1,650 research outputs found
Coherent control of quantum transport: modulation-enhanced phase detection and band spectroscopy
Amplitude modulation of a tilted optical lattice can be used to steer the
quantum transport of matter wave packets in a very flexible way. This allows
the experimental study of the phase sensitivity in a multimode interferometer
based on delocalization-enhanced Bloch oscillations and to probe the band
structure modified by a constant force.Comment: 8 pages, 3 figures, Submitted to EPJ Special Topics for the special
issue on "Novel Quantum Phases and Mesoscopic Physics in Quantum Gases
STOCK MARKET DEVELOPMENT AND ECONOMIC GROWTH: THE CAUSAL LINKAGE
This paper addresses the question: does stock market development cause growth? It examines the causal linkage between stock market development, financial development and economic growth. The argument is that any inference that financial liberalisation causes savings or investment or growth, or that financial intermediation causes growth, drawn from bivariate causality tests may be invalid, as invalid causality inferences can result from omitting an important variable. The empirical part of this study exploits techniques recently developed by Toda and Yamamoto (1995) to test for causality in VARs, and emphasises the possibility of omitted variable bias. The evidence obtained from a sample of seven countries suggests that a well-developed stock market can foster economic growth in the long run. It also provides support to theories according to which well-functioning stock markets can promote economic development by fuelling the engine of growth through faster capital accumulation, and by tuning it through better resource allocation.Financial Development, Economic Growth, Stock Market, Causality Testing, VARs, Incomplete Systems
Multiple cyclical fractional structures in financial time series
This paper analyses multiple cyclical structures in financial time series. In particular, we focus on the monthly structure of the Nasdaq, the Dow Jones and the Standard&Poor stock market indices. The three series are modelled as long-memory processes with poles in the spectrum at multiple frequencies, including the long-run or zero frequency
Noncommutative Einstein Equations
We study a noncommutative deformation of general relativity where the
gravitational field is described by a matrix-valued symmetric two-tensor field.
The equations of motion are derived in the framework of this new theory by
varying a diffeomorphisms and gauge invariant action constructed by using a
matrix-valued scalar curvature. Interestingly the genuine noncommutative part
of the dynamical equations is described only in terms of a particular tensor
density that vanishes identically in the commutative limit. A noncommutative
generalization of the energy-momentum tensor for the matter field is studied as
well.Comment: 17 Pages, LaTeX, reference adde
Metabolic profile of long-distance migratory flight and stopover in a shorebird
Migrating birds often complete long non-stop flights during which body energy stores exclusively support energetic demands. The metabolic correlates of such long-distance travel in free-living migrants are as yet poorly studied. Bar-tailed godwits, Limosa lapponica taymyrensis, undertake a 4500 km flight to their single spring stopover site and thus provide an excellent model in which to determine the energy fuels associated with endurance travel. To this end, we evaluated plasma concentrations of six key metabolites in arriving godwits caught immediately upon landing near their stopover site. Initial metabolite levels were compared with levels after 5 h of inactive rest to determine how flight per se affects energy metabolism. Birds refuelling on the stopover site were also examined. Arriving godwits displayed elevated plasma free fatty acids, glycerol and butyrate, confirming the importance of lipid fuel in the support of extended migratory activity. Furthermore, elevated plasma triglycerides in these birds suggest that fatty acid provisioning is facilitated through hepatic synthesis and release of neutral lipids, as previously hypothesized for small migrants with high mass-specific metabolic rates. Finally, elevations in plasma uric acid suggest that protein breakdown contributes to the support of long-distance movement, to possibly maintain citric acid cycle intermediates, gluconeogenesis and/or water balance
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