Search Results (2,003)

Background/Methods: The influence of sex on brain organization was investigated in functional reading networks in 8-year-old children, in those typically developing and those with developmental dyslexia (DD), utilizing the minimum spanning tree model. Results: The word reading task revealed subtle sex differences in brain connectivity and highlighted even small individual variations in functional connectivity characteristics, particularly among boys with DD. In girls, significantly stronger connections and core hubs were identified within and between motor, parietal, and visual networks in posterior brain regions in both hemispheres, particularly in the θ (dyslexics) and δ (normolexics) frequency bands. In contrast, boys showed a more diffuse connectivity pattern, predominantly in the left hemisphere, encompassing anterior heteromodal and sensorimotor networks. Girls exhibited greater network complexity (bigger leaf fraction, kappa, and tree hierarchy), particularly in the θ and δ frequency bands, while boys with DD showed increased network efficiency, except for in the γ2 band (smaller diameter and bigger leaf fraction). Therefore, gender-specific differences in brain network organization may affect reading development and dyslexia. While sex may influence brain network development, its impact on the sensorimotor and frontoparietal networks of 8-year-old children is relatively limited. Significant sex differences were observed in only a small subset of children, primarily in higher (β2-γ2) frequency bands. Conclusions: Interindividual variations were evident only in boys with DD, impacting both sensorimotor and association networks. Different rates of cortical network maturation between sexes with DD during childhood may contribute to variations associated with disruptions in brain network development, even within fundamental networks like the sensorimotor network. Full article

Gazing toward humans is fundamental in dog–human communication. This study aimed to characterize companion dogs based on their gazing behavior and to explore the potential links between gazing, personality (liveliness, confidence, aggressiveness, and attachment), emotional comfort provided to the owners, and breed. We observed 171 dogs in an ambiguous situation involving a moving stimulus, a remote-controlled toy car and gathered additional data with questionnaires. Our behavior analysis, based on gaze frequency directed at the owner and experimenter, identified four distinct clusters of dogs: low gazers, experimenter-focused gazers, owner-focused gazers, and frequent gazers. We found that experimenter-focused gazers exhibited lower levels of liveliness than frequent gazers and were reported to be less aggressive than low gazers and frequent gazers. Owner-focused gazers provided more emotional comfort to their owners than low gazers. Regarding breeds, 56.5% of German shepherd dogs were low gazers, compared to only 5.3% of golden retrievers. Age, sex, neutered status, and approaching the stimulus were not associated with cluster membership. These results highlight the complexity of dog–human communication, suggesting that personality, emotional factors, and breed shape how dogs seek guidance and support from humans or express anxiety. Full article

Recently, there is a renewed interest from the scientific community in the study of the electrical signal generated by plants due to its wide range of applications in agriculture, for example, environmental monitoring, detection of pests, diseases in crops, etc. Therefore, the aim of this work is to characterize the electrical signal of Aloe vera var. chinensis by using non-parametric and parametric signal analysis techniques, in order to extract some fundamental features which could be used in the design of a bio-dosimeter. Non-parametric analysis of the signal was carried out in the time, frequency, and time-frequency domains, using the short-time Fourier transform (STFT) and the wavelet transform in order to determine the different characteristics and frequency changes over time. Parametric analysis was then performed by using auto-regressive (AR) models for signal prediction and modeling, and in this case the coefficients of the model will be considered as fundamental features to be extracted. It has been identified that the majority of the signal energy is found in low frequencies, possibly associated with physiological processes or changes in the environment. Subsequently, some metrics like mean squared error (MSE), mean absolute error (MAE), and coefficient of determination (R²) were used in order to establish the capability of modeling the signal in its totality, considering that it is affected by the abrupt changes present in the signal. In this way, the relevance of combining both analyses is discussed in order to take their advantages for the benefit of the compression and feature extraction of the electrical signal of Aloe vera var. chinensis. This analysis allows the Aloe vera var. chinensis plant to be used for environmental monitoring, pest and disease detection in crops, or in a pattern recognition and signal classifier systems. Full article

It is certain that electrical properties—whether slow (sec) or fast (nsec), even optical (fsec)—are described by Maxwell’s equations, and there are terms that depend on the rate of the change of the electric and magnetic fields. In particular, Maxwell’s equation for the curl of the magnetic field contains both the steady-state conduction current and a term depending upon the temporal derivative of the electric displacement field. The latter is referred to as the displacement current and is generally believed to have been included originally by Maxwell himself, although there is evidence it was earlier considered by Kirchhoff. Maxwell’s equations and Kirchoff’s circuit laws both are important over the wide range of frequencies with which electronics traditionally deal. Additionally, the displacement current is an important contribution to these in both classical and quantum mechanics. Here, the development of the displacement current, its importance in both classical and quantum mechanics, and some applications are provided to illustrate the fundamental role that it plays in the dynamics of a wide range of systems. Full article

Vibrations observed as a result of moving vehicles can potentially affect both buildings and the people inside them. The impacts of these vibrations are complex, affected by a number of parameters, like amplitude, frequency, and duration, as well as by the properties of the soil beneath. These factors together lead to various effects, from slight disruptions to significant structural damage. Occupants inside affected buildings may experience discomfort, disrupted sleep patterns, and increased stress levels due to the pervasive nature of vibrations. Low-frequency vibrations, typically ranging from 5 to 25 Hz, are of particular concern since they can exacerbate these effects by resonating with internal human organs. To effectively mitigate these issues, a comprehensive approach is required, starting with some interventions at the source. This may involve strategic choices in road construction materials and advancements in vehicle design to reduce the transmission of vibrations through the ground to the surrounding environment. Understanding the complexities of vibration dynamics is essential in urban planning, serving as a fundamental consideration in the development of modern infrastructure that prioritizes the well-being and safety of its inhabitants. Therefore, the aim of the present study is to consider artificial neural networks to assess the potential impact of traffic-induced vibrations on a building’s residents. The results of the study indicate that the proposed method of utilizing machine learning can be effectively applied for such purposes. Full article

This paper presents the design and the performance of a wide tuning-range millimeter-wave (mm-wave) two-core class-C 60 GHz VCO in 40 nm CMOS process, which can be integrated into wireless communication transceivers and radar sensors. The proposed architecture consists of a two-core 30 GHz fundamental VCO, a gain-boosted frequency doubler and an adaptive bias configuration. The two-core fundamental VCO structure achieves frequency generation in the vicinity of 30 GHz, where each VCO core targets a different frequency band. The two bands have sufficient overlap to accommodate for corner variations providing a large continuous tuning range. The desired frequency band is selected by activating or deactivating the appropriate VCO core, resulting in a robust switchless structure. This approach enables a considerably broad tuning range without compromising phase noise performance. Furthermore, the proposed topology utilizes an adaptive bias mechanism for robust start-up. Initially, the selected VCO core begins oscillating in class-B mode, and subsequently it transitions into class-C operation to offer improved performance. From post-layout simulations, after frequency doubling, the low-band VCO covers frequencies from 50.25 to 60.40 GHz, while the high-band VCO core spans frequencies from 58.8 to 73 GHz, yielding an overall tuning range of 36.92%. Owing to the gain-boosting topology, output power exceeds −14.2 dBm across the whole bandwidth. Simulated phase noise remains better than −92.1 dBc/Hz at a 1 MHz offset for all bands. Additionally, the two VCO cores never operate simultaneously, aiding in power efficiency. Full article

This paper tests the capability of a simplified model to predict major trends in the dynamic structural response of monopile offshore wind turbines. For this purpose, the results of two numerical models of different levels of complexity are compared: the advanced time-domain multi-physics tool OpenFAST and a simplified static-equivalent model based on beam elements and concentrated masses. The IEA-15-240-RWT reference wind turbine is considered as a benchmarking problem. The comparison between the two structural models is presented in terms of their fundamental frequencies and through the analysis of shear forces and bending moments under wind-only and combined wave and wind load scenarios. The results show that the simplified model can adequately represent the system’s mass and stiffness characteristics, as well as the impact of soil–structure interaction effects on its fundamental frequency. Turbulence and wind velocity have a significant impact on internal forces and on the ability of the simplified model to reproduce their values. Despite the large differences obtained for highly turbulent scenarios, the acceptable accuracy obtained for relevant load scenarios and the conservative nature of the simplified model make it a viable option for preliminary large-scale studies that prioritize efficiency and efficacy over high-precision. Full article

The dielectric constant, or permittivity, is a fundamental property that characterizes a material’s electromagnetic behavior, crucial for diverse applications in agriculture, healthcare, industry, and scientific research. In microwave engineering, accurate permittivity measurement is essential for advancements in fields such as biomedicine, aerospace, and microwave chemistry. However, conventional waveguide resonator methods face challenges when measuring high-loss materials, often leading to reduced accuracy and increased cost. This paper introduces a lightweight, compact system for dielectric constant measurement using a negative-resistance voltage-controlled oscillator (VCO) integrated within a frequency synthesizer. The proposed system employs phase response variations of a planar sensor embedded in the VCO’s gate network to detect changes in oscillation frequency, enabling precise measurement of high-loss materials. The experimental validation demonstrates the system’s capability to accurately measure dielectric constants of lossy organic liquids, with applications in distinguishing liquid mixtures. The contributions include the design of a resonant-network-attached oscillator, comprehensive sensor performance simulations, and successful characterization of organic liquid mixtures, showcasing the potential of this approach for practical dielectric property measurements. Full article

The execution of a construction project faces many potentials challenges, and delays are one of them. Communal construction projects in Burundi (CCP-Burundi projects) were considered as one field that could generate a Burundi government development plan. However, according to the frequency of delays encountered by these projects, at a rate of 70% on average every year, the government’s target seems far from being achieved. As no scientific study exists on how to avoid CCP delays, this paper aims to identify and analyze factors that cause delays in CCP-Burundi and provide related measures to overcome them. Based on a list of fifty delay factors gathered from the National Communal Investment Fund institution FONIC (Fond National d’Investissement Communal), communal annual reports, and the literature, a questionnaire survey was developed and dispersed to CCP stakeholders to collect data about critical factors. The top fifteen factors were identified using a relative importance index and a factor analysis was performed. “Weather conditions” was the top-ranked factor, while “Claims” was the lowest ranked. A structural equation modeling approach was adopted to evaluate influences at the relationship level among delay factor groups. A standardized calculation revealed that Factors During Awarding of Bid (FDABs) positively influence Factors After the Award of Bid (FAABs). The findings were implemented in case studies to assess their efficacy. This paper’s findings could assist upcoming construction practitioners and future researchers aiming to explore construction-related project delays, providing a fundamental understanding of the significant delays encountered in the Burundi construction industry. Full article

With the recent increase in retail investor participation led by commission-less fintech trading applications and new features like fractional trading, we now have higher volatility and significantly quicker price changes. This makes it hard to make informed trading decisions. Moreover, these effects are exacerbated even further around earnings announcements days. In this paper, we use Nasdaq data feed at a minute frequency and show that there is a significant increase in the slope of the price–volume structure during extended hours (after-hours, or pre-market hours) as compared with the ones observed during regular market times. Our analysis shows that the liquidity is much less during the extended market hours. As such, earnings announcements of stocks during these times have a significantly larger price impact than those stocks that have their earnings announced during regular trading hours. This significant difference can be explained by observing the limit order book structures during these different trading periods. We suggest that the earnings announcements should not be made during extended hours given the significantly lower liquidity and thus, the significantly larger price impact that not only determines the prices for the next trading session but also sets the new “fundamental” price signals for the stocks. Full article

Rock bolting in underground environments is used for different fundamental reasons, including suspending potentially loosened blocks, clamping small wedges together, inducing a protective pressure arch along the contour of excavated voids to improve the self-supporting capacity of the ground, and providing passive pressure in integrated support systems. In this study, we describe a testing procedure that was developed to investigate the grouted annulus of a rock bolt using a low-cost investigation method. This diagnostic technique was based on the dynamic response of the system, where mechanical vibrations were induced within the rock bolt and the response was recorded by using geophones/accelerometers on the protruding element of the bolt (the collar and head). The collected signal was then processed to estimate the spectral response, and the amplitude spectrum was analyzed to detect the resonance frequencies. A 3D finite element model of the rock bolt and grouting was established to simulate the quality of the coupling by varying the mechanical properties of the grouting. The model’s response for the studied geometry of the rock bolt suggested that a poor quality of grouting was usually associated with flexural modes of vibration with a low resonance frequency. Good-quality grouting was associated with a frequency higher than 1400 Hz, where the axial vibration was mainly excited. Our analyses referred to short rock bolts, which are usually adopted in small tunnels. The interpretation of the experimental measurements assumed that the spectral response was significantly affected by the quality of the grouting, as demonstrated by the modeling procedure. The resonant frequency was compared with the results of the model simulation. The method was used to test the quality of rock bolts in a small experimental tunnel carved from andesite rock in Chile. Low-cost shock sensors (piezoelectric geophones) with low sensitivity but a wide frequency band were used. The main research outcome was the development of a reliable method to model the dynamic response of rock bolts in mines or for experimental applications in tunnels. Albeit limited to the current specific geometries, the modeling and testing will be adapted to other anchor/bolt options. Full article

Groundwater resources from the volcanic aquifers of northern Latium (central Italy) are widely used to supply local water needs and are mainly captured through wells. Nevertheless, despite the detailed hydrogeological knowledge of these aquifers, not enough information is available on the long-term pumping yield necessary to define the sustainable yield of a well. In this study, data from about 230 pumping tests (mainly step-drawdown and a few constant-flow-rate tests) performed in the volcanic aquifers of the Latium region were analyzed. Specifically, the aquifer formations intercepted by the wells are the fall and flow pyroclastic deposits of the Vico, Vulsini, and Sabatini volcanic districts; lava from the Vico, Cimino, and Vulsini volcanic districts; and Ignimbrite Cimina, one of the main pyroclastic products of the Cimino eruptions. These aquifers were grouped and analyzed by considering the type of permeability, hydrostratigraphic succession, and frequency and thickness of the aquifer horizons intercepted by wells. The results obtained in terms of specific capacity and transmissivity values are comparable among the identified different aquifer formations, showing a good correlation between the two parameters, a strong hydraulic heterogeneity (variability within five orders of magnitude), and variable responses regarding drawdown to pumping. This study highlights that the analysis of drawdown over time at a constant flow is fundamental in heterogeneous hydrogeological environments such as volcanic ones, where the trend in drawdown is often affected by the reduced spatial continuity of the most productive aquifer formations. Knowledge of the trend in drawdown over time, the thickness of the aquifer intercepted by the well, and the operating time of the well is an essential element in defining the sustainable yield of a well. Full article

While transitive clauses with a subject and object have long been a fundamental focus of grammatical analyses across languages of the world, more recently, it has become apparent that naturally occurring language-in-use is in fact overwhelmingly intransitive and transitive clauses with two arguments have a relatively low frequency. In this study, I examine conversational Indonesian and focus on one construction type, a transitive predicate with two explicit core arguments. This grammatical configuration is considered atypical due to its very low frequency in conversational interaction. The goal of the study is to begin to understand when and why expressions of this type appear. It is found that these atypical configurations regularly occur at points where there is a change in footing, including changes in topic, participation framework, or referentiality. It is further shown that the contrast between explicit and unexpressed arguments in Indonesian conversational grammar contributes to the reasons why predicates elaborated with two arguments tend to appear when there is a change in footing. Full article

In many tasks of railway vibration, the structure, that is, the track, a bridge, and a nearby building and its floors, is coupled to the soil, and the soil–structure interaction and the damping by the soil should be included in the analysis to obtain realistic resonance frequencies and amplitudes. The stiffness and damping of a variety of foundations is calculated by an indirect boundary element method which uses fundamental solutions, is meshless, uses collocation points on the boundary, and solves the singularity by an appropriate averaging over a part of the surface. The boundary element method is coupled with the finite element method in the case of flexible foundations such as beams, plates, piles, and railway tracks. The results, the frequency-dependent stiffness and damping of single and groups of rigid foundations on homogeneous and layered soil and the amplitude and phase of the dynamic compliance of flexible foundations, show that the simple constant stiffness and damping values of a rigid footing on homogeneous soil are often misleading and do not represent well the reality. The damping may be higher in some special cases, but, in most cases, the damping is lower than expected from the simple theory. Some applications and measurements demonstrate the importance of the correct damping by the soil. Full article

Slope failures caused by changes in soil moisture content have become a growing global concern, resulting in significant loss of life and economic damage. To ensure the stability of slopes, it is necessary to accurately monitor the moisture content and understand the complex interactions between soil, water, and slope behavior. This paper provides a comprehensive overview of advanced soil moisture detection techniques for unsaturated soil slopes, including point-scale measurements and geophysical methods. It first introduces the fundamental concepts of the soil–water characteristic curve (SWCC) and its influence on the shear strength and stability of unsaturated soil slopes. It then delves into the working principles and applications of various point-scale measurement techniques, such as time-domain reflectometry (TDR), frequency-domain reflectometry (FDR), and neutron probe methods. Additionally, this paper explores the use of geophysiDear Editor: The author has checked that the name and affiliation are accuratecal methods, including ground-penetrating radar (GPR), electrical resistivity tomography (ERT), and electromagnetic induction (EMI), for the non-invasive assessment of soil moisture conditions and slope stability monitoring. This review highlights the advantages of integrating multiple geophysical techniques, combined with traditional geotechnical and hydrological measurements, to obtain a more comprehensive understanding of the subsurface conditions and their influence on slope stability. Several case studies are presented to demonstrate the successful application of this integrated approach in various slope monitoring scenarios. The continued advancement in these areas will contribute to the development of more accurate, reliable, and widely adopted solutions for the assessment and management of slope stability risks. Full article