1,630 research outputs found
The CCSM4 ocean component
Author Posting. © American Meteorological Society, 2012. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 25 (2012): 1361–1389, doi:10.1175/JCLI-D-11-00091.1.The ocean component of the Community Climate System Model version 4 (CCSM4) is described, and its solutions from the twentieth-century (20C) simulations are documented in comparison with observations and those of CCSM3. The improvements to the ocean model physical processes include new parameterizations to represent previously missing physics and modifications of existing parameterizations to incorporate recent new developments. In comparison with CCSM3, the new solutions show some significant improvements that can be attributed to these model changes. These include a better equatorial current structure, a sharper thermocline, and elimination of the cold bias of the equatorial cold tongue all in the Pacific Ocean; reduced sea surface temperature (SST) and salinity biases along the North Atlantic Current path; and much smaller potential temperature and salinity biases in the near-surface Pacific Ocean. Other improvements include a global-mean SST that is more consistent with the present-day observations due to a different spinup procedure from that used in CCSM3. Despite these improvements, many of the biases present in CCSM3 still exist in CCSM4. A major concern continues to be the substantial heat content loss in the ocean during the preindustrial control simulation from which the 20C cases start. This heat loss largely reflects the top of the atmospheric model heat loss rate in the coupled system, and it essentially determines the abyssal ocean potential temperature biases in the 20C simulations. There is also a deep salty bias in all basins. As a result of this latter bias in the deep North Atlantic, the parameterized overflow waters cannot penetrate much deeper than in CCSM3.NCAR is sponsored by the National
Science Foundation. The CCSM is also sponsored by
the Department of Energy. SGY was supported by the
NOAA Climate Program Office under Climate Variability
and Predictability Program Grant NA09OAR4310163.2012-09-0
Pressure Induced Topological Phase Transitions in Membranes
Some highly unusual features of a lipid-water liquid crystal are revealed by
high pressure x-ray diffraction, light scattering and dilatometric studies of
the lamellar (bilayer ) to nonlamellar inverse hexagonal ()
phase transition. (i) The size of the unit cell of the phase increases
with increasing pressure. (ii) The transition volume, ,
decreases and appears to vanish as the pressure is increased. (iii) The
intensity of scattered light increases as decreases. Data are
presented which suggest that this increase is due to the formation of an
intermediate cubic phase, as predicted by recent theoretical suggestions of the
underlying universal phase sequence.Comment: 12 pages, typed using REVTEX 2.
Surveillance of RNase P, PMMoV, and CrAssphage in wastewater as indicators of human fecal concentration across urban sewer neighborhoods, Louisville, Kentucky
Wastewater surveillance has been widely used as a supplemental method to track the community infection levels of severe acute respiratory syndrome coronavirus 2. A gap exists in standardized reporting for fecal indicator concentrations, which can be used to calibrate the primary outcome concentrations from wastewater monitoring for use in epidemiological models. To address this, measurements of fecal indicator concentration among wastewater samples collected from sewers and treatment centers in four counties of Kentucky (N = 650) were examined. Results from the untransformed wastewater data over 4 months of sampling indicated that the fecal indicator concentration of human ribonuclease P (RNase P) ranged from 5.1 × 101 to 1.15 × 106 copies/ml, pepper mild mottle virus (PMMoV) ranged from 7.23 × 103 to 3.53 × 107 copies/ml, and cross-assembly phage (CrAssphage) ranged from 9.69×103 to 1.85×108 copies/ml. The results showed both regional and temporal variability. If fecal indicators are used as normalization factors, knowing the daily sewer system flow of the sample location may matter more than rainfall. RNase P, while it may be suitable as an internal amplification and sample adequacy control, has less utility than PMMoV and CrAssphage as a fecal indicator in wastewater samples when working at different sizes of catchment area. The choice of fecal indicator will impact the results of surveillance studies using this indicator to represent fecal load. Our results contribute broadly to an applicable standard normalization factor and assist in interpreting wastewater data in epidemiological modeling and monitoring
Improved Imputation of Common and Uncommon Single Nucleotide Polymorphisms (SNPs) with a New Reference Set
Statistical imputation of genotype data is an important technique for analysis of genome-wide association studies (GWAS). We have built a reference dataset to improve imputation accuracy for studies of individuals of primarily European descent using genotype data from the Hap1, Omni1, and Omni2.5 human SNP arrays (Illumina). Our dataset contains 2.5-3.1 million variants for 930 European, 157 Asian, and 162 African/African-American individuals. Imputation accuracy of European data from Hap660 or OmniExpress array content, measured by the proportion of variants imputed with R^2^>0.8, improved by 34%, 23% and 12% for variants with MAF of 3%, 5% and 10%, respectively, compared to imputation using publicly available data from 1,000 Genomes and International HapMap projects. The improved accuracy with the use of the new dataset could increase the power for GWAS by as much as 8% relative to genotyping all variants. This reference dataset is available to the scientific community through the NCBI dbGaP portal. Future versions will include additional genotype data as well as non-European populations
Target Zones in History and Theory: Lessons from an Austro-Hungarian Experiment (1896-1914)
The first known experiment with an exchange rate band took place in Austria-
Hungary between 1896 and 1914. The rationale for introducing this policy rested
on precisely those intuitions that the modern literature has emphasized: the band
was designed to secure both exchange rate stability and monetary policy
autonomy. However, unlike more recent experiences, such as the ERM, this
policy was not undermined by credibility problems. The episode provides an ideal
testing ground for some important ideas in modern macroeconomics: specifically,
can formal rules, when faithfully adhered to, provide policy makers with some
advantages such as short term autonomy? First, we find that a credible band has a
"microeconomic" influence on exchange rate stability. By reducing uncertainty, a
credible fluctuation band improves the quality of expectations, a channel that has been neglected in the modern literature. Second, we show that the standard test of the basic target zone model is flawed and develop an alternative methodology. We believe that these findings shed a new light on the economics of exchange rate bands
Performance, Carcass Characteristics, and Life Cycle Assessment of Cattle Grown Utilizing Different Combinations of Growth Promoting Technologies
The objective of this study was to determine the impact of different combinations of growth promoting technologies on live animal performance, carcass characteristics, and environmental outcomes
Credibility and adjustment: gold standards versus currency boards
It is often maintained that currency boards (CBs) and gold standards (GSs) are alike in that they are stringent monetary rules, the two basic features of which are high credibility of monetary authorities and the existence of automatic adjustment (non discretionary) mechanism. This article includes a comparative analysis of these two types of regimes both from the perspective of the sources and mechanisms of generating confidence and credibility, and the elements of operation of the automatic adjustment mechanism. Confidence under the GS is endogenously driven, whereas it is exogenously determined under the CB. CB is a much more asymmetric regime than GS (the adjustment is much to the detriment of peripheral countries) although asymmetry is a typical feature of any monetary regime. The lack of credibility is typical for peripheral countries and cannot be overcome completely even by “hard” monetary regimes.http://deepblue.lib.umich.edu/bitstream/2027.42/40078/3/wp692.pd
The CO emission in the Taffy Galaxies (UGC 12914/5) at 60pc resolution-I: The battle for star formation in the turbulent Taffy Bridge
We present ALMA observations at a spatial resolution of 0.2 arcsec (60 pc) of
CO emission from the Taffy galaxies (UGC 12914/5). The observations are
compared with narrow-band Pa, mid-IR, radio continuum and X-ray
imaging, plus optical spectroscopy. The galaxies have undergone a recent
head-on collision, creating a massive gaseous bridge which is known to be
highly turbulent. The bridge contains a complex web of narrow molecular
filaments and clumps. The majority of the filaments are devoid of star
formation, and fall significantly below the Kennicutt-Schmidt relationship for
normal galaxies, especially for the numerous regions undetected in Pa
emission. Within the loosely connected filaments and clumps of gas we find
regions of high velocity dispersion which appear gravitationally unbound for a
wide range of likely values of . Like the "Firecracker" region in
the Antennae system, they would require extremely high external dynamical or
thermal pressure to stop them dissipating rapidly on short crossing timescales
of 2-5~Myrs. We suggest that the clouds may be transient structures within a
highly turbulent multi-phase medium which is strongly suppressing star
formation. Despite the overall turbulence in the system, stars seem to have
formed in compact hotspots within a kpc-sized extragalactic HII region, where
the molecular gas has a lower velocity dispersion than elsewhere, and shows
evidence for a collision with an ionized gas cloud. Like the shocked gas in the
Stephan's Quintet group, the conditions in the Taffy bridge shows how difficult
it is to form stars within a turbulent, multi-phase, gas.Comment: 23 pages, 1 Appendix, 17 figure
Comments on the Mechanism of Aging of Antimony Doped Tin Oxide Based Electrochromic Devices
Electrochromic effects of antimony doped tin oxide (ATO) nanoparticles are investigated to probe device yellowing (degradation). Voltage vs contrast ratio curves exhibit hysteresis, i.e., image-sticking phenomena due to irreversible charge insertion. X-ray, impedance and optical b* studies suggest that the yellowing/charge trapping is nanoparticle size-dependent with 4 nm size particles exhibiting the least yellowing. Yellowing results in increased impedances of electrode–electrolyte interface and electrode corrosion. Plausible sources of discoloration are formation of insulating complex alkali oxide film, carrier inversion (n-to-p type) through electrochemical Li doping, redeposition of the corroded electrode material and perhaps residual concentration of charge-transfer species
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