• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 483
  • 107
  • 98
  • 66
  • 50
  • 19
  • 18
  • 10
  • 8
  • 7
  • 6
  • 5
  • 5
  • 5
  • 4
  • Tagged with
  • 1135
  • 115
  • 86
  • 81
  • 70
  • 65
  • 64
  • 58
  • 54
  • 54
  • 52
  • 52
  • 45
  • 45
  • 45
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
631

Dermacentor Andersoni and Rocky Mountain spotted fever in national forest recreational sites of Utah

Herrin, C. Selby 12 April 1966 (has links)
The objectives of this study were to determine (1) the prevalence of adult ticks of Dermacentor andersoni in national forest recreational sites of Utah, and (2) the incidence of spotted fever rickettsia, Rickettsia rickettsii, in the ticks of these areas. With the use of a white flannel cloth, 358 adult D. andersoni (135 males and 223 females) were collected from 48 recreational sites during the spring and summer of 1964. Ticks from each collection were put in pools, preserved in non-fat skim milk at -30° C, and subsequently tested for the presence of spotted fever rickettsia by guinea pig inoculations. The average collection rate (population density) for all collections was 6.8 per hour, but populations varied between sites. Populations were greater in the middle and southern parts of the state than in the northern. The greatest populations were at elevations between 6,000 and 8,000 feet with the upper limit just under 9,000 feet. The elevational distribution varied with the latitude--greater populations were found at higher elevations in southern than in northern Utah. The season of peak abundance was between the last week of May and the last of June. Populations were greater at lower elevations early in the season and at higher elevations later. Male ticks were more abundant early in the spring whereas females predominated later. The preferred habitat was open, unshaded areas of short, scanty, young grass. Ticks were collected in greater numbers in the afternoon than in the morning. Temperatures between 12° and 38° C apparently had little effect on tick activity. Activity was slightly greater on partly cloudy and cloudy days than on clear days, and increased proportionately relative to an increase in wind velocity. Spotted fever rickettsia were found in 3.6% of the ticks collected. These were from 13 different recreational sites, over half of which are in the northern half of the state near human population centers. Ticks positive for spotted fever were probably infected with avirulent type U or type T strain of R. rickettsii.
632

Geological and Precious Metal Evolution at Freegold Mountain, Dawson Range, Yukon

McInnes, Brent Ian Alexander 10 1900 (has links)
<p> Freegold Mountain is part of a northwesterly trending volcanoplutonic arc comprising the eastern portion of the Yukon Crystalline Terrane. Plutonic rocks in the area intrude Paleozoic metasediments and consist of a Late Triassic to Early Cretaceous granodiorite intruded by the Big Creek Syenite dated at 138 ± 10 Ma. A suite of K-rich intrusive volcanic rocks comprise an early period of basalt-andesite-dacite volcanism and a later rhyolitic volcanism dated at 78 ± 6 Ma. Volcanic rocks at Freegold Mountain can be correlated with Mt. Nansen Volcanics.</p> <p> Two sets of fracture planes, oriented at 165/70E and 18/80W, show dextral and sinistral displacement, respectively. Rhyolite dykes and gold-quartz veins predominantly oriented NNE have been emplaced along the 18/80W extensional fracture systems. These fractures may be modelled as high-angle Reidel shears, although evidence indicates that fracture orientations and fault movement have been complicated by changing stress fields from middle Cretaceous to Tertiary time.</p> <p> The gold-bearing quartz veins at Freegold Mountain are high grade, low-tonnage deposits with grades ranging from 0.4 to 1.0 oz/t. Fluid inclusions from the lower portions of the Laforma mine homogenize at 185° C with salinity ranging between 2 and 4.5 wt. % NaCl equivalent. A boiling zone has been detected above the deeper ore where fluid inclusions show extreme ranges in homogenization temperatures (165-430° C) and salinity (4 - 43 wt. % NaCl). Fluid inclusion waters have stable isotopic signatures indicative of meteoric water with 𝛿D = -138 and 𝛿^18O = -18.4. Boiling of the Laforma fluid has caused a shift towards heavier hydrogen and oxygen isotopic values, mineral deposition and appears to enhance gold precipitation over non-boiling zones. Stable isotopic evidence indicates that the paleolatitude of Freegold Mountain during late Cretaceous time was south of the present day Yukon-B.C. border.</p> <p> The Emmons Hill (Dart) prospect is a gold-bearing vein-breccia with a mineral assemblages of barite, stibnite, marcasite, cinnabar, orpiment, Fe and Mn carbonates and chalcedonic silica. Fluid inclusions from these deposits homogenize between 140-185° with salinities of 0-0.5 wt. % NaCl. This property shows marked similarities to acid-sulphate type precious metal deposits in New Zealand and western United States.</p> <p> Large (x to xx Mt) northwesterly trending diatremes appear to be structurally controlled by small transcurrent faults parallel to and coeval with displacement along the Tintina fault. The Antoniuk diatreme (3.7 Mt @ 1.14 g/t Au) consists of heterolithic and monolithic breccias intruded by dacite and rhyolite dykes. Diamond drilling indicates that a large body of fine to medium grained alaskite is present beneath the auriferous breccia. The deposit formed by the explosive escape of volatile components evolved from the retrograde boiling of a silicic magma chamber. Gold mineralization in the breccia is associated with pyrite and arsenopyrite formed at temperatures around 300°C and salinities of about 4.5 wt. % NaCl.</p> / Thesis / Master of Science (MSc)
633

The Influence of Symbolic Meanings on the Return Migration of Êzîdîs : A Semiological Analysis of the Role of Sinjar Mountain for Internally Displaced Êzîdîs

Vargün Alıtkan, Selen January 2023 (has links)
This study explores the role of Sinjar Mountain in the return migration decisions of internally displaced Êzîdîs, who sought refuge in Iraq's camps after a devastating massacre in August 2014. Employing a semiotic approach, data was gathered via semi-structured interviews with NGO representatives and the analysis of visual videos. The findings reveal profound symbolic meanings associated with the mountain and their diverse interpretations within the Êzîdî community. Despite the mountain's ordinary physical appearance, this research reveals its deeper significance and explores the concept of topophilia or the love of a specific place, in the context of return migration. The pivotal role of the sacred Sinjar Mountain in motivating Êzîdîs to return to their homeland is demonstrated. Contributing new insights to the field, this work enhances our understanding of the complex relationship between symbolic landscapes and the decisions made by displaced populations.
634

Alpine plant succession near Mount Emmons, Uinta Mountains, Utah

Murdock, Joseph R. 01 May 1951 (has links)
It was to provide some detailed information about the alpine flora , particularly as it relates to successional aspects , that the present study was undertaken . The environmental conditions of weather and soil , as they effect floral composition , are important factors in the plant succession or alpine communities . The investigation was designed to uncover such information about the alpine flora and environment necessary to establish the pattern of succession .
635

A Phase of the Upper Devonian of Western Highland County, Virginia

Foreman, Helen Pulver January 1948 (has links)
No description available.
636

Fluid History of the Sideling Hill Syncline, Hancock County, Maryland

Lacek, William Joseph 27 July 2015 (has links)
No description available.
637

An Electron Microscopy Investigation of Gold and Associated Minerals from Round Mountain, Nevada

Burke, Michelle Lynn 06 August 2015 (has links)
No description available.
638

Tectonic and Sequence Stratigraphic Implications of the Morrison Formation-Buckhorn Conglomerate Transition, Cedar Mountain, East-central Utah

Roca, Xavier Argemi 25 March 2004 (has links)
No description available.
639

Dynamics and Variability of Foehn Winds in the McMurdo Dry Valleys Antarctica

Steinhoff, Daniel Frederick 25 July 2011 (has links)
No description available.
640

Development and Construction of a Mechanically Sprung Shock Absorber with Adjustable Spring Stiffness for Mountain Bikes / Utveckling och konstruktion av en mekaniskt fjädrad stötdämpare med justerbar styvhet för terrängcykling

Holm, Martin January 2021 (has links)
In this thesis project, the possibility to make use of a mechanical spring to achieve stiffness adjustability in a shock absorber for mountain bikes is evaluated. A mechanical spring increases the shock absorber’s sensitivity compared to a fully adjustable air spring. Today, there are no mechanical springs available on the market that offer enough stiffness adjustment to suit different riders with large variation in weight. Therefore, a mechanical spring with a wide stiffness adjustment range could be ground-breaking if it is possible to implement in mountain bike shock absorbers. The work has been carried out in accordance with a product- and concept development approach where the final concept design has been optimised analytically and verified numerically. The developed spring has been integrated in a new damper design and the complete damper and spring system has been dimensioned to fit current mountain bike frames. The result is a prototype shock absorber with a spring to suit riders between 70-88kg. An alternative spring for cyclists between 59-75kg has also been proposed. Since these springs have been made to fit current mountain bikes, it was possible to conclude that a mechanical spring witha wide range of adjustable stiffness is feasible for mountain bike application. With available spring steels, it is not possible to accommodate every rider with only one spring. It is however possible to achieve adjustment that is suitable for a rider weight range of roughly 15-16kg. This is between 70-110% more than similar products available on the market can offer. / I detta examensarbete utvärderas möjligheten att använda en mekanisk fjäder för att uppnå justerbar fjäderstyvhet hos en stötdämpare avsedd för terrängcykling. En mekanisk fjäder ökar stötdämparens känslighet jämfört med en fullt justerbar luftfjäder. I dagsläget finns på marknadeningen mekanisk fjäder vilken kan erbjuda tillräcklig justeringsmån för att passa cyklister med stor viktvariation. Därför kan en mekanisk fjäder med ett brett styvhetsspann vara banbrytande om en sådan kan tillämpas på dagens terrängcyklar. Arbetet har utförts som ett produkt- och konceptutvecklingsprojekt där den slutliga konceptdesignen har optimerats analytiskt och verifierats numeriskt. Den fjäder som tagits fram har integrerats i en ny dämparkonstruktion och stötdämparsystemet har dimensionerats för att passa dagens terrängcyklar. Resultatet är en prototyp av en stötdämpare med en fjäder som passar cyklister mellan 70-88kg. En alternativ fjäder passande cyklister mellan 59-75kg har också tagits fram. Eftersom en justerbar fjäder vars design möjliggör användning i en stötdämpare för dagens terrängcyklar har slutsatsen dragits att en justerbar mekanisk fjäder kan fungera inom detta tillämpningsområde. Det är inte möjligt med dagens material att utforma en mekanisk fjäder med tillräckligt justerbar styvhet föratt passa alla åkare. Det är däremot möjligt att använda en fjäder som passar cyklister inom ett viktspann på omkring 15-17kg. Detta är mellan 70–110% mer än vad liknande produkter tillgängliga på marknaden idag kan erbjuda.

Page generated in 0.0868 seconds