39,717 research outputs found
An Evaluation of the Effect of Discharging a High Quality Effluent into a Small Ozark Mountain Stream
Recently the newly constructed Fayetteville wastewater treatment plant went on line and directed a portion of its discharge to a point in the Mud Creek drainage basin that had previously not received any effluent. Prior to the discharge, a background study had been performed to establish the water quality in the basin. The background data, when compared to the data collected by this study, allowed any alteration of the stream water quality to be evaluated. Also the modeling procedure used to set the effluent limits for the treatment plant was analyzed. All stream data were compared to the limits set forth for surface water quality by the Department of Pollution Control and Ecology. The new discharge had some effect on the receiving stream, however, the stream still meets Arkansas water quality standards for all parameters
Impact of COVID-19 and Future Emerging Viruses on Hematopoietic Cell Transplantation and Other Cellular Therapies
COVID-19, where Co stands for corona, VI stands for virus, and D denotes disease, in the recent past referred to as 2019 novel coronavirus or 2019-nCoV, has impacted numerous lives and businesses, and has led to a surreal emergency state within world communities. COVID-19 and the future emergence of dangerous viruses will have strong and as yet possibly unanticipated consequences and impact on the present and future use of cellular therapies. In this commentary, we offer a dispassionate assessment of where we believe COVID-19, as well as future emerging viruses, might compromise successful cell transplantation (Fig. 1). These therapies include hematopoietic cell transplantation (HCT) using umbilical cord blood (CB), bone marrow (BM), and mobilized peripheral blood, which contain hematopoietic stem (HSC) and progenitor (HPC) cells, as well as various cellular populations involved in the emerging fields of reparative and regenerative medicine. Such cell populations include HSC, HPC, mesenchymal stem/stromal cells (MSC), and immune cells such as lymphocytes used in chimeric antigen receptor (CAR) T-cell therapies, as well as pluripotent stem cell–based therapies
Iterative methods for plasma sheath calculations: Application to spherical probe
The computer cost of a Poisson-Vlasov iteration procedure for the numerical solution of a steady-state collisionless plasma-sheath problem depends on: (1) the nature of the chosen iterative algorithm, (2) the position of the outer boundary of the grid, and (3) the nature of the boundary condition applied to simulate a condition at infinity (as in three-dimensional probe or satellite-wake problems). Two iterative algorithms, in conjunction with three types of boundary conditions, are analyzed theoretically and applied to the computation of current-voltage characteristics of a spherical electrostatic probe. The first algorithm was commonly used by physicists, and its computer costs depend primarily on the boundary conditions and are only slightly affected by the mesh interval. The second algorithm is not commonly used, and its costs depend primarily on the mesh interval and slightly on the boundary conditions
Design considerations and test facilities for accelerated radiation effects testing
Test design parameters for accelerated dose rate radiation effects tests for spacecraft parts and subsystems used in long term mission (years) are detailed. A facility for use in long term accelerated and unaccelerated testing is described
Particle creation in a Robertson-Walker Universe revisited
We reanalyze the problem of particle creation in a 3+1 spatially closed
Robertson-Walker space-time. We compute the total number of particles produced
by this non-stationary gravitational background as well as the corresponding
total energy and find a slight discrepancy between our results and those
recently obtained in the literatur
The Absolute Magnitude Distribution of Kuiper Belt Objects
Here we measure the absolute magnitude distributions (H-distribution) of the
dynamically excited and quiescent (hot and cold) Kuiper Belt objects (KBOs),
and test if they share the same H-distribution as the Jupiter Trojans. From a
compilation of all useable ecliptic surveys, we find that the KBO
H-distributions are well described by broken power-laws. The cold population
has a bright-end slope, , and break
magnitude, (r'-band). The hot population has
a shallower bright-end slope of, , and
break magnitude . Both populations share
similar faint end slopes of . We estimate the masses of the
hot and cold populations are and \sim3\times10^{-4} \mbox{
M_{\bigoplus}}. The broken power-law fit to the Trojan H-distribution has
, , and
. The KS test reveals that the probability that the Trojans
and cold KBOs share the same parent H-distribution is less than 1 in 1000. When
the bimodal albedo distribution of the hot objects is accounted for, there is
no evidence that the H-distributions of the Trojans and hot KBOs differ. Our
findings are in agreement with the predictions of the Nice model in terms of
both mass and H-distribution of the hot and Trojan populations. Wide field
survey data suggest that the brightest few hot objects, with
, do not fall on the steep power-law slope of fainter
hot objects. Under the standard hierarchical model of planetesimal formation,
it is difficult to account for the similar break diameters of the hot and cold
populations given the low mass of the cold belt.Comment: Accepted to the Astrophysical Journa
Properties of AGN coronae in the NuSTAR era
The focussing optics of NuSTAR have enabled high signal-to-noise spectra to
be obtained from many X-ray bright Active Galactic Nuclei (AGN) and Galactic
Black Hole Binaries (BHB). Spectral modelling then allows robust
characterization of the spectral index and upper energy cutoff of the coronal
power-law continuum, after accounting for reflection and absorption effects.
Spectral-timing studies, such as reverberation and broad iron line fitting, of
these sources yield coronal sizes, often showing them to be small and in the
range of 3 to 10 gravitational radii in size. Our results indicate that coronae
are hot and radiatively compact, lying close to the boundary of the region in
the compactness - temperature diagram which is forbidden due to runaway pair
production. The coincidence suggests that pair production and annihilation are
essential ingredients in the coronae of AGN and BHB and that they control the
shape of the observed spectra.Comment: 11 pages, 8 figures, accepted for publication in MNRA
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