534 research outputs found
Land use Effects on Ground Water Quality in Carbonate Rock Terrain
A control site with a natural setting and an experimental site with significant agriculture land use were studied in the Ozark Region of Arkansas in order to determine the effect of land use on water quality in a carbonate rock terrain. The vast majority of the two sites have the Boone Limestone exposed which combined with the underlying St. Joe is the major aquifer for drinking water in the area. The sites also are similar in terms of lineament patterns (number, length and orientation), soil, slope and vegetation. Ground water samples were collected primarily from springs during three seasons (late summer-early fall, winter and spring). All three seasonal collections exhibited statistically higher NO3 (2.31 versus 0.81 mg/L) and Cl (9.9 versus 2.7 mg/L) concentrations in the experimental site. During the winter and spring collections, the experimental site also exhibited statistically higher concentrations (0.5 to 3x) of PO4, SO4, Na, K and Ca. Heavy metals were analyzed in the winter samples; however, the differences between the two sites were small because the absolute values for the two sites were low. For example, the largest difference for a heavy metal was 19 μg/L for Mn (12 versus 31 μg/L). Bacteria determined from the spring season samples showed that the experimental site had significantly higher counts of fecal coliform (86 versus 0.4 col - onies/100 mL) and fecal Streptococcus (39 versus 3 colonies/100 mL) types than the control site. Three springs were also sampled periodically following a rain event of 10 cm. Whereas, levels of specific conductance, NO3, Ca and Na decreased in all three springs, PO4, K, SO4 and fecal coliform increased significantly, primarily in the two experimental springs. The increase of these parameters indicates that they are more available in the experimental area. Based on these results and elemental correlations, it appears that cattle manure, the spreading of chicken manure and commercial fertilizers, and septic tank effluent, individually or in combination, are affecting the water quality of the experimental site. However, most of the ground water samples meet EPA drinking water standards with the possible exception of bacteria
Metabolism of ticagrelor in patients with acute coronary syndromes.
© The Author(s) 2018Ticagrelor is a state-of-the-art antiplatelet agent used for the treatment of patients with acute coronary syndromes (ACS). Unlike remaining oral P2Y12 receptor inhibitors ticagrelor does not require metabolic activation to exert its antiplatelet action. Still, ticagrelor is extensively metabolized by hepatic CYP3A enzymes, and AR-C124910XX is its only active metabolite. A post hoc analysis of patient-level (n = 117) pharmacokinetic data pooled from two prospective studies was performed to identify clinical characteristics affecting the degree of AR-C124910XX formation during the first six hours after 180 mg ticagrelor loading dose in the setting of ACS. Both linear and multiple regression analyses indicated that ACS patients presenting with ST-elevation myocardial infarction or suffering from diabetes mellitus are more likely to have decreased rate of ticagrelor metabolism during the acute phase of ACS. Administration of morphine during ACS was found to negatively influence transformation of ticagrelor into AR-C124910XX when assessed with linear regression analysis, but not with multiple regression analysis. On the other hand, smoking appears to increase the degree of ticagrelor transformation in ACS patients. Mechanisms underlying our findings and their clinical significance warrant further research.Peer reviewedFinal Published versio
An expressed sequence tag (EST) library for Drosophila serrata, a model system for sexual selection and climatic adaptation studies
The native Australian fly Drosophila serrata belongs to the highly speciose montium subgroup of the melanogaster species group. It has recently emerged as an excellent model system with which to address a number of important questions, including the evolution of traits under sexual selection and traits involved in climatic adaptation along latitudinal gradients. Understanding the molecular genetic basis of such traits has been limited by a lack of genomic resources for this species. Here, we present the first expressed sequence tag (EST) collection for D. serrata that will enable the identification of genes underlying sexually-selected phenotypes and physiological responses to environmental change and may help resolve controversial phylogenetic relationships within the montium subgroup
Extracellular citrate and metabolic adaptations of cancer cells
It is well established that cancer cells acquire energy via the Warburg effect and oxidative phosphorylation. Citrate is considered to play a crucial role in cancer metabolism by virtue of its production in the reverse Krebs cycle from glutamine. Here, we review the evidence that extracellular citrate is one of the key metabolites of the metabolic pathways present in cancer cells. We review the different mechanisms by which pathways involved in keeping redox balance respond to the need of intracellular citrate synthesis under different extracellular metabolic conditions. In this context, we further discuss the hypothesis that extracellular citrate plays a role in switching between oxidative phosphorylation and the Warburg effect while citrate uptake enhances metastatic activities and therapy resistance. We also present the possibility that organs rich in citrate such as the liver, brain and bones might form a perfect niche for the secondary tumour growth and improve survival of colonising cancer cells. Consistently, metabolic support provided by cancer-associated and senescent cells is also discussed. Finally, we highlight evidence on the role of citrate on immune cells and its potential to modulate the biological functions of pro- and anti-tumour immune cells in the tumour microenvironment. Collectively, we review intriguing evidence supporting the potential role of extracellular citrate in the regulation of the overall cancer metabolism and metastatic activity
Cylindrospermopsin is effectively degraded in water by pulsed corona-like and dielectric barrier discharges
Cylindrospermopsin (CYN) is an important cyanobacterial toxin posing a major threat to surface waters during cyanobacterial blooms. Hence, methods for cyanotoxin removal are required to confront seasonal or local incidences to sustain the safety of potable water reservoirs. Non-thermal plasmas provide the possibility for an environmentally benign treatment which can be adapted to specific concentrations and environmental conditions without the need of additional chemicals. We therefore investigated the potential of two different non-thermal plasma approaches for CYN degradation, operated either in a water mist, i.e. in air, or submerged in water. A degradation efficacy of 0.03 +/- 0.00 g kWh(-1) L-1 was found for a dielectric barrier discharge (DBD) operated in air, while a submerged pulsed corona-like discharge resulted in an efficacy of 0.24 +/- 0.02 g kWh(-1) L-1. CYN degradation followed a pseudo zeroth order or pseudo first order reaction kinetic, respectively. Treatment efficacy of the corona-like discharge submerged in water increased with pH values of the initial solution changing from 5.0 to 7.5. Notably, a pH-depending residual oxidative effect was observed for the submerged discharge, resulting in ongoing CYN degradation, even without further plasma treatment. In this case hydroxyl radicals were identified as the dominant oxidants of CYN at acidic pH values. In comparison, degradation by the DBD could be related primarily to the generation of ozone
Magnetic Properties of Monomer and Dimer Tetrahedral VOx Entities Dispersed on Amorphous Silica-based Materials: Prediction of EPR Parameters from Relativistic DFT Calculations and Broken Symmetry Approach to Exchange Couplings
Molecular structures of the isolated tetrahedral oxovanadium(IV) and bridged μ-oxo-divanadium(IV) complexes hosted by the clusters mimicking surfaces of amorphous silica-based materials were investigated using density functional theory (DFT) calculations. Principal values of the g and A tensors for the monomer vanadyl species were obtained using the coupled-perturbed DFT level of theory and the spin–orbit mean-field approximation (SOMF). Magnetic exchange interaction for the μ-oxo bridged vanadium(IV) dimer was investigated within the broken symmetry approach. An antiferromagnetic coupling of the individual magnetic moments of the vanadium(IV) centers in the [VO–O–VO]2+ bridges was revealed and discussed in detail. The coupling explains pronounced decrease of the electron paramagnetic resonance signal (EPR) intensity, observed for the reduced VOx/SiO2 samples with the increasing coverage of vanadia, in terms of transformation of the paramagnetic monomer species into the dimers with S = 0 ground state
The Pioneer Anomaly
Radio-metric Doppler tracking data received from the Pioneer 10 and 11
spacecraft from heliocentric distances of 20-70 AU has consistently indicated
the presence of a small, anomalous, blue-shifted frequency drift uniformly
changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was
interpreted as a constant sunward deceleration of each particular spacecraft at
the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of
the Newton's gravitational inverse-square law has become known as the Pioneer
anomaly; the nature of this anomaly remains unexplained. In this review, we
summarize the current knowledge of the physical properties of the anomaly and
the conditions that led to its detection and characterization. We review
various mechanisms proposed to explain the anomaly and discuss the current
state of efforts to determine its nature. A comprehensive new investigation of
the anomalous behavior of the two Pioneers has begun recently. The new efforts
rely on the much-extended set of radio-metric Doppler data for both spacecraft
in conjunction with the newly available complete record of their telemetry
files and a large archive of original project documentation. As the new study
is yet to report its findings, this review provides the necessary background
for the new results to appear in the near future. In particular, we provide a
significant amount of information on the design, operations and behavior of the
two Pioneers during their entire missions, including descriptions of various
data formats and techniques used for their navigation and radio-science data
analysis. As most of this information was recovered relatively recently, it was
not used in the previous studies of the Pioneer anomaly, but it is critical for
the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living
Reviews in Relativit
Potential range of impact of an ecological trap network: the case of timber stacks and the Rosalia longicorn
Although the negative impact of timber stacks on populations of saproxylic beetles is a well-known phenomenon, there is
relatively little data concerning the scale of this impact and its spatial aspect. Beech timber stored in the vicinity of the forest
can act as an ecological trap for the Rosalia longicorn (Rosalia alpina), so in this study we have attempted to determine the
spatial range of the impact of a network of timber stacks. Timber stacks in the species’ range in the study area were listed
and monitored during the adult emergence period in 2014–2016. Based on published data relating to the species’ dispersal
capabilities, buffers of four radii (500, 1000, 1600, 3000 m) were delineated around the stacks and the calculated ranges of
potential impact. The results show that the percentage of currently known localities of the Rosalia longicorn impacted by
stacks varies from 19.7 to 81.6%, depending on the assumed impact radius. The percentage of forest influenced by timber
stacks was 77% for the largest-radius buffer. The overall impact of the ecological trap network is accelerated by fragmentation
of the impact-free area. It was also found that forests situated close to the timber stacks where the Rosalia longicorn was
recorded were older and more homogeneous in age and species composition than those around stacks where the species was
absent. Such results suggest that timber stacks act as an ecological trap in the source area of the local population
Phenotypic variation of erythrocyte linker histone H1.c in a pheasant (Phasianus colchicus L.) population
Our goal was to characterize a phenotypic variation of the pheasant erythrocyte linker histone subtype H1.c. By using two-dimensional polyacrylamide gel electrophoresis three histone H1.c phenotypes were identified. The differently migrating allelic variants H1.c1 and H1.c2 formed either two homozygous phenotypes, c1 and c2, or a single heterozygous phenotype, c1c2. In the pheasant population screened, birds with phenotype c2 were the most common (frequency 0.761) while individuals with phenotype c1 were rare (frequency 0.043)
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