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  • 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.
371

Ett extra år i skolan : Konsekvenser på individ-, grupp- och organisationsnivå, sett ur ett lärarperspektiv

Ståhl, Liselotte January 2011 (has links)
Denna undersökning bygger på 13 lärares erfarenhet av att ha undervisat elever som gått ett extra år i skolan, någon gång i grundskolan mellan förskoleklass och årskurs 6. Syftet är att undersöka om det extra året bidrar till den kunskapsökning hos eleverna som lärare antar ska ske. Vidare frågeställningar är hur året organiserats för eleverna och om året medfört andra positiva och/eller negativakonsekvenser. Jag har använt mig av en kvalitativ intervjumetod, för att få ta del av lärarnas erfarenheter och upplevelser.Eftersom forskning inom ämnet i Sverige är mycket begränsad har jag till största delen utgått från internationell forskning. Mitt resultat visar att lärarna ansåg att det extra året varit mycket betydelsefullt för eleverna, både kunskapsmässigt och emotionellt. Även om det extra året inte innebar att alla kunskapsmål uppnåddes för årskursen, så var det enligt lärarna ett steg i rätt r iktning för eleverna. En slutsats som kan dras av undersökningen är att om ett extra år ska ske, så bör en väl genomtänkt och riktad pedagogisk plan göras för elevens skolarbete inför året. Vidare framkommer att behov finns avvidare forskning inom ämnet.Merparten av den internationella forskningen visar att den långsiktiga effekten av ett extra år inte är gynnsam för eleverna och i Sverige anser vår skolminister att det borde tillämpas i större utsträckning.
372

Instabilities in Higher-Dimensional Theories of Gravity

Hovdebo, Jordan January 2006 (has links)
A number of models of nature incorporate dimensions beyond our observed four. In this thesis we examine some examples and consequences of classical instabilities that emerge in the higher-dimensional theories of gravity which can describe their low energy phenomenology. <br /><br /> We first investigate a gravitational instability for black strings carrying momentum along an internal direction. We argue that this implies a new type of solution that is nonuniform along the extra dimension and find that there is a boost dependent critical dimension for which they are stable. Our analysis implies the existence of an analogous instability for the five-dimensional black ring. We construct a simple mode of the black ring to aid in applying these results and argue that such rings should exist in any number of space-time dimensions. <br /><br /> Next we consider a recently constructed class of nonsupersummetric solutions of type IIB supergravity which are everywhere smooth and have no horizon. We demonstrate that these solutions are all classically unstable. The instability is a generic feature of horizonless geometries with an ergoregion. We consider the endpoint of this instability and argue that the solutions decay to supersymmetric configurations. We also comment on the implications of the ergoregion instability for Mathur's 'fuzzball' proposal. <br /><br /> Finally, we consider an interesting braneworld cosmology in the Randall-Sundrum scenario constructed using a bulk space-time which corresponds to a charged AdS black hole. In particular, these solutions appear to 'bounce', making a smooth transition from a contracting to an expanding phase. By considering the space-time geometry more carefully, we demonstrate that generically in these solutions the brane will encounter a singularity in the transition region.
373

Determination of the role and regulation of matrix metalloproteinase-25 during mouse secondary palate formation

Brown, Graham Douglas 06 August 2009 (has links)
Development of the secondary palate (SP) is a complex event despite the small area it encompasses. Problems with SP development can lead to a cleft palate, which is one of the most common birth disorders. The matrix metalloproteinases (MMPs) are required for proper SP development, but a functional role for any one of them remains unknown. MMP-25 is a candidate MMP to have a functional role in SP formation as genetic scans of the DNA of human cleft palate patients indicate a common mutation at a region upstream of the Mmp-25 gene. The purpose of this thesis is to investigate gene expression of Mmp-25 in the developing mouse SP, whether it has a functional role in mouse SP development and begin to identify factors potentially upstream of Mmp-25 expression.<p> Mmp-25 mRNA and protein is found at all SP developmental stages in mice with highest expression at embryonic day (E) 13.5 when analyzed by quantitative real-time PCR and western blotting. Immunohistochemistry localizes MMP-25 protein primarily to the plasma membranes of palate shelf epithelial cells with secondary expression in apical mesenchymal cells. Mmp-25 knockdown with siRNA in palatal cultures resulted in a significant decrease in palate shelf fusion and persistence of the medial edge epithelium in vitro. Mmp-25 mRNA and protein levels are significantly decreased in vitro when cultured palate shelves are incubated in growth medium with 5 ìg/ml of a TGFâ3-neutralizing antibody. Mmp-25 gene expression is highest at E12.5 and E13.5, which corresponds to increasing palate shelf growth downward alongside the tongue. Immunohistochemistry localized MMP-25 protein expression predominantly in the epithelium of the palate shelves, but also in areas of the mesenchyme that were immediately adjacent to the epithelium and apical in location. Knockdown of Mmp-25 expression resulted in palate shelf fusion being impaired and significant medial edge epithelium remaining in contacted areas. Bioneutralization of TGFâ3 resulted in a significant decrease in Mmp-25 gene expression. These data suggest a functional role for MMP-25 in mouse SP development by removing extra-cellular matrix barriers to increased palate shelf growth and place its expression downstream of TGF-â3 signaling. This is the first research to present a role for a single MMP in mouse SP development.
374

Modelling reflected polarized light from exoplanetary atmospheres

Aronson, Erik January 2011 (has links)
I present numerical simulations of intensity and degree of polarization of light reflected by Earth-like exoplanets. The results are presented as a function of wavelength, and for a few different phase angles and a few different points on the planet. At this stage the aim is to show the working code and test a few different set ups of the star-planet system in order to find preferable configurations for observations. Not surprisingly, phase angle 90◦ shows the largest degree of polarization. For beneficial wavelength regions, visual light shows a larger overall degree of polarization, while NIR shows very clear absorption patterns in the degree of polarization, making detection of the atmospheric composition possible.
375

A Mechanical Fluid Assessment of Anatomical Models of the Total Cavopulmonary Connection (TCPC)

de Julien de Zelicourt, Diane Alicia 09 December 2004 (has links)
BACKGROUND: Understanding the hemodynamics of the total cavopulmonary connection (TCPC) may lead to further optimization of the connection design and surgical planning, which in turn may lead to improved surgical outcome. While most experimental and numerical investigations have mainly focused on somewhat simplified geometries, the investigation of the flow field of true TCPC configurations is necessary for a true understanding. METHODS: This study details a manufacturing methodology yielding more accurate in vitro models that would provide a better understanding of the TCPC hemodynamics and adequate data for the validation of anatomical CFD simulations. This approach is illustrated on two different TCPC templates: an intra-atrial TCPC with a single superior vena cava (SVC) and a bilateral SVC with an extra-cardiac conduit. Power loss, flow visualization, digital particle image velocimetry (DPIV) flow measurements as well as computational fluid dynamics simulations are performed to characterize the anatomic flow structure. Additional parametric glass models of the TCPC were manufactured to help understand the fluid dynamics of the anatomical models and support the computational model validation effort. RESULTS/CONCLUSIONS: Both anatomic configurations revealed very different fluid dynamics underlining once again the need for at least one comprehensive experimental campaign per TCPC template for a good understanding of the flow phenomena. The absence of caval offset in the anatomical intra-atrial model resulted in important flow turbulence, which was enhanced by the large connection area and yielded high pressure drops and power losses. On the other hand, the bilateral SVC, which featured a smooth extra-cardiac conduit and wider vessels, led to power losses that were one order of magnitude lower than those of the anatomic intra-atrial model and a smooth flow field with lower levels of instability. The simplified glass models demonstrated that the diameter of the connecting vessels and of the pulmonary arteries in particular, was a parameter of prime importance. Finally, this study also reports on a combined experimental and numerical validation methodology, suggesting a cautious approach for the straightforward use of available CFD tools and pointing out the need for developing high resolution CFD techniques specifically tailored to tackle the complexities of cardiovascular flows.
376

Wind Tunnel and Flight Testing of Active Flow Control on a UAV

Babbar, Yogesh 2010 May 1900 (has links)
Active flow control has been extensively explored in wind tunnel studies but successful in-flight implementation of an active flow control technology still remains a challenge. This thesis presents implementation of active flow control technology onboard a 33% scale Extra 330S ARF aircraft, wind tunnel studies and flight testing of fluidic actuators. The design and construction of the pulsed blowing system for stall suppression (LE actuator) and continuous blowing system for roll control (TE actuator) and pitch control have been presented. Full scale wind tunnel testing in 7̕ X 10 Oran W. Nicks low speed wind tunnel shows that the TE actuators are about 50% effective as the conventional ailerons. The LE actuator is found to be capable of suppressing stall from 12° to about 22°. Comparison of characteristics of Active elevator and conventional elevator in 3' X 4' low speed wind tunnel show that, the active elevator is as effective as of conventional elevator deflected at 5°. Flight tests show that TE actuators are able to control the aircraft in flight in banked turns. The measured roll rates in-flight support the wind tunnel test findings.
377

The Evolution Of Intra And Extra Eu-15 Agricultural Trade: The Impact Of The Cap Reform And The Uraa

Kucuk, Gamze 01 September 2008 (has links) (PDF)
In this thesis, intra and extra European Union-15 agricultural trade is investigated for the period 1985 - 2005. The main purpose of this study is to find out to what extent the two major events of this period, the CAP reform of mid-1990&rsquo / s and the Uruguay Round Agreement on Agriculture (URAA) of 1995, changed the relative shares of extra and intra trade in overall agricultural trade. The efforts to make European agriculture more competitive and more integrated with the world market have not concluded in a way that the dominance of intra trade over extra trade is relieved. The intra trade still dominates the EU-15 agricultural trade as it has been dominating since 1985. European agricultural market has become more open to world products only in some product groups. Similarly, liberalizing reforms had limited impact on EU-15 countries on individual basis. The shares of intra trade and extra trade remained more and less stable in most of the member states.
378

Search For Scalar And Tensor Unparticles In The Diphoton Final State In Cms Experiment At The Lhc

Akin, Ilina Vasileva 01 September 2009 (has links) (PDF)
We present a search for scalar and tensor unparticles in the diphoton final state produced in pp collisions at a center-of-mass energy of 10 TeV, with the CMS detector at LHC. The analysis focuses on the data sample corresponding to the integrated luminosity of 100 pb&amp / #8722 / 1, expected to be collected in the first LHC run. The exclusion limits on unparticle parameters, scaling dimension dU and coupling constant lambda, and the discovery potential for unparticles are presented. This is the first simulation study of the sensitivity to unparticles decaying into the diphoton final state at a hadron collider.
379

Cleanup 2,4-Dichlorophenol-contaminated Groundwater Useing Bioremediation Technology

Chen, Ku-Fan 29 August 2001 (has links)
none
380

Diallel analysis and heritability estimates of fiber traits for ELS, Gossypium hirsutum L., progeny.

Berger, Gregory L. 16 January 2010 (has links)
With a demand for high-quality cotton fiber in international markets, improvement of fiber quality in U.S. grown commercial cultivars is necessary. Smith, Hague, Thaxton, and Jones developed a group of experimental lines in 2008 that produced extra-long staple fiber (>35.6 mm). This study determined general combining ability (GCA), and specific combining ability (SCA) of four experimental ELS lines and four commercial cultivars utilizing biplot and conventional diallel analysis, determined performance of F2 progeny, calculated broad-sense (H2) heritability estimates for F2 progeny, and verified the ability of selected parental combinations to produce variable segregating populations with variability of fiber traits. Initial crosses were made in 2007, with additional crosses being made in the field and in a greenhouse in 2008. F1 progeny and parents were grown in a replicated trial near College Station, TX, in 2007 and 2008. F2 progeny lines and parents were grown in replicated trials at two locations in 2008. Due to a significant GxY interaction for all F1 fiber traits, data were reported by years. Experimental ELS lines showed positive GCA effects for fiber length, strength, and length uniformity, while the majority of commercial lines showed negative effects. These findings suggest experimental ELS lines contain alleles for fiber length and strength not present in this particular set of commercial cultivars. Experimental ELS lines exhibited negative GCA effects for lint percent, which suggests further selection is needed for these lines to be commercially competitive. Performances of F2 lines suggest differences in fiber traits are predominantly due to additive gene action. Furthermore, data suggests alleles for fiber length and strength is present in the experimental ELS lines not present in the commercial cultivars. F2 progeny exhibited moderate heritability for all fiber traits. Sufficient variability exists within selected F2 progeny to select for phenotypes exhibiting improved fiber quality over commercial cultivar potential with similar agronomic qualities of commercial cultivars. The ELS lines are a useful source of germplasm for plant breeders looking to improve fiber qualities in their programs.

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