Frequency Bias Research Articles

Nonlinear bias of collective oscillation frequency induced by asymmetric Cauchy noise.

We report the effect of nonlinear bias of the frequency of collective oscillations of sin-coupled phase oscillators subject to individual asymmetric Cauchy noises. The noise asymmetry makes the Ott-Antonsen ansatz inapplicable. We argue that, for all stable non-Gaussian noises, the tail asymmetry is not only possible (in addition to the trivial shift of the distribution median) but also generic in many physical and biophysical setups. For the theoretical description of the effect, we develop a mathematical formalism based on the circular cumulants. The derivation of rigorous asymptotic results can be performed on this basis but seems infeasible in traditional terms of the circular moments (the Kuramoto-Daido order parameters). The effect of the entrainment of individual oscillator frequencies by the global oscillations is also reported in detail. The accuracy of theoretical results based on the low-dimensional circular cumulant reductions is validated with the high-accuracy "exact" solutions calculated with the continued fraction method.

Weight stigma in pediatric type 1 diabetes: An associated risk for disordered eating?

Adolescents with type 1 diabetes (T1D) have elevated eating disorder risk. No studies have examined weight stigma as a potential factor associated with disordered eating. This study investigated cross-sectional associations among weight-based victimization, weight bias internalization, and disordered eating in adolescents with T1D. Adolescents (12-17 years; N = 166) self-reported experiences of weight-based victimization from peers, family members, and healthcare professionals. The Weight Bias Internalization Scale (WBIS) and Diabetes Eating Problems Survey (DEPS-R) assessed internalized weight bias and disordered eating, respectively. In a series of multiple hierarchical linear regression analyses (controlling for zBMI, diabetes duration, HbA1c, sex), weight bias internalization, weight-based victimization, and frequency of weight-based victimization by peers, family, and healthcare professionals were all positively associated with disordered eating. Weight stigma is an understudied but potentially important factor to address in adolescents with T1D. Reducing weight stigma may be a promising, novel target for eating disorder prevention in this population.

IUCN Red List criteria fail to recognise most threatened and extinct species

Many species have benefited from management actions associated with listing as threatened on the IUCN Red List, resulting in fewer extinctions relative to business as usual. Red List criteria used to categorise threat status have, however, been designed with primary focus on higher vertebrates, and consequently produce inconsistent and deficient threat assessments for other taxa. Equally valid decisions on population trend shape, generation length, period of assessment, and habitat quality can result in threat status determinations ranging from Least Concern to Critically Endangered. Moreover, inconspicuous species exhibiting catastrophic population decline to below detection limits can ultimately be regarded as Data Deficient, thus categorised as neither extinct nor threatened. Under-estimation of extinction frequency biases our understanding of global environmental change and the urgent need for societal action. Improved extinction risk assessments can be achieved with changes and simplification of Red List criteria, and detailed case examples that guide progress through decision-points.

Analysis of bit error rate and receiver sensitivity of a DC biased optical OFDM transmission link using single mode fiber with distributed Raman amplifier

Abstract In this paper, an analytical method is presented to assess the performance of bit error rate (BER) of a DC biased optical orthogonal frequency division multiplexing (DCO-OFDM) SMF transmission with distributed Raman amplifier (DRA). Formulas are developed to determine the signal-to-noise ratio (SNR) at the output of a DCO-OFDM receiver and the bit error rate (BER) for an OFDM demodulator’s output. By considering the Gaussian probability density function (pdf) for the OFDM demodulator output, the average BER is calculated numerically. The results are presented based on receiver sensitivity, bit error rate and optical SNR at a given BER of 10−9, with variations in system parameters such as input signal power, data rate, fiber distance, modulation index and OFDM sub-channel number. A comparison of BER performance indicates that DC biased optical OFDM with intensity modulation direct detection (DCO-DD-OFDM) offers better receiver sensitivity compared to optical OFDM without DC bias at a BER of 10−9. Our analytical results align with the published findings on optical OFDM.

Availability bias and heterogeneity in saliency, recency, and frequency of promotions for plant-based foods: a naturalistic observation

Availability bias and heterogeneity in saliency, recency, and frequency of promotions for plant-based foods: a naturalistic observation

Assessing global ensemble systems’ forecasts of tropical cyclone genesis in differing environmental flow regimes in the western North Pacific

The forecast probability of tropical cyclone (TC) genesis in the western North Pacific from 2017 to 2020 was investigated using global ensembles from the Japan Meteorological Agency (JMA), the European Centre for Medium-Range Weather Forecasts (ECMWF), the U.S. National Centers for Environmental Prediction (NCEP), and the Met Office in the United Kingdom (UKMO). The time of TC genesis was defined as the time the TCs were first recorded in the best-track data (Case 1) and as the time they reached the intensity of a Tropical Storm (Case 2). The results in Case 1 showed that differences between the forecast probability based on each global ensemble were large, even for a 1-day forecast, and that mean probability were from 18 % to 74 %. The forecasts based on the NCEP had a large frequency bias and overpredicted TC genesis events. The results indicated that the representation of genesis events differed greatly between global ensembles. The effectiveness of multiple ensembles was investigated. The results from the threat score and the false alarm ratio indicated that multiple ensembles had skillful forecasts. When the forecast probability was examined for environmental patterns of synoptic low-level flow, the mean 5-day forecast probability was highest for the pattern in the confluence region. The results also showed that the forecast probability was much larger in Case 2 than in Case 1. In all global ensembles, the mean probability with a lead time of up to 1-week was below 10 % for both Case 1 and 2. This result indicates that even with today's operational forecasting systems, it is difficult to regularly predict TC genesis events with a 1-week lead time with high confidence. These results provide a better understanding of TC genesis forecast products in each global ensemble and will be useful information when multiple-ensemble products are created.

Indonesian Teachers’ Perspectives on Gender Representation in EFL Textbook Visual Images for Elementary Schools

Background: The use of gendered visual imagery in English as a Foreign Language (EFL) textbooks has raised concerns about perpetuating gender stereotypes and the potential effect on students' conceptions of gender roles. Despite the widespread use of mandated textbooks in primary classrooms in Indonesia, less is known about instructors' perceptions of gendered visual imagery. Methodology: This qualitative research employed a mixed-methods approach, incorporating quantitative and qualitative data collection and analytic methodologies. An investigation was conducted in Samarinda East Kalimantan to collect the perspectives of 41 teachers who teach English in elementary school regarding the gendered visual representations present in the mandatory EFL textbooks. Furthermore, 12 teachers were chosen to partake in exhaustive interviews to present more informed and profound perspectives. Findings: They merely focused on how to teach the materials rather than scrutinizing the gender bias represented through texts and visual images. The study revealed that a significant proportion of teachers (80%) believed that gendered visual imagery in textbooks was not impartial and could influence the gender roles of pupils. Furthermore, a significant majority (75%) said they often adjusted or avoided using these pictures in their teaching methods. The interviews highlighted the teachers' concern about the possible negative impact of these pictures on students' social relationships and self-image. However, they merely focused on how to teach the materials rather than scrutinizing the gender bias represented through texts and visual images Conclusion: The findings suggest that elementary school teachers in Indonesia know the potential negative repercussions of gendered visual images in EFL textbooks and have implemented measures to mitigate these effects. The study underscores the importance of incorporating diverse and inclusive visual materials into educational resources to promote gender equality and positive gender representations. This concept is new to them. They agree that gender equality needs to be addressed and discussed as part of the content in classroom practices to raise students’ awareness of gender bias. Originality: Previous studies have investigated the frequency and occurrence of gender bias in textbooks, found in images and texts. However, there is a lack of investigation into teachers' awareness of gender stereotypes in textbooks. This study enhances the existing corpus of literature by examining the perspectives of teachers on the use of gendered visual images in EFL textbooks in elementary schools in Indonesia. It emphasizes the importance of teachers and policymakers advocating for more inclusive educational resources and considering the impact of visual materials on students' gender perceptions

Analysis of the synergetic effect of process parameters of hydrogenated amorphous carbon deposition in plasma-enhanced chemical vapor deposition using machine learning

The synergetic effects of process parameters on hydrogenated amorphous carbon (a-C:H) films properties were quantitatively analyzed in plasma-enhanced chemical vapor deposition. Predictive models, created from experimental datasets and machine learning, indicate a synergetic effect between the H2 ratio and ion energy impacting on the substrate. At a H2 ratio of 75 %, etch rates of 200 nm/min were predicted, regardless of radio frequency (RF) bias. These rates decreased to 120–140 nm/min at lower H2 ratios, primarily depending on RF bias. Quadrupole mass spectrometry and Raman scattering were used to investigate the underlying mechanisms. High H2 ratios led to a greater presence of low-mass hydrogen-rich molecules in the plasma. The C2H3 radical intensity at a 75 % H2 ratio was 15 times greater than that at 0 % at an RF bias of 50 W, and similar trends were observed for other low-mass neutrals. The synergetic effects of H2 ratio and RF bias decreased the film's hydrogen content. Machine learning and those diagnostics revealed that ion bombardment induces dehydrogenation of a-C:H, influenced by hydrogen-rich species. This study demonstrates that machine learning can uncover complex plasma processes and optimize material synthesis.

Enhanced salience of edge frequencies in auditory pattern recognition.

Within musical scenes or textures, sounds from certain instruments capture attention more prominently than others, hinting at biases in the perception of multisource mixtures. Besides musical factors, these effects might be related to frequency biases in auditory perception. Using an auditory pattern-recognition task, we studied the existence of such frequency biases. Mixtures of pure tone melodies were presented in six frequency bands. Listeners were instructed to assess whether the target melody was part of the mixture or not, with the target melody presented either before or after the mixture. In Experiment 1, the mixture always contained melodies in five out of the six bands. In Experiment 2, the mixture contained three bands that stemmed from the lower or the higher part of the range. As expected, Experiments 1 and 2 both highlighted strong effects of presentation order, with higher accuracies for the target presented before the mixture. Notably, Experiment 1 showed that edge frequencies yielded superior accuracies compared with center frequencies. Experiment 2 corroborated this finding by yielding enhanced accuracies for edge frequencies irrespective of the absolute frequency region. Our results highlight the salience of sound elements located at spectral edges within complex musical scenes. Overall, this implies that neither the high voice superiority effect nor the insensitivity to bass instruments observed by previous research can be explained by absolute frequency biases in auditory perception.

Are cleft sentence structures more difficult to process?

This study compares the processing of cleft structures against that of monoclausal sentences using event-related potential (ERP). We aim to understand how syntactic complexity is processed by comparing the neural response to cleft and single-clause sentences with identical verb phrases, controlling for verb bias frequency effects. Sixty participants were tested, and we presented 100 cleft and 100 monoclausal sentences, balanced for active and passive verb usage. We examined the P600 component, an ERP associated with syntactic complexity, to assess the processing of cleft structures. Results showed that cleft structures incur a greater processing load, as indicated by a larger P600, compared to monoclausal sentences. The P600 response indicates that processing cleft sentences requires additional syntactic operations, consistent with behavioral studies showing that clinical populations have difficulty comprehending complex sentences.

Is there a bias in the codon frequency corresponding to homo-repeats found in human proteins?

It is well known that there is a codon usage bias in genomes, that is, some codons are observed more often than others. Codons implicated in the homo-repeats regions in human proteins are no exception. In this work, we analyzed the codon usage bias for all amino acid residues in homo-repeats larger than 4 in 3753 human proteins from 20447 protein sequences from the canonically reviewed human proteome. We have discovered that almost all homo-repeats in the human proteome, most of which encode Ala, Glu, Gly, Leu, Pro, and Ser (∼80% of all homo-repeats), have a codon usage bias, i.e. are mainly encoded by one codon. Moreover, there is a strong shift in homo-repeats in favor of the content of GC rich codons. Homo-repeats with Ala, Glu, Gly, Leu, Pro, and Ser predominate in the PDB, which has both ordered and disordered status. Examining the distribution of splicing sites, we found that about 15% of homo-repeats either contain or are located within 10 nucleotides of the splicing site, and Glu and Leu predominate in these homo-repeats. Our data is important for future study of the functions of homo-repeats, protein-protein interactions, and evolutionary fitness.

Mercury-probe measurement of electron mobility in β-Ga2O3 using junction moderated dielectric relaxation

We demonstrate the junction-moderated dielectric relaxation method to measure the in-plane electron mobility in β-Ga2O3 epitaxial layers. Unlike the Hall technique and channel mobility measurement in field-effect transistors, this method does not require the deposition of permanent metal contacts. Rather, it measures the bias voltage and frequency dependence of the equivalent capacitance of the Mercury/β-Ga2O3/Mercury structure consisting of a Schottky contact, a quasi-neutral thin film semiconductor, and an Ohmic contact connected in series. The intrinsic dielectric relaxation of the bulk β-Ga2O3 semiconductor typically occurs at ∼1012 s−1, but when moderated by the Mercury/β-Ga2O3 Schottky junction, it manifests itself as an inflection in the capacitance-frequency characteristics at a much lower frequency of ∼106 s−1 within the range of most capacitance measuring instruments. Using carrier density and layer thickness determined from capacitance-voltage measurement, we extract the electron mobility of β-Ga2O3 from the junction-moderated dielectric relaxation frequency.

Continuous GPS PPP-AR frequency transfer links

Abstract In this paper, we show that the SPARK software of the Natural Resources Canada (NRCan) with their DCR (Decoupled Clock Rapid) products can be used to generate the PPP-AR continuous batch clock solutions of multiple days, which we use to build frequency transfer links between two remotely located GPS receivers. The reliability and confidence in forming the long-term frequency transfer links have been improved compared to reference~\cite{jian2023gps}. We compare the SPARK PPP-AR links to an optical fiber and TWSTFT links for hundreds of days. The ∽500-day-long comparisons with TWSTFT show no frequency bias for continental and cross-continental links. Frequency transfer links formed using the SPARK solutions have uncertainty of 1×10-15/T, where T is in days, without reaching the noise floor, a critical requirement for comparing optical frequency standards and for the redefinition of the SI second. The short latency of the NRCan DCR products enables the quick availability of the PPP-AR links presented in this paper marking it particularly relevant for time sensitive applications.

GrainSense: A Wireless Grain Moisture Sensing System Based on Wi-Fi Signals

Grain moisture sensing plays a critical role in ensuring grain quality and reducing grain losses. However, existing commercial off-the-shelf (COTS) grain moisture sensing systems are either expensive, inconvenient or inaccurate, which greatly limit their widespread deployment in real-world scenarios. To fill this gap, we develop a system called GrainSense which leverages COTS Wi-Fi devices to detect the grain moisture without the need for dedicated sensors. Specifically, we propose a wireless grain moisture detection model based on the refraction phenomenon of Wi-Fi signals and the Multiple-Input-Multiple-Output (MIMO) technology. On one hand, we correlate the grain moisture with the phase difference between two refracted Wi-Fi signals that propagate along different paths, based on which grain moisture can be deduced accordingly. On the other hand, to reduce the multi-path interference in indoor environments (e.g., the granary), we adopt Wi-Fi beamforming to enhance the refracted signal. In particular, a new signal feature (i.e., the Wi-Fi CSI beamforming ratio) is designed to eliminate the effect of sub-carrier frequency bias and cumulative phase bias. To validate the effectiveness of the developed system, we conduct extensive experiments with different types of grains in both the laboratory and the granary. Results show that the system can accurately estimate the grain moisture with an mean absolute error smaller than 5%, which meets the requirements for commercial usage. To the best of our knowledge, this is the first model-based work that achieves accurate grain moisture detection based on wireless sensing.

A Subspace-Based Frequency Synchronization Algorithm for Multicarrier Communication Systems

We present a subspace-based polynomial rooting algorithm to estimate the frequency bias (FB) of generalized frequency division multiplexing (GFDM) systems employing null subcarriers and repetitive sub-symbols. The estimation process is classified into fractional FB (FFB) and integer FB (IFB) estimation. The use of repetitive sub-symbols creates a quasi-periodic structure in the FB-distorted received signal, allowing the proposed algorithm to estimate the FFB using the root-MUSIC algorithm. Based on this, the proposed algorithm compensates for the FFB in the received signal and then estimates the null subcarrier pattern (NSP) in the frequency domain. As a result, the IFB estimate can be obtained in a maximum likelihood (ML) manner. Before the NSP estimation, this study uses a sub-symbol combiner to enhance signal strength of the FFB-aligned signal, ensuring the reliability of the IFB estimate. Computer simulations show that the proposed subspace-based algorithm has several advantages over traditional FB estimation methods: 1. Unlike some existing algorithms that use a training sequence to estimate FB, the proposed approach is a semi-blind algorithm because it can deliver information through repeated sub-symbols while estimating FB; 2. The proposed algorithm demonstrates excellent estimation accuracy compared to most traditional FB estimation algorithms; and 3. The proposed algorithm is computationally efficient, making it applicable to real-time applications in future communication systems.

Frequency Bias Causes Overestimation of Climate Change Impacts on Global Flood Occurrence

AbstractThe frequency change of 100‐year flood events is often determined by fitting extreme value distributions to annual maximum discharge from a historical base period. This study demonstrates that this approach may significantly bias the computed flood frequency change. An idealized experiment shows frequency bias exceeding 100% for a 50‐year base period. Further analyses using Monte Carlo simulations, mathematical derivations, and hydrological model outputs reveal that bias magnitude inversely relates to base period length and is weakly influenced by the generalized extreme value distribution's shape parameter. The bias, persisting across different estimation methods, implies floods may exceed local defenses designed based on short historical records more often than expected, even without climate change. We introduce a frequency bias adjustment method, which significantly reduces the projected rise in global flood occurrence. This suggests a substantial part of the earlier projected increase in flood occurrence and impacts is not attributable to climate change.

Elevation-dependent biases of raw and bias-adjusted EURO-CORDEX regional climate models in the European Alps

Data from the EURO-CORDEX ensemble of regional climate model simulations and the CORDEX-Adjust dataset were evaluated over the European Alps using multiple gridded observational datasets. Biases, which are here defined as the difference between models and observations, were assessed as a function of the elevation for different climate indices that span average and extreme conditions. Moreover, we assessed the impact of different observational datasets on the evaluation, including E-OBS, APGD, and high-resolution national datasets. Furthermore, we assessed the bi-variate dependency of temperature and precipitation biases, their temporal evolution, and the impact of different bias adjustment methods and bias adjustment reference datasets. Biases in seasonal temperature, seasonal precipitation, and wet-day frequency were found to increase with elevation. Differences in temporal trends between RCMs and observations caused a temporal dependency of biases, which could be removed by detrending both observations and RCMs. The choice of the reference observation datasets used for bias adjustment turned out to be more relevant than the choice of the bias adjustment method itself. Consequently, climate change assessments in mountain regions need to pay particular attention to the choice of observational dataset and, furthermore, to the elevation dependence of biases and the increasing observational uncertainty with elevation in order to provide robust information on future climate.

Bonobo geophagy at Wamba.

Geophagy, the deliberate consumption of earth materials, is widely observed in animals. While anecdotal evidence exists of bonobos (Pan paniscus) consuming soil from Cubitermes termite mounds, the functions of their geophagic behavior remains unexplored. This study aims to examine a preliminary hypothesis that termite mound geophagy of free-ranging bonobos at Wamba are helpful for iron supplementation. Here, we tested the following three predictions: (1) the soil of Cubitermes termite mounds at Wamba would have high iron content, (2) bonobos would engage in termite mound geophagy regularly across all seasons, and (3) termite mound soil would be more often consumed by (a) females than males, (b) pregnant than non-pregnant females, and (c) adolescents than adults. As predicted, soil samples collected from the pointy protrusions on the caps of the mushroom-shaped mounds, the part typically consumed by bonobos, had a much higher iron content than other food items for them. In addition, geophagic behavior was noted on 48 out of 116 days (41.3%) with full-day focal animal sampling, and was observed throughout the entire study duration without any bias in frequency toward a certain period. However, contrary to our prediction, there was no significant variation in the frequency of geophagic behavior by sex nor by pregnancy status, although it occurred more frequently among adolescents than adults. Our findings partially support the Iron Supplementation Hypothesis, suggesting that Cubitermes termite mound soils could offer a readily accessible source of iron for bonobos. However, we cannot draw definitive conclusions on the function of their geophagic behavior from our findings without in vitro studies examining whether the ingested iron is bioavailable and whether the soil does not have properties inhibiting iron absorption. Nonetheless, this study is a first step to explore the health implications of geophagy in bonobos, extending our knowledge of this behavior in primates.

Efficient fabrication technique and dynamic property characterization of macro fiber composites

This paper proposes an efficient technique for the fabrication of macro fiber composite (MFC) and characterizes the properties of MFC under dynamic voltage. First, the fabrication process is described in detail. Then, the effects of peak-to-peak value, frequency and dc bias on the electric-field-induced strain are analyzed. Finally, the mechanical properties are evaluated based on the mixing rules, and the prediction model of electrical parameters is established using the fitting functions. The experimental results show that the proposed fabrication technique effectively suppresses the generation of defects and the electric field variation has significant effects on the actuating properties.

Effect of Bias Frequency on Bottom-Up SiO2 Gap-Filling Using Plasma-Enhanced Atomic Layer Deposition.

High-aspect-ratio patterns are required for next-generation three-dimensional (3D) semiconductor devices. However, it is challenging to eliminate voids and seams during gap-filling of these high-aspect-ratio patterns, such as deep trenches, especially for nanoscale high-aspect-ratio patterns. In this study, a SiO2 plasma-enhanced atomic layer deposition process incorporated with ion collision using bias power to the substrate was used for bottom-up trench gap-filling. The effect of bias power frequency on SiO2 trench gap-filling was then investigated. Results showed that changes in bias power frequency did not significantly change the process rate, such as SiO2 growth per cycle. At relatively low bias power frequencies, high-energy ions formed an overhang at the entrance of the high-aspect-ratio trench pattern through sputter etching and redeposition, blocking the pattern entrance. However, at relatively high-frequency bias power, overhang formation due to sputtering did not occur. In the trench interior, due to a scattering effect of ions, deposition was thicker at the bottom of the trench than that at the top, achieving bottom-up gap-filling and void-free gap-filling.