative applications. However, its inherently limited permeability hinders processing during drying, chemical modification, dyeing, and impregnation. Although previous studies have explored structural and treatment-related aspects, few have offered a comprehensive and integrative overview that bridges anatomical structure, permeation mechanisms, performance evaluation, and treatment strategies. This review synthesizes 126 publications from 1997 to 2024 to provide a comprehensive, multidimensional analysis of bamboo permeability. Structure–function relationships are examined by assessing how vessels, sieve tubes, perforation plates, pits, and bamboo nodes influence permeability, with an emphasis on quantitative correlations. Capillarity, diffusion, and viscous resistance are integrated into a unified theoretical framework, proposing a model that couples longitudinal capillary rise with transverse diffusion. Detection approaches, including both direct techniques (weight gain, microscopy, tracer elements, fluorescence imaging) and indirect techniques (porosity measurement, Micro-CT), with their respective advantages, limitations, and applications. Enhancement strategies are categorized into chemical, physical, and biological methods, with assessments of their effectiveness, environmental impact, and energy consumption. Overall, this review provides a holistic perspective on bamboo permeability and offers valuable guidance for future research and engineering applications. Full article

Magnetic nanoparticles (MNPs) perturb magnetic field homogeneity, influencing transverse relaxation and the full width at half maximum (FWHM) of nuclear magnetic resonance (NMR) spectra. In Nuclear Magnetic Resonance (NMR), this appears as decay of the free induction decay (FID) signal, whose relaxation rate determines spectral FWHM. In D₂O containing MNPs, both nanoparticles and solvent molecules undergo Brownian motion and diffusion. Under a vertical main field ($B_0$), MNPs respond to their magnetization behavior, evolving toward a dynamic steady state in which the time-averaged distribution of local field fluctuations remains stable. The resulting spatial magnetic field can thus characterize field homogeneity. Within this framework, Monte Carlo simulations of spatial field distributions approximate the dynamic environment experienced by nuclear spins. NMR experiments confirm that increasing MNP concentration and particle size significantly broadens FWHM, while stronger $B_0$ enhances sensitivity to MNP-induced inhomogeneities. Full article

Carbon fiber-reinforced polymer (CFRP) composites exhibit higher strength in the longitudinal direction than in the transverse direction of the fibers, making fiber orientation evaluation crucial. In this study, a method for evaluating fiber orientation using halogen spot-periodic heating and a non-lock-in-type infrared camera is employed and applied to a unidirectional carbon fiber composite—a CFRP composite with unidirectional continuous fibers. Consequently, the in-plane thermal diffusivity in the fiber direction is significantly higher than that in other directions. Therefore, the employed method successfully evaluates fiber orientation in unidirectional carbon fiber composites. Full article

We report a rare case of pulmonary tumor thrombotic microangiopathy (PTTM) in a patient with metastatic neurotrophic tropomyosin receptor kinase (NTRK) fusion-positive transverse colon cancer who exhibited a marked radiologic and biochemical response to entrectinib. Despite significant tumor shrinkage, progressive dyspnea and hypoxemia developed approximately four weeks after therapy initiation. Chest CT revealed diffuse interstitial infiltrates, initially interpreted as drug-induced pneumonitis or infection. Entrectinib was discontinued, but respiratory failure progressed, and the patient died shortly thereafter. Autopsy revealed widespread pulmonary microangiopathy with fibrocellular intimal proliferation and tumor emboli in small pulmonary arteries, consistent with PTTM. Notably, no hematogenous metastases were identified; instead, tumor spread appeared to occur via an atypical lymphatic route through the thoracic duct. The tumor exhibited microsatellite stability and a modest mutation burden, suggesting that lymphatic dissemination and microvascular pathology may progress independently of these genomic features. This case underscores a critical dissociation between oncologic response and vascular complications, indicating that tropomyosin receptor kinase (TRK) inhibitor monotherapy may be insufficient to prevent PTTM. Comprehensive management may require concurrent strategies targeting the pulmonary microvasculature, including antiangiogenic therapy and modulation of cytokine and growth factor signaling. Full article

High-order harmonic generation with mid-infrared laser fields has been considered the most promising method to produce soft X-rays attosecond pulses, which provides an important tool for probing the ultrafast electronic dynamics in atoms, molecules, and solids in real time. However, quantum diffusion of the electron wavepacket can lead to a dramatic drop of the harmonic yield when a mid-infrared laser field is used. Here we theoretically demonstrate that a spatially structured (SS) laser field can suppress quantum diffusion of the electron wavepacket and lead to a significant enhancement of high-order harmonic generation, compared with those generated by the spatially homogeneous (SH) laser field. The SS laser field is inhomogeneous in transverse direction perpendicular to the laser polarization and homogeneous in the polarization direction of the laser field. The electric field presents a valley structure. It is found that this valley structure can confine the electron wavepacket around the parent ion, prevent the electron wavepacket spreading, and finally lead to the significant enhancement of the high-order harmonics. Our results provide a novel method for controlling the ultrafast electron wavepacket dynamics of HHG. Full article

We advance a mathematical framework for collective conviction by deriving a continuum theory from the network-based model introduced by us recently. The resulting equation governs the evolution of belief through a degenerate anisotropic logistic–diffusion process, where diffusion slows as conviction saturates. In one spatial dimension, we prove global well-posedness, demonstrate spectral front pinning that arrests the spread of influence at finite depth, and construct explicit traveling-wave solutions. In two dimensions, we uncover a geometric mechanism of curvature–induced quenching, where belief propagation halts along regions of low effective mobility and curvature. Building on this insight, we formulate a variational principle for optimal control under resource constraints. The derived feedback law prescribes how to spatially allocate repression effort to maximize inhibition of front motion, concentrating resources along high-curvature, low-mobility arcs. Numerical simulations validate the theory, illustrating how localized suppression dramatically reduces transverse spread without affecting fast axes. These results bridge analytical modeling with societal phenomena such as protest diffusion, misinformation spread, and institutional resistance, offering a principled foundation for selective intervention policies in structured populations. Full article

As urbanization accelerates globally, higher education agglomeration (HEA) emerges as a critical mechanism for integrating regional economic theories with practical strategies, driving innovation and sustainable development. This paper examines how HEA promotes innovation, human capital accumulation, industrial restructuring, and equitable income distribution across 193 cities in the “Two Transverse and Three Lengthways” urban clusters from 2006 to 2020. Using dynamic panel regression and spatial econometric models, the results show that HEA yields significant local and spatial spillover benefits, particularly in core cities that facilitate knowledge diffusion and resource sharing. Heterogeneity analysis reveals that these positive spillovers are strongest in first-tier, highly developed clusters and third-tier, early-stage clusters but weaker or even negative in second-tier, rapidly expanding regions. These spatial effects grow over time, reflecting the evolving patterns of regional integration. Theoretically, the paper advances the understanding of spatial synergy and spillover mechanisms in HEA in urban clusters. Practically, the findings highlight the need to tailor higher education strategies to the developmental stage of each urban cluster to optimize resource allocation and foster inclusive growth. This paper provides policy insights for using HEA as a catalyst for coordinated urban development. Full article

This publication covers experimental investigations on the design resistance of arc-brazed fillet welds (CuAl7) on low-alloyed structural steel (S355) subject to predominantly static loading and regarding steel construction regulations (Eurocode). In current steel construction regulations, there is no standardized design approach for arc-brazed fillet welds available, so arc-brazed connections are rarely used despite the benefits they offer in several regards compared to conventionally welded connections. Therefore, a resistance model for arc-brazed fillet welds was calibrated based on tensile tests that were conducted on gas metal arc-brazed specimens with transverse and longitudinal fillet welds. Based on the statistical evaluation of the test results according to Annex D of EN 1990, a newly determined correlation factor β_b is proposed, which can be used for the static design of arc-brazed fillet welds made of CuAl7. This approach leads to a significantly higher calculated design resistance than previous non-standardized design approaches allowed. Also, it was found that the failure behavior of the fillet welds is critical for the design resistance of the joints and that there is a need for further investigations with regard to a targeted joint failure, which, analogous to welded fillet welds, should take place along the throat of the weld and not along the less resistant diffusion zone of the joint. Thus, the results underscore the potential for the use of arc-brazed connections in steel construction in regard to their load-bearing capacity, but also highlight the necessity of continued research regarding factors influencing their structural integrity. Full article

Background/Objectives: Ischemic colitis, typically caused by thrombosis or reduced blood flow in the inferior mesenteric artery, is the most common ischemic lesion at the colorectal level. This case contributes to existing knowledge by highlighting the rare co-occurrence of a thrombosed aortic aneurysm and ischemic colitis, pointing to a direct vascular etiology rather than a multifactorial or idiopathic cause. Methods: A thorough electronic search was conducted on PubMed to identify risk factors and etiological determinants of ischemic colitis. Results: We present the case of a 70-year-old male with diffuse abdominal pain and multiple cardiac comorbidities. A CT scan revealed aeroenteritis, aerocolia, fusiform aneurysmal dilation of the abdominal aorta (18 cm long, 7.3 cm in diameter, from below the renal arteries to the bifurcation), parietal thrombosis, a circulating lumen of 2.7 cm, and inferior mesenteric artery thrombosis. Intraoperatively, necrosis was found in the upper rectum, sigmoid colon, descending colon, and the middle third of the left transverse colon, with clear demarcation between healthy and necrotic tissue. A subtotal proctocolectomy with transverse colostomy was performed. Conclusions: This case highlights ischemic colitis as a vascular disorder, urging broader differential diagnosis when common causes are unclear. Timely imaging, a multidisciplinary approach, and attention to vascular risks are key to identifying rare causes like aneurysmal thrombosis. While thrombosed abdominal aortic aneurysms can cause mesenteric ischemia, their link to ischemic and ulcerative colitis is unique, emphasizing the importance of accurate risk assessment in treatment planning. Full article

Background and Clinical Significance: The occurrence of cerebral venous sinus thrombosis (CVST), both with or without thrombocytopenia, following COVID-19 vaccination, is well documented and more common in recipients of vector vaccines. Cases of CVST following immunization with the COVID-19 messenger RNA (mRNA) vaccine are rare; most of these cases occur within 28 days of the first dose of the vaccine. Case Presentation: We present the case of a 38-year-old male with a history of two episodes of deep vein thrombosis in the lower limbs, but without a specific thrombophilic condition, who developed CVST 13 days after the second dose of the Pfizer/BioNTech BNT162b2 vaccine. He suffered from diffuse tension-type headache of progressively increasing intensity, and his objective neurological findings were normal. Magnetic resonance venography showed thrombosis of the transverse and right sigmoid sinuses, and magnetic resonance imaging (MRI) of the brain revealed no cerebral infarction. Two months later, a follow-up MR venography showed partial recanalization of the affected sinuses, and a brain MRI showed no infarction. Conclusions: Given the temporal sequence and the absence of other possible causes, we speculate that the second dose of the COVID-19 BNT162b2 vaccine may have triggered the development of CVST. Full article