237 research outputs found
The Relationship between Lead in Groundwater and Elementary School Students\u27 Academic Performance in Missouri
Lead exposure can come from various sources, e.g., lead mines, industrial areas, and lead based paint. Missouri has more than 4,128 lead mines. Lead is a neurotoxin. The objectives of the study were to investigate i) the spatial relationship between lead mines and lead distribution in groundwater, ii) the statistical impact of lead in groundwater on students\u27 Missouri Assessment Program (MAP) scores, and iii) the geographic variations of lead\u27s impact on students\u27 MAP scores. Geographic Information Science spatial analysis tools were used to analyze the concentration of lead in groundwater within school districts in Missouri. Regression analysis was utilized to study the effect of neighborhood lead concentration in groundwater on students\u27 MAP scores. Geographically weighted regression (GWR) analysis results show the geographic variations of lead\u27s impact on students\u27 MAP scores across different areas in Missouri from significant to insignificant. The results of this study show no relationships between lead mines density and lead level distribution in groundwater. In localized areas, it shows the geographical variability of the spatial relationship between lead in groundwater and MAP scores. This study provides better understanding of the relationship between environmental factors and elementary students\u27 academic performance
Influence of mainland China’s industrial structure evolution on the development of Cross-Strait trade: the grey relational analysis (2011–2020)
Because of the complex and special political relationship between
Mainland China and Taiwan. Cross-Strait trade is influenced by
many variables, there has been a view that trade relations
between Mainland China and Taiwan are more influenced by political
factors. However, between the Cross-Strait, the trade volume
has generally shown an upward development trend, especially
since 2001. Therefore, the political factors can hardly explain the
facts, and economic factors, especially industrial structure factors
in Mainland China play an important role in Cross-Strait trade.
Based on the small sample data since 2001, this study employed
Grey Relational Analysis (GRA) method to verify the evolution
of Mainland China’s industrial structure and Cross-Strait trade.
Based on the results show that the evolution of Mainland China’s
industrial structure strongly impacts the development of Cross-
Strait trade. The tertiary industry has the strongest correlation
with Cross-Strait trade, followed by the secondary and primary
industries. Furthermore, the evolution of the mainland’s industrial
structure will expand as well as accelerate the imbalance of
Cross-Strait trade
Maritime coverage enhancement using UAVs coordinated with hybrid satellite-terrestrial networks
Due to the agile maneuverability, unmanned aerial vehicles (UAVs) have shown great promise for on-demand communications. In practice, UAV-aided aerial base stations are not separate. Instead, they rely on existing satellites/terrestrial systems for spectrum sharing and efficient backhaul. In this case, how to coordinate satellites, UAVs and terrestrial systems is still an open issue. In this paper, we deploy UAVs for coverage enhancement of a hybrid satellite-terrestrial maritime communication network. Using a typical composite channel model including both large-scale and small-scale fading, the UAV trajectory and in-flight transmit power are jointly optimized, subject to constraints on UAV kinematics, tolerable interference, backhaul, and the total energy of the UAV for communications. Different from existing studies, only the location-dependent large-scale channel state information (CSI) is assumed available, because it is difficult to obtain the small-scale CSI before takeoff in practice and the ship positions can be obtained via the dedicated maritime Automatic Identification System. The optimization problem is non-convex. We solve it by using problem decomposition, successive convex optimization and bisection searching tools. Simulation results demonstrate that the UAV fits well with existing satellite and terrestrial systems, using the proposed optimization framework
Studying the thermal conductivity of a deep Eocene clay formation: direct measurements vs back-analysis results
An experimental study on Ypresian clays–one of the potential deep and sedimentary clay formations in Belgium for the geological disposal of heat-emitting radioactive waste–has been undertaken to systematically study its thermal conductivity using different experimental techniques. As a first step, a new experimental setup with heat flux measurement has been used and careful pre-conditioning protocols have been followed to directly measure this thermal property. The aim of these pre-conditioning tests has been ensuring a very high degree of saturation and the closure of fissures / gaps along bedding planes before the thermal tests are run under low stress conditions. Thermal tests have shown to be particularly sensitive when the thermal conductivity is determined along a direction orthogonal to these bedding planes. The study is then complemented by using a constant volume heating cell, in which heating pulse tests have been carried out under fully saturated conditions that have been ensured with a high water back-pressure. Numerical models have been used to interpret this pulse test, to exploit all the information provided by temperature measurements and to back-analyse the thermal conductivity. Direct thermal conductivity data with the improved pre-conditioning protocol allowed obtaining results consistent with the values reported when using back-analysis in the constant volume cell. The article discusses the importance of restoring full saturation conditions, particularly on retrieval of deep sedimentary clays, which may undergo opening of fissures along bedding planes that may affect the correct determination of the thermal conductivity.Peer ReviewedPostprint (author's final draft
WNT5A Signaling Contributes to Aβ-Induced Neuroinflammation and Neurotoxicity
Neurodegenration is a pathological hallmark of Alzheimer's disease (AD), but the underlying molecular mechanism remains elusive. Here, we present evidence that reveals a crucial role of Wnt5a signaling in this process. We showed that Wnt5a and its receptor Frizzled-5 (Fz5) were up-regulated in the AD mouse brain, and that beta-amyloid peptide (Aβ), a major constituent of amyloid plaques, stimulated Wnt5a and Fz5 expression in primary cortical cultures; these observations indicate that Wnt5a signaling could be aberrantly activated during AD pathogenesis. In support of such a possibility, we observed that inhibition of Wnt5a signaling attenuated while activation of Wnt5a signaling enhanced Aβ-evoked neurotoxicity, suggesting a role of Wnt5a signaling in AD-related neurodegeneration. Furthermore, we also demonstrated that Aβ-induced neurotoxicity depends on inflammatory processes, and that activation of Wnt5a signaling elicited the expression of proinflammatory cytokines IL-1β and TNF-α whereas inhibition of Wnt5a signaling attenuated the Aβ-induced expression of the cytokines in cortical cultures. Our findings collectively suggest that aberrantly up-regulated Wnt5a signaling is a crucial pathological step that contributes to AD-related neurodegeneration by regulating neuroinflammation
Enabling 5G on the Ocean: A Hybrid Satellite-UAV-Terrestrial Network Solution
Current fifth generation (5G) cellular networks mainly focus on the
terrestrial scenario. Due to the difficulty of deploying communications
infrastructure on the ocean, the performance of existing maritime communication
networks (MCNs) is far behind 5G. This problem can be solved by using unmanned
aerial vehicles (UAVs) as agile aerial platforms to enable on-demand maritime
coverage, as a supplement to marine satellites and shore-based terrestrial
based stations (TBSs). In this paper, we study the integration of UAVs with
existing MCNs, and investigate the potential gains of hybrid
satellite-UAV-terrestrial networks for maritime coverage. Unlike the
terrestrial scenario, vessels on the ocean keep to sea lanes and are sparsely
distributed. This provides new opportunities to ease the scheduling of UAVs.
Also, new challenges arise due to the more complicated maritime prorogation
environment, as well as the mutual interference between UAVs and existing
satellites/TBSs. We discuss these issues and show possible solutions
considering practical constraints
Detection of the four major human herpesviruses simultaneously in whole blood and cerebrospinal fluid samples by the fluorescence polarization assay
SummaryObjectivesHerpes simplex virus type 1/2 (HSV-1/-2), cytomegalovirus (CMV), and Epstein–Barr virus (EBV) correlate strongly with infections of the central nervous system. The objective of this study was to develop a method for the simultaneous detection of HSV-1/-2, CMV, and EBV DNA by the fluorescence polarization assay based on asymmetric polymerase chain reaction (PCR) and hybridization.MethodsDNA of HSV-1/-2, CMV, and EBV was amplified in an asymmetric PCR by a universal primer system. The amplicons were then detected by the fluorescence polarization assay. In this method, the probes for HSV-1/-2, CMV, and EBV hybridized with their respective target amplicons, and the hybridization resulted in an increase in the fluorescence polarization values. Infections of HSV-1/-2, CMV, and EBV were determined by the increased fluorescence polarization values. The DNA extracted from whole blood and cerebrospinal fluid samples was subjected to fluorescence polarization and a previously published multiplex PCR assay in parallel.ResultsCompared to the multiplex PCR assay, no significant difference in the numbers of samples positive for the human herpesviruses was identified by the fluorescence polarization assay.ConclusionsThe fluorescence polarization assay presented in this study is a reliable, convenient, and cost-effective diagnostic tool that allows the detection of the four major human herpesviruses
Anisotropic features on the thermal conductivity of a deep argillaceous formation
An experimental study on Ypresian clays – one of the potential deep and sedimentary clay formations in Belgium for the geological disposal of heat-emitting radioactive waste – has been undertaken to systematically study anisotropic features on the thermal conductivity using a setup with thermal flux measurement. A careful pre-conditioning protocol before the thermal tests has been followed to ensure a very high degree of saturation and the closure of fissures/gaps along bedding planes. Thermal conductivity data with this improved pre-conditioning protocol allowed obtaining results consistent with the values reported when using back-analysis in a constant volume cell with fully saturated material.Postprint (published version
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