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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.
821

Metal Nitride Diffusion Barriers for Copper Interconnects

Araujo, Roy A. 14 January 2010 (has links)
Advancements in the semiconductor industry require new materials with improved performance. With the introduction of copper as the interconnect material for integrated circuits, efficient diffusion barriers are required to prevent the diffusion of copper into silicon, which is primarily through grain boundaries. This dissertation reports the processing of high quality stoichiometric thin films of TiN, TaN and HfN, and studies their Cu diffusion barrier properties. Epitaxial metastable cubic TaN (B1-NaCl) thin films were grown on Si(001) using an ultra-thin TiN (B1-NaCl) seed layer which was as thin as 1 nm. The TiN/TaN stacks were deposited by Pulsed Laser Deposition (PLD), with the TiN thickness systematically reduced from 15 to 1 nm. Microstructural studies included X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Preliminary Cu diffusion experiments showed that the TiN seed layer thickness had little or no obvious effect on the overall microstructure and the diffusion barrier properties of the TaN/TiN stacks. Epitaxial and highly textured cubic HfN (B1-NaCl) thin films (~100 nm) were deposited on MgO(001) and Si(001) using PLD. Low resistivities (~40 mu omega-cm) were measured with a four point probe (FPP). Microstructural characterizations included XRD, TEM, and HRTEM. Preliminary Cu diffusion tests demonstrated good diffusion barrier properties, suggesting that HfN is a promising candidate for Cu diffusion barriers. Cubic HfN (B1-NaCl) thin films were grown epitaxially on Si(001) substrates by using a TiN (B1-NaCl) buffer layer as thin as ~10 nm. The HfN/TiN stacks were deposited by PLD with an overall thickness less than 60 nm. Detailed microstructural characterizations included XRD, TEM, and HRTEM. The electrical resistivity measured by FPP was as low as 70 mu omega-cm. Preliminary copper diffusion tests showed good diffusion barrier properties with a diffusion depth of 2~3 nm after vacuum annealing at 500 degrees C for 30 minutes. Additional samples with Cu deposited on top of the cubic HfN/TiN/Si(001) were vacuum annealed at 500 degrees C, 600 degrees C and 650 degrees C for 30 minutes. The diffusivity of copper in the epitaxial stack was investigated using HRTEM. The measured diffusion depths, 2 Dt , were 3, 4 and 5 nm at 500 degrees C, 600 degrees C and 650 degrees C respectively. Finally, the diffusivity of Cu into epitaxial HfN was determined to be D=D0 exp(-Q/kT)cm2s-1 with D0=2.3x10-14cm2s-1 and Q=0.52eV.
822

Vad är det som hindrar sjuksköterskan att diskutera sexualitet med patienten? / What is preventing the nurse to discuss sexuality with the patient?

Karlsson, Cecilia January 2007 (has links)
<p>Tidigare forskning visar att patienten kan ha sexuella problem som kan vara fysiska och/eller psykiska, dessa kan till exempel vara smärta och obehag vid penetration, urinläckage, vaginal lubrikation, utebliven orgasm, och erektionsproblem. Samhällets syn på sexualitet påverkar såväl patientens som sjuksköterskans syn på sexualitet och kan ge svårigheter vid diskussion om sexualitet. För att underlätta för sjuksköterskan vid kommunikation med patienten om sexualitet finns det en modell (PLISSIT-modellen). Trots teoretiska hjälpmedel tycks sjuksköterskan ha svårigheter med att diskutera sexualitet med patienten. Syftet med studien var att undersöka vad det är som hindrar sjuksköterskan att diskutera sexualitet med patienten. Metoden som användes var litteraturstudie. Sex teman framträdde från de vetenskapliga artiklarna i dataanalysen: bristande kommunikation, bristande utbildning, sjuksköterskans känslor, inte sjuksköterskans ansvarsområde, samhällssyn och kulturella faktorer och avdelningsmiljö. Resultatet visar att sjuksköterskan känner sig generad när han/hon ska diskutera sexualitet med patienten och tycker att patienten ska ta initiativ till diskussionen. Även sjuksköterskans egna känslor påverkar diskussionen om sexualitet. Sjuksköterskan behöver utbildning och träning i att diskutera sexualitet med patienten. Sjuksköterskor vill ha en plats där de kan sitta ostört med patienten och diskutera sexualitet.</p> / <p>Studies have shown that patients can have physical and mental sexual problems, which can be pain and discomfort with the penetration, leak of urine, vaginal lubrication, loss of orgasm and problems with the erection. Societies view of sexuality influence both the patients and the nurse’s view of sexuality which gives difficulties in discussing sexuality. To facilitate the communication of sexuality between the nurses and the patients the PLISSIT-model can be used. The aim of this study was to identify what is preventing the nurse to discuss the sexuality with the patient. The method of this study was a literature review. Six themes was located from the articles, deficient communication, deficient education, nurses’ feelings, not the nurses’ responsibility, social outlook and cultural factors and the nursing ward environment. The findings were that the nurse feeling embarrassed when he/she discusses sexual problems with the patient and thinks it is the patient who should ask about the sexual problems. The nurses own feelings affect the discussion about sexuality. The nurses need more education and practice to discuss sexuality with the patients. The nurses wish to have a place where they can discuss sexuality with the patient.</p>
823

Implementing E-learning in Traditional Universities: Drivers and Barriers? : A comparative study of two Chinese universities and one Swedish university

Ma, Jing January 2010 (has links)
<p><strong>Introduction: </strong>Along with the rapid spread of the World Wide Web, internet, and personal computers, e-learning has been increasingly adopted by higher educational institutions (<strong>HEIs</strong>). A serial of studies have been conducted in order to study the implementation of e-learning in HEIs.  This study is a comparative study of two Chinese universities and one Swedish university. It is trying to answer the following research questions:</p><ol><li>What are teachers’ attitudes towards e-learning and purpose for using it?</li><li>What are the driving factors and barriers of e-learning implementation?</li><li>How do national cultures influence the e-learning implementation? </li></ol><p><strong>Purpose:</strong> This study is conducted as an explorative study. It is seeking to find out driving factors and barriers of e-learning implementation in HEIs; Analyse the impact of national culture on e-learning implementation based on the findings and the analysis out of Hofstede´s culture dimension model.</p><p><strong>Method: </strong>The deductive approach will be adopted in this study. Therefore, a hypothesis has been built and tested by both primary and secondary data.  Primary data was collected through questionnaires and the secondary was collected from internet resources, books, published articles and conference papers.</p><p><strong>Conclusion: </strong>There are similarities and differences between universities from the two countries, however, the differences are relatively greater than the similarities. Taken into consideration the significant differences in culture of these two countries, the conclusion can be drawn that national culture is a significant ingredient of factors that can affect e-learning implementations in HEIs.</p>
824

Entry into the Swedish Wholesale Electricity Market and the Electricity Price : A Strategic Behavior Analysis

Bhatia, Martina, Evaldsson, Matilda January 2010 (has links)
<p>The aim of this paper is to analyze the strategic behavior of the leading firms on the Swedish wholesale electricity market. This thesis wishes to address the competition situation on the market and how the firms can manipulate the price in order to maximize the profits.</p><p>The Swedish electricity market was deregulated in 1996 and the predicted outcome was that the competition on the market would increase. However, today’s market is highly vertically integrated with three dominating firms; Vattenfall, E.ON, and Fortum. Moreover, the market has similar characteristics of an oligopoly with high entry barriers, limited room for product differentiation, and limited access of information.</p><p>The Herfindahl-Hirschman Index and the Lerner Index show that the wholesale electricity market is highly concentrated and that market power exists.</p><p>Besides external factors that affect the electricity price, such as emission trading and the amount of water in the reservoirs, the leading firms can with their market power manipulate the price. This can be done by preventing new entrants to enter the market which has led to underinvestment in new capacity with lower production costs.</p>
825

Institutional barriers to entry in the Hong Kong stock market : theory, evidence and policy /

Ancrum, E. M. January 1984 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1987.
826

Closed loop building approach to address sustainability challenge into the future of urban areas

Glukhova, Ekaterina, Cividini, Martina, Erimasita, Silvia January 2015 (has links)
Global urbanization trends and climate changes result in a significant pressure for a future development of urban areas. The construction industry can play a primary role in addressing some of the challenges, but in order to make it happen, the phases of design, construction, use and deconstructio of a building should meet the criteria of sustainability. The closed loop approach can help the construction industry to move in the right direction.  This thesis analysis the closed loop approach to identify its potential contribution in solving the sustainability challenges in urban areas, as well as explores the key aspects helping or hindering the implementation of the approach. The methods used for the research include the framework for strategic sustainable development, case study analysis and interviews with experts in the field. The research exposed several gaps in the use of the approach moving towards sustainability, mainly due to the fact that the unique and shared definition of it is missing and neither actions nor tools are suggested for a successful implementation of the approach. Main barriers are related to the material choice, flexibility of the design, communication and legislation aspects, work with supply chain and interaction with stakeholders. Nonetheless most of them are also seen as potential enablers. Recommendations are provided to help overcoming the existing barriers and valorizing the key enablers, but the clear definition of the approach is necessary to exploit potentialitie of the closed loop approach.
827

CdTe/CdS Thin Film Solar Cells Fabricated on Flexible Substrates

Palekis, Vasilios 01 January 2011 (has links)
Cadmium Telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal bandgap of 1.45 eV and its high optical absorption coefficient. The typical CdTe thin film solar cell is of the superstrate configuration where a window layer (CdS), the absorber (CdTe) and a back contact are deposited onto glass coated with a transparent electrode. Substrate CdTe solar cells where the above listed films are deposited in reverse are not common. In this study substrate CdTe solar cells are fabricated on flexible foils. The properties of the Molybdenum back contact, Zinc Telluride (ZnTe) interlayer and CdTe absorber on the flexible foils were studied and characterized using X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Substrate curvature and film flaking was observed during the fabrication as a result of differences in thermal expansion coefficients between the substrate and the deposited films, and also due to impurity diffusion from the foil into the film stack. In order to overcome this problem diffusion barriers where used to eliminate contamination. Silicon dioxide (SiO2), silicon nitride (Si3N4) and molybdenum nitride (MoxNy) were used as such barriers. Electrical characterization of completed devices was carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V) and Spectral Response (SR) measurements. Roll-over was observed in the first quadrant of J-V curves indicating the existence of a back barrier due to a Schottky back contact. The formation of non-rectifying contact to p-CdTe thin-film is one of the major and critical challenges associated with the fabrication of efficient and stable solar cells. Several materials (ZnTe, Cu, Cu2Te, and Te) were studied as potential candidates for the formation of an effective back contact.
828

A Descriptive Study of the Factors that Prevent Principal Candidates from Advancement to the Principal Position

Witcher, Robyn Regina 01 January 2011 (has links)
This qualitative study examined the perceived barriers to the principalship by prepared principal candidates as a means of understanding why some candidates are unsuccessful in acquiring a principalship. The use of a questionnaire, interviews, and reflection postcards served as the data collection methods concerning their lack of success in achieving a principal position. Portraitures were used to illuminate the journey of these candidates as they completed the necessary requirements, developed the skill vital to becoming a principal, and interviewed for prospective openings. The findings revealed that the barrier to the principalship for these candidates is their own lack of awareness regarding who they are and what they know as it pertains to the principalship and their lack of self reflection and self correction skills. Implications for further study include, a study of principal candidates who have acquired principalship after a significant length of time and their perceptions of what corrections they made that advanced their career; comparison study of the preparation experiences of principal candidates who were successful in getting a principalship in contrast to principal candidates who were unable to advance to the role; and a repeat of this study using male candidates.
829

The Aggregated Influences of Poverty Impacting Dental Care Access and Oral Health among Migrant Farmworkers in Tampa, Florida

Kline, Nolan 01 July 2010 (has links)
Oral health is an important aspect of overall health, but many vulnerable populations such as migrant farmworkers are without access to oral healthcare. Although some non-government organizations such as faith-based organizations have attempted to fill gaps left by government and private sectors, a lack of a dental safety net creates limited access to oral health services for migrant farmworkers. Access to care is further constrained by structural factors including low wages, migration route, and high costs of care. Building off a critical medical anthropology approach in understanding oral healthcare access, I argue that limited oral health access for migrant workers in the Tampa Bay area is the result of economic constraints and not cultural beliefs or educational shortcomings. This research therefore demonstrates the social determinants of oral health, and how social disparities can become embodied in marginalized groups such as migrant farmworkers.
830

Breaking Down the Wall: An Examination of Mental Health Service Utilization in African American and Caucasian Parents

Binitie, Idia O. 13 April 2006 (has links)
This study investigated the influence of parents' gender, race, and psychopathology on barriers and attitudes to mental health utilization for themselves and for their children. It was hypothesized that mothers and Caucasian¹ parents would have more positive attitudes and would perceive fewer barriers to mental health services than fathers and African American² parents. A total of 194 African American and Caucasian parents were recruited from the community to participate in this study. Parents completed measures on barriers and attitudes toward treatment for themselves and their children, utilization of mental health services for themselves and their children, and their own current psychological symptoms. Results indicated that 36.3% and 19.4% of parents and children, respectively, had used mental health services during their lifetime. Parents perceived fewer barriers and had more positive attitudes toward seeking services for their children than for themselves. Race and gender differences were found in parental perceptions of barriers and attitudes toward treatment. Furthermore, barriers, attitudes, and psychopathology predicted parents' plan for future utilization of professionals for mental health services. The clinical implications of this study and directions for future research were discussed.

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