Local Ground Research Articles

Dynamics of fish larvae recruitment in the hydrographic basin of the Paraguay River in western Brazil

Abstract The conservation of fish assemblages depends on the longitudinal and lateral connectivity between riverine habitats, in particular during the breeding season and the initial development. This study investigated the composition and spatio-temporal structure in the ichthyoplankton of the hydrographic basin of the Paraguay River in western Brazil to identify the local spawning grounds and the importance of the longitudinal connectivity of economically valuable migratory species. Data were collected at 10 sites between two breeding seasons (2017/2018 and 2018/2019). Were collected 8,635 larvae, representing 55 taxa in 25 families, including the migratory species Brycon hilarii, Hemisorubim platyrhynchos, Piaractus mesopotamicus, Prochilodus lineatus, Pseudoplatystoma spp., Salminus brasiliensis, Sorubim lima, and Zungaro jahu, which are important fishery resources, with the highest larval densities being recorded between November and January. The Sepotuba, Paraguay, Jauru, and Cabaçal rivers were the areas of greatest connectance, and should thus be considered critical for the conservation of the longitudinal connectivity of this fluvial system, indicating that the migratory species spawn upriver. More efficient fisheries management mechanisms are needed, respecting the spawning period of migratory species, maintaining quality and longitudinal connectivity between habitats, and characteristics necessary for successful larval recruitment.

NATURAL PROCESSES AS JUSTIFICATION FACTORS FOR DECISIONS ON PORT HYDRAULIC STRUCTURES

The effects of sea waves and currents on harbour hydraulic structures are analysed from published open source data and the characteristics of scour from waves, including tsunami waves, are considered. Local bottom scour threatening the general stability of gravity-type engineering structures can arise under the effect of storm waves and currents, jets from ship propulsion devices and tsunami waves near hydraulic engineering structures. The types of scour mechanisms from sea waves have been investigated, i.e., local, general, and overtopping scour. There is a lack of sufficient measurement data for general scour to verify the calculation methods. Generally, general scour does not damage a structure, although it can contribute to its destruction by other types of scour when they overlap. Therefore, existing studies mainly focus on the analysis of local scour. The relationship between local scour and ground liquefaction and their influence on the stability of marine hydraulic structures is established. Failure mechanisms of hydraulic structures due to erosion by tsunami waves are analyzed: leeward and seaward toe scour, crown armour failure, parapet wall failure, sliding failure. The tsunami wave scour enhancement parameter is given, which is the fraction by which the pore pressure gradient reduces the frictional forces resisting scour. Significant ground instability occurs when the scour amplification parameter Λ exceeds a value of 0.5 (Λ ≥ 0.5). The parameter Λ can be used to assess areas where instantaneous liquefaction may be responsible for scour and sediment movement and to further recalculate erosion depths obtained without considering liquefaction. Liquefaction from a tsunami wave may penetrate up to 28% of the maximum erosion depth due to shear forces. The liquefaction phenomenon may occur due to a sudden drop in the water level in the area of return flow concentration. Consequently, the liquefaction phenomenon must be considered in the stability and erosion analysis around the structure.

Data Offloading in UAV-Assisted Multi-Access Edge Computing Systems Under Resource Uncertainty

In this paper, a novel data offloading decision-making framework is proposed, where users have the option to partially offload their data to a complex Multi-access Edge Computing (MEC) environment, consisting of both ground and UAV-mounted MEC servers. The problem is treated under the perspective of risk-aware user behavior as captured via prospect-theoretic utility functions, while accounting for the inherent computing environment uncertainties. The UAV-mounted MEC servers act as a common pool of resources with potentially superior but uncertain payoff for the users, while the local computation and ground server alternatives constitute safe and guaranteed options, respectively. The optimal user task offloading to the available computing choices is formulated as a maximization problem of each user’s satisfaction, and confronted as a non-cooperative game. The existence and uniqueness of a Pure Nash Equilibrium (PNE) are proven, and convergence to the PNE is shown. Detailed numerical results highlight the convergence of the system to the PNE in few only iterations, while the impact of user behavior heterogeneity is evaluated. The introduced framework’s consideration of the user risk-aware characteristics and computing uncertainties, results to a sophisticated exploitation of the system resources, which in turn leads to superior users’ experienced performance compared to alternative approaches.

Thinking on Effective Methods of Successful Prediction of Geological Hazards in Shaanxi, China

In the process of human survival and development, it is inevitable to transform the original state of the world, thus forming a contradiction between the earth and the earth. The violent form of this contradiction is geological disasters. Geological disasters pose a threat to human life and property, and cause damage caused by natural or human factors, often causing casualties. The destruction process of geological disasters is usually a gradual process, showing many pre-disaster symptoms, such as local landslides, surface cracks, building deformation, tree skew, and ground sound. Evacuation can be avoided in advance according to the disaster precursors, so as to avoid casualties and achieve successful prediction. By reviewing the general situation of geological disasters in Shaanxi Province and the casualties in 2020, the difficulties in the prevention and control of geological disasters are summarized. In view of these difficulties, an on-site investigation, visit and analysis of geological disaster points and successful forecast points in Shaanxi Province in 2020 were conducted. In addition, combined with actual cases and years of work experience, the successful prediction experience of geological disasters was discussed from 8 aspects. Finally, the “Regulations on the Reward for Successful Geological Disaster Forecasting in Shaanxi Province” was revised in order to improve the successful prediction ability of geological disasters in Shaanxi Province and even the whole country, provide reference for future prevention and control of geological disasters, and effectively protect the safety of people’s lives and property.

Hybrid Forecasting of Wind for Air Pollution Dispersion over Complex Terrain

In case of an unplanned emission event from a nuclear power plant, the local population can be protected more efficiently when valid atmospheric dispersion model results are available. Atmospheric dispersion models use local meteorological variables as inputs. When atmospheric dispersion in the future is being predicted, a forecast of the local meteorological variables is needed. The most important variable in atmospheric dispersion modelling is wind, and accurately predicting ground level winds presents a challenge to numerical weather prediction models. We therefore develop hybrid models for forecasting local ground level wind at a single location where the terrain is complex and the average wind is weak and fluctuating. Wind speed and direction are modelled as west-east and south-north wind components. Each model is composed of a numerical weather prediction model and a Gaussian process statistical model that uses numerical weather predictions as some of its inputs and is trained on historical data to predict the output component. The most advanced Gaussian process models studied are of Gaussian process nonlinear autoregressive model with exogenous input (GPNARX) type. In addition to numerical weather predictions, they also use local meteorological variables, including the output variable, as their inputs. Numerical weather prediction results based on large scale information and fundamental knowledge of the system are thus supplemented by local measurements that better reflect the effects of local topography and land use. The models are tested by prediction and simulation. The wind components predicted by more advanced models are more accurate than raw or post-processed numerical weather prediction results. As an example, a model predicting 2D wind vector 1.5 h in advance achieves a NRMSE of 0.214 if it uses all the immediately available information. This is better than both the persistence model with NRMSE of 0.188 and post-processed NWP with NRMSE of 0.164. This demonstrates that hybrid modelling provides the best weather information for short-term and medium-term atmospheric dispersion forecasting. While the method is motivated by nuclear emission sources, it could also be applied to other pollution.

Habitat area and local habitat conditions outweigh fragmentation effects on insect communities in vineyards

Abstract Fragmentation of habitat, for example by intensive agricultural practices, can be detrimental to local biodiversity. However, it often remains unclear whether such biodiversity declines are caused by loss of habitat area or increased fragmentation, and how habitat quality factors into it. In our study system, vegetated vineyards are typically small, and isolated from one another, potentially limiting the distribution and dispersal of organisms. In a full‐factorial experiment of a priori selected vegetated vineyard patches of differing size and fragmentation, we aimed to disentangle the effects of habitat area (area of vegetated vineyards), habitat fragmentation (number of vegetated vineyards per 100 ha) and field‐scale ground vegetation density on ground beetle, leafhopper and wild bee communities using a combined framework of multiscale and multispecies modelling (Hierarchical Model of Species Communities). We demonstrate variable effects of habitat area, fragmentation and local ground vegetation density on the three insect groups: Increased habitat area at fine scales favours higher species richness of leafhoppers, while local vegetation density boosts species richness of both leafhoppers and ground beetles, whereas no community‐level responses were detected for wild bees. We conclude that increased ground vegetation density at both field and landscape scales (i.e. higher habitat area) favours more diverse and abundant insect communities, while fragmentation effects are highly variable and species specific. In addition, our results highlight that mainly ground beetles and leafhoppers will benefit from simple ground greening measures in vineyards, while for wild bees environmental factors other than the ones tested here may drive community structure. We recommend increasing the number and area of vegetated vineyards (even at small spatial scales) requiring more nature‐friendly farming practices especially regarding a reduction or renunciation from herbicide applications, while the within‐field vegetation density should optimally be intermediate or high to favour a diverse insect community.

Empowering The Magersaren Community: Technology Dissemination For Ground Coffee Added Value Improvement

This paper is aimed to share the community service experiences held at Boro Sumbersari hamlet which is located at 98A UB forest plot. Boro Sumbersari hamlet is inhabited by Magersaren community. The Magersaren community are farmers and forest workers who depend on forestfor their livelihoods. Magersaren has been practicing agroforestry for a long time. They grow Robusta and Arabica coffee among other forest plants. Currently coffee is a favorite beverage, the number of its consumers continues to increase. Many people areinterested in the ground coffee beans made by Magersaren traditionally, but it has not been widely marketed. The purpose of this community service program is to generate an alternative source of Magersaren household income, through the added value improvement of local flavored ground coffee beans they have. The added value of magersaren’s ground coffee beans can be increased through product development technologies such as attractive packaging techniques and the creation of new variants ground coffe beans by adding brown sugar and powdered ginger. The execution of community service activities that have been carried out consists of: 1)program socialization; 2)focus group discussion; 3)production, packaging and management training; 4)small-business starting up; 5)program evaluation. These community service activities are held during the social distancing due to the COVID-19 pandemic. This condition becomes an obstacle to the effectiveness of program implementation. The start-up small business needs to be continuously supported in order to survive through a critical period of business development, especially under economic pressure during the pandemic

A daily and 500 m coupled evapotranspiration and gross primary production product across China during 2000–2020

Abstract. Accurate high-resolution actual evapotranspiration (ET) and gross primary production (GPP) information is essential for understanding the large-scale water and carbon dynamics. However, substantial uncertainties exist in the current ET and GPP datasets in China because of insufficient local ground measurements used for model constraint. This study utilizes a water–carbon coupled model, Penman–Monteith–Leuning Version 2 (PML-V2), to estimate 500 m ET and GPP at a daily scale. The parameters of PML-V2(China) were well calibrated against observations of 26 eddy covariance flux towers across nine plant functional types in China, indicated by a Nash–Sutcliffe efficiency (NSE) of 0.75 and a root mean square error (RMSE) of 0.69 mm d−1 for daily ET, respectively, and a NSE of 0.82 and a RMSE of 1.71 g C m−2 d−1 for daily GPP. The model estimates get a small Bias of 6.28 % and a high NSE of 0.82 against water-balance annual ET estimates across 10 major river basins in China. Further evaluations suggest that the newly developed product is better than other typical products (MOD16A2, SEBAL, GLEAM, MOD17A2H, VPM, and EC-LUE) in estimating both ET and GPP. Moreover, PML-V2(China) accurately monitors the intra-annual variations in ET and GPP in the croplands with a dual-cropping system. The new data showed that, during 2001–2018, the annual GPP and water use efficiency experienced a significant (p<0.001) increase (8.99 g C m−2 yr−2 and 0.02 g C mm−1 H2O yr−1, respectively), but annual ET showed a non-significant (p>0.05) increase (0.43 mm yr−2). This indicates that vegetation in China exhibits a huge potential for carbon sequestration with little cost in water resources. The PML-V2(China) product provides a great opportunity for academic communities and various agencies for scientific studies and applications, freely available at https://doi.org/10.11888/Terre.tpdc.272389 (Zhang and He, 2022).

Method for Determining the Susceptibility of the Track

This paper discusses real-world experiments in which selected ground imperfections were dynamically analysed in terms of track susceptibility for a linear and non-linear system. The imperfections included wheel pressure on local ground irregularities within the railway turnout. In this study, susceptibility was assumed as an element between two points (two masses)—most often susceptibility is assumed as a Voigt model (parallel combination of stiffness and damping). The tests were carried out for two configurations of train passage through a railway turnout on straight and diverging track. The track stiffness parameters of the railway turnout were determined from deflection measurements measured by sensors positioned at different points of the turnout. The components of the railway turnout were loaded with different forces. The damping parameter was determined from bench measurements of the actual track component. The function describing this damping is dry friction and such a function was determined. The second part of the study was concerned with measurements of stiffness and moments of inertia in a railway switchyard. The analysis carried out indicated the significance of the adverse effects of selected factors on the operation of the railway track (e.g., increasing the length of non-contact of the track with the ground or additional deflections of the railway track rail arising). The paper points out that such imperfections, in addition to the calculated additional deflections, cause, among other things, disturbances in the progressive movement of the rolling stock.

Studies on high voltage dc cable connection to supply the acceleration grids of the Neutral Beam Injector for DTT

The Divertor Tokamak Test facility (DTT) is the new tokamak under construction in Frascati (Italy), with the main aim of testing different divertor magnetic configurations and technologies in view of DEMO. The Heating and Current Drive function will be provided also by one Neutral Beam Injector (NBI), accelerating negative Deuterium ions with an energy of 510 keV, giving an output power of 10 MW maximum. The Acceleration Grid Power Supply (AGPS), with 3 stages rated 167 kV each, will feed the NBI accelerator. For optical reasons, the insulating gap among the acceleration grids is at the limit of the voltage holding in vacuum, therefore frequent arc breakdowns (BD) among the grids will occur, requiring the quick switch-off of the AGPS to limit the arc energy. For the AGPS, beside the ITER-like scheme including gas-insulated HV components, an innovative approach based on the Modular Multilevel Converter (MMC) technology is being considered. This would include air-insulated HV converters, requiring a huge building volume, which at present is not available in close proximity to the tokamak building. The alternative of installing the MMC converters in a new building to be erected in an available area located far from the tokamak, and connecting the AGPS to the load with HV coaxial cables, is under study. This paper presents the studies carried out to verify the impact of the cables length on the arc energy, in case of breakdown among the grids, and to estimate the magnitude of the voltage oscillations due to resonance effects. These oscillations can occur not only between each hot pole and the return conductor, endangering the cable insulation, but also between the return conductor and local ground, with potential consequences on the laying method, the human safety and the electromagnetic compatibility with sensitive apparatus nearby, which have all been evaluated.

Recent and Past Arboreal Change: Observational and Retrospective Studies Within a Subalpine, Birch-Dominated (Betula Pubescens Ssp. Czerepanovii) Mountain Valley in the Southern Swedish Scandes-Responses to Climate Change and Land Use

Multi-scale observations and reconstructions of treeline and associated plant cover changes are reviewed in this study. The main focus is on the dynamics of the treeline ecotone within a mountain valley in the southern Swedish Scandes. This area is well-researched for more than 100 years, with a background of historical studies covering the entire Holocene epoch. Trees were present on ice-free nunataks already during the Late-Glacial, 17 000-13 000 cal. a BP. Mountain birch (Betula pubescens ssp. czerepanovii), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) then grew 400-700 m higher than their current treelines, indicative of summer temperatures 3 °C higher than present. In addition, the tree flora contained Siberian larch (Larix sibirica) and broad-leaf thermophilic and deciduous species, Quercus robur, Corylus avellana, Ulmus glabra and Alnus glutinosa. Eventually, the climate turned cooler, particularly enhanced around 5000 cal. a BP. This course of change initiated the Neoglacial period, when thermophilic species were extirpated. Concomitantly, mountain birch forest and spruce benefitted from this course of change. Pine, on the other hand was disfavored and regressed in the treeline elevation and general abundance on the landscape. These trends continued until the Mediaeval period AD 1000-1300, when temperature raised above present-day standards and the pine treeline locally shifted upslope by at least 100 m. This favourable epoch was discontinued quite abruptly by resurgence of Neoglacial cooling; the “Little Ice Age”, which prevailed until the late 19th century. Widespread glacier expansion, high-elevation arboreal decline and treeline retraction then occurred. With a gentle onset in the late 19th century or somewhat earlier, a modern and still prevailing warming period was accentuated by the late 1930s. Subsequently, slight cooling prevailed for 3-4 decades, whereupon warming was resumed with short interruptions until the present day. One distinct short-term cooling-conditioned setback occurred during the 1980s. Transient permafrost formed close to the treeline, and locally some treeline recession took place. Thereafter, warming has re-occurred and glaciers and permafrost have receded. Treeline rise and densification of the treeline ecotone are once again active processes in the mountainscape. Currently, most conspicuous is a process of pine reclamation of local ground lost during the Little Ice Age. Hereabouts, seed regeneration, still virtually without winter injuries, is taking place at an unprecedented rate and abundance. Mountain birch is gaining ground in snow rich depressions in the birch belt and is currently regressing in exposed and snow-poor sections of the local topography. Current biotic changes within the treeline ecotone are well within the ranges of inferred natural variabilty during the postglacial period.

Calabar Carnival

Calabar Carnival

System response of an interlayered deposit with a localized graben deformation in the Northridge earthquake

The Wynne Avenue site in the California San Fernando Valley was analyzed using two-dimensional (2D) nonlinear dynamic analyses (NDAs) with geostatistical subsurface modeling to interpret key mechanisms contributing to a 12-m-wide graben deformation with vertical offsets of 10–20 cm in the 1994 Northridge earthquake. In-situ data from borings and cone penetration tests (CPTs), joined with geological interpretations of the distal alluvial fan deposition, delineate interlayered silty sand lenses within a typically fine-grained soil stratigraphy. The NDAs used the PM4Sand and PM4Silt constitutive models with the FLAC finite difference program. NDAs with uniform properties for distinct soil zones closely reproduced the observed graben. However, stochastic NDAs, modeled with sequential Gaussian simulations (SGS) for conditional random field realizations of critical zones, often obscured the expected graben. The ability of the stochastic NDAs to model the graben was further reduced when SGS was performed collectively over two distinct soil zones. The NDAs provide new insights on the causal mechanisms of liquefaction-induced ground oscillations and lurching, that were not easily deduced from common one-dimensional (1D) liquefaction vulnerability indices (LVIs) and Newmark sliding-block analyses. This case study demonstrates the capabilities of system-level NDAs for modeling localized ground deformation patterns, but also highlights cautionary nuances for their implementation with data-driven stochastic subsurface modeling.

Ising spin glass on random graphs at zero temperature: Not all spins are glassy in the glassy phase

We investigate the replica symmetry broken (RSB) phase of spin glass (SG) models in a random field defined on Bethe lattices at zero temperature. From the properties of the RSB solution we deduce a closed equation for the extreme values of the cavity fields. This equation turns out not to depend on the parameters defining the RSB, and it predicts that the spontaneous RSB does not take place homogeneously on the whole system. Indeed, there exist spins having the same effective local field in all local ground states, exactly as in the replica symmetric (RS) phase, while the spontaneous RSB manifests only on the remaining spins, whose fraction vanishes at criticality. The characterization in terms of spins having fixed or fluctuating local fields can be extended also to the random field Ising model (RFIM), in which case the fluctuating spins are the only responsible for the spontaneous magnetization in the ferromagnetic phase. Close to criticality we are able to connect the statistics of the local fields acting on the spins in the RSB phase with the correlation functions measured in the paramagnetic phase. Identifying the two types of spins on given instances of SG and RFIM, we show that they participate very differently to avalanches produced by flipping a single spin. From the scaling of the number of spins inducing RSB effects close to the critical point and using the $M$-layer expansion we estimate the upper critical dimension $D_U \geq 8$ for SG.

A thermal origin for super-high-frequency marsquakes

Of the marsquakes detected, super-high-frequency marsquakes are dominant (>60%) in number. However, their occurrence mechanism remains unclear. One possibility is local heat-induced ground motion. We model heat conduction under InSight based on measured subsurface thermal parameters and air temperature records, which provide insights into heat flow in the shallow Martian subsurface. Diurnal and seasonal variations of subsurface temperature and their rates of temperature change are analyzed. Diurnal temperature variations >1 K only occur within 25 cm of the surface. The highest rate of temperature change appears around sol 440 (in summer), which coincides closely with the season of the dominant number of super-high-frequency marsquakes observed. Thermal-mechanical finite-element simulations indicate that heat-induced ground motion is evidently stronger in the daytime than at night. These results indicate that super-high-frequency marsquakes are most likely induced by thermal stress in shallow rocks on the surface or partially buried within 10 cm depth.

Forecasting changes of the magnetic field in the United Kingdom from L1 Lagrange solar wind measurements

Extreme space weather events can have large impacts on ground-based infrastructure important to technology-based societies. Machine learning techniques based on interplanetary observations have proven successful as a tool for forecasting global geomagnetic indices, however, few studies have examined local ground magnetic field perturbations. Nowcast and forecast models which predict the magnitude of the horizontal geomagnetic field, |BH|, and its time derivative, dBHdt, at ground level would be valuable for assessing the potential space weather hazard. We attempt to predict the variation of the magnetic field at the three United Kingdom observatories (Eskdalemuir, Hartland and Lerwick) driven by L1 solar wind parameters. The horizontal magnetic field component and its time derivative are predicted from solar wind plasma and interplanetary magnetic field observations using Long Short-Term Memory (LSTM) networks and hybrid Convolutional Neural Network-LSTM models. A 5-fold grid search cross-validation is used for tuning the hyperparameters in each model. Forecasts were made with 5, 15 and 30-min lead times. Models were trained and validated with geomagnetic storm-only data from 1997 to 2016; their outputs were evaluated with the 7–9th September 2017 storms. The forecast models are only able to predict the directly driven parts of geomagnetic storms (not the substorms) and LSTM models generally perform best. We find the |BH| 15- and 30-min forecasts at Lerwick and Eskdalemuir have some predictive power. The 5-min |BH| forecast as well as all the dBHdt models for Eskdalemuir and all the Hartland models were found to have little or no predictive power. This suggests that the machine learning models have better forecasting power at higher latitude (closer to the auroral zones), where the ground magnetic variation field is larger and during storm onset, which is directly driven by changes in the solar wind.

Sonic boom measurements: Practical implications considering ground effects, microphone installation, and weather hardening.

Sonic boom measurements from recent flight tests have provided an opportunity to investigate effects of microphone installation on sonic boom waveforms, spectra, and metric levels in support of NASA X-59 flight test planning. While those flight tests used N-wave aircraft (F-18s), modeling studies were also conducted using source characteristics for a shaped low-boom aircraft. Of particular interest were the effects of receiver height on boom waveforms and metrics at elevated receiver positions, microphone installation, and local ground cover type. Reductions of more than 2 dB in A-weighted sound exposure level and perceived level were shown for 1.6 ft (0.48 m) microphone heights for 35º ray elevation angle. Measured and modeled results are described in this letter.

Earthquake Risk Assessment of Sabah, Malaysia Based on Geospatial Approach

Sabah is located in the northeast region of East Malaysia and recognized as the most active seismic area in Malaysia. The scalability and frequency of earthquakes are growing due to the existence of both local and distant ground motions from active faults, with more than 67 earthquake occurrences with light to moderate magnitude (Mw larger than 3.5)recorded since the 1900. On the other hand, the skewed socio-economic development process associated with the rapid population growth and changes in the family structure, inequality issues, and the lack of adaptation measures would intensify the vulnerability of the earthquakes. Key elements linked to socio-economic vulnerability need to be addressed in order to reduce the risk of earthquake. Based on previous studies, we identified vulnerabilities from a multi-dimensional perspective consisting of exposure, resilience and capacity across districts. Subsequently, a holistic indicator system with 18 variables was constructed to assess the potential earthquake vulnerability in Sabah, Malaysia. The accumulated data will present an earthquake vulnerability classification using the Geographical Information System (GIS) approach. Finally, the earthquake risk was derived by integrating the earthquake vulnerability map with earthquake hazard map proposed by the Department of Mineral and Geoscience (JMG) Malaysia. The results of the analysis revealed that the highest level of earthquake risk, which accounts for 15.5 %, were concentrated in the eastern part of the Sabah region; the high-risk areas account for 7.7 %; the moderate-risk areas account for 11.3 %; and the low to very low risk areas account for 65.4 %. Accordingly, it is expected that the derived earthquake vulnerability and risk map will allow the policymakers and response teams to improve the earthquake disaster mitigation and management in Sabah.

Back-analyses of co-seismic landslides in carbonate fault rocks due to the Mw 6.5 earthquake (2015) in Lefkada island, Greece

During the Mw 6.5 earthquake (2015) in Lefkada Ιsland, Greece, nearly 700 co-seismic landslides occurred along the western coastline of the island, where carbonate fault rocks, primarily fractured limestones and fault breccias, are encountered on steep slopes. The main objective of the present study is the investigation of a selected number of these landslides considering the local topography, ground conditions and seismicity of the area. The main challenge is the limitations due to the accessibility of the slopes and the difficulty of sampling and laboratory testing the carbonate fault rocks. For this reason, back-analysis of the failures is the only method for the determination of the upper limit of shear strength of the materials comprising the slopes. Remote sensing techniques were used for mapping the investigated landslides, since their locations were not accessible, especially after the occurrence of the landslide events. Three-dimensional models (Point Clouds) were created and used to define the geometric characteristics of eleven (11) major landslides that were back-analyzed using the limit equilibrium method (LEM). The findings of the present study indicate that the studied materials are very weak, having a Uniaxial Compressive Strength (UCS) which approximates the lower strength threshold (0.25 MPa) of weak rocks as defined by ISRM (1981). This can be attributed to the intense tectonic disturbance that these limestones have undergone in the past. Moreover, further LEM analyses were conducted for neighboring slope surfaces that did not fail during the same earthquake and proved that the mechanical properties of the ground improve with depth, a fact that can be associated with more intense weathering and relaxation near the ground surface.

Urine metabolomics analysis of sleep quality in deep-underground miners: A pilot study.

BackgroundIn previous questionnaire surveys of miners, sleep disorders were found among underground workers. The influence of the special deep-underground environment and its potential mechanism are still unclear. Therefore, this study intends to utilize LC-MS metabolomics to study the potential differences between different environments and different sleep qualities.MethodsTwenty-seven miners working at 645–1,500 m deep wells were investigated in this study, and 12 local ground volunteers were recruited as the control group. The Pittsburgh Sleep Quality Index (PSQI) was used to examine and evaluate the sleep status of the subjects in the past month, and valuable basic information about the participants was collected. PSQI scores were obtained according to specific calculation rules, and the corresponding sleep grouping and subsequent analysis were carried out. Through liquid chromatography-mass spectrometry (LC-MS) non-targeted metabolomics analysis, differences in metabolism were found by bioinformatics analysis in different environments.ResultsBetween the deep-underground and ground (DUvsG) group, 316 differential metabolites were identified and 125 differential metabolites were identified in the good sleep quality vs. poor sleep quality (GSQvsPSQ) group. The metabolic pathways of Phenylalanine, tyrosine and tryptophan biosynthesis (p = 0.0102) and D-Glutamine and D-glutamate metabolism (p = 0.0241) were significantly enriched in DUvsG. For GSQvsPSQ group, Butanoate metabolism was statistically significant (p = 0.0276). L-Phenylalanine, L-Tyrosine and L-Glutamine were highly expressed in the deep-underground group. Acetoacetic acid was poorly expressed, and 2-hydroxyglutaric acid was highly expressed in good sleep quality.ConclusionsThe influence of the underground environment on the human body is more likely to induce specific amino acid metabolism processes, and regulate the sleep-wake state by promoting the production of excitatory neurotransmitters. The difference in sleep quality may be related to the enhancement of glycolytic metabolism, the increase in excitatory neurotransmitters and the activation of proinflammation. L-phenylalanine, L-tyrosine and L-glutamine, Acetoacetic acid and 2-hydroxyglutaric acid may be potential biomarkers correspondingly.