987 resultados para The East


Relevância:

70.00% 70.00%

Publicador:

Resumo:

The Book of John Mandeville, while ostensibly a pilgrimage guide documenting an English knight’s journey into the East, is an ideal text in which to study the developing concept of race in the European Middle Ages. The Mandeville-author’s sense of place and morality are inextricably linked to each other: Jerusalem is the center of his world, which necessarily forces Africa and Asia to occupy the spiritual periphery. Most inhabitants of Mandeville’s landscapes are not monsters in the physical sense, but at once startlingly human and irreconcilably alien in their customs. Their religious heresies, disordered sexual appetites, and monstrous acts of cannibalism label them as fallen state of the European Christian self. Mandeville’s monstrosities lie not in the fantastical, but the disturbingly familiar, coupling recognizable humans with a miscarriage of natural law. In using real people to illustrate the moral degeneracy of the tropics, Mandeville’s ethnography helps shed light on the missing link between medieval monsters and modern race theory.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

I. Foehn winds of southern California.
An investigation of the hot, dry and dust laden winds occurring in the late fall and early winter in the Los Angeles Basin and attributed in the past to the influences of the desert regions to the north revealed that these currents were of a foehn nature. Their properties were found to be entirely due to dynamical heating produced in the descent from the high level areas in the interior to the lower Los Angeles Basin. Any dust associated with the phenomenon was found to be acquired from the Los Angeles area rather than transported from the desert. It was found that the frequency of occurrence of a mild type foehn of this nature during this season was sufficient to warrant its classification as a winter monsoon. This results from the topography of the Los Angeles region which allows an easy entrance to the air from the interior by virtue of the low level mountain passes north of the area. This monsoon provides the mild winter climate of southern California since temperatures associated with the foehn currents are far higher than those experienced when maritime air from the adjacent Pacific Ocean occupies the region.

II. Foehn wind cyclo-genesis.
Intense anticyclones frequently build up over the high level regions of the Great Basin and Columbia Plateau which lie between the Sierra Nevada and Cascade Mountains to the west and the Rocky Mountains to the east. The outflow from these anticyclones produce extensive foehns east of the Rockies in the comparatively low level areas of the middle west and the Canadian provinces of Alberta and Saskatchewan. Normally at this season of the year very cold polar continental air masses are present over this territory and with the occurrence of these foehns marked discontinuity surfaces arise between the warm foehn current, which is obliged to slide over a colder mass, and the Pc air to the east. Cyclones are easily produced from this phenomenon and take the form of unstable waves which propagate along the discontinuity surface between the two dissimilar masses. A continual series of such cyclones was found to occur as long as the Great Basin anticyclone is maintained with undiminished intensity.

III. Weather conditions associated with the Akron disaster.
This situation illustrates the speedy development and propagation of young disturbances in the eastern United States during the spring of the year under the influence of the conditionally unstable tropical maritime air masses which characterise the region. It also furnishes an excellent example of the superiority of air mass and frontal methods of weather prediction for aircraft operation over the older methods based upon pressure distribution.

IV. The Los Angeles storm of December 30, 1933 to January 1, 1934.
This discussion points out some of the fundamental interactions occurring between air masses of the North Pacific Ocean in connection with Pacific Coast storms and the value of topographic and aerological considerations in predicting them. Estimates of rainfall intensity and duration from analyses of this type may be made and would prove very valuable in the Los Angeles area in connection with flood control problems.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Despite years of research on low-angle detachments, much about them remains enigmatic. This thesis addresses some of the uncertainty regarding two particular detachments, the Mormon Peak detachment in Nevada and the Heart Mountain detachment in Wyoming and Montana.

Constraints on the geometry and kinematics of emplacement of the Mormon Peak detachment are provided by detailed geologic mapping of the Meadow Valley Mountains, along with an analysis of structural data within the allochthon in the Mormon Mountains. Identifiable structures well suited to constrain the kinematics of the detachment include a newly mapped, Sevier-age monoclinal flexure in the hanging wall of the detachment. This flexure, including the syncline at its base and the anticline at its top, can be readily matched to the base and top of the frontal Sevier thrust ramp, which is exposed in the footwall of the detachment to the east in the Mormon Mountains and Tule Springs Hills. The ~12 km of offset of these structural markers precludes the radial sliding hypothesis for emplacement of the allochthon.

The role of fluids in the slip along faults is a widely investigated topic, but the use of carbonate clumped-isotope thermometry to investigate these fluids is new. Faults rocks from within ~1 m of the Mormon Peak detachment, including veins, breccias, gouges, and host rocks, were analyzed for carbon, oxygen, and clumped-isotope measurements. The data indicate that much of the carbonate breccia and gouge material along the detachment is comminuted host rock, as expected. Measurements in vein material indicate that the fluid system is dominated by meteoric water, whose temperature indicates circulation to substantial depths (c. 4 km) in the upper crust near the fault zone.

Slip along the subhorizontal Heart Mountain detachment is particularly enigmatic, and many different mechanisms for failure have been proposed, predominantly involving catastrophic failure. Textural evidence of multiple slip events is abundant, and include multiple brecciation events and cross-cutting clastic dikes. Footwall deformation is observed in numerous exposures of the detachment. Stylolitic surfaces and alteration textures within and around “banded grains” previously interpreted to be an indicator of high-temperature fluidization along the fault suggest their formation instead via low-temperature dissolution and alteration processes. There is abundant textural evidence of the significant role of fluids along the detachment via pressure solution. The process of pressure solution creep may be responsible for enabling multiple slip events on the low-angle detachment, via a local rotation of the stress field.

Clumped-isotope thermometry of fault rocks associated with the Heart Mountain detachment indicates that despite its location on the flanks of a volcano that was active during slip, the majority of carbonate along the Heart Mountain detachment does not record significant heating above ambient temperatures (c. 40-70°C). Instead, cold meteoric fluids infiltrated the detachment breccia, and carbonate precipitated under ambient temperatures controlled by structural depth. Locally, fault gouge does preserve hot temperatures (>200°C), as is observed in both the Mormon Peak detachment and Heart Mountain detachment areas. Samples with very hot temperatures attributable to frictional shear heating are present but rare. They appear to be best preserved in hanging wall structures related to the detachment, rather than along the main detachment.

Evidence is presented for the prevalence of relatively cold, meteoric fluids along both shallow crustal detachments studied, and for protracted histories of slip along both detachments. Frictional heating is evident from both areas, but is a minor component of the preserved fault rock record. Pressure solution is evident, and might play a role in initiating slip on the Heart Mountain fault, and possibly other low-angle detachments.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

The East African Great Lakes are now well known for (1) their fisheries, of vital importance for their rapidly rising riparian human populations, and (2) as biodiversity hotspots with spectacular endemic faunas, of which the flocks of cichlid fishes unique to each of the three largest lakes, Tanganyika, Malawi and Victoria, offer unique opportunities to investigate how new species evolve and coexist. Since the early 1990s research involving over a hundred scientists, financed by many international bodies, has produced numerous reports and publications in widely scattered journals. This article summarizes their main discoveries and examines the status of, and prospects for, the fisheries, as well as current ideas on how their rich endemic fish faunas have evolved. It first considers fisheries projects in each of the three lakes: the deep rift valley lakes Tanganyika and Malawi and the huge Victoria, all of which share their waters between several East African countries. Secondly it considers the biodiversity surveys of each lake, based on underwater (SCUBA) observations of fish ecology and behaviour which have revealed threats to their fish faunas, and considers what conservation measures are needed. Thirdly, using the lakes as laboratories, what have the international investigations (including DNA techniques and follow-up aquarium experiments) now revealed about the origins and relationships of their cichlid species flocks and mechanisms of evolution?

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Upland stream systems have been extensively investigated in Europe, North America and Australasia and many of the central ideas concerning their function are based on these systems. One central paradigm, the river continuum concept is ultimately derived from those North American streams whose catchments remain forested with native vegetation. Streams of the tropics may or may not fit the model. They have been little studied. The Amani Nature Reserve in the East Usambara Mountains of north-eastern Tanzania offers an opportunity to bring these naturally forested systems to the attention of the ecological community. This article describes a comparison made between two lengths of the River Dodwe in this area. The work was carried out by a group of postgraduate students from eighteen European and African countries with advice from five staff members, as part of a course organised by the Tropical Biology Association. Rigorous efforts were made to standardise techniques, in a situation where equipment and laboratory facilities were very basic, through a management structure and deliberate allocation of work to specialists in each area.The article offers a summary of invertebrate communities found in the stream and its biomass. Crabs seem to be the key organism in both sections of the streams.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

With the installation by the Pacific Electric Railway of a bus system in Pasadena to supplant most of its trolley lines, the problem of the comparison of the costs of the two systems naturally presented itself. The study here undertaken was originally started as just a comparison of the motor bus and Birney Safety Car, but as the work progressed it seemed advisable to include the trolley bus as well - a method of transportation that is comparatively new as far as development is concerned, but which seems to be finding increasing favor in the East.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

The eastern part of the Ventura Basin contains great thicknesses of non-marine Tertiary sediments. The lower formations of the Tertiary strata outcrop in the Tick Canyon Area and are described in this report. Emphasis is placed on the description of the Vasquez formation which is the lowest Tertiary unit in the Tick Canyon Area and which contains the only Tertiary lavas found in the East Ventura Basin.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

The earliest Chinese ancient glasses before the West Han Dynasty (200 BC) from different regions are studied. The glass samples were unearthed from Hunan, Hubei, Yunnan, Sichuan, Guizhou, Guangdong and Xinjiang of China. The chemical composition of these glasses samples is analyzed by proton induced X-ray emission (PIXE) technique, energy dispersive X-ray fluorescence (EDXRF) method and inductively coupled plasma atomic emission spectrometry (ICP-AES). It is shown that the glass chemical compositions belong to barium-lead silicate BaO-PbO-SiO2, potash soda lime silicate K2O (Na2O)-CaO-SiO2 (K2O/Na2O > 1), soda potash lime silicate Na2O (K2O)-CaO-SiO2 (K2O/Na2O < 1) and potash silicate K2O-SiO2 glass systems, respectively. The origins of the earliest Chinese ancient glasses are discussed from the archaeological and historical points of view. These four types of Chinese ancient glasses were all made in Chinese territory using local raw materials. The glass preparation technology was related to the Chinese ancient bronze metallurgy and proto-porcelain glaze technology. The glass technology relationship between the East and the West is analyzed at the same time.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Citharichthys cornutus and C. gymnorhinus, diminutive flatfishes inhabiting continental shelves in the western Atlantic Ocean, are infrequently reported and poorly known. We identified 594 C. cornutus in 56 different field collections (68–287 m; most between 101–200 m) off the eastern United States, Bahamas, and eastern Caribbean Sea. Historical records and recently captured specimens document the northern geographic range of adults on the shelf off New Jersey (40°N, 70°W). Citharichthys cornutus measured 17.2–81.3 mm standard length (SL); males (20.0–79.1 mm SL) and females (28.0–81.3 mm SL) attain similar sizes (sex could not be determined for fish <20 mm SL). Males reach nearly 100% maturity at ≥60 mm SL. The smallest mature females are 41.5 mm SL, and by 55.1 mm SL virtually all are mature. Juveniles are found with adults on the outer shelf. Only 214 C. gymnorhinus were located in 42 different field collections (35–201 m, with 90% between 61 and 120 m) off the east coast of the United States, Bahamas, and eastern Caribbean Sea. Adults are found as far north as the shelf off Cape Hatteras, NC (35°N, 75°W). This diminutive species (to 52.4 mm SL) is among the smallest flatfishes but males (n=131; 20.3–52.4 mm SL) attain a slightly larger maximum size than that of females (n=58; 26.2–48.0 mm SL). Males begin to mature between 29 and 35 mm SL and reach 100% maturity by 35–40 mm SL. Some females are mature at 29 mm SL, and all females >35.1 mm SL are mature. Overlooked specimens in museum collections and literature enabled us to correct long-standing inaccuracies in northern distributional limits that appear in contemporary literature and electronic data bases for these species. Associated locality-data for these specimens allow for proper evaluation of distributional information for these species in relation to hypotheses regarding shifts in species ranges due to climate change effects.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Age, growth, and reproductive data were obtained from dolphinfish (Coryphaena hippurus, size range: 89 to 1451 mm fork length [FL]) collected between May 2002 and May 2004 off North Carolina. Annual increments from scales (n=541) and daily increments from sagittal otoliths (n=107) were examined; estimated von Bertalanffy parameters were L∞ (asymptotic length)=1299 mm FL and k (growth coefficient)=1.08/yr. Daily growth increments reduced much of the residual error in length-at-age estimates for age-0 dolphinfish; the estimated average growth rate was 3.78 mm/day during the first six months. Size at 50% maturity was slightly smaller for female (460 mm FL) than male (475 mm FL) dolphinfish. Based on monthly length-adjusted gonad weights, peak spawning occurs from April through July off North Carolina; back-calculated hatching dates from age-0 dolphinfish and prior reproductive studies on the east coast of Florida indicate that dolphinfish spawning occurs year round off the U.S. east coast and highest levels range from January through June. No major changes in length-at-age or size-at-maturity have occurred since the early 1960s, even after substantial increases in fishery landings.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

During the 1990s, sea otter (Enhydra lutris) counts in the Aleutian archipelago decreased by 70% throughout the archipelago between 1992 and 2000. Recent aerial surveys in the Aleutians did not identify the eastward extent of the decline; therefore we conducted an aerial survey along the Alaska Peninsula for comparison with baseline information. Since 1986, abundance estimates in offshore habitat have declined by 27– 49% and 93 –94% in northern and southern Alaska Peninsula study areas, respectively. During this same time period, sea otter density has declined by 63% along the island coastlines within the south Alaska Peninsula study area. Between 1989 and 2001, sea otter density along the southern coastline of the Alaska Peninsula declined by 35% to the west of Castle Cape but density increased by 4% to the east, which may indicate an eastward extent of the decline. In all study areas, sea otters were primarily concentrated in bays and lagoon, whereas historically, large rafts of otters had been distributed offshore. The population declines observed along the Alaska Peninsula occurred at roughly the same time as declines in the Aleutian islands to the east and the Kodiak archipelago to the west. Since the mid-1980s, the sea otter population throughout southwest Alaska has declined overall by an estimated 56–68%, and the decline may be one of the most significant sea otter conservation issues in our time.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Zostera marina is a member of a widely distributed genus of seagrasses, all commonly called eelgrass. The reported distribution of eelgrass along the east coast of the United States is from Maine to North Carolina. Eelgrass inhabits a variety of coastal habitats, due in part to its ability to tolerate a wide range of environmental parameters. Eelgrass meadows provide habitat, nurseries, and feeding grounds for a number of commercially and ecologically important species, including the bay scallop, Argopecten irradians. In the early 1930’s, a marine event, termed the “wasting disease,” was responsible for catastrophic declines in eelgrass beds of the coastal waters of North America and Europe, with the virtual elimination of Z. marina meadows in the Atlantic basin. Following eelgrass declines, disastrous losses were documented for bay scallop populations, evidence of the importance of eelgrass in supporting healthy scallop stocks. Today, increased turbidity arising from point and non-point source nutrient loading and sediment runoff are the primary threats to eelgrass along the Atlantic coast and, along with recruitment limitation, are likely reasons for the lack of recovery by eelgrass to pre-1930’s levels. Eelgrass is at a historical low for most of the western Atlantic with uncertain prospects for systematic improvement. However, of all the North American seagrasses, eelgrass has a growth rate and strategy that makes it especially conducive to restoration and several states maintain ongoing mapping, monitoring, and restoration programs to enhance and improve this critical resource. The lack of eelgrass recovery in some areas, coupled with increasing anthropogenic impacts to seagrasses over the last century and heavy fishing pressure on scallops which naturally have erratic annual quantities, all point to a fishery with profound challenges for survival.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

This is a broad historical overview of the bay scallop, Argopecten irradians, fishery on the East and Gulf Coasts of North America (Fig. 1). For a little over a century, from about the mid 1870’s to the mid 1980’s, bay scallops supported large commercial fisheries mainly in the U.S. states of Massachusetts, New York, and North Carolina and on smaller scales in the states in between and in western Florida. In these states, the annual harvests and dollar value of bay scallops were far smaller than those of the other important commercial mollusks, the eastern oysters, Crassostrea virginica, and northern quahogs, Mercenaria mercenaria, but they were higher than those of softshell clams, Mya arenaria (Table 1). The fishery had considerable economic importance in the states’ coastal towns, because bay scallops are a high-value product and the fishery was active during the winter months when the economies in most towns were otherwise slow. The scallops also had cultural importance as a special food, an ornament owing to its pretty shell design, and an interesting biological component of

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Mexico has an oyster industry of substantial size, ranking about sixth in the world. In 1993, among the top ten oyster producers, Korea, Japan, the United States, China, and France ranked ahead of Mexico, while the Philippines, Australia, Canada, and New Zealand trailed it (Fig. 1). On its east coast, the species landed is the eastern oyster, Crassostrea virginica, while on its west coast C. corteziensis, C. iridescens, and the Pacific oyster, C. gigas, are landed. During the last 10-15 years, annual production often was at least 50,000 t of shelled oysters, or nearly 1.5 million bushels (Anonymous, 1995), with the great preponderance (90%) coming from a series of lagoons connecting with the Gulf of Mexico along the east coast (Fig. 2) and the remainder produced on the west coast.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Oyster landings in the United States and Canada have been based mainly on three species, the native eastern oyster, Crassostrea virginica, native Olympia oyster, Ostreola conchaphila, and introduced Pacific oyster, C. gigas. Landings reached their peak of around 27 million bushels/year in the late 1800's and early 1900's when eastern oysters were a common food throughout the east coast and Midwest. Thousands of people were involved in harvesting them with tongs and dredges and in shucking, canning, packing, and transporting them. Since about 1906, when the United States passed some pure food laws, production has declined. The causes have been lack of demand, siltation of beds, removal of cultch for oyster larvae while harvesting oysters, pollution of market beds, and oyster diseases. Production currently is about 5.6 million bushels/year.