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45 pages, 9840 KiB  
Article
A 1.8 m Class Pathfinder Raman LIDAR for the Northern Site of the Cherenkov Telescope Array Observatory—Performance
by Pedro José Bauzá-Ruiz, Oscar Blanch, Paolo G. Calisse, Anna Campoy-Ordaz, Sidika Merve Çolak, Michele Doro, Lluis Font, Markus Gaug, Roger Grau, Darko Kolar, Camilla Maggio, Manel Martinez, Samo Stanič, Santiago Ubach, Marko Zavrtanik and Miha Živec
Remote Sens. 2025, 17(11), 1815; https://doi.org/10.3390/rs17111815 - 22 May 2025
Viewed by 673
Abstract
The Barcelona Raman LIDAR (BRL) will provide continuous monitoring of the aerosol extinction profile along the line of sight of the Cherenkov Telescope Array Observatory (CTAO). It will be located at its Northern site (CTAO-N) on the Observatorio del Roque de Los Muchachos. [...] Read more.
The Barcelona Raman LIDAR (BRL) will provide continuous monitoring of the aerosol extinction profile along the line of sight of the Cherenkov Telescope Array Observatory (CTAO). It will be located at its Northern site (CTAO-N) on the Observatorio del Roque de Los Muchachos. This article presents the performance of the pathfinder Barcelona Raman LIDAR (pBRL), a prototype instrument for the final BRL. Power budget simulations were carried out for the pBRL operating under various conditions, including clear nights, moon conditions, and dust intrusions. The LIDAR PreProcessing (LPP) software suite is presented, which includes several new statistical methods for background subtraction, signal gluing, ground layer and cloud detection and inversion, based on two elastic and one Raman lines. Preliminary test campaigns were conducted, first close to Barcelona and later at CTAO-N, albeit during moonlit nights only. The pBRL, under these non-optimal conditions, achieves maximum ranges up to about 35 km, range resolution of about 50 m for strongly absorbing dust layers, and 500 m for optically thin clouds with the Raman channel only, leading to similar resolutions for the LIDAR ratios and Ångström exponents. Given the reasonable agreement between the extinction coefficients obtained from the Raman and elastic lines independently, an accuracy of aerosol optical depth retrieval in the order of 0.05 can be assumed with the current setup. The results show that the pBRL can provide valuable scientific results on aerosol characteristics and structure, although not all performance requirements could be validated under the conditions found at the two test sites. Several moderate hardware improvements are planned for its final upgraded version, such as gated PMTs for the elastic channels and a reduced-power laser with a higher repetition rate, to ensure that the data acquisition system is not saturated and therefore not affected by residual ringing. Full article
(This article belongs to the Special Issue Remote Sensing: 15th Anniversary)
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19 pages, 2116 KiB  
Article
Right Parietal rTMS Induces Bidirectional Effects of Selective Attention upon Object Integration
by Markus Conci, Leonie Nowack, Paul C. J. Taylor, Kathrin Finke and Hermann J. Müller
Brain Sci. 2025, 15(5), 483; https://doi.org/10.3390/brainsci15050483 - 3 May 2025
Viewed by 633
Abstract
Background/Objectives: Part-to-whole object completion and search guidance by salient, integrated objects has been proposed to require attentional resources, as shown by studies of neglect patients suffering from right-parietal brain damage. The current study was performed to provide further causal evidence for the link [...] Read more.
Background/Objectives: Part-to-whole object completion and search guidance by salient, integrated objects has been proposed to require attentional resources, as shown by studies of neglect patients suffering from right-parietal brain damage. The current study was performed to provide further causal evidence for the link between attention and object integration. Methods: Healthy observers detected targets in the left and/or right hemifields, and these targets were in turn embedded in various Kanizsa-type configurations that systematically varied in the extent to which individual items could be integrated into a complete, whole object. Moreover, repetitive transcranial magnetic stimulation (rTMS) was applied over the right intraparietal sulcus (IPS) and compared to both active and passive baseline conditions. Results: The results showed that target detection was substantially facilitated when the to-be detected item(s) were fully embedded in a salient, grouped Kanizsa figure, either a unilateral triangle or a bilateral diamond. However, object groupings in one hemifield did not facilitate target detection to the same extent when there were bilateral targets, one inside the (triangle) grouping and the other outside of the grouped object. These results extend previous findings from neglect patients. Moreover, a subgroup of observers was found to be particularly sensitive to IPS stimulation, revealing neglect-like extinction behavior with the single-hemifield triangle groupings and bilateral targets. Conversely, a second subgroup showed the opposite effect, namely an overall, IPS-dependent improvement in performance. Conclusions: These explorative analyses show that the parietal cortex, in particular IPS, seems to modulate the processing of object groupings by up- and downregulating the deployment of attention to spatial regions were to-be-grouped items necessitate attentional resources for object completion. Full article
(This article belongs to the Section Cognitive, Social and Affective Neuroscience)
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9 pages, 1934 KiB  
Communication
Four-Channel Nanosecond Pulse Combination in the Non-Polarization-Maintaining Fiber System
by Xinyu Wang, Qiang Shu, Qiuhui Chu, Chenxu Liu, Yuefang Yan, Jing Wen, Kegong Dong, Rumao Tao, Haoyu Zhang, Honghuan Lin and Jianjun Wang
Photonics 2025, 12(4), 363; https://doi.org/10.3390/photonics12040363 - 10 Apr 2025
Viewed by 334
Abstract
We report a novel coherent nanosecond pulse combination approach using four-channel non-polarization-maintaining large-mode-area (LMA) Ytterbium-doped (Yb-doped) fiber amplifiers. The stochastic parallel gradient descent (SPGD) and frequency dithering algorithm are introduced to stabilize the synchronization in polarizations and phases among all the channels. The [...] Read more.
We report a novel coherent nanosecond pulse combination approach using four-channel non-polarization-maintaining large-mode-area (LMA) Ytterbium-doped (Yb-doped) fiber amplifiers. The stochastic parallel gradient descent (SPGD) and frequency dithering algorithm are introduced to stabilize the synchronization in polarizations and phases among all the channels. The system delivers an average power of ~250 W and a pulse duration of 4 ns with a combination efficiency of around 87% when the repetition rate of a single pulse is limited to 1 MHz, the polarization extinction ratio (PER) at 30 μm core diameter and 250 μm cladding diameter remains around 96%. Full article
(This article belongs to the Special Issue Advances in Ultrafast Science and Applications)
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9 pages, 1394 KiB  
Article
Sub-200 fs Polarization-Maintaining All-Fiber Thulium-Doped Dissipative Soliton Fiber Laser System at 1920 nm
by Timothy Lim, Shutao Xu, Lachlan Hooper, Maria Davey and Michelle Y. Sander
Photonics 2025, 12(4), 361; https://doi.org/10.3390/photonics12040361 - 10 Apr 2025
Viewed by 560
Abstract
A polarization-maintaining all-fiber laser source based on a nonlinear amplifying loop mirror with broadband operation (64 nm) around 1920 nm is demonstrated. The oscillator can generate 66 pJ up-chirped dissipative soliton pulses at a repetition rate of 22.8 MHz with a high polarization [...] Read more.
A polarization-maintaining all-fiber laser source based on a nonlinear amplifying loop mirror with broadband operation (64 nm) around 1920 nm is demonstrated. The oscillator can generate 66 pJ up-chirped dissipative soliton pulses at a repetition rate of 22.8 MHz with a high polarization extinction ratio of 17 dB. By adding a polarization controller to the polarization-maintaining dispersion-compensating fiber, the filter behavior can be adjusted allowing for the tuning of the emission to a center wavelength of 1878 nm, 1907 nm, and 1926 nm. Using an all-polarization-maintaining single-mode fiber amplifier with anomalous dispersion, the pulses are amplified to 0.9 nJ and compressed to a near Fourier-limited pulse duration of 170 fs with a peak power of 4.3 kW. Such all-fiber-based sources are attractive due to their compact size, high beam quality, and good environment stability. Full article
(This article belongs to the Special Issue Optical Fiber Lasers and Laser Technology)
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16 pages, 9709 KiB  
Article
Al Doping Effect on Enhancement of Nonlinear Optical Absorption in Amorphous Bi2Te3 Thin Films
by Tengfei Zhang, Shenjin Wei, Shubo Zhang, Menghan Li, Jiawei Wang, Jingze Liu, Junhua Wang, Ertao Hu and Jing Li
Materials 2025, 18(6), 1372; https://doi.org/10.3390/ma18061372 - 20 Mar 2025
Viewed by 467
Abstract
Bismuth telluride (Bi2Te3) has attracted significant attention due to its broadband ultrafast optical response and strong nonlinearity at high laser fluence in the field of optoelectronic materials. The objective of this work is to study the effect of Al [...] Read more.
Bismuth telluride (Bi2Te3) has attracted significant attention due to its broadband ultrafast optical response and strong nonlinearity at high laser fluence in the field of optoelectronic materials. The objective of this work is to study the effect of Al doping on the structure, linear optical properties, and nonlinear optical absorption behavior of Bi2Te3 thin films. The amorphous Al-doped Bi2Te3 thin films with varying Al doping concentrations were prepared using magnetron co-sputtering. The structure and linear optical properties were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and UV/Vis/NIR spectrophotometry. The third-order nonlinear optical absorption properties of Al: Bi2Te3 thin films were investigated using the open-aperture Z-scan system with a 100 fs laser pulse width at a wavelength of 800 nm and a repetition rate of 1 kHz. The results indicate that Al dopant reduces both the refractive index and extinction coefficient and induces a redshift in the optical bandgap. The optical properties of the films can be effectively modulated by varying the Al doping concentration. Compared with undoped Bi2Te3 thin films, Al-doped Bi2Te3 thin films exhibit larger nonlinear optical absorption coefficients and higher damage thresholds and maintaining high transmittance. These findings provide experimental evidence and a reliable approach for the further optimization and design of ultrafast nonlinear optical devices. Full article
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22 pages, 14839 KiB  
Article
Forecasting Suitable Habitats of the Clouded Leopard (Neofelis nebulosa) in Asia: Insights into the Present and Future Climate Projections Within and Beyond Extant Boundaries
by Imon Abedin, Hilloljyoti Singha, Hye-Eun Kang, Hyun-Woo Kim and Shantanu Kundu
Biology 2024, 13(11), 902; https://doi.org/10.3390/biology13110902 - 5 Nov 2024
Cited by 3 | Viewed by 2669
Abstract
Terrestrial carnivores, such as the clouded leopard (Neofelis nebulosa), are ‘vulnerable’ and experiencing significant population declines in mainland Asia. Considering the assessed threats, the IUCN has repetitively revised the range of this felid and now characterized it into four distinct categories [...] Read more.
Terrestrial carnivores, such as the clouded leopard (Neofelis nebulosa), are ‘vulnerable’ and experiencing significant population declines in mainland Asia. Considering the assessed threats, the IUCN has repetitively revised the range of this felid and now characterized it into four distinct categories (extant, possibly extant, possibly extinct, and extinct). Although several ecological works have been accomplished on this enigmatic carnivore, the overall view of its habitat suitability, fragmentation, and corridor connectivity in both present and historical ranges is lacking. Thus, achieving this ecological information under present and future climate scenarios is crucial. The model identified merely 44,033 sq. km falling within the extant range (representing 31.66%) and 20,034 sq. km (8.13%) in the possibly extant range. Fascinatingly, within the historical ranges, an additional 15,264 sq. km (6.58%) has been identified as suitable habitat in the possibly extinct range and 14,022 sq. km (2.38%) in the extinct range. Notably, a total of 25,614 sq. km of suitable habitat is found within designated protected areas across the entire range. Nevertheless, climate change is expected to drive habitat loss of up to 41% (overall IUCN range) for N. nebulosa in both present and historical extent, with habitat patches becoming increasingly fragmented. This is reflected in a projected decline in the number of viable habitat patches (NP) by up to 23.29% in the future. This study also identified 18 transboundary biological corridors for N. nebulosa, with Southeast Asian countries expected to experience the most significant declines in corridor connectivity. In contrast, the South Asian countries (Bhutan, Nepal, and India) are projected to maintain relatively higher connectivity in the future. Nevertheless, a substantial decline in overall mean corridor connectivity is projected in the near future due to the impacts of climate change. This study underscores the urgent need for a coordinated and multifaceted conservation strategy for N. nebulosa, focusing on mitigating habitat loss and fragmentation. Practical measures must be implemented to protect the species’ shrinking range, considering its declining corridor networks and heightened vulnerability to inbreeding depression. Moreover, the assessment of habitat suitability both within and beyond the extant range, alongside corridor connectivity measures, provides valuable insights into potential translocation and reintroduction sites for this species. These findings provide a critical foundation for developing a strategic conservation plan tailored to the specific needs of this felid species across South and Southeast Asia, ensuring enhanced climate resilience and mitigating associated threats. Full article
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16 pages, 1990 KiB  
Article
Rats Lacking the Dopamine Transporter Display Inflexibility in Innate and Learned Behavior
by Anastasia Belskaya, Natalia Kurzina, Artem Savchenko, Ilya Sukhanov, Arina Gromova, Raul R. Gainetdinov and Anna Volnova
Biomedicines 2024, 12(6), 1270; https://doi.org/10.3390/biomedicines12061270 - 7 Jun 2024
Cited by 4 | Viewed by 2232
Abstract
Playing a key role in the organization of striatal motor output, the dopamine (DA)-ergic system regulates both innate and complex learned behaviors. Growing evidence clearly indicates the involvement of the DA-ergic system in different forms of repetitive (perseverative) behavior. Some of these behaviors [...] Read more.
Playing a key role in the organization of striatal motor output, the dopamine (DA)-ergic system regulates both innate and complex learned behaviors. Growing evidence clearly indicates the involvement of the DA-ergic system in different forms of repetitive (perseverative) behavior. Some of these behaviors accompany such disorders as obsessive–compulsive disorder (OCD), Tourette’s syndrome, schizophrenia, and addiction. In this study, we have traced how the inflexibility of repetitive reactions in the recently developed animal model of hyper-DA-ergia, dopamine transporter knockout rats (DAT-KO rats), affects the realization of innate behavior (grooming) and the learning of spatial (learning and reversal learning in T-maze) and non-spatial (extinction of operant reaction) tasks. We found that the microstructure of grooming in DAT-KO rats significantly differed in comparison to control rats. DAT-KO rats more often demonstrated a fixed syntactic chain, making fewer errors and very rarely missing the chain steps in comparison to control rats. DAT-KO rats’ behavior during inter-grooming intervals was completely different to the control animals. During learning and reversal learning in the T-maze, DAT-KO rats displayed pronounced patterns of hyperactivity and perseverative (stereotypical) activity, which led to worse learning and a worse performance of the task. Most of the DAT-KO rats could not properly learn the behavioral task in question. During re-learning, DAT-KO rats demonstrated rigid perseverative activity even in the absence of any reinforcement. In operant tasks, the mutant rats demonstrated poor extinction of operant lever pressing: they continued to perform lever presses despite no there being reinforcement. Our results suggest that abnormally elevated DA levels may be responsible for behavioral rigidity. It is conceivable that this phenomenon in DAT-KO rats reflects some of the behavioral traits observed in clinical conditions associated with endogenous or exogenous hyper-DA-ergia, such as schizophrenia, substance abuse, OCD, patients with Parkinson disease treated with DA mimetics, etc. Thus, DAT-KO rats may be a valuable behavioral model in the search for new pharmacological approaches to treat such illnesses. Full article
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19 pages, 2606 KiB  
Article
In Vitro Shoot Regeneration and Callogenesis of Sechium compositum (Donn. Sm.) C. Jeffrey for Plant Conservation and Secondary Metabolites Product
by Riviello-Flores María de la Luz, Castillo-Martínez Carlos Román, Cadena-Iñiguez Jorge, Ruiz-Posadas Lucero del Mar, Soto-Hernández Ramón Marcos, Arévalo-Galarza Ma. de Lourdes and Castillo-Juárez Israel
Horticulturae 2024, 10(6), 537; https://doi.org/10.3390/horticulturae10060537 - 21 May 2024
Cited by 1 | Viewed by 1837
Abstract
Sechium compositum (Cucurbitaceae) is a wild species that is distributed in the Soconusco region, Chiapas, Mexico, and the border with Guatemala. This species has an intangible biochemical value resulting from the pharmacological relevance of its secondary metabolites. However, as a consequence of the [...] Read more.
Sechium compositum (Cucurbitaceae) is a wild species that is distributed in the Soconusco region, Chiapas, Mexico, and the border with Guatemala. This species has an intangible biochemical value resulting from the pharmacological relevance of its secondary metabolites. However, as a consequence of the lack of knowledge about its importance, it is being displaced from its habitat at an accelerated rate, incurring the risk of genetic loss. Therefore, an in vitro culture protocol with two experimental phases was evaluated to propagate, conserve, and regenerate this species. The first phases considered the shoot propagation, adding seven concentrations (0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 mg mL−1) of 6-benzylaminopurine (BA) and thidiazuron (TDZ) and evaluating the number of buds and shoots and the shoot height. The best multiplication response was recorded with 0.1, 0.2, 0.4, and 1.0 mg L−1 of BA and 0.1 mg L−1 of TDZ, as well as the MS base culture medium. The validation of the results of the first phase (0.1 mg L−1 of BA) was compared with the MS in an independent experiment against the control (n = 50 repetitions), obtaining a height of 52 mm, 1.36 shoots, and 9.22 buds, suggesting that this concentration is adequate for the purpose, surpassing the MS control (MS culture medium alone). Of the total volume of roots obtained with packed bud structure in the previous experimental sample, it was reduced to 14% (n = 50). The second phase consisted of inducing callus formation from stem and leaf explants through the addition of 0.5, 1.0, and 2.0 mg L−1 of TDZ and 2,4-Dichlorophenoxyacetic acid (2,4-D) to the medium. Callus induction in S. compositum was better when using the stem in a medium with 2.0 mg L−1 of 2,4-D with a value of 97.8% around the explant. The addition of 500 mg L−1 of polyvinylpyrrolidone (PVP) is also suggested to reduce oxidation. This protocol represents a significant advance in the conservation, multiplication, and callus formation of S. compositum and contributes to its rescue and revaluation in the face of the danger of extinction. Full article
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35 pages, 6486 KiB  
Review
A Review on Micro-Combustion Flame Dynamics and Micro-Propulsion Systems
by David M. Dias, Pedro R. Resende and Alexandre M. Afonso
Energies 2024, 17(6), 1327; https://doi.org/10.3390/en17061327 - 10 Mar 2024
Cited by 3 | Viewed by 3624
Abstract
This work presents a state-of-the-art review of micro-combustion flame dynamics and micro propulsion systems. In the initial section, we focus in on the different challenges of micro-combustion, investigating the typical length and time scales involved in micro-combustion and some critical phenomena such as [...] Read more.
This work presents a state-of-the-art review of micro-combustion flame dynamics and micro propulsion systems. In the initial section, we focus in on the different challenges of micro-combustion, investigating the typical length and time scales involved in micro-combustion and some critical phenomena such as flammability limits and the quenching diameter.We present an extensive collection of studies on the principal types of micro-flame dynamics, including flashback, blow-off, steady versus non-steady flames, mild combustion, stable flames, flames with repetitive extinction, and ignition and pulsatory flame burst. In the final part of this review, we focus on micropropulsion systems, their performance metrics, conventional manufacturing methods, and the advancements in Micro-Electro-Mechanical Systems manufacturing. Full article
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14 pages, 4221 KiB  
Article
A Novel Continuous-Variable Quantum Key Distribution Scheme Based on Multi-Dimensional Multiplexing Technology
by Shuai Zhang, Heng Wang, Yan Pan, Yun Shao, Tao Zhang, Wei Huang, Yang Li and Bingjie Xu
Appl. Sci. 2024, 14(2), 934; https://doi.org/10.3390/app14020934 - 22 Jan 2024
Viewed by 1759
Abstract
Dual-polarization division multiplexing (DPDM) is considered to be a potential method to boost the secure key rate (SKR) of the continuous-variable quantum key distribution (CV-QKD) system. In this article, we propose a pilot alternately assisted local local oscillator (LLO) CV-QKD scheme based on [...] Read more.
Dual-polarization division multiplexing (DPDM) is considered to be a potential method to boost the secure key rate (SKR) of the continuous-variable quantum key distribution (CV-QKD) system. In this article, we propose a pilot alternately assisted local local oscillator (LLO) CV-QKD scheme based on multi-dimensional multiplexing, where time division multiplexing and frequency division multiplexing are combined with dual-polarization multiplexing techniques to dramatically isolate the quantum signal from the pilot tone. We establish a general excess noise model for the LLO CV-QKD system to analyze the influence mechanism of various disturbances (e.g., time-domain diffusion, frequency-domain modulation residual, and polarization perturbation) on the key parameters, such as the channel transmittance and excess noise. Specifically, the photon leakage noise from the reference path to the quantum path and that between quantum signals with two different polarization paths are simultaneously analyzed in the dual-polarization LLO CV-QKD scheme for the first time. Furthermore, a series of simulations are established to verify the performance of the proposed scheme. The results show that the maximal isolation degree achieves 84.0 dB~90.4 dB, and the crosstalk between pilot tones and quantum signals can be suppressed to a very small range. By optimizing the system parameters (e.g., modulation variance and repetition frequency), the SKR with 12.801 Mbps@25 km is achieved under the infinite polarization extinction ratio (PER) and 30 dB residual ratio of the frequency modulation in the nanosecond-level pulse width. Moreover, the performance of the proposed DPDM CV-QKD scheme under relatively harsh conditions is simulated; the results show that the SKR with 1.02 Mbps@25 km is achieved under a relatively low PER of 17 dB with the nanosecond-level pulse width and 20 dB residual ratio of the frequency modulation. Our work lays an important theoretical foundation for the practical DPDM LLO CV-QKD system. Full article
(This article belongs to the Special Issue Advanced Technologies in Data and Information Security III)
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22 pages, 3064 KiB  
Article
Characterization and Origin of Basalt-Derived Carnelian in the Mesozoic Newark Basin, New Jersey, USA
by Richard A. Volkert, Matthew L. Gorring, William H. Peck and Scott D. Stanford
Minerals 2023, 13(10), 1249; https://doi.org/10.3390/min13101249 - 24 Sep 2023
Cited by 1 | Viewed by 2660
Abstract
Carnelian occurs locally in New Jersey in the Newark basin as medium- to coarse-size pebbles in fluvial gravel and alluvium and colluvium formed from erosion of Lower Jurassic Preakness Basalt. Vesicles and molds of glauberite are preserved on lower surfaces and botryoidal textures [...] Read more.
Carnelian occurs locally in New Jersey in the Newark basin as medium- to coarse-size pebbles in fluvial gravel and alluvium and colluvium formed from erosion of Lower Jurassic Preakness Basalt. Vesicles and molds of glauberite are preserved on lower surfaces and botryoidal textures on the upper surfaces of some pieces. The microstructure consists of length-fast chalcedony characterized by parallel fibrous bundles overlain by repetitive, wavy extinction bands. Only peaks of ɑ-quartz and minor moganite are recognized in X-ray diffraction patterns. Carnelian contains 97–98 wt.% SiO2, ~1.0 wt.% Fe2O3, and 1.0–1.4 wt.% LOI; other major elements are <0.1 wt.%. Trace element abundances are low except for Y, Nb, Ta, W, Th, and U. Rare earth element (REE) patterns display heavy REE enrichment and large negative Eu anomalies. Most trace elements were mobilized from Proterozoic sources, whereas Si was likely derived from the alteration of basaltic glass in the Preakness. Carnelian δ18OVSMOW values are high and range from +18.3 to +31.2‰, comparable to global occurrences of volcanic rock-derived chalcedony. We propose that carnelian precipitated in the first Preakness flow from the mixing of hydrothermal fluid with meteoric water under conditions of low temperature (20–80 °C) and neutral to slightly alkaline pH. Full article
(This article belongs to the Special Issue Advances in Low-Temperature Mineralogy and Geochemistry)
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13 pages, 2488 KiB  
Article
Deep Learning and Long-Duration PRPD Analysis to Uncover Weak Partial Discharge Signals for Defect Identification
by Chien-Hsun Chen and Chih-Ju Chou
Appl. Sci. 2023, 13(19), 10570; https://doi.org/10.3390/app131910570 - 22 Sep 2023
Cited by 3 | Viewed by 2203
Abstract
This study focuses on improving the defect recognition accuracy under weak partial discharges (PDs) in epoxy resin through phase-resolved partial discharge (PRPD) analysis. The method is to refine the data rather than enhance the algorithm. Two measurement conditions are compared until PRPD pattern [...] Read more.
This study focuses on improving the defect recognition accuracy under weak partial discharges (PDs) in epoxy resin through phase-resolved partial discharge (PRPD) analysis. The method is to refine the data rather than enhance the algorithm. Two measurement conditions are compared until PRPD pattern saturation is achieved: one-minute and one-hour durations. The PD data specifically target three void types located at different positions within the epoxy material. The aim is to evaluate how the presence of weak PDs at the PD extinction voltage (PDEV) influences defect recognition accuracy. This research sheds light on the potential implications of neglecting the significance of weak PD signals in defect detection. A convolutional neural network (CNN) model is trained using PRPD data recorded at the repetitive PD inception voltage (RPDIV) and tested using the new PRPD data from both conditions recorded from a lower PDIV to a PDEV. The trained CNN model achieves a defect recognition accuracy of 100% for a one-hour duration, highlighting the importance of not neglecting weak PD signals. This emphasizes the significance of extended measurement duration and pattern saturation in capturing and analyzing weak PD signals for an improved defect recognition. This study contributes to the advancement of practical applications by understanding the behavior of the epoxy material and enhancing defect detection techniques. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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24 pages, 6315 KiB  
Article
Investigating the Ignition and Stability Limits of Premixed Methane/Air Combustion in Micro-Channels
by Almoutazbellah Kutkut, Mohsen Ayoobi, Marc E. Baumgardner and V’yacheslav Akkerman
Energies 2023, 16(18), 6752; https://doi.org/10.3390/en16186752 - 21 Sep 2023
Cited by 5 | Viewed by 1551
Abstract
Understanding and improving the performance of miniature devices powered by micro-combustion have been the focus of continued attention of researchers recently. The goal of the present work is to investigate the behavior of premixed methane–air combustion in a quartz microreactor with an externally [...] Read more.
Understanding and improving the performance of miniature devices powered by micro-combustion have been the focus of continued attention of researchers recently. The goal of the present work is to investigate the behavior of premixed methane–air combustion in a quartz microreactor with an externally controlled wall temperature. Specifically, the impacts of the flow inlet velocity, the equivalence ratio, and the microreactor channel size are examined. This study is conducted by means of computational simulations, and the results are validated against prior experimental data, as well as by other similar studies in the literature. Utilizing simulation results with detailed chemistry, the present work provides more in-depth insight into a variety of phenomena, such as ignition, flame propagation, flames with repetitive extinctions and ignitions (FREI), and flame stabilization. In particular, the ignition, the flame span, and the FREI-related characteristics are scrutinized to understand the underlying physics of the flame stability/instability modes. It is shown that the flames appear stable at higher inlet velocities, while the FREI mode is detected at a lower inlet velocity, depending on the equivalence ratio and the channel size. The findings also explain how different operating conditions impact the flame characteristics in both stability modes. Full article
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20 pages, 751 KiB  
Hypothesis
Spurious Autobiographical Memory of Psychosis: A Mechanistic Hypothesis for the Resolution, Persistence, and Recurrence of Positive Symptoms in Psychotic Disorders
by Eric Y. H. Chen, Stephanie M. Y. Wong, Eric Y. H. Tang, Lauren K. S. Lei, Yi-nam Suen and Christy L. M. Hui
Brain Sci. 2023, 13(7), 1069; https://doi.org/10.3390/brainsci13071069 - 13 Jul 2023
Cited by 2 | Viewed by 3603
Abstract
Psychotic disorders are complex disorders with multiple etiologies. While increased dopamine synthesis capacity has been proposed to underlie psychotic episodes, dopamine-independent processes are also involved (less responsive to dopamine receptor-blocking medications). The underlying mechanism(s) of the reduction in antipsychotic responsiveness over time, especially [...] Read more.
Psychotic disorders are complex disorders with multiple etiologies. While increased dopamine synthesis capacity has been proposed to underlie psychotic episodes, dopamine-independent processes are also involved (less responsive to dopamine receptor-blocking medications). The underlying mechanism(s) of the reduction in antipsychotic responsiveness over time, especially after repeated relapses, remain unclear. Despite the consistent evidence of dopamine overactivity and hippocampal volume loss in schizophrenia, few accounts have been provided based on the interactive effect of dopamine on hippocampal synapse plasticity mediating autobiographical memory processes. The present hypothesis builds upon previous works showing the potential effects of dopamine overactivity on hippocampal-mediated neuroplasticity underlying autobiographical memory, alongside known patterns of autobiographical memory dysfunction in psychosis. We propose that spurious autobiographical memory of psychosis (SAMP) produced during active psychosis may be a key mechanism mediating relapses and treatment non-responsiveness. In a hyperdopaminergic state, SAMP is expected to be generated at an increased rate during active psychosis. Similar to other memories, it will undergo assimilation, accommodation, and extinction processes. However, if SAMP fails to integrate with existing memory, a discontinuity in autobiographical memory may result. Inadequate exposure to normalizing experiences and hyposalience due to overmedication or negative symptoms may also impede the resolution of SAMP. Residual SAMP is hypothesized to increase the propensity for relapse and treatment non-responsiveness. Based on recent findings on the role of dopamine in facilitating hippocampal synapse plasticity and autobiographical memory formation, the SAMP hypothesis is consistent with clinical observations of DUP effects, including the repetition of contents in psychotic relapses as well as the emergence of treatment non-responsiveness after repeated relapses. Clinical implications of the hypothesis highlight the importance of minimizing active psychosis, integrating psychosis memory, avoiding over-medication, and fostering normalizing experiences. Full article
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28 pages, 20530 KiB  
Article
Simulation of Compact Spaceborne Lidar with High-Repetition-Rate Laser for Cloud and Aerosol Detection under Different Atmospheric Conditions
by Jie Ji, Chenbo Xie, Kunming Xing, Bangxin Wang, Jianfeng Chen, Liangliang Cheng and Xu Deng
Remote Sens. 2023, 15(12), 3046; https://doi.org/10.3390/rs15123046 - 10 Jun 2023
Cited by 3 | Viewed by 2323
Abstract
To provide references for the design of the lab’s upcoming prototype of the compact spaceborne lidar with a high-repetition-rate laser (CSLHRL), in this paper, the detection signal of spaceborne lidar was simulated by the measured signal of ground-based lidar, and then, the detection [...] Read more.
To provide references for the design of the lab’s upcoming prototype of the compact spaceborne lidar with a high-repetition-rate laser (CSLHRL), in this paper, the detection signal of spaceborne lidar was simulated by the measured signal of ground-based lidar, and then, the detection capability of spaceborne lidar under different atmospheric conditions was evaluated by means of the signal-to-noise ratio (SNR), volume depolarization ratio (VDR) and attenuated color ratio (ACR). Firstly, the Fernald method was used to invert the optical parameters of cloud and aerosol with the measured signal of ground-based lidar. Secondly, the effective signal of the spaceborne lidar was simulated according to the known atmospheric optical parameters and the parameters of the spaceborne lidar system. Finally, by changing the cumulative laser pulse number and atmospheric conditions, a simulation was carried out to further evaluate the detection performance of the spaceborne lidar, and some suggestions for the development of the system are given. The experimental results showed that the cloud layer and aerosol layer with an extinction coefficient above 0.3 km−1 could be easily obtained when the laser cumulative pulse number was 1000 and the vertical resolution was 15 m at night; the identification of moderate pollution aerosols and thick clouds could be easily identified in the daytime when the laser cumulative pulse number was 10,000 and the vertical resolution was 120 m. Full article
(This article belongs to the Special Issue Satellite and In Situ Observations of Air Pollution)
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