• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 770
  • 563
  • 153
  • 99
  • 59
  • 59
  • 41
  • 41
  • 40
  • 34
  • 28
  • 22
  • 13
  • 9
  • 8
  • Tagged with
  • 2179
  • 461
  • 263
  • 202
  • 187
  • 164
  • 155
  • 145
  • 144
  • 134
  • 122
  • 111
  • 108
  • 105
  • 103
  • 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.
141

Lietuvos vertybinių popierių rinka ir jos raida / The securities market of Lithuania and it's development

Montvydaitė, Jurgita 05 January 2007 (has links)
Finansų rinkos skirstomos į pinigų ir vertybinių popierių rinkas. Autorė trumpai apžvelgia vertybinių popierių rinkos bei šiuo metu svarbiausių pasaulio biržų atsiradimą, tačiau didžiausias dėmesys skiriamas Lietuvos vertybinių popierių rinkai, nes šio darbo tikslas yra išanalizuoti Lietuvos vertybinių popierių rinką 1993 – 2005 metais. Darbe išnagrinėtos vertybinių popierių formos bei rūšys, kurias galima sugrupuoti į nuosavybės vertybinius popierius, skolos vertybinius popierius bei išvestines priemones. Taip pat pateikiami svarbiausi akcijų kainas veikiantys veiksniai. Apžvelgiamos Lietuvos vertybinių popierių rinką reguliuojančios institucijos, jų funkcijų kitimą nuo 1993 metų ir pateikiami duomenys apie šių institucijų atliktą darbą. Apžvelgiami ir rinkos dalyviai bei pateikiamas jų skaičiaus kitimas. Darbo paskutiniame skyriuje autorė analizuoja Lietuvos vertybinių popierių rinkos duomenis – apyvartą, kapitalizaciją, apyvartos pasiskirstymą pagal prekybos sąrašus bei pagal sandorių tipus. / Financial markets are divided into money market and securities market. Although authoress writes shortly about history of securities market and history of the most important Stock Exchanges of the world, the aim of this paperwork is to observe the evaluation of the Lithuanian Securities market. The object of the paperwork – the analysis of Securities market of Lithuania in 1993 – 2005. The forms and kinds of securities are analyzed in this paper work. It is possible to group securities into three kinds: proprietary, debt securities and financial derivatives. Authoress also names factors, which influence prices of equities. Authoress analyzes the Institutions of the Securities market of Lithuania, functions and variation of these functions since 1993 and participants of securities market of Lithuania and gives variation of their number. In the last chapter of this paperwork authoress analizes facts of the securities market of Lithuania – turnover, capitalization, distribution of turnover by trade lists and types of trade.
142

The synthesis of the cyclometallated palladium complexes and their applications in olefin oligomerization and in phenylacetylene oligomerization/polymerization.

Mungwe, Nothando Wandile. January 2007 (has links)
<p><font face="TimesNewRomanPSMT"> <p align="left">This thesis reports the synthesis of the imine ligands from Schiff base condensation reaction of aldehyde derivatives and equimolar quantities of aniline derivatives. The imine ligands spectrometry.</p> </font></p>
143

The impact of incorporating a bond index into the proxy for the market portfolio.

Baines, Donald. January 2011 (has links)
The Capital Asset Pricing model (CAPM) is the most widely used equity valuation model in both the United States of America (U.S.) and South Africa, thus its importance in corporate finance cannot be underestimated. The largest criticism of the CAPM lies in the difficulties with estimating its parameters and in particular the return on the market parameter. Roll (1977) believed that it is impossible to estimate the market portfolio let alone find a good proxy for it. The common trend amongst practitioners is to use a broad based stock index such as the S&P 500 or in South Africa‟s case the All Share Index (ALSI) as a proxy for the market portfolio. However these methods are questionable, as the market portfolio theoretically contains all risky assets held in proportion to their market value, and stock indices ignore large asset classes such as bonds. Furthermore, using a broad based stock index in the South African context ignores South African specific problems such as the supposed segregation of the market to the Resource and Financial and Industrial sectors. Therefore the purpose of this study was to determine whether simply using the broad based stock index, the ALSI, as a proxy for the market portfolio would suffice or whether the inclusion of debt instruments and the acknowledgement of the segregation on the JSE would enhance the proxy‟s performances. First a set of theoretical requirements that a proxy must satisfy to be considered a suitable proxy for the market portfolio were derived. Then a review of literature on the matter was undertaken, which showed that studies in both the U.S. and South Africa had had mixed results. Next, the various proxies were formed, and tested using the two-pass regression method. The two-pass regressions that were run with the model comprising solely of the ALSI as a proxy, produced a negative sloping SML. This result suggested an inverse relationship between risk and return, which is contradictory to the theory set out in chapters two and three. Thus robustness tests were performed on the model, but none solved the problem. Next the proposed multifactor models were tested to see if they would enhance the results of the first model. Although the results improved slightly, they too did not solve the problem. Thus, in conclusion it was found that incorporating a bond index into the proxy for the market portfolio did not significantly enhance the use of the CAPM in South Africa. / Thesis (M.Com.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
144

Effect of tooth bleaching on the shear bond strength of a fluoride-releasing sealant

Phan, Xiem 13 September 2011 (has links)
Objective: To evaluate the effect of an in-office plus at-home bleaching protocol on shear bond strength of orthodontic buttons when using a fluoride-releasing sealant. Methods and Materials: One hundred and sixty extracted human molars were randomly divided into bleached (N=80) and unbleached groups (N=80). The bleached group was treated with 45% carbamide peroxide for half an hour, followed with five applications of 20% carbamide peroxide at 24 hour intervals. After two weeks, lingual buttons were bonded on the teeth in both groups using either Transbond XT primer or Pro Seal sealant. The teeth were then stored in artificial saliva and subjected to shear testings at 24 hours and 3 months using a Zwick Universal Test Machine. Results: The ANOVA analysis of the 24-hour results indicated a significant difference between the four subgroups (p<.0011). Further simple t-tests indicated that the differences were significant only between bleached and unbleached subgroups (p<.0011). The 3-month results showed the mean shear bond strengths of the unbleached group using Pro Seal sealant was statistically significantly lower than the others although still greater than clinically minimal suggested bond strengths. Interestingly, 15% of the bleached teeth exhibited enamel fracture at the 3-month testing. Conclusion: At 24 hours, both Pro Seal sealant and Transbond XT primer appear to be a reliable choice on both bleached and unbleached teeth. However, at the 3-month period, Pro Seal sealant yielded significantly lower shear bond strength on unbleached teeth, nevertheless well within the range of values considered to be "clinically acceptable".
145

DESIGNING MOLECULAR RECOGNITION IN THE CONTEXT OF HYDROGEN BONDING AND MOLECULAR DYNAMICS

Willis, Peter G. 01 January 2001 (has links)
The effect of hydrogen bonding on the conformation of organic moleculesunifies two projects in this thesis. In one project, the stability of the intramolecularhydrogen bond in derivatives of 2-guanidinobenzimidazole was studied bydynamic 1H NMR spectrometry. The impact that this intramolecular hydrogenbond had on the bond order of the neutral guanidino group and on the dynamicconformation of these aromatic structures was related to the concept of hydrogenbond-assisted resonance. In another project, an oligomer possessing repetitiveconformation and capable of much inter- and intramolecular hydrogen bondingwas designed and synthesized. The sensitivity of this oligomer to changes inanion concentration, as well as its own propensity to self-aggregate weremeasured.Hydrogen bonds found in many biological oligomers are connected thougha system of conjugated bonds. Guanidinobenzimidazole is a conjugated systemof carbon and nitrogen, connected by an intramolecular hydrogen bond. Severalderivatives of guanidinobenzimidazole were synthesized, and the effect ofseveral simple alkyl for hydrogen substitutions were studied.Guanidinobenzimidazole was used as a model to study what effect theconjugation and the intramolecular hydrogen bond have on each other.The formation of redundant low energy hydrogen bonds is universal inbiological oligomers. In DNA and RNA multiple hydrogen bonds are formed witha typical energy contribution of only 1-2 kcal/mol. Individually, these interactionsdo not give the biological oligomers their conformational stability, but togetherthey are very stable. The urea and amide based oligomers designed in the workand discussed in the thesis should form multiple hydrogen bonds withthemselves and/or with anionic guests. Chiral oligoureas were designed topossess this characteristic of cooperative conformation that so many biologicaloligomers and polymers share.
146

Competitive markets with informational asymmetries and trading restrictions : welfare analysis and applications to finance

Kalmus, Philip Alexander January 1999 (has links)
This thesis consists of three original articles in the field of general equilibrium with incomplete markets and general equilibrium with asymmetric information, and an introduction to the theory, which traces its development and embeds the following chapters in a common framework. In Pareto Improving Trade Restrictions in an Incomplete Markets Economy, we consider a stylised three period one good general equilibrium model with incomplete security markets. We show that the introduction of an indiscriminate marginal constraint on security trades can lead to a Pareto improvement, even though all prices are endogenous and agents are fully rational and have symmetric information. In Signaling Credit Quality Independently of Contract Choice: a Non-Transaction Cost Approach to Swaps in Anonymous Markets, we demonstrate that under two conditions, swaps are non-redundant securities in anonymous financial markets. Firstly, there is asymmetric information over the project payoff which is financed by swaps. And secondly, borrowers are restricted from being investors at the same time. If either of this condition fails, then swaps are redundant assets. Swaps permit a constrained optimal solution to an asymmetric information problem. Finally, Anonymous Corporate Bond Markets with Asymmetric Information, the main article of this thesis, shows that in an anonymous credit market which is characterised by limited liability and asymmetric information between borrowers and lenders, the nominal rate of interest on tradable debt (the coupon rate) sorts borrowers by their riskiness and in this way has an indirect influence on the price and quantity of bonds traded in equilibrium. This is in contrast to symmetric information models, in which the nominal coupon rate has no function. The paper claims that the adverse sorting effect of the nominal interest rate, as in Stiglitz-Weiss (1981), is maintained in a competitive setting, but that, even though changes in the nominal interest rate result in non-monotonic changes in the deliveries of agents, the orderly functioning of markets is not impaired.
147

Utilisation of mangrove bark extracts in cold-setting wood adhesives

Tahir, Paridah Md January 1995 (has links)
Extraction of mangrove bark with 4.0% aqueous sodium sulfite and 0.4% aqueous sodium carbonate at 100° and 2 hours gives 24-26% yields compared with extraction by water at 70° for 2 hours which gives 21%. The hot water extracts are more acidic (pH 3.6) than is the sulfite extract (pH 5.6); both are reasonably reactive toward formaldehyde (Stiasny number 70.6 using water and 85.4 using aqueous sulfite-carbonate). The <sup>13</sup>C NMR spectra of <I>R. mucronata </I>shows this tannin to have phloroglucinolic A-rings with hydroxy groups at C-5 and C-7 and pyrogallolic B-rings with hydroxy groups at C-3', C-4', and C-5'. The interflavanoid linkages are C-4→C-8 and C-4→C-6. The <sup>13</sup>C NMR spectra also indicate the presence of a considerable amount of carbohydrate which is shown to be mainly rhamnose, glucose, arabinose, and uronic acids. Sulfitation of <I>R. mucronata </I>bark reduces the total carbohydrate and the rhamnose extracted but increases the amount of arabinose and uronic acids. The bark storage period has significant effects on the pH and the reactivity of the aqueous tannin solution. Barks stored for <4 weeks produce higher extraction yields than those stored for > 6 weeks and contain significantly larger amount of reactive tannin and have shorter gel times. The reactivity of bark extracts towards formaldehyde can be controlled either by limiting the duration of bark storage to 4 weeks or by maintaining the aqueous tannin solution at pH <10.0. The aqueous tannin solution from <I>R. mucronata </I>exhibited properties such as viscosity, solubility and tackiness which were superior to those from the <I>R. apiculata </I>extract while the mixed <I>R. mucronata-R. apiculata </I>aqueous tannin solution had properties in between these. These barks could be used singly or together as a source of tannin without the bond strength of the resulting glued joints being significantly affected. The "honeymoon" bonding technique improved the bond strengths of joints made using sulfited tannin but is suitable only for tannin solutions containing > 4% aqueous sodium hydroxide. The viscosity of sulfited tannin adhesives is influenced by (a) the amount of aqueous sodium hydroxide added to the aqueous tannin solution, and (b) the lapse time, i.e. the period between the addition of sodium hydroxide to the aqueous tannin solution and the addition of phenol-resorcinol-formaldehyde (PRF) resin, hardener, and paraformaldehyde. The present study shows that with the addition of 5% w/w sodium hydroxide and at a curing temperature of 40° the sulfited tannin extracts from the bark of mangrove trees can replace about 50% w/w of the PRF resin in cold-setting wood adhesives with the production of bond strengths comparable to those produced by 100% PRF resin.
148

House Prices and Mortgage Defaults: Econometric Models and Risk Management Applications

Wei, Xiangjing 08 August 2010 (has links)
This dissertation first investigates the possible house price trend and the relationship with the mortgage market, from the perspective of risk management; then it chooses the angle from bond insurers and figures out possible methods to avoid capital procyclicality. In Chapter I, we apply vector auto regression models (VAR) and simultaneous equations models (SEM) to estimate the dynamic relations among house price returns, mortgage rates and mortgage default rates, using historical data during the time period of 1979 through second quarter 2008. We find that house prices would be better estimated and predicted with the consideration of the mortgage market. In Chapter II, following the methodology of co-integration, we first construct several succinct measures to display the possible intrinsic values of house prices. In the short run, house price return dynamics are investigated by dynamic adjustments following Capozza et al (2002) and error correction models. We examine the possible overshooting problem of house price returns. By analytical derivations and simulations, we demonstrate the effects of the coefficients on overshooting. In Chapter III, we adopt a structural model with time-varying correlations for bond insurers. We consider losses due to bond insurers’ downgrading and losses from both insurance contracts and investment portfolio. On that basis, we propose forward-looking smoothing rules of capital over a full business cycle, instead of only based on a short-term horizon, to avoid the procyclicality. With the smoothed capital, a bond insurer can actually establish some capital buffer in good times to support the potential losses in crisis.
149

Effect of tooth bleaching on the shear bond strength of a fluoride-releasing sealant

Phan, Xiem 13 September 2011 (has links)
Objective: To evaluate the effect of an in-office plus at-home bleaching protocol on shear bond strength of orthodontic buttons when using a fluoride-releasing sealant. Methods and Materials: One hundred and sixty extracted human molars were randomly divided into bleached (N=80) and unbleached groups (N=80). The bleached group was treated with 45% carbamide peroxide for half an hour, followed with five applications of 20% carbamide peroxide at 24 hour intervals. After two weeks, lingual buttons were bonded on the teeth in both groups using either Transbond XT primer or Pro Seal sealant. The teeth were then stored in artificial saliva and subjected to shear testings at 24 hours and 3 months using a Zwick Universal Test Machine. Results: The ANOVA analysis of the 24-hour results indicated a significant difference between the four subgroups (p<.0011). Further simple t-tests indicated that the differences were significant only between bleached and unbleached subgroups (p<.0011). The 3-month results showed the mean shear bond strengths of the unbleached group using Pro Seal sealant was statistically significantly lower than the others although still greater than clinically minimal suggested bond strengths. Interestingly, 15% of the bleached teeth exhibited enamel fracture at the 3-month testing. Conclusion: At 24 hours, both Pro Seal sealant and Transbond XT primer appear to be a reliable choice on both bleached and unbleached teeth. However, at the 3-month period, Pro Seal sealant yielded significantly lower shear bond strength on unbleached teeth, nevertheless well within the range of values considered to be "clinically acceptable".
150

Evaluation of Moisture Susceptibility of Warm Mix Asphalt

Garcia Cucalon, Maria Lorena 03 October 2013 (has links)
Economic, environmental and engineering benefits promote the rapid implementation of WMA technologies. However, concerns remain based on changes in the production process that may lead to moisture susceptibility in the early life as compared to HMA. To evaluate WMA moisture susceptibility during this critical period, standard laboratory tests were used for three field projects each with an HMA control mixtures and multiple WMA mixtures. Different specimen types were also evaluated to capture differences in mix design, quality control/quality assurance, and field performance. Specimens were evaluated for moisture susceptibility by Indirect Tensile (IDT) Strength, Resilient Modulus (MR) and Hamburg Wheel-Track Testing (HWTT). Specimens for IDT and MR were tested dry and then tested wet after conditioning as described in AASHTO T283 with one freeze-thaw cycle. HWTT was used to assess both moisture susceptibility and rutting potential under repeated loads in the presence of water at elevated temperatures (i.e., 122°F [50°C]), and the output parameters used for evaluation were the calculated Stripping Inflection Point (SIP) and the rut depth at 5000 load cycles. Based on the results of the laboratory tests performed on PMFC cores acquired at construction and with time, WMA during its early life exhibited inferior moisture resistance when compared to HMA. However, with time, specifically after one summer, the dry and wet properties of WMA became equivalent to those of HMA. For WMA constructed in the fall, the results from this study suggest that the inclusion of recycled asphalt pavement (RAP) or an anti-stripping agent may alleviate possible moisture susceptibility issues in the early life during wet, winter weather conditions. While some laboratory test results demonstrated that WMA is more moisture susceptible than HMA, field performance reported to date from the three projects used in this study shows no evidence of moisture damage. Therefore the search for a laboratory test to screen mixtures for moisture susceptibility continues. An alternative approach, applying Griffith crack growth theory and utilizing IDT, MR and air voids% the adhesive bond energy of asphalt mixtures was calculated for Texas field project. This value holds promise for characterizing performance of asphalt mixtures by considering basic properties and grouping into one representative value.

Page generated in 0.0442 seconds