852 resultados para Sinnissippi Dam (Rock Falls, Ill.)


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Orange, green, red, black pencil on tracing papter. Location, type of plantings; notes. Unsigned. 58 cm. x 84 cm. Scale: 1"=20' [from photographic copy by Lance Burgharrdt]

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Norway, Mich.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

verso: Sitting or squatting Spaulding, McGregor, Griffin & Orr. Back-Hale Smith in middle. Starved Rock-1948?

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Alternations between siliciclastic, carbonate and evaporitic sedimentary systems, as recorded in the Aptian mixed succession of southern Tunisia, reflect profound palaeoceanographic and palaeoclimatic changes in this area of the southern Tethyan margin. The evolution from Urgonian-type carbonates (Berrani Formation, lower Aptian) at the base of the series, to intervals dominated by gypsum or detrital deposits in the remainder of the Aptian is thought to result from the interplay between climate change and tectonic activity that affected North Africa. Based on the evolution of clay mineral assemblages, the early Aptian is interpreted as having been dominated by slightly humid conditions, since smectitic minerals are observed. Near the early to late Aptian boundary, the onset of a gypsiferous sedimentation is associated with the appearance of palygorskite and sepiolite, which supports the installation of arid conditions in this area of the southern Tethyan margin. The evaporitic sedimentation may have also been promoted by the peculiar tectonic setting of the Bir Oum Ali area during the Aptian, where local subsidence may have been tectonically enhanced linked to the opening of northern and central Atlantic. Stress associated with the west and central African rift systems may have triggered the development of NW-SE, hemi-graben structures. Uplifted areas may have constituted potential new sources for clastic material that has been subsequently deposited during the late Aptian. Chemostratigraphic (d13C) correlation of the Bir Oum Ali succession with other peri-Tethyan regions complements biostratigraphic findings, and indicates that a potential expression of the Oceanic Anoxic Event (OAE) 1a may be preserved in this area of Tunisia. Although the characteristic negative spike at the base of this event is not recognized in the present study, a subsequent, large positive excursion with d13C values is of similar amplitude and absolute values to that reported from other peri-Tethyan regions, thus supporting the identification of isotopic segments C4-C7 of the OAE1a. The absence of the negative spike may be linked to either non preservation or non deposition: the OAE1a occurred in a global transgressive context, and since the Bir Oum Ali region was located in the innermost part of the southern Tethyan margin during most of the Aptian, stratigraphic hiatuses may have been longer than in other regions of the Tethys. This emphasizes the importance of integrating several stratigraphic disciplines (bio-, chemo- and sequence stratigraphy) when performing long-distance correlation.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Along the N-S-transect of DSDP-Sites 5446, 397, 141, and 366, oxygen and carbon isotopes, flux rates of calcium carbonate, terrigenous matter, and biogenic opal, clay minerals and the size distribution of terrigenous partictes were determined in order to assess the ties between atmospheric and oceanic surface and deep-water circulation off northwest Africa during the late Neogene. During the last 9 m.y., both the paleoceanography in the eastern Atlantic and west African paleodimates were intimately correlated with the evolution of the polar ice sheets as reflected in the benthos d18O curves of the 4 DSDP-Sites. These records make it possible to distinguish six major time intervals which were charaterized by long-term persistent regimes of climatic stability or climatic change. Short-term, "Milankovitch"-type cycles superimpose the long-term climatic evolution and may reflect the chronostratigraphic control fluctuations of the solar insolation persisting back to pre-Pleistocene times. Relatively stable, warm climates prevailed during the late Tortonian/early Messinean, 9 to 6 m.y., and the early Pliocene, 4.5 to 3.5 m.y. ago. Based on d18O curves, the amplitudes of short-term climatic variation were generally low, and the ice sheets were smaller than during peak Holocene time. Oceanic circulation and resulting paleoproductivity in upwelling zones were insignificant. The strength of dust supplying meridional trade winds was low (3 to 5 m/s), interglacial-style zonal winds near the ITCZ were dominant, as indicated by the high abundance of kaolinite. Phases of fluvial sediment supply were common. Humidity was characteristic of the climate in northwest Africa for the major part of this time. Major episodes of climatic deterioration in the subtropics occurred in the latest Miocene/early Pliocene, between some 5.6 and 5.2 and between 4.9 and 4.6 m.y. ago, in the late Pliocene, between 3.2 and 2.4 m.y. ago, and again in the Quaternary, near 1 m.y. ago. The episodes were correlated with marked increases of the global ice volume, as revealed by drastic increases of d18O values. They suggest sea-level falls of up to 70 m below the present sea level in the latest Miocene and earliest Pliocene and of 145 m in the latest Pliocene and Quaternary. The climatic changes resulted in strongly enhanced meridional trade winds as suggested by coarser terrigenous grain-sizes, increased mass accumulation rates of eolian dust, and changes in clay-mineral composition from dominantly kaolinite to illite and chlorite. The meridional trade winds reached speeds of 8 to 10 m/s with a maximum near 15 m/s. The enhanced winds probably led t o intensified coastal upwelling as shown by the contemporaneous local increase i n the deposition of biogenic silica and the local depletion of 13C at Site 397. The most drastic environmental changes near 2.4 and 1 m.y. ago coincide with hiatuses which may indicate phases of general erosion due to strongly enhanced deep-water circulation in the northeast At1antic along the northwest African continental margin. The occasional occurrence of quartz grains coarser than 250 µm may suggest ice-rafted debris in sediments off Morocco. During these time intervals the climate in NW-Africa was dominantly arid. Nevertheless, fluvial runoff (and humidity) continued to be important during intermittent warm phases of the short-term climatic cycles. During the end and the beginning of (inter-) glacial times, fluvial supply of nutrients seems to be the dominant factor, controling phases of enhanced paleoproductivity observed off northwest Africa, whereas during phases of glacial maximum strenger fertility of (increased) coastal upwelling becomes more important. A long-term evolution of paleoenvironments during the last 40 m.y. is depicted in the sediments of Site 366 and is clearly controlled by the plate tectonic route of this Site. During Oligocene times, Site 366 lay in the center of the equatorial upwelling, as shown by the high content of biogenic silica contributing up to 100 % of the carbonate-free sediment fraction >6 µm. The influence of equatorial upwelling abruptly terminated near 15 m.y. ago, a change in the record exaggerated by a hiatus of about 2 m.y. Prior to 25 m.y., the terrigenous input at the paleolatitude of Site 366 was restricted t o eolian sediment supply from South Africa by southeasterly trade winds, as shown by dominantly illite and chlorite in the clay fraction and extremely fine-grained terrigenous matter. Near the Oligocene/Miocene boundary, Site 366 drifted across the equator into the belt of the northeasterly trade winds, which is inferred from the increased content of kaolinite and coarser grain sizes of the terrigenous sediment fraction. The clay-mineral and grain-size compositions of Site 366 do not reflect a noteworthy northward shift of the ITCZ during late Miocene and early Pliocene times, i.e. no marked global circulation asymmetry due to the possible absence of a major Northern Hemisphere glaciation (Flohn 1981). This lack of a more northerly position of the ITCZ may result from a bipolar glaciation already existing during late Miocene times, such as also suggested by the evidence of tillites on Iceland and in southern Alaska during those intervals (e.g., Denton & Amstrong 1969, Mudie & Helgason 1983).

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Panel title.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The influence of particles recycling on the geochemistry of sediments in a large tropical dam lake in the Amazonian region, Brazil. Article in Journal of South American Earth Sciences 72 · December 2016 DOI: 10.1016/j.jsames.2016.09.012 1st Rita Fonseca 16.85 · Universidade de Évora 2nd Catarina Pinho 3rd Manuela Oliveira 22.6 · Universidade de Évora Abstract As a result of over-erosion of soils, the fine particles, which contain the majority of nutrients, are easily washed away from soils, which become deficient in a host of components, accumulating in lakes. On one hand, the accumulation of nutrients-rich sediments are a problem, as they affect the quality of the overlying water and decrease the water storage capacity of the system; on the other hand, sediments may constitute an important resource, as they are often extremely rich in organic and inorganic nutrients in readily available forms. In the framework of an extensive work on the use of rock related materials to enhance the fertility of impoverish soils, this study aimed to evaluate the role on the nutrients cycle, of particles recycling processes from the watershed to the bottom of a large dam reservoir, at a wet tropical region under high weathering conditions. The study focus on the mineralogical transformations that clay particles undergo from the soils of the drainage basin to their final deposition within the reservoir and their influence in terms of the geochemical characteristics of sediments. We studied the bottom sediments that accumulate in two distinct seasonal periods in Tucuruí reservoir, located in the Amazonian Basin, Brazil, and soils from its drainage basin. The surface layers of sediments in twenty sampling points with variable depths, are representative of the different morphological sections of the reservoir. Nineteen soil samples, representing the main soil classes, were collected near the margins of the reservoir. Sediments and soils were subjected to the same array of physical, mineralogical and geochemical analyses: (1) texture, (2) characterization and semi-quantification of the clay fraction mineralogy and (3) geochemical analysis of the total concentration of major elements, organic compounds (organic C and nitrogen), soluble fractions of nutrients (P and K), exchangeable fractions (cation exchange capacity, exchangeable bases and acidity) and pH(H2O).

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A three-dimensional Direct Finite Element procedure is here presented which takes into account most of the factors affecting the interaction problem of the dam-water-foundation system, whilst keeping the computational cost at a reasonable level by introducing some simplified hypotheses. A truncated domain is defined, and the dynamic behaviour of the system is treated as a wave-scattering problem where the presence of the dam perturbs an original free-field system. The rock foundation truncated boundaries are enclosed by a set of free-field one-dimensional and two-dimensional systems which transmit the effective forces to the main model and apply adsorbing viscous boundaries to ensure radiation damping. The water domain is treated as an added mass moving with the dam. A strategy is proposed to keep the viscous dampers at the boundaries unloaded during the initial phases of analysis, when the static loads are initialised, and thus avoid spurious displacements. A focus is given to the nonlinear behaviour of the rock foundation, with concentrated plasticity along the natural discontinuities of the rock mass, immersed in an otherwise linear elastic medium with Rayleigh damping. The entire procedure is implemented in the commercial software Abaqus®, whose base code is enriched with specific user subroutines when needed. All the extra coding is attached to the Thesis and tested against analytical results and simple examples. Possible rock wedge instabilities induced by intense ground motion, which are not easily investigated within a comprehensive model of the dam-water-foundation system, are treated separately with a simplified decoupled dynamic approach derived from the classical Newmark method, integrated with FE calculation of dam thrust on the wedges during the earthquake. Both the described approaches are applied to the case study of the Ridracoli arch-gravity dam (Italy) in order to investigate its seismic response to the Maximum Credible Earthquake (MCE) in a full reservoir condition.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

• Microsatellite primers were developed for Orthophytum ophiuroides, a rupicolous bromeliad species endemic to neotropical rocky fields. These microsatellite loci will be used to investigate population differentiation and species cohesion in such fragmented environments. The loci were tested for cross-amplification in related bromeliad species. • Eleven polymorphic microsatellite markers were isolated and characterized from an enriched library of O. ophiuroides. The loci were tested on 42 individuals from two populations of this species. The number of alleles per locus ranged from three to nine and the expected and observed heterozygosities ranged from 0.167 to 0.870 and from 0.369 to 0.958, respectively. Seven loci successfully amplified in other related bromeliad species. • Our results suggest that the microsatellite loci developed here will be useful to assess genetic diversity and gene flow in O. ophiuroides for the investigation of population differentiation and species cohesion in neotropical mountainous habitats.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper examines the spatial pattern of ill-defined causes of death across Brazilian regions, and its relationship with the evolution of completeness of the deaths registry and changes in the mortality age profile. We make use of the Brazilian Health Informatics Department mortality database and population censuses from 1980 to 2010. We applied demographic methods to evaluate the quality of mortality data for 137 small areas and correct for under-registration of death counts when necessary. The second part of the analysis uses linear regression models to investigate the relationship between, on the one hand, changes in death counts coverage and age profile of mortality, and on the other, changes in the reporting of ill-defined causes of death. The completeness of death counts coverage increases from about 80% in 1980-1991 to over 95% in 2000-2010 at the same time the percentage of ill-defined causes of deaths reduced about 53% in the country. The analysis suggests that the government's efforts to improve data quality are proving successful, and they will allow for a better understanding of the dynamics of health and the mortality transition.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of the present study was to identify factors associated with the occurrence of falls among elderly adults in a population-based study (ISACamp 2008). A population-based cross-sectional study was carried out with two-stage cluster sampling. The sample was composed of 1,520 elderly adults living in the urban area of the city of Campinas, São Paulo, Brazil. The occurrence of falls was analyzed based on reports of the main accident occurred in the previous 12 months. Data on socioeconomic/demographic factors and adverse health conditions were tested for possible associations with the outcome. Prevalence ratios (PR) were estimated and adjusted for gender and age using the Poisson multiple regression analysis. Falls were more frequent, after adjustment for gender and age, among female elderly participants (PR = 2.39; 95% confidence interval (95% CI) 1.47 - 3.87), elderly adults (80 years old and older) (PR = 2.50; 95% CI 1.61 - 3.88), widowed (PR = 1.74; 95% CI 1.04 - 2.89) and among elderly adults who had rheumatism/arthritis/arthrosis (PR = 1.58; 95% CI 1.00 - 2.48), osteoporosis (PR = 1.71; 95% CI 1.18 - 2.49), asthma/bronchitis/emphysema (PR = 1,73; 95% CI 1.09 - 2.74), headache (PR = 1.59; 95% CI 1.07 - 2.38), mental common disorder (PR = 1.72; 95% CI 1.12 - 2.64), dizziness (PR = 2.82; 95% CI 1.98 - 4.02), insomnia (PR = 1.75; 95% CI 1.16 - 2.65), use of multiple medications (five or more) (PR = 2.50; 95% CI 1.12 - 5.56) and use of cane/walker (PR = 2.16; 95% CI 1.19 - 3,93). The present study shows segments of the elderly population who are more prone to falls through the identification of factors associated with this outcome. The findings can contribute to the planning of public health policies and programs addressed to the prevention of falls.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The study objective was to examine differentials in time trends and predictors of deaths assigned to symptoms, signs and ill-defined conditions in comparison with other ill-defined conditions (ill-defined cardiovascular diseases, cancer and injury) in a population-based cohort study. Of 1,606 baseline participants aged 60 years and over, 524 died during 9-year follow-up and were included in this study. Deaths coded to "symptoms" declined by 77% in the period from 1997-1999 to 2003-2005. Deaths coded to other ill-defined conditions remained unchanged. The calendar period 2003-2005 (RR = 0.25; 95%CI: 0.09-0.70) and in-hospital deaths (RR = 0.16; 95%CI: 0.08-0.34) were independently associated with "symptoms", but not with other ill-defined conditions. Baseline socio-demographic characteristics and chronic diseases were not predictors of these outcomes. International and national agencies have focused on the reduction of deaths assigned to "symptoms" to improve the registration of vital statistics, while other ill-defined conditions have received little attention. Our data provide evidence supporting the need to redress this situation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A study was carried out in the area of influence of the Porto Primavera Hydroelectric Power Station, in western São Paulo State, to investigate ecological and epidemiological aspects of malaria in the area and monitor the profile of the anopheline populations following the environmental changes brought about by the construction of the lake. Mosquitoes captured were analyzed by standardized indicator species analysis (ISA) before and during different flooding phases (253 m and 257 m elevations). The local human population was studied by means of parasitological (thin/thick blood smears), molecular (PCR) and serological tests. Serological tests consisted of Enzyme Linked Immunosorbent Assay (ELISA) with synthetic peptides of the circumsporozoite protein (CSP) from classic Plasmodium vivax, P. vivax variants (VK247 and "vivax-like"), P. malariae and P. falciparum and Indirect Immunofluorescence Assay (IFA) with asexual forms of P. vivax, P. malariae and P. falciparum. The results of the entomological survey indicated that, although the Anopheles darlingi population increased after the flooding, the population density remained very low. No malaria, parasite infection or DNA was detected in the inhabitants of the study area. However, there was a low frequency of antibodies against asexual forms and a significant prevalence of antibodies against P. vivax, P. vivax variants, P. falciparum and P. malariae; the presence of these antibodies may result from recent or less recent contact with human or simian Plasmodium (a parallel study in the same area revealed the existence of a sylvatic cycle). Nevertheless, these results suggest that, as in other places where malaria is present and potential vectors circulate, the local epidemiological conditions observed could potentially support the transmission of malaria in Porto Primavera Lake if infected individuals are introduced in sufficient numbers. Further studies are required to elucidate the phenomena described in this paper.