4,801 research outputs found

    Glaciochemical records from the Saint Elias Mountains, Yukon, Canada

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    While many paleoclimate records have been recovered from the North Atlantic sector of the Arctic, there is a gap in our understanding of climactic and environmental change in the North Pacific. Glaciochemical records from the St. Elias Mountains spanning an elevation range of three to five km provide a three-dimensional view of the paleo-atmosphere in this region. Three ice cores from Eclipse Icefield provide a high-resolution record of precipitation chemistry in the remote northwestern North America mid-troposphere and allow investigation of spatial and temporal variability in glaciochemical signals. Greater spatial variability is observed for species present as coarse mode dust and sea salt particles than for accumulation mode sulfate and ammonium aerosols or gas phase nitrate. Simultaneous sampling of aerosol and snow chemistry at King Col indicates large enrichments of nitrate and chloride in snow relative to aerosol by scavenging of gas phase nitric and hydrochloric acid. Back trajectories document the transport of Asian dust and anthropogenic emissions, the May 22 eruption plume of Sheveluch, Kamchatka, and sea salt from the Gulf of Alaska to King Col during the sampling period. The Eclipse ice cores provide a record of forest fire activity in Alaska and the Yukon that responds to anthropogenic influences such as the Klondike Gold Rush and natural climate variability such as the Medieval Warm Period. The Eclipse and Mt. Logan ice cores offer a record of regionally significant volcanic eruptions, with at least one-third of the eruptions recorded from Alaskan and Kamchatkan volcanoes. Major tropical eruptions are also recorded. The three Eclipse cores record similar volcanic sulfate fluxes from the largest eruptions such as Katmai, as well as some moderate eruptions. While a bipolar volcanic signal in 1809 is generally attributed to single tropical eruption, dacitic tephra from the Eclipse ice core that is chemically distinct from andesitic 1809 tephra found in Antarctica indicates a second eruption in the Northern Hemisphere at this time. Sulfate flux calculations suggest this eruption contributed little additional sulfate to circum-Arctic ice cores, and therefore had negligible climatic significance

    Distribution of some elements in Veronica scutellata L. from Bolu,Turkey: soil-plant interactions

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    Veronica scutellata L. occurs in moist and wet habitats, such as ponds, marshes and other wetlands. This study was conducted on this species to examine its mineral element uptake status in terms of interactions between soil and plant. Experimental materials were taken from the Southern coast of Black Sea at coordinates 40º36’N and 31º16’E at an altitude of 1400 m above sea level from Bolu – Turkey; using standard methods and plant (root, stem and leaf parts) and soil mineral element measurements (Al, B, Ca, Cu, Fe, K, Mg, Mn, Na, Ni and Zn) were done. During the study, ICP-OES was employed for the measurement of mineral elements. It was observed that considerable amounts of B, Ca, K, Mg, Mn, Na and Zn are accumulated by the plant

    Internet access for disabled people: Understanding socio-relational factors in Europe

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    Access to the Internet has become a sine qua non-of everyday life. It also offers new routes to economic and social inclusion for disabled people. Research on the digital divide shows that social factors affect Internet access but disability status is often overlooked. This paper assesses the extent to which disability makes a difference and how it interacts with other social effects to produce distinctive forms of digital exclusion. The analysis uses survey data from 27 European countries to explore and model, statistically, the interactions between Internet access, disability status, age, gender, education, household financial situation and household composition. Multilevel analysis confirms that socio-demographic factors can explain much variance in outcomes but there is a distinctive disability effect. In particular, the adverse effects of financial constraint, aging and living alone are exacerbated among disabled people. New policies to strengthen e-accessibility, arising from the United Nations Convention on the Rights of Persons with Disabilities and from the European Union, are important but cannot ignore those who are still excluded from the online revolution. Disabled people are over-represented in this group. The evidence suggests that both accessible technologies and appropriate supportive relationships are needed to address this

    Preliminary assessment of microfibres amount in textile wastewater

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    Textile wastewater is a complex mixture of inorganic compounds, polymers, organic products, dyes, and microfibers (MFs), including microplastics (MPs) and natural fibers. The treatment of textile wastewater, which contains a significant share of MFs, is of great importance to prevent the release of MPs in the environment. MPs analysis requires multiple phases of pretreatment (to eliminate the organic compounds), separation of the MFs from the water, and identification of the MPs among the MFs.This work presents the preliminary results of a research aimed at exploring two issues. Firstly, the pretreatment (through Fenton, H2O2, HCl, KOH and NaOH, applied at 25 °C for 5 days and 60 °C for 6 hours) of artificial textile wastewater, evaluating the effect of the different conditions on the MFs and the MPs. Secondly, the separation of MFs from a real textile wastewater sample through different processes (centrifugation, sink-float & filtration, filtration). The results of the pretreatment tests revealed Fenton, HCl, and H2O2 at 25 °C for 5 days as the best performing chemicals and conditions. Considering the results of the separation tests, filtration gave back the best removal of the MFs from wastewater compared to centrifugation and sink-float and filtration, which left some MFs in the supernatant/float and in the sediment/sink. In conclusion, these preliminary results may be useful to further explore the detection of MFs and MPs in textile wastewater

    Constraining recent lead pollution sources in the North Pacific using ice core stable lead isotopes

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    Trends and sources of lead (Pb) aerosol pollution in the North Pacific rim of North America from 1850 to 2001 are investigated using a high-resolution (subannual to annual) ice core record recovered from Eclipse Icefield (3017 masl; St. Elias Mountains, Canada). Beginning in the early 1940s, increasing Pb concentration at Eclipse Icefield occurs coevally with anthropogenic Pb deposition in central Greenland, suggesting that North American Pb pollution may have been in part or wholly responsible in both regions. Isotopic ratios (208Pb/207Pb and 206Pb/207Pb) from 1970 to 2001 confirm that a portion of the Pb deposited at Eclipse Icefield is anthropogenic, and that it represents a variable mixture of East Asian (Chinese and Japanese) emissions transported eastward across the Pacific Ocean and a North American component resulting from transient meridional atmospheric flow. Based on comparison with source material Pb isotope ratios, Chinese and North American coal combustion have likely been the primary sources of Eclipse Icefield Pb over the 1970–2001 time period. The Eclipse Icefield Pb isotope composition also implies that the North Pacific mid-troposphere is not directly impacted by transpolar atmospheric flow from Europe. Annually averaged Pb concentrations in the Eclipse Icefield ice core record show no long-term trend during 1970–2001; however, increasing 208Pb/207Pb and decreasing 206Pb/207Pb ratios reflect the progressive East Asian industrialization and increase in Asian pollutant outflow. The post-1970 decrease in North American Pb emissions is likely necessary to explain the Eclipse Icefield Pb concentration time series. When compared with low (lichen) and high (Mt. Logan ice core) elevation Pb data, the Eclipse ice core record suggests a gradual increase in pollutant deposition and stronger trans-Pacific Asian contribution with rising elevation in the mountains of the North Pacific rim

    Fouling and boring organisms that deteriorate various European and tropical woods at Turkish seas

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    This study aims to investigate the diversity of fouling and boring organisms damaging wood material at Turkish coasts. Trials were carried out at six harbour sites throughout the seas surrounding Turkey.Various Euopean and tropical wood samples were hanged down at a depth of six meters in the sea for a period of one year. Identification of the organisms obtained from wood panels revealed the presence offive wood borer and 26 fouling species. skenderun harbour had the highest boring organism diversity (five species) and it was followed by Trabzon and Finike harbours (three species) and Bandirma, Eregli and Alacati harbours (two species). The two molluscan boring species, Teredo navalis and Lyrodus pedicellatus were observed at all harbour sites, but Nototeredo norvegica was at Trabzon and skenderun harbours only. Bankia carinata was obtained only at skenderun harbour and the crustacean wood borer Limnoria tripunctata was found at Finike and skenderun harbours. All native tree species, except for the olive, were significantly damaged by fouling and boring organisms

    Characterization of disturbed hemodynamics due to stenosed aortic jets with a Lagrangian Coherent structures technique

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    Isfahan University of Technology. The aortic valve is located at left ventricular outlet and is exposed to the highest pressure in the cardiovascular system. Problems associated with the valve leaflet movement can cause complications for the heart. Specifically, aortic stenosis (AS) arises when aortic leaflets do not efficiently open. In the present study, Lagrangian Coherent Structures (LCSs) were utilized by processing a variety of Computational Fluid Dynamics (CFD) models velocity vector data further to identify the characteristics of AS jets. Particularly, effective orifice areas (EOA) for different cases were accurately identified from unstable manifolds of finite time Lyapunov exponent (FTLE) fields. Calcified leaflets were modeled by setting the leaflet's Young modulus to 10 MPa and 20 MPa for moderately and severely calcified leaflets respectively while a healthy leaflet's Young modulus was assigned to be 2 MPa. Increase in calcification degree of the leaflet caused destruction of the vortex structures near the fibrosa layer of the leaflet indicating a malfunctioning for the movement mechanism of the leaflet. Furthermore, when we analyzed stable manifolds, we identified a blockage region at the flow upstream due to the stagnant blood here. Compared to a healthy case, for the calcified valve, this blockage region was enlarged, implying an increase in AS jet velocity and wall shear stress on leaflets. As a conclusion, results from the present study indicate that aortic leaflet malfunctioning could be accurately evaluated when LCS technique was employed by post processing velocity vector data from CFD. Such precise analysis is not possible using the Eulerian CFD approach or a Doppler echocardiography since these methods are based on only analyzing instantaneous flow quantities and they overlook fluid flow characteristics of highly unsteady flows

    Bisphenol A sulfonation is impaired in metabolic and liver disease

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    Background: Bisphenol A (BPA) is a widely used industrial chemical and suspected endocrine disruptor to which humans are ubiquitously exposed. The liver metabolizes and facilitates BPA excretion through glucuronidation and sulfonation. The sulfotransferase enzymes contributing to BPA sulfonation (detected in human and rodents) is poorly understood. Objectives: To determine the impact of metabolic and liver disease on BPA sulfonation in human and mouse livers. Methods: The capacity for BPA sulfonation was determined in human liver samples that were categorized into different stages of metabolic and liver disease (including obesity, diabetes, steatosis, and cirrhosis) and in livers from ob/ob mice. Results: In human liver tissues, BPA sulfonation was substantially lower in livers from subjects with steatosis (23%), diabetes cirrhosis (16%), and cirrhosis (18%), relative to healthy individuals with non-fatty livers (100%). In livers of obese mice (ob/ob), BPA sulfonation was lower (23%) than in livers from lean wild-type controls (100%). In addition to BPA sulfonation activity, Sult1a1 protein expression decreased by 97% in obese mouse livers. Conclusion: Taken together these findings establish a profoundly reduced capacity of BPA elimination via sulfonation in obese or diabetic individuals and in those with fatty or cirrhotic livers versus individuals with healthy livers

    Kikuchi — Fujimoto disease: cervical lymphadenopathy suggestive of relapsing lymphoma in patient with lymphoblastic lymphoma

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    Aim: Kikuchi — Fujimoto disease (KFD) or histiocytic necrotizing lymphadenitis is a rare disorder and often confused with lymphoma. Patient: There is presented a case of 28-year-old patient with cervical lymphadenopathy, who had history of lymphoma. Results: On immunohistopathologic examination diagnosis of KFD was made and patient followed without any treatment. Conclusion: Patient’s lymphadenopathy had almost resolved and he was completely asymptomatic after three months. In patient with cervical lymphadenopathy KFD should be considered in the differential diagnosis
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