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14 pages, 3285 KiB  
Article
Design of Interface ASIC with Power-Saving Switches for Capacitive Accelerometers
by Juncheng Cai, Yongbin Cai, Xiangyu Li, Shanshan Wang, Xiaowei Zhang, Xinpeng Di and Pengjun Wang
Micromachines 2025, 16(1), 96; https://doi.org/10.3390/mi16010096 - 15 Jan 2025
Viewed by 538
Abstract
High-precision, low-power MEMS accelerometers are extensively utilized across civilian applications. Closed-loop accelerometers employing switched-capacitor (SC) circuit topologies offer notable advantages, including low power consumption, high signal-to-noise ratio (SNR), and excellent linearity. Addressing the critical demand for high-precision, low-power MEMS accelerometers in modern geophones, [...] Read more.
High-precision, low-power MEMS accelerometers are extensively utilized across civilian applications. Closed-loop accelerometers employing switched-capacitor (SC) circuit topologies offer notable advantages, including low power consumption, high signal-to-noise ratio (SNR), and excellent linearity. Addressing the critical demand for high-precision, low-power MEMS accelerometers in modern geophones, this work focuses on the design and implementation of closed-loop interface ASICs (Application-Specific Integrated Circuits). The proposed interface circuit, based on switched-capacitor modulation technology, incorporates a low-noise charge amplifier, sample-and-hold circuit, integrator, and clock divider circuit. To minimize average power consumption, a switched operational amplifier (op-amp) technique is adopted, which temporarily disconnects idle op-amps from the power supply. Additionally, a class-AB output stage is employed to enhance the dynamic range of the circuit. The design was realized using a standard 0.35 μm CMOS process, culminating in the completion of layout design and small-scale engineering fabrication. The performance of the MEMS accelerometers was evaluated under a 3.3 V power supply, achieving a power consumption of 3.3 mW, an accelerometer noise density below 1 μg/√Hz, a sensitivity of 1.65 V/g, a measurement range of ±1 g, a nonlinearity of 0.15%, a bandwidth of 300 Hz, and a bias stability of approximately 36 μg. These results demonstrate the efficacy of the proposed design in meeting the stringent requirements of high-precision MEMS accelerometer applications. Full article
(This article belongs to the Special Issue MEMS Inertial Device, 2nd Edition)
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11 pages, 1863 KiB  
Article
Highly Precise Time Compensation Algorithm for Synchronous Communication System Based on Least Squares
by Jin Su, Changshui Li, Qingbo Liu, Sheng Zhao and Xiangyu Wang
Viewed by 444
Abstract
Time synchronization is an important technology in synchronous communication systems to ensure the accuracy of data transmission. Precise time synchronization allows the receiver to correctly interpret the signal at the correct moment. However, as communication rates increase and application scenarios diversify, pulse signal [...] Read more.
Time synchronization is an important technology in synchronous communication systems to ensure the accuracy of data transmission. Precise time synchronization allows the receiver to correctly interpret the signal at the correct moment. However, as communication rates increase and application scenarios diversify, pulse signal reception quality is often affected by factors such as noise interference and clock stability. In order to address these challenges, we propose a pulse signal recovery method utilizing the least squares algorithm to complete time compensation. By fitting and optimizing the received signal, we can obtain estimated values that closely approximate the actual time, thereby achieving enhanced precision in time synchronization. The results demonstrate that this method effectively reduces estimation errors, improving the system’s time synchronization accuracy to the ns level. This method not only provides an effective solution for enhancing time synchronization precision but also lays the foundation for time synchronization performance in the future. Full article
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28 pages, 13265 KiB  
Article
TH301 Emerges as a Novel Anti-Oncogenic Agent for Human Pancreatic Cancer Cells: The Dispensable Roles of p53, CRY2 and BMAL1 in TH301-Induced CDKN1A/p21CIP1/WAF1 Upregulation
by Danae Farmakis, Dimitrios J. Stravopodis and Anastasia Prombona
Int. J. Mol. Sci. 2025, 26(1), 178; https://doi.org/10.3390/ijms26010178 - 28 Dec 2024
Viewed by 748
Abstract
Background: Pancreatic Ductal Adeno-Carcinoma (PDAC) is a highly aggressive cancer, with limited treatment options. Disruption of the circadian clock, which regulates key cellular processes, has been implicated in PDAC initiation and progression. Hence, targeting circadian clock components may offer new therapeutic opportunities [...] Read more.
Background: Pancreatic Ductal Adeno-Carcinoma (PDAC) is a highly aggressive cancer, with limited treatment options. Disruption of the circadian clock, which regulates key cellular processes, has been implicated in PDAC initiation and progression. Hence, targeting circadian clock components may offer new therapeutic opportunities for the disease. This study investigates the cytopathic effects of TH301, a novel CRY2 stabilizer, on PDAC cells, aiming to evaluate its potential as a novel therapeutic agent. Methods: PDAC cell lines (AsPC-1, BxPC-3 and PANC-1) were treated with TH301, and cell viability, cell cycle progression, apoptosis, autophagy, circadian gene, and protein expression profiles were analyzed, using MTT assay, flow cytometry, Western blotting, and RT-qPCR technologies. Results: TH301 proved to significantly decrease cell viability and to induce cell cycle arrest at the G1-phase across all PDAC cell lines herein examined, especially the AsPC-1 and BxPC-3 ones. It caused dose-dependent apoptosis and autophagy, and it synergized with Chloroquine and Oxaliplatin to enhance anti-oncogenicity. The remarkable induction of p21 by TH301 was shown to follow clock- and p53-independent patterns, thereby indicating the critical engagement of alternative mechanisms. Conclusions: TH301 demonstrates significant anti-cancer activities in PDAC cells, thus serving as a promising new therapeutic agent, which can also synergize with approved treatment schemes by targeting pathways beyond circadian clock regulation. Altogether, TH301 likely opens new therapeutic windows for the successful management of pancreatic cancer in clinical practice. Full article
(This article belongs to the Collection Feature Papers in Molecular Oncology)
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14 pages, 2501 KiB  
Article
Urolithin A Modulates PER2 Degradation via SIRT1 and Enhances the Amplitude of Circadian Clocks in Human Senescent Cells
by Rassul Kuatov, Jiro Takano, Hideyuki Arie, Masaru Kominami, Norifumi Tateishi, Ken-ichi Wakabayashi, Daisuke Takemoto, Takayuki Izumo, Yoshihiro Nakao, Wataru Nakamura, Kazuyuki Shinohara and Yasukazu Nakahata
Nutrients 2025, 17(1), 20; https://doi.org/10.3390/nu17010020 - 25 Dec 2024
Viewed by 700
Abstract
Background/Objectives: Circadian clocks are endogenous systems that regulate numerous biological, physiological, and behavioral events in living organisms. Aging attenuates the precision and robustness of circadian clocks, leading to prolonged and dampened circadian gene oscillation rhythms and amplitudes. This study investigated the effects of [...] Read more.
Background/Objectives: Circadian clocks are endogenous systems that regulate numerous biological, physiological, and behavioral events in living organisms. Aging attenuates the precision and robustness of circadian clocks, leading to prolonged and dampened circadian gene oscillation rhythms and amplitudes. This study investigated the effects of food-derived polyphenols such as ellagic acid and its metabolites (urolithin A, B, and C) on the aging clock at the cellular level using senescent human fibroblast cells, TIG-3 cells. Methods: Lentivirus-infected TIG-3 cells expressing Bmal1-luciferase were used for real-time luciferase monitoring assays. Results: We revealed that urolithins boosted the amplitude of circadian gene oscillations at different potentials; urolithin A (UA) amplified the best. Furthermore, we discovered that UA unstabilizes PER2 protein while stabilizing SIRT1 protein, which provably enhances BMAL1 oscillation. Conclusions: The findings suggest that urolithins, particularly UA, have the potential to modulate the aging clock and may serve as therapeutic nutraceuticals for age-related disorders associated with circadian dysfunction. Full article
(This article belongs to the Section Nutrition and Public Health)
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20 pages, 9084 KiB  
Article
The Investigation of Global Real-Time ZTD Estimation from GPS/Galileo PPP Based on Galileo High Accuracy Service
by Xin Chen, Xuhai Yang, Yulong Ge, Yanlong Liu and Hui Lei
Remote Sens. 2025, 17(1), 11; https://doi.org/10.3390/rs17010011 - 24 Dec 2024
Viewed by 476
Abstract
Utilizing real-time precise point positioning (PPP) technology is an effective approach for obtaining high-precision zenith tropospheric delay (ZTD). Without relying on the terrestrial internet, Galileo high accuracy service (HAS) can provide precise orbit and precise clock products for the world. A thorough assessment [...] Read more.
Utilizing real-time precise point positioning (PPP) technology is an effective approach for obtaining high-precision zenith tropospheric delay (ZTD). Without relying on the terrestrial internet, Galileo high accuracy service (HAS) can provide precise orbit and precise clock products for the world. A thorough assessment of the ZTD accuracy of real-time PPP calculations based on Galileo HAS products in global regions is necessary to promote its application in the field of global navigation satellite system (GNSS) meteorology. The observation data of HAS from 1 to 7 September 2023 were selected for the experiment. Firstly, the accuracy of satellite orbit and clock products of the HAS GPS and HAS Galileo system are evaluated. Then, real-time PPP positioning accuracy within and outside the HAS service area is analyzed. Finally, 104 IGS stations in the world are selected to analyze the ZTD accuracy of real-time PPP calculations based on Galileo HAS products. The experimental results show that during the test period, the RMSE values of the satellite orbit products of the HAS GPS in the radial, along, and cross directions were 4.57 cm, 10.62 cm, and 7.56 cm, respectively. The HAS Galileo RMSE values were 2.81 cm, 8.02 cm, and 7.47 cm, respectively. The RMSE values of the clock products were 0.38 ns and 0.15 ns, respectively. At the selected stations, the real-time PPP positioning accuracies outside the HAS service area and within the service area were similar, and the correlation coefficient between HAS ZTD and IGS ZTD was above 0.90. In the global region, the average bias and RMSE values of the real-time PPP ZTD of the HAS GPS were −0.31 mm and 16.78 mm. Those of the HAS Galileo were 2.30 mm and 15.89 mm, and those of the HAS GPS/Galileo were −0.25 mm and 16.11 mm, respectively. Moreover, each system showed that the accuracy of the HAS ZTD inside the service area was better than that outside the service area. Compared with the single system, the real-time PPP ZTD continuity and stability of the dual system were better. Full article
(This article belongs to the Section Satellite Missions for Earth and Planetary Exploration)
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20 pages, 5117 KiB  
Article
Digital LDO Analysis and All-Stable High-PSR One-LSB Oscillator Design
by Utsav Vasudevan and Gabriel A. Rincón-Mora
Electronics 2024, 13(24), 5033; https://doi.org/10.3390/electronics13245033 - 21 Dec 2024
Viewed by 547
Abstract
Digital low-dropout (LDO) regulators are popular in research today as compact power supply solutions. This paper provides a unique approach to analyze digital LDO feedback mechanics and stability, to reduce voltage ripple and extend operating speed over the state-of-the-art. A novel error-subtracting counter [...] Read more.
Digital low-dropout (LDO) regulators are popular in research today as compact power supply solutions. This paper provides a unique approach to analyze digital LDO feedback mechanics and stability, to reduce voltage ripple and extend operating speed over the state-of-the-art. A novel error-subtracting counter is proposed to exponentially improve the response time of any digital LDO, to keep the loop stable outside the typical operating limits, and to increase power-supply rejection (PSR). This leverages the fact that digital LDOs are fundamentally one-bit relaxation oscillators in steady-state. Theory and simulations show how the analog-to-digital (ADC) and digital-to-analog converters (DAC) in these systems affect stability. When compromised, a digital LDO produces uncontrolled sub-clock oscillations at the output that the proposed error-subtracting counter removes. Full article
(This article belongs to the Special Issue Modern Circuits and Systems Technologies (MOCAST 2024))
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21 pages, 1015 KiB  
Review
Chronobiology in Paediatric Neurological and Neuropsychiatric Disorders: Harmonizing Care with Biological Clocks
by Gabriele Giannotta, Marta Ruggiero and Antonio Trabacca
J. Clin. Med. 2024, 13(24), 7737; https://doi.org/10.3390/jcm13247737 - 18 Dec 2024
Viewed by 911
Abstract
Background: Chronobiology has gained attention in the context of paediatric neurological and neuropsychiatric disorders, including migraine, epilepsy, autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and post-traumatic stress disorder (PTSD). Disruptions in circadian rhythms are associated with key symptoms such as sleep disturbances, [...] Read more.
Background: Chronobiology has gained attention in the context of paediatric neurological and neuropsychiatric disorders, including migraine, epilepsy, autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and post-traumatic stress disorder (PTSD). Disruptions in circadian rhythms are associated with key symptoms such as sleep disturbances, mood dysregulation, and cognitive impairments, suggesting a potential for chronobiology-based therapeutic approaches. Methods: This narrative review employs a systematic approach to identify relevant studies through searches of three major scientific databases, NCBI/PubMed, ScienceDirect, and Scopus, up to July 2024. We used a combination of broad and condition-specific keywords, such as “chronobiology”, “biorhythm”, “pediatric”, “epilepsy”, “ADHD”, and “ASD”, among others. Articles in English that focused on clinical features, treatments, or outcomes related to circadian rhythms in paediatric populations were included, while non-peer-reviewed articles and studies lacking original data were excluded. Rayyan software was used for article screening, removing duplicates, and facilitating consensus among independent reviewers. Results: A total of 87 studies were included in the analysis. Findings reveal a consistent pattern of circadian rhythm disruptions across the disorders examined. Specifically, dysregulation of melatonin and cortisol secretion is observed in children with ASD, ADHD, and PTSD, with altered circadian timing contributing to sleep disturbances and mood swings. Alterations in core clock genes (CLOCK, BMAL1, PER, and CRY) were also noted in children with epilepsy, which was linked to seizure frequency and timing. Chronotherapy approaches showed promise in managing these disruptions: melatonin supplementation improved sleep quality and reduced ADHD symptoms in some children, while light therapy proved effective in stabilizing sleep–wake cycles in ASD and ADHD patients. Additionally, behaviour-based interventions, such as the Early Start Denver Model, showed success in improving circadian alignment in children with ASD. Conclusions: This review highlights the significant role of circadian rhythm disruptions in paediatric neurological and neuropsychiatric disorders, with direct implications for treatment. Chronobiology-based interventions, such as melatonin therapy, light exposure, and individualized behavioural therapies, offer potential for improving symptomatology and overall functioning. The integration of chronotherapy into clinical practice could provide a paradigm shift from symptom management to more targeted, rhythm-based treatments. Future research should focus on understanding the molecular mechanisms behind circadian disruptions in these disorders and exploring personalized chronotherapeutic approaches tailored to individual circadian patterns. Full article
(This article belongs to the Section Clinical Pediatrics)
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11 pages, 4652 KiB  
Article
Improving 795 nm Single-Frequency Laser’s Frequency Stability by Means of the Bright-State Spectroscopy with Rubidium Vapor Cell
by Junye Zhao, Yongbiao Yang, Lulu Zhang, Yang Li and Junmin Wang
Photonics 2024, 11(12), 1165; https://doi.org/10.3390/photonics11121165 - 11 Dec 2024
Viewed by 572
Abstract
The utilization of atomic or molecular spectroscopy for frequency locking of single-frequency laser to improve laser frequency stability plays an important role in the experimental investigation of optically pumped atomic magnetometers, atomic clocks, laser cooling and trapping of atoms, etc. We have experimentally [...] Read more.
The utilization of atomic or molecular spectroscopy for frequency locking of single-frequency laser to improve laser frequency stability plays an important role in the experimental investigation of optically pumped atomic magnetometers, atomic clocks, laser cooling and trapping of atoms, etc. We have experimentally demonstrated a technique for frequency stabilization of a single-frequency laser employing the bright state spectroscopy (BSS) with a rubidium atomic vapor cell. By utilizing the counter-propagating dual-frequency 795 nm laser beams with mutually orthogonal linear polarization and a frequency difference of 6.834 GHz, which is equal to the hyperfine splitting of rubidium-87 ground state 5S1/2, an absorption-enhanced signal with narrow linewidth at the center of Doppler-broadened transmission spectroscopy is observed when continuous scanning the laser frequency over rubidium-87 D1 transition. This is the so-called BSS. Amplitude of the absorption-enhanced signal in the BSS is much larger compared with the conventional saturation absorption spectroscopy (SAS). The relationship between linewidth and amplitude of the BSS signal and laser beam intensity has been investigated. This high-contrast absorption-enhanced BSS signal has been employed for the laser frequency stabilization. The experimental results show that the frequency stability is 4.4×1011 with an integration time of 40 s, near one order of magnitude better than that for using the SAS. Full article
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16 pages, 1429 KiB  
Article
Multidrug-Resistant Klebsiella pneumoniae Strains in a Hospital: Phylogenetic Analysis to Investigate Local Epidemiology
by Maria Vittoria Ristori, Fabio Scarpa, Daria Sanna, Marco Casu, Nicola Petrosillo, Umile Giuseppe Longo, De Florio Lucia, Silvia Spoto, Rosa Maria Chiantia, Alessandro Caserta, Raffaella Rosy Vescio, Flavio Davini, Lucrezia Bani, Elisabetta Riva, Massimo Ciccozzi and Silvia Angeletti
Microorganisms 2024, 12(12), 2541; https://doi.org/10.3390/microorganisms12122541 - 10 Dec 2024
Viewed by 820
Abstract
Multidrug-resistant Klebsiella pneumoniae is a significant healthcare challenge that particularly affects vulnerable patients through opportunistic nosocomial infections. Surveillance is crucial for monitoring the prevalence of these infections. Eighty-four KPC K. pneumoniae strains (2019–2022) were collected from patients admitted in Fondazione Policlinico Universitario Campus [...] Read more.
Multidrug-resistant Klebsiella pneumoniae is a significant healthcare challenge that particularly affects vulnerable patients through opportunistic nosocomial infections. Surveillance is crucial for monitoring the prevalence of these infections. Eighty-four KPC K. pneumoniae strains (2019–2022) were collected from patients admitted in Fondazione Policlinico Universitario Campus Bio-Medico. Strains were identified by MALDI-TOF and tested for antimicrobial susceptibility, and gene amplification was performed to identify the different blaKPC variants. Phylogenetic reconstructions were carried out using Bayesian methods. Additionally, to create a Bayesian skyline plot (BSP), additional analyses were conducted, running a simulation of 100 million generations under a Bayesian skyline model along with the uncorrelated log-normal relaxed clock model. To identify potential subgroups within genetic clusters and evaluate genetic variability among sequences, principal coordinate analysis (PCoA) was performed. In total, 84 Klebsiella pneumoniae isolates were classified as multidrug-resistant (MDR), characterized by resistance to three or more antibiotic classes, including carbapenems, and testing positive for KPC gene presence, and were included in the study. The Bayesian evolutionary tree for K. pneumoniae showed strongly supported branches but no genetic structure related to sampling dates or hospital departments. Phylogenetic analysis revealing a 73-year evolutionary span of K. pneumoniae strains. PCoA analysis identified three genetic outliers from 2022 and one from 2021, indicating higher genetic distances. The Bayesian skyline plot revealed increased genetic variability peaking at the end of 2019, followed by stabilization from early 2020 onward, with no significant changes in genetic variability thereafter. Overall, the study found no genetic structure correlating with sampling date or hospital department, suggesting significant variability in pathogen introduction during the pandemic. The increase in multidrug-resistant K. pneumoniae was linked to the influx of severe COVID-19 cases, prolonged hospitalizations, and heightened broad-spectrum antibiotic use, which likely facilitated resistance development and transmission amidst altered infection control practices. Full article
(This article belongs to the Special Issue Antimicrobial Resistance: Challenges and Innovative Solutions)
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11 pages, 3759 KiB  
Communication
Precision and Stability of a Space Laser Ranging Technology Based on Time-Frequency Co-Transfer
by Shaobo Li, Lei Zhang, Dongjie Wang, Yuhan Hu, Mingyang Lv, Zhe Li and Yihan Li
Photonics 2024, 11(12), 1126; https://doi.org/10.3390/photonics11121126 - 28 Nov 2024
Viewed by 683
Abstract
This paper presents an innovative space laser ranging technology that utilizes time-frequency co-transfer, effectively meeting the critical demand for precision in space laser ranging applications. The aim is to achieve high-precision ranging by calculating the transfer time using a bidirectional comparison scheme for [...] Read more.
This paper presents an innovative space laser ranging technology that utilizes time-frequency co-transfer, effectively meeting the critical demand for precision in space laser ranging applications. The aim is to achieve high-precision ranging by calculating the transfer time using a bidirectional comparison scheme for clock synchronization and an active compensation technique for frequency transfer. Experimental results indicate that, over a 500 m optical path, an impressive ranging accuracy of 0.0005 m is achieved, reflecting significant improvements in precision, stability, and resistance to interference. By integrating time synchronization, frequency transfer, and free-space laser ranging into a cohesive system, this technology demonstrates substantial potential for a wide range of applications. Full article
(This article belongs to the Section Lasers, Light Sources and Sensors)
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20 pages, 7946 KiB  
Article
Neuronal Progenitors Suffer Genotoxic Stress in the Drosophila Clock Mutant per0
by Nunzia Colonna Romano, Marcella Marchetti, Anna Marangoni, Laura Leo, Diletta Retrosi, Ezio Rosato and Laura Fanti
Cells 2024, 13(23), 1944; https://doi.org/10.3390/cells13231944 - 23 Nov 2024
Viewed by 736
Abstract
The physiological role and the molecular architecture of the circadian clock in fully developed organisms are well established. Yet, we have a limited understanding of the function of the clock during ontogenesis. We have used a null mutant (per0) of [...] Read more.
The physiological role and the molecular architecture of the circadian clock in fully developed organisms are well established. Yet, we have a limited understanding of the function of the clock during ontogenesis. We have used a null mutant (per0) of the clock gene period (per) in Drosophila melanogaster to ask whether PER may play a role during normal brain development. In third-instar larvae, we have observed that the absence of functional per results in increased genotoxic stress compared to wild-type controls. We have detected increased double-strand DNA breaks in the central nervous system and chromosome aberrations in dividing neuronal precursor cells. We have demonstrated that reactive oxygen species (ROS) are causal to the genotoxic effect and that expression of PER in glia is necessary and sufficient to suppress such a phenotype. Finally, we have shown that the absence of PER may result in less condensed chromatin, which contributes to DNA damage. Full article
(This article belongs to the Section Cell Nuclei: Function, Transport and Receptors)
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24 pages, 7272 KiB  
Article
Comprehensive Analysis of BDS/GNSS Differential Code Bias and Compatibility Performance
by Yafeng Wang, Dongjie Yue, Hu Wang, Hongyang Ma, Zhiqiang Liu and Caiya Yue
Remote Sens. 2024, 16(22), 4217; https://doi.org/10.3390/rs16224217 - 12 Nov 2024
Viewed by 926
Abstract
High-precision DCBs are essential for effective multi-frequency and multi-constellation GNSS integration, especially in processing compatible signal observations. This study utilizes data from MGEX, iGMAS, and CORS stations to estimate and analyze long time series of BDS/GNSS DCBs, focusing on stability and influencing factors. [...] Read more.
High-precision DCBs are essential for effective multi-frequency and multi-constellation GNSS integration, especially in processing compatible signal observations. This study utilizes data from MGEX, iGMAS, and CORS stations to estimate and analyze long time series of BDS/GNSS DCBs, focusing on stability and influencing factors. Results indicate that DCBs for the same signal, but different channels exhibit similar ranges and trends. Among BDS DCBs, those from satellites with rubidium atomic clocks are more stable than those with hydrogen atomic clocks. An upgrade and maintenance of BDS in late 2022, reported by NABU, likely contributed to DCB jumps. BDS-compatible signal DCBs show weaker stability compared to GPS and Galileo. Variations in GNSS signal processing and receiver algorithms also impact DCB stability. Converting DCBs to OSBs and performing RMS statistics revealed that smaller differences between signals increase the susceptibility of observation equations to observation quality. Full article
(This article belongs to the Topic GNSS Measurement Technique in Aerial Navigation)
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17 pages, 4975 KiB  
Article
Research on Distributed Autonomous Timekeeping Algorithm for Low-Earth-Orbit Constellation
by Shui Yu, Jing Peng, Ming Ma, Hang Gong, Zongnan Li and Shaojie Ni
Remote Sens. 2024, 16(21), 4092; https://doi.org/10.3390/rs16214092 - 2 Nov 2024
Viewed by 1259
Abstract
The time of a satellite navigation system is primarily generated by the main control station of the ground system. Consequently, when ground stations fail, there is a risk to the continuous provision of time services to the equipment and users. Furthermore, the anticipated [...] Read more.
The time of a satellite navigation system is primarily generated by the main control station of the ground system. Consequently, when ground stations fail, there is a risk to the continuous provision of time services to the equipment and users. Furthermore, the anticipated launch of additional satellites will further strain the satellite–ground link. Next-generation satellite navigation systems will rely on time deviation measurements from inter-satellite links to independently establish and maintain a space-based time reference, enhancing the system’s reliability and robustness. The increasing number of low-Earth-orbit satellite navigation constellations provides ample resources for establishing a space-based time reference. However, this also introduces challenges, including extensive time scale computations, increased link noise, and low clock resource utilization. To address these issues, this paper proposes a Distributed Kalman Plus Weight (D-KPW) algorithm, which combines the benefits of Kalman filtering and the weighted average algorithm, balancing the performance with computational resources. Furthermore, an adaptive clock control algorithm, D-KPW (Control), is developed to account for both the short-term and long-term frequency stability of the time reference. The experimental results demonstrate that the frequency stability of the time reference established by the D-KPW (Control) algorithm reaches 7.40×1015 and 2.30×1015 for sampling intervals of 1000 s and 1,000,000 s, respectively, outperforming traditional algorithms such as ALGOS. The 20-day prediction error of the time reference is 1.55 ns. Compared to traditional algorithms such as AT1, ALGOS, Kalman, and D-KPW, the accuracy improves by 65%, 65%, 66%, and 67%, respectively. Full article
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16 pages, 2025 KiB  
Article
Pre- and Post-Operative Cognitive Assessment in Patients Undergoing Surgical Aortic Valve Replacement: Insights from the PEARL Project
by Valentina Fiolo, Enrico Giuseppe Bertoldo, Silvana Pagliuca, Sara Boveri, Sara Pugliese, Martina Anguissola, Francesca Gelpi, Beatrice Cairo, Vlasta Bari, Alberto Porta and Edward Callus
NeuroSci 2024, 5(4), 485-500; https://doi.org/10.3390/neurosci5040035 - 28 Oct 2024
Viewed by 895
Abstract
Background: Aortic valve stenosis (AVS) is a common valvular heart disease affecting millions of people worldwide. It leads to significant neurocognitive and neuropsychological impairments, impacting patients’ quality of life. Objective: The objective of this article is to identify and discuss the potential neurocognitive [...] Read more.
Background: Aortic valve stenosis (AVS) is a common valvular heart disease affecting millions of people worldwide. It leads to significant neurocognitive and neuropsychological impairments, impacting patients’ quality of life. Objective: The objective of this article is to identify and discuss the potential neurocognitive effects on patients with aortic stenosis before and after undergoing surgical aortic valve replacement (SAVR). Method: Our study involved the assessment of 64 patients undergoing aortic valve replacement (SAVR) using a neurocognitive evaluation comprising a battery of 11 different cognitive tests. These tests were designed to analyze the patients’ overall cognitive functioning, executive abilities, short- and long-term memory, and attentional performance. The tests were administered to patients before the aortic valve surgery (T0) and after the surgery (T1). From a statistical perspective, numerical variables are presented as means (±standard deviation) and medians (IQR), while categorical variables are presented as counts and percentages. Normality was assessed using the Shapiro–Wilk test. T0 and T1 scores were compared with the Wilcoxon signed rank test, with p < 0.05 considered significant. Analyses were performed using SAS version 9.4. Results: Conducted as part of a fully financed Italian Ministry of Health project (RF-2016-02361069), the study found that most patients showed normal cognitive functioning at baseline. Cognitive assessments showed that executive functions, attention, language, and semantic knowledge were within the normal range for the majority of participants. After SAVR, cognitive outcomes remained stable or improved, particularly in executive functions and language. Notably, verbal episodic memory demonstrated significant improvement, with the percentage of patients scoring within the normal range on the BSRT increasing from 73.4% at T0 to 92.2% at T1 (p < 0.0001). However, visuospatial and visuoconstructive abilities showed stability or slight decline, while attentional skills remained relatively stable. The Clock Drawing Test indicated the maintenance of cognitive functions. Conclusions: The findings of our study indicate a global stability in cognitive status among patients after undergoing SAVR, with significant improvement noted in verbal episodic memory. While other cognitive domains did not demonstrate statistically significant changes, these insights are valuable for understanding the cognitive effects of SAVR and can guide future research and clinical practice in selecting the most effective surgical and rehabilitative options for patients. Monitoring cognitive outcomes in patients undergoing aortic valve replacement surgery remains crucial. Full article
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17 pages, 1182 KiB  
Article
Synchronization of Chaotic Systems with Huygens-like Coupling
by Jonatan Pena Ramirez, Adrian Arellano-Delgado, Rodrigo Méndez-Ramírez and Hector Javier Estrada-Garcia
Mathematics 2024, 12(20), 3177; https://doi.org/10.3390/math12203177 - 11 Oct 2024
Viewed by 970
Abstract
One of the earliest reports on synchronization of inert systems dates back to the time of the Dutch scientist Christiaan Huygens, who discovered that a pair of pendulum clocks coupled through a wooden bar oscillate in harmony. A remarkable feature in Huygens’ experiment [...] Read more.
One of the earliest reports on synchronization of inert systems dates back to the time of the Dutch scientist Christiaan Huygens, who discovered that a pair of pendulum clocks coupled through a wooden bar oscillate in harmony. A remarkable feature in Huygens’ experiment is that different synchronous behaviors may be observed by just changing a parameter in the coupling. Motivated by this, in this paper, we propose a novel synchronization scheme for chaotic oscillators, in which the design of the coupling is inspired in Huygens’ experiment. It is demonstrated that the coupled oscillators may exhibit not only complete synchronization, but also mixed synchronization—some states synchronize in anti-phase whereas other states synchronize in-phase—depending on a single parameter of the coupling. Additionally, the stability of the synchronous solution is investigated by using the master stability function approach and the largest transverse Lyapunov exponent. The Lorenz system is considered as particular application example, and the performance of the proposed synchronization scheme is illustrated with computer simulations and validated by means of experiments using electronic circuits. Full article
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