High Magnitude Research Articles

Dark continuous noise from visual pigment as a major mechanism underlying rod–cone difference in light sensitivity

Retinal rods and cones underlie scotopic and photopic vision, respectively. Their pigments exhibit spontaneous isomerizations (quantal noise) in darkness due to intrinsic thermal energy. This quantal noise, albeit exceedingly low in rods, dictates the light threshold for scotopic vision. The same quantal noise in cones, however, is too low to explain the much higher diurnal light threshold. Separately, a dark continuous noise is present in rods, long accepted to originate from an intrinsic random activation of the cyclic guanosine monophosphate (cGMP)-phosphodiesterase enzyme mediating phototransduction downstream of the pigment. Here, we report the surprising finding that most of this rod dark continuous noise actually originates from rhodopsin itself. Importantly, we found the same continuous noise with a much higher magnitude from cone pigments. The rod and cone continuous noises are apparently both associated with a hitherto unrecognized "metastable" pigment conformational state physiologically resembling that in apo-opsin (opsin devoid of chromophore) and is intermittently active for very brief moments. The cone holopigment's high continuous noise is expected to act as an intrinsic equivalent light and adapt the cone dramatically, accounting for a major part of the light-sensitivity difference between rods and cones in darkness.

Understanding the stress field at the lateral termination of a thrust fold using generic geomechanical models and clustering methods

Abstract. This study employs numerical simulations based on the limit analysis (LA) method to calculate the stress distribution in a model that includes a basal detachment, featuring the lateral termination of a generic fault under compression. We conduct 2500 2D and 500 3D simulations with varying basement and fault friction angles to analyze and classify the results into clusters representing similar failure patterns to understand the stress fields. Automatic fault detection methods are employed to identify the number and positions of fault lines in 2D and fault surfaces in 3D. Clustering approaches are utilized to group the models based on the detected failure patterns. For the 2D models, the analysis reveals three primary clusters and five transitional ones, qualitatively consistent with the critical Coulomb wedge theory and the influence of inherited structural and geometric aspects over rupture localization. In the 3D models, four different clusters portray the lateral prolongation of the inherited fault. High stress magnitudes are detected between the compressive boundary and the activated or created faults and at the root of the inherited active fault. Tension zones appear near the outcropping surface relief, while stress decreases with depth at the footwall of the created back thrusts. A statistical cluster-based stress field analysis indicates that for a given cluster, the stress field mainly conserves the same orientations, while the magnitude varies with changes in friction angles and compressive field intensity, except in failure zones where variations are sparse. Small parametric variations could lead to significantly different stress fields, while larger deviations might result in similar configurations. The comparison between 2D and 3D models shows the importance of lateral stresses and their influence on rupture patterns, distinguishing between 3D analysis and 2D cross-sections. Lastly, despite using small-scale models, stress field variations over a span of a couple of kilometers are quite large.

Risk-Averse, Integrated Contract, and Open Market Procurement with Quantity Adjustment Costs

This paper examines the issue cost-effective procurement of a commodity product when its spot (open) market prices are stochastic, contract prices are previously determined, and there are costs associated with adjusting (i.e., switching) the procurement quantities from an alternative. Spot (open) market and contract as sole modes of procurement could present risks of high magnitude and uncertainty of expenses for the buyer. To address these risks, a risk-averse buyer may consider simultaneous use of both alternatives with adjustment of the purchase quantities from both the alternatives over time. Scenarios when the switching costs depend on the relative prices of the two alternatives are considered. The problem being analytically intractable, a mixed method decision model combining analytical and computational techniques to analyze the problem is proposed. The model helps identify expected optimal contract and spot market procurement quantities with respect to unknown spot prices and known contract prices over the planned procurement horizon when procurement quantity adjustment costs are influenced by the spends. The analysis reveals that it is cost-effective to continue purchasing with an existing pattern of procurement from the two alternatives until the contract to spot market price ratio reaches a threshold level and then to change the proportion of quantity purchased from the two alternatives. Using numerical analysis, we illustrate the theoretical and managerial significance of this stickiness to continue with an existing pattern until an adjustment.

Phacovitrectomy vs. consecutive vitrectomy for idiopathic macular holes: short and long-term outcomes and OCT image quality assessment

PurposeTo compare short- and long-term anatomical, functional, and refractive outcomes between combined phacovitrectomy (PVS) and consecutive vitrectomy (CVS) for idiopathic macular holes (MHs). Also, to evaluate the role of preoperative optical coherence tomography (OCT) image quality in guiding surgical selection.MethodsThis retrospective study analyzed 183 phakic MH eyes operated between 2012 and 23, with patients divided into PVS and CVS groups. Demographic and ocular data, MH features, visual acuity (VA), refraction changes and postoperative outcomes, and follow-up details were collected. Pre- and post-operative OCT scans were evaluated for MH characteristics, OCT image quality, and surgical outcomes at short-term (≤ 3 months) and long-term (≥ 5 years) intervals.ResultsThe study included 144 eyes in PVS group and 39 in CVS group. Median follow-up duration was 16 months for PVS group and 72 months for CVS group (p < 0.001). Both groups showed significant VA improvements and comparable MH closure rates at short-term follow-up. However, CVS group had significantly better postoperative VA at short-term (p = 0.001) and long-term (p = 0.017) intervals. The preoperative OCT quality index did not significantly differ between groups and was ineffective in assessing cataract grade or guiding surgical decisions. Both groups experienced a myopic refractive shift, with a higher magnitude in the PVS group (p = 0.04). Postoperative complications were similar between the groups.ConclusionCVS achieves better long-term VA than PVS following MH repair, despite similar anatomical outcomes. Preoperative OCT quality index is not effective for guiding surgical decisions, and careful refractive planning is essential, especially for PVS patients, to address postoperative myopic shifts.Clinical trial registration numberNot applicable.

Home delivery and associated factors among women who gave birth after antenatal care follow-up in the last 6 months in Jabitehnan District, Northwest Ethiopia: mixed community-based study

IntroductionMaternal mortality is a global issue, with developing countries accounting for over 99% of maternal deaths, with 30% of Ethiopian mothers dying from pregnancy-related causes. This study aimed to assess the magnitude, associated factors, and reasons for home delivery among women who gave birth after antenatal care follow-up in the last 6 months in Jabitehnan District, Northwest Ethiopia.MethodsA mixed community-based study was conducted on women who gave birth after antenatal care follow-up in the last 6 months. Data was collected through face-to-face interviews and structured questionnaires. Bivariate and multivariable logistic regressions were performed to identify factors associated with home delivery. Qualitative data were collected through focus group discussions and in-depth interviews and analyzed using a thematic content analysis method.ResultIn this study, the magnitude of home delivery after ANC follow-up among mothers who gave birth in the last 6 months was 37%, with a 95% CI of 32.5 and 41.5. Pregnancy plan [AOR: 4.56 (2.65, 7.86)], experience of abortion AOR: 3.01 [1.631, (5.55)], ANC follow-up at public hospitals [AOR: 1.89 (1.119, 3.18)], and pregnant mothers visited at home by healthcare providers during their ANC follow-up absent [AOR: 1.61 (1.02, 2.53)] were predictors of home delivery. Poor counseling during ANC, and lack of pregnancy plans, traditions, and beliefs were reasons for home delivery.ConclusionThe study reveals a high magnitude of home delivery as compared to a study done in Bahir Dar (21.2%). Factors include pregnancy plans, health institution type, abortion experience, and absence from antenatal care. Poor counseling during ANC, and lack of pregnancy plans, traditions, and beliefs were reasons for home delivery. Health professionals should receive training in communication and counseling techniques, and they should encourage mothers to plan their pregnancies and visit facility delivery services during ANC follow-up.

Karst geomorphology analysis for geohazard assessment via seismic relief and dip attributes in Jx carbonate field, Central Luconia Province, Malaysia

Carbonate reservoirs in the Central Luconia Province of Malaysia underwent significant karstification during the Miocene. Such features have a detrimental impact on drilling operations, as has been reported for over 40 years in this province. This implies that the karst architecture and geometry may exhibit potentially high-risk behaviours during drilling activities, necessitating a thorough investigation of the features. This study aims to achieve several objectives using Jx field subsurface data, i.e., 3D seismic data and well data, including (1) analysing the interrelationship between karsts and faults, (2) examining the appropriate and effective attributes for analysing the geomorphology of the karst surfaces, and (3) conducting comparative and analog studies to gain a comprehensive understanding of karst formation and characteristics. This research attempted to determine the dimensions and extent of the faults and karsts, which were discovered to be highly connected, and this endeavor is critical for assessing the potential hazardous risk features within the platform. The major fault lineaments that bound the study field were interpreted using the Automatic Fault Extraction (AFE) module application combined with the manual fault-picking technique in the PaleoScan 2022 software. Four main horizon surfaces within the carbonate interval were selected for evaluating karst geomorphology using appropriate seismic attributes, as geomorphology is an important subject that requires serious attention, particularly when determining low-risk regions for drilling programs. Two attributes were extracted from the horizon surfaces: seismic relief and dip attributes, which efficiently distinguish the karst features and define the structural morphology of karsts. Dendritic karst networks, as well as karst collapses or sinkholes, are the most common karst features observed. These features exhibit discontinuity form and synclinal expression (high dip magnitude) when viewed in seismic and using the applied attributes. The comparative and analog study was conducted in Niah Caves, Miri, Sarawak, Malaysia, using karst interpretation employing digital elevation model (DEM) maps and fieldwork. Most of the delineated karst features observed on the DEM map of the Niah Caves are similar to those discovered in the Jx field; however, their dimensions vary between the two carbonate buildups.

Assessment of active tectonics based on GIS and statistical model: A case study of upper Alaknanda catchment (western Himalaya, India)

Due to continuing deformation of the Earth’s crust, degradation and aggradation processes, the upper part of the Alaknanda basin lying in the Garhwal Himalaya, India, is considered to be tectonically active. Active tectonics in this region made a considerable impact on the drainage system and the topographic expression. Using a digital elevation model (DEM) with a resolution of 30 m * 30 m and based on eight geomorphic indices [hypsometric integral (HI), drainage texture (Dt), asymmetry factor (AF), ruggedness number (Rd), circularity ratio (Rc), valley floor width/height ratio (Vfw), lemniscate coefficient (k) and basin shape index (Bs)], we evaluated active tectonics. Application of Index of Active Tectonic (IAT) and clustering model disclose the sub-watersheds in the southern part covering watersheds 16, 17 and near Badrinath sub-watershed 4, 9 and 8 are tectonically highly active (Class-1, 1.500-1.781). Cluster analysis defines two prominent clusters of sub-watersheds: 2, 4,14 and 15 in cluster 1; and 6, 7, 8 and 18 in cluster 2. Cluster 1 includes sub-watersheds 2, 4, 14, 15, and 16 and very high, high, and moderate IAT magnitudes. Sub-watersheds 6, 7, 8, and 18 are included in Cluster 2, which has very high and high tectonic activity

Nonionic Demulsifier for Smart Demulsification of Crude Oil Emulsion at Room and Moderate Temperatures.

This study reports the demulsification activity of a newly developed nonionic demulsifier (NID) via the condensation of glycolic acid ethoxylate lauryl ether with amine. The demulsification performance of the developed NID was assessed under room and moderate temperatures (25 and 60 °C), while the concentrations of NID were varied from 100 to 700 ppm at both temperatures in order to observe their oil-water separation efficiency. The demulsification mechanism was expatiated by determining the viscosity and elastic modulus of emulsion in the presence and absence of the NID. Adsorption at the oil and water interface was analyzed through a series of interfacial tension measurements. Accordingly, under the aforementioned temperatures, the optimal demulsification efficiency of the NID was 95% (25 °C) and 99% (60 °C) at 500 ppm. Viscosity determination at both temperatures revealed a drastic reduction in emulsion viscosity in the presence of NID, and the viscosity drop was of high magnitude at moderate temperatures (60 °C). Likewise, the elastic modulus measurements in bulk rheology revealed that the presence of NID in the emulsion weakened the elastic strength. Again, the interfacial modulus test exhibited the percolation of NID at the oil-water interface and the displacement of asphaltenes. Interfacial tension (IFT) measurements of the oil-water system at different NID concentrations showed that the particles were adsorbed at the oil-water interface. The IFT values of the oil-water system in the presence of NID ranged from 1.84 to 3.02 mN/m as compared to that of the NID-free oil-water system recorded as 16.11 mN/m. It is envisaged that this new nonionic demulsifier would be very useful in oilfields and petrochemical industries.

NaCl salt stress and PEG water stress differentially affect germination and early seedling growth of two sesame (Sesamum indicum L.) cultivars

Drought stress and salt stress are serious challenges to crop productivity in the arid lands. This work investigates the impact of NaCl-salt stress and PEG-water stress on germination and embryo growth of two sesame (Sesamum indicum L.) cultivars: Sohag 1 (Sohg) and Shandaweel 3 (Shnd). Seed dimensions, volume and weight were measured. The red Sohg seeds were larger with oblong appearance and lower density relative to the white Shnd seeds. Seeds were germinated in isosmotic solutions of NaCl and PEG-6000 at 0, − 0.103, − 0.205, − 0.410 and − 0.615 MPa. The time-based parameters (velocity, uniformity and synchrony of germination) were more reliable measures of germination efficiency than the final germination percentage. The impact of PEG was more severe than that of NaCl particularly on Sohg. The peak of daily germination was lowered and delayed under stress. The genotypic variability in germinability became evident under stress in favor of Shnd. Radicle length–a reliable measure of seedling growth–was subjected to stronger impact of NaCl than PEG. Although Na+ mobilization from seeds to embryos was indifferent in the two cultivars in PEG solutions, Shnd seedlings exhibited higher Na+ uptake from NaCl solutions. Whereas K+ mobilization was restricted by NaCl only in Sohg, it was hastened by PEG equally in the two cultivars. The stress-vulnerable Sohg recovered from stress with higher magnitude than did Shnd, particularly from the more stressing osmoticum (PEG). The indices of germination recovery were highest in PEG-pretreated Sohg while the biomass of recovered seedlings was highest in NaCl-pretreated Sohg.

Spatiotemporal Pattern Detection of Ground Deformations Induced by Extreme Rainfall using InSAR EGMS: The case of Cortina d’Ampezzo after Vaia Storm

Abstract. During October 2018 Vaia Storm occurred in the north of Italy, resulting in a huge amount of rainfall that was recorded. The focus here is given to Cortina d’Ampezzo area in the Veneto Region, due to the high importance of the area from touristic and sport perspectives and the presence of landslides. This study is devoted to investigating the impact of the severe sudden rainfall caused by this extreme atmospheric disturbance on the trends of ground deformations over this area, adopting a risk assessment perspective. The ground deformation Time Series (TS) have been derived from the European Ground Motion Service (EGMS) Ortho products derived from Sentinel-1 InSAR data. Then, according to the daily precipitation records and considering the time of this event as a turning temporal point, the TSs of all data points have been divided into pre-event and post-event phases. After obtaining the displacement rates in each phase, the quantified magnitude of changes in the pre-post rates has been calculated through a proposed simple formulation. The spatial distribution of the deformation parameters (i.e., pre-event displacement velocity and change in the pre-post displacement velocities) is found to be a practical tool for gaining comprehensive knowledge regarding the ground deformation and the effect of the extreme weather conditions on the displacement trends over the area. Furthermore, the positioning of the occurrence of deformation parameters has been compared to the landslide inventory of the area. The results showed that the extreme rainfall caused severe acceleration of displacements, more significant in horizontal East-West direction rather than vertical Up-Down direction. Some slight deceleration has been also detected. No initiation (or reactivation) of the stable zones was witnessed, and the portions with high magnitude of pre-event velocities are the ones whose displacement rates have been remarkably modified due to the severe event.

Identification of ocular artifact in EEG signals using VMD and Hurst exponent.

Electroencephalographic (EEG) readings are usually infected with unavoidable artifacts, especially physiological ones. One such physiological artifact is the ocular artifacts (OAs) that are generally related to eyes and are characterized by high magnitude and a specific spike pattern in the prefrontal region of the brain. During the long-duration EEG acquisition, the retrieval of important information becomes quite complicated in prefrontal regions as ocular artifacts dominate the EEG recorded, making it difficult to discern underlying brain activity. With the progress and development in signal processing techniques, artifact handling has become a progressive field of investigation. This paper presents a framework for the detection and correction of ocular artifacts. This study emphasizes improving the quality and reducing the time complexity by using higher-order statistics (HOS) for artifact identification and variational mode decomposition (VMD) for OA correction. An overall SNR of 14 dB, MAE of 0.09, and PSNR of 33.59 dB has been attained by the proposed framework. It was observed that the proposed HOS-VMD surpassed the state-of-the-art mode decomposition techniques.

Tectonic activation and the risk of Ilisu Dam collapse to Iraq through modelling and simulation using HEC-RAS

Floods caused by dam failures can cause huge losses of life and property, especially in estuarine areas and valleys. In spite of all the capabilities and great improvements reached by man in the construction of dams and their structures, they will remain helpless before the powerful forces of nature, especially those related to tectonic activation, and the occurrence of earthquakes of different intensities.The region extending from the Ilisu Dam in Turkey to the Mosul Dam in Iraq was chosen as an area for this study, and the HEC-RAS application was used to simulate the collapse of the Ilisu Dam due to a major earthquake, to know the magnitude of the risks and losses that could result from this. The Ilisu Dam was built very close to a highly tectonically active fault system, particularly the East Anatolian Fault (EAF), which is one of the largest tectonically active faults in the world with a length of 500 km. This region has witnessed past and present earthquakes of high magnitude (M > 7), especially in the EAF, so the construction of the Ilisu Dam near the EAF fault system is of great concern, as it was built in a basin with very complex seismic activity and geology.Using the HEC-RAS simulation application, the study found that the flood resulting from the collapse of the Ilisu Dam would reach the edges of the Mosul Dam Lake in just 13 h. With a flow of more than 100,000 m3/s, more than 10 billion m3 of water will flow into the Mosul Dam Lake within four days of the disaster. This will lead to the collapse of the Mosul Dam and direct the flood wave of the collapse of these dams towards Baghdad through Mosul, Tikrit, and Samarra. This could pose risks to all Iraqi cities located within the Iraqi sedimentary plain (Mesopotamia), from south of the Mosul Dam up to Basra, in a scenario similar to Noah’s Flood.

Maximum heart rate prediction equations based on field-tests with adequate clinical applicability for aerobic exercise prescription to individuals after stroke

Objectives 1) to develop two maximum heart rate (HRmax) prediction equations for individuals after stroke; 2) to investigate its validity. Methods The HRmax was obtained by a Cardiopulmonary Exercise Test (CPET). Participants also completed the Six-minute Walking Test (6MWT) and the Incremental Shuttle Walking Test (ISWT). Results 60 individuals (54(12) years; 64(69) months after stroke) were included. Twenty individuals (58(10) years; 67(61) months after stroke) were included in the cross-validation group. For the first model, the following equation was generated (equation-1): HRmax= 87.655 + 0.726 (HRpeak in the 6MWT) − 0.386 (age in years), (R2=0.53; Standard Error of the Estimate (SEE)= 15.35; p < 0.0001). For the second model, the following equation was generated (equation-2): HRmax= 96.523 + 0.681 (HRpeak in the ISWT) − 0.039 (walking distance in meters in the ISWT) − 0.400 (age in years), (R2=0.53; SEE = 15.51; p < 0.0001). Significant and high magnitude agreement was found between the HRmax obtained by the CPET and the predicted HRmax by equation-1 (ICC= 0.85; 95% CI= 0.63 − 0.94) and equation-2 (ICC= 0.72; 95% CI= 0.29 − 0.89). Conclusions Two HRmax prediction equations have been developed and showed adequate validity. Professionals will have the option of choosing one of the two equations to use.

Constitutive description of snow at finite strains by the modified cam‐clay model and an implicit gradient damage formulation

AbstractSnow, characterized as a unique granular and low‐density material, exhibits intricate behavior influenced by the proximity to its melting point and its three‐phase composition. This composition entails a structured ice skeleton surrounded by voids filled with air and spread with liquid water. Mechanically, snow experiences dynamic transformations, including bonding/degradation between its grains, significant inelastic deformations, and a distinct rate sensitivity. Given snow's varied structures and mechanical strengths in natural settings, a comprehensive constitutive model is necessary. Our study introduces a pioneering formulation grounded on the modified Cam‐Clay model, extended to finite strains. This formulation is further enriched by an implicit gradient damage modeling, creating a synergistic blend that offers a detailed representation of snow behavior. The versatility of the framework is emphasized through the careful calibration of damage parameters. Such calibration allows the model to adeptly capture the effects of diverse strain rates, particularly at high magnitudes, highlighting its adaptability in replicating snow's unique mechanical responses across various conditions. Upon calibration against established experimental benchmarks, the model demonstrates a suitable alignment with observed behavior, underscoring its potential as a comprehensive tool for understanding and modeling snow behavior with precision and depth.

Phonon-charge carrier dynamics via grain-boundary phase in equilibrium reaction of higher manganese silicide/CNF hybrid composites

Higher manganese (TE) silicide (HMS), an eco-friendly, low-cost, and earth-abundant p-type thermoelectric material, exposes a Nowotny chimney-ladder crystal structure, obeying the 14th-electron rule. Here, a hybrid composite of a carbon nanofiber (CNF) and HMS was synthesized by vacuum melting followed by spark plasma sintering, and its thermoelectric performance were demonstrated. The incorporation of CNF with HMS notably enhances the Seebeck coefficient and decline the thermal conductivity without significantly affecting the carrier concentration and electrical conductivity due to the interfacial energy filtering effect. A maximum Seebeck coefficient of 307 μV/K was recorded for the 0.5% CNF composite with HMS, leading to accomplish a high-power factor of 1755.63 μW/mK2 at 803 K. Also, interfaces, grain boundaries, and dislocations leading to the high magnitude of strain, confirmed from HR-TEM and strain analysis, leads to decrease in lattice thermal conductivity to 1.95 W/mK. As a result, HMS attains the peak zT value of 0.64, suggesting that carbon-based composites are a promising way to boost the thermoelectric performance of HMS-based compounds.

Effect of acupuncture on the sleep quality of hemodialysis patients in a capital city in the Northeast of Brazil

Objective: Analyze the effect of auricular acupuncture on the sleep quality of hemodialytic patients with chronic pain in a capital city in the Northeast of Brazil. Methods: This study includes double-blind, randomized in blocks and allocated at a rate of 1:1, controlled trial that was conducted in two hemodialysis clinics, with 94 chronic renal patients with chronic pain (auricular acupuncture [AA]: 47, sham acupuncture [SA]: 47). Both received 12 sessions for three months. We collected data using the Pittsburg Sleep Quality Index (PSQI). Data were analyzed using t-tests, Wilcoxon test and ANOVA. Results: Comparing the SA and AA groups, there was a statistically significant difference at baseline (p &lt; 0.001), a significant intergroup difference, and the AA group had better sleep quality than the SA group during and at the end of the 12 sessions (&lt; 0.001). A high magnitude of the effect of auricular acupuncture on sleep quality was found at the end of the sessions (D= -1.94). Conclusion: The auricular acupuncture intervention proved to be effective in improving the subjective sleep classification of renal patients.

Seismic capacity evaluation of a reinforced concrete frame infilled with precast modular block wall for enhancing the horizontal load

In this study, we propose a new concept for seismic retrofitting using precast modular block walls (PMBWs) to improve and complement the shortcomings of conventional retrofitting methods for reinforced concrete (RC) frames infilled with shear walls, masonry walls, and precast panels. The PMBW retrofitting method maximizes the advantages of factory-produced modular blocks, innovatively enhancing the constructability and integrity of connections between the existing frame and the infilled PMBW. Additionally, the PMBW reinforcement method improves seismic resistance without significantly increasing structural weight, and the required amount of reinforcement can easily be calculated because the strengthening technique involves typical frame infilling. For RC buildings with non-seismic details dominated by shear failure, the application of this seismic reinforcement method readily ensures sufficient strength. A pseudo-dynamic test was conducted on a full-scale two-story frame, based on an existing RC building with non-seismic details, to evaluate the restoring force characteristics, strength enhancement effects, reinforcement strain, and seismic response control capabilities of the PMBW reinforcement system. Based on the pseudo-dynamic test results, the restoring force characteristics for nonlinear dynamic analysis of the PMBW-reinforced specimen were identified. Finally, nonlinear dynamic analysis was conducted using the proposed restoring force characteristics, and the results were compared with the pseudo-dynamic test results. The unreinforced RC frame experienced shear failure at a design basis earthquake magnitude of 200 cm/s2. However, the frame reinforced with the PMBW sustained only minor damage. Even at higher magnitudes under maximum considered earthquake conditions of 300 cm/s2 and large-scale earthquake conditions of 400 cm/s2, only a slight amount of damage was projected from the analysis. Thus, the newly developed PMBW frame infilling system shows great promise for seismic reinforcement.

Using the check dam deposit for an individual event to document the sources and erosional loss of sediment-associated organic carbon from a small catchment on the Chinese Loess Plateau

Information on the sources and fate of organic carbon mobilized by soil erosion is crucial for understanding the impact of erosion on carbon (C) cycling. However, few studies have evaluated this in low-order stream systems. In this study, we adopted a novel approach, that used the sediment deposited behind a check dam constructed at the outlet of the Fengzigou catchment (0.91 km2) on the Chinese Loess Plateau by a single high magnitude storm event, to simplify the field sampling requirements. The total sediment-associated organic carbon (TOC) was fractionated into particulate organic carbon (POC) and mineral associated organic carbon (MOC). These results were combined with those from a sediment source tracing exercise. This made it possible to explore further the source and loss of the sediment-associated organic carbon. The results showed that the inter-gully areas contributed the most eroded TOC (52.3 ± 7.6 %) and, together with the gully walls, represented the main TOC source. The primary contributor of the POC fraction in the deposited sediment was the inter-gully areas (80.5 ± 12.6 %), whereas the gully walls were the main contributor of the MOC fraction (54.9 ± 10.2 %). The total output of sediment produced by the event was 1304 ± 48 t and the equivalent value for sediment-associated TOC was 2.94 ± 0.26 t, of which the POC fraction accounted for 27.6 ± 3.6 % and the MOC fraction 72.4 ± 9.8 %. The TOC lost (0.3 ± 0.02 t) through the mobilization and delivery processes was 10.2 ± 1.2 % of the TOC mobilized by erosion, and the lost carbon was dominated by the POC fraction (86.7 ± 8.8 %). The specific TOC output from the catchment associated with the event documented was 0.3 t km−2. This work demonstrates the potential for erosion-induced carbon redistribution to provide a source for atmospheric CO2 in the study area.

Analysis of the flow induced vibration transition sustained by a hydrofoil

Hydrofoils sustain severe flow induced vibrations when a hydrodynamic excitation source couples with a natural frequency, a phenomenon called lock-in responsible for early fatigue and acoustic radiations. The present paper focuses on the fluid-structure interaction during the transition between a non-resonant and a lock-in regimes. Tests were performed in the hydrodynamic tunnel of the French Naval Academy Research Institute with a truncated NACA 66-306 hydrofoil for chord-based Reynolds numbers ranging between 255000 and 374000 at zero angle of attack. Laser vibrometry, particle image velocimetry and spectral proper orthogonal decomposition were used to investigate the fluid-structure interaction mechanisms. The analysis has highlighted a transition between a low magnitude vibration regime occurring at Reynolds 255000 and a lock-in regime occurring at Reynolds 374000. A primary excitation source has been associated with Karman vortex shedding. Also, during the lock-in, a specific type of vortices is observed at a characteristic frequency equal to twice the Karman vortex shedding frequency. Also, a flow recirculation region located in close vicinity of the trailing-edge is reinforced at this particular regime. The understanding of the mechanisms leading to high magnitude vibrations will reduce the acoustic radiations and enhance the efficiency of next generation hydrofoils.

Associations Between Pelvis, Trunk, and Shoulder Girdle Muscle Activity; Age; and Scores During the Closed Kinetic Chain Upper Extremity Stability Test in Baseball Pitchers

OBJECTIVE: To evaluate associations between muscle activity, age, and scores on the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST). DESIGN: Quasi-experimental. METHODS: Pelvic, trunk, and shoulder girdle surface electromyography (sEMG) and kinematic data were measured in 21 high school and college male baseball pitchers (17.4 ± 2.0 years, 184.4 ± 5.7 cm, 78.4 ± 14.2 kg) while they performed the CKCUEST. Mean sEMG data were computed while in sole support on the throwing-arm side (TS) as the glove-arm side (GS) was horizontally translating. Correlations and local regressions were used to assess associations and general patterns between mean sEMG data, age, and scores. RESULTS: TS serratus anterior, TS external oblique, GS serratus anterior, and TS gluteus medius had the highest mean sEMG data. Low-to-high significant correlations were found between proximal muscle groups. Correlations with the highest magnitudes in descending order were TS external oblique and TS gluteus maximus, TS external oblique and TS serratus anterior, and GS external oblique and TS gluteus medius. Small significant associations were observed between other muscle groups and age; there were no associations between muscle activity and test performance. CONCLUSION: Associations were observed between mean muscle activity among muscle groups and age but not test outcome. JOSPT Open 2024;2(4):297-305. Epub 7 June 2024. doi:10.2519/josptopen.2024.1023