Length Frequency Research Articles

Determination of the coherence length and beat frequency length using a p-emf sensor

The coherence of light is essential for understanding interference phenomena, which are pivotal in a wide range of applications. However, due to the technical challenges of conventional methods, quantifying coherence is difficult to achieve in undergraduate optics laboratories. In this work, we present a modification of a method and experimental setup that can enhance the understanding of coherence concepts employing a sensor based on the non-steady-state photo-electromotive force (p-emf) effect. This p-emf sensor generates an electrical current proportional to the square of the interference pattern’s visibility, eliminating the need for image processing and high-quality optical elements, and allowing for real-time measurements. We demonstrated the method by measuring the coherence length of a He-Ne laser and the corresponding length associated with the beat frequency of the laser cavity’s longitudinal modes. This approach is robust, straightforward and simple, making it suitable for implementation in undergraduate optics laboratories.

Characterization of microbubble cavitation in theranostic ultrasound-mediated blood-brain barrier opening for gene delivery.

Characterization of microbubble cavitation in theranostic ultrasound-mediated blood-brain barrier opening for gene delivery.

Commercial fishing influences the life histories of fish in the world's largest desert lake.

Lake Turkana, the world's largest permanent desert lake, is an important source of fish for both local consumption and international trade. The growth of Lake Turkana's commercial fishery has increased the risk of overexploiting the lake's fish stocks. Selection pressure from overexploitation of fish stocks often drives shifts in fish life-history traits, including mean length (Lmean), maximum length (Lmax) and size at maturity (Lmat). To assess the life-history indicators of overexploitation in Lake Turkana, we compared the life-history traits of six of Lake Turkana's major commercial fish species from three time periods (1930-1953, 1972-1975, 2010-2022) that represent distinct levels of fishing pressure. These focal species were the African butter catfish Schilbe uranoscopus Rüppell 1832, the elongate tigerfish Hydrocynus forskahlii (Cuvier 1819), Nile perch Lates niloticus (L. 1758), Nile tilapia Oreochromis niloticus (L. 1758), silversides Alestes baremose (Joannis 1835) and wahrindi Synodontis schall (Bloch and Schneider 1801). Heavily exploited species exhibited notable decreases in Lmat as fishing pressure increased, and include A. baremose (29.7% decrease), H. forskahlii (16.4% decrease), L. niloticus (56.1% decrease) and O. niloticus (45.3% decrease). In contrast, lightly exploited species, including S. uranoscopus and S. schall, did not exhibit large declines in life-history traits. Additionally, we used current catch length frequency data for L. niloticus to infer that L. niloticus are currently experiencing overfishing and exhibit signs of the depletion of large 'mega-spawners'. These results suggest that heavy commercial fishing likely drives the observed life-history responses. We suggest that the management of sustainable fisheries in Lake Turkana should focus on gear size restrictions as well as on reducing fishing effort on commercial-sized fish to decrease the probability of overfishing and potential declines of stocks.

Stock Assessment of Long Whisker Catfish (Mystus gulio): Ensuring the Fisheries’ Sustainability in the Sundarbans Mangrove, Bangladesh

The world’s largest mangrove, Sundarbans, Bangladesh, is the habitat of the euryhaline catfish Nona Tengra (Mystus gulio). This study aimed to assess the stock status of M. gulio and provide reference points for sustainable fisheries’ management. One-year length–frequency (LF) data were collected from the Sundarbans region of Bangladesh and analyzed using the Length-Based Bayesian Biomass (LBB) method and the Length-Based Spawning Potential Ratio (LBSPR) model. The findings showed healthy biomass (B/BMSY = 1.2), with 57% of the wild stock of this species being harvested (B/B0 = 0.43). The calculated fishing mortality ratio indicated the underfishing conditions (F/M = 0.9). Safe exploitation (E = 0.46) was depicted, as E was smaller than the permitted level of 0.5. The value of capture length (Lc = 12.8 cm) was larger than the optimum capture length (Lc_opt = 10.0 cm) and the optimum length for maximum yield per recruit (Lopt = 12.0 cm) and larger than the maturity length (Lm = 9.16 cm), indicating the capture of mature individuals. The calculated Spawning Potential Ratio (SPR = 48%) was higher than the target reference points (SPR = 40%). This research evaluated the sustainable stock status. Although the margin between Lc_opt and Lm is very narrow, setting the minimum capture size at Lopt would be a conservative buffer to ensure long-term sustainability. The recommended minimum harvest size is 12 cm for M. gulio. Current fishing gear selectivity can ensure the sustainability of M. gulio in Sundarbans, Bangladesh; however, maintaining current fishing practice through careful management is suggested. Further assessments with length-based and other low-data methods should be conducted to refine exploitation estimates and trends.

Assessment of Growth and Mortality Parameters of Four Commercial Fish Species from Lekki Lagoon Nigeria

This study assessed the growth and mortality parameters of four commercial fish species (Chrysichthys ni-grodigitatus (Lacepède, 1803), Coptodon zillii (Gervais, 1848), Ethmalosa fimbriata (Bowdich, 1825) and Elops lacerta (Valenciennes, 1847) from Lekki Lagoon, Nigeria. Fish specimens were collected monthly from five landing sites (Wharf, Agbalegiyo, Ebute-Oni, Ilumofin and Luboye). Specimens were collected us-ing proportional sampling based on the level of fishing activities between January and December, 2022. Es-timation of growth parameters was performed according to the growth equation: Lt = L∞- (1- e-K(t-to)) by von Bertalanffy with the Length Frequency Data Analysis (LFDA) package. The length-converted catch curve model was adopted for the estimation of mortality parameters using FiSAT II software. Results showed that C. nigrodigitatus exhibited the highest growth rate (K = 1.30 yr⁻¹) and exploitation rate (E = 0.83) with an as-ymptotic length (L∞) of 53.94 cm. However, C. zillii exhibits the lowest growth curvature (K = 0.44 yr⁻¹) with L∞ = 39.15 cm and an exploitation rate of 0.42. E. fimbriata showed a rapid growth rate (K = 1.15 yr⁻¹) but low exploitation (E = 0.12), while E. lacerta exhibited moderate growth rate (K = 0.58 yr⁻¹) and low exploita-tion (E = 0.16). It is concluded that C. nigrodigitatus is overfished in the lagoon, which demands a closed season and small mesh size restriction to prevent recruitment overfishing. The low exploitation levels of E. fimbriata and E. lacerta means that these stocks are currently sustainable, but there is a need to monitor them to avoid future over-exploitation.

Population parameters and the stock status in Sardinella maderensis (Lowe, 1838) in the coastal waters of Côte d’Ivoire (West Africa)

In West Africa, many fisheries are fully exploited or overexploited. The primary challenge in addressing this issue is often the lack of data to inform management policies. Since 2011, the production of Sardinella maderensis has been declining, and data on the species’ population dynamics are scarce. This study aims to examine the population dynamics of S. maderensis and provide preliminary data on the state of its stock within the coastal waters of Côte d’Ivoire. Such data are essential for the sustainable management of these fisheries. To achieve this objective, a total of 2,112 samples of S. maderensis were collected from April 2022 to March 2023. These samples were measured for total lengths and analyzed using FiSAT II software. The length frequency distribution ranged from 12 to 41 cm, with an average of 23.03 ± 19.09 cm. The asymptotic length (L∞) was 31.50 cm, the growth rate (K) was 0.68 year⁻¹, the growth performance index (Φ’) was 2.82, and the theoretical age (t0) was -0.105 year, indicating that this species is fast-growing. S. maderensis in the coastal waters of Côte d’Ivoire reaches sexual maturity before being caught by fishing gear, suggesting that the catches predominantly consist of mature individuals. The exploitation rate (E) was recorded at 0.47, slightly higher than the E max value. The study concludes that S. maderensis is overexploited in the coastal waters of Côte d’Ivoire. These findings should inform the adoption of appropriate measures for the sustainable management of this species, particularly by reducing fishing effort through regulating this fishery.

Effect of the tapeworm Ligula pavlovskii on the life-history of the alien monkey goby (Neogobius fluviatilis)

The life-history traits of fish are influenced by numerous factors, including parasitic infections. Parasites can significantly impact host mortality, growth performance, and reproductive success. This study examines the effects of the parasite Ligula pavlovskii (Diphyllobothriidae) on its host, the monkey goby (Neogobius fluviatilis), in Lake Balaton, Hungary. Both species originated in the Ponto-Caspian region, with the fish arriving in the 1970s and the parasite following in the 2000s. Our research reveals substantial impacts of L. pavlovskii on the life history of the monkey goby, including differences in somatic (condition, length) and reproductive (gonadosomatic index, fecundity, egg size) investments between infected and non-infected individuals. Condition declined with higher parasite index in infected individuals. Female GSI was influenced by both parasite presence and severity of the infection, whereas male GSI was affected by the presence of the parasite. Additionally, the length frequency distributions of infected and non-infected fish showed seasonal differences, due to the bigger body size of infected individuals in summer and autumn. The high prevalence of the parasite and associated mortality resulted in a significantly reduced expected lifespan for infected fish. Our findings suggest that the competitive advantage of N. fluviatilis may be reduced when this fish is infected by L. pavlovskii. This should be considered when developing management interventions for this species.

Genetic evidence for a fall-spawning group of Gulf sturgeon (Acipenser oxyrinchus desotoi) in the Apalachicola River, Florida, USA

The Gulf sturgeon (Acipenser oxyrinchus desotoi) is a large, long-lived, anadromous fish inhabiting the northern Gulf of Mexico. This charismatic fish was hunted to near extinction in the early 1900s. In 1991 the subspecies was listed as threatened under the Endangered Species Act. Recovery continues to be challenged by threats such as habitat destruction, fisheries bycatch, and climate change. There are seven known natal rivers. Historically, each river was thought to contain a single, spring-spawning group. Recent studies have discovered several rivers (Suwannee, Choctawhatchee) contain a second, fall-spawning group. This study utilizes genetic techniques to investigate the proposed existence of a fall-spawning group in the Apalachicola River, Florida. Juvenile Gulf sturgeon were sampled between May and July, from 2013 to 2022. Four adults were also captured on the spawning grounds during October of 2022. Samples were genotyped for thirteen microsatellite loci to assess genetic population structure within the Apalachicola River. Analyses detected two distinct genetic groups (FST = 0.085). Dates of capture, length frequency distributions of juveniles, and genetic assignment of spawning adults allowed us to characterize these as separate spring- and fall-spawning groups. While approximately 90% of juveniles collected were assigned to the spring, only slight differences in genetic diversity were detected between groups. The temperature window for spawning was found to be three weeks shorter on average in the fall than the spring, highlighting the need for additional research into differing environmental or anthropogenic influences on these populations. The discovery of a fall-spawning group of Gulf sturgeon in the Apalachicola River improves our understanding of the representation, redundancy, and resiliency of the species and provides critical information for improved management of this river system.

Genetic evidence for a fall-spawning group of Gulf sturgeon (Acipenser oxyrinchus desotoi) in the Apalachicola River, Florida, USA.

The Gulf sturgeon (Acipenser oxyrinchus desotoi) is a large, long-lived, anadromous fish inhabiting the northern Gulf of Mexico. This charismatic fish was hunted to near extinction in the early 1900s. In 1991 the subspecies was listed as threatened under the Endangered Species Act. Recovery continues to be challenged by threats such as habitat destruction, fisheries bycatch, and climate change. There are seven known natal rivers. Historically, each river was thought to contain a single, spring-spawning group. Recent studies have discovered several rivers (Suwannee, Choctawhatchee) contain a second, fall-spawning group. This study utilizes genetic techniques to investigate the proposed existence of a fall-spawning group in the Apalachicola River, Florida. Juvenile Gulf sturgeon were sampled between May and July, from 2013 to 2022. Four adults were also captured on the spawning grounds during October of 2022. Samples were genotyped for thirteen microsatellite loci to assess genetic population structure within the Apalachicola River. Analyses detected two distinct genetic groups (FST = 0.085). Dates of capture, length frequency distributions of juveniles, and genetic assignment of spawning adults allowed us to characterize these as separate spring- and fall-spawning groups. While approximately 90% of juveniles collected were assigned to the spring, only slight differences in genetic diversity were detected between groups. The temperature window for spawning was found to be three weeks shorter on average in the fall than the spring, highlighting the need for additional research into differing environmental or anthropogenic influences on these populations. The discovery of a fall-spawning group of Gulf sturgeon in the Apalachicola River improves our understanding of the representation, redundancy, and resiliency of the species and provides critical information for improved management of this river system.

Do speed amplitude and period affect gait variability and step followability under sinusoidal speed changing conditions?

The time courses of the joint elevation angles of the thigh, shank, and foot in one stride during walking can be well approximated by a "plane" in a triaxial space. This intersegmental coordination (IC) of the lower limb elevation angles is associated with gait variability. This study aimed to examine how anteroposterior and lateral gait variabilities are influenced by different amplitudes (±0.33 vs. ± 0.67 m·s-1) and periods (30 vs. 60 s) of sinusoidal speed changes. We also examined which limbs are responsible for the step variabilities. The IC plane thickness and coefficient of variance of step width (CVSW) were quantified as anteroposterior and lateral gait variability in 18 young adults. Time delay of step length (TDSL) and step frequency (TDSF) against sinusoidal speed changes were determined. Two-way statistical parametric mapping was applied for the time courses of each limb angle. The IC plane thickness was greater in the ±0.67 m·s-1 condition than the ±0.33 m·s-1 condition. Neither periods nor amplitudes affected CVSW, TDSL, and TDSF. In the middle gait cycle, shank and foot angles were delayed against sinusoidal speed changes in the ±0.67 m·s-1 condition during acceleration phase, whereas shank and thigh angles proceeded in that condition during deceleration phase. Amplitude of sinusoidal speed changes increased anteroposterior, but not lateral, gait variability regardless of period. Distal and proximal limbs are controlled differently when continuous step adjustments are required, and this may be attributed to step variabilities.

Stock Status of Skipjack Tuna (Katsuwonus pelamis Linnaeus, 1758) using Length-Based Assessment in Cenderawasih Bay, Indonesia

The West Pacific and the waters of Cenderawasih Bay are potential fishing grounds and part of the fishery management area (FMA) 717 of the Republic of Indonesia. Increased production demand may result in overfishing, which has led to the depletion of fish stocks. To ensure the long-term viability of these fisheries, effective management practices are essential. This study aims to examine size distribution, growth, and population parameters that can be used as fish resource management inputs for skipjack fisheries in Cenderawasih Bay. Length-based approach was used to estimate biological parameters and the dynamics of populations as well as the stock status within data-limited fisheries. Length frequency data was used to assess the Katsuwonus pelamis fisheries condition. From January to November 2021, in all of 2,211 fish were taken samples from numerous commercial small-scale vessel units that were operating around anchor fish aggregating devices (FADs). The results showed that the exploitation rate (E) was 0.69 year1, L ∞ = 96.8 cm fork length (cmFL), k= 0.38 year-1, and t0 = -0.31 year. Natural mortality (M) was 0.66 year-1, fishing mortality (F) was 1.46 year-1, and total mortality (Z) was 2.12 year-1. Overfishing condition has occurred according to the current fishing mortality rate (Fcur=1.46 year-1), which has exceeded the reference point of maximum fishing mortality (Fmax=0.76 year-1) and F40% (0.9 year-1). The growth overfishing condition was indicated based on the current selectivity of handline (Lccur=42 cm), which is smaller than the optimal selectivity of Lmax (55 cm). Some management tools, such as the regulation on minimum size of hooks and the total allowable catch (TAC) system, can be utilized to consider skipjack tuna fisheries sustainability in Cendrawasih Bay.

A linguistic comparison between ChatGPT-generated and nonnative student-generated short story adaptations: a stylometric approach

The present study provides a qualitative-quantitative linguistic analysis of AI-generated versus human-generated short story adaptations with the aim of detecting the stylometric features that distinguish each style. The author analyzed 15 classic short story adaptations written by nonnative ESL students in an Egyptian university and compared them to 15 adaptations of the same short stories generated by the AI bot, ChatGPT, in terms of content as well as the stylometric language features of length, lexical choices and word frequencies. The results show that the AI-generated text was more loyal to the main theme, plot line and character description of the original story but used language that was more complex, descriptive, unique and bias-free, whereas the student-generated text deviated from the original story in terms of theme, plot, characters and context and used language structures that were simpler and more repetitive. The non-native features characterizing student-generated text included long sentences with excessive use of coordinators, basic vocabulary, frequent intensifiers and L1-induced structures and sociocultural stereotypes. The implications of the study can be used to inform the ESL community of ways to distinguish ChatGPT-generated from nonnative human-generated linguistic features with the aim of attributing texts to their rightful authors as well as finding out the linguistic and stylistic features that characterize non-native English text.

INFLUENCE OF BACKPACK LOAD ON POSTURE AND GAIT BIOMECHANICS IN SCHOOL-AGED CHILDREN

Background: School-aged children frequently carry backpacks that exceed safe weight limits, placing them at risk of postural deviations and altered gait mechanics. International guidelines recommend that backpacks should not exceed 10–15% of a child's body weight, yet students in Pakistan, particularly in urban areas like Lahore, often carry loads beyond this range. This can lead to forward trunk inclination, spinal misalignment, shoulder asymmetry, and compromised gait, ultimately affecting musculoskeletal development and physical wellbeing. Objective: To evaluate the impact of varying backpack weights on postural alignment and gait biomechanics in school-going children using the Posture and Postural Ability Scale (PPAS). Methods: A cross-sectional study was conducted from August 2024 to January 2025 across five public and private schools in Lahore. A total of 200 children aged 8–14 years were selected using stratified random sampling. Participants were divided into three groups based on backpack weight as a percentage of body weight: Light Load (<10%), Moderate Load (10–15%), and Heavy Load (>15%). Postural assessments were performed using the PPAS, which scores from 1 (normal) to 7 (severe deviation). Gait parameters, including stride length (cm), walking speed (m/s), and step frequency (steps/min), were recorded. Data were analyzed using SPSS v25, with significance set at p < 0.05. Results: Students in the Heavy Load group demonstrated significantly higher forward trunk lean (5.2 ± 1.1), shoulder asymmetry (6.1 ± 1.4), and postural instability (5.6 ± 1.3) compared to the Light Load group (1.8 ± 0.9, 2.1 ± 0.7, and 1.9 ± 0.8, respectively; p = 0.000). Stride length decreased from 55.3 ± 4.2 cm to 45.8 ± 6.0 cm, walking speed reduced from 1.2 ± 0.2 m/s to 0.8 ± 0.1 m/s, and step frequency dropped from 110 ± 5 to 98 ± 6 steps/min in Heavy Load group (p = 0.000). Conclusion: Excessive backpack weight significantly affects postural control and gait biomechanics in children, increasing the risk of long-term musculoskeletal complications. The PPAS proved effective in detecting postural deviations. School-based interventions and ergonomic guidelines are critical to mitigate these risks.

Stock Status of the Moonfish (Citharinus citharus) for Management Strategies and Conservation in Oguta Lake, Imo State, Nigeria

The fisheries stock status of Citharinus citharus in Oguta Lake was investigated from September 2023 to April 2024. Assorted fishing gears were deployed to catch fish. The standard lengths in centimeters (cm) of 32,748 specimens of C. citharus were measured. The length data were analyzed with Electronic Length Frequency II (ELEFAN II) and fitted into the Von Bertalanffy Growth Model (VBGM). The VBGM was L(t) = 62.85[1 – e -0.165(t – 0.87)]. Total Mortality (Z) = 2.297yr-1, Fishing Mortality (F) = 1.86yr-1, Natural Mortality (M) = 0.45yr-1 and Exploitation rate (E) = 0807yr-1. Length at first sexual maturity (Lm) = 41.9cm. C. Citharus is experiencing overexploitation and overfishing in Oguta Lake. Conservation and Management strategies should include restrictions on the use of small mesh sizes that would reduce the catching of sexually immature individuals (of Length ≤ 41.9cm) and the closure of the fishing Season of C citharus from July to September annually.

The Influence of Pruning on the Growth and Wood Properties of Populus deltoides “Nanlin 3804”

During the natural growth of trees, a large number of branches are formed, with a negative impact on timber quality. Therefore, pruning is an essential measure in forest cultivation. In this work, the effect of pruning on poplar timber quality was evaluated. This study used an artificial forest of Populus deltoides “Nanlin 3804”, established in 2014, as the research object. Pruning was carried out in March 2018 and March 2020 with a pruning intensity of one-third, and a control group was also set up. In December 2023, the growth of 11-year-old poplars under different treatments was investigated and analyzed, and sample trees were cut down for a wood property analysis. The results showed that pruning did not have a significant effect on the growth of the diameter at breast height, the tree height, or the volume. However, pruning could significantly facilitate the forming of higher-quality timber with smaller knots. Compared to unpruned wood, the ring width decreased 1–2 years after pruning, while it turned out to be greater than that of the control 3 years after pruning. Moreover, pruning can reduce the degree of trunk tapering. The fiber aspect ratio two years after pruning was greater than that of the control. The distribution frequency of fiber lengths of between 1500 μm and 1900 μm and that of fiber widths of between 32 μm and 38 μm were higher than that of the control. However, pruning had little effect on their density and oven-dried shrinkage. In addition, compared to the control, the bending strength and the modulus of elasticity increased by approximately 11%–14%, the impact toughness decreased by approximately 5%, and the compressive strength increased by approximately 6%. Pruning proved to be a successful method to improve the timber quality.

Assessment of Three Fish Species Stock for Conservation and Management Policy in River Imo, Nigeria

The rates of Growth, recruitment, mortality, and exploitation of three important fish species of the River Imo, Nigeria, were investigated, aimed at providing information on their conservation status and management policies for their sustainability. These species are big-sized and fleshy, and they are Gymnarchus niloticus (Cuvier 1829), Clarias gariepinus (Burchell 1822) and Distichodus notratus (Gunther 1864). Assorted fishing gears were used to catch the species fortnightly from January to July 2023, and data on their standard length were taken to the nearest centimeter (cm). 503,129 specimens were examined and measurements analyzed with the Electronic Length Frequency Analysis (ELEFAN II) fitted into the von Bertalanffy Growth Model (VBGM) of L(t) = L∞ [1 – e –k(t-t0)] with FAOICLARM (FISAT) tools software. Asymptotic length (L∞) for G. niloticus = 210cm, C. gariepinus = 94.50 cm and D. rostratus = 68.25cm. Comparing the stock parameters of total mortality (Z), Fishing Mortality (F), Exploitation rate (E) and length of sexual maturity (Lm), G. niloticus was observed to be over-exploited (E = 0.84), D. rostratus was near optimal level of exploitation (E = 0.51) while C. gariepinus was not over- exploited (E = 0.24). Recommended management policies are restriction on the use of small mesh sizes (≤ 3 cm); prohibition of the catches of sexually immature individuals (for G. niloticus sizes ≤ 140.0 cm, C. gariepinus ≤ 63.0cm and D. rostratus ≤ 45.5 cm) and enforcement of closed fishing season on the observed peak of recruitment: April – May – June – July in River Imo.

Evaluation of Low-Coverage Sequencing Strategies for Whole-Genome Imputation in Pacific Abalone Haliotis discus hannai.

Low-coverage whole-genome sequencing (lcWGS) followed by imputation is emerging as a cost-effective method for generating a substantial number of single nucleotide polymorphism (SNP) in aquatic species with highly heterozygous and complex genomes. This study represents the first systematic investigation into the application of low-coverage whole-genome sequencing (lcWGS) combined with imputation for genotyping in Pacific abalone (Haliotis discus hannai) without a reference panel. We utilized 1059 Pacific abalone individuals sequenced at an average depth of 7.86×, as well as 16 individuals sequenced at 20×, as sample materials. To assess the genotype imputation accuracy for lcWGS without a reference panel, we simulated data with varying sequencing depths (0.5-4×) and examined the effects of sample size, chromosome length, and minor allele frequency (MAF) using BaseVar and STITCH strategies. Results showed that STITCH achieved high accuracy when the sample size exceeded 400, with a genotype correlation (R2) of 0.98 ± 0.002 and genotype concordance (GC) of 0.99 ± 0.001. Imputation accuracy plateaued when the sample size exceeded 400 and sequencing depth surpassed 1×. Chromosome length had minimal effects, with all three chromosomes achieving an accuracy of approximately 0.98. However, the accuracy for rare MAF (<0.05) was lower, falling below 0.99. A second imputation with Beagle significantly increased SNP detection by 3.9-8.3 folds for a sequencing depth of 0.5-4×, apparently without sacrificing accuracy. To our knowledge, this is the first study of lcWGS analysis conducted in abalone. The findings demonstrate that lcWGS with imputation can achieve high accuracy with moderate sample sizes (n ≥ 400) in Pacific abalone, offering a cost-effective approach for genotyping in aquaculture species.

Investigating the effect of experience sampling study design on careless and insufficient effort responding identified with a screen-time-based mixture model.

When using the experience sampling method (ESM), researchers must navigate a delicate balance between obtaining fine-grained snapshots of phenomena of interest and avoiding undue respondent burden, which can lead to disengagement and compromise data quality. To guide that process, we investigated how questionnaire length and sampling frequency impact careless and insufficient effort responding (C/IER) as an important yet understudied aspect of ESM data quality. To this end, we made use of existing experimental ESM data (Eisele et al., 2022) from 163 students randomly assigned to one of two questionnaire lengths (30/60 items) and one of three sampling frequencies (3/6/9 assessments per day). We employed a novel mixture modeling approach (Ulitzsch, Nestler, et al., 2024) that leverages screen time data to disentangle attentive responding from C/IER and allows investigating how the occurrence of C/IER evolved within and across ESM study days. We found sampling frequency, but not questionnaire length, impacted C/IER, with higher frequencies resulting in higher overall C/IER proportions and sharper increases of C/IER across, but not within days. These effects proved robust across various model specifications. Further, we found no substantial relationships between model-implied C/IER and other engagement measures, such as self-reported attentiveness, attention checks, response-pattern-based attentiveness indicators, and compliance. Our findings contrast previous studies on noncompliance, suggesting that respondents may employ different strategies to lower the different types of burden imposed by questionnaire length and sampling frequency. Implications for designing ESM studies are discussed. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Spatiotemporal and kinetic characteristics during maximal sprint running in fast running soccer players.

This study aimed to elucidate spatiotemporal and kinetic variables in fast-running soccer players in comparison with sprinters or slow-running soccer players. Sixty-seven male soccer players and 17 male sprinters (Sp) performed 60-m maximal effort sprint running. The soccer players were classified into three groups: high-speed (SOCHigh), medium-speed, and low-speed (SOCLow). The antero-posterior and vertical ground reaction forces were measured with a 50-m long force plates system at every step during the sprint. Step length and step frequency were also computed from the position of center of pressure, contact time, and flight time. During the initial acceleration phase, SOCHigh exhibited similar running speeds to Sp. This was attributed to a higher step frequency in SOCHigh compared to Sp, while net antero-posterior impulse was lower in the former than in the later. In the range of running speed from 7.5 m/s to 8.5 m/s, net antero-posterior impulse for SOCHigh was similar to that for Sp. At 9.0 m/s, SOCHigh exhibited a lower net antero-posterior impulse compared to Sp, primarily due to a reduced propulsive impulse. Additionally, vertical impulse during the braking phase was larger in SOCHigh compared to Sp, due to a longer braking time, while vertical impulse during the propulsive phase was smaller, due to a tendency for a reduced propulsive time and vertical force during the corresponding phase. Compared to SOCLow, SOCHigh exhibited higher step frequency through sprint running and longer step lengths from the 2nd acceleration phase to maximal speed phase. Additionally, net antero-posterior impulse at the same running speed was greater in SOCHigh compared to SOCLow. Vertical impulse was lower during the braking phase but higher during the propulsive phase in SOCHigh than in SOCLow. Thus, the sprint mechanics of SOCHigh is characterized by a similar ability of speed acquisition up to the 2nd acceleration as sprinters. However, at 9.0 m/s or over, SOCHigh exhibits a greater vertical impulse, leading to a lower step frequency.

Spontaneous Emission of Internal Waves by a Radiative Instability

Abstract The spontaneous emission of internal waves (IWs) from balanced mesoscale eddies has been previously proposed to provide a source of oceanic IW kinetic energy (KE). This study examines the mechanisms leading to the spontaneous emission of the spiral-shaped IWs from an anticyclonic eddy with an order-one Rossby number, using a high-resolution numerical simulation of a flat-bottomed, wind-forced, reentrant channel flow configured to resemble the Antarctic Circumpolar Current. It is demonstrated that the IWs are spontaneously generated as a result of a loss of balance process that is concentrated at the eddy edge and then radiates radially outward. A 2D linear stability analysis of the eddy shows that the spontaneous emission arises from a radiative instability which involves an interaction between a vortex Rossby wave supported by the radial gradient of potential vorticity and an outgoing IW. This particular instability occurs when the perturbation frequency is superinertial. This finding is supported by a KE analysis of the unstable modes and the numerical solution, where it is shown that the horizontal shear production provides the source of the perturbation KE. Furthermore, the horizontal length scale and frequency of the most unstable mode from the stability analysis agree well with those of the spontaneously emitted IWs in the numerical solution. Significance Statement Spontaneous emission of internal waves (IWs) describes a process by which large-scale, slow oceanic currents can spontaneously emit IWs. Recent observations and numerical studies suggest that spontaneous IW emission can provide an important IW energy source. Identifying the mechanisms responsible for spontaneous IW emission is therefore of utmost importance because IW breaking has crucial effects on the oceanic large-scale circulation. This study examines the spontaneous emission of IWs from a numerically simulated anticyclonic eddy. We show that the emission process results from radiative instability when the perturbation frequency is larger than the Coriolis frequency. This instability mechanism can be significant across the oceans for flow structures with order-one Rossby numbers (a measure of flow nonlinearity).