Search Results (263)

Lorentz invariance is such a basic principle in fundamental physics that it must be constantly tested and any proposal of its violation and breakdown of CPT symmetry that might characterize some approaches to quantum gravity should be treated with care. In this review, we examine, among other scenarios, such instances in supercritical (Liouville) string theory, particularly in some brane models for “quantum foam”. Using the phenomenological formalism introduced here, we analyze the observational hints of Lorentz violation in time-of-flight lags of cosmic photons and neutrinos which fit excellently stringy space–time foam scenarios. We further demonstrate how stringent constraints from other astrophysical data, including the recent first detections of multi-TeV events in $\gamma$-ray burst 221009A and PeV cosmic photons by the Large High Altitude Air Shower Observatory (LHAASO), are satisfied in this context. Such models thus provide a unified framework for all currently observed phenomenologies of space–time symmetry breaking at Planckian scales. Full article

Background/Objectives: Frailty is a multifactorial condition influenced by physical and psychosocial factors. Understanding longitudinal changes in these domains may guide prevention strategies. This study examines the relationship between frailty status, physical fitness, and psychosocial conditions in community-dwelling older adults using five-year longitudinal data. Methods: Participants were 52 out of 89 older adults who completed both baseline and five-year follow-up assessments (follow-up rate: 58.4%). Data were collected using 10 physical fitness indicators, the fitness age score (FAS), geriatric depression scale (GDS), Lubben social network scale short form (LSNS-6), and relevant items in the six Kihon Checklist (KCL) domains. Due to low prevalence of frailty, individuals with pre-frailty and frailty were combined into the frailty-risk group. Repeated measures ANOVA with sex as a covariate was conducted to compare groups. Logistic regression was used to identify baseline predictors of frailty status at five years. Statistical significance was set at p < 0.05. Results: GDS, LSNS-6, and KCL scores remained stable over five years. However, physical fitness significantly declined in several measures, including grip strength, vertical jump height, knee extension strength, functional reach, and FAS. A significant interaction for the timed up and go test showed that the robust group maintained function, while the frailty-risk group declined. Logistic regression identified KCL oral function as a significant predictor (OR = 5.331, 95% CI = 1.593–17.839, p = 0.007). Conclusions: Maintaining both oral function and physical fitness is vital for preventing frailty, even among health-conscious older adults. Proactive strategies may support healthy aging. Full article

The Sylhet Division of Bangladesh, highly susceptible to monsoon flooding, requires effective flood risk management to reduce socio-economic losses. Flood frequency analysis is an essential aspect of flood risk management and plays a crucial role in designing hydraulic structures. This study applies regional flood frequency analysis (RFFA) using L-moments to identify homogeneous hydrological regions and estimate extreme flood quantiles. Records from 26 streamflow gauging stations were used, including streamflow data along with corresponding physiographic and climatic characteristic data, obtained from GIS analysis and ERA5 respectively. Most stations showed no significant monotonic trends, temporal correlations, or spatial dependence, supporting the assumptions of stationarity and independence necessary for reliable frequency analysis, which allowed the use of cluster analysis, discordancy measures, heterogeneity tests for regionalization, and goodness-of-fit tests to evaluate candidate distributions. The Generalized Logistic (GLO) distribution performed best, offering robust quantile estimates with narrow confidence intervals. Multiple Non-Linear Regression models, based on catchment area, elevation, and other parameters, reasonably predicted ungauged basin peak discharges (R² = 0.61–0.87; RMSE = 438–2726 m³/s; MAPE = 41–74%) at different return periods, although uncertainty was higher for extreme events. Four homogeneous regions were identified, showing significant differences in hydrological behavior, with two regions yielding stable estimates and two exhibiting greater extreme variability. Full article

The relative age effect (RAE) refers to the advantage often observed in sports selection processes, where athletes born earlier in the calendar year are favored over those born later. While the RAE has been widely studied in various sports, little is known about its presence in rhythmic gymnastics (RG), a female-dominated esthetic sport characterized by early specialization. This study investigated the presence of the RAE among elite rhythmic gymnasts (RGs) at the international level, focusing on differences in birth quarter distribution across age categories and performance levels. The sample included 578 RGs—356 juniors and 222 seniors—competing in individual and group events. Birthdates were categorized into four quartiles (Q1–Q4). Chi-square goodness-of-fit tests and standardized residuals as post hoc tests were used to analyze the RAE. No significant RAE was found in the overall sample or when analyzed by geographic region (p > 0.05). However, a significant under-representation in Q4 occurred for Group RGs (SR = −2.17), and among all juniors (SR = −2.54) (χ²[3, 356] = 9.833, p < 0.05, w = 0.17), particularly in the subgroup of 15-year-old gymnasts, who were over-represented in Q3 (SR = 2.55; χ²[3, 183] = 10.027, p < 0.05, w = 0.23). Finalists—especially those in group events—also showed a higher proportion of Q3 athletes and a lower proportion of those born in Q4. Among junior finalists, Q4 was significantly under-represented (p < 0.05). These novel sport-specific findings suggest the presence of an atypical RAE pattern in RG, particularly in younger age groups and among high-performing athletes. RG coaches and policymakers should consider alternative selection models and adapt training approaches for Q4-born gymnasts in order to prevent early deselection. Full article

Over the past two decades, substantial efforts have been made to develop survival models for gap times between recurrent events. An emerging approach involves considering rate models derived from a non-homogeneous Poisson process, thus allowing the conditional distribution of a gap time given the previous recurrence time to be deduced. Under this approach, some parametric rate models have been proposed, differing in their distributional assumptions on gap times. In particular, the extended exponential–Poisson, Weibull and extended Chen–Poisson distributions have been considered. Alternatively, a flexible rate model using restricted cubic splines is proposed here to capture complex non-monotonic rate shapes. Moreover, a comprehensive comparison of parametric rate models is presented. The maximum likelihood method is applied for parameter estimation in the presence of right-censoring. It is shown that some models include important special cases that allow testing of the independence assumption between a gap time and the previous recurrence time. The likelihood ratio test, as well as two information criteria, are discussed for model selection. Model fit is assessed using Cox–Snell residuals. Applications to two well-known clinical data sets illustrate the comparative performance of both the existing and proposed models, as well as their practical relevance. Full article

Background: CrossFit^® aims to be equitable between both males and female athletes, supporting equal representation and equal prize money at international events. However, to date, limited information is known on CrossFit^® athletes’ performance in the countermovement jump (CMJ), countermovement rebound jump (CMR-J), and isometric mid-thigh pull (IMTP) when assessed using force plates, and if there are any differences between sexes. Therefore, the purpose of the present study was to observe whether any sex-based differences and relationships exist between performance within these assessments. Methods: A total of CrossFit athletes (43 male = 32.8 ± 9.0 years; height 1.78 ± 0.06 m; mass = 92.4 ± 10.6 kg; and 31 female = 31.0 ± 7.6 years, height = 1.64 ± 0.05 m; mass = 68.8 ± 6.0 kg) completed three trials of CMJ, CMR-J and IMTP using portable dual-system force-plate sampling at 1000 Hz. Results: Moderate–large relationships were observed between CMJ, CMR-J and IMTP outcome measures (r = 0.396–0.809, p < 0.001). Males demonstrated small to moderately greater performance outcomes than females for CMJ height (males = 0.35 ± 0.08 m; females 0.30 ± 0.06 m, d = 0.73), CMR-J height (males = 0.32 ± 0.08 m; females = 0.30 ± 0.06 m, d = 0.39) and IMTP peak net force (males = 30.62 ± 10.01 N·kg⁻¹; females = 27.49 ± 6.44 N·kg⁻¹, d = 0.29). Conclusions: Maximal relative strength in CrossFit^® athletes should be seen as imperative in both male and female athletes due to the meaningful relationship in ballistic and plyometric ability. Moreover, previous relationships with CrossFit^® performance and the injury risk reduction benefits of improving strength provide further support. The descriptive data presented could be used by CrossFit^® coaches to assess and compare the current performance of their own athletes in a battery of tests examining CMJ, CMR-J and IMTP, while also facilitating decisions upon prescription within training and competition. Full article

Zhejiang Province in China is one of the most typhoon-prone regions globally, making typhoon and storm surge hazard analysis critically important for disaster mitigation. This study integrates the Tropical Cyclone Risk Model (TCRM) with a machine learning-based storm surge forecasting model to analyze typhoon hazards and storm surge risks at four representative coastal sites in Zhejiang Province: Haimen, Ruian, Wenzhou, and Zhapu. Firstly, the input database of the TCRM has been updated and subsequently used to generate a 1000-year synthetic typhoon event catalog for the Northwest Pacific region. Secondly, four machine learning models—Long Short-Term Memory (LSTM), Back Propagation (BP), Support Vector Regression (SVR), and Random Forest (RF)—were developed to forecast storm surge component at the four sites, with sensitivity analysis conducted on the input parameters. Among the four models, RF consistently outperformed the others across all four sites. Thirdly, by integrating the storm surge forecasting model with the Yan Meng (YM) typhoon wind field model, extreme wind speed sequences and extreme surge component sequences were derived for the four coastal sites. Finally, four extreme value distribution models—empirical distribution, Weibull, Gumbel, and Generalized Pareto Distribution (GPD)—were applied to fit the extreme wind and surge sequences. Goodness-of-fit tests indicated that the GPD best captured extreme wind speeds at all four sites and extreme surge levels at Haimen, Ruian, and Wenzhou. Using the optimal distributions, return periods (10-, 50-, 100-, and 200-year) for extreme wind speeds and surge components were calculated, providing actionable references for disaster risk management authorities. Full article

Background: The objective of our study was to investigate the impact of mineralocorticoid receptor antagonists (MRAs), such as spironolactone, administrated early after cardiac transplantation on the occurrence of acute graft rejection (AGR) in the first 2 years post-transplant. Methods: This retrospective research was conducted in the Emergency Institute for Cardiovascular Diseases and Transplantation of Targu Mures, Romania. After applying the inclusion criteria, between January 2011 and December 2023, 36 patients fit the study design. Using Cox proportional hazards regression and Kaplan–Meier curves, we determined the time-to-event distribution, for which the first episode of AGR was considered an event, with a significance threshold of 0.05. Results: The 1-year rate of AGR was 38.9% and was 47.2% at 2 years, with a 2-year mortality of 11.1%. The interpretation of the Cox regression indicated that early initiation of spironolactone represents a protective factor against the 2-year AGR (HR: 0.263; 95%CI: 0.076–0.922; p = 0.037 by the log-rank test). Conclusions: These results might suggest a possible benefit of the early administration of spironolactone after a heart transplant, but further prospective studies need to be performed for the validation of our findings. Full article

The working accuracy of space optical payloads, sensitive components, greatly depends on the pointing accuracy and stability of the platform. This article establishes a mathematical model for relative position and attitude measurement based on PSD and eddy current and analyzes the failure modes under the measurement models. Through model derivation, it can be concluded that the position and attitude measurement system has high redundancy; in the event of sensor failure in the horizontal or vertical direction, relative position and attitude measurement and resolution can still be completed, which solves the relative measurement problem of position and attitude measurement of the space Maglev vibration isolation control system, providing high-precision closed-loop control for the control system to achieve high-precision pointing and stability. In response to the requirements of high-precision non-contact displacement and attitude measurement, eddy current sensors were selected, and a sensor circuit box was designed. The testing and calibration system adopts an eight-bar Maglev layout, and the actuator has unidirectional dual-mode output. The actuator adopts a double closed magnetic circuit structure, and the coil adopts a winding single-coil structure. The system includes a multi-degree-of-freedom high-precision coil spatial pose automatic positioning platform, a strong magnetic structure, strong uniform magnetic field magnetization, an integrated assembly testing platform, etc. According to the test data, the driver has strong linearity in both low- and high-current ranges. The relative output error in the low-current range does not exceed 0.1 mA, and the relative output error in the high-current range does not exceed 2 mA. After fitting and calibration, it can meet the design requirements. Within redundant designing, fault mode analyzing, and system testing, the relative measurement system can ensure the working accuracy of the optical payload of the spacecraft, which reaches the advanced level in the field. Full article

In response to the current research status and existing problems of material distribution during major emergency events, we construct an intelligent emergency logistics route model based on cellular space AGNES clustering (AGglomerative NESting clustering) and a symmetrical fruit fly optimization algorithm. We establish the cellular algorithm based on urban road nodes and node local spaces, and construct the topology algorithm to implement the cellular space in a way that includes distribution centers and delivery points. In the cellular space, we develop an improved AGNES clustering algorithm based on the cellular space model in accordance with the neighboring relationship between distribution centers and delivery points, which quantifies the spatial clustering relationship between the distribution centers and the delivery points. Based on the clustering model, we construct an emergency logistics route model by using a symmetrical fruit fly optimization algorithm. In line with the symmetrical feature of a logistics route from one destination to another, the traveling distances within one route section are the same in both directions. Thus, we construct the logistics sub-intervals and logistics intervals by using distribution centers and delivery points, and the optimal fruit fly individuals and corresponding fitness functions are searched within the two-level intervals to obtain the emergency logistics routes with the lowest costs. Experimental results show that the proposed algorithm can output the optimal logistics routes for each logistics sub-interval and the entire logistics interval. Compared with the traditional route planning methods Dijkstra’s algorithm and the A* algorithm, it can reduce the cost of route planning and achieve optimization rates of 9.89% and 13.12%, respectively. The t-test proves that the constructed algorithm is superior to the traditional route planning algorithms in saving route costs. Full article

Background/Objectives: Osteoarthritis (OA) is a leading cause of mobility impairment in older adults, yet few studies have explored exergames (EXGs) as a complementary therapy for knee and/or hip OA (KOA/HOA). This study evaluated the effects of integrating EXGs into conventional therapy (CT) on functional mobility. Methods: Sixty participants were randomized into an EXG/CT group or a CT-only group. The interventions lasted 10 weeks (3 sessions/week), and the EXGs were selected from the interactive game Ring Fit Adventure (Nintendo Switch^®, Kyoto, Japan). Results: Functional mobility (Timed Up and Go test) significantly improved in the EXG/CT group but not in the CT group. Additionally, lower-limb strength and aerobic endurance increased in the EXG/CT group. No adverse events were reported, and the adherence was high. Conclusions: These findings support EXG-based interventions as a viable complement to CT. Future studies should design OA-specific EXGs and include patient subgroups to expand the impact of interventions using virtual systems. Full article

Background: The Xpert MTB/RIF Ultra assay (Ultra) is a second-generation molecular diagnostic test for tuberculosis (TB). The “Trace Call” result was added as a semi-quantitative category for extremely low bacillary loads. The prevalence and interpretation of Trace Call results remains insufficiently elucidated in the context of community-based active case finding (ACF). Methods: We organized 56 days of mobile chest X-ray (CXR) screening events in Ho Chi Minh City, Viet Nam, between October 2020 and March 2021. Participants were screened verbally and by CXR and tested by Ultra, if eligible. Persons with a Trace Call were re-tested on Ultra per national guidelines. qXRv3 computer-aided detection software was used for post hoc quality control of CXR interpretation. We calculated descriptive statistics and fitted mixed-effect multivariate regression models to identify factors associated with Trace Call results and confirmatory diagnosis. Results: A total of 16,698 people were screened by CXR to detect 185 Ultra-positive participants, including 142 persons with a confirmed TB diagnosis. Among Ultra-positive participants, 38.4% (71/185) had Trace Call results. Of these, 85.9% (61/71) were re-tested, and 45.9% (28/61) were bacteriologically-confirmed, comprising 19.7% (28/142) of the final number of confirmed diagnoses. Having a low qXR abnormality score (<0.5) (aOR = 4.97; 95%CI: [1.88, 13.14]; p = 0.001) and a history of TB within 5 recent years (aOR = 3.53; 95%CI: [1.69, 7.35]; p = 0.001) were associated with an initial Trace Call. Conclusions: The Trace Call can improve ACF detection, particularly in earlier stages of disease with limited pulmonary deterioration. However, participants with a history of TB had higher rates of Trace Call, reinforcing the need to interpret test results in this group with caution. Full article

With the impacts of climate change, floods have become increasingly frequent in recent years. Estimating flood hazard thresholds and peak floodwater levels based on flood frequency analysis is crucial for anticipating and preparing for potential flooding events. This study aims to estimate flood hazard thresholds, flood occurrence probabilities, and the return periods of peak floodwater levels in the Nokoue lake watershed in Benin. To achieve this, the standardized water level index, also known as the Flood hazard Index, was calculated to estimate flood hazard thresholds. The three best probability distribution models, Gumbel, Generalized Extreme Value (GEV), and Generalized Pareto (GPA), were selected to project future floodwater levels using annual maximum daily water level data for extreme floods from 1997 to 2022, obtained from a water gauge site at Nokoue lake. Three goodness-of-fit tests were applied to identify the best-fitting probability distribution model: a Taylor diagram (three-dimensional analysis), a cumulative probability density diagram based on the root-mean-square error (RMSE), and an L-moment diagram (two-dimensional analysis). The Flood hazard Index values ranged from −1.10 to +3.40, with 77.78% showing positive indices and 22.22% showing negative indices. The flood hazard thresholds were classified in ascending order of index values: limited hazards, moderate hazards, significant hazards, and critical hazards. The analysis results indicate that the flood hazard thresholds are defined as follows: below 3.94 m for limited hazards, from 3.94 m up to 4.04 m for moderate hazards, from 4.04 m to 4.14 m for significant hazards, and above 4.14 m for critical hazards. The distribution model analysis showed that the Gumbel distribution best fits the Nokoue lake watershed, with an RMSE of 0.0724, compared to 0.0754 and 0.0761 for the GEV and GPA models, respectively. The annual maximum daily water levels for various non-exhaustive return periods, 2, 3, 5, 10, 25, 50, and 100 years, were estimated and compared. The return period for the highest recorded annual maximum daily water levels (4.4 m/day) in the Nokoue lake watershed were calculated to be 12, 15, and 15 years using the Gumbel, GEV, and GPA models, respectively. Quantile analysis revealed that the Gumbel distribution produced overestimated results compared to the GEV and GPA models for return periods exceeding 10 years. Exceptional and very exceptional hydrological events have return periods of 100 and 150 years, corresponding to peak flow levels of 4.95 m and 5.05 m respectively. Finally, the results of this study will be invaluable for flood hazard managers in monitoring flood alerts and for water resource engineers in determining dimensions for designing flood control structures such as spillways, dams, and bridges, thereby improving the management of recurrent flooding events. Full article

Background/Objectives: The timely and accurate detection of atrial fibrillation (AF) is critical from a clinical perspective. Detecting short or transient AF events is challenging in 24–72 h Holter ECG recordings, especially when symptoms are infrequent. This study aims to explore the potential of deep transfer learning with ImageNet deep neural networks (DNNs) to improve the interpretation of short-term ECHOView images for the presence of AF. Methods: Thirty-second ECHOView images, composed of stacked heartbeat amplitudes, were rescaled to fit the input of 18 pretrained ImageNet DNNs with the top layers modified for binary classification (AF, non-AF). Transfer learning provided both retrained DNNs by training only the top layers (513–2048 trainable parameters) and fine-tuned DNNs by slowly training retrained DNNs (0.38–23.48 M parameters). Results: Transfer learning used 13,536 training and 6624 validation samples from the two leads in the IRIDIA-AF Holter ECG database, evenly split between AF and non-AF cases. The top-ranked DNNs evaluated on 11,400 test samples from independent records are the retrained EfficientNetV2B1 (96.3% accuracy with minimal inter-patient (1%) and inter-lead (0.3%) drops), and fine-tuned EfficientNetV2B1 and DenseNet-121, -169, -201 (97.2–97.6% accuracy with inter-patient (1.4–1.6%) and inter-lead (0.5–1.2%) drops). These models can process shorter ECG episodes with a tolerable accuracy drop of up to 0.6% for 20 s and 4–15% for 10 s. Case studies present the GradCAM heatmaps of retrained EfficientNetV2B1 overlaid on raw ECG and ECHOView images to illustrate model interpretability. Conclusions: In an extended deep transfer learning study, we validate that ImageNet DNNs applied to short-term ECHOView images through retraining and fine-tuning can significantly enhance automated AF diagnoses. GradCAM heatmaps provide meaningful model interpretability, highlighting ECG regions of interest aligned with cardiologist focus. Full article

This study investigated the effectiveness of nature-based solutions (NBSs) as a resilient strategy for mitigating urban flood risks in a developing hot arid country. The research method included the following steps: (a) performing a flood hazard risk assessment for the Fifth Settlement district in New Cairo, Egypt, (b) selecting best-fit NBSs, and (c) performance assessment. The process started with flood hazard analysis using hydrological data, topographical maps, urban planning, and land use maps, in addition to the history of storm events. This step defined the urban areas located in flood depth zones and categorized their flood hazard level. Exposure assessment considered the number and characteristics of population and buildings exposed to flood hazards. Vulnerability assessment determined the vulnerable characteristics of exposed populations and buildings to flood risk. The result of this assessment step indicated that there were 2000 buildings distributed in almost twenty neighborhood areas facing high flood risk. One of these urban areas with 72 building units, including residential, public, and services buildings, was selected to test the potential of integrating NBSs for flood-resilient land use planning and disaster preparedness. The selection of best-fit NBSs was based on a weighted-average sum matrix considering their climatic and contextual suitability and applicability. As a final step, numerical simulation models helped assess the efficiency of the selected NBSs for stormwater runoff reduction and the percentage of the volume capture goal. Five simulation models tested the efficiency of each NBS individually. Rain gardens achieved the highest stormwater capture percentage, while green roofs performed the least effectively, with capture rates of 43.6% and 9.9%, respectively. Two more simulation models were developed to evaluate the efficiency of NBSs when implemented in combination compared to the base case of using no NBSs. Permeable paving demonstrated the highest effectiveness in volume capture. The result indicated that applying combined measures of NBSs over 54.1% of the total site area was able to capture 8% more than the required volume capture goal. Consequently, this study underscores the necessity of adopting tailored solutions and integrated approaches using NBSs for flood risk mitigation. This necessitates testing their performance under site-specific conditions and future climate projections. Full article