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831.
The spatial variation of racisms is an under-researched field of inquiry, certainly in Australia. This paper explores the geographies of racism in New South Wales. Responses to three opinion polls conducted between 1994 and 1996 were used to construct patterns of racisms across NSW. Preliminary findings suggest a substantive degree of racism in NSW. There was little evidence of an urban-rural variation in terms of ethnocentrism. Examination of regional variations confounds this simple division. Social Constructionist theory is put forward as a spatially sensitive theory for understanding and responding to the geographies of racism. The identification of regional variations in racism is crucial to the development of regionally specific anti-racism campaigns. This paper highlights the need for more comprehensive analyses of the varying causes and remedies for racisms. 相似文献
832.
The salt marsh periwinkleLittoraria irrorata (Say) remains on the substratum during low tide but climbs above the water on stalks ofSpartina alterniflora Loisel during high tide. Rhythmic tidal migrations may allowL. irrorata to avoid predators such as blue crabsCallinectes sapidus Rathbun that forage when the marsh is inundated. These tidal rhythms may be driven by endogenous clocks or they may be easily entrained. Snails with flexible and entrainable climbing rhythms may be able to avoid predators in unpredictable environments (e.g., when water unexpectedly covers the substratum as in storm surges). We tested the behavioral response ofL. irrorata to different simulated tidal regimes in the laboratory, and the effect of remaining above mean high water (MHW) on snail survivorship in a smallS. alterniflora salt marsh. In laboratory mesocosms, vertical snail position was measured under constant water levels, simulated tidal cycles, and simulated tidal cycles 180° out of phase (reversed). Under constant water levels, snails ceased to migrate vertically after 1 d. When exposed to tidal and reversed tidal cycles, snails migrated in synchrony with the appropriate simulated rhythm.L. irrorata entrained quickly to differing tidal cycles and maintained their position above the water surfce when water levels were high. In a field experiment, snails were tethered toS. alteriflora plants near the substratum and above MHW in the marsh for 1 wk to assess survival. Survival of snails tethered above MHW was sigificantly greater than for snails tethered at the base of plants; no snails in control cages died. Rapid alteration of tidal vertical migrations may allowL. irrorata to avoid predators that forage when water inundates the marsh predictably or unexpectedly. 相似文献
833.
An index was developed for estuarine macrobenthos in the Gulf of Mexico that discriminated between areas with degraded environmental conditions and areas with undegraded or reference conditions. Test sites were identified as degraded or reference based on criteria for dissolved oxygen levels, sediment toxicity tests, and sediment contamination. Discriminant analysis was used to identify a suite of measures of benthic community composition and diversity that would most successfully distinguish degraded from undegraded sites. The resultant benthic index was composed of a linear combination of three factors: the Shannon-Wiener diversity index, the proportion of total benthic abundance as tubificid oligochaetes, and the proportion of total benthic abundance as bivalve molluscs. This index was used to evaluate the spatial patterns of degraded benthic resources in the Gulf of Mexico. 相似文献
834.
This paper presents an analysis of a neglected area of study by geographers; that of resident action groups. During the 1980s there has been a significant increase in the number of resident action groups throughout Sydney. Resident activism has influenced local planning processes, the location of noxious facilities and subsequent urban form. This has initiated important reactions by government at both the local and State levels. Urban collective activisms have been hypothesised as single‐issue, self‐serving nimby groups. However, RAGs are also empowering forces, in which women and men are introduced to the political structures and become engaged in protest and resistance that can challenge the social and spatial order. RAGs can, either singularly or cumulatively, force a re‐aligning of existing power relations, and they can necessitate changed modes of governance (or govern‐mentality). 相似文献
835.
836.
837.
A remarkably regular cyclicity with a fundamental period of ~11–12 cycles is preserved in the 680 million year old Elatina formation of South Australia. All but one of the many periods present can be interpreted as resulting from the combined influences of the sunspot cycle and the lunar nodal tide - in particular, beating between these two cycles gives rise to a long period phase alternation. Available paleontological evidence is used to constrain the lunar distance 680 Ma ago, thereby constraining the length of the lunar nodal tide. We then infer from the beat period that the sunspot cycle was 10.8 ± 0.2 years, which is in agreement with independent astronomical evidence suggesting that the sunspot cycle would then have been some 3–10% shorter than it is at present. Although this interpretation is not consistent with the 12.0 year sunspot cycle counted by Williams and Sonett (1985), we demonstrate that unavoidable random errors made in discriminating unusually indistinct varves gives rise to a systematic overcount of varves of this magnitude. The clarity of this evidence for solar and lunar signals in the climate 680 Ma ago lends support to reports of their importance today.National Research Council Postoctoral Associate. 相似文献
838.
During two years of sampling, 747 larval and 1,379 juvenile spotted seatrout,Cynoscion nebulosus, were collected in Tampa Bay, Florida; 93% were less than 75 mm SL. Length-frequency distributions and otolith analysis showed that spawning took place from early April until late October. Two seasonal spawning peaks (spring and summer) were made up of many smaller peaks, apparently timed with moon phases. Plankton samples contained larvae that measured up to about 7 mm SL (17 d old). Larvae collected from an upper bay station were less numerous and larger than those collected at other stations. The presence of small larvae from middle and lower bay stations indicated that spawning probably took place from the middle bay to nearshore Gulf waters. Juveniles used seagrass beds as their major habitat, but they were also found in unvegetated backwaters. Spotted seatrout grew to about 35 mm SL in 2 months, 84 mm SL in 4 months, and 140 mm SL in 6 months. Eighty-five percent of the alimentary tracts in larvae were empty; those with food contained primarily copepods. Eleven percent of the stomachs of juveniles were empty. Fish and shrimp were the most important food groups in the diets of fish >15 mm SL. Intraspecific comparisons of diets showed high dietary overlap between larval fish and those measuring 8–15 mm SL and among size classes >15 mm SL. 相似文献
839.
840.
The errors in the chemical analyses of a granodiorite rock powder for 6 constituents (K 2O, Na2O, CaO,∑Fe2O3, MgO, and MnO) have been determined by replicate analyses of the whole rock and of a series of different sieved fractions. Sample inhomogeneity is indicated. This is confirmed by analyses of the fused rock powder. Fusion to a glass is therefore recommended for the preparation of geochemical rock standards. 相似文献