Social Movements in Urban Society: The City as A Space of Politicization     

Byron Miller  Walter Nicholls 《Urban geography》2013,34(4):452-473

Recent anti-systemic social movements have illustrated the central role of cities in social movement mobilization. We not only highlight the characteristics of urban social relations that make cities fertile ground for mobilization, but also point to the disjunctures between the geographies and spatialities of social relations in the city, and the geographies and spatialities of many systemic processes. Struggles for a more just society must consider the broad geographies and spatialities of oppression, which we illustrate with a brief analysis of the Occupy movement. Finally, we introduce the next five articles in this special issue, all illustrating the importance of the geographies and spatialities of urban social struggle.  相似文献   

Properties of a Diffusive Hydrograph and the Interpretation of Its Single Parameter     

R. E. Criss  W. E. Winston 《Mathematical Geosciences》2008,40(3):313-325

The mathematical properties of the normalized diffusive hydrograph allow for easy determination of intrinsic basin characteristics. These include lag times between storm events and peak flow, recession rate, and the total, temporally integrated flow volume, all in terms of a single parameter, the basin time constant “b”. This simple function displays surprising fidelity to measured hydrographs of springs and hundreds of streams and small rivers. We explain this fidelity by showing that the curvature of the theoretical hydrograph matches that of the natural hydrographs better than several alternate models, and by demonstrating that the simple hydrograph function can be integrated over a range of time constants (0 to b _max) to represent the hierarchy of flow paths of varying lengths that exist in real watersheds. Surprisingly, the unwieldy analytical results from this integration are almost numerically indistinguishable from a simple hydrograph using a single, suitably-weighted average for the time constant. The peak flow times are shifted slightly. The accuracy with which the simple hydrograph approximates the integrated results for hierarchies of hydrographs representing individual flow paths explains why the former can realistically describe the discharge behaviors of complex natural watersheds.  相似文献   

中国浅成低温热液金矿床   总被引：2，自引：0，他引：2  

裘愉卓  涂光炽  Byron R. BERGER 《地球化学》2008,37(4)

浅成低温热液金矿床在中国传统上称为陆相火山岩型金矿床,主要发现在中国东部,后来在北疆地区也有新的发现.根据产出的大地构造背景,它们集中分布在3个带,并分属于3个成矿时期.它们包括:(1)新生代台湾东部岛弧带;(2)晚古生代北疆岛弧带;(3)中生代沿中朝克拉通北界的大陆边缘带;(4)中生代中国东南沿海地区的大陆边缘带.绝大多数矿床是低硫化型的,只有3个是高硫化型的,另有1个是与碱性岩系有关的Au-Te型矿床.除了中国最大的金矿床金瓜石矿床外,迄今为止中国大陆上的浅成低温热液金矿床总的来说只有较小的经济重要性.在中国东部发现的浅成低温热液金矿床的总储量,与区内广泛分布的中生代陆相火山岩十分巨大的体积极不相称.较古老的成矿年龄,中国东部的中生代和北疆的晚古生代,是中国大陆浅成低温热液金矿床的一个鲜明的特点.根据中国的成矿条件和保存条件的分析,以及与美国西部和俄国东部的对比,提出了中国浅成低温热液金矿床成矿潜力的一个初步评估.北疆可能有较大的寻找浅成低温热液金矿床的潜在重要性.  相似文献   

Annual cycle of radionuclide contamination on tide-washed pasture in the Mersey Estuary, NW England     

Michael S. Johnson  David Copplestone  Winston M. Fox  Steve R. Jones 《Estuaries and Coasts》2001,24(2):198-203

The radionuclide burden of vegetation comprising a tide-washed pasture at Ince Marsh in the Mersey Estuary, U.K., derives mainly from adhered external particulates originating as suspended sediments in estuarine water. Radionuclide concentrations are dominated by the growth cycle of the vegetation, with the highest winter levels of contamination activity an order of magnitude greater than the lowest levels in mid-summer. A secondary effect due to sediment transfer during periods of severe flooding produces subsidiary features on this dominant seasonal profile. Radionuclide concentrations on vegetation are in the range¹³⁷Cs=8–191,¹³⁴Cs=0.3–0.9,²⁴¹Am=0.6–46,²³⁸Pu=0.1–1.5, and^239/240Pu=0.8–44 Bq kg⁻¹. These ranges reflect the relative concentrations of radionuclides in estuarine sediment (¹³⁷Cs=615,²⁴¹Am=202, and^239/240Pu=104 Bq kg⁻¹) rather than the values in filtered estuary water (¹³⁷Cs=0.4,²⁴¹Am=0.001, and^239/240Pu=0.001 Bq 1⁻¹). Median K_d values for these radionuclide species are Cs=1,400, Am=200,000, and Pu=80,000 1 kg⁻¹).  相似文献   

Combination of TOPEX/POSEIDON data with a hydrographic inversion for determination of the oceanic general circulation and its relation to geoid accuracy   总被引：1，自引：0，他引：1  

Alexandre Ganachaud  Carl Wunsch  Myung-Chan Kim  Byron Tapley 《Geophysical Journal International》1997,128(3):708-722

A global estimate of the absolute oceanic general circulation from a geostrophic inversion of in situ hydrographic data is tested against and then combined with an estimate obtained from TOPEX/POSEIDON altimetric data and a geoid model computed using the JGM-3 gravity-field solution. Within the quantitative uncertainties of both the hydrographic inversion and the geoid estimate, the two estimates derived by very different methods are consistent. When the in situ inversion is combined with the altimetry/geoid scheme using a recursive inverse procedure, a new solution, fully consistent with both hydrography and altimetry, is found. There is, however, little reduction in the uncertainties of the calculated ocean circulation and its mass and heat fluxes because the best available geoid estimate remains noisy relative to the purely oceano-graphic inferences. The conclusion drawn from this is that the comparatively large errors present in the existing geoid models now limit the ability of satellite altimeter data to improve directly the general ocean circulation models derived from in situ measurements. Because improvements in the geoid could be realized through a dedicated spaceborne gravity recovery mission, the impact of hypothetical much better, future geoid estimates on the circulation uncertainty is also quantified, showing significant hypothetical reductions in the uncertainties of oceanic transport calculations, Full ocean general circulation models could better exploit both existing oceanographic data and future gravity-mission data, but their present use is severely limited by the inability to quantify their error budgets.  相似文献   

The role of oxyradicals in intracellular proteolysis and toxicity in mussels     

Miles A. Kirchin  Michael N. Moore  Roger T. Dean  Gary W. Winston 《Marine environmental research》1992,34(1-4)

Studies were performed on the common mussel, M. edulis L., to determine whether copper (Cu) exposure can affect the extent to which digestive cell proteins are oxidised and whether such oxidative damage is mediated by free radicals. Three age groups of mussels were exposed for 6 ^-days to environmentally realistic concentrations of Cu and then digestive gland homogenates were examined for evidence of protein carbonyl formation. Significant increases in carbonyls relative to untreated control mussels were seen for the youngest (2–4 year-old) and oldest (≥ 10 year-old) mussels only after exposure for 6 days, followed by recovery from exposure for a further 6 days. Untreated mussels also showed an age-related difference in protein oxidation, with a significantly lower concentration in the youngest animals (2–4 year olds). Copper did not affect the levels of modified tryptophan or tyrosine residues or the extent of total lipid peroxidation in digestive gland homogenate. Significant depletion of total vitamin E (a-tocopherol) was seen only in young and medium-aged mussels following exposure for 6 days. The levels of protein carbonyl groups were increased in digestive cell cytosol and lighter lysosomes but not in heavier lysosomes or digestive gland microsomes following 5 days exposure to Cu. Dihydrohodamine-123 was converted to fluorescent rhodamine-123 following sequestration into digestive cell lysosomes. The results suggest a link between the lysosomal sequestration of copper, a concomitant increase in the production of oxyradicals and the potential for intracellular oxidative damage, as well as an increased capacity for oxidative damage in older animals.  相似文献   

High-frequency signal and noise estimates of CSR GRACE RL04     

Jennifer A. Bonin  Srinivas Bettadpur  Byron D. Tapley 《Journal of Geodesy》2012,86(12):1165-1177

A sliding window technique is used to create daily-sampled Gravity Recovery and Climate Experiment (GRACE) solutions with the same background processing as the official CSR RL04 monthly series. By estimating over shorter time spans, more frequent solutions are made using uncorrelated data, allowing for higher frequency resolution in addition to daily sampling. Using these data sets, high-frequency GRACE errors are computed using two different techniques: assuming the GRACE high-frequency signal in a quiet area of the ocean is the true error, and computing the variance of differences between multiple high-frequency GRACE series from different centers. While the signal-to-noise ratios prove to be sufficiently high for confidence at annual and lower frequencies, at frequencies above 3 cycles/year the signal-to-noise ratios in the large hydrological basins looked at here are near 1.0. Comparisons with the GLDAS hydrological model and high frequency GRACE series developed at other centers confirm CSR GRACE RL04’s poor ability to accurately and reliably measure hydrological signal above 3–9 cycles/year, due to the low power of the large-scale hydrological signal typical at those frequencies compared to the GRACE errors.  相似文献   

Desert heat island study in winter by mobile transect and remote sensing techniques   总被引：1，自引：0，他引：1  

Chen-Yi Sun  Anthony J. Brazel  Winston T. L. Chow  Brent C. Hedquist  Lela Prashad 《Theoretical and Applied Climatology》2009,98(3-4):323-335

A familiar problem in urban environments is the urban heat island (UHI), which potentially increases air conditioning demands, raise pollution levels, and could modify precipitation patterns. The magnitude and pattern of UHI effects have been major concerns of a lot of urban environment studies. Typically, research on UHI magnitudes in arid regions (such as Phoenix, AZ, USA) focuses on summer. UHI magnitudes in Phoenix (more than three million population) attain values in excess of 5°C. This study investigated the early winter period—a time when summer potential evapotranspiration >250 mm has diminished to <90 mm. An analysis of the winter magnitude of the heat island in Phoenix has been studied very little, and therefore with the aid of automobile transects, fixed stations, and remote sensing techniques, we investigated a portion of the large Phoenix metropolitan area known as the East Valley. The eastern fringes of the metropolitan area abut against breaks in sloping terrain. The highest UHI intensity observed was >8.0°C, comparable to summertime UHI conditions. Through analysis of the Oke (1998) weather factor Φ_W, it was determined thermally induced nighttime cool drainage winds could account for inflating the UHI magnitude in winter.  相似文献   

The CQU Regional Seismic Network and applications to underground mining in Central Queensland,Australia     

Byron McKavanagh  Bruce Boreham  Kevin McCue  Gary Gibson  Jennifer Hafner  George Klenowski 《Pure and Applied Geophysics》1995,144(1):39-57

Digital seismograms continuously recorded from 1988 to 1992 by two stations of the RESNOM seismic network in northern Baja California, Mexico, were used to search for probable shear-wave anisotropic characteristics in the region of the Cerro Prieto fault. Shear-wave splitting was identified in many of the three-component records analyzed. We measured the polarization direction of the leadingS wave inside theS-wave window as well as the delay times between fast and slow phases on those records displaying shear-wave splitting. For station CPX, which is nearest the Imperial Valley region to the north, the preferred polarization direction found in this study (azimuth 180°±10°) coincides with the direction of the regional maximum compressive stress determined for the region. This polarization direction can be interpreted in terms of the “Extensive Dilatancy Anisotropy” model as the effect of vertical parallel aligned cracks. The preferred polarization direction measured at LMX, however, gives an azimuth of 45°±5°. Thus, it appears that faults and fractures aligned oblique to the main tectonic trend have a greater influence on the anisotropic characteristics of the crust south of Cerro Prieto volcano than that of the regional stress field. Time delays between slow and fastS waves observed at CPX appear constant from 1988 to 1992 while delays measured at LMX for the same interval indicate a small increase with time which cannot be attributed to azimuthal variations of paths.  相似文献   

Theoretical aspects of coal washer performance     

Stanislaw Cierpisz  Byron S. Gottfried 《International Journal of Mineral Processing》1977,4(3):261-278

This paper presents a theoretical analysis of the performance of ideal float-and-sink type coal washing devices. Included are studies of single washer performance, single washer with bypass, multiple washers in parallel and multiple washers in series. A maximum yield principle is developed for the cases of a single washer with bypass and multiple washers in parallel. The results of numerical calculations for actual washers are also presented and compared with the theoretical predictions for multiple washers in parallel and multiple washers in series.  相似文献