• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 442
  • 79
  • 76
  • 38
  • 28
  • 22
  • 9
  • 8
  • 5
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • Tagged with
  • 866
  • 98
  • 81
  • 79
  • 70
  • 60
  • 60
  • 57
  • 54
  • 47
  • 47
  • 47
  • 42
  • 41
  • 40
  • 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.
531

Känner du rätt person? : En studie om sociala kontaktnätets betydelse vid anställning av civilekonomer / Do you have the right contacts?

Ek, Mattias, Grändås, Ola, Lundgren, Per January 2013 (has links)
Bakgrund: 2010 presenterade SCB en undersökning om hur 403 000 jobb tillsattes (GP 2010). 79 000 av dessa tjänster tillsattes via personliga kontakter och ytterligare 100 000 där arbetsgivaren själv kontaktade den arbetssökande. Denna trend i användandet av det sociala kontaktnätet får stöd av Lena Hensvik, doktorand i nationalekonomi, i tidskriften Framtider (2012). Hon skriver att den sociala omgivningen såsom grannar, skolkamrater, tidigare kollegor och föräldrar har stor betydelse för hur vi får anställning eller inte. Hon menar att kontaktnätet är en viktig självinvestering då vårdandet av ens nätverk uppenbarligen kan underlätta jobbsökandet. Hensvik (2012) fortsätter skriva att det i dagens samhälle inte bara handlar om vem du är utan även vem du känner. Syfte: Tidigare forskning berättar att personliga kontakter är en av de faktorer som ökar anställningsbarheten. Vi vill därför ta vid där tidigare forskning slutar och göra en mer inriktad studie där vi fokuserar på personliga kontakter och kartlägger dess effekt i praktiken. Vi ämnar därför förklara personliga kontakters betydelse i samband med nyanställning av civilekonomer med examen från 2007-2012. Metod: Vi har valt att genomföra vår studie med en kvantitativ undersökningsdesign och ett deduktivt synsätt på relationen teori och forskning. Empiriska data har insamlats genom enkätundersökning. Slutsats: Vår slutsats är att personliga kontakter är användbara för civilekonomer i anställningsprocessen, att kontakterna till 90,4% leder dem till minst intervju och att kontakterna inte nödvändigtvis är de som är definierade som svaga, se Granovetters (1973, 1975) teorier om The Strength of Weak Ties. / Background: In 2010 SCB presented a survey of how 403 000 jobs were added (GP 2010). 79 000 of these were added through social contacts and another 100 000 by the employer himself who contacted the unemployed. This trend of using social contacts in the job-seeking process gets support by Hensvik, doctor in economics. In the magazine Framtider (2012) she writes that the social environment such as neighbours, class mates, former colleagues and parents have a big impact if we get an employment or not. Hensvik (2012) says that the caring of ones contacts is an important self-investment that improves your probabilities of getting an employment. She continues writing that in today’s society it’s not only important who you are but also who you know. Purpose: Previous research tells that social contacts are one of the factors that will improve your probabilities of getting employed. We will continue where previous research tends to end and aim for a more focused study where we measure the effects of using contacts in reality. The purpose of this thesis is to explain the contacts’ importance when employing former students with a Degree of Master of Science in Business and Economics. Method: We have conducted a questionnaire survey that was sent out to eight Swedish universities resulting in 100 responses. Conclusion: We have come to the conclusion that social contacts contribute in the recruitment process of former business students, that the use of contacts in 90,4% will get you far in the job-seeking process and that the helpful contacts are not necessarily the ones defined as weak ties, of which Granovetter (1973, 1975) would have argued.
532

Introducing weak affinity chromatography to drug discovery with focus on fragment screening

Duong-Thi, Minh-Dao January 2013 (has links)
Fragment-based drug discovery is an emerging process that has gained popularity in recent years. The process starts from small molecules called fragments. One major step in fragment-based drug discovery is fragment screening, which is a strategy to screen libraries of small molecules to find hits. The strategy in theory is more efficient than traditional high-throughput screening that works with larger molecules. As fragments intrinsically possess weak affinity to a target, detection techniques of high sensitivity to affinity are required for fragment screening. Furthermore, the use of different screening methods is necessary to improve the likelihood of success in finding suitable fragments. Since no single method can work for all types of screening, there is a demand for new techniques. The aim of this thesis is to introduce weak affinity chromatography (WAC) as a novel technique for fragment screening. WAC is, as the name suggests, an affinity-based liquid chromatographic technique that separates compounds based on their different weak affinities to an immobilized target. The higher affinity a compound has towards the target, the longer it remains in the separation unit, and this will be expressed as a longer retention time. The affinity measure and ranking of affinity can be achieved by processing the obtained retention times of analyzed compounds. In this thesis, WAC is studied for fragment screening on two platforms. The first system comprised a 24-channel affinity cartridge that works in cooperation with an eight-needle autosampler and 24 parallel UV detector units. The second system was a standard analytical LC-MS platform that is connected to an affinity column, generally called WAC-MS or affinity LC-MS. The evaluation criteria in studying WAC for fragment screening using these platforms were throughput, affinity determination and ranking, specificity, operational platform characteristics and consumption of target protein and sample. The model target proteins were bovine serum albumin for the first platform, thrombin and trypsin for the latter. Screened fragments were either small molecule drugs, a thrombin-directed collection of compounds, or a general-purpose fragment library. To evaluate WAC for early stages of fragment elaboration, diastereomeric mixtures from a thrombin-directed synthesis project were screened. Although both analytical platforms can be used for fragment screening, WAC-MS shows more useful features due to easy access to the screening platform, higher throughput and ability to analyze mixtures. Affinity data from WAC are in good correlation with IC50 values from enzyme assay experiments. The possibility to distinguish specific from non- specific interactions plays an important role in the interpretation of WAC results. In this thesis, this was achieved by inhibiting the active site of the target protein to measure off-site interactions. WAC proves to be a sensitive, robust, moderate in cost and easy to access technique for fragment screening, and can also be useful in the early stages of fragment evolution. In conclusion, this thesis has demonstrated the proof of principle of using WAC as a new tool to monitor affinity and to select hits in fragment-based drug discovery. This thesis has indicated the primary possibilities, advantages as well as the limitations of WAC in fragment screening procedures.  In the future, WAC should be evaluated on other targets and fragment libraries in order to realize more fully the potential of the technology.
533

The Mathematical Theory of Thin Film Evolution

Ulusoy, Suleyman 03 July 2007 (has links)
We try to explain the mathematical theory of thin liquid film evolution. We start with introducing physical processes in which thin film evolution plays an important role. Derivation of the classical thin film equation and existing mathematical theory in the literature are also introduced. To explain the thin film evolution we derive a new family of degenerate parabolic equations. We prove results on existence, uniqueness, long time behavior, regularity and support properties of solutions for this equation. At the end of the thesis we consider the classical thin film Cauchy problem on the whole real line for which we use asymptotic equipartition to show H^1(R) convergence of solutions to the unique self-similar solution.
534

Projection Methods for Variational Inequalities Governed by Inverse Strongly Monotone Operators

Lin, Yen-Ru 26 June 2010 (has links)
Consider the variational inequality (VI) x* ∈C, ‹Fx*, x - x* ›≥0, x∈C (*) where C is a nonempty closed convex subset of a real Hilbert space H and F : C¡÷ H is a monotone operator form C into H. It is known that if F is strongly monotone and Lipschitzian, then VI (*) is equivalently turned into a fixed point problem of a contraction; hence Banach's contraction principle applies. However, in the case where F is inverse strongly monotone, VI (*) is equivalently transformed into a fixed point problem of a nonexpansive mapping. The purpose of this paper is to present some results which apply iterative methods for nonexpansive mappings to solve VI (*). We introduce Mann's algorithm and Halpern's algorithm and prove that the sequences generated by these algorithms converge weakly and respectively, strongly to a solution of VI (*), under appropriate conditions imposed on the parameter sequences in the algorithms.
535

Quasi-Fejer-monotonicity and its applications

Huang, Jun-Hua 05 July 2011 (has links)
Iterative methods are extensively used to solve linear and nonlinear problems arising from both pure and applied sciences, and in particular, in fixed point theory and optimization. An iterative method which is used to find a fixed point of an operator or an optimal solution to an optimization problem generates a sequence in an iterative manner. We are in a hope that this sequence can converge to a solution of the problem under investigation. It is therefore quite naturally to require that the distance of this sequence to the solution set of the problem under investigation be decreasing from iteration to iteration. This is the idea of Fejer-monotonicity. In this paper, We consider quasi-Fejer monotone sequences; that is, we consider Fejer monotone sequences together with errors. Properties of quasi-Fejer monotone sequences are investigated, weak and strong convergence of quasi-Fejer monotone sequences are obtained, and an application to the convex feasibility problem is included.
536

Search for the Decay B0 -> eta phi at the BABAR Experiment / Suche nach dem Zerfall B0 -> eta phi am BABAR-Experiment

Otto, Stephan 09 April 2005 (has links) (PDF)
Presented is a search for the rare hadronic B meson decay B0 -> eta phi. It is based on 86 x 10^6 BB pairs recorded by the BABAR experiment at the Stanford Linear Accelerator Center between 1999 and 2002. phi mesons are reconstructed in the channel phi -> K+ K-. eta mesons are reconstructed in the channels eta -> gamma gamma and eta -> pi+ pi- pi0. Signal events are identified by a candidate counting and a maximum-likelihood method. To ensure an unbiased measurement, the number of signal events is blinded throughout the analysis. Although no significant signal is found by either method, the maximum-likelihood method obtains a smaller statistical uncertainty. In this method, the branching fraction of the decay B0 -> eta phi is determined by the upper limit BR (B0 -> eta phi) < 3.28 x 10^-6 (90%). This value includes a systematic uncertainty of 6.2%. The cited upper limit is consistent with recent theoretical predictions. Therefore, this search gives no indication for particle interactions that are not described by the Standard Model of particle physics. / Vorgestellt wird eine Suche nach dem seltenen hadronischen B-Meson-Zerfall B0 -> eta phi. Sie basiert auf 86 x 10^6 BB-Paaren, die zwischen 1999 und 2002 vom BABAR-Experiment am Stanford Linear Accelerator Center aufgezeichnet wurden. phi-Mesonen werden im Kanal phi -> K+ K- rekonstruiert. eta-Mesonen werden in den Kanälen eta -> gamma gamma und eta -> pi+ pi- pi0 rekonstruiert. Zur Identifikation von Signalereignissen wird eine Abzählmethode und eine Maximum-Likelihood-Methode verwendet. Um eine unvoreingenommene Messung zu gewährleisten, bleibt die Anzahl der Signalereignisse während der gesamten Analyse blind. Durch keine der verwendeten Methoden wird ein signifikantes Signal nachgewiesen. Die Maximum-Likelihood-Methode liefert jedoch eine kleinere statistische Unsicherheit. In dieser Methode ist das Verzweigungsverhältnis des Zerfalls B0 -> eta phi durch die obere Grenze BR (B0 -> eta phi) < 3.28 x 10^-6 (90%) gegeben. Dieser Wert enthält eine systematische Unsicherheit von 6.2%. Die angegebene obere Grenze ist mit aktuellen theoretischen Vorhersagen konsistent. Damit gibt diese Untersuchung keine Hinweise auf Wechselwirkungen, die nicht durch das Standardmodell der Elementarteilchenphysik beschrieben werden.
537

Voltage Source Converters with Energy Storage Capability

Xie, Hailian January 2006 (has links)
<p>This project deals with voltage source converters with energy storage capability. The main objective is to study the possible benefits of energy storage to a power system with a VSC as the interface between them.</p><p>First of all, a converter control system is proposed for a two level VSC. In the conventional converter control, the control system usually takes the voltage measured at the point where the converter is connected and calculates the reference voltage for the converter; with a modulation system the converter then produces the required 'average voltage'. In this project, a novel flux modulation scheme, combined with the deadbeat current control strategy, is proposed. The current controller is capable of controlling both positive and negative sequence current components. With flux modulation, the control system measures the bus flux and commands the converter to generate the required flux.</p><p>Based on the proposed control strategies, several application studies have been carried out.</p><p>The first application study investigates the effect of energy storage on the power quality at the point of common coupling when a system is subject to load disturbances. The voltage at PCC in a weak network is very sensitive to load changes. A sudden change in active load will cause both a phase jump and a magnitude fluctuation in the bus voltage, whereas reactive load changes mainly affect the voltage magnitude. With the addition of energy storage to a StatCom, it is possible to compensate for the active power change as well as providing reactive power support. In this thesis, some effective active power compensation schemes are proposed. Simulations and experiments have been performed to verify the compensation schemes. The results show that a StatCom with energy storage can significantly reduce phase jumps and magnitude deviations of the bus voltage.</p><p>pact of the energy storage on the performance of weak systems under fault conditions has been investigated. The investigation was done by studying an example system. The system model was established based on a real system, in which some induction motors driving pumps along a pipeline are fed from a radial transmission line. Studies show that for a weak system with induction motor loads, a StatCom with certain energy storage capacity will effectively improve the system recovery after faults. Although this incurs extra cost for the increasing dc voltage rating and size of the dc side capacitor, the overall rating of the converter can be reduced by utilization of the proposed active power compensation scheme.</p><p>The last case study investigates the possible use of a StatCom with energy storage to improve the power quality at the point of common coupling where a cyclic load is connected. Studies show that by providing both fast reactive and fast active power support to the network, not only the voltage magnitude can be well controlled, but also the voltage phase jump can be reduced significantly.</p>
538

Strength of Megathrust Faults: Insights from the 2011 M=9 Tohoku-oki Earthquake

Brown, Lonn 27 August 2015 (has links)
The state of stress in forearc regions depends on the balance of two competing factors: the plate coupling force that generates margin-normal compression, and the gravitational force, that generates margin-normal tension. Widespread reversal of the focal mechanisms of small earthquakes after the 2011 Tohoku-oki earthquake indicate a reversal in the dominant state of stress of the forearc, from compressive before the earthquake to tensional afterwards. This implies that the plate coupling force dominated before the earthquake, and that the coseismic weakening of the fault lowered the amount of stress exerted on the forearc, such that the gravitational force became dominant in the post-seismic period. This change requires that the average stress drop along the fault represents a significant portion of the fault strength. Two cases are possible: (1) The fault was strong and the stress drop was large or nearly-complete (e.g. from 50 MPa to 10 MPa), or (2) that the fault was weak and the stress drop was small (e.g. from 15 MPa to 10 MPa). The first option appears to be consistent with the dramatic weakening associated with high-rate rock friction experiments, while the second option is consistent with seismological observations that large earthquakes are characterized by low average stress drops. In this work, we demonstrate that the second option is correct. A very weak fault, represented by an apparent coefficient of friction of 0.032, is sufficient to put the Japan Trench forearc into margin-normal compression. Lowering this value by ~0.01 causes the reversal of the state of stress as observed after the earthquake. A slightly stronger fault, with a strength of 0.045, does not agree well with the observed spatial extent of normal faulting for the same coseismic reduction in strength. We also calculate distributions of stress change on the fault and average stress drop values for the Tohoku-oki earthquake, as predicted from 20 published rupture models which were constrained by seismic, tsunami, and geodetic data. Our results reconcile seismic observations that average stress drops for large megathrust events are low with laboratory work on high-rate weakening that predicts very high or complete stress drop. We find that, in all rupture models, regions of high stress drop (20 – 55 MPa) are probably indicative of dynamic weakening during seismic slip, but that the heterogeneous nature of fault slip does not allow these regions to become widespread. Also, coseismic stress increase on the fault occurs in many parts of the fault, including parts of the area that experienced high slip (> 30 m). These two factors ensure that the average stress drop remains low (< 5 MPa). The low average stress drop during the Tohoku earthquake, consistent with values reported for other large earthquakes, makes it unambiguous that the Japan Trench megathrust is very weak. / Graduate
539

Vinylsqueegee.com : a community to enrich the landscape of music culture through an historical perspective

Fitzgerald, Anna Marie 21 February 2011 (has links)
This report chronicles the process of investigating social theories and their relation to music experience in order to create a specific online community. The purpose of this community focuses on an historical perspective of music while facilitating the formation of varied knowledge-networks and relationship levels. Social theories are correlated with web applications and tools to support design choices that will appeal to users by providing opportunities for specific social functions. This research allows for an organized, detailed, and theoretical approach to the design of the online music community, Vinylsqueegee.com. / text
540

Elektronenspinresonanz in Systemen mit ferromagnetischen Korrelationen

Förster, Tobias 12 December 2013 (has links) (PDF)
Die Arbeit befasst sich mit der Elektronenspinresonanz (ESR) stark korrelierter Elektronensysteme mit ferromagnetischen Wechselwirkungen. Es wurden dafür Messungen an den Kondogitter-Systemen CeRuPO und CeOsPO, der Dotierungsreihe CeFeAs1-xPxO, den niederdimensionalen frustrierten Quadratgittern AA’VO(PO4)2 sowie in dem schwach ferromagnetischen Metall Nb1-yFe2+y durchgeführt. Alle Verbindungen zeigen entweder eine ferromagnetische Ordnung oder befinden sich in der Nähe einer ferromagnetischen Instabilität, die die Eigenschaften des stark korrelierten Systems beeinflusst.

Page generated in 0.0646 seconds