• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 2
  • 1
  • 1
  • Tagged with
  • 12
  • 12
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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

Oxygen diffusion within arterioles and venules

Mancuso, Thomas 08 June 2009 (has links)
Oxygen transfer was studied within the arterioles and venules (40 to 100 μm in diameter) of a hamster cheek pouch retractor muscle. Previously obtained transluminal oxygen saturation, red blood cell velocity, and hemoglobin concentration were used for the analysis. Because of branching and transfer to the tissue, the measured oxygen profiles across the vessels were nonuniform. At each axial location, the profiles were converted to radial distributions using a convolution algorithm. The results were modeled using a numerical solution of the convective mass transport equation assuming the blood to be a homogenous mixture. Effective diffusion coefficients were found by matching the axial development of the radial oxygen distribution predicted by the analytical model with the experimental data. The resulting oxygen diffusion coefficients were an order of magnitude higher than have been measured in vitro. This appears to support other evidence relating to the higher than expected oxygen transport in the microcirculation. / Master of Science
2

Influence of small conductance calcium-activated potassium channels (SK,Kca2) on long-term memory: global and local analysis across time- and task- dependent measures

Unknown Date (has links)
Small conductance calcium-activated potassium (SK) channels are found ubiquitously throughout the brain and modulate the encoding of learning and memory. Systemic injection of 1-ethyl-2-benzimidalzolinoe (EBIO), a SK channel activator, impairs the encoding of novel object memory and locomotion but spares fear memory encoding in C57BL/6NHsd mice. The memory impairments discovered were not due to non-cognitive performance confounds such as ataxia, anxiety, attention or analgesia. Further investigation with intra-hippocampal application of EBIO revealed SK channels in dorsal CA1 contribute to the encoding deficits seen systemically, but do not account for the full extent of the impairment. Concentrated activation of dorsal CA1 SK channels do not influence fear memory encoding or locomotor impairments. Taken together, these data indicate SK channels, especially in the dorsal hippocampus, have a modulatory role on novel object memory encoding, but not retrieval; however, pharmacological activation of hippocampal SK channels does not appear to influence fear memory encoding. / by Kyle A. Vick, IV. / Thesis (M.A.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.
3

The effect of small conductance calcium-activated potassium channels on emotional learning and memory

Unknown Date (has links)
Small conductance Ca2+-activated K+ (SK) channels have been shown to alter the encoding of spatial and non-spatial memory in the hippocampus by shaping glutamatergic postsynaptic potentials and modulating NMDA receptor-dependent synaptic plasticity. When activated, dendritic SK channels reduce hippocampal neuronal excitability and LTP. Similar SK channel properties have been demonstrated in lateral amygdala (LA) pyramidal neurons. Additionally, induction of synaptic plasticity and beta-adrenoreceptor activation in LA pyramidal neurons causes PKA-mediated internalization of SK channels from the postsynaptic density. Chronic activation of the amygdala through repetitive stressful stimuli can lead to excitatory synaptic strengthening that may create permanent hyper-excitability in its circuitry. This mechanism may contribute to a number of mood and anxiety disorders. The selective influence of SK channels in the LA on anxiety and fear conditioning are not known. The thesis project outlined herein examined whether SK channel blockade by bee venom peptide, apamin, during a repetitive acute fear conditioning paradigm was sufficient to alter fear memory encoding and the resulting behavioral outcome. Following the final fear memory test session, mice were tested in the open field immediately after the second fear conditioning test session. The findings indicate that intracranial LA microinfusions of apamin did not affect memory encoding or subsequent anxiety. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
4

Modelling and simulation of car following driving behaviour

Appiah, Joseph January 2018 (has links)
Driver behaviour has become an important aspect of transport research and over the years a considerable number of car following models have been developed. However, many of these models do not accurately simulate actual driving behaviour due to a lack of suitable qualitative and quantitative data. Moreover, the inclusion of socioeconomic variables in the existing models to ascertain the effect on car following behaviour is lacking. This research underlines the need to further investigate driving behaviour and car following models and to develop techniques to provide a better understanding of driver-vehicle interactions during car following. It investigates data collection techniques and develop better techniques to enhance and improve the collection of microscopic driver behaviour and traffic flow data. This study developed a novel data collection technique which involved instrumenting a private vehicle with front and rear advanced radar sensors, both forward and rear facing video-audio recorders connected to GPS based time series speed and distance measurement devices, an in-vehicle computer logging vehicle speed and a CAN monitoring interface user program to provide real time monitoring and display of data. This system has been utilised to collect a more enhanced and reliable microscopic driver behaviour data in three consecutive vehicles movements which represents an improvement from previously used systems. Three different versions of the GHR car following model were produced for: car following car, truck following car and car following truck. Further analysis of the GHR model showed that in the case of car following car, car drivers responses to the lead car are more obviously stronger than in the case of truck following a car. A distance-based car following model and distance-based two-leader car following model that predict the safe following distance of following vehicles were developed to provide a better understanding of driver behaviour. An extension of these models to include gender, corridor (road) type and vehicle occupancy showed evidence of statistical significance of these variables on driver behaviour. A bus following model that predicts the “following distance” also has been calibrated to describe the interactions between a bus and a car within urban-rural driving conditions. In addition, data analysis showed that drivers were inconsistent with their driving behaviour and that there was variability in driving behaviour across the drivers observed in keeping a safe or desired following distance. This study provides a platform for a number of future research agendas including data collection techniques for collection of driver behaviour data; evaluation of different ITS technologies; impact assessment of ACC on driver safety and improvement of traffic microscopic simulation tools in order to strengthen their ability to simulate realistic transport problems for efficient and effective transportation systems.
5

Electronic Properties and Structure of Functionalized Graphene

Plachinda, Pavel 01 January 2012 (has links)
The trend over the last 50 years of down-scaling the silicon transistor to achieve faster computations has led to doubling of the number of transistors and computation speed over about every two years. However, this trend cannot be maintained due to the fundamental limitations of silicon as the main material for the semiconducting industry. Therefore, there is an active search for exploration of alternate materials. Among the possible candidates that can may [sic] be able to replace silicon is graphene which has recently gained the most attention. Unique properties of graphene include exceedingly high carrier mobility, tunable band gap, huge optical density of a monolayer, anomalous quantum Hall effect, and many others. To be suitable for microelectronic applications the material should be semiconductive, i.e. have a non-zero band gap. Pristine graphene is a semimetal, but by the virtue of doping the graphene surface with different molecules and radicals a band gap can be opened. Because the electronic properties of all materials are intimately related to their atomic structure, characterization of molecular and electronic structure of functionalizing groups is of high interest. The ab-inito (from the first principles) calculations provide a unique opportunity to study the influence of the dopants and thus allow exploration of the physical phenomena in functionalized graphene structures. This ability paves the road to probe the properties based on the intuitive structural information only. A great advantage of this approach lies in the opportunity for quick screening of various atomic structures. We conducted a series of ab-inito investigations of graphene functionalized with covalently and hapticly bound groups, and demonstrated possible practical usage of functionalized graphene for microelectronic and optical applications. This investigation showed that it is possible [to] produce band gaps in graphene (i.e., produce semiconducting graphene) of about 1 eV, without degrading the carrier mobility. This was archived by considering the influence of those adducts on electronic band structure and conductivity properties.
6

Den (o)hållbara jämställdheten : En genusvetenskaplig studie av hållbarhetsprojekt inom tranpsortsektorn

Norling Karlsson, Jennica January 2021 (has links)
This study examines two EU-funded sustainability projects within the Swedish transport sector. The projects are initiated by the County Administrative Board of Gotland and the County Administrative Board of Västmanland. The purpose of the study is to investigate which “problems” that are represented within the projects, what kind of change these particular interpretations of the problem bring about, and, how this could be understood from a feminist perspective. Through analysis of project documents and interviews, the study investigates how the concept of gender equality is understood and implemented in these projects. The analysis is based on five analytical questions inspired by Carol L. Bacchi’s approach “What´s the Problem Represented to be”. The study answers the following research questions; how is the connection between gender, gender equality and sustainability understood in the projects? What obstacles and opportunities for sustainable gender equality work is expressed through people on leading positions within the projects? And; how can this be interpreted from an ecofeminist perspective? The study shows that sustainability and gender equality are linked within the projects through a focus on gender and accessibility. In summary, there are three dominant problem representations. These problem representations are; Gendered climate impact, gendered transport habits and behaviors, The lack of female professional drivers and Gendered jargons and attitudes within the organizations. The study shows that the problem representations form a basis for measures that emphasize that, for the most part, women as a group are expected to be the ones responsible for the change. The concluding discussion illuminates some of the alternative problems and possible changes that these particular problem representations obscure. The awareness of the effects of these problem representations within the transport sector opens up to broaden the societal and scientific conversations on the matter.
7

Identifying barriers to the implementation of bus policy at a local level in Great Britain using a decision support framework

McTigue, Clare January 2018 (has links)
The current debate on transport policy in the UK is focused on the need for a sustainable transport system. Buses play a vital role in achieving this, as they are the most frequently used and most accessible mode of public transport. However, the literature shows that the delivery of sustainable transport policies is not producing the desired outcomes (Hull, 2009) and the application of such policies in real situations remains inconsistent. This is evident across the UK where there has been a decrease in bus patronage and bus mileage. To address this gap, the aim of this research is to identify why bus policies are not imple-mented successfully at a local level and to provide recommendations for implementation and decision making that will aid policy makers, local authority staff, regional transport partnerships, bus operating companies and other practitioners working within the field of transport. A mixed methodology was chosen for this research and is divided into three key stages to address the research problem. The first methodology included an online ques-tionnaire and 143 questionnaires were sent to all public transport officers in Great Britain. 80 surveys were returned giving a response rate of 56%. The second methodology in-cluded telephone interviews conducted with 10 of those public transport officers who responded to the questionnaire in order to elicit a deeper understanding of the results, which could not be achieved from the questionnaire results alone. Finally, the third meth-odology included four case studies on specific bus schemes within Great Britain. These case studies were the Quality Contract Scheme in Tyne and Wear, Fastlink Scheme in Glasgow, Bus Priority Scheme in Solihull and Smart Ticketing Scheme in Dundee. While the questionnaires and telephone interviews provide an overview of bus policy imple-mentation across Great Britain, the multiple case studies were required to investigate the topic in depth, thus identifying the greatest barriers to bus policy implementation. Analysis of the three sets of data is based on the application of a new decision support frame-work developed in this research. The findings in this thesis reveal that local authorities in Great Britain are under-performing in the implementation of bus policy due to the barriers they face. The greatest barriers to implementation include the lack of a policy document; the characteristics of the organisation; availability of resources; intra-organisation support and communication; economic, social and political environments; and opposition, conflict, and ambiguities. Overall, this research has identified several concerns with bus policy implementation. The most obvious concern is the unclear link between policy objectives and measures and the setting and monitoring of performance targets. Meanwhile, the deregulation of the bus sector in the UK means that, in some cases, a lack of control over the implementation of certain measures places limits on policy implementation and results in the frequent im-plementation of policy measures that are achievable rather than those that are necessary to the achievement of policy objectives. The findings from this research also help policy-makers and transport planners to predict what makes implementation successful and to address problems and issues through improved policies and regulations, as well as to an-ticipate and plan for likely barriers. Moreover, addressing these barriers can help tackle the decline in bus mileage and bus usage across Great Britain.
8

Nanocapsules: Calix[4]arene Derivatives that Self-Assemble through Ionic Interactions in Polar Solvents

Sasine, Joshua Sidney 20 April 2005 (has links)
Molecular capsules consist of two or more molecules that bind through either covalent or noncovalent interactions to form a structure with an internal void capable of containing guest molecules. These capsules can be used in catalysis/biocatalysis, in drug transport and delivery, in supramolecular arrays, and to stabilize reactive intermediates. Cavitands and calix[4]arenes are two types of macrocycles that have been used to form molecular capsules. Cavitands are used to form capsules called carceplexes, hemicarceplexes, and hemicarcerands through covalent bonds when two molecules are bridged together rim to rim. Calix[4]arene derivatives self-assemble reversibly through noncovalent interactions such as hydrogen bonding and ionic bonding to form capsules. Capsules formed form cavitands and calix[4]arenes have been shown to encapsulate a variety of guest molecules in nonpolar solvents. In order for the capsules to be used for biological applications, the capsules need to encapsulate guest molecules in water. There are only a few examples of capsules that encapsulate guests in polar solvents. Calix[4]arenes derivatives substituted with charged substituents on the upper rim and propyl groups on the lower rim were synthesized. These derivatives dimerize through ionic interactions in polar solvents forming both heterodimers and homodimers. These dimers will be used to encapsulate various guest molecules. Although the ionic propoxycalix[4]arene monomers are water-soluble, the heterodimers are not. This is due to the shielding of the charges upon assembly leaving only the propyl groups on the lower rim exposed to the polar solvent. To increase dimer solubility in water, calix[4]arene derivatives are being synthesized with hydroxy ethyl groups instead of the propyl groups on the lower rim. When the charged hydroxyethoxycalix[4]arene derivatives dimerize, the alcohols will be exposed to the polar solvent instead of the propyl groups increasing the water-solubility of the capsules.
9

Impact of ubiquitous real-time information on bus passenger route choice

Islam, Md Faqhrul January 2018 (has links)
Over the last decade, Ubiquitous Real-time Passenger Information (URTPI) has become popular among public transport passengers. The effectiveness of URTPI and hence the value of the investments into the necessary systems can be increased with a clear understanding of how URTPI influences passenger behaviour. However, such an understanding is still limited and fragmented. In particular, very little is known about the impact of URTPI on route choice. This study fills this gap evaluating the impact of URTPI on bus passengers' route choice. A revealed preference survey methodology was adopted for data collection and two questionnaire surveys targeting bus users were carried out. Categorical Regression and discrete choice models, such as Binary Logit Model and Multinomial Logit Model, have been applied to analyse the survey data. The study reveals that trip length, passenger age and profession are the main factors influencing the use of URTPI.Having access toURTPI, the frequency of its use is strongly influenced by the attributes of information and social norms. Bus arrival time and bus stop location are the two most important contents of information. Changing time ofdeparture from the start and the boarding time are the two most popular actions taken by bus passengers after consulting URTPI. Passengers' decisions are influenced by information on bus arrival time, bus route, and walking distance. As a result of the impact of URTPI on passengers' choices, the demand distribution for bus runs could potentially be changed by 33% and for bus lines by 22%. The overall network demand distribution could be affected in 42% of cases as a result of consulting URTPI.This study implicates that while investing in tailoring the sources of URTPI, passengers' preferred attributes and contents of information should be considered. Transport planners and operators should take the potential impact of URTPI into account to make better predictions of the PT demand distribution.
10

Analýza spokojenosti zákazníků a návrhy opatření na zvýšení její úrovně / Customer Satisfaction Analysis and Recommendations for its Improvement

Jangl, Patrik January 2010 (has links)
The thesis concetrates on the customer satisfaction research with provided service. The customer satisfaction is one of the key success factors on the market. The result and the goal of this thesis is output in the form of suggestions and recommendations, which should lead to an increase in the current level of customer satisfaction in future.

Page generated in 0.0645 seconds