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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.
1

Binding of visual features in human perception and memory

Jaswal, Snehlata January 2010 (has links)
The leit motif of this thesis is that binding of visual features is a process that begins with input of stimulation and ends with the emergence of an object in working memory so that it can be further manipulated for higher cognitive processes. The primary focus was on the binding process from 0 to 2500 ms, with stimuli defined by location, colour, and shape. The initial experiments explored the relative role of topdown and bottom-up factors. Task relevance was compared by asking participants to detect swaps in bindings of two features whilst the third was either unchanged, or made irrelevant by randomization from study to test, in a change detection task. The experiments also studied the differences among the three defining features across experiments where each feature was randomized, whilst the binding between the other two was tested. Results showed that though features were processed to different time scales, they were treated in the same way by Visual Working Memory processes. Relevant features were consolidated and irrelevant features were inhibited. Later experiments confirmed that consolidation was aided by iconic memory and the inhibitory process was primarily a post-perceptual active inhibition.
2

Kartläggning av Top down och Bottom up i tre fallföretag : Informationsstrategier

Muhsin, Ali, Rusevski, Nikola January 2019 (has links)
Purpose – The purpose of the study is to map out the top-down and bottom-up perspectives and investigate the information strategies on how it relates to daily operations in three case companies. To fulfill the purpose, the following three questions have been answered:   What approach do the organization have on information strategies and what  characterizes them? To what extent do the case organization use the information strategies?   What opportunities and difficulties do organizations see with the information strategies?   Method – To fulfill the purpose, a case study was carried out on three case companies. The empirical data has been collected through interviews and surveys. The theoretical framework together with the empirical data, has then contributed to achieving the purpose.   Findings – First the map out was conducted within three case companies and how the information strategies have been chosen in relation to the daily operations perspective. Based on the mapping, it has then been framed the potential possibilities and difficulties with the respective strategy choices and its implementation. Limitations – The definition of the information strategies within the study is defined as Top-down and Bottom-up and how the choice in how companies choose to coordinate and be responsible for tasks. The authors do not know whether the study can be adapted to the business of other organisations when mapping information strategies.   Keywords – information strategies, top-down, bottom-up, information flow, communication.
3

Translation of Heterogeneous High-level Models to Lower Level Design Languages

Jackson, Brian Aliston 04 May 2005 (has links)
Proceeding from a specification, one develops an abstract mathematical model of a system, or portion of a system. This model of a system is validated to insure that the specification is interpreted accurately and to explore different algorithms for implementing the system behavior. We use the words "portion of a system," because only rarely are systems designed wholly using a purely top-down approach. Commonly, the design approach is a mixture of top-down and bottom-up. But even in this mixed approach, top-down techniques are critical to the development of new, advanced system features and improving the performance of existing system components. An example of this style of design tools and environments is Ptolemy II. Ptolemy II is a high-level modeling tool created at UC-Berkeley. It supports heterogeneous and homogeneous modeling, simulation, and design of concurrent systems. High-level modeling of such embedded systems as digital electronics, hardware, and software can be effectively represented. The bottom-up design approach exploits design reuse to achieve the productivity necessary to build complex systems. Historically, chip design companies have always reused designs in going from one product generation to another, but the efficiency of bottom-up design is enhanced by the use of IP (Intellectual Property) cores that a company can buy from an outside source. Design libraries are useful for system design and are an example of IP cores. A sound methodology to translate Ptolemy models to SystemC models would have a very beneficial effect on the CAD/EDA industry. Ptolemy II is written in Java and its high-level designs, or abstract graph models, are represented as XML documents. Ptolemy's major emphasis is on the methodology for defining and producing embedded software together with the system in which it is embedded. SystemC is written in C++, and its industrial use is gaining momentum due to its ability to represent functionality, communication, software, and hardware at various levels of abstraction. SystemC produces synthesizable code. A methodology to convert Ptolemy models to synthesizable SystemC code would be the technical epitome of a hybrid between top-down and bottom-up design styles and methodologies. Such a methodology would enable system designers to obtain fast design exploration, efficient IP-reuse, and validation. Ptolemy has various components and models of computation. A model of computation dictates how components interact between other components. SystemC has its own models of computation and design libraries. XML and Perl are both powerful tools by themselves, and we use these tools in this research to create a sound methodology for translating Ptolemy models (high-level of abstraction) to synthesizable SystemC code (low-level of abstraction), i.e.: code which can serve as input to hardware tools. / Ph. D.
4

Från top down till bottom up : - Att förklara och utvärdera psykosocialt arbete inom hälso- och sjukvården

Landpers, Håkan January 2010 (has links)
Today, activities funded with public funds needs to present relevant and reliable information which shows the results obtained. Requirements increase in welfare activities to be run based on scientific, empirical knowledge. This applies particularly to social work. The social work is, however, poorly researched in areas such as knowledge of interventions in the content, context and effects. One way to evidence-base social work can be to conduct regular and qualified assessments. To evaluate, however, is complex, and knowledge of the evaluations are deficient in those who plan and execute them. The overall aim of this study was to conduct a systematic literature review to identify key evaluation models to the psychosocial work in health care services. A further aim was to develop an evaluation design for the psychosocial work of kuratorsenheten, Falun Hospital. The evaluation models are presented in the paper based on categories of “top down” and “bottom up ", and" other models ". With the help of some key concepts for the evaluation of social work, the conclusion of the meta-theory of critical realism, conducted the study analysis. The results show that the models relevant to the evaluation of psychosocial work in the health services are mainly oriented towards a bottom up perspective. The models are process evaluations, user-oriented models, stakeholder assessments, self assessments, and goals - performance evaluations. The evaluation design of kuratorsenheten also presents a number of elements in the psychosocial work which is central to document, for the opportunity to explain, evaluate and develop the business forward.
5

Sport and the multisectoral approach to HIV/AIDS in Zambia

Banda, Davies January 2013 (has links)
Sport is increasingly being recognised for the contribution it can make to the Millennium Development Goals and, in particular, the response to the HIV/AIDS pandemic. This study is based on Zambia, a low-income country, heavily affected by the HIV/AIDS pandemic in sub-Saharan Africa. The study focuses on National Sports Associations (NSAs), which are quasi- autonomous organisations at meso level of policy analysis. Centring on three NSAs: Football Association of Zambia (FAZ), Zambia Basketball Association (ZBA) and Netball Association of Zambia (NAZ), this study critically analysed the organisational responses of each of the selected cases towards the HIV/AIDS multisectoral approach. The study adopted a case study approach which utilised semi-structured (face-to-face and telephone), interviews, focus group discussions and documentary analysis for data collection. Comparative analysis of all three cases revealed differences in how each case mainstreamed HIV/AIDS based on power, resources and forms of collaboration. Meso-level analysis was utilised to examine workplace HIV/AIDS policy formulation and implementation. In addition, meso-level analysis also helped reveal forms of health-related collaborations with both internal and external agencies. Macro-level theories of the state were useful in examining power relations between the Zambian state and civil society. The application of policy network theory, global health governance, multiple streams framework, and the top-down and bottom-up approaches to policy implementation proved useful in drawing attention to how each NSA case responded differently to the mainstreaming of HIV/AIDS. The political power of football as a national sport and the Association s access to foreign resources enabled FAZ to influence HIV/AIDS policy implementation and build of strong collaborative relationships with government than the ZBA and NAZ. The study concludes that lack of political steer from the top has re-introduced a new foreign top-down approach as those with resources from the Global North influenced policy formulation and implementation within all three cases. The conclusion also found useful the application of post-colonialism and development theories when examining international sport-for-development practices. This finding revealed the power imbalances between Global South practitioners and Global North funding partners.
6

Impacts Of Nutrients On Periphyton Growth And Periphyton-macroinvertebrates Interactions In Shallow Lakes: A Mesocosm Experiment

Filiz, Nur 01 October 2012 (has links) (PDF)
Periphyton biomass on artificial strips was observed monthly to see the impacts of nutrient differences on periphyton and periphyton-macroinvertebrates interaction. The experiment was conducted for four months in a mesocosm which were runned at six countries at the same time and with the same steps. Eight enclosures at two meters depth were used that four of them had high nutrient level and the other four had low nutrient level. Sediment, macrophyte, fish, plankton, benthic invertebrates and water were added at the same time and with the same way in all of the countries. Periphyton growth which formed on artificial 32 cm2 strips for June, July, August and September were brushed to filtered mesocosm water and dry mass, ash free dry mass, phosphorus content and chlorophyl-a concentrations were measured. Grazer pressure on the periphyton was observed with a laboratory experiment for July, August and September months. At the end of the mesocosm experiment macrophytes and fish were harvested. Macrophytes&rsquo / dry mass and fish&rsquo / abundance were measured. Moreover at the end of the experiment epiphyton was also measured. Three kajak cores were taken from sediment for macroinvertebrates at the end of the experiment and identified. All physical features of mesocosm enclosures and PVI data were recorded for every 2 weeks. Periphyton biomass was higher concentrations in HN enclosures than LN tanks. Only dry mass of periphyton biomass showed the opposite because of the marl deposition in LN tanks. This finding was also reinforced by epiphyton samples which was taken at the end of the experiment. LN enclosures had the more abundance of macroinvertebrate. The groups we found in sediment which had big grazer effect on periphyton such as gastropods and Chironomidae. Grazer experiment showed that grazer effect on periphyton increased in time. Although this raise, periphyton growth also increased in LN enclosures with nutrient increasing. This may be indicate that nutrient effect has a stronger effect than grazer pressure on periphyton. As it is explained before in the beginning of the experiment all of the conditions were the same except nutrient level. Thus, bottom-up effect changed the top-down control and at the end of the experiment we saw the more periphyton less macroinvertebrate and more fish in HN tanks while the opposite was seen in LN tanks.
7

An fMRI Study on Context‐Dependent Processing of Natural Visual Scenes

Petzold, Antje 03 January 2006 (has links)
Visual attention can be voluntarily focused on a location or automatically attracted by salient features in a visual scene. Studies using functional Magnetic Resonance Imaging (fMRI) suggest two networks of visual attention involved in these complementary mechanisms: a dorsal frontoparietal network and a ventral frontoparietal network of visuospatial attention respectively. However, most studies so far have applied non‐natural schematic stimuli. The present study investigates visual attention in images of natural environmental scenes. Adopting previously used eye‐tracker paradigms, we study the influence of task instruction and luminance contrast modifications in pictures on both eye movements and neural activity using Eye‐Tracking and functional Magnetic Resonance Imaging simultaneously. We expect increased top‐down control of attention in a search task compared to a free viewing condition visible in enhanced neural activation in the intraparietal sulcus (IPS) as part of the dorsal frontoparietal network. Strong modifications of luminance contrast should foster bottom‐up processing activating the temporoparietal junction (TPJ) a crucial area in the ventral frontoparietal network of visual attention. Although the obtained eye‐tracking data shows the expected shift of fixations towards locations of increased luminance contrast, we do not find an influence of luminance contrast modifications on neural processing. Comparison of instructions reveals diverse results across participants possibly due to the long presentation duration of stimuli which allowed participant’s attention to wander independently of task instruction. We find bilateral activation in IPS and parahippocampal place area (PPA) as well as bilateral deactivation in the TPJ region independent of task context. This might indicate similar contributions of these areas to free viewing of and search in visual scenes. However, dissociation of target detection and attention during search by deconvolution analysis of data obtained in this study might reveal a more detailed picture of functional involvement of the IPS and TPJ region in processes of visual attention. Remarkably, results show robust activation of the PPA in both tasks, suggesting that the PPA region might not only be activated by houses and open scenes but by narrow scenes (bushes, leaves) of natural outdoor environment as well.
8

Une démarche top-down / bottom-up pour l'évaluation en termes multicritères et multi-acteurs des projets miniers dans l'optique du développement durable. Application sur les mines d'Uranium d'Arlit (Niger)

Chamaret, Aurélie 28 June 2007 (has links) (PDF)
Cette thèse a pour objectif d'éprouver la pertinence d'une approche hybride top-down / bottom-up pour évaluer les projets miniers dans l'optique du développement durable. Avec l'avènement des concepts de responsabilité sociale d'entreprise et de développement durable, de nouvelles attentes sociétales pèsent en effet sur les entreprises qui vont au-delà d'une simple exigence de rentabilité économique. Des réponses doivent être apportées par les entreprises, au risque de perdre leur légitimité sociale. Traditionnellement associée à des risques et des impacts sociaux, environnementaux, économiques et politiques jugés traditionnellement comme importants, l'activité minière est particulièrement concernée par ces nouveaux enjeux. Alors que les besoins en ressources minérales n'ont jamais été aussi élevés, on attend désormais des entreprises qu'elles limitent leurs effets négatifs et prennent en compte les préoccupations de leurs différents publics afin de définir ensemble les termes d'un accord conférant à l'entreprise sa légitimité. Au vu de la diversité des enjeux, des échelles, des contextes et des acteurs concernés, le défi est de taille et nécessite des outils visant à mieux cerner les enjeux et structurer les dialogues. Basé sur l'étude de cas des mines d'uranium d'Arlit au Niger, ce travail montre qu'associer des démarches participatives à des outils de structuration et des propositions issus de la littérature apparaît comme une formule efficace pour mieux organiser la diversité des enjeux associés au projet et construire une négociation structurée entre les entreprises minières et leurs parties prenantes. La Première Partie, (Cadrages), a pour objectif de présenter les contextes théoriques, institutionnels et sectoriels dans lesquels s'ancre la thèse. La Deuxième Partie, (Application de la démarche sur les mines d'Arlit), expose les travaux et les résultats de l'évaluation réalisée au Niger. Enfin, la Troisième Partie, (Recadrages), dresse le bilan des enseignements et des conclusions que l'on peut tirer de ce travail de recherche et présente une proposition de démarche potentiellement applicable à d'autres sites miniers.
9

Bottom-Up Controls (Micronutrients and N and P Species) Better Predict Cyanobacterial Abundances in Harmful Algal Blooms Than Top-Down Controls (Grazers)

Collins, Scott Andrew 01 July 2019 (has links)
The initiation, bloom, and bust of harmful Cyanobacteria and algae blooms (HAB) in lakes are controlled by top-down and bottom-up ecological controls. Excess phosphorous and nitrogen inputs from anthropogenic sources are primary to blame, but eukaryotic grazers may also promote or curb Cyanobacteria dominance. We tracked shifts in bacterial composition, lake chemistry, and eukaryotic grazing community weekly or bi-weekly through spring and summer and modeled the causes of specific Cyanobacterial species blooms and busts across three lakes in Utah, USA, with differing lake trophic states. Regardless of trophic status, all three lakes experienced blooms of varying composition and duration. Aphanizomenon strain MDT14a was the most dominant species in every bloom on Utah Lake, comprising up to 44.16% of the bacterial community. Utah Lake experienced a total of 18 blooms across all sites ranging in duration from one to six weeks. Phormidiaceae sp. (8.5  6.1%) and Microcystis sp. (9.7  4.7%) were the most abundant species in the Deer Creek bloom. Deer creek experienced one bloom at the beginning of fall. Nodularia sp. (9.7  2.1) dominated Great Salt Lake bloom. The Great Salt Lake experienced four separate blooms during the summer months that lasted one to three weeks. Phosphorous concentrations on Utah Lake varied across site and season. Nitrate concentrations on Deer Creek increased over season with a ten-fold increase in concentration. We characterized Cyanobacteria blooms as either bloom communities (growing populations of Cyanobacteria) or as bust communities (declining populations of Cyanobacteria). Using these designations, we modeled the growth and decline of the Cyanobacteria populations across season with top-down and bottom up-controls. Based on generalized least-squared modeling, eukaryotic grazing does not affect relative Cyanobacteria abundances as much as nutrient limitations. Aphanizomenom strain MDT14a was positively correlated with temperature (P < 0.028) and the concentration of K (P = 0.007) and negatively correlated with increases in conductivity (P = 0.0088). Microcystis was positively correlated with increasing levels of SRP (P < 0.001) and negatively correlated with higher Ca concentrations (P = 0.008) and PP (P = 0.008). Busts of Microcystis were related to decreases in nitrate (P = 0.06) and lower total lake depths (P = 0.03). Phormidiaceae sp. relative abundance was negatively correlated with higher levels of TDN (P = 0.01-0.001) and Mg (P = 0.01) and positively correlated with higher S concentrations (P = 0.007). Our findings suggest that micronutrients and more bioavailable forms of P may potentially allow Cyanobacteria to break dormancy and proliferate HAB communities.
10

"Det är inte bara folkvalda politiker som utövar offentlig makt" : En jämförande studie gällande främjande av integration i fem kommuner i Stockholms län / "It is not just elected representatives that exercise public power" : A comparative study of integration in five municipalities in Stockholm County

Degard, Emelie, Abdulla, Maya January 2009 (has links)
<p>Based on different integration policies, we aim to examine how five municipalities in Stockholm County are working to promote integration at a local level with focus on voter participation and to some extent, representativeness among foreign-born. Statistics provided by SCB shows that foreign-born tends to vote to a lesser extent than those born in Sweden. Further, we aim to examine the implementation of two policy documents established at a national level concerning integration in contrast to policy documents established at a local level in each different municipality. Further, we aim to examine summaries of actions taken in response to the local integration programs, as well as personal interviews. Each municipality will be considered separately, but we thus seek to make a comparative study. The study will be based on a qualitative approach. The implementation process of both central and local policy decisions concerning the promotion of integration will also be discussed in terms of two existing theories of implementation, based on two different perspectives. The result shows that interaction between different participants, such as local officials and politicians, is of importance for the implementation process. All of the studied municipalities have taken some actions in order to implement their goals concerning integration.</p>

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