Signal Values Research Articles

On the partial volume effect in magnetic particle imaging

Objective.Magnetic particle imaging (MPI) is an emerging tomographic 'hot spot' imaging modality with potential to visualize superparamagnetic iron oxide nanoparticle tracer distributions with high sensitivity and quantitative accuracy. MPI shares many similarities with positron emission tomography (PET), where the partial volume effect (PVE) can result in signal under- and over-quantification due to spill-over of signal arising from limited resolution. While the PVE has been alluded to in the MPI literature it has not been previously studied nor characterized. The objective of this study was to systematically characterize this PVE in MPI.Approach.This contribution characterizes the PVE using models of varying size and shape filled with a uniform concentration of tracer. The effect of object size on signal distribution was analyzed after application of a new image post-processing filter.Main results.As object size increased, signal distribution increased to a maximum signal value independent of object geometry and proportional to tracer concentration. Furthermore, for small objects with characteristic dimensions below the resolution of the tracer at the scanning conditions used, signal suppression was observed. These results are consistent with foundational observations of PVE in PET, suggesting that approaches to overcome the PVE in PET may be applicable to MPI.Significance.This finding has significant impact on the MPI field by demonstrating the presence of the PVE phenomenon that can directly influence imaging results.

An Envelope-to-Cycle Difference Compensation Method for eLoran Signals in Seawater Based on a Variable Step Size Least Mean Square Algorithm

The dispersion effect of seawater can cause the envelop distortion of underwater eLoran signals, which causes the envelope-to-cycle difference (ECD) to exceed the standard range. Furthermore, it results in incorrect cycle identification and significant positioning errors. However, few studies have focused on the distortion caused by the dispersion effect. In this study, we propose an accurate underwater eLoran ECD compensation method based on a variable step size least mean square (VSS-LMS) algorithm. First, a systematic modeling approach was employed to investigate the impact of dispersion effects on Loran signals. Second, the VSS-LMS algorithm was introduced to update the filter weight vector in response to discrepancies in the input signal. Finally, the input signal was subjected to an adaptive transversal filtering process, resulting in an output signal that adhered to the specifications of the ECD standard. The efficacy and superiority of the proposed algorithm were demonstrated by experimentation and simulation. When the depth of seawater exceeds 2 m, the ECD value of the original eLoran signal exceeds the standard range, precluding the possibility of cycle identification. However, when the depth of seawater reaches 4 m, the ECD of the signal compensated by the proposed algorithm adaptively compensates for the normal range, thereby enabling the accurate recognition of cycles.

Pre-entry experience, knowledge inheritance, and entrepreneurial resource mobilization

Abstract We study the conditions under which founders’ pre-entry experience in the industry affects the prospects of new ventures mobilizing financial resources. Drawing on signaling theory, we theorize that the signal value of pre-entry experience is contingent on the extent to which new ventures leverage such experience as well as the environmental context in which they operate. Specifically, we argue that knowledge linkages to founders’ former employer increase the clarity of the pre-entry experience signal. We further posit that this clarified pre-entry experience signal is more valuable in competitive environments. We investigate these effects by focusing on the time to first VC funding for startups in the US semiconductor industry. We show that (1) knowledge linkages to the founders’ previous employer accentuate the effect of pre-entry experience by further shortening the time to VC funding and (2) this shortening in time is more significant when the industry clustering is high.

Digital adaptive control with pulse width modulation of signals

The paper presented research results of a digital control system for a dynamic plant with pulse-width modulation (PWM) of control impacts. As the control PWM signal is taken the pulse duty cycle, is calculated on each current cycle of the sample from the measured values. A control algorithm is proposed based on a hybrid application of the linear-quadratic optimization procedure and the theory of observers of minimal complexity. To ensure execution that the conditions of Astatism are met, the dynamic model of the plant is supplemented with a discrete integrator. The proposed approach makes it possible to reduce hardware costs and increase the robustness of the control system due to the exclusion of operations for digital–analogue transformations of signals. The proposed algorithm for digital control of a dynamic plant with varying duty cycle values of the PWM signal shows that the PWM model turned out to be linear and practically inertia less, which makes it easy to take into account the modulator model, which significantly simplifies the solution of the problem of synthesizing a control system for a dynamic plant. The possibility of receiving a high-quality modulated control signal allows for significant suppression of signal pulsations and high control accuracy.

Comparative Analysis of Denoising Techniques for Optimizing EEG Signal Processing

Electroencephalogram (EEG) is a non-invasive technology that is widely used to record the electrical activity of the brain. However, often the EEG signal is contaminated by noise, including ocular artefacts and muscle activity, which can interfere with accurate analysis and interpretation. This research aims to improve the quality of EEG signals related to concentration by comparing the effectiveness of two denoising methods, namely Independent Component Analysis (ICA) and Principal Component Analysis (PCA). Using commercial EEG headsets, this study recorded Alpha, Beta, Delta, and Theta signals from 20 participants while they performed tasks that required concentration. Evaluation of the effectiveness of the denoising technique is carried out by focusing on changes in standard deviation and calculating the Percentage Residual Difference (PRD) value of the EEG signal before and after denoising. The results show that ICA provides better denoising performance than PCA, as reflected by a significant reduction in standard deviation and a lower PRD value. These results indicate that the ICA method can effectively reduce noise and preserve important information from the original signal.

One-Step Synthesis of Carboxylated Polyethylene Glycol-Modified Polystyrene Microspheres and Their Application in the Luminescent Oxygen Channel Immunoassay.

As one of the key diagnostic methods for detecting biomarkers and antigen-antibody interactions, the luminescent oxygen channel immunoassay (LOCI) has been widely applied in bioanalysis and other fields. In the context of LOCI, the performance of the prepared donor polystyrene (PS) microspheres significantly impacts the detection signal values. In this study, an attempt was made to synthesize PS microspheres via one-step polymerization of styrene with an amphiphilic monomer (PEOOH), followed by swelling the silicon phthalocyanine photosensitizer into the PS microspheres, resulting in the functionalization of the PS microspheres with polyethylene glycol segments. The chemical stability and water solubility of polyethylene glycol (PEG) make it a versatile surface modification material while also inhibiting nonspecific protein adsorption. Results indicated that with increasing PEOOH content, the nonspecific protein adsorption of the resulting PS microspheres reduced, with the adsorption ability for BSA decreasing from 26.8 to 1.3 mg/g, approximately decreasing by 95.2%. Furthermore, the results demonstrated that PS microspheres prepared with 6% PEOOH exhibited a maximum signal-to-noise ratio (S/N) (approximately 28.7), nearly 14 times higher than PS microspheres without PEOOH (approximately 2.1). The analytical performance of the system for detecting staphylococcal enterotoxin B (SEB) revealed a detection limit of 0.1 ng/mL and a linear concentration range of 0.1 to 50 ng/mL for the donor PS microspheres (6% PEOOH). The synthesized donor PS microspheres exhibit a uniform particle size and stable signals, making them effective LOCI microcarriers. These properties facilitate a deeper understanding of molecular interactions and signal transduction mechanisms within biological systems.

Hepatobiliary Adverse Events Associated With the KRAS p.G12C Inhibitor Sotorasib.

The p.G12C mutation in KRAS is commonly found in many cancers and was previously untreatable until drugs like sotorasib were developed. However, up to 15% of patients treated with sotorasib have experienced hepatobiliary adverse events. To investigate whether these side effects are more common among sotorasib users, a pharmacovigilance study is necessary. This study used the FDA adverse event reporting system (FAERS) database, a publicly available repository of reported drug adverse events, and AERSMine, an open-access pharmacovigilance tool, to investigate these adverse events. A total of 428 hepatobiliary adverse events were linked to sotorasib. Hepatic cytolysis had the highest reported relative risk at 26.541 and a safety signal of 4.726. Elevated liver and biliary enzymes such as AST, ALT, ALP, and GGT were commonly observed, but with lower reported relative risk and safety signal values, which supports previous real-world reports. These findings highlight the hepatobiliary risks associated with sotorasib and underscore the importance of closely monitoring liver function in patients who are using the medication. This is particularly crucial for patients with hepatobiliary cancers, as disease progression and adverse events could be misinterpreted.

Polydopamine-encapsulated carbon dots to boost analytical performance for microplastics detection in fluorescence mode.

Akind of sulfur-doped carbon dots was preparedwhich were encapsulated with polydopamine (S-CDs@PDA) that has fluorescence response on polyethylene (PE) microplastics (MPs). Modified membranes were constructed using S-CDs@PDA for MP detection. Through heating and vacuum filtration process, yellow emission from the modified membrane appeared because of the combination between S-CDs@PDA and PE MPs. Notably, the fluorescence signal value of PE MPs detected by S-CDs@PDA-modified membrane was 21.3% higher than that of unmodifiedS-CDs membrane, and the detection efficiency was 8% higher than that of S-CDs membrane. The minimum detection limit for modified membranes was 4mg. Due to the good adhesion of polydopamine (PDA), S-CDs@PDA-modified membrane was more easily adhered to PE MPs, showing its excellent detection ability. The rapid quantitative detection of PE MPs in 10min was realized with a linear equation of y = 3081x + 3686.1 in a linear range of 4-14mg. Such modified membrane exhibited excellent anti-photobleaching using continuous 365-nm excitation and its sensing performance was further confirmed in sea and river water samples. S-CDs@PDA could detect solid MP powders as well as MPs dispersed in liquids. The detection method constructed with a modified glass fiber filter membrane enables rapid identification and quantitative detection of PE MPs without relying on large-scale instrumentation. This study provided research ideas for fluorescent tracing of PE MPs and paved the way for quantitative detection of micron-sized plastics with smaller particle sizes.

Comparison and performance optimization of two absolute circuit designs based on Multisim

Digital circuits are crucial in today's technology, underpinning infrastructure such as computing, communicating, and intelligent devices. Its high efficiency, accuracy and programmable capability drive the development of information processing, data transmission and automation systems. The application of digital circuits has promoted innovation in artificial intelligence, the Internet of Things and other fields, providing strong support for the intelligence and interconnection of modern society. The absolute value circuit is discussed in this paper. The absolute value circuit is implemented for converting the negative value of the input signal to a positive value, ensuring that the output signal is always non-negative. Its significance is to handle application scenarios that require non-negative values, such as signal processing, audio amplification, and sensor output. Through the absolute value circuit, negative value can avoid the negative effect on the subsequent circuit, and improve the stability and accuracy of the system. This paper first introduces all the gates used in the circuit, points out the functions of each gate circuit, and then puts forward two absolute value circuit designs, explaining their working principles, differences and advantages and disadvantages. Then the minimum delay is analyzed by the critical path logic and the sizes of each logic gate is given. Then the supply voltage is optimized after selecting the design with the smallest delay to reduce energy consumption.

Study on Highly Sensitive Capacitive Pressure Sensor Based on Silk Fibroin-Lignin Nanoparticles Hydrogel.

Silk fibroin (SF) hydrogel has been proven to have excellent applications in the field of pressure sensors, but its sensing performance still needs improvement. A flexible hydrogel prepared from natural macromolecular materials was developed, and lignin nanoparticles (LNPs) were introduced during the preparation of the SF hydrogel. When LNPs account for 3% of SF, the sensing unit of the SF-LNPs3% hydrogel exhibits high stress sensitivity (1.32 kPa-1), fast response speed (<0.1 s), and superior cycle stability (≥8000 cycles). The sensor can detect human motion information, such as finger bending, elbow bending, and pulse signals. When worn at the vocal cord position, it can detect the peak value of the characteristic signal during the wearer speaks. This work demonstrates that the SF-LNPs3% hydrogel has high sensitivity and shows great potential in the field of pressure sensors.

Hepatotoxicity of statins: a real-world study based on the US Food and Drug Administration Adverse Event Reporting System database.

Statins, as an important class of lipid-lowering drugs, play a key role in the prevention and treatment of cardiovascular diseases. However, with their widespread use in clinical practice, some adverse events have gradually emerged. In particular, the hepatotoxicity associated with statins use has become one of the clinical concerns that require sufficient attention. In this study, we conducted a comprehensive and detailed analysis of the hepatotoxicity of statins based on the data of the US Food and Drug Administration Adverse Event Reporting System database from the first quarter (Q1) of 2004 to the Q1 of 2024 and used Reporting Odds Ratios and Empirical Bayes Geometric Mean to mine the signal of adverse events. In this study, hepatic disorder related seven statins all exhibited positive signals. Through signal mining, we identified a total of 14,511 cases of adverse events associated with hepatic disorder caused by these statin drugs, with atorvastatin, simvastatin, and rosuvastatin occurring at a higher rate. A total of 148 positive signals related to adverse events of hepatic disorder were captured. Autoimmune hepatitis and drug-induced liver injury both presented positive signals across multiple statin drugs. Notably, atorvastatin had the most significant signal strength in cholestatic pruritus and bilirubin conjugation abnormal. Fluvastatin also showed notable signal strength in autoimmune hepatitis, while simvastatin had a relatively weaker signal strength for hepatic enzyme increased. This study discovered specific adverse event signal values, revealing potential hepatotoxic risks associated with the use of statin drugs. The results provide an important reference for the safe clinical use of drugs, help to improve the understanding of the safety of statins, and also provide a scientific basis for clinicians to make more accurate and safe decisions when making treatment plans.

Attempt to Improve MIP Image of Cerebrovascular MRA by Subtraction Method: Efficient Acquisition of Mask Images Using Segmented TOF and Compressed Sensing

The aim of this study was to investigate imaging conditions that allow for the rapid acquisition of mask images used in the subtraction method, one of the depiction improvement methods for brain magnetic resonance angiography, by employing compressed sensing (CS) combined with segmented time-of-flight (TOF). The experiment was performed on healthy volunteers using 3.0T-MRI. We examined the blood flow signal suppression effects in arteries and veins at different numbers of segments. We determined the flip angle at which the signal value of fat in the mask image became equivalent to that in the angio image. We visually assessed the impact of mask images with varying CS factors on subtraction images and determined the optimal CS factor. Effective blood flow signal suppression in arteries and veins was achieved with segment numbers of 12 or fewer, and a flip angle of 18° resulted in equivalent fat signal values. Even with a CS factor set to its maximum value of 12, no degradation in image quality was observed in the maximum intensity projection images. Using segmented TOF with CS, optimal imaging conditions for acquiring mask images for the subtraction method were determined to be segment number 9, flip angle 18°, and CS factor 12.

How Does Virtual Reality Exposure Treatment Change the Brain Function of Acrophobia Patients? A Randomized Controlled Trial

Background: Virtual reality exposure therapy (VRET), an innovative form of exposure therapy (ET), has been demonstrated to be effective in treating acrophobia. However, its neural mechanisms of action and how it differs from traditional imaginal exposure therapy (IET) remain unclear. This study utilized resting‐state functional magnetic resonance imaging (fMRI) to investigate the effects of VRET on brain activity in acrophobic patients and to explore the potential mechanisms underlying its therapeutic action.Method: Fifty patients with acrophobia were randomly assigned to either an experimental group (25 patients) or a control group (25 patients) based on different treatments. The experimental group received VRET, while the control group received conventional IET. A mixed‐design repeated‐measures analysis of variance (ANOVA) was performed on the whole brain to identify brain regions affected by the intervention. Both groups of patients underwent treatment twice a week for 3 weeks. fMRI scans were performed for all patients at baseline and after treatment to facilitate a comparison of clinical effects at the end of the treatment period. The degree centrality (DC) values of the blood oxygenation level dependent signals across the entire brain were analyzed. A mixed‐design repeated‐measures ANOVA was conducted on the pre‐ and post‐intervention data to identify brain regions affected by the intervention. The degree of symptom improvement was assessed using self‐report measures, including the Acrophobia Questionnaire (AQ), the Attitude Toward Heights Questionnaire, the Behavior Avoidance Test, and the 7‐item Generalized Anxiety Disorder Scale. These assessments were correlated with pre‐ and post‐intervention differences in brain activity. Additionally, a functional connectivity (FC) analysis was conducted to identify any atypical connectivity patterns following the ET.Results: There was a significant positive correlation between the change in scores on the AQ and the right middle temporal gyrus (MTG) (r = 0.442, p = 0.045). After VRET, DC values in the right calcarine, MTG, cuneus, and precuneus were decreased (p &lt; 0.005), while DC values in the postcentral gyrus decreased after IET (p &lt; 0.05). Additionally, reduced FC between the right MTG and both the right medial superior frontal gyrus and the left MTG was observed in acrophobia patients following VRET. In the IET group, reduced FC between the left MTG and the left superior temporal gyrus was found (p &lt; 0.005).Conclusion: Preliminary results suggest that VRET may improve abnormal brain activity in acrophobia by modulating the activity of the default mode network and the primary visual cortex.

Algorithm for Detecting Reference Points on a Digital Electrocardiogram in Real Time

Relevance. The use of digital electrocardiographs and cardiac monitors with built-in algorithms for automatic processing, analysis and interpretation of electrocardiograms allows the doctor to effectively diagnose cardiac arrhythmias. It is known that in order to provide emergency care to a patient, the duration of arrhythmia diagnostics should not exceed several tens of seconds, which requires the emergence of new algorithms for detecting informative features indicating arrhythmia, operating in real time. The need to introduce new and effective technologies for diagnosing cardiovascular diseases is also reflected in public health development programmes.Research goal. Development and quality indicators analysis of the algorithm for reference points detection on a digital electrocardiogram, bearing informative signs for the procedure of arteries diagnosis.The methods used. The study is based on an analysis of existing approaches to the problem of reference points detection on digital electrocardiogram, as well as conducting a test of the proposed algorithms by mathematical modelling methods. The quality indicators of the algorithms defined in accordance with the principles of signal detection theory and diagnostic testing, at the junction of which the task of electrocardiogram reference point detection is located. The proposed algorithm was tested on materials of MIT-BIH Arrhythmia Database, which is widely used for verification and validation of real-time digital electrocardiogram signal processing algorithms.The results. The study proposes an algorithm for detecting reference points on a digital electrocardiogram that carry informative features for the arrhythmia diagnostic procedure. The proposed algorithm is based on digital signal filtering using a decision rule based on a three-step two-threshold principle of pre-processed electrocardiogram signal values comparison on a sliding window. An experiment on the materials of the open verified MIT-BIH Arrhythmia DB showed that the quality of the proposed algorithm for detecting reference points is higher than that of the algorithms used in modern digital electrocardiographs and cardiac monitors. The proposed algorithm based on digital signal filtering and the three-step two-threshold decision rule have elements of scientific novelty.The significance. The results of this work can be used in the development of digital heart rate monitors, cardiac devices and for automatic processing, analysis and real-time computer-assisted digital electrocardiogram signal interpretation.

Determination of carbonation rate of precipitated calcium carbonate in carbonation process based on headspace gas chromatography.

This paper reports a method for determining the carbonation rate (CR) of precipitated calcium carbonate (PCC) during carbonation process based on headspace gas chromatography technique. The method was carried out by simultaneously detecting the signal values of carbon dioxide and oxygen. Then the carbonation rate of precipitated calcium carbonate in the carbonation process can be calculated by the ratio (γ) of carbon dioxide to oxygen based on a new mathematical model. The results showed that the employed method has good precision (the relative standard deviation < 5 %) and accuracy under the optimized equilibrium temperature and time (60 °C and 10 min). The method is simple and has a large measurable range, which can be an reliable tool for determining the carbonation rate in the carbonation process of PCC.

Safety Evaluation of the Combination with Dexrazoxane and Anthracyclines: A Disproportionality Analysis Based on the Food and Drug Administration Adverse Event Reporting System Database.

Objectives: As one of the important interventions to alleviate anthracycline-related cardiotoxicity (ARC), the safety assessment of dexrazoxane in clinical practice is particularly important. This study aims to evaluate the actual efficacy and potential adverse effects of dexrazoxane in clinical practice by analyzing the reports of adverse events (AEs) related to the combination with dexrazoxane and anthracyclines. Methods: We utilized four disproportionality analysis methods to analyze AE reports of the combination with dexrazoxane and anthracyclines in the Food and Drug Administration Adverse Event Reporting System (FAERS) database from the third quarter of 2014 to the first quarter of 2024. Results: Under the three backgrounds, a large number of preferred terms (PTs) such as cardiac failure disappeared in the combined group, and the PTs with significant signal values were mainly concentrated in infections and infestations. For patients under 18, some PTs associated with infections and infestations disappeared after the combination of the two drugs. Conclusions: Dexrazoxane can effectively alleviate ARC, but it may also increase the risk of infection. For infections and infestations, children under 18 years old are more likely to benefit from the combination therapy. More attention should be paid to infectious AEs in the clinical use of dexrazoxane, though disproportionality analysis is a hypothesis-generating approach.

Congenital anomalies associated with the use of cardiovascular drugs during pregnancy: a large-scale data analysis from the FAERS database

ABSTRACT Background Cardiovascular drugs can cross the placenta during pregnancy, potentially exposing the fetus to teratogenic effects. However, ethical constraints on clinical trials with pregnant women limit safety data and result in inadequate drug labeling. Research Design and Methods Using the FAERS database (2004–2023), we conducted a retrospective pharmacovigilance study analyzing adverse event reports involving congenital anomalies in newborns (<28 days). Signal detection methods included Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and Multi-item Gamma Poisson Shrinker (MGPS). Our analysis concentrated on the systems or organs involved in the signals, particularly those with higher report counts or signal values, to explore the association between drugs and congenital abnormalities. Results Among 6,208 cases of congenital anomalies in newborns, 387 were linked to cardiovascular drugs, generating 97 signals for 16 drugs. Strong signals included sartans (renal failure, skeletal deformity), metoprolol (hypospadias, large-for-dates baby), amlodipine (gastrointestinal malformations), and statins, furosemide, and spironolactone (dysmorphism). Conclusions Enhanced monitoring is recommended for fetal malformations in women exposed to these drugs before or during pregnancy. While our findings suggest associations, they do not establish causality, highlighting the need for further research to ensure medication safety during pregnancy.

ON THE SIMULTANEOUS DETERMINATION OF THE DENSITY DISTRIBUTION OF EQUIVALENT SOURCES UNDER AN EXTERNAL FIELD AND THE SPECTRUM OF USEFUL SIGNAL

The article investigates the possibility of simultaneously recovering equivalent sources under an external field and the spectral characteristics of a useful signal. Examples of variational formulations for different versions of the method of linear integral representations are presented, and the problem of finding the density distribution of gravitating or magnetic masses on several horizontal planes is formulated. Additionally, the Fourier transform of the anomalous field element based on the known signal values at certain observation points, complicated by noise, is discussed.

External Factors Influence on Defects Detection by Scanning Contact Potentiometry

Scanning contact potentiometry (SCP) method was used to detect structural inhomogeneities in a welded joint under the application of heat and constant electric current. For this purpose, a special sample was prepared, welded by manual arc welding from two halves of X8CrNiTi18-10 (Chromium-Nickel-titanium stainless Steel) austenitic steel, each with dimensions of 200×110×13.5mm. After welding, welded sample was inspected using X-ray radiography. The sample was stored for five months at room temperature, and the sample surface was scanned using different scanning speed ranging from 0.36 to 1.8 mm/sec. It was found that when scanning speed was increased, the signal values remained the same. In another experiment, a constant electric current was passed through the sample from 0.01 to 0.1A. Applying current led to the excitation of weak structural inhomogeneities from the welding joint butt, although it was machined. While heat led to an increase in diagnostic signal amplitude.

Robust preview tracking control for LPV/LFR continuous-time systems

This study proposes a novel preview control method for linear parameter-varying (LPV) continuous-time systems (CTS) utilizing linear fractional representation (LFR). First, a formal system equivalent to the LFR of the LPV continuous system, which includes the preview compensation and tracking error, was developed to use the available reference signal values. In order to give innovative preview controller designs, the suggested conditions then depend on the utilization of decision matrices and slack variables related to the LFR technique. To provide minimal conservative synthesis criteria to the LPV/LFR continuous-time system, parameter-dependent Lyapunov functions and full-block multipliers were also taken into consideration. To create reliable state-feedback and output-feedback tracking controllers with preview actions, the design conditions were modeled as linear matrix inequalities (LMIs). Two scenarios were simulated to show how effective the suggested control strategy is.