• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 208
  • 63
  • 30
  • 14
  • 8
  • 7
  • 5
  • 5
  • 4
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 397
  • 397
  • 76
  • 52
  • 44
  • 44
  • 43
  • 32
  • 32
  • 32
  • 28
  • 27
  • 25
  • 25
  • 24
  • 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.
261

Construction and analysis of efficient numerical methods to solve Mathematical models of TB and HIV co-infection

Ahmed, Hasim Abdalla Obaid. January 2011 (has links)
In this thesis, we study these models and design and analyze robust numerical methods to solve them. To proceed in this direction, first we study the sub-models and then the full model. The first sub-model describes the transmission dynamics of HIV that accounts for behavior change. The impact of HIV educational campaigns is also studied. Further, we explore the effects of behavior change and different responses of individuals to educational campaigns in a situation where individuals may not react immediately to these campaigns. This is done by considering a distributed time delay in the HIV sub-model. This leads to Hopf bifurcations around the endemic equilibria of the model. These bifurcations correspond to the existence of periodic solutions that oscillate around the equilibria at given thresholds. Further, we show how the delay can result in more HIV infections causing more increase in the HIV prevalence. Part of this study is then extended to study a co-infection model of HIV-TB. A thorough bifurcation analysis is carried out for this model. Robust numerical methods are then designed and analyzed for these models. Comparative numerical results are also provided for each model.
262

The University; A Learning Organization? : An Illuminative Review Based on System Theory

Strandli Portfelt, I January 2006 (has links)
There are voices in the research field suggesting that universities should become learning organisations in order to be more competitive and efficient. However, the proposal is mainly based on theoretical and normative discussions rather than on empirical research. Therefore, this study has explored and reviewed in what way a university organisation has organised its inner life and illuminate in what way its local organisation matches the characteristics of a constructed theoretical model of a learning organisation. The study has furthermore explored in what way the organisational characteristics interact with one another in order to find out whether they support or hinder organisational learning.
263

Solidaritetens omvägar. : (LM) Ericsson, svenska Metall och Ericssonarbetarna i Colombia 1973-1993

Sjölander, Jonas January 2005 (has links)
This study deals with the historical compromise between Labour and Capital—the so-called “Swedish model”—and the abandonment of this compromise in connection with the third industrial revolution. The focus of the study lies in the transformations in working life and labour internationalism from 1973 to 1993. The strategies of the trade union regarding the protection of workers’ rights at local, national and international levels are of particular interest. The relations between the Company Union Group at LM Ericsson, the Swedish Metalworkers’ Federation and the local union at Ericsson’s work premises in Colombia (Sintraericsson) are examined in depth. The research is conducted through archive studies and interviews according to oral history theories. The theoretical perspectives in the dissertation are mainly inspired by postcolonial and materialist world system theories. The examined relations took place in a time that from the point of view of the trade union was characterized by uncertainty and anxiety about the future. The visible effects of the technological and industrial processes of transformation in Sweden as well as in Colombia had increased, and one of the main manifestations of the changes was the decreasing demand of manual labour. The introduction of the electronic AXE-system at LM Ericsson industries constituted a significant pass toward increasingly minimized and decreasing labour-intensive telecommunication systems. In Colombia, the local management took advantage of both the political unrest and instability and the absence of functional legislation praxis of work in order to set back and, finally, repudiate Sintraericsson. Many obstacles were mounted impeding the realization of collected and vigorous international labour actions which, had these been successful, would have constituted a response to the union-hostile actions initiated by the company. The Swedish Metalworkers’ Federation and the Company Union Group at LM Ericsson in Sweden were faced with several strategical and ideological issues resulting in their support of Sintraericsson appearing as obligatory or even absent. The study further shows that LM Ericsson as a company had advantages when compared with the Labour Organizations in Sweden and Colombia. The company early established business connections in Colombia and had knowledge about, and was an active part of, the Colombian society. The company was not driven by moral principles though it on the one hand could point at Colombian laws and norms, and on the other hand at overreaching economical “laws” when it came to motivating the politics vis-à-vis the employees, the local union and the frequent dismissals of union activists at Ericsson de Colombia.
264

Gränsöverskridande val och vägledning : En studie om studievägledning och breddad rekrytering inom högskola/universitet / Choices beyond the norms and student couselling

Rönn, Britt Marie January 2009 (has links)
Sammanfattning Syftet med denna uppsats var att ge en bild av hur ett antal studie- och karriärvägledare inom universitet/högskola förhåller sig till begreppet breddad rekrytering. Uppsatsen ville också visa vad en högskola och ett universitet har för strategier för att bredda sin rekrytering och om man medvetet använder sig av studie- och karriärvägledning för detta ändamål. Metoden var kvalitativ och resultaten byggde på intervjuer av tio studievägledare fördelade på en högskola och ett universitet, samt två personer som arbetar övergripande med breddad rekrytering på dessa lärosäten. Det som framkom är att studievägledarna överlag anser att breddad rekrytering är en viktig uppgift som ingår i deras yrkesverksamhet, vidare att vägledningen är mer psykologiskt än socialt inriktad, på så sätt att vägledarna fokuserar mer på psykologiska aspekter som t ex studentens intressen, värderingar och förmågor snarare än den sociala kontext studenten befinner sig i t ex klasstillhörighet eller genus. Det finns inslag av processtänkande men fortfarande mycket av "trait and factor" tänkande. Högskolan/ universitetet anser att studievägledning är en viktig verksamhet och använder sig delvis av den för att bredda sin rekrytering, men kunskapen om vad vägledning är och kan användas till känns delvis outvecklad. En framtidsvision är att vägledning har mer av samhällsförbättrande karaktär. Vägledaren skulle då vara en person som uppmuntrar till val utanför normen: Gränsöverskridande val. / Abstract The purpose of this thesis was to give a picture of how a number of student counsellors at the university look on their commission in the perspective of widening recruitment. The thesis also showed what strategies the universities have to widen their recruitment and of how to use counselling for this purpose. The method was qualitative and the result was founded on interviews with ten student counsellors from two different universities and from two persons who work overall with widening recruitment and diversity. This study shows that student counsellors regard widening recruitment as an important task in their work. It emerged under the interviews that counselling is more psychological than social, which means that the counsellors focus more on factors like interests, values and competence rather than social context with factors like social class and gender. There are elements of trait and factor thinking as well as a great deal of process thinking. The university regards student counselling as an important activity and is using it for widening recruitment, but the knowledge of  it and its use is somewhat undeveloped. A vision for the future is that the counsellor has more the task of a social reformer. The counsellor would then be the one who encourages the student for choices beyond the norms.
265

Robust inference of gene regulatory networks : System properties, variable selection, subnetworks, and design of experiments

Nordling, Torbjörn E. M. January 2013 (has links)
In this thesis, inference of biological networks from in vivo data generated by perturbation experiments is considered, i.e. deduction of causal interactions that exist among the observed variables. Knowledge of such regulatory influences is essential in biology. A system property–interampatteness–is introduced that explains why the variation in existing gene expression data is concentrated to a few “characteristic modes” or “eigengenes”, and why previously inferred models have a large number of false positive and false negative links. An interampatte system is characterized by strong INTERactions enabling simultaneous AMPlification and ATTEnuation of different signals and we show that perturbation of individual state variables, e.g. genes, typically leads to ill-conditioned data with both characteristic and weak modes. The weak modes are typically dominated by measurement noise due to poor excitation and their existence hampers network reconstruction. The excitation problem is solved by iterative design of correlated multi-gene perturbation experiments that counteract the intrinsic signal attenuation of the system. The next perturbation should be designed such that the expected response practically spans an additional dimension of the state space. The proposed design is numerically demonstrated for the Snf1 signalling pathway in S. cerevisiae. The impact of unperturbed and unobserved latent state variables, that exist in any real biological system, on the inferred network and required set-up of the experiments for network inference is analysed. Their existence implies that a subnetwork of pseudo-direct causal regulatory influences, accounting for all environmental effects, in general is inferred. In principle, the number of latent states and different paths between the nodes of the network can be estimated, but their identity cannot be determined unless they are observed or perturbed directly. Network inference is recognized as a variable/model selection problem and solved by considering all possible models of a specified class that can explain the data at a desired significance level, and by classifying only the links present in all of these models as existing. As shown, these links can be determined without any parameter estimation by reformulating the variable selection problem as a robust rank problem. Solution of the rank problem enable assignment of confidence to individual interactions, without resorting to any approximation or asymptotic results. This is demonstrated by reverse engineering of the synthetic IRMA gene regulatory network from published data. A previously unknown activation of transcription of SWI5 by CBF1 in the IRMA strain of S. cerevisiae is proven to exist, which serves to illustrate that even the accumulated knowledge of well studied genes is incomplete. / Denna avhandling behandlar inferens av biologiskanätverk från in vivo data genererat genom störningsexperiment, d.v.s. bestämning av kausala kopplingar som existerar mellan de observerade variablerna. Kunskap om dessa regulatoriska influenser är väsentlig för biologisk förståelse. En system egenskap—förstärksvagning—introduceras. Denna förklarar varför variationen i existerande genexpressionsdata är koncentrerat till några få ”karakteristiska moder” eller ”egengener” och varför de modeller som konstruerats innan innehåller många falska positiva och falska negativa linkar. Ett system med förstärksvagning karakteriseras av starka kopplingar som möjliggör simultan FÖRSTÄRKning och förSVAGNING av olika signaler. Vi demonstrerar att störning av individuella tillståndsvariabler, t.ex. gener, typiskt leder till illakonditionerat data med både karakteristiska och svaga moder. De svaga moderna domineras typiskt av mätbrus p.g.a. dålig excitering och försvårar rekonstruktion av nätverket. Excitationsproblemet löses med iterativdesign av experiment där korrelerade störningar i multipla gener motverkar systemets inneboende försvagning av signaller. Följande störning bör designas så att det förväntade svaret praktiskt spänner ytterligare en dimension av tillståndsrummet. Den föreslagna designen demonstreras numeriskt för Snf1 signalleringsvägen i S. cerevisiae. Påverkan av ostörda och icke observerade latenta tillståndsvariabler, som existerar i varje verkligt biologiskt system, på konstruerade nätverk och planeringen av experiment för nätverksinferens analyseras. Existens av dessa tillståndsvariabler innebär att delnätverk med pseudo-direkta regulatoriska influenser, som kompenserar för miljöeffekter, generellt bestäms. I princip så kan antalet latenta tillstånd och alternativa vägar mellan noder i nätverket bestämmas, men deras identitet kan ej bestämmas om de inte direkt observeras eller störs. Nätverksinferens behandlas som ett variabel-/modelselektionsproblem och löses genom att undersöka alla modeller inom en vald klass som kan förklara datat på den önskade signifikansnivån, samt klassificera endast linkar som är närvarande i alla dessa modeller som existerande. Dessa linkar kan bestämmas utan estimering av parametrar genom att skriva om variabelselektionsproblemet som ett robustrangproblem. Lösning av rangproblemet möjliggör att statistisk konfidens kan tillskrivas individuella linkar utan approximationer eller asymptotiska betraktningar. Detta demonstreras genom rekonstruktion av det syntetiska IRMA genreglernätverket från publicerat data. En tidigare okänd aktivering av transkription av SWI5 av CBF1 i IRMA stammen av S. cerevisiae bevisas. Detta illustrerar att t.o.m. den ackumulerade kunskapen om välstuderade gener är ofullständig. / <p>QC 20130508</p>
266

Construction and analysis of efficient numerical methods to solve mathematical models of TB and HIV co-infection

Ahmed, Hasim Abdalla Obaid January 2011 (has links)
<p>The global impact of the converging dual epidemics of tuberculosis (TB) and human immunodeficiency virus (HIV) is one of the major public health challenges of our time, because in many countries, human immunodeficiency virus (HIV) and mycobacterium tuberculosis (TB) are among the leading causes of morbidity and mortality. It is found that infection with HIV increases the risk of reactivating latent TB infection, and HIV-infected individuals who acquire new TB infections have high rates of disease progression. Research has shown that these two diseases are enormous public health burden, and unfortunately, not much has been done in terms of modeling the dynamics of HIV-TB co-infection at a population level. In this thesis, we study these models and design and analyze robust numerical methods to solve them. To proceed in this direction, first we study the sub-models and then the full model. The first sub-model describes the transmission dynamics of HIV that accounts for behavior change. The impact of HIV educational campaigns is also studied. Further, we explore the effects of behavior change and different responses of individuals to educational campaigns in a situation where individuals may not react immediately to these campaigns. This is done by considering a distributed time delay in the HIV sub-model. This leads to Hopf bifurcations around the endemic equilibria of the model. These bifurcations correspond to the existence of periodic solutions that oscillate around the equilibria at given thresholds. Further, we show how the delay can result in more HIV infections causing more increase in the HIV prevalence. Part of this study is then extended to study a co-infection model of HIV-TB. A thorough bifurcation analysis is carried out for this model. Robust numerical methods are then designed and analyzed for these models.&nbsp / Comparative numerical results are also provided for each model.</p>
267

Avhopp inom 12-stgsbehandling : En studie om vilka faktorer som finns till klienters avhopp inom 12-stegsbehandling och eventuella skillnader mellan könen.

Ferm, Anita, Josefsson, Sanna January 2011 (has links)
No description available.
268

Du sköna fria värld : En analys av globaliseringsdebatten utifrån ett makt- och hegemoniperspektiv

Ernestrand, Henrik January 2012 (has links)
This essay aims to emphasize and clarify the positions that exist within the current globalization debate. The positions are the neo-liberal, the opponents, the pragmatists and the skeptics. The text presents and explains their ideological, moral and political positions and beliefs about the world, the nation state, the society and the individual; in light of Steven Lukes’ and Antonio Gramsci's theories regarding the interaction and the relationship between power and hegemony. The methodological starting point is the ideology-critical analysis; in which their arguments in the current globalization debate is highlighted and categorized. The neo-liberals consider globalization as a tool to legitimize the notion of the free, rational and autonomous individual – who in a free market chooses to contract, interact and relate to each other without facing any government intervention. Opponents see that globalization does not necessarily have to mean the spread of neoliberal economic doctrines – or government deregulation or privatization – but instead may represent a path towards a more just, democratic and inclusive world. Between these two diametrically opposed positions are the pragmatists; who argue that there must be a balance between political and economic freedom and government regulation and their institutional powers. Only then will globalization have the desired effects needed to be able to lift nations out of poverty, bring well being and evoke a greater temporal coherence at the global level. Finally, the skeptics’ viewpoint is that the concept of globalization is misleading and is used mainly as a diversion to hide the real interests – namely the U.S. ambitions to maintain its hegemonic position to continue to spread their neo-liberal ideology through the principles of free trade and democratization through the abolition of the welfare state. The analysis shows that the globalization debate is not primarily about what arguments are discussed at the present time, but instead deals with the political and ideological beliefs concerning how society should be designed and how the world should be comprehended and understood. The globalization debate is really about the individual and collective consciousness created by the liberal hegemonic exercise of power, and how this influence is manifested through the intellectual and moral leadership of the ruling class in the world today.
269

Distributed learning in large populations

Fox, Michael Jacob 14 August 2012 (has links)
Distributed learning is the iterative process of decision-making in the presence of other decision-makers. In recent years, researchers across fields as disparate as engineering, biology, and economics have identified mathematically congruous problem formulations at the intersection of their disciplines. In particular, stochastic processes, game theory, and control theory have been brought to bare on certain very basic and universal questions. What sort of environments are conducive to distributed learning? Are there any generic algorithms offering non-trivial performance guarantees for a large class of models? The first half of this thesis makes contributions to two particular problems in distributed learning, self-assembly and language. Self-assembly refers to the emergence of high-level structures via the aggregate behavior of simpler building blocks. A number of algorithms have been suggested that are capable of generic self-assembly of graphs. That is, given a description of the objective they produce a policy with a corresponding performance guarantee. These guarantees have been in the form of deterministic convergence results. We introduce the notion of stochastic stability to the self-assembly problem. The stochastically stable states are the configurations the system spends almost all of its time in as a noise parameter is taken to zero. We show that in this framework simple procedures exist that are capable of self-assembly of any tree under stringent locality constraints. Our procedure gives an asymptotically maximum yield of target assemblies while obeying communication and reversibility constraints. We also present a slightly more sophisticated algorithm that guarantees maximum yields for any problem size. The latter algorithm utilizes a somewhat more presumptive notion of agents' internal states. While it is unknown whether an algorithm providing maximum yields subject to our constraints can depend only on the more parsimonious form of internal state, we are able to show that such an algorithm would not be able to possess a unique completing rule--- a useful feature for analysis. We then turn our attention to the problem of distributed learning of communication protocols, or, language. Recent results for signaling game models establish the non-negligible possibility of convergence, under distributed learning, to states of unbounded efficiency loss. We provide a tight lower bound on efficiency and discuss its implications. Moreover, motivated by the empirical phenomenon of linguistic drift, we study the signaling game under stochastic evolutionary dynamics. We again make use of stochastic stability analysis and show that the long-run distribution of states has support limited to the efficient communication systems. We find that this behavior is insensitive to the particular choice of evolutionary dynamic, a fact that is intuitively captured by the game's potential function corresponding to average fitness. Consequently, the model supports conclusions similar to those found in the literature on language competition. That is, we expect monomorphic language states to eventually predominate. Homophily has been identified as a feature that potentially stabilizes diverse linguistic communities. We find that incorporating homophily in our stochastic model gives mixed results. While the monomorphic prediction holds in the small noise limit, diversity can persist at higher noise levels or as a metastable phenomenon. The contributions of the second half of this thesis relate to more basic issues in distributed learning. In particular, we provide new results on the problem of distributed convergence to Nash equilibrium in finite games. A recently proposed class of games known as stable games have the attractive property of admitting global convergence to equilibria under many learning dynamics. We show that stable games can be formulated as passive input-output systems. This observation enables us to identify passivity of a learning dynamic as a sufficient condition for global convergence in stable games. Notably, dynamics satisfying our condition need not exhibit positive correlation between the payoffs and their directions of motion. We show that our condition is satisfied by the dynamics known to exhibit global convergence in stable games. We give a decision-theoretic interpretation for passive learning dynamics that mirrors the interpretation of stable games as strategic environments exhibiting self-defeating externalities. Moreover, we exploit the flexibility of the passivity condition to study the impact of applying various forecasting heuristics to the payoffs used in the learning process. Finally, we show how passivity can be used to identify strategic tendencies of the players that allow for convergence in the presence of information lags of arbitrary duration in some games.
270

Approaches to energy efficient building development : studying under Chinese contexts

Gu, Zhenhong January 2007 (has links)
<p>This thesis presents a general description of approaches to energy efficient building development under Chinese contexts. The purpose of the work is to discuss how Chinese building development can be approved from an energy saving perspective.</p><p>Building development is a complicated process that relates to many stakeholders’ interests. The developed countries have studied in this field extensively for several decades. Generally, the approaches to energy saving can be set at three levels: administration, construction industry and architectural design. More new strict codes for energy efficient buildings are being issued for enforcement. At the same time, many research institutes have developed Building Environmental Assessment (BEA) methods, where energy efficiency is an important factor in the models. Various technical solutions for energy efficiency are developed as well.</p><p>The administrative approaches are not the main objective discussed in the thesis, though the importance of them is undeniable. BEA systems are not only assessment methods, but also market-based stimulating approaches for sustainability of construction market. Technical methods have been developed for a long period. Passive House and Low Exergy (LowEx) Systems are two representative examples in European countries.</p><p>All of these approaches are relatively unfamiliar to Chinese architects and developers, let alone their effect and applicability. The thesis tries to analyse this situation and their applicability within Chinese context.</p><p>In China to a certain project, the importance of technical issues is relatively recognized. However, a few successful individual cases in technique can not change the reality that most of new building development has failed in energy efficiency in China. This is a serious situation when China is in an enormous expansion phase in building new houses. The thesis tries to discuss the reasons for this phenomenon. One reason could be that the stakeholders in the developing process are not aware of the importance of collaboration which is the only method to get “Both Win” according to Game theory. The thesis discusses a paradigm to replace two traditional linear paradigms in building developing process. Architects should act as coordinators of different stakeholders rather than technical supporters.</p><p>The thesis tries to discuss the propositional route of developing energy efficient buildings. Technical approaches are basic research, which presents the concepts that have been proved realizable; BEA encourages developers to develop more energy efficient buildings for economic benefit, which will make good demonstrations for whole market; national laws and policies are final approaches, which ensure that every project will have good performance of energy efficiency. When the old standardization and legislation are finished, a new cycle will begin with more advanced techniques.</p><p>China government has started the progress to enhance energy efficiency. However, this process will be tough and slow. The thesis discusses Chinese special conditions and the problems that cry out for solution in the future.</p>

Page generated in 0.4663 seconds