Search Results (1,458)

Background/Objectives: Low back pain (LBP) is one of the most common musculoskeletal conditions globally and a leading cause of disability. University populations may be particularly vulnerable due to prolonged sitting, academic stress, and frequently suboptimal ergonomics, especially in rapidly expanding higher education systems such as those in Saudi Arabia. This systematic review and meta-analysis aimed to synthesize evidence on the prevalence of LBP among university attendants in Saudi Arabia and to quantify its associations with key demographic and environmental risk factors. Methods: We systematically reviewed observational studies reporting LBP prevalence and/or risk factors among university students and faculty in Saudi Arabia published in English, following Cochrane methodological guidance and PRISMA 2020 reporting recommendations. The protocol was prospectively registered in PROSPERO (CRD420250654048). We searched PubMed, Embase and CINAHL from inception to February 2025. Two reviewers independently screened studies, extracted data, and assessed risk of bias using the Joanna Briggs Institute checklist for analytical cross-sectional studies. Random effects meta-analyses were used to pool prevalence estimates across recall periods, regions, populations, and measurement tools, and to calculate pooled odds ratios (ORs) for age, sex, smoking, family history of LBP, and college seating conditions. Heterogeneity, subgroup, and sensitivity analyses were undertaken. Results: Thirteen cross-sectional studies were included. The overall pooled prevalence of LBP was 57% (95% confidence interval [CI] approximately 43–71), with substantial heterogeneity. Prevalence varied by recall period, region, population group, and measurement instrument; pooled prevalence was 58% among students and 50% among faculty. Increasing age (OR 1.17, 95% CI 1.01–1.34) and poor college seating conditions (OR 1.42, 95% CI 1.07–1.76) were significantly associated with LBP. Male gender, smoking, and family history showed non-significant pooled effects. These estimates are limited by substantial between-study heterogeneity, variable measurement tools, and exclusively cross-sectional designs, which restrict causal inference. Conclusions: LBP is prevalent among university attendants in Saudi Arabia, affecting both students and faculty. The consistent associations with age and seating ergonomics highlight the need for ergonomic classroom redesign and age-sensitive preventive strategies. Future work should adopt standardized LBP measures and longitudinal designs to clarify causal pathways and evaluate targeted interventions. Funding: This work was supported by the Deanship of Graduate Studies and Scientific Research at Jouf University (grant DGSSR-2026-NF-01-002). Full article

The construction sector contributes to global CO₂ emissions and resource consumption, highlighting the need for sustainable design strategies. In this context, building envelope performance plays a key role, supported by digital technologies. This study proposes an automated BIM-MCDM workflow to select the optimal wall stratigraphy with Aerogel, EPS, and Rock Wool thermal insulation layers. The evaluation indicators are organized into three thematic clusters: Thermal Performance (TPI), Environmental Sustainability (ESI), and Economic Indicators (EI). Insulation alternatives and indicators are modeled in Autodesk Revit, enabling parametric variation in insulation layers and generating multiple stratigraphic configurations. Performance indicators are automatically calculated through a BIM-VPL integration using Dynamo, Microsoft Excel, and Tally. Fully interoperable parametric scripts enable data extraction from the BIM model, regulatory compliance verification, and the transfer of results back to the BIM model. Finally, indicator values are weighted and evaluated using an MCDM analysis based on the AHP method, fully implemented in Dynamo. The results indicate that EPS ranks first due to its strong performance in TPI and ESI, followed by Aerogel, influenced by EI, and Rock Wool, which shows a lower contribution to ESI. This research contributes to data-driven decision-making and the digitalization of sustainability-oriented performance assessment for building envelopes. Full article

This article proposes a calibration method combining line chromatic confocal and 3D point cloud processing to solve surface damage and low efficiency in traditional roughness sample calibration. Line chromatic confocal sensors scan roughness samples to obtain dense point clouds. We propose a back projection mechanism, the adaptive density-based spatial clustering of applications with noise statistical outlier removal (BPM-ADBSCAN-SOR) algorithm that utilizes the ADBSCAN and SOR algorithms to address outlier noise and near-field noise in low-resolution point clouds, respectively, and then employs bounding boxes to crop the original high-resolution point cloud, thereby achieving multi-scale noise removal and point cloud clustering. We propose a Steady-State Confidence-Weighted Robust Gaussian Filtering (SSCW-RGF) algorithm, which calculates the range of the steady-state region, designs a steady-state region credibility weighting function to apply a weighted correction to the baseline fitting results, and then incorporates M-estimation theory to develop a robust Gaussian filtering algorithm weighted by steady-state region credibility, thereby mitigating the impact of outliers on Gaussian baseline fitting. Experiments verify the system accuracy: repeatability standard deviation is 0.0355 μm, relative repeatability error 0.3984%. Compared with reference block nominal values, the maximum absolute error is −0.745 μm, meeting specification tolerance. Compared with the contact profilometer, the maximum absolute error is 0.050 μm, the maximum relative error is +4.5%, and the calibration efficiency is improved by 90%. It provides a new approach for surface roughness calibration Full article

On 4 December 2025, nearly two years after the 2024 Mw 7.0 Wushi earthquake, an Mw 5.8 event struck the nearby county of Aheqi, southwestern Tianshan. Owing to the subparallel strikes of both nodal planes and the interspersed hypocenter locations among regional structures in the reported focal mechanisms, the exact fault geometry of this event remains unresolved, impeding a better understanding of regional tectonic activity and the associated seismic hazards. To resolve this, we applied Interferometric Synthetic Aperture Radar (InSAR) technique to map the coseismic deformation and invert for the fault geometry and slip pattern. Significant tropospheric delays are mitigated using a moving-window linear model and a multi-interferogram weighted averaging strategy. The result shows significant uplift (~5.0 cm for ascending track and ~6.0 cm for descending track), indicating thrust-dominated mechanism. Bayesian inversion reveals two possible fault models: a 31.6° north-dipping blind thrust or a 54.4° south-dipping back-thrust. While both fault planes fit the InSAR observations, integrated evidence from the absence of back-thrust development conditions, the surface deformation pattern, and regional topography indicates that the north-dipping Aheqi fault is the causative structure. Together with the steeper Maidan fault to the north, it forms the Orogen Basin boundary along the southern Tianshan piedmont. Our findings highlight that resolving moderate blind-thrust seismogenic structures using InSAR requires integration with pre-existing structural and geomorphic evidence. Furthermore, Coulomb stress calculations indicate a rupture-promoting effect from the Wushi earthquake, which occurred on a reactivated fault, onto the Aheqi event, with stress loading exceeding 2 bar at the hypocenter. Thus, the potential for stress-driven sequential rupture between reactivated and present-day active structures necessitates an updated seismic hazard assessment in the southern Tianshan. Full article

Windsurfing (WS) and kitesurfing (KS) share the same environment but differ in biomechanics and equipment demands. This cross-sectional study compared physical performance between WS and KS athletes. Twenty-five male recreational athletes participated (WS n = 13, age 27.7 ± 7.0 years; KS n = 12, age 29.0 ± 7.5 years). Body composition, isometric strength (handgrip and back-and-leg dynamometer), dynamic balance (Y-Balance Test: YBT), functional movement quality (FMS), and drop-jump performance (ground contact time, reactive strength index, jump height, take-off time) were assessed. Groups were compared using the Mann–Whitney U test (p < 0.05), and Cliff’s δ was calculated for significant outcomes. Participant characteristics were similar, although surfing experience was greater in WS. KS showed higher leg strength (p = 0.041; δ = 0.481) with no difference in handgrip strength. KS also demonstrated higher FMS shoulder mobility (p = 0.022; δ = 0.532) and total FMS score (p = 0.014; δ = 0.577). No between-group differences were found for YBT metrics or drop-jump variables (p > 0.05). These findings indicate that KS athletes exhibit greater isometric pulling strength and movement proficiency, whereas balance and reactive jump performance are comparable, supporting discipline-specific conditioning priorities. Full article

White-backed and Ash-grey cows yielded an average of 6212 kg and 6078 kg of milk per year, with 4.25–4.28% fat and 3.37–3.40% protein, while Holsteins averaged 10,694 kg with 4.47% fat and 3.45% protein. The study aimed to analyse the fatty acid (FA) profile of milk from two local cow breeds, compare them with that of Holstein cows, and evaluate the influence of lactation number, productivity indicators and milk colour. The study was carried out with White-backed (n = 40), Ash-grey (n = 49), and Holstein (n = 51) cows. Based on lactation number, cows were divided into two groups. Composite milk samples from all quarters of each cow were collected. Two additional milk samples were taken: 1st to assess milk colour and the second to determine the fatty acids profile. Productivity data of cows were provided from the Livestock Information System. Statistical analysis included calculating means and standard deviations or standard errors of the mean. One-way and two-way ANOVA (breed and lactation) were used, and Duncan’s test was applied to compare mean values between groups. White-backed cows contained greater proportions of C17:0, C17:1, C18:3 ω3, and C20:0 (p < 0.05), as well as higher total omega-3 and polyunsaturated fatty acid (PUFA) contents. Parity did not have a significant effect on productivity indicators, but parity influenced the FA profile. Milk from 1st-lactation Ash-grey cows showed higher levels of PUFA and omega-6 fatty acids (p < 0.05). Milk from Ash-grey cows has more favourable visual attributes, indicating improved suitability for dairy processing, where colour uniformity is important for technological quality. Full article

The operational reliability of Emergency Diesel Generators (EDGs) is paramount for the safety of nuclear power plants. This study investigates the fretting wear mechanism on the non-working back-face of connecting rod big-end bearings—a critical failure mode that can lead to catastrophic engine damage. A synergistic approach was employed, integrating theoretical pressure calculations, on-site strain measurement experiments, and high-fidelity non-linear finite element analysis (FEA). The results demonstrate that while the theoretical design back-face pressure ranges from 8.1 to 10.1 MPa, the actual pressure is highly sensitive to bolt preload. A 16.2% attenuation in preload (from 550 kN to 461 kN), common during maintenance cycles, causes the interfacial pressure to drop to 6.9 MPa, falling below the recommended safety threshold of 7 MPa required to inhibit fretting. Furthermore, comparative experiments reveal that used bearings exhibit significantly lower and less uniform radial pressure retention compared to new bearings, even when physical dimensions appear compliant. Dynamic FEA indicates that peak inertial loads induce an out-of-roundness (DOR) of 0.295 mm, triggering a transition from a “partial slip” to a “macro-slip” regime at the interface. The findings confirm that the coupling of preload attenuation and loss of bearing elasticity drives the fretting process, providing a theoretical basis for optimized maintenance and selective assembly strategies. Full article

Predicting the settlement behavior of jet-grout column groups in reclaimed coastal areas remains a significant geotechnical challenge, as conventional models do not capture the complex interaction between isolated stiff columns and the compliance of the composite system under wide-area loading. This study presents a field-calibrated analytical approach that reconciles single-column mechanics with full-scale group performance at a port terminal founded on highly compressible, liquefaction-prone marine backfill improved by 800 mm jet-grout columns. An extensive field-testing program—including cone penetration tests (CPTs), single-column load tests (SCLTs), and surface loading tests (SLTs)—was conducted. SCLT results revealed an elastic modulus exceeding 10 GPa, and CPT data confirmed up to a 250% increase in inter-column soil tip resistance. However, SLTs under an 85 kPa operational load yielded a back-calculated system stiffness of approximately 105 MPa, which is drastically lower than the theoretical unit cell prediction of 933 MPa. This empirical relation demonstrates that unit cell models fundamentally overestimate jet-grout group stiffness. Rather than proposing a site-specific static mobilization factor (β ≈ 0.11), this study introduces a novel, adaptive methodology. By systematically integrating single-column rigidity, group interaction, and stress transfer mechanics into untreated soil, this framework establishes a robust paradigm for accurately predicting composite stiffness and settlements across diverse geotechnical conditions. Full article

Purpose: The aim of this study was to develop a concept for adjustment planning of intraocular lens orientation axes after cataract surgery with implantation of toric intraocular lenses (tIOLs) and to predict the spectacle refraction after tIOL re-alignment. Methods: This calculation concept based on paraxial spherocylindrical vergence transformations uses the actual spherocylindrical refraction at the spectacle plane, corneal power, and the labelled power and measured axis of the implanted tIOL to minimise the refractive cylinder by simulating the rotation of the tIOL in the eye. The axial lens position is derived from simple prediction models using anterior chamber depth and lens thickness or axial length from preoperative biometry or the equivalent tIOL power. The new target axis is predicted together with the spherocylindrical refraction after re-alignment of the tIOL. Results: To show the applicability of this calculation model, we provide four clinical working examples: example 1 deals with keratometric power values; example 2 deals with keratometric curvature values, including surgically induced astigmatism and a statistical posterior astigmatism correction for the cornea (both examples with a thin cornea model); example 3 deals with corneal curvature data for the front and back surface; and example 4 deals with keratometric power data and corneal back surface power data, including surgically induced astigmatism (both examples with a thick cornea model). Conclusions: The effect of tIOL axis adjustment after cataract surgery can be predicted based on actual refraction, corneal power, tIOL power and the measured axis, and a simulation of the tIOL axis rotation enables the best orientation with the lowest refractive cylinder at the spectacle plane to be found. Full article

Vegetable sweet potato shoot tips are harvested repeatedly for fresh markets, but harvest timing and cut length are still determined largely by experience, limiting their translation into mechanized design parameters and control thresholds. We conducted a two-factor shear-mechanics experiment using three cultivars (‘Fu 23’, ‘Fu 18’, and ‘HD-V4’) and five shoot-tip length levels (10–30 cm), while also measuring stem diameter and moisture content. Because shear tests were performed on short stem segments sampled from a fixed internodal position relative to the apex, the length factor is interpreted mainly as a field-operable harvest criterion and only secondarily as a variable partly associated with tissue position. Moisture content was uniformly high and did not differ among cultivars (p > 0.05). In a pooled two-way ANOVA, length significantly affected maximum shear force (p < 0.01), cultivar was also significant (p < 0.05), and the interaction was not significant (p > 0.05). After including stem diameter as a covariate, both diameter and length remained significant, whereas cultivar became non-significant, indicating that stem diameter explains much of the apparent cultivar difference in absolute load. The reported stress is nominal shear stress. Laboratory-based 95th percentile design loads with γ = 1.3 provide conservative engineering thresholds for preliminary design and harvest-window back-calculation. Full article

This article details a matrix-based mathematical method to calculate power flows and transmission losses in an electric grid specifically attributable to low-carbon and renewable energy sources (LCRES) (wind, solar, nuclear). The goal is to improve the transparency and reliability of Guarantees of Origin (GO) certificates. Current GO schemes rely on contractual accounting and neglect physical power losses, undermining consumers’ confidence that they receive “clean” energy. The method uses steady-state power flow analysis to derive a power-loss distribution coefficient matrix. This matrix accurately allocates grid losses back to the LCRES generating nodes, complying strictly with electrical engineering principles. It accommodates both time-varying renewable output and stable nuclear generation. The results offer highly accurate loss-attribution data, supporting more verifiable GOs, ensuring fair compensation for losses, and enhancing energy balance accuracy in hybrid power systems. Full article

The impact of large boulders transported by debris flows is a primary cause of structural damage to mitigation works. However, quantitative modeling remains difficult because of the scarcity of field measurements and the complexity of the flow medium. In this study, a theoretical model for boulder impact force in debris flows is developed using dimensional analysis based on the Buckingham theorem, subsequently simplified to two dimensionless parameters, and then validated through a series of controlled laboratory experiments. Marble spheres were used as impactors and were released to strike a rigid steel plate under three types of media: clear water, bentonite slurry, and debris flows containing particles of different size classes. The experiments were designed to isolate and quantify the influence of the flow rheology and the suspended solid phase on impact forces. The results show that the impact coefficient c is strongly governed by the debris flow yield stress, bulk density, and the size of suspended particles, following the relationship c = 0.183[τ/(rgd₁)]^−0.1(d/d₀)^0.05. Based on this relationship, a generalized formula for calculating boulder impact forces in debris flows is proposed. The model is further evaluated using field monitoring data from Jiangjiagou, Yunnan Province. The back-calculated boulder diameters fall predominantly within the range of 0.1–0.3 m (76.3–86.8%), which is consistent with field observations. These results indicate that the proposed model captures the essential physical mechanisms governing boulder impacts and provides a rational basis for selecting design parameters in debris flow mitigation engineering. The array-type piezoelectric impact sensing system designed in this study achieves high-precision and high-stability measurement of the impact force of large boulders in debris flows, providing a new sensing technology for debris flow impact monitoring. Full article

Background/Objectives: Morning erections provide an intercourse-independent indicator of nocturnal erectile physiology. We aimed to examine whether body mass index (BMI) and muscle strength are associated with morning-erection frequency in apparently healthy Japanese male university students. Methods: This cross-sectional study analyzed 125 men with complete data (170 assessed; 45 excluded). Handgrip and back muscle strength were measured using dynamometry; BMI was calculated from height and weight. Morning-erection frequency was assessed using a single 6-category item and was dichotomized as low vs. high. Univariable and multivariable logistic regression models were fitted. Exploratory principal component analysis (PCA) and k-means clustering (k = 2, silhouette-supported) were performed. Results: Seventy-four participants (59.2%) were classified as low frequency. Back muscle strength was associated with high frequency (univariable odds ratio [OR] 1.61; 95% confidence interval [CI] 1.07–2.42; and p = 0.021) and remained significant after adjustment for BMI and handgrip strength (OR 1.88; 95% CI 1.02–3.47; and p = 0.045), whereas BMI and handgrip strength were not significant. Clustering identified two clusters (n = 41 and n = 84); Cluster 2 (higher BMI/strength) had a higher proportion of high morning-erection frequency (48% vs. 27%). Conclusions: In apparently healthy young men, greater back muscle strength was independently associated with higher self-reported morning-erection frequency. In this cohort, 59.2% reported infrequent morning erections, suggesting potential relevance even in early adulthood. Given the exploratory clustering, the single-item outcome, and likely residual confounding, these findings are hypothesis-generating and warrant longitudinal validation. Full article

Background/Objective: To investigate short-term multidimensional recovery trajectories after physiotherapy with or without adjunctive pain education in individuals with Chronic low back pain (CLBP). Methods: This was a secondary analysis of a randomized controlled trial (RCT) of 92 participants (46 participants per group) comparing physiotherapy alone with physiotherapy plus pain education. Changes from baseline values over six weeks were calculated for pain intensity, disability, psychological well-being, and self-efficacy to define short-term recovery trajectories across domains, and were standardized prior to analysis. Descriptive characterization of recovery dimensions by principal component analysis and identification of different recovery trajectory clusters by k-means clustering were performed. Sensitivity analyses with multinomial logistic regression were performed to determine robustness after adjustment for baseline characteristics. Results: Three recovery trajectories were found: minimal recovery (n = 40), psychosocial-dominant recovery (n = 26), and global recovery (n = 26). In the physiotherapy-only group, participants were classified as minimal recovery (61%) or psychosocial-dominant recovery (39%), with no cases of global recovery. In contradistinction, 57% of participants receiving physiotherapy with pain education were classified as within the global recovery trajectory, with fewer classified as minimal recovery (26%) or psychosocial-dominant recovery (17%). Psychosocial-dominant recovery occurred in both groups, and was characterized by large improvements in psychological well-being and self-efficacy with more modest changes in pain and disability. The distribution of recovery trajectories between treatment groups was large (χ²(2)= 36.25, p < 0.001; Cramer’s V = 0.63). Conclusions: Distinct short-term recovery trajectories were found after physiotherapy with or without pain education in individuals with CLBP, reflecting heterogeneity in multidimensional recovery that is not reflected in mean-based outcome analyses. Full article

Background/Objectives: Sacroiliac joint (SIJ) dysfunction is a common yet frequently underdiagnosed cause of chronic low back pain. This study aimed to compare the clinical effectiveness of ultrasound-guided corticosteroid and ozone injections in patients with chronic low back pain due to SIJ dysfunction. Methods: This comparative clinical study included 64 patients with chronic sacroiliac joint (SIJ) dysfunction who received ultrasound-guided SIJ injections with either corticosteroid (n = 31) or ozone (n = 33). Participants had a mean age of 45.0 ± 7.7 years, and the sex distribution was 42/22 (female/male). Pain intensity was assessed using the Numeric Rating Scale (NRS), disability using the Oswestry Disability Index (ODI), and quality of life using the Short Form-12 Physical (PCS) and Mental (MCS) Component Summary scores. Outcomes were evaluated at baseline, 3 months, and 6 months. Longitudinal changes were analyzed using two-way repeated-measures ANOVA (group × time) with Bonferroni-adjusted post hoc comparisons. Effect sizes were calculated using Cohen’s d. Normality and homoscedasticity were assessed (Shapiro–Wilk and Levene tests), and baseline comparisons were performed using appropriate parametric or non-parametric tests. Results: Both treatments significantly improved pain, disability, and quality of life at 3 months (p < 0.01). However, improvements were significantly greater and more durable in the ozone group across all outcomes at both 3 and 6 months (p < 0.01). At 6 months, between-group differences favored ozone for NRS (mean difference −2.81; Cohen’s d = −2.36), ODI (−6.05; d = −1.46), SF-12 PCS (+4.24; d = 1.24), and SF-12 MCS (+4.22; d = 0.83). A ≥50% pain reduction was achieved at 3 months in 97.0% of ozone-treated patients versus 45.2% of corticosteroid-treated patients (p < 0.01) and persisted at 6 months in 18.2% and 0% of patients, respectively (p < 0.05). The magnitude of improvement in the ozone group exceeded commonly reported Minimal Clinically Important Difference (MCID) thresholds for chronic low back pain outcomes, supporting clinical relevance. Conclusions: Ultrasound-guided ozone injection provided greater and more durable improvements in pain relief, functional status, and quality of life compared with corticosteroid injection in patients with SIJ dysfunction. Full article