Topographic Zone Research Articles

Source fingerprinting sediment loss from sub-catchments and topographic zones using geochemical tracers and weathering indices

Application of sediment source fingerprinting techniques to generate reliable information on sediment sources is growing, because of the global environmental importance of elevated fine-grained sediment mobilisation and delivery to rivers. Despite the application of fingerprinting at different spatial scales (e.g., land use types, geological units, and tributary sub-catchments), it has rarely been used to investigate the sediment contribution of topographic zones. The application of sediment sourcing techniques to topographic zones can be helpful in better understanding the spatial distribution of sediment sources within a catchment and the contribution of different topographic features to sediment production and transport. Against this background, this study assessed both topographic zone and tributary sub-catchment spatial sediment sources in the Kan River catchment, Iran. For this purpose, targeted sampling was performed for each classification of spatial sediment sources, and different tracers (geochemical, elemental ratios, and weathering indices) were measured for 80 surface soil samples collected in topographic zones, 20 bed sediment samples collected in sub-catchments, and 11 suspended sediment samples retrieved at the outlet of the main catchment. Three new statistical approaches were applied to identify composite signatures for spatial sediment source discrimination. These approaches combined the Kruskal-Wallis H-test with Particle Swarm Optimization (KW-PSO), Multi-Layer Perceptron (KW-MLP), and Radial Basis Function (KW-RBF) algorithms. A Bayesian un-mixing model was used to apportion the spatial sediment sources. The three composite signatures identified for elucidating the contributions from either classification of spatial sources generated consistent results. The results clarified that the median contribution from topographic zone 1 equated to it being the major spatial sediment source on the basis of topographic zones, with the contributions estimated at 57%, 49%, and 52% (5%-95% uncertainty range) based on the KW-PSO, KW-MLP and KW-RBF signatures, respectively. In terms of the tributary sub-catchments, the Sangan sub-catchment was identified as the dominant spatial sediment source, with corresponding estimated median contributions of 84%, 83%, and 97%, respectively. A combination of weathering indices and elemental fingerprint properties generated statistically robust composite signatures, providing further evidence that the former can augment more conventional tracers. The predicted source proportions can be explained by topographic characteristics from the digital elevation model of the different spatial topographic zones. Therefore, we conclude that topographic features can be an effective predictor of sediment sources.

Long-term impact of low-energy femtosecond laser and manual cataract surgery on macular layer thickness: A prospective randomized study.

To evaluate change in retinal layers 18 months after femtosecond laser-assisted cataract surgery (LCS) and manual cataract surgery (MCS) in a representative age-related cataract population using artificial intelligence (AI)-based automated retinal layer segmentation. This was a prospective, randomized and intraindividual-controlled study including 60 patients at the Medical University of Vienna, Austria. Bilateral same-day LCS and MCS were performed in a randomized sequence. To provide insight into the development of cystoid macular oedema (CME), retinal layer thickness was measured pre-operatively and up to 18 months post-operatively in the central 1 mm, 3 mm and 6 mm. Fifty-six patients completed all follow-up visits. LCS compared to MCS did not impact any of the investigated retinal layers at any follow-up visit (p > 0.05). For the central 1 mm, a significant increase in total retinal thickness (TRT) was seen after 1 week followed by an elevated plateau thereafter. For the 3 mm and 6 mm, TRT increased only after 3 weeks and 6 weeks and decreased again until 18 months. TRT remained significantly increased compared to pre-operative thickness (p < 0.001). Visual acuity remained unaffected by the macular thickening and no case of CME was observed. Inner nuclear layer (INL) and outer nuclear layer (ONL) were the main causative layers for the total TRT increase. Photoreceptors (PR) declined 1 week after surgery but regained pre-operative values 18 months after surgery. Low-energy femtosecond laser pre-treatment did not influence thickness of the retinal layers in any topographic zone compared to manual high fluidic phacoemulsification. TRT did not return to pre-operative values 18 months after surgery. The causative layers for subclinical development of CME were successfully identified.

Stability of miniscrews depending on the anatomical and topographic zone of localization during orthodontic treatment

During orthodontic treatment, miniscrews are used as additional hardware to create skeletal support for more efficient movement of teeth on braces and aligners. The most common areas for placing miniscrews are the alveolar ridge of the upper jaw, the retromolar region, the interradicular space, and the subzygomatic ridge. Purpose of the study: to evaluate the influence of the anatomical and topographic localization of steel and titanium miniscrews on their stability in bone tissue during orthodontic treatment using fixed orthodontic appliances Materials and methods. An examination, photo proto-col, and analysis of cone beam computed tomography (CBCT) were performed in 60 patients who had a history of having a miniscrew placed in the interradicular and retromolar areas, and the subzygomatic ridge. An analysis of the stability of miniscrews was carried out immediately after the operation of installing a miniscrew, performed under local anesthesia, and during the entire period of orthodontic treatment with fixed appliances. Results.The most common primary and secondary rejection of titanium miniscrews was observed in the retromolar re-gion (6.2 and 18.7%, respectively), steel ones — in the subzygomatic ridge (50 and 37.5%, respectively). Con­clusion: The maximum stability of miniscrews when treating patients with a fixed technique using a ske-letal support is observed in the interroot region. It is necessary to carefully plan the site of miniscrew insertion based on CBCT data, taking into account the individual characteristics of the bone tissue structure to reduce the risk of loss of skeletal support

Interplay between tectonics and surface processes in the evolution of mountain ranges: Insights from landscape dynamics, uplift, and active deformation of Talesh Mountains (NW Iranian Plateau margin)

Drainage divides are dynamic features of a landscape that migrate over time during the development of river networks. In this study, we focused on the geomorphic response of a landscape to the interaction among tectonics, climate, and lithology in the Talesh Mts. along the northwest of the Iranian Plateau. The footprints of these competing forces have been analyzed by divide stability analysis and applying χ, χQ, and Gilbert metrics. Additionally, we examined the effects of bedrock erodibility on landscape evolution processes by measuring the mechanical rock strength of the lithological units in different sectors of the mountain range. The distribution of the χ values suggests a disequilibrium of the drainage networks across the whole main divide and its tendency to migrate towards the interior of the plateau. In contrast, Gilbert metrics, which focuses on a narrow topographic zone across the divide, suggest that the uppermost divide in the northern and southern Talesh Mts. is stable. Moreover, asymmetry in Gilbert metrics across the central part of the range suggests that the divide might be migrating towards the plateau interior. The possible scenario for the whole divide's behavior is associated with the contrasting erosion rates across the divide. In the northern and southern sectors of the Talesh Mts. range, the erosional wave related to the most recent uplift pulses has not reached the divide yet. Mechanism of topographic rejuvenation is controlled by heterogeneous uplift of strong bedrock units in the northern and southern sectors, and weak bedrock units outcropping in the central sector, initiated topographic rejuvenation largely in the central Talesh Mts. Parallelly, the precipitation has a limited effect in assisting and magnifying the divide mobility, reorganization, and landscape transience. In general, we can infer that divide is in a transient state due to the spatially varying rock uplift and bedrock erodibility.

Factors affecting topographic thresholds in gully erosion occurrence and its management using predictive machine learning models

Soil degradation induced by gully erosion represents a worldwide problem in the many arid and semi-arid countries, such as Iran. This study assessed: (1) the importance of variables that control gully erosion using the Boruta algorithm, (2) the relationship among causative variables and gullied locations using the evidential belief function model (EBF), and (3) gully erosion development using the algorithms of boosted regression tree (BRT) and support vector machine (SVM). Based on the results of the Boruta algorithm, slope, land use, lithology, plan curvature, and elevation were the most important factors controlling gully erosion. The results of the EBF model showed the predominance of gully erosion on rangeland and loess-marl deposition. The predominance of gullied locations on the concave positions, with the slope of 5°–20° in the vicinity of drainage lines, illustrates a preferential topographic zone and, therefore, a terrain threshold for gullying. The correlation of gullied locations with rangelands and weak soils in concave positions demonstrates that the interactions among soil characteristics, topography, and land use stimulate a low topographic threshold for gullies development. These relationships are consistent with the threshold concept that a given soil, land use, and climate within a given landscape encourage a given drainage area and a critical soil surface slope that are necessary for gully incision. Furthermore, the BRF-SVM had the highest efficiency and the lowest root mean square error, followed by BRT for predicting gully development, compared with LN-SVM algorithm. The application of two machine learning methods for predicting the gully head cut susceptibility in northern Iran showed that the maps generated by these algorithms could provide an appropriate strategy for geo-conservation and restoration efforts in gullying-prone areas.

Case series of traumatic neglected Extensor Hallucis Longus lacerations: choice of surgical treatment based on injury type.

Extensor Hallucis Longus (EHL) tendon rupture is a rare injury of the foot, representing only 1% of overall tendon rupture. Early diagnosis and surgical repair are recommended but there is still no consensus regarding the ideal treatment. The purpose of this study was to evaluate a case series of patients with neglected extensor hallucis longus (EHL) tendon rupture. We report a case series of 3 patients affected by traumatic neglected EHL lacerations treated with reconstructive surgery using tissue scaffolds, between November 2019 and May 2020. Demographics data, mechanism of injury, zone of injury, tendon gap, time to surgery, type of surgical repair, preoperative and postoperative functional score were collected with a minimum follow-up of 8 months. The zone of injury (according to Al-Qattan classification) involved was in 1 case zone 2, in 1 case zone 4 and in the last case zone 5. The mean value of intraoperative tendon gap was of 3,4 cm. The elapsed time from injury to surgery was an average of 3,3 months. One tendon transfer surgery and two primary repairs with Krakow fashion were performed, all augmented with tissue scaffolds. The mean preoperative and postoperative American Orthopedic Foot and Ankle Society (AOFAS) scores were, respectively, 43 and 97. Our results highlight good functional result and satisfaction with active extension of the hallux restored in all patients. According to our experience, we recommend choosing reconstruction technique basing on the topographic zone of lesion and intraoperative tendon gap.

Topographic and anatomical features of muscular and vascular structures in lateral cervical region during prenatal period of human ontogenesis

Background. One of topical areas of morphological research is features of topographic a relationships of the vascular, nervous, muscular, fascial and cartilaginous structures of the neck in prenatal period of human ontogenesis, as data on their formation at different stages of development will improve diagnostic methods of visualization and surgical correction of congenital and acquired pathologies of head and neck. Objective. To find out the peculiarities of synthopia of vascular and muscular structures of the lateral cervical region in human prefetuses. Methods. 9 human prenatal specimens aged 9-12 weeks of prenatal development have been studied by using a set of morphological methods, according to existing bioethical norms. Results. During 9th week of development, bony and musclar boundaries of the lateral triangle of the neck, the carotid vagina, and the components of the vascular-nervous bundle of the neck have been determined. Within the carotid triangle, the external carotid artery is located superficially; it is crossed frontally by the cervical branch of facial nerve and the sublingual nerve. The superior thyroid artery departs from the external carotid artery at the level of the cartilaginous model of the large horns of hyoid bone and passes to the rudiment of thyroid gland. Retropharyngeal space is found at 9th week of development, moderately filled with adipose tissue. The anterior vertebral plate of the cervical fascia forms the bottom for posterior triangle of neck. Conclusion. The lateral cervical region in human prefetuses is represented by a multilayered topographic zone with formed boundaries and contents. Cervical fascia forms carotid vagina within the carotid triangle, and pharyngeal space. The course of blood vessels and nerves within the lateral cervical region is variable. Three-dimensional reconstructions of prefetuses serve as evidence of the early formation of definitive topographic connections within early bony and cartilaginous models in relation to the muscles of the anterior and lateral cervical regions.

Spatial and Temporal Characteristics of PM2.5 Sources and Pollution Events in a Low Industrialized City

In recent years, cities in southern China have experienced severe air pollution, despite having few sources of pollutants. To study the pollution characteristics of PM2.5 in these “low industrialized” cities, a numerical method based on the HYSPLIT4 Model and Kriging Spatial Interpolation Technology was established. Simulation results showed that the PM2.5 pollution in Guilin was affected by both internal and external sources. The backward air mass trajectory from July 2017 to June 2018 was simulated using the HYSPLIT model. The cluster analysis results indicated that the direction of trajectory ? accounted for 63.09% of the air pollution in the city. The average concentration of PM2.5 pollution was 45.94 ?g.m-3. The pollutant originated from the “Xiang-Gui Corridor.” The location of the sources was collocated with high industry regions. The spatial characteristics of the four pollution processes in the winter of 2017 were analyzed using a spatial interpolation method. The results showed that the transport of air masses in the direction of trajectory ? was obstructed by a mountain system in the northeast. Therefore, two air pollution accumulation centers and a topographic weakening zone dominated by internal and external sources were formed. It can be inferred that the air pollution in Guilin is affected by both internal and external factors. These results provide important theoretical and technical support for regional air pollution control and environmental protection.

Nonsequential Response in Mountainous Areas of Southwest China

Nonsequential response is the phenomenon where the change of soil water content at the lower layer is larger than that of the upper layer within a set time interval. It is often ignored because of the lack of spatially distributed measurements at the watershed scale, especially in mountainous areas where extensive monitoring network is expensive and difficult to deploy. In this study, the subsurface nonsequential response in a mountainous watershed in Southwest China was investigated by combining field monitoring and numerical simulation. A physics-based numerical model (InHM) was employed to simulate the soil water movement to explore the occurrence of the subsurface nonsequential response. The topographic wetness index [TWI = ln (a/tan b)] was used to distinguish the topographic zone corresponding to the nonsequential response at different depths. The nonsequential response mainly came from the subsurface lateral flow initiated at the soil–bedrock interface or at a relatively impermeable layer. The results showed that the occurrence depth of the nonsequential response increased with precipitation intensity when the time since last event was more than 24 h and the total amount of this event exceeded 37 mm. During a rainfall event, the nonsequential response occurred at the middle layer in the hillslope zone and the deep soil layer beneath the channel. In case of a rainfall event with two peaks, the region observed with nonsequential response expanded. The soil layer at the interface of the bedrock could be saturated quickly, and became saturated upward. This kind of nonsequential response can be observed on the hillslope at the beginning of rainfall events, and then found beneath stream channels afterward. Furthermore, nonsequential response could also happen after rainfall events. The results improved our understanding of nonsequential response and provided a scientific basis for flash flood research in mountainous areas.

Centrifuge Studies of Topographic Effects: Parametric Investigation

ABSTRACTThis article presents the results of a comprehensive geotechnical centrifuge experimental program to investigate topographic effects across a series of single-sided slopes. The experimental campaign considered a range of governing factors, including slope inclination and ground-motion amplitude, frequency content, and duration. The testing program was nondestructive, allowing the centrifuge models to be subjected to over 140 different ground motions. Clear evidence of topographic effects, including amplification and deamplification of ground motion, were observed. Topography modified the frequency content and amplitude of the ground motion such that at the slope crest (1) peak ground accelerations ranged from 50% less than to 200% greater than the free-field, and (2) ground-motion mean square frequency shifted by as much as 55%. Higher topographic amplification levels lead to a larger topographic zone of influence, which, on average, spanned a distance equal to the slope height (H) behind and 2H in front of (toward slope) the slope crest. Physical modeling in the centrifuge proved to be a powerful experimental technique for generating empirical data to analyze topographic effects in a systematic and repeatable manner.

Centrifuge Studies of Topographic Effects: Dynamic Response Mechanisms

ABSTRACTThis article presents analyses of select experiments from a comprehensive geotechnical centrifuge program to investigate topographic effects in single-sided slopes. A unique benefit of centrifuge modeling is that it provides high-resolution measurements of a thoroughly characterized “site” while fully preserving physical processes. The analyses were performed in the time and time–frequency domains to investigate mechanisms that produced the topographic effects. The results indicate that resonance at the slope’s topographic frequency is the principal driver of topographic effects. Site and topographic effects may combine at a slope crest to produce high levels of overall amplification. When topographic amplification occurs, the topographic zone of influence will vary depending on the ground-motion wavelength and the influence of phasing when multiple frequency components are present in the ground motion. Ground-motion complexities such as phase differences in response between a slope and the adjacent free field may serve to either amplify or de-amplify earthquake ground motion near a slope.

Pliocene‐Pleistocene Stratigraphy and Sea‐Level Estimates, Republic of South Africa With Implications for a 400 ppmv CO2 World

AbstractThe Mid‐Pliocene Warm Period (MPWP, 2.9 to 3.3 Ma), along with older Pliocene (3.2 to 5.3 Ma) records, offers potential past analogues for our 400‐ppmv world. The coastal geology of western and southern coasts of the Republic of South Africa exposes an abundance of marine deposits of Pliocene and Pleistocene age. In this study, we report differential GPS elevations, detailed stratigraphic descriptions, standardized interpretations, and dating of relative sea‐level indicators measured across ~700 km from the western and southern coasts of the Cape Provinces. Wave abrasion surfaces on bedrock, intertidal sedimentary structures, and in situ marine invertebrates including oysters and barnacles provide precise indicators of past sea levels. Multiple sea‐level highstands imprinted at different elevations along South African coastlines were identified. Zone I sites average +32 ± 5 m (six sites). A lower topographic Zone II of sea stands were measured at several sites around +17 ± 5 m. Middle and late Pleistocene sites are included in Zone III. Shoreline chronologies using 87Sr/86Sr ages on shells from these zones yield ages from Zone I at 4.6 and 3.0 Ma and Zone II at 1.04 Ma. Our results show that polar ice sheets during the Plio‐Pleistocene were dynamic and subject to significant melting under modestly warmer global temperatures. These processes occurred during a period when CO2 concentrations were comparable to our current and rapidly rising values above 400 ppmv.

Investigation of WRF Microphysics Schemes and Dynamics During an Extreme Precipitation Event in East Idaho

Background:The 26 December 2003 snowstorm was a rare and long-lived weather system that affected east Idaho. Light snow began falling Christmas night, became steadier and heavier during the next day, and tapered off during the morning on the 27th. Snowfall estimates of 20.3-38.1 cm (8.0-15.0 in) were observed over a 24-hour period on 26 December 2003 in the lower part of the Snake River Plain, paralyzing local communities and transportation centers with snowdrifts and poor visibilities.Methods:The Weather Research and Forecasting Unified Environmental Modeling System was used to conduct a sensitivity study of five precipitation microphysics schemes at two grid scales during the event.Results:A comparison of the model accumulated total grid scale precipitation at 12-km and 4-km scales with the observed precipitation at several stations in the lower plain, indicated small negative biases (underprediction) in all of the schemes. The Purdue-Lin and Weather Research and Forecasting Double-Moment 6-Class microphysics schemes contained the smallest root mean squared errors.Conclusion:The Purdue-Lin and Weather Research and Forecasting Double-Moment 6-Class schemes provided several insights into the dynamics of the snowstorm. A topographic convergence zone, seeder-feeder mechanism, and convective instability were major factors contributing to the heavy snowfall in the lower plain.

Resistive index of ophthalmic artery correlates with retinal pigment epithelial alterations on spectral domain optical coherence tomography in diabetic retinopathy

BackgroundRetinal pigment epithelium (RPE) plays a significant role in maintenance of integrity of retinal photoreceptors and choriocapillaries. RPE derives its blood supply through ophthalmic artery (OA) via choriocapillaries. RPE topographic alterations have been observed to be associated with severity of retinopathy. The present study was undertaken to assess the correlation between resistive index (RI) of the OA with RPE topographic alterations on Spectral-Domain optical coherence tomography (SD-OCT), to our knowledge, it is for the first time.MethodsA tertiary care center based cross-sectional study was undertaken after informed consent. Sample size was calculated using 95% confidence interval. Seventy five consecutive cases of type 2 diabetes mellitus between the ages of 40 and 70 years were included. The cases were divided into three groups according to Early Treatment Diabetic Retinopathy Study classification: diabetes mellitus with no retinopathy (No DR) (n = 24); non-proliferative diabetic retinopathy (n = 27); and proliferative diabetic retinopathy (n = 24). Healthy control subjects of similar age group were included (n = 24). RI in OA was studied using Color Doppler imaging. Grades of RPE topographic alterations and retinal photoreceptor ellipsoid zone (EZ) disruption were studied using SD-OCT. Data was analysed using Chi square (χ2) test, analysis of variance (ANOVA), Pearson correlation analysis and Neuman–Keuls test.ResultsLogMAR best corrected visual acuity was found to increase significantly with the severity of DR (F = 105.74, p < 0.001). ANOVA revealed a significant increase in RI of OA (F = 14.23, p < 0.001) with severity of diabetic retinopathy. χ2 test revealed significant increase in grades of RPE alterations (χ2 = 71.83, p < 0.001) and EZ disruption (χ2 = 60.59, p < 0.001) with the severity of diabetic retinopathy. Pearson correlation analyses revealed a significant positive correlation between RI of OA with grades of RPE alterations (r = 0.48, p < 0.001) and also between grades of RPE alterations and EZ disruption (r = 0.82, p < 0.001).ConclusionsDecrease in ocular blood flow resulting from an increase in RI of OA correlates with severity of DR and grades of topographic alterations in RPE. Integrity of EZ was observed to be dependent on RPE.

Early recovery process and restoration planning of burned pine forests in central eastern Korea

In central eastern Korea, there has been a continued effort to sustain pine forests because of their value for wood and mushroom production, as well as for other resources. Through the analysis of previously burned areas, we clarified the effects of fire on vegetation dynamics of pine forests by measuring changes in species composition, population structure, and the growth rates of major tree species. Vegetation analysis was conducted on a series of 100 m2 plots established in Korean red pine (Pinus densiflora Siebold. & Zucc.) and Mongolian oak (Quercus mongolica Fisch. Ex Ledeb.) forests situated in three different topographic positions on slopes where fire severity varied. We confirmed that most pine trees will succumb to even a surface fire, whereas oak may be killed following high intensity or infrequent fires but will sprout and become dominant. Complete protection from fire favors other, more shade-tolerant deciduous hardwoods. Different restoration plans apply, based on observed vegetation responses for each topographic zone. Near the ridge top, where pine seed sources are most limited, it may be necessary to restore pine forests by planting and to control competing shrubs and herbs. At the mountain foot, where exotic species and species modified by hybridization have invaded aggressively, restoration that involves the introduction of natural vegetation is required. Mid-slope sites, where pine has been replaced by natural vegetation dominated by Mongolian oak, do not require any form of restorative treatment.

Semi-automated object-based landform classification modelling in a part of the Deccan Plateau of central India

ABSTRACTLandform mapping holds significance in governing boundary conditions for the underlying processes operative in the fields of natural resource management, yet the automation in recognizing landform occurrence remains difficult. Geospatial object-based image analysis (GEOBIA) technique has evolved as a promising tool for addressing the issue. Majority of the GEOBIA-based landform classification studies document generic approach. The present study undertaken in Katol Tehsil of Nagpur District, a part of Deccan Plateau of central India aims at knowledge-based modelling through a multi-scale mapping workflow comprising multi-resolution segmentation (input raster dataset of IRS-P6 LISS-IV image and Cartosat-1 digital terrain model), knowledge-based classification, and accuracy assessment against a reference landform map. Contour- and drainage-based relative topographic position zone is derived in a novel attempt. Finally, knowledge-based rules are framed using the primary terrain parameters of elevation, slope, profile curvature, and drainage for deriving final output. The results of landform classification indicate the dominance of erosive landform over depositional one; maximum area of 6244 ha being under pediment. An accuracy assessment exercise is carried out in a watershed occurring in the study area, which shows very good statistical agreements between modelled and reference landforms including partial detection. The key constraint of this knowledge-based modelling is its limited adaptability to only localized conditions. However, such kind of object-based and knowledge-based analyses have immense potential with the increasing availability of finer resolution remote-sensing data products that demand the alternative paths of deriving objects that are made up of several pixels.

Browsing intensity of herbaceous forbs across a semi-arid savanna catenal sequence

Ecological models to explain savanna heterogeneity and functioning weakly represent herbaceous forbs, which inevitably created knowledge gaps regarding the diversity and ecology of forbs. Forbs constitute over 70% of semi-arid savanna species richness. The aim of this study was therefore to (i) identify forb species that potentially form part of herbivore diet, and (ii) determine forb browsing intensity across a granitic savanna catenal sequence. Localized contrasts between nutrient-poor dystrophic uplands and nutrient-rich eutrophic bottomlands led us to predict that bottomlands would host forb assemblages dominated by browsed species. Forbs contributed to 78% of the total herbaceous layer species richness, of which 43% were browsed at varying intensities along the catenal sequence. Each topographic zone hosted a unique assemblage of browsed forbs, although browsing intensity was highest in the sodic bottomlands. Some browsed forbs formed prostrate, stoloniferous covers on the bottomlands, creating a lawn type dominated by forbs. Results presented here are the first to identify browsed forb species and to illustrate the turnover in browsing intensity of forbs across a semi-arid savanna catenal sequence. Our results add weight to the need to include herbaceous forbs in savanna management models to better understand savanna resource ecology and heterogeneity.

Glenoid subchondral bone density distribution in male total shoulder arthroplasty subjects with eccentric and concentric wear

Glenoid component loosening in total shoulder arthroplasty may be prevented by component placement on a congruent and adequate bony surface. Glenoid subchondral bone density (SBD) variability may be correlated with this concept. This study analyzed the 3-dimensional distribution of glenoid SBD in total shoulder arthroplasty patients with osteoarthritis. Three-dimensional computed tomography osteoabsorptiometry (CT-OAM) was performed in 42 men (21 with eccentric and 21 with concentric wear patterns) with glenohumeral arthritis. Glenoid SBD was measured from the joint surface based on 5 clinically relevant topographic zones. The correlation of the wear pattern with the SBD distribution was investigated. The glenoid subarticular layers could be separated into distinct regions: calcified cartilage (≤ 1.5 mm), subchondral plate (2-4.5 mm) and cancellous bone (≥ 5 mm). There were significant differences in SBD among these layers within and between patients with concentric and eccentric wear patterns. In concentric glenoids, the SBD distribution was homogeneous, with greater mineralization in the central zone, 1,749.1 ± 162.3 Hounsfield units (HU) (at 2.5 mm), compared with the posterior, anterior, and superior zones (P < .001). In the eccentric group, the SBD distribution was inhomogeneous. Mineralization was greatest in the posterior zone, 1,739.0 ± 172.6 HU (at 2.5 mm), followed by the inferior zone, 1,722.1 ± 186.6 HU (at 3 mm). This study represents the first study using CT-OAM to evaluate the 3-dimensional SBD distribution of the glenoid vault for different arthritic wear patterns. The study findings indicate that the SBD distribution is dependent on (1) depth from the articular surface, (2) topographic zone, and (3) wear pattern. CT-OAM may be an effective tool to assist in preoperative planning for shoulder arthroplasty.

Spatial Data Clustering and Zonation of Earthquake Building Damage Hazard Area

Research conducted with the aim to develop spatial data cluster and analyse the characteristics of each cluster of data in order to develop spatial zonation of building damage hazard caused by the earthquake in the city of Banda Aceh. The data used consists of the data peak ground acceleration (PGA), lithology and topographic zone data with the four phases of the study consisted of data normalization with min-max method, determination of optimum data group with the connectivity index, Dunn index and the Silhouette index, clustering of data with the k-Means algorithm and the data interpolation using kriging algorithm to construct the zonation of hazard area. The optimum numbers of clusters used in these researches are two, with the first 170 data largely concentrated at a distance of less than 0.1 to 0.5 from the cluster centre and the second 55 others data concentrated at a distance of 0.3 - 0.5 from the cluster centre. Banda Aceh and surrounding areas can be spatially divided into two classes of potential building damage caused by the earthquake with high hazard class building damage are generally located near the coastline.

Sediment yield in Europe: Spatial patterns and scale dependency

Our understanding about the regional variation of Sediment Yield (SY) in Europe and its scale dependency currently relies on a limited number of data for mainly larger river systems. SY is the integrated result of all erosion and sediment transporting processes operating in a catchment and is therefore of high value for environmental studies and monitoring purposes. Most global assessments of SY consider catchment area (A), climate and topography as the main explanatory variables. However, it is still unclear if these factors also control regional variations of SY within Europe. This paper aims at bridging this gap. Therefore, we i) present a large database of SY-values which was constructed through an extensive literature review; ii) describe the spatial patterns of SY across Europe; and iii) explore its relation with A, climate, and topography.In total, sediment yield data from 1794 different locations throughout Europe were collected (507 reservoirs and 1287 gauging stations), representing a minimum of 29,203 catchment-year data. Only SY-data measured at gauging stations or derived from reservoir siltation rates over a period of a minimum of one year were included in the database. This database comprises a large range of catchment areas (A): i.e from small upland catchments (≥0.01km²) to major European river basins (≤1,360,000km²). An overview of the collected SY-data is provided and sources of uncertainty on the available data are discussed.Despite potentially large uncertainties on several of the individual SY-values, analysis of this database indicates clear spatial patterns of SY in Europe. The temperate and relatively flat regions of Western, Northern and Central Europe generally have relatively low SY-values (with ca. 50% of the SY<40tkm−2yr−1 and ca. 80% of the data <200tkm−2yr−1), while Mediterranean and Mountainous regions generally have higher SY-values (with around 85% of the SY-data >40tkm−2yr−1 and more than 50% of the data >200tkm−2yr−1). These differences are attributed to a combination of factors, such as differences in climate, topography, lithology and land use. Although larger differences in SY were found between the climatic regions than between topographic zones, it is currently difficult to identify the individual importance of the various controlling factors of SY.SY–A relationships were calculated for the entire dataset and for subgroups stratified according to the measurement method (gauging stations or reservoir surveys), range of the catchment area, climatic region, topographic zone of the river outlet, and major European river system. Although typically a negative relationship between SY and A is expected due to a decrease in topsoil erosion rates on more gentle slopes and an increase in sediment deposition with an increase in catchment size, this relationship was found to be generally very weak and subject to a lot of scatter. Furthermore, results illustrate important differences in scale dependency: whereas a weak but significant negative trend is generally observed for the temperate and relatively flat regions, no significant or even positive trends were observed in mountain regions and Mediterranean Europe. When only larger river catchments (i.e. >100km² and especially >10,000km²) are considered, catchment area exerted a larger control on SY. These findings confirm previous studies and indicate that the relationship between SY, spatial scale and other controlling factors is often complex and non-linear.