Transport and Fate of River Discharge on the Continental Shelf of the Southeastern United States

We have analyzed 8 years of wind and salinity data from a frontal zone in a region of the inner continental shelf off the southeastern United States. The changes in low‐salinity water stored in the frontal zone have been parameterized by analyzing the monthly rate of change in freshwater content. When the rate of change in freshwater content was negative, we interpreted this as a loss of low‐salinity water from the frontal zone. When this parameter was compared with seasonally averaged alongshore wind stress, the rate of loss was independent of the alongshore wind stress magnitude until threshold of about 0.1 dyne cm−2 was reached. Above the threshold there was a clear relationship between northward alongshore wind stress and rate of loss of freshwater from the inner shelf. Experimental evidence suggests that horizontal currents in the inner‐shelf frontal zone have cyclonic shear with increasing depth. When wind stress is northward and offshore, near‐surface low‐salinity water is transported offshore by Ekman transport while near‐bottom high‐salinity water is transported shoreward

Galaxy clustering and projected density profiles as traced by satellites in photometric surveys: Methodology and luminosity dependence

We develop a new method which measures the projected density distribution w_p(r_p)n of photometric galaxies surrounding a set of spectroscopically-identified galaxies, and simultaneously the projected correlation function w_p(r_p) between the two populations. In this method we are able to divide the photometric galaxies into subsamples in luminosity intervals when redshift information is unavailable, enabling us to measure w_p(r_p)n and w_p(r_p) as a function of not only the luminosity of the spectroscopic galaxy, but also that of the photometric galaxy. Extensive tests show that our method can measure w_p(r_p) in a statistically unbiased way. The accuracy of the measurement depends on the validity of the assumption in the method that the foreground/background galaxies are randomly distributed and thus uncorrelated with those galaxies of interest. Therefore, our method can be applied to the cases where foreground/background galaxies are distributed in large volumes, which is usually valid in real observations. We applied our method to data from SDSS including a sample of 10^5 LRGs at z~0.4 and a sample of about half a million galaxies at z~0.1, both of which are cross-correlated with a deep photometric sample drawn from the SDSS. On large scales, the relative bias factor of galaxies measured from w_p(r_p) at z~0.4 depends on luminosity in a manner similar to what is found at z~0.1, which are usually probed by autocorrelations of spectroscopic samples. On scales smaller than a few Mpc and at both z~0.4 and z~0.1, the photometric galaxies of different luminosities exhibit similar density profiles around spectroscopic galaxies at fixed luminosity and redshift. This provides clear support for the assumption commonly-adopted in HOD models that satellite galaxies of different luminosities are distributed in a similar way, following the dark matter distribution within their host halos.Comment: 38 pages, 12 figures, published in Ap

DEVELOPMENT AND TESTING OF THE BLANTON CLAMSHELL CLOSUREFOR USE ON RADIOACTIVE MATERIAL PACKAGING DRUMS

This paper provides a brief history of the U.S. Type B 6M specification container, its introduction into U.S. Code of federal regulations and its scheduled elimination three decades later. The paper also presents development, testing and deployment by the Department of Energy (DOE) of an enhanced drum closure called the 'Blanton Clamshell' (patent pending) that was designed to replace the standard open-head C-ring closure for the 55- and 85-gallon drums described in the 6M specification to extend their safe use. Nuclear Filter Technology has the Exclusive License for Clamshell production. Drum packages utilizing the standard C-ring closure have been a main-stay for over a half of a century in the national and international nuclear industry for shipping radioactive materials and will remain so in the foreseeable future. Drum package use in the U.S. increased heavily in the 1950's with development of the Weapons Complex and subsequently the commercial nuclear reactor industry

Physical Properties of Four SZE-Selected Galaxy Clusters in the Southern Cosmology Survey

We present the optical and X-ray properties of four clusters recently discovered by the South Pole Telescope (SPT) using the Sunyaev-Zel'dovich effect (SZE). The four clusters are located in one of the common survey areas of the southern sky that is also being targeted by the Atacama Cosmology Telescope (ACT) and imaged by the CTIO Blanco 4-m telescope. Based on publicly available griz optical images and XMM-Newton and ROSAT X-ray observations we analyse the physical properties of these clusters and obtain photometric redshifts, luminosities, richness and mass estimates. Each cluster contains a central elliptical whose luminosity is consistent with SDSS cluster studies. Our mass estimates are well above the nominal detection limit of SPT and ACT; the new SZE clusters are very likely massive systems with M>~5x10^14 M_sun.Comment: 5 pages, 2 figures. ApJL accepte

The Millennium Galaxy Catalogue: the space density and surface brightness distribution(s) of galaxies

We recover the joint and individual space density and surface brightness distribution(s) of galaxies from the Millennium Galaxy Catalogue. The MGC is a local survey spanning 30.9 sq deg and probing approximately one--two mag/sq arcsec deeper than either the Two-Degree Field Galaxy Redshift Survey (2dFGRS) or the Sloan Digital Sky Survey (SDSS). The MGC contains 10,095 galaxies to B_mgc < 20 mag with 96 per cent spectroscopic completeness. We implement a joint luminosity-surface brightness step-wise maximum likelihood method to recover the bivariate brightness distribution (BBD) inclusive of most selection effects. Integrating the BBD over surface brightness we recover the following Schechter function parameters: phi* = (0.0177 +/- 0.0015) h^3 Mpc^{-3}, M_{B}* - 5 log h = (-19.60 +/- 0.04) mag and alpha =-1.13 +/- 0.02. Compared to the 2dFGRS (Norberg et al 2002) we find a consistent M* value but a slightly flatter faint-end slope and a higher normalisation, resulting in a final luminosity density j_{b_J} = (1.99 +/- 0.17) x 10^8 h L_{odot} Mpc^{-3}. The MGC surface brightness distribution is a well bounded Gaussian at the M* point with phi* = (3.5 +/- 0.1) x 10^{-2} h^3 Mpc^{-3}, mu^{e*} = (21.90 +/- 0.01) mag/sq arcsec and sigma_{ln R_e} = 0.35 +/- 0.01. The characteristic surface brightness for luminous systems is invariant to M_{B} - 5 log h ~ -19 mag faintwards of which it moves to lower surface brightness. Higher resolution (FWHM 26 mag/sq arcsec in the B-band) observations of the local universe are now essential to probe to lower luminosity and lower surface brightness levels. [abridged]Comment: Accepted for publication in MNRAS, 26 pages with 21 figures (some degraded). A full pdf version, along with MGC data release, is available from the MGC website at, http://www.eso.org/~jliske/mg

Exploring the links between star formation and minor companions around isolated galaxies

Previous studies have shown that galaxies with minor companions exhibit an elevated star formation rate. We reverse this inquiry, constructing a volume-limited sample of \simL\star (Mr \leq -19.5 + 5 log h) galaxies from the Sloan Digital Sky Survey that are isolated with respect to other luminous galaxies. Cosmological simulations suggest that 99.8% of these galaxies are alone in their dark matter haloes with respect to other luminous galaxies. We search the area around these galaxies for photometric companions. Matching strongly star forming (EW(H{\alpha})\geq 35 \AA) and quiescent (EW(H{\alpha})< 35 \AA) samples for stellar mass and redshift using a Monte Carlo resampling technique, we demonstrate that rapidly star-forming galaxies are more likely to have photometric companions than other galaxies. The effect is relatively small; about 11% of quiescent, isolated galaxies have minor photometric companions at radii \leq 60 kpc h$^{-1}$ kpc while about 16% of strongly star-forming ones do. Though small, the cumulative difference in satellite counts between strongly star-forming and quiescent galaxies is highly statistically significant (PKS = 1.350 \times10$^{-3}$) out to to radii of \sim 100 h$^{-1}$ kpc. We discuss explanations for this excess, including the possibility that \sim 5% of strongly star-forming galaxies have star formation that is causally related to the presence of a minor companion.Comment: 7 pages, 6 figures, submitted to MNRA

Shoreward Intrusion of Upper Gulf Stream Water onto the United States Southeastern Continental Shelf

In winter, cooling of the South Atlantic Bight continental shelf water results in higher density in the middle shelf region relative to the shelf-break region where the western flank of the Gulf Stream flows. Shoreward, estuarine-like intrusion of the upper Gulf Stream water in the presence of such a positive onshore density gradient is then possible through advective processes triggered either by the meander of the Stream or onshore Ekman transports by southward wind stresses. Repeated cross-shelf hydrographic transects were conducted from 10 January through 30 January 1986 to more closely study this intrusion process. These observations show many features predicted by a previous numerical model study. A semi-empirical model is proposed here wherein the state of stratification of water on the outer continental shelf region just inshore of the shelf break is used as an indicator of the intrusion process. Model analysis suggests correlating the observed time rate of change of potential energy of the water column with wind-induced cross-shelf Ekman transport. The correlation fit is good for at least half of the data set, suggesting that wind-induced intrusion was significant during the observations. The analysis also suggests that it is possible to distinguish intrusion processes which are wind induced from those which are induced by Gulf Stream meanders. Both observations and the previous numerical model study show transient shelf-break upwelling following a southward wind impulse. A simplified model suggests that the upwelling is a result of a cyclonic vortex, bounded at the shelf break, produced by interaction of wind stress and sloping bottom topography. Transient upwellings introduce Gulf Stream water from below the mixed layer to the sea surface, where it is transported onshore to the continental shelf by intrusion processes. This provides a mechanism by which nutrient-rich, deeper Gulf Stream water can replenish the water mass of the adjacent continental shelf