Nekton falls, low-intensity disturbance and community structure of infaunal benthos in the deep sea

A simulation of natural disturbance at the bathyal seafloor evoked rapid response from dominant infaunal species, for the first time providing experimental evidence that similar disturbances structure normal deep-sea communities. Parcels of dead fish (1–40 kg) were placed on the seafloor at a depth of 1310 m in the Santa Catalina Basin and monitored with Alvin and free-vehicle cameras for up to 8 wk. Dense aggregations of fish and ophiuroids were rapidly attracted to the baitfalls; in the process of consuming the bait, these megafaunal scavengers disrupted sediment surface structures and resuspended substantial amounts of sediment. The predominant macrofaunal effect was reduction of infaunal species diversity and community abundance around treatments. The most strongly depressed species was the community dominant Tharyx monilaris, a near-surface-dwelling cirratulid polychaete. Disturbance effects were low in intensity, however, with a large number of background species persisting within the perturbed area. Three macrofaunal species rapidly colonized the areas of disturbance/enrichment near baitfalls; two of these species, the paraonid polychaete Levinsenia oculata and the cirratulid polychaete Chaetozone sp. A, were dominant members of the surrounding community, while the third respondent, the cumacean (?)Cumella sp. A, was rare in background sediments. L. oculata and (?)Cumella apparently responded as post-larvae, suggesting that adult colonization of disturbed habitats may be important in deep-sea environments. The opportunistic response of two common species indicates that normal components of the Santa Catalina Basin fauna can rapidly exploit disequilibrium conditions, such as those resulting from a variety of low-intensity disturbance sources (e.g., conveyor-belt species, megafaunal croppers , skates, flatfish, carcasses of megafauna, kelp falls) commonly observed at the basin floor. Low-intensity disturbance may thus contribute materially to the structure of this, and other, deep-sea communities

Report of the direct infrared sensors panel

The direct infrared sensors panel considered a wide range of options for technologies relevant to the science goals of the Astrotech 21 mission set. Among the technologies assessed are: large format arrays; photon counting detectors; higher temperature 1 to 10 micro-m arrays; impurity band conduction (IBC) or blocked impurity band (BIB) detectors; readout electronics; and adapting the Space Infrared Telescope Facility and Hubble Space Telescope. Detailed development plans were presented for each of these technology areas

Case-control study of arsenic in drinking water and lung cancer in California and Nevada.

Millions of people are exposed to arsenic in drinking water, which at high concentrations is known to cause lung cancer in humans. At lower concentrations, the risks are unknown. We enrolled 196 lung cancer cases and 359 controls matched on age and gender from western Nevada and Kings County, California in 2002-2005. After adjusting for age, sex, education, smoking and occupational exposures, odds ratios for arsenic concentrations ≥85 µg/L (median = 110 µg/L, mean = 173 µg/L, maximum = 1,460 µg/L) more than 40 years before enrollment were 1.39 (95% CI = 0.55-3.53) in all subjects and 1.61 (95% CI = 0.59-4.38) in smokers. Although odds ratios were greater than 1.0, these increases may have been due to chance given the small number of subjects exposed more than 40 years before enrollment. This study, designed before research in Chile suggested arsenic-related cancer latencies of 40 years or more, illustrates the enormous sample sizes needed to identify arsenic-related health effects in low-exposure countries with mobile populations like the U.S. Nonetheless, our findings suggest that concentrations near 100 µg/L are not associated with markedly high relative risks

An Extraordinary Scattered Broad Emission Line in a Type 2 QSO

An infrared-selected, narrow-line QSO has been found to exhibit an extraordinarily broad Halpha emission line in polarized light. Both the extreme width (35,000 km/sec full-width at zero intensity) and 3,000 km/sec redshift of the line centroid with respect to the systemic velocity suggest emission in a deep gravitational potential. An extremely red polarized continuum and partial scattering of the narrow lines at a position angle common to the broad-line emission imply extensive obscuration, with few unimpeded lines of sight to the nucleus.Comment: 4 pages, 1 figure, to appear in the Astrophysical Journal Letter

USCID fourth international conference

Presented at the Role of irrigation and drainage in a sustainable future: USCID fourth international conference on irrigation and drainage on October 3-6, 2007 in Sacramento, California.Includes bibliographical references.The South County Regional Wastewater Authority (SCRWA) delivers recycled water to local farmers, golf courses and parks throughout the City of Gilroy, California, located approximately 30 miles south of San Jose, California. The SCRWA recently completed an expansion to the tertiary treatment system, which included additional tertiary filter banks, a new storage reservoir, additional pumping capacity, and a new delivery pipe with turnouts. With the new facilities on-line, the SCRWA recycled water system consists of 6 million gallons per day of firm tertiary filtration capacity, one on-site recycled water storage reservoirs with a total of 3 million gallons of storage, two recycled water delivery pipelines, and four pumping stations. The new 3 MG reservoir and additional pumping stations at the SCRWA treatment plant are critical in meeting the peak demands of agricultural irrigation. The reservoir enables the treatment plant operators to shave demand peaks and provides the flexibility for the SCRWA to shut down tertiary filters as needed. Having 6 MGD of firm tertiary filter capacity gives the SCRWA the capability of producing enough recycled water to meet existing and future demands. Interest among potential agricultural recycled water users in the Valley is growing as the price for recycled water becomes competitive with the price of pumping groundwater in the area. Farmers see recycled water as an economical and reliable source for crop irrigation. The SCRWA recycled water system has proven to be an excellent source of high quality water for irrigation of farmlands

A metapopulation model for whale-fall specialists: The largest whales are essential to prevent species extinctions

The sunken carcasses of great whales (i.e., whale falls) provide an important deep-sea habitat for more than 100 species that may be considered whale-fall specialists. Commercial whaling has reduced the abundance and size of whales, and thus whale-fall habitats, as great whales were hunted and removed from the oceans, often to near extinction. In this article, we use a metapopulation modeling approach to explore the consequences of whaling to the abundance and persistence of whale-fall habitats in the deep sea and to the potential for extinction of whale-fall specialists. Our modeling indicates that the persistence of metapopulations of whale-fall specialists is linearly related to the abundance of whales, and extremely sensitive (to the fourth power) to the mean size of whales. Thus, whaling-induced declines in the mean size of whales are likely to have been as important as declines in whale abundance to extinction pressure on whale-fall specialists. Our modeling also indicates that commercial whaling, even under proposed sustainable yield scenarios, has the potential to yield substantial extinction of whale-fall specialists. The loss of whale-fall habitat is likely to have had the greatest impact on the diversity of whale-fall specialists in areas where whales have been hunted for centuries, allowing extinctions to proceed to completion. The North Atlantic experienced dramatic declines, and even extirpation, of many whale species before the 20th century; thus, extinctions of whale-fall specialists are likely to have already occurred in this region. Whale depletions have occurred more recently in the Southern Hemisphere and across most of the North Pacific; thus, these regions may still have substantial extinction debts, and many extant whale-fall specialists may be destined for extinction if whale populations do not recover in abundance and mean size over the next few decades. Prior to the resumption of commercial whaling, or the loosening of protections to reduce incidental take, the impacts of hunting on deep-sea whale-fall ecosystems, as well as differential protection of the largest whales within and across species, should be carefully considered

The ferroelectric transition in YMnO3_3 from first principles

We have studied the structural phase transition of multiferroic YMnO$_3$ from first principles. Using group-theoretical analysis and first-principles density functional calculations of the total energy and phonons, we perform a systematic study of the energy surface around the prototypic phase. We find a single instability at the zone-boundary which couples strongly to the polarization. This coupling is the mechanism that allows multiferroicity in this class of materials. Our results imply that YMnO$_3$ is an improper ferroelectric. We suggest further experiments to clarify this point.Comment: published version, PRB (rapid comm), slight change in presentatio