3,288 research outputs found
Biological Effects of Dispersants and Dispersed Oil in Surface and Deep Ocean Species
Beginning with the use of industrial-strength detergents, dispersing agents have been employed in spill response for decades. The Corexit series of agents in common use today generally consist of non-ionic and/or anionic surfactants in a solvent base designed to enhance miscibility under varying temperature and salinity conditions; cationic surfactants tend to be too toxic for use. While dispersants generally serve to decrease the interfacial surface tension of oil, thus facilitating its weathering under low-energy conditions, their surface-active nature also causes their interaction with cell surfaces – those of single-celled organisms as well as the gills of vertebrates and invertebrates
Response-to-noise studies of some aircraft and spacecraft structures
Fatigue and response to noise of aircraft and spacecraft viscoelastic panels, shell structure, and payload
Welfare-maximizing monetary policy under parameter uncertainty
This paper examines welfare-maximizing monetary policy in an estimated micro-founded general equilibrium model of the U.S. economy where the policymaker faces uncertainty about model parameters. Uncertainty about parameters describing preferences and technology implies not only uncertainty about the dynamics of the economy. It also implies uncertainty about the model's utility-based welfare criterion and about the economy's natural rate measures of interest and output. We analyze the characteristics and performance of alternative monetary policy rules given the estimated uncertainty regarding parameter estimates. We find that the natural rates of interest and output are imprecisely estimated. We then show that, relative to the case of known parameters, optimal policy under parameter uncertainty responds less to natural-rate terms and more to other variables, such as price and wage inflation and measures of tightness or slack that do not depend on natural rates.Monetary policy
Discovery of a Large-scale Wall in the Direction of Abell 22
We report on the discovery of a large-scale wall in the direction of Abell
22. Using photometric and spectroscopic data from the Las Campanas Observatory
and Anglo-Australian Telescope Rich Cluster Survey, Abell 22 is found to
exhibit a highly unusual and striking redshift distribution. We show that Abell
22 exhibits a foreground wall-like structure by examining the galaxy
distributions in both redshift space and on the colour-magnitude plane. A
search for other galaxies and clusters in the nearby region using the 2dF
Galaxy Redshift Survey database suggests that the wall-like structure is a
significant large-scale, non-virialized filament which runs between two other
Abell clusters either side of Abell 22. The filament stretches over at least
>40 Mpc in length and 10 Mpc in width at the redshift of Abell 22.Comment: 6 pages, 4 figures, accepted for publication in MNRAS letter
Employment in a drug manufacturing industry
Thesis (M.B.A.)--Boston Universit
The ROSAT Deep Cluster Survey: the X-ray Luminosity Function out to z=0.8
We present the X-ray Luminosity Function (XLF) of the ROSAT Deep Cluster
Survey (RDCS) sample over the redshift range 0.05-0.8. Our results are derived
from a complete flux-limited subsample of 70 galaxy clusters, representing the
brightest half of the total sample, which have been spectroscopically
identified down to the flux limit of 4*10^{-14} erg/cm^2/s (0.5-2.0 keV) and
have been selected via a serendipitous search in ROSAT-PSPC pointed
observations. The redshift baseline is large enough that evolutionary effects
can be studied within the sample. The local XLF (z < 0.25) is found to be in
excellent agreement with previous determinations using the ROSAT All-Sky Survey
data. The XLF at higher redshifts, when combined with the deepest number counts
constructed to date (f>2*10^{-14} arg/cm^2/s), reveal no significant evolution
at least out to z=0.8, over a luminosity range 2*10^{42}-3*10^{44} erg/s in the
[0.5-2 keV] band. These findings extend the study of cluster evolution to the
highest redshifts and the faintest fluxes probed so far in X-ray surveys. They
complement and do not necessarily conflict with those of the Einstein Extended
Medium Sensitivity Survey, leaving the possibility of negative evolution of the
brightest end of the XLF at high redshifts.Comment: 12 pages, 4 figures, LaTeX (aasms4.sty). To appear in ApJ Letter
Statistical Topological Insulators
We define a class of insulators with gapless surface states protected from
localization due to the statistical properties of a disordered ensemble, namely
due to the ensemble's invariance under a certain symmetry. We show that these
insulators are topological, and are protected by a invariant.
Finally, we prove that every topological insulator gives rise to an infinite
number of classes of statistical topological insulators in higher dimensions.
Our conclusions are confirmed by numerical simulations.Comment: 6 pages, 1 table, 5 figures, this is the final, published versio
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