675 research outputs found
WATER QUALITY DURING TWO HIGH-FLOW YEARS ON THE LOWER MISSOURI RIVER: THE EFFECTS OF RESERVOIR AND TRIBUTARY CONTRIBUTIONS
Complex socioeconomic and ecological issues, ranging from impaired streams to Gulf of Mexico hypoxia, have made nutrient management an increasingly important issue across the USA. High flows during 2010 and 2011 provided a unique opportunity to investigate trends in discharge, total nitrogen, nitrate/nitrite, total phosphorus, orthophosphorus, suspended sediment and total suspended solids during two distinct high-flow years on the Missouri River. We compared collections taken during 2010 and 2011 at 12 lower Missouri River locations (river kilometers 1212 to 71) and 22 Missouri River tributary locations. During 2011, average concentrations for all sampled parameters were significantly lower, despite significantly higher total discharge, than 2010 concentrations. Differences in water chemistry between years are likely attributed to the primary source of water. Tributary inflow created high flows during 2010, whereas record releases from Gavinâs Point Dam created high flows during 2011. Analysis of flow estimated the contribution of these releases at each site and revealed strong positive relationships between the percentage of estimated tributary flow at each site and the concentrations of total nitrogen, total phosphorus and total suspended solids. These monitoring efforts underline the contrasting impacts that tributary streams and reservoir releases have on nutrient export of the Missouri River during high-flow events and reveal a larger trend of increased nutrient concentrations as the proportion of Missouri River tributary flow increased
Altered functional brain network connectivity and glutamate system function in transgenic mice expressing truncated Disrupted-in-Schizophrenia 1
Considerable evidence implicates DISC1 as a susceptibility gene for multiple psychiatric diseases. DISC1 has been intensively studied at the molecular, cellular and behavioral level, but its role in regulating brain connectivity and brain network function remains unknown. Here, we utilize a set of complementary approaches to assess the functional brain network abnormalities present in mice expressing a truncated Disc1 gene (Disc1tr Hemi mice). Disc1tr Hemi mice exhibited hypometabolism in the prefrontal cortex (PFC) and reticular thalamus along with a reorganization of functional brain network connectivity that included compromised hippocampalâPFC connectivity. Altered hippocampalâPFC connectivity in Disc1tr Hemi mice was confirmed by electrophysiological analysis, with Disc1tr Hemi mice showing a reduced probability of presynaptic neurotransmitter release in the monosynaptic glutamatergic hippocampal CA1âPFC projection. Glutamate system dysfunction in Disc1tr Hemi mice was further supported by the attenuated cerebral metabolic response to the NMDA receptor (NMDAR) antagonist ketamine and decreased hippocampal expression of NMDAR subunits 2A and 2B in these animals. These data show that the Disc1 truncation in Disc1tr Hemi mice induces a range of translationally relevant endophenotypes underpinned by glutamate system dysfunction and altered brain connectivity
Recent progress in biohydrometallurgy and microbial characterisation
Since the discovery of microbiological metal dissolution, numerous biohydrometallurgical approaches have been developed to use microbially assisted aqueous extractive metallurgy for the recovery of metals from ores, concentrates, and recycled or residual materials. Biohydrometallurgy has helped to alleviate the challenges related to continually declining ore grades by transforming uneconomic ore resources to reserves. Engineering techniques used for biohydrometallurgy span from above ground reactor, vat, pond, heap and dump leaching to underground in situ leaching. Traditionally biohydrometallurgy has been applied to the bioleaching of base metals and uranium from sulfides and biooxidation of sulfidic refractory gold ores and concentrates before cyanidation. More recently the interest in using bioleaching for oxide ore and waste processing, as well as extracting other commodities such as rare earth elements has been growing. Bioprospecting, adaptation, engineering and storing of microorganisms has increased the availability of suitable biocatalysts for biohydrometallurgical applications. Moreover, the advancement of microbial characterisation methods has increased the understanding of microbial communities and their capabilities in the processes. This paper reviews recent progress in biohydrometallurgy and microbial characterisatio
A control on quantum fluctuations in 2+1 dimensions
A functional method is discussed, where the quantum fluctuations of a theory
are controlled by a mass parameter and the evolution of the theory with this
parameter is connected to its renormalization. It is found, in the framework of
the gradient expansion, that the coupling constant of a N=1 Wess-Zumino theory
in 2+1 dimensions does not get quantum corrections.Comment: Comments adde
Compressed sensing reconstruction for high-SNR, rapid dissolved 129Xe gas exchange MRI
Purpose
Three-dimensional hyperpolarized 129Xe gas exchange imaging suffers from low SNR and long breath-holds, which could be improved using compressed sensing (CS). The purpose of this work was to assess whether gas exchange ratio maps are quantitatively preserved in CS-accelerated dissolved-phase 129Xe imaging and to investigate the feasibility of CS-dissolved 129Xe imaging with reduced-cost natural abundance (NA) xenon.
Methods
129Xe gas exchange imaging was performed at 1.5âT with a multi-echo spectroscopic imaging sequence. A CS reconstruction with an acceleration factor of 2 was compared retrospectively with conventional gridding reconstruction in a cohort of 16 healthy volunteers, 5 chronic obstructive pulmonary disease patients, and 23 patients who were hospitalized following COVID-19 infection. Metrics of comparison included normalized mean absolute error, mean gas exchange ratio, and red blood cell (RBC) image SNR. Dissolved 129Xe CS imaging with NA xenon was assessed in 4 healthy volunteers.
Results
CS reconstruction enabled acquisition time to be halved, and it reduced background noise. Median RBC SNR increased from 6 (2â18) to 11 (2â100) with CS, and there was strong agreement between CS and gridding mean ratio map values (R2â=â0.99). Image fidelity was maintained for gridding RBC SNR >â5, but below this, normalized mean absolute error increased nonlinearly with decreasing SNR. CS increased the mean SNR of NA 129Xe images 3-fold.
Conclusion
CS reconstruction of dissolved 129Xe imaging improved image quality with decreased scan time, while preserving key gas exchange metrics. This will benefit patients with breathlessness and/or low gas transfer and shows promise for NA-dissolved 129Xe imaging
A framework for modelling whole-lung and regional TLCO using hyperpolarised 129Xe lung MRI
Background: Pulmonary gas exchange is assessed by the transfer factor of the lungs (TL) for carbon monoxide (TLCO), and can also be measured with inhaled xenon-129 (129Xe) MRI. A model has been proposed to estimate TL from 129Xe MRI metrics, but this approach has not been fully validated and does not utilise the spatial information provided by 3D 129Xe MRI.
Methods: Three models for predicting TL from 129Xe MRI metrics were compared; (1) a previously-published physiology-based model, (2) multivariable linear regression and (3) random forest regression. Models were trained on data from 150 patients with asthma and/or chronic obstructive pulmonary disease. The random forest model was applied voxel-wise to 129Xe images to yield regional TL maps.
Results: Coefficients of the physiological model were found to differ from previously reported values. All models had good prediction accuracy with small mean absolute error (MAE); (1) 1.24±0.15â
mmol·minâ1·kPaâ1, (2) 1.01±0.06â
mmol·minâ1·kPaâ1, (3) 0.995±0.129â
mmol·minâ1·kPaâ1. The random forest model performed well when applied to a validation group of post-COVID-19 patients and healthy volunteers (MAE=0.840â
mmol·minâ1·kPaâ1), suggesting good generalisability. The feasibility of producing regional maps of predicted TL was demonstrated and the whole-lung sum of the TL maps agreed with measured TLCO (MAE=1.18â
mmol·minâ1·kPaâ1).
Conclusion: The best prediction of TLCO from 129Xe MRI metrics was with a random forest regression framework. Applying this model on a voxel-wise level to create parametric TL maps provides a useful tool for regional visualisation and clinical interpretation of 129Xe gas exchange MRI
Mapping the amplitude and phase of dissolved 129 Xe red blood cell signal oscillations with keyhole spectroscopic lung imaging
Purpose
To assess the regional amplitude and phase of dissolved 129Xe red blood cell (RBC) signal oscillations in the lung vasculature with keyhole spectroscopic imaging and to compare with previous methodology, which does not account for oscillation phase.
Methods
129Xe gas transfer was measured with a four-echo 3D radial spectroscopic imaging sequence. Keyhole reconstruction-based RBC signal oscillation amplitude mapping was applied retrospectively to data acquired from 28 healthy volunteers, 4 chronic thromboembolic pulmonary hypertension (CTEPH) patients, and 5 patients who were hospitalized due to COVID-19 pneumonia and had residual lung abnormalities. Using a sliding window keyhole reconstruction, maps of RBC oscillation amplitude were corrected for regional phase difference. Repeatability of the phase-adjusted oscillation amplitude was assessed in 8 healthy volunteers across three scans.
Results
With sliding window keyhole reconstruction, regional phase differences were observed in the RBC signal oscillations: mean phaseâ=â(0.27â±â0.19) rad in healthy volunteers, (0.24â±â0.13) rad in CTEPH patients, and (0.33â±â0.19) rad in patients with post-COVID-19 residual lung abnormality. The oscillation amplitude and phase maps were more heterogeneous (i.e., they showed increased coefficient of variation) for the CTEPH patients. The RBC oscillation amplitude was repeatable, and the mean three-scan coefficient of variation was smaller when the phase adjustment was made (0.07â±â0.04 compared with 0.16â±â0.05).
Conclusion
Sliding window keyhole reconstruction of radial dissolved 129Xe imaging reveals regional phase differences in the RBC oscillations, which are not captured when performing two phase keyhole reconstruction. This regional phase information may reflect the hemodynamic effect of the cardiac pulse wave in the pulmonary microvasculature
PENGARUH TERPAAN BERITA PERKOSAAN DI TRIBUNNEWS.COM TERHADAP SIKAP WASPADA MAHASISWI
The research problem in this research includes whether there is the influence of rape news of UGM female student in Tribunnews.com towards female students vigilant attitude in interact and how the influence imposed. Variable X in this research is rape news, while vigilant attitude of female students in interact is variable Y.
Quantitative research is implemented by means of associative type. In addition, the basic research is survey method. The population in this study is female students second period of KKN 2018/2019 University of Muhammadiyah Malang and 36 of them become the research sample. Questionnaires and documentation are implemented as data collection techniques. Validity and reliability test are also implemented as the research instrument test. Furthermore, the researcher conducts simple linear regression and hypothesis testing using the t test as data analysis techniques.
The coefficient of variable X is 0.716 (positive). From the analysis results obtained that R square result (the coefficient of determination) is 0.130. R value (the correlation coefficient) is 0.361, it shows the correlation between news rape of UGM female student in Tribunnews.com towards female students vigilant attitude in interact (Y) are included in a weak category. On the other hand, t table (α = 0.05; df residual = 34) is 1.690. Since t arithmetic > t table is 2.255 > 1.690 or sig. t value (0.031) < α = 0.05, the influence of X (rape news of UGM female student in Tribunnews.com) towards Y (female students vigilant attitude in interact) is significant.
In accordance with the analysis above, it can be concluded that 13% of female students vigilant attitude in interact variable (Y) is influenced by independent variable, namely rape news of UGM female student in Tribunnews.com, and yet 87% of female students vigilant attitude in interact variable is influenced by other variables
Whirl mappings on generalised annuli and the incompressible symmetric equilibria of the dirichlet energy
In this paper we show a striking contrast in the symmetries of equilibria and extremisers of the total elastic energy of a hyperelastic incompressible annulus subject to pure displacement boundary conditions.Indeed upon considering the equilibrium equations, here, the nonlinear second order elliptic system formulated for the deformation u=(u1,âŠ,uN) :
EL[u,X]=â§â©âšâȘâȘÎu=div(P(x)cofâu)detâu=1uâĄÏinX,inX,onâX,
where X is a finite, open, symmetric N -annulus (with Nâ„2 ), P=P(x) is an unknown hydrostatic pressure field and Ï is the identity mapping, we prove that, despite the inherent rotational symmetry in the system, when N=3 , the problem possesses no non-trivial symmetric equilibria whereas in sharp contrast, when N=2 , the problem possesses an infinite family of symmetric and topologically distinct equilibria. We extend and prove the counterparts of these results in higher dimensions by way of showing that a similar dichotomy persists between all odd vs. even dimensions Nâ„4 and discuss a number of closely related issues
On a class of stationary loops on SO(n) and the existence of multiple twisting solutions to a nonlinear elliptic system subject to a hard incompressibility constraint
For full abstract please refer to http://dx.doi.org/10.1186/s13661-018-1047-
- âŠ