• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 110
  • 10
  • 10
  • 9
  • 7
  • 6
  • 4
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 213
  • 30
  • 24
  • 19
  • 18
  • 15
  • 15
  • 14
  • 14
  • 13
  • 13
  • 12
  • 12
  • 12
  • 12
  • 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.
31

"Bara ett liv till" : En kvalitativ studie om vänskap genom gaming.

Mörkdal, Dennis January 2015 (has links)
Syftet med denna uppsats är att undersöka upplevelser av hur sociala nätverk byggs och upprätthålls genom deltagande i flerspelar digitala spel över internet, så kallade online gaming. Detta har gjorts genom att studera spelare inom genren MMO. Studien har använt sig av Bourdieus kapital teori för att studera om det sker någon utväxling av socialt kapital från online till offline. Den har även sig av Consalvos begrepp gaming kapital för att studera om kunskap i spel kan övergå till ett socialt kapital. Empirin har samlats in genom kvalitativa semistrukturerade intervjuer med fem informanter.Resultatet visar att socialt kapital sällan utväxlas från online till offline. Informanterna har skapat breda kontaktnät online men det är endast vid ett tillfälle i studien då det lett till ett möte offline. Resultatet visar även att gaming kapital kan övergå till socialt kapital. Då det anses som någonting önskvärt inom spelen blir det en resurs som andra spelare efterfrågar och kontakt uppsöks.Slutsatsen är att vänskap bildas genom online spel men är oftast av svagare band och saknar djupare emotionella utbyten. Uppsatsen bidrar med en ökad förståelse av skapande och upprätthållande av vänskap och gemenskap genom online spel och en ökad förståelse i bryggan mellan online och offline.
32

Bridging of SCSI to SATA and Implementationof a SATA Controller using Virtex-5 / Bryggning mellan SCSI och SATA samt implementering av en styrenhet för SATA på en Virtex-5

Landström, Erik January 2009 (has links)
Companies and authorities of today often handle large amount of data, not unusually with a restricted content which should be kept secret from outsiders. One way of accomplish this is to encrypt stored data in real time. For this a hardware solution is ideal since it can be independent, fast enough, and easily added to already existing systems. This report is a starting point to achieve this with two of the most common mass storage standards SATA and SCSI in focus. It is based on the task to develop a FPGA based SATA controller and investigate the possibility to ”speak” SCSI with SATA devices. The working process has involved theoretical studies, system design, test driven development using simulations and hardware tests and technical investigation. The thesis resulted in a SCSI-to-SATA translation investigation pointing out difficulties and presenting a translation model. A SATA host was also implemented in VHDL on a Virtex-5 FPGA that can execute a number of SATA commands on different devices. Simulations performed shows that the total latency reaches one μs/32 bits in the SATA host and that should not be much of a problem for most applications in a possible bridge solution.
33

Adsorption kinetics of cationic polyacrylamides on cellulose fibres and its influence on fibre flocculation

Solberg, Daniel January 2003 (has links)
The adsorption of cationic polyacrylamide (C-PAM) and silicananoparticles onto a model surface of silicon oxide wascompared with the adsorption of C-PAM to fibres and theirinfluence on flocculation of a fibre suspension. An increase inionic strength affects the polyelectrolyte adsorption indifferent ways for these two systems. With the silica surface,an increase in the ionic strength leads to a continuousincrease in the adsorption. However, on a cellulose fibre, theadsorption increases at low ionic strength (1 to 10 mM NaCl)and then decreases at higher ionic strength (10 to 100 mMNaCl). It was shown that the adsorption of nanoparticles ontopolyelectrolyte-covered surfaces has a great effect on both theadsorbed amount and the thickness of the adsorbed layer. Theresults showed that electrostatic interactions were thedominating force for the interaction between both the fibresand the polyelectrolytes, and between the polyelectrolytes andthe silica particles. Furthermore, at higher NaClconcentrations, a significant non-ionic interaction between thesilicon oxide surface/particles and the C-PAM was observed. The adsorption rate of C-PAM onto fibres was rapid andquantitative adsorption was detected in the time range between1 and 8 s at polyelectrolyte addition levels below 0.4 mg/g.Conversely, an increase in the amount of added polymer leads toan increased polymer adsorption up to a quasi-static saturationlevel. However, after a few seconds this quasi-staticsaturation level was significantly lower than the level reachedat electrostatic“equilibrium”. The adsorbed amountof charges at full surface coverage after 1 to 8 s contact timecorresponded to only 2 % of the total fibre charge, whereasafter 30 minutes it corresponded to 15 % of the total fibrecharge. This shows that a full surface coverage at shortcontact times is not controlled by surface charge. Based onthese results, it is suggested that a combination of anon-equilibrium charge barrier against adsorption and ageometric restriction can explain the difference between theadsorption during 1 to 8 s and the adsorption after 30 minutes.With increasing time, the cationic groups are neutralised bythe charges on the fibre as the polyelectrolyte reconforms to aflat conformation on the surface. The addition of a high concentration of C-PAM to a fibresuspension resulted in dispersion rather than flocculation.This behaviour is most likely due to an electrostericstabilisation of the fibres when the polyelectrolyte isadsorbed. Flocculation of the fibre suspension occurred at lowadditions of C-PAM. A maximum in flocculation was found ataround 50 % surface coverage and dispersion occurred above 100% surface coverage. It was also shown that for a given level ofadsorbed polymer, a difference in adsorption time between 1 and2 seconds influenced the flocculation behaviour. An optimum inflocculation at 50 % surface coverage in combination with theimportance of polymer reconformation time at these shortcontact times showed that the C-PAM induced fibre flocculationagrees with La Mer and Healy’s description of bridgingflocculation. A greater degree of flocculation was observed with theaddition of silica nanoparticles to the fibre suspension thanin the single polyelectrolyte system. Flocculation increased asa function of the concentration of added nanoparticles until0.5 mg/g. At higher additions the flocculation decreased againand this behaviour is in agreement with an extended model formicroparticle-induced flocculation. An increase in flocculationwas especially pronounced for the more extended silica-2particles. This effect is attributed to the more extendedpolyelectrolyte layer, since the adsorbed amount wasessentially the same for both silica particles. Finally it was found that fines from the wood fibres had asignificant effect on the flocculation. When fines were added,a greater degree of flocculation was detected. Furthermore, itwas also more difficult to redisperse the fibres with polymerin the presence of fines. <b>Keywords:</b>Adsorption, bridging, cationic polymers,cellulose fibres, electrosteric stabilisation flocculation,ionic strength, nanoparticle, polyelectrolyte, reconformation,retention aids and silica / NR 20140805
34

Myspace, Facebook, and the Strength of Internet Ties: Online Social Networking and Bridging Social Capital

Adkins, Angela M. 09 June 2009 (has links)
No description available.
35

Language Use in Mathematics Textbooks Written in English and Spanish

Bertoch, Kailie Ann 01 December 2014 (has links) (PDF)
Research has suggested that although mathematics is a universal language, the notation, algorithms, and language in which it is taught varies from country to country. The literature has addressed the challenges associated with understanding the language of mathematics in English. Variable is a topic of mathematics where the literature has documented students' difficulty understanding the language of mathematics. Part of that difficulty is attributed to the fact that mathematics and English each have their own register and at times the differences in these registers conflict. This study examined the introduction and use of variable in the middle school textbooks of three English speaking countries and three Spanish speaking countries. The results of this study are that textbooks rarely make any attempt to use bridging language, and do not explain to students how they are using variable when they use it. The results of this study also show that the language used to talk about variable is similar English (Spanish) speaking countries.
36

The three-dimensional orientation of gaps has species-dependent effects on bridging performance and gap choice of arboreal snakes

Hoefer, K. Marie 08 October 2012 (has links)
No description available.
37

Design of Bridging Layers in Geosynthetic-Reinforced Column-Supported Embankments

Smith, Miriam E. 04 August 2005 (has links)
Column-supported geosynthetic-reinforced embankments have great potential for application in soft ground conditions when there is a need to accelerate construction and/or protect adjacent facilities from the settlement that would otherwise be induced by the new embankment load. The columns in column-supported embankments can be driven piles, vibro-concrete columns, deep-mixing-method columns, stone columns, or any other suitable type of column. A bridging layer consisting of several feet of sand or sand and gravel is also used to help transfer the embankment load to the columns. Geosynthetic reinforcement is often employed in bridging layers to enhance load transfer to the columns and increase the spacing between columns. Several methods have been developed to calculate the load on the geosynthetic reinforcement, but the calculated loads differ by over an order of magnitude in some cases, and there is not agreement on which method is correct. In this research, a new method was developed for calculating the load on the geosynthetic reinforcement. The new method employs one of the existing mechanistically-based approaches, and combines it with consideration of the stiffnesses of the embankment, geosynthetic, column, and subgrade soil. The new method was verified against the results of a large numerical parameter study, for which the numerical procedures themselves were verified against closed-form solutions for membranes, pilot-scale experiments, and instrumented field case histories. The results of the numerical analyses and the new calculation procedure indicate that the net vertical load on the portion of the geosynthetic reinforcement between columns increases with increasing clear spacing between columns and increasing geosynthetic stiffness. The net vertical load on the geosynthetic decreases with increasing stiffness and strength of the foundation and embankment soils and with increasing elevation of the geosynthetic above the top of the columns or pile caps. A key finding of the research is that, if the subgrade support is good, geosynthetic reinforcement does not have a significant effect on system performance. The new calculation procedure is implemented in an easy-to-use spreadsheet, and recommendations for designing geosynthetic-reinforced bridging layers are provided. / Ph. D.
38

Tuning the Photophysical and Biological Properties of a Series of Ruthenium-Based Chromophores and Chromophore Coupled Cisplatin Analogs with Substituted Terpyridine Ligands

Jain, Avijita 16 January 2009 (has links)
The goal of this research was to develop an understanding of the impact of component modifications on spectroscopic properties, DNA interaction, and bioactivity of tridentate, terpyridine containing ruthenium-based chromophores and chromophore coupled cisplatin analogs. The coupling of a light absorbing unit to a bioactive site offers the potential for developing supramolecules with multifunctional interactions with DNA and other biomolecules. A series of supramolecular complexes of the form [(TL)RuCl(dpp)](PF₆) and [(TL)RuCl(BL)PtCl₂](PF₆) with the BL (bridging ligand) = 2,3-bis(2-pyridyl)pyrazine (dpp) and varying TL (terminal ligand) (tpy = 2,2'':6'',2''-terpyridine, MePhtpy = 4''-(4-methylphenyl)- 2,2'':6'',2''- terpyridine, or tBu3tpy = 4,4'',4''-tri-tert-butyl-2,2'':6'',2''-terpyridine) have been designed and developed. The investigations described in this thesis were focused on the design and development of multifunctional supramolecules with improved DNA interaction and antibacterial properties. The impact of component modifications on photophysical and biological properties of the designed the supramolecular complexes was investigated. A series of supramolecular complexes of the type, [(TL)RuCl(dpp)](PF₆) and [(TL)RuCl(dpp)PtCl₂](PF₆), have been synthesized using a building block approach. Electronic absorption spectroscopy of these types of complexes displayed intense ligand-based transitions in the UV region and metal to ligand charge transfer (MLCT) transitions in the visible region. The Ru to dpp MLCT transitions in RuIIPtII bimetallic complexes were found to be red-shifted relative to the monometallic synthons. The MLCT transitions for [(TL)RuCl(dpp)](PF₆) and [(TL)RuCl(dpp)PtCl₂](PF₆) were centered at ca. 520 and 545 nm, in CH₃CN respectively. The RuIIPtII bimetallic complexes with (TL = tpy, MePhtpy, and tBu3tpy) displayed reversible RuII/III couples at 1.10, 1.10, and 1.01 V vs. Ag/AgCl, respectively. The tpy0/- reductions occurred for TL = tpy, MePhtpy, and tBu3tpy at -1.43, -1.44, and -1.59 V vs. Ag/AgCl, respectively. The RuIIPtII complexes displayed a more positive potential for the dpp0/- couples (-0.50 -0.55, -0.59 V for tpy, MePhtpy, and tBu3tpy, repectively) relative to their monometallic synthons (-1.15, -1.16, and -1.22 V), consistent with the coordination of electron deficient Pt(II) metal center. This research also presents first extensive DNA photocleavage studies of these relatively unexplored tridentate, tpy-containing chromophores. The DNA binding and photocleavage properties of a series of homoleptic and heteroleptic chromophores and RuIIPtII bimetallic complexes were investigated using agarose gel electrophoresis and equilibrium dialysis experiments. The heteroleptic complexes, [(MePhtpy)RuCl(dpp)](PF₆), [(tpy)RuCl(dpp)](PF6), and [(tBu3tpy)RuCl(dpp)](PF6), were found to photocleave DNA more efficiently than homoleptic complexes, [Ru(MePhtpy)2]2+, [Ru(tpy)2]2+, and [Ru(tBu₃tpy)2]2+, in the presence of oxygen. Coupling of [(TL)RuCl(BL)] subunit to a cis-PtIICl2 site provides for the application of typically shorter lived RuII(tpy) based chromophores in DNA photocleavage. The [(TL)RuCl(dpp)PtCl₂]+, complexes displayed covalent binding to DNA and photocleavage upon irradiation with visible light modulated by TL identity. The impact of component modifications on antibacterial properties of the designed molecules was explored for the first time. Both the RuIIPtII bimetallic complexes and their monometallic analogs displayed antibacterial properties. [(MePhtpy)RuCl(dpp)](PF₆) was found to be the most efficient antibacterial agent in the series of monometallic and RuIIPtII bimetallic complexes, displaying cell growth inhibition at 0.05 mM concentration compared to 0.1 mM concentration of [(MePhtpy)RuCl(dpp)PtCl₂](PF₆) needed to display the similar effect. A direct correlation was found to exist between the DNA interaction and bactericidal properties of the designed supramolecules. The effects of light on antibacterial properties of [(MePhtpy)RuCl(dpp)](PF₆) were also briefly examined. This complex represents the first inorganic chromophore-based photodynamic antibacterial agent. / Ph. D.
39

Synthesis of New Molecule-Based Magnets using Bridging Organic Radicals

Houser, Christopher L. 12 July 2019 (has links)
Several new families of organic acceptors that are candidates as building blocks of molecule-based ferrimagnets were synthesized and characterized. These families include fluorodicyanostilbenes, a tetrachlorodicyanostilbene, naphthyltricyanoethylenes, bromophenyltricyanoethylenes, and an anthryltricyanoethylene. The magnetic networks were synthesized by reacting each acceptor with V(CO)6. The magnets synthesized in this study were characterized using a SQUID magnetometer, elemental analysis, and infrared spectroscopy. Although some combinations failed to yield magnetically ordered materials, others exhibited ordering temperatures in the range of 95 K – 260 K. The ordering temperatures and saturation magnetizations were compared among families of acceptors and correlated with individual properties of the acceptors such as reduction potential and structure. / Doctor of Philosophy / Several new families of organic molecules have been created and examined for use as building blocks of molecule-based magnets. These families include fluorodicyanostilbenes, a tetrachlorodicyanostilbene, naphthyltricyanoethylenes, bromophenyltricyanoethylenes, and an anthryltricyanoethylene. The 3-D magnetic scaffoldings were created by combining an individual organic molecule in one of the families listed above with vanadium. The magnets created in this study were examined using a SQUID magnetometer, elemental analysis, and infrared spectroscopy. Some of the combinations of the organic molecules with vanadium failed to result in a 3-D magnetic scaffolding and showed no magnetic properties. Others showed magnetic properties in the below certain temperatures in the range of 95 K – 260 K. The magnetic properties were compared among families of molecules and correlated with individual properties of each molecule such as electronic effects and structure.
40

Ruthenium-Platinum Polypyridyl Complexes: Synthesis and Characterization

Williams, R. Lee 22 August 2001 (has links)
A series of bimetallic (Ru<sup>II</sup>, Pt<sup>II</sup) complexes were synthesized with the general formula [(tpy)RuCl(BL)PtCl₂](PF₆) (tpy = 2,2':6',2"-terpyridine and BL = bridging ligand) and their spectroscopic, electrochemical, and DNA binding properties studied. The bridging ligands used in these complexes were 2,3-bis(2'-pyridyl)pyrazine (dpp), 2,3-bis(2'-pyridyl)quinoxaline (dpq) and 2,3-bis(2'-pyridyl)benzoquinoxaline (dpb). These complexes combine light-absorbing Ru<sup>II</sup>-polypyridyl chromophores and a cis-PtCl₂ structural motif known to bind DNA. The Ru-bound chloride may be substituted, enabling further modification of the spectroscopic properties. The synthesis of [(tpy)RuCl(BL)PtCl₂](PF₆) utilizes a building block approach that allows modifications to the series of complexes within the general synthetic scheme. This illustrates the applicability of this scheme to the development of new series of complexes. The lowest-energy absorption for the three complexes is assigned to a Ru(dπ) → BL(π*) charge transfer transition. This transition shifts to lower energy as the ligand is varied from dpp to dpq to dpb. The first and second reductions are BL<sup>0/-</sup> and BL<sup>-/2-</sup> based and shift to more positive potentials from dpp to dpq to dpb. The Ru<sup>II/III</sup> redox couple remains at a nearly constant potential for the series. All three compounds show DNA binding when incubated with linearized plasmid DNA. Adduct formation was assessed by agarose gel electrophoresis as a retardation of band migration. / Master of Science

Page generated in 0.0978 seconds