Morphology and surface brightness evolution of z∼1.1 radio galaxies

We use K '-band (2.1-μm) imaging to investigate the angular size and morphology of 10 6C radio galaxies, at redshifts 1≤ z ≤1.4. Two radio galaxies appear to be undergoing mergers, another contains, within a single envelope, two intensity peaks aligned with the radio jets, while the other seven appear consistent with being normal ellipticals in the K band.
Intrinsic half-light radii are estimated from the areas of each radio galaxy image above a series of thresholds. The 6C galaxy radii are found to be significantly smaller than those of the more radio-luminous 3CR galaxies at similar redshifts. This would indicate that the higher mean K -band luminosity of the 3CR galaxies reflects a difference in the size of the host galaxies, and not solely a difference in the power of the active nuclei.
The size–luminosity relation of the z ∼1.1 6C galaxies indicates a 1.0–1.6 mag enhancement of their rest frame R -band surface brightness relative to either local ellipticals of the same size or FRII radio galaxies at z <0.2. The 3CR galaxies at z ∼1.1 show a comparable enhancement in surface brightness. The mean radius of the 6C galaxies suggests that they evolve into ellipticals of L ∼ L * luminosity, and is consistent with their low-redshift counterparts being relatively small FRII galaxies ∼25 times lower in radio luminosity, or small FRI galaxies ∼1000 times lower in radio luminosity. Hence the 6C radio galaxies appear to undergo as much optical and radio evolution as the 3CR galaxies.     

Response of resource excavations in Mobile Bay, Alabama, to extreme forcing

Fossil reef deposits of the American oyster,Crassostrea virginica, are a common component of the near surface sediments in the middle and upper reaches of Mobile Bay, northern Gulf of Mexico. Mining of these deposits occurred from 1946 through 1982 in open areas of undisturbed bay bottom, outside of the shipping channel corridors, in water depths of 3–5 m. The mining process resulted in the formation of pit to furrow-shaped depressions with elevated rims at some sites and troughs and ridges in other areas. Studies carried out in the early 1970s predicted normal physical processes would restore the bottom to pre-shell mining conditions within 1 yr, thus minimizing any long-term effects on the Mobile Bay estuary. However, over the period 1974–1976 unfilled excavations, some with raised rims and ridges, were observed where mining had occurred 3–5 yr earlier. In addition, the depressions tended to be sites of relatively high salinity, hypoxic to anoxic water. In 1992–1993, close grid bathymetric surveys produced no indication of either depressions or raised features at any of the old mining sites. Evidence suggests this leveling of the bay’s bathymetry was the result of two major hurricanes, Frederic in 1979 and Elena in 1985, which mobilized and redistributed significant quantities of sediments within Mobile Bay. These findings indicate currents and waves associated with Mobile Bay’s normal tidal activity and annual recurrent storms were acting very slowly to refill depressions and flatten elevated features. In contrast, the direct impact of major hurricanes appears to have served as an effetive agent to return Mobile Bay’s bathymetry to a state similar to pre-shell mining conditions.     

Drought Monitoring Using Data Mining Techniques: A Case Study for Nebraska, USA

Drought has an impact on many aspects of society. To help decision makers reduce the impacts of drought, it is important to improve our understanding of the characteristics and relationships of atmospheric and oceanic parameters that cause drought. In this study, the use of data mining techniques is introduced to find associations between drought and several oceanic and climatic indices that could help users in making knowledgeable decisions about drought responses before the drought actually occurs. Data mining techniques enable users to search for hidden patterns and find association rules for target data sets such as drought episodes. These techniques have been used for commercial applications, medical research, and telecommunications, but not for drought. In this study, two time-series data mining algorithms are used in Nebraska to illustrate the identification of the relationships between oceanic parameters and drought indices. The algorithms provide flexibility in time-series analyses and identify drought episodes separate from normal and wet conditions, and find relationships between drought and oceanic indices in a manner different from the traditional statistical associations. The drought episodes were determined based on the Standardized Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI). Associations were observed between drought episodes and oceanic and atmospheric indices that include the Southern Oscillation Index (SOI), the Multivariate ENSO Index (MEI), the Pacific/North American (PNA) index, the North Atlantic Oscillation (NAO) Index, and the Pacific Decadal Oscillation (PDO) Index. The experimental results showed that among these indices, the SOI, MEI, and PDO have relatively stronger relationships with drought episodes over selected stations in Nebraska. Moreover, the study suggests that data mining techniques can help us to monitor drought using oceanic indices as a precursor of drought.     

Recent protected-area designation in China: an evaluation of administrative and statutory procedures

Past protected-area (PA) designation in China followed a centralized administrative approach with minimum participation of lower-echelon governments. A period of deregulation and decentralization in 1979–91 without the benefit of relevant legislation resulted in few designations and poor management. Responding to national and international encouragement to augment the conservation of natural resources, the central government enacted statutory procedures in 1991 to encourage and regulate PA establishments at different administrative levels of government. The study evaluates the effectiveness of the new procedures in fulfilling conservation objectives. The new legislative and administrative regime reinforces deregulation and decentralization by devolving designation power and shifting financial and management responsibilities to lower levels of government, and involving more scientists and objective site assessment in PA design and assessment. Problems have arisen in the designation process due to the omission of key biota and ecosystems, bypassing the scientific assessment stage, too much emphasis on non-conservation gains, ignoring the needs of local communities, escalating people–park conflicts, intensifying paper-park syndrome, and the conflicting role of experts. The recently designated Shimentai Provincial Rank Nature Reserve in a mountain area in south China served as a case study to illustrate the procedures and problems.     

A numerical modelling study of coastal flooding

Summary A coastal ocean model capable of modelling tides, storm surge and the overland flow of floodwaters has been further developed to include the flux of water from tributaries and the forcing from wave breaking that leads to wave setup in the nearshore zone. The model is set up over the Gold Coast Broadwater on the east coast of Australia. This complex region features a coastal lagoon into which five tributaries flow and is subject to flooding from extreme oceanic conditions such as storm surge and wave setup as well as terrestrial runoff. Weather conditions responsible for storm surge, waves and flooding include cyclones of both tropical and mid-latitude origin. Two events are modelled. The first is an east coast low event that occurred in April 1989. This event verified well against available observations and analysis of the model simulations revealed that wave setup produced a greater contribution to the elevated water levels than the storm surge. The second case to be modelled was tropical cyclone Wanda, responsible for the 1974 floods. Modelled water levels in the Broadwater were reasonably well captured. Sensitivity experiments showed that storm surge and wave setup were only minor contributors to the elevated sea levels and their contribution was confined to the earlier stage of the event before the runoff reached its peak. The contribution due solely to runoff exhibited a tidal-like oscillation that was 180° out-of-phase with the tide and this was attributed to the greater hydraulic resistance that occurs at high tide. A simulation of this event with present day bathymetry at the Seaway produced sea levels that were 0.3–0.4 m lower than the simulation with 1974 bathymetry highlighting the effectiveness of deepened Seaway channel to reduce the impact of severe runoff events in the Broadwater. Received October 16, 2001 Revised December 28, 2001     

Genetic variation in two populations of blue crab,Callinectes sapidus

Genetic variability of the blue crab,Callinectes sapidus, was estimated for populations in Chesapeake and Chincoteague Bays. Genetic similarity between these populations was attributed to larval intermixing in the mid-Atlantic Bight.