1,150 research outputs found
A supercontinuum source based on an electroabsorption-modulated laser for long distance DWDM transmission
No full textFunctionalised DNA - introducing and applying a versatile porphyrin molecular ruler
No full textPorphyrin moieties were rigidly attached to DNA to generate an accurate molecular ruler. Molecular ruler analysis was conducted using steady-state fluorescence, circular dichroism and small angle X-ray scattering spectroscopic techniques, in an attempt to analyse the FRET, exciton coupling and scattering intensity between different porphyrin-porphyrin labelled DNA combinations. A 21-mer test sequence was labelled with a porphyrin in one position on one strand, and seven different positions on seven complementary strands, to overall give seven porphyrin-porphyrin inter-strand combinations. Steady-state fluorescence and circular dichroism spectroscopic analysis of the Soret band revealed individual Watson-Crick bases pair molecular ruler sensitivity. Small angle X-ray scattering attempts between metallated-porphyrin entities did not reveal sufficient scattering at low concentrations, in contrast, an iodinated analogue of the porphyrin system did displayed scattering correlating to different iodine iodine distances. After calibration of the porphyrin system, the moieties were applied to study protein-DNA interactions between Tus, a 36 KDa DNA binding protein, and Ter, a specific 21-mer DNA sequence. Molecular ruler nalysis of the complex required an extended version of the Ter DNA sequence to which modifications were attached. Established FRET pairs FAM and TAMRA were applied to investigate protein-DNA complexation. Native PAGE analysis revealed Tus binds to the extended DNA via a sliding mechanism. Fluorescence analysis of the established FRET pairs identified changes in fluorescence not correlating to changes in FRET, and instead was attributed to emission quenching upon protein binding. Applying the zinc and free base porphyrin version displayed subtle changes in the Soret band circular dichrosim upon complexation, indicating small DNA helical change upon complexation. A 45-mer DNA sequence was designed to form multiple hairpin-duplex conformations with the addition of an appropriate complementary strand. Attaching FRET pairs to the extremes of the DNA sequence enabled multiple DNA conformations, and hence FRET distances to be obtained from one doubly modified DNA sequence. The combinations were characterised by UV-Vis, fluorescence and circular dichroism spectroscopy. Finally, terpyridine labelled DNA sequences selectively formed DNA nanotubes through orthogonal hydrogen bonding and metal complexation interactions. Short DNA strands were designed to self-assemble into long duplexes through a sticky-end approach. Addition of weakly binding metals such as zinc induced the formation of tubular arrays consisting of DNA bundles 50-200 nm wide and 2-50 nm high. TEM displayed additional long distance ordering of the terpyridine-DNA complexes into fibers
Globalization of Equity Markets and the Cost of Capital
No full textThis paper examines the impact of globalization on the cost of equity capital. We argue that the cost of equity capital decreases because of globalization for two important reasons. First, the expected return that investors require to invest in equity to compensate them for the risk they bear generally falls. Second, the agency costs which make it harder and more expensive for firms to raise funds become less important. The existing empirical evidence is consistent with the theoretical prediction that globalization decreases the cost of capital, but the documented effects are lower than theory leads us to expect. We discuss various reasons for why this is the case.
Financial Globalization, Corporate Governance, and Eastern Europe
No full textFor many countries, the most significant barriers to trade in financial assets have been knocked down. Yet, the financial world is not flat because poor governance prevents firms from being widely held and from taking full advantage of financial globalization. Poor governance has implications for corporate finance as well as for macroeconomics. I show that poor governance in Eastern Europe is accompanied, as expected, by high corporate ownership concentration, low firm valuation, poor financial development, and low foreign participation.
Securities Laws, Disclosure, and National Capital Markets in the Age of Financial Globalization
No full textAs barriers to international investment fall and technology improves, the cost advantages for a firm's securities to trade publicly in the country in which that firm is located and for that country to have a market for publicly traded securities distinct from the capital markets of other countries will progressively disappear. However, securities laws remain an important determinant of whether and where securities are issued, how they are valued, who owns them, and where they trade. The value of public firms depends on these laws, so that identical firms subject to different laws are likely to have different values. We show that mandatory disclosure through securities laws can decrease agency costs between corporate insiders and minority shareholders, but only provided the investors can act on the information disclosed and the laws cannot be weakened ex post too much through lobbying by corporate insiders. With financial globalization, national disclosure laws can have wide-ranging effects on a country's welfare, on firms and on investor portfolios, including the extent to which share holdings reveal a home bias. In equilibrium, if firms can choose the securities laws they are subject to when they go public, some firms will choose stronger securities laws than those of the country in which they are located and some firms will do the opposite. These effects of securities laws can be expected to become smaller if differences in national laws and their enforcement decrease and if the costs of private solutions to manage corporate agency conflicts that are substitutes for securities laws fall.
The Limits of Financial Globalization
No full textDespite the dramatic reduction in explicit barriers to international investment activity over the last 60 years, the impact of financial globalization has been remarkably limited. I argue that country attributes are still critical to financial decision-making because of what I call the twin agency problems. These twin agency problems arise because rulers of sovereign states and corporate insiders pursue their own interests at the expense of outside investors. When these twin agency problems are significant, diffuse ownership is inefficient and corporate insiders must co-invest with other investors, retaining substantial equity. The resulting ownership concentration limits economic growth, financial development, and the ability of a country to take advantage of financial globalization. The twin agency problems help explain why the impact of financial globalization has been limited and why financial globalization can lead to capital flight and financial crises. The impact of financial globalization will remain limited as long as these agency problems are significant.
Why Do Firms Engage in Selective Hedging?
No full textSurveys of corporate risk management document that selective hedging, where managers incorporate their market views into firms’ hedging programs, is widespread in the U.S. and other countries. Stulz (1996) argues that selective hedging could enhance the value of firms that possess an information advantage relative to the market and have the financial strength to withstand the additional risk from market timing. We study the practice of selective hedging in a 10-year sample of North American gold mining firms and find that selective hedging is most prevalent among firms that are least likely to meet these valuemaximizing criteria -- (a) smaller firms, i.e., firms that are least likely to have private information about future gold prices; and (b) firms that are closest to financial distress. The latter finding provides support for the alternative possibility suggested by Stulz that selective hedging may also be driven by asset substitution motives. We detect weak relationships between selective hedging and some corporate governance measures, especially board size, but find no evidence of a link between selective hedging and managerial compensation.Corporate risk management, selective hedging, speculation, financial distress, corporate governance, managerial compensation
Why Do U.S. Firms Hold So Much More Cash Than They Used To?
No full textThe average cash to assets ratio for U.S. industrial firms increases by 129% from 1980 to 2004. Because of this increase in the average cash ratio, American firms at the end of the sample period can pay back their debt obligations with their cash holdings, so that the average firm has no leverage when leverage is measured by net debt. This change in cash ratios and net debt is the result of a secular trend rather than the outcome of the recent buildup in cash holdings of some large firms. It is concentrated among firms that do not pay dividends. The average cash ratio increases over the sample period because the cash flow of American firms has become riskier, these firms hold fewer inventories and accounts receivable, and the typical firm spends more on R&D. The precautionary motive for cash holdings appears to explain the increase in the average cash ratio.
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