581 research outputs found
Hydrogeochemistry of the Caribou-Poker Creeks Research Watershed
Bedrock of the Caribou-Poker Creeks Research Watershed dissolves incongruently
with a first-order rate constant of about 5 x 10-6 day-1 at 5° C. The
resulting solution is potassium-calcium-magnesium rich. The soil-plant environment
acts on this solution through sorption of potassium and by evapotranspiration
to yield a solution that is relatively depleted in potassium and
enriched in calcium and magnesium, but with the same molar ratio of Ca:Mg as
the fluid from the rock dissolution. This fluid from the soil-plant reservoir
is the dominant contributor of ions to stream waters.
Using the discriminant functions obtained by multiple discriminant
analysis
DPKR = 0.572Si02 + 0.240Ca + 2.89Mg - 0.384Na + 0.452N03 - 9.18
DCRB = 0.913Si02 + 0.042Ca + 1.28Mg + 1.17Na + 4.63N03 - 7.27,
the waters of Caribou Creek and Poker Creek can be distinguished on the basis
of chemical composition. In general, Poker Creek waters are slightly more
concentrated than Caribou Creek waters.
On the average, 1.4 x 10^13g H20/year leaves the watershed as surface
water. At an average calcium concentration of 14 ppm for the water, 0.1% for
the bedrock, and a watershed area of 46 mi^2, this flow corresponds to a maximum
loss of about 17 metric tons of rock per hectare per year
Geology and Geochemistry of the Ship Creek and Monashka Creek reservoirs, Southcentral Alaska
Graywacke from the Ship Creek watershed, dissolves incongruently in distilled water. The dissolution appears to follow a first-order rate law which in integrated form is:
k = -2.303/t log No-Q/No
where No is the concentration in ppm of Ca, Mg, Na or K in the graywacke,
Q is the total quantity of these ions leached in time t(days), k is the rate constant in days-1. Experimentally derived rate constants for the dissolution of graywacke in distilled water at 5oC are log k+2CA, -4.128 day-1; log k+2Mg, -6.174 day-1; log k+Na, -5.800 day-1; and log k+K, -5.249 day-1. The above constants are for 40 to +100 mesh graywacke. A surface area correction term must be inserted in the above equation if it is applied to a different size fraction.
Using the above equation and rate constants, the chemical composition of a water in contact with graywacke was calculated. With the exception of magnesium, the agreement between the calculated composition and that of Ship Creek water was good. Assuming that the groundwater in the Ship Creek
watershed contacts about 1.5X104cm2 graywacke per liter, 120 to 360 days
are required at 5oC to produce the concentration of ions observed in Ship
Creek.
Release of exchangeable H+ from the soil mat to the reservoir water will not significant1y lower the pH of the water.
Leaching of heavy metals from sulfides contained in the bedrock of
the two watersheds does not pose a water quality hazard.
Lineaments in the bedrock at Monashka Creek may provide channels through which water may seep from the reservoir. These are not expected to pose a problem in retaining water in the reservoir, but they may result in small, new springs down grade from the reservoir.The work upon which this report is based was supported by funds provided
by the United States Department of the Interior, Office of Water
Resources Research and Technology, as authorized by the Water Resources
Research Act of 1964, Public Law 88-379, as amended. (Project A-045-ALAS
Arsenic in the Water, Soil Bedrock, and Plants of the Ester Dome Area of Alaska
Concentrations of arsenic as large as 10 ppm (200 times the safe
limit for drinking water) occur in the groundwater of a mineralized
residential area near Fairbanks. Bedrock of the area contains 750 ppm
As, primarily as arsenopyrite and scorodite. The oxygen-poor groundwater
is enriched in As(III) and ferrous iron while the surface waters
are iron free and contain less than 50 ppb As(V). Arsenic is removed
from the water by coprecipitation with ferric hydroxide. Some iron-rich
stream sediments contain as much as 1,400 ppm arsenic.
The distribution of arsenic in the groundwater is controlled by the
distribution of arsenic in the bedrock. The arsenic content of the B soil
horizon over mineralized veins is about 150 ppm, while that over barren
rock is 30 ppm. The vegetation over the veins is not significantly
enriched in arsenic.
Lettuce, radishes and tomatoes grown with arsenic-rich water (5 ppm) contain 16, 8 and 1 ppm As, respectively; these amounts are significantly
greater than plants not treated with arsenic.
Preliminary studies by state and federal health agencies show no
detrimental effects on the health of persons drinking these arsenic-rich
waters.The work upon which this publication is based was supported in part by
funds provided by the Office of Water Research and Technology (Project
B-037-ALAS, Agreement No. 14-34-0001-8056), U.S. Department of the
Interior, Washington, D.C., as authorized by the Water Research and
Development Act of 1978
Overrating Bruins, Underrating Badgers: Media, Bias, and College Basketball
Why are some teams perennial darlings of sports journalists while other talented squads get overlooked? Each week during the NCAA basketball season, the Associated Press releases a ranked poll of the top 25 teams. By comparing the preseason and postseason rankings, we construct a measure of how much sports journalists who respond to the poll overrate (or underrate) college teams relative to their actual performance. Using this metric for the 115 NCAA schools that have appeared at least once in the opening or final AP poll in the last 25 years, we examine a range of institutional characteristics that may predict overrating or underrating by members of the sports media. A multilevel analysis reveals that recent performance in the NCAA tournament and the perceived quality of the most recent recruiting class are the strongest predictors of being consistently overrated. While no institutional characteristics had direct effects, the effect of tournament performance on overrating is greater for teams that have historically had fewer coaches and compete in a âpowerâ conference, and for national research institutions with larger student bodies. Our findings have implications for understanding how complex decisions are made within a conservative social institution (the media) and suggest that some schools may receive advantages in media exposure and financial opportunity
Big GAAP/Little GAAP: Will The Debate Ever End?
There has been an ongoing debate for decades, especially since the inception of the Financial Accounting Standards Board (FASB), over the appropriate application of generally accepted accounting principles (GAAP) to private companies. This so-called âBig GAAP vs. Little GAAPâ debate has now come to a crisis point. The Financial Accounting Foundation (FAF) has taken a position that is contrary to the recommendations of the Blue Ribbon Panel on Standard Setting for Private Companies (the Panel) presented in January 2011, despite having been represented on the Panel. The American Institute of Certified Public Accountants (AICPA), also represented on the Panel, has responded by taking a strong stand in favor of the Panelâs position and against the new FAF recommendation and Invitation to Comment, published on October 4, 2011. Additionally, the International Accounting Standards Board has developed a set of reporting standards for small and medium size enterprises (IFRS for SMEs) that has not been recognized in the US. In this paper, we examine the history of the Big GAAP/Little GAAP debate in the US and internationally. We find substantial support for reducing requirements of private companies and recommend that International Financial Reporting Standards for Small to Medium-Sized Enterprises (IFRS for SMEs) be used for public companies of all sizes to be consistent with standards that have been accepted globally
Chemical Doppelgangers in GALAH DR3: the Distinguishing Power of Neutron-Capture Elements Among Milky Way Disk Stars
The observed chemical diversity of Milky Way stars places important
constraints on Galactic chemical evolution and the mixing processes that
operate within the interstellar medium. Recent works have found that the
chemical diversity of disk stars is low. For example, the APOGEE "chemical
doppelganger rate," or the rate at which random pairs of field stars appear as
chemically similar as stars born together, is high, and the chemical
distributions of APOGEE stars in some Galactic populations are well-described
by two-dimensional models. However, limited attention has been paid to the
heavy elements (Z > 30) in this context. In this work, we probe the potential
for neutron-capture elements to enhance the chemical diversity of stars by
determining their effect on the chemical doppelganger rate. We measure the
doppelganger rate in GALAH DR3, with abundances rederived using The Cannon, and
find that considering the neutron-capture elements decreases the doppelganger
rate from 2.2% to 0.4%, nearly a factor of 6, for stars with -0.1 < [Fe/H] <
0.1. While chemical similarity correlates with similarity in age and dynamics,
including neutron-capture elements does not appear to select stars that are
more similar in these characteristics. Our results highlight that the
neutron-capture elements contain information that is distinct from that of the
lighter elements and thus add at least one dimension to Milky Way abundance
space. This work illustrates the importance of considering the neutron-capture
elements when chemically characterizing stars and motivates ongoing work to
improve their atomic data and measurements in spectroscopic surveys.Comment: 23 pages, 16 figures, 1 table. Submitted to AAS Journals, comments
welcome. Associated catalog of high precision, Cannon-rederived abundances
for GALAH giants to be made publicly available upon acceptance and available
now upon request. See Walsen et al. 2023 for a complementary, high precision,
Cannon-rederived abundance catalog for GALAH solar twin
Novel critical point drying (CPD) based preparation and transmission electron microscopy (TEM) imaging of protein specific molecularly imprinted polymers (HydroMIPs)
We report the transmission electron microscopy (TEM) imaging of a hydrogel-based molecularly imprinted polymer (HydroMIP) specific to the template molecule bovine haemoglobin (BHb). A novel critical point drying based sample preparation technique was employed to prepare the molecularly imprinted polymer (MIP) samples in a manner that would facilitate the use of TEM to image the imprinted cavities, and provide an appropriate degree of both magnification and resolution to image polymer architecture in the <10 nm range. For the first time, polymer structure has been detailed that clearly displays molecularly imprinted cavities, ranging from 5-50 nm in size, that correlate (in terms of size) with the protein molecule employed as the imprinting template. The modified critical point drying sample preparation technique used may potentially play a key role in the imaging of all molecularly imprinted polymers, particularly those prepared in the aqueous phase
A Spectroscopic Survey of Faint Quasars in the SDSS Deep Stripe: I. Preliminary Results from the Co-added Catalog
In this paper we present the first results of a deep spectroscopic survey of
faint quasars in the Sloan Digital Sky Survey (SDSS) Southern Survey, a deep
survey carried out by repeatedly imaging a 270 deg^2 area. Quasar candidates
were selected from the deep data with good completeness over 0<z<5, and 2 to 3
magnitudes fainter than the SDSS main survey. Spectroscopic follow-up was
carried out on the 6.5m MMT with Hectospec. The preliminary sample of this SDSS
faint quasar survey (hereafter SFQS) covers ~ 3.9 deg^2, contains 414 quasars,
and reaches g=22.5. The overall selection efficiency is ~ 66% (~ 80% at
g<21.5); the efficiency in the most difficult redshift range (2<z<3) is better
than 40%. We use the 1/V_{a} method to derive a binned estimate of the quasar
luminosity function (QLF) and model the QLF using maximum likelihood analysis.
The best model fits confirm previous results showing that the QLF has steep
slopes at the bright end and much flatter slopes (-1.25 at z<2.0 and -1.55 at
z>2.0) at the faint end, indicating a break in the QLF slope. Using a
luminosity-dependent density evolution model, we find that the quasar density
at M_{g}<-22.5 peaks at z~2, which is later in cosmic time than the peak of
z~2.5 found from surveys of more luminous objects. The SFQS QLF is consistent
with the results of the 2dF QSO Redshift Survey, the SDSS, and the 2dF-SDSS LRG
and QSO Survey, but probes fainter quasars. We plan to obtain more quasars from
future observations and establish a complete faint quasar sample with more than
1000 objects over 10 deg^2.Comment: 25 pages, 13 figures, accepted for publication in A
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The metabolome regulates the epigenetic landscape during naive-to-primed human embryonic stem cell transition.
For nearly a century developmental biologists have recognized that cells from embryos can differ in their potential to differentiate into distinct cell types. Recently, it has been recognized that embryonic stem cells derived from both mice and humans exhibit two stable yet epigenetically distinct states of pluripotency: naive and primed. We now show that nicotinamide N-methyltransferase (NNMT) and the metabolic state regulate pluripotency in human embryonic stem cells (hESCs). Â Specifically, in naive hESCs, NNMT and its enzymatic product 1-methylnicotinamide are highly upregulated, and NNMT is required for low S-adenosyl methionine (SAM) levels and the H3K27me3 repressive state. NNMT consumes SAM in naive cells, making it unavailable for histone methylation that represses Wnt and activates the HIF pathway in primed hESCs. These data support the hypothesis that the metabolome regulates the epigenetic landscape of the earliest steps in human development
Counting the Acid Sites in a Commercial ZSM-5 Zeolite Catalyst
This work was funded by Johnson Matthey plc. through the provision of industrial CASE studentships in partnership with the EPSRC (AZ (EP/N509176/1), APH (EP/P510506/1)). Experiments at the ISIS Neutron and Muon Source were made possible by beam time allocations from the Science and Technologies Facilities Council.45,46 Resources and support were provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1Peer reviewedPublisher PD
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