Hasil untuk "Physics"

Yingtao Zhang, Wenhe Li, Yang Wu et al.

The leakage detection of oil and gas is very important for the safe operation of pipelines. The existing working condition recognition methods have limitations in processing and capturing complex multi-category leakage signal characteristics. In order to improve the accuracy of oil and gas pipeline leakage detection, a multi-scale convolutional neural network-Transformer (MSCNN-Transformer)-based oil and gas pipeline leakage condition recognition method is proposed. Firstly, in order to capture the global information and nonlinear characteristics of the time series signal, STFT is used to generate the time-frequency image. Furthermore, in order to enrich the feature information from different dimensions, the one-dimensional signal and the two-dimensional time-frequency image are sampled by multi-scale convolution, and the global relationship is established by combining the multi-head attention mechanism of the Transformer module. Finally, the leakage signal is accurately identified by fusing features and classifiers. The experimental results show that the proposed method shows high performance on the GPLA-12 data set, and the recognition accuracy is 96.02%. Compared with other leakage signal recognition methods, the proposed method has obvious advantages.

André Guaraci DeVito-Moraes, Isabela Souza Vardasca, Miguel Peñarrocha-Diago et al.

This study investigates the mechanical and optical properties of monolithic zirconia used in dentistry, focusing on how different concentrations of yttrium oxide and varied sintering times affect the material. A critical trade-off in ceramics has been reported in the literature, in which increased crystalline content (like in zirconia) leads to higher mechanical strength but lower aesthetic translucency. However, detailed information on this trade-off process for different types of zirconia is lacking. A total of seven types of zirconia varying in yttria content (3 mol% to 5 mol%) were tested across four sintering protocols available in a laboratory zirconia sintering device: Slow (12 h), Standard (8 h), Fast (3.5 h), and Ultrafast (1.15 h). The primary findings indicate that while a higher yttria concentration correlates with lower flexural strength and high translucency, the sintering time generally did not compromise mechanical strength or color variation across most samples. Nevertheless, the Fast and Ultrafast protocols did significantly reduce the translucency of zirconia with a high concentration of yttrium oxide.

F. Salmon

Noé Lugaz

Abstract Are we moving into a new reality where the next human stepping onto a different world will utter “That's one small step for me, a giant leap for my country”? Is further tightening Heliophysics and space weather research to military endeavors the solution to the decrease in federal funding for Heliophysics in the US and the worldwide increase in military budget? I invite researchers to take the time to contemplate those issues and to continue pushing for an ethical, peaceful, cooperative, and curiosity‐driven space science and space weather research.

Raquel Ciérvide, Roberto Manchón, Daniela Angel et al.

BACKGROUND: This study evaluates practices and preferences in treating intact brain metastases with stereotactic-radiosurgery (SRS) among members of the SEOR-SRS_SBRT working group, focusing on clinical protocols, equipment usage, and treatment parameters. MATERIALS AND METHODS: A survey conducted via Google Forms targeted 149 group members, with responses collected from one representative per institution between April and May 2024. Respondents included radiation oncologists from Mexico, Argentina, Portugal, and Spain, and data analysis covered demographics, equipment, treatment protocols, immobilization techniques, dose schedules, image-guided radiation therapy (IGRT), and prescription criteria. RESULTS: Out of 149 members, 28 institutions responded. Most participants (64.5%) had over 10 years of experience. Single-fraction-SRS was practiced by 64.5%, while fractionated SRS-SRT was used by 96.8%. Linear accelerators (C-Linac) were the primary equipment (86.7%). Specific protocols for brain metastases were reported by 80%. SRS was preferred for 1–3 metastases (93.3%), while whole-brain radiation therapy (WBRT) was used for > 10 metastases (70%). Considering the type of stereotactic localization, frameless systems were employed in 69% while rigid-frames were used in 31% of cases. The most common immobilization technique was a reinforced mask (50%). Planning computed tomography (CT)/magnetic resonance imaging (MRI) slice thickness ≤ 2 mm was standard, and automatic registration was applied in 69%. Doses of 21–23 Gy were common for lesions < 1 cm, while < 20 Gy was typical for 2–3 cm lesions. Margins for single-fraction SRS were 1 mm in 50% of cases. IGRT verification used cone-beam CT (64.5%) and surface-guided radiation therapy (35.5%). CONCLUSION: The findings reveal variability in SRS practice, particularly in immobilization, dose prescriptions, and IGRT methods, emphasizing the need for standardized guidelines to optimize patient outcomes and adapt treatments to institutional resources and patient-specific factors.

Jia-Hui Wang, Maosheng Xiang, Ji-Feng Liu

Intergalactic wandering stars (IWSs) within 10 Mpc remain a poorly explored area of astronomy. Such stars, if they exist, are supposed to be wandering objects as they are not bound by the gravitational potential of any galaxy. We set out to conduct dedicated studies to unravel such a wandering stellar population. As the first paper of the series, in the present work, we model the distance distribution and luminosity function of IWSs formed via the Hills mechanism of the Galactic central massive black hole (GCMBH). We implement a numerical simulation to generate IWSs, taking the ejection history of the GCMBH and the stellar evolution process into consideration, and present their luminosity function in the distance range of 200 kpc–10 Mpc. Our results suggest that a few hundred thousand IWSs have been generated by the GCMBH via the Hills mechanism in the past 14 billion yr. These IWSs have an apparent magnitude peaking at 30–35 mag in the Sloan Digital Sky Survey r band, which are hard to detect. However, a few thousand of them at the bright end are detectable by upcoming wide-field deep surveys, such as the China Space Station Telescope and the Vera Rubin Observatory. The forthcoming discovery of such a wandering stellar population will open the door for a precise understanding of the matter constitution of the nearby intergalactic space and the dynamical history of galaxies in the local Universe.

Guang Li PhD, Victoria Yu PhD, Kaitlyn Ryan BS et al.

Purpose To improve the setup reproducibility of neck curvature using real-time optical surface imaging (OSI) guidance on 2 regions of interest (ROIs) to infer cervical spine (c-spine) curvature for surface-guided radiotherapy (SGRT) of head-and-neck (HN) and c-spine cancer. Methods A novel SGRT setup approach was designed to reproduce neck curvature with 2 ROIs: upper-chest ROI and open-face ROI. It was hypothesized that the neck curvature could be reproduced if both ROIs were aligned within ±3 mm/2˚ tolerance. This was tested prospectively in 7 volunteers using real-time 3D-OSI guidance and lateral 2D-photography verification after the 3D and 2D references were captured from the initial conventional setup. Real-time SGRT was performed to align chest-ROI and face-ROI, and the longitudinal distance between them was adjustable using a head-support slider. Verification of neck curvature anteriorly and posteriorly was achieved by overlaying edge-extracted lateral pictures. Retrospectively, the relationship between anterior surface and spinal canal alignment was checked in 11 patients using their simulation CT (simCT) and setup cone-beam CT (CBCT). After the anterior surface was rigidly aligned, the spinal canal alignment was checked and quantified using the mean-distance-to-agreement (MDA) and DICE similarity index, and surface-to-spine correlation was calculated. Results The reproducibility of neck curvatures using the 2xROI SGRT setup is verified and the mean neck-outline-matching difference is within ±2 mm in lateral photographic overlays. The chest-ROI alignment takes 110 ± 58 s and the face-ROI takes 60 ± 35 s. When the anterior body surface is aligned (MDA = 1.1 ± 0.6 mm, DICE = 0.96 ± 0.02,) the internal spinal canal is also aligned (MDA = 1.0 ± 0.3 mm, DICE = 0.84 ± 0.04) in 11 patients. The surface-to-spine correlation is c = 0.90 (MDA) and c = 0.85 (DICE). Conclusion This study demonstrates the feasibility of the novel 2-ROI SGRT setup technique to achieve reproducible neck and c-spine curvature regardless of neck visibility and availability as ROI. Staff training is needed to adopt this unconventional SGRT technique to improve patient setup.

Kaori Sánchez-Carrillo, David Quintanar-Guerrero, Miguel José-Yacamán et al.

L-lysine functionalized gold nanoparticles (AuNPs-Lys) have been widely used for the detection of worldwide interest analytes. In this work, a colorimetric assay for the detection of the carcinogen aflatoxin B1 (AFB1) based on the aggregation of AuNPs-Lys in the presence of copper ions was developed. For this purpose, AuNPs were synthesized in citrate aqueous solution, functionalized, and further characterized by UV–Vis, fluorescence, Fourier transform infrared spectroscopy (FTIR), nanoparticle tracking analysis (NTA), dynamic light scattering (DLS), and transmission electron microscopy (TEM). In general, AuNPS-Lys (~2.73 × 1011 particles) offered a clear colorimetric response in the presence of AFB1 and Cu2+ ions showing linearity in the range of 6.25 to 200 ng AFB1/mL, with a detection limit of 4.18 ng AFB1/mL via photometric inspection. Moreover, the performance of the proposed methodology was tested using the 991.31 AOAC official procedure based on monoclonal antibodies in maize samples artificially contaminated with AFB1. There was a good agreement between the measured AFB1 concentrations in both assays, the average recoveries for the colorimetric and immunoaffinity assays were between 91.2–98.4% and 96.0–99.2%, respectively. These results indicated that the colorimetric assay could be used as a rapid, eco-friendly, and cost-effective platform for the quantification of AFB1 in maize-based products.

Lei Hu, Yi-Feng Sun, Jie Cheng et al.

Two-dimensional (2D) semiconductors with intrinsic dipole show glorious prospects in the fields of nanoelectronics. Herein, the possible applications of single-layer GaInO3 in the realms of optoelectronics and piezoelectricity are investigated via the first-principles study. We find that single-layer GaInO3 exhibits a large vertical dipole moment and a direct bandgap (1.53 eV). Its transport mobility for electrons and holes both surpasses 2000 cm2·V−1·s−1. The effective separation of charge carriers for single-layer GaInO3 is confirmed by the strong inside electric field and the spatially isolated conduction band minimum (CBM) and valence band maximum (VBM). The allowed optical transition makes single-layer GaInO3 a hopeful candidate for optical absorbers and detectors. Finally, we also find that single-layer GaInO3 holds a prominently stronger out-of-plane piezoelectric effect than that of previous 2D materials and will play a big role in modern top-bottom gate technologies. In summary, this work proves that single-layer GaInO3 is a promising candidate for atomic-thick optoelectronic and piezoelectric devices.

Sameh Alsaqoor, Ahmad Alqatamin, Ali Alahmer et al.

This study examines the impact of incorporating phase change material (PCM) in photovoltaic thermal (PVT) systems on their electrical and thermal performance. Although PVT systems have shown effectiveness in converting solar energy into both electricity and heat, there is a necessity for studies to investigate how integrating PCMs can further enhance performance. The study also aims to explore the effect of solar irradiation and coolant mass flow rate on the electrical and thermal output of both PVT and PVT-PCM systems. A graphical user interface was developed within the MATLAB Simulink under the weather conditions of Amman, Jordan. The results show that the incorporation of PCM in PVT systems significantly reduces solar cell temperature and increases electrical efficiency. The highest electrical efficiency of a PVT system with PCM was found to be 14%, compared to 13.75% in a PVT system without PCM. Furthermore, the maximum achievable electrical power in a PVT system with PCM was 21 kW, while in the PVT system without PCM it was 18 kW. The study also found that increasing the coolant mass flow rate in a PVT system with PCM further reduced PV cell temperature and increased electrical efficiency, while the electrical efficiency of both the PVT and PVT-PCM systems decreases as solar incident radiation flux increases, resulting in a significant rise in cell temperature. At an increased solar radiation level from 500 W/m2 to 1000 W/m2, the electrical efficiency of the PVT configuration decreases from 13.75% to 11.1%, while the electrical efficiency of the PVT-PCM configuration falls from 14% to 12%. The findings of this study indicate that the use of PCM in PVT systems can lead to significant improvements in energy production and cooling processes. The results provide valuable information for designing and optimizing PVT-PCM systems.

Nara Guisoni, Luis Diambra

One of the most surprising mechanisms to explain the symmetry breaking phenomenon linked to pattern formation is known as Turing instabilities. These patterns are self-organising spatial structures resulting from the interaction of at least two diffusive species in specific conditions. The ideas of Turing have been used extensively in the specialised literature both to explain developmental patterns, as well as synthetic biology design. In the present work we study a previously proposed morphogenetic synthetic circuit consisting of two genes controlled by the same regulatory system. The spatial homogeneous version of this simple model presents a rich phase diagram, since it has a saddle-node bifurcation, spirals and limit cycle. Linear stability analysis and numerical simulations of the complete model allow us to determine the conditions for the development of Turing patterns, as well as transient patterns. We found that the parameter region where Turing patterns are found is much smaller than the region where transient patterns occur. We observed that the temporal evolution towards Turing patterns can present one or two different length scales, depending on the initial conditions. Further, we found a parameter region where the persistence time of the transient patterns depends on the distance between the parameters values on which the system is operating and the boundary of Turing patterns. This persistence time has a singularity at a critical distance that gives place to metastable patterns. To the best of our knowledge, transient and metastable patterns associated with Turing instabilities have not been previously reported in morphogenetic models.

Mena E. Y. Ekladious, Mounir Sobhy Guirguis, Ahmed Mohammed Haggag et al.

Abstract Background Multidetector computed tomography angiography (MDCT) is a non-invasive examination for coronary artery disease. Coronary artery disease reporting and data system (CAD-RADS) is a structured reporting system that successfully facilitated communication with clinicians. Our study aimed to assess the accuracy as well as the agreement of the CAD-RADS system with the conventional angiography results. Results 48 patients were enrolled in this prospective study, all patients underwent MDCT coronary angiography and conventional coronary artery angiography. An excellent inter method agreement between coronary CT angiography (CCTA) and conventional coronary angiography was noted for the left main trunk (LMT) with k = 1 (p < 0.001). An excellent inter method agreement was found for the proximal, mid- and distal segments of the left anterior descending artery (LAD) and the second diagonal segment, with k = 1, 0.842 0.886 and 0.886, respectively (p < 0.001). A good agreement was noted at the first diagonal segment with k = 0.765 (p < 0.001). An excellent inter-method agreement was found for the proximal, mid- and distal segments of the left circumflex artery (LCx) and the obtuse marginal branch, with k = 0.838, 0.846, 1 and 0.846, respectively (p < 0.001). An excellent agreement was found for the proximal and mid-segments of the right coronary artery (RCA) and the posterior descending artery, with k = 1 for all segments (p < 0.001), yet a good agreement was noted at its distal segment with k = 0.782 (p < 0.001). The overall per-patient sensitivity, specificity and accuracy of the CT coronary angiography were 92.9%, 90% and 91.7% respectively. Conclusions The CAD-RADS algorithm and invasive coronary angiography agreed perfectly; thus, CT coronary angiography can be used as the first screening test and the invasive coronary angiography can be spared for cases requiring intervention.

Alexandre Krebs, Yannick Benezeth, Thomas Bazin et al.

In this paper, we are interested in the in vivo detection of pre-cancerous stomach lesions. Pre-cancerous lesions are unfortunately rarely explored in research papers as most of them are focused on cancer detection or conducted <i>ex-vivo</i>. For this purpose, a novel prototype is introduced. It consists of a standard endoscope with multispectral cameras, an optical setup, a fiberscope, and an external light source. Reflectance spectra are acquired in vivo on 16 patients with a healthy stomach, chronic gastritis, or intestinal metaplasia. A specific pipeline has been designed for the classification of spectra between healthy mucosa and different pathologies. The pipeline includes a wavelength clustering algorithm, spectral features computation, and the training of a classifier in a &#8220;leave one patient out&#8221; manner. Good classification results, around 80%, have been obtained, and two attractive wavelength ranges were found in the red and near-infrared ranges: [745, 755 nm] and [780, 840 nm]. The new prototype and the associated results give good arguments in favor of future common use in operating rooms, during upper gastrointestinal exploration of the stomach for the detection of stomach diseases.

Mohammed L. Jabbar, Abbas Shwya Alwan

Chopper is an important component in optical system. It represents a device, which changes the angle between the coordinate and vision lines of the target for the electrical signal. The chopper modulates the optical signal by a frequency dependent on the number and sectors shapes. The optical modulator takes shapes of various circular due to the need for it. Through this study we have designed the fractal optical modulator its two circles inner and outer, each circle involving in eighteen sectors, by building a computer program using visual basic language. In this paper, we assume that nine sectors one opaque and the other nine sectors are transmitted for the light. Even though the importance of the modulation transfers function (MTF) in testing and evaluating optical systems, it becomes the dependent measurement to know efficiency of the optical systems. It has been studied for optical systems at circular apertures, where that function could evaluate the image efficiency for point object in image planes at different magnitude of a radius and time. The fractal reticle have been designed of insulator material by using the fractal function. Then , evaluating the values of MTF at different values of a radius and time. Also we studied relation between number of sections and spatial frequency.

Ara Ko, Eun Sun Lee, Hyun Jeong Park et al.

Zinner’s syndrome is a rare congenital abnormality of the mesonephric duct. Unilateral renal agenesis, ipsilateral seminal vesicle cyst, and ipsilateral ejaculatory duct obstruction are the triad of maldevelopment of the mesonephric duct which comprises Zinner's syndrome. It is an extremely rare case, in that approximately 100 cases only have been reported worldwide. We discovered a rare developmental anomaly with other mesonephric duct-associated abnormalities, Zinner’s syndrome with a presumed ectopic prostate and triorchidism and do report here.

Xue-Si Li, Shu-Feng Zhang, Xue-Rui Sun et al.

We study the quantum transport behavior of a normal-superconductor-normal junction based on a type-II Weyl semimetal, which is arranged in the tilting direction of the Weyl semimetal. We find that both the crossed Andreev reflection and normal reflection are forbidden, while there will be double Andreev reflections and double electron transmissions for the incident electron from the semimetal side. Andreev reflections and transmissions occur both in the retro and specular directions simultaneously, symmetric about the normal of the interface but with different amplitudes, depending on the angle and energy of incident electrons. These transport processes make the junction here quite different from that based on the normal metal or graphene. In addition, the differential conductance is studied for experimental signatures. We find that the conductance is almost unaffected by the electrostatic potential in the normal region and it is enhanced with increasing junction length.

Ivana Stiperski, Stefano Serafin, Alexandre Paci et al.

In this article, we present an overview of the HyIV-CNRS-SecORo (Hydralab IV-CNRS-Secondary Orography and Rotors Experiments) laboratory experiments carried out in the CNRM (Centre National de Recherches Météorologiques) large stratified water flume. The experiments were designed to systematically study the influence of double obstacles on stably stratified flow. The experimental set-up consists of a two-layer flow in the water tank, with a lower neutral and an upper stable layer separated by a sharp density discontinuity. This type of layering over terrain is known to be conducive to a variety of possible responses in the atmosphere, from hydraulic jumps to lee waves and highly turbulent rotors. In each experiment, obstacles were towed through the tank at a constant speed. The towing speed and the size of the tank allowed high Reynolds-number flow similar to the atmosphere. Here, we present the experimental design, together with an overview of laboratory experiments conducted and their results. We develop a regime diagram for flow over single and double obstacles and examine the parameter space where the secondary obstacle has the largest influence on the flow. Trapped lee waves, rotors, hydraulic jumps, lee-wave interference and flushing of the valley atmosphere are successfully reproduced in the stratified water tank. Obstacle height and ridge separation distance are shown to control lee-wave interference. Results, however, differ partially from previous findings on the flow over double ridges reported in the literature due to the presence of nonlinearities and possible differences in the boundary layer structure. The secondary obstacle also influences the transition between different flow regimes and makes trapped lee waves possible for higher Froude numbers than expected for an isolated obstacle.

Y. Nobuta, S. Masuzaki, M. Tokitani et al.

In the present study, an additional deuterium (D) ion irradiation was performed against long-term samples mounted on the helical coil can and in the outer private region in the LHD during the 17th experimental campaign. Based on the release behavior of the D and hydrogen (H) retained during the experimental campaign, the difference of release behavior at the top surface and in bulk of modified surfaces is discussed. Almost all samples on the helical coil can were erosion-dominant and some samples were covered with boron or carbon, while a very thick carbon films were formed in the outer private region. In the erosion-dominant area, the D desorbed at much lower temperatures compared to that of H retained during the LHD plasma operation. For the samples covered with boron, the D tended to desorb at lower temperatures compared to H. For the carbon deposition samples, the D desorbed at much higher temperatures compared to no deposition and boron-covered samples, which was very similar to that of H. The D retention capabilities at the top surface of carbon and boron films were 2–3 times higher than no deposition area. The results indicate that the retention and release behavior at the top surface of the modified layer can be different from that of bulk substrate material. Keywords: Hydrogen retention, Desorption, Redeposition, Long-term sample, LHD

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