217 research outputs found
Screen cues to flatness do affect 3d percepts
No full textWatt SJ, Banks MS, Ernst MO, Zumer JM. Screen cues to flatness do affect 3d percepts. Journal of Vision. 2002;2(7):297
NMR in magnetic molecular rings and clusters
No full textMolecular nanomagnets (MNM) are magnetic molecular clusters containing a limited number of transition ions in a highly symmetric configuration and coupled by strong exchange interaction (either ferromagnetic (FM) or more often antiferromagnetic (AFM)). The magnetic intermolecular interaction is very weak and thus the clusters behave as single nanosize units. NMR has proved to be an excellent probe to investigate the static magnetic properties and the spin dynamics of this new fascinating class of magnetic materials. The chapter contains a comprehensive review of the work performed in the last few years by the present authors with only a brief reference to work performed by other researchers. Most of the NMR measurements were performed on protons but important results were obtained also using other nuclei like 55Mn, 57Fe, 7Li, 23Na, 63Cu, 19F. In some cases the NMR was observed at low temperature in zero external field. Some novel NMR phenomena specific of the systems investigated were discovered and explained. For example in the anisotropic ferrimagnetic clusters Mn12 and Fe8, the ground state is a high total spin S = 10 state whereby the crystal field anisotropy generates an energy barrier typical of superparamagnets. It is shown how NMR and relaxation measurements can detect the microscopic local spin configuration in the ground state and the dynamics of quantum tunnelling of the magnetization (QMT). Another example is the case of the AFM rings, Fe10, Fe6 and Cr8, in which the ground state is a singlet, S = 0, separated from the first triplet excited state by an energy gap of about 5-10 K. By applying a magnetic field one can observe level crossing effects. These e.ects were studied by proton NMR and relaxation measurements vs field at low temperature (1.5-3 K). Finally, the nuclear relaxation rate as a function of temperature in the above mentioned AFM rings displays a field dependent peak at a temperature of the order of the exchange constant J, which can be fitted with a general scaling law. From these data, the lifetime broadening of the energy levels can be determined
Nuclear export is a limiting factor in eukaryotic mRNA metabolism
No full textThe eukaryotic mRNA life cycle includes transcription, nuclear mRNA export and degradation. To quantify all these processes simultaneously, we perform thiol-linked alkylation after metabolic labeling of RNA with 4-thiouridine (4sU), followed by sequencing of RNA (SLAM-seq) in the nuclear and cytosolic compartments of human cancer cells. We develop a model that reliably quantifies mRNA-specific synthesis, nuclear export, and nuclear and cytosolic degradation rates on a genome-wide scale. We find that nuclear degradation of polyadenylated mRNA is negligible and nuclear mRNA export is slow, while cytosolic mRNA degradation is comparatively fast. Consequently, an mRNA molecule generally spends most of its life in the nucleus. We also observe large differences in the nuclear export rates of different 3’UTR transcript isoforms. Furthermore, we identify genes whose expression is abruptly induced upon metabolic labeling. These transcripts are exported substantially faster than average mRNAs, suggesting the existence of alternative export pathways. Our results highlight nuclear mRNA export as a limiting factor in mRNA metabolism and gene regulation.Funder: Cologne Graduate School of Ageing ResearchFunder:
Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/50110000165
Output Smoothing between Regions in Sweden
No full textThe objective of this paper is to analyze the amount of risk sharing of output that takes place between regions in Sweden. Using the approach by Asdrubali et al. (1996), further developed by Mélitz and Zumer (2002), we find that the capital market is the largest source of risk sharing of gross regional product in Sweden. Still, roughly 12 percent of a change in regional output is smoothed among the regions through the fiscal system. Taking a closer look at the fiscal component, the results suggest that national taxes play a larger role in the smoothing process than transfer payments do. There is also some evidence that there are regional differences in the sense that regions located in the south rely more on the capital market as a source of insurance against shocks in output, while the tax and transfer systems provide a larger extent of risk sharing for regions located in the north.risk sharing; taxes; transfers; intergovernmental relations; capital market
Foreign Direct Investment and Productivity Spillovers: Updated Evidence from Central and Eastern Europe
No full textThe paper discusses the inflows of foreign direct investment into the CEE countries and focuses on analysis of productivity spillovers. An overview of the relevance of foreign firms in the CEE economies is presented. Using firm-level data on manufacturing industries for the period 2000–-2005, the total factor productivity of domestic firms is estimated using the Petrin and Levinsohn (2003) method and subsequently related within a panel data model to foreign presence in the same industry and in industries linked via the production chain. The presence of productivity spillovers is tested for across several sub-samples to detect possible conditionalities.Foreign direct investment, productivity, spillovers.
Bonds and Brands : intermediaries and reputation in sovereign debt markets 1820-1830
No full textHow does sovereign debt emerge and become sustainable? This paper provides
a new answer to this unsolved puzzle. Focusing on the early 19th century, we
argue that intermediaries’ market power served to overcome information
asymmetries and sustained the development of sovereign debt. Relying on
insights from corporate finance, we argue that capitalists turned to
intermediaries’ reputations to guide their investment strategies. The outcome
was a two-tier global bond market, which was sustained by hierarchical
relations among intermediaries. This novel theoretical perspective is backed by
new archival evidence and empirical data that have never been gathered so far
The role of the exchange rate for adjustment in boom and bust episodes
No full textNumerous countries have experienced boom-bust episodes in asset prices in the past 20 years. This study looks at stylised facts and conducts statistical and econometric analysis for such episodes, distinguishing between industrialised countries that experienced external adjustment (via real effective exchange rate depreciation during busts) and those that relied on an internal adjustment process (and experienced no depreciation). The study finds that different adjustment experiences are correlated with the degree of macroeconomic imbalances and balance sheet problems. Internal adjustment seems more prevalent when financial vulnerabilities, excess demand and competitiveness loss remain relatively contained in the boom. In the bust, internal adjusters experience more protracted but less deep downturns than external adjusters as imbalances unwind more slowly. Some Central and East European EU Member States are currently experiencing strong credit and asset price growth in conjunction with rapid economic expansion. Against this background the experience of other countries may raise awareness of related policy challenges. JEL Classification: E32, E63, E65Booms and busts, competitiveness, Exchange Rates, external and internal adjustment, financial imbalances
Correlated spin dynamics and phase transitions in pure and disordered 2D S=1/2 antiferromagnets: Insights from NMR-NQR
No full textThis Time is Different: A Panoramic View of Eight Centuries of Financial Crises
No full textThis paper offers a "panoramic" analysis of the history of financial crises dating from England’s fourteenth-century default to the current United States sub-prime financial crisis. Our study is based on a new dataset that spans all regions. It incorporates a number of important credit episodes seldom covered in the literature, including for example, defaults and restructurings in India and China. As the first paper employing this data, our aim is to illustrate some of the broad insights that can be gleaned from such a sweeping historical database. We find that serial default is a nearly universal phenomenon as countries struggle to transform themselves from emerging markets to advanced economies. Major default episodes are typically spaced some years (or decades) apart, creating an illusion that "this time is different" among policymakers and investors. A recent example of the "this time is different" syndrome is the false belief that domestic debt is a novel feature of the modern financial landscape. We also confirm that crises frequently emanate from the financial centers with transmission through interest rate shocks and commodity price collapses. Thus, the recent US sub-prime financial crisis is hardly unique. Our data also documents other crises that often accompany default: including inflation, exchange rate crashes, banking crises, and currency debasements.
International risk sharing in the short run and in the long run
No full textUsing a panel of 23 industrialised countries, the paper investigates how short-run and long-run income risks are shared and how the source of uncertainty matters for the way this risk gets insured. Surprisingly, short-term and long-term output risks are found to be equally well insured. Transitory shocks get smoothed almost completely whereas permanent shocks remain 80 percent uninsured. We find a somewhat more important role for international capital markets than earlier studies. Whereas our results tie in with some recent theoretical insights and are consistent with empirical findings on home bias in international portfolios, they raise the question why permanent shocks are so hard to insure internationally
- …
