7,045 research outputs found
Symmetry properties of Penrose type tilings
The Penrose tiling is directly related to the atomic structure of certain
decagonal quasicrystals and, despite its aperiodicity, is highly symmetric. It
is known that the numbers 1, , , , ..., where
, are scaling factors of the Penrose tiling. We show that
the set of scaling factors is much larger, and for most of them the number of
the corresponding inflation centers is infinite.Comment: Paper submitted to Phil. Mag. (for Proceedings of Quasicrystals: The
Silver Jubilee, Tel Aviv, 14-19 October, 2007
Balance Sheet Effects in Currency Crises: Evidence from Brazil
"Third-generation currency crises models" argue that capital losses from exchange-rate depreciation propagate the crises to the productive sector. To test these models, we use a firm-level dataset that allows us to measure currency mismatches around the 2002 Brazilian currency crisis. We find that, between 2001 and 2003, firms that shortly before the crisis had large currency mismatches decreased their investment rates by 8.1 percentual points, relatively to other public firms. Moreover, we show that the currency depreciation implied large competitive gains for the exporters, and yet the investment of exporters with large currency mismatches fell by 12.5 percentual points, relatively to other exporters. The estimated falls in investment are economically very relevant, thereby corroborating the relevance of third generation models negative balance sheet effects.
Balance Sheet Effects in Currency Crises: Evidence from Brazil
In third generation currency crises models, balance sheet losses from currency depreciations propagate the crises into the real sector of the economy. To test these models, we built a firmlevel database that allowed us to measure currency mismatches around the 2002 Brazilian currency crisis. We found that between 2001 and 2003, firms with large currency mismatches just before the crisis reduced their investment rates 8.1 percentage points more than other publicly held firms. We also showed that the currency depreciation increased exporters revenue, but those with currency mismatches reduced investments 12.5 percentage points more than other exporters. These estimated reductions in investment are economically very significant, underscoring the importance of negative balance sheet effects in currency crises. Jel Codes:F32; F34; G31; G32Investment; Balance sheets; Currency crises; Hedge; Financial constraints.
TLEP, first step in a long-term vision for HEP
The discovery of H(126) has renewed interest in circular e+e- colliders that
can operate as Higgs factories, which benefit from three unique
characteristics: i) high luminosity and reliability, ii) the availability of
several interaction points, iii) superior beam energy accuracy. TLEP is an e+e-
storage ring of 80-km circumference that can operate with very high luminosity
from the Z peak (90 GeV) to the top quark pair threshold (350 GeV). It can
achieve transverse beam polarization at the Z peak and WW threshold, giving it
unparalleled accuracy on the beam energy. A preliminary study indicates that an
80 km tunnel could be constructed around CERN. Such a tunnel would allow a 100
TeV proton-proton collider to be established in the same ring (VHE-LHC),
offering a long term vision.Comment: This is a contribution to the the Snowmass process 2013: Frontier
Capabilitie
Comments on "Wall-plug (AC) power consumption of a very high energy e+/e- storage ring collider" by Marc Ross
The paper arXiv:1308.0735 questions some of the technical assumptions made by
the TLEP Steering Group when estimating in arXiv:1305.6498 the power
requirement for the very high energy e+e- storage ring collider TLEP. We show
that our assumptions are based solidly on CERN experience with LEP and the LHC,
as well accelerators elsewhere, and confirm our earlier baseline estimate of
the TLEP power consumption.Comment: 6 page
Magnetic behavior of Fe x Sn 1 − x amorphous alloys near the critical composition
International audienc
Subtilisin enzymes: A note on time-resolved fluorescence and circular dichroism properties
AbstractThis note briefly corrects previous information about the time-resolved fluorescence properties of preparations of subtilisin Carlsberg and subtilisin BPN′. We confirm the observation of segmental motion of the single tryptophan in subtilisin Carlsberg by analysis of the time-resolved fluorescence anisotropy, and present circular dichroism and spectroscopic data on the two proteins. Near-UV properties clearly differentiate between the two proteins. Far-UV circular dichroism confirms that the two subtilisins have closely similar secondary structure in solution; the multi-component analysis is consistent with the established X-ray conformations, but the quantitative agreement is still somewhat imperfect
Resonant Fibonacci Quantum Well Structures
We propose a resonant one-dimensional quasicrystal, namely, a multiple
quantum well (MQW) structure satisfying the Fibonacci-chain rule with the
golden ratio between the long and short inter-well distances. The resonant
Bragg condition is generalized from the periodic to Fibonacci MQWs. A
dispersion equation for exciton-polaritons is derived in the two-wave
approximation, the effective allowed and forbidden bands are found. The
reflection spectra from the proposed structures are calculated as a function of
the well number and detuning from the Bragg condition.Comment: 5 pages, 3 figures, submitted to Phys. Rev.
Thermodynamically Stable One-Component Metallic Quasicrystals
Classical density-functional theory is employed to study finite-temperature
trends in the relative stabilities of one-component quasicrystals interacting
via effective metallic pair potentials derived from pseudopotential theory.
Comparing the free energies of several periodic crystals and rational
approximant models of quasicrystals over a range of pseudopotential parameters,
thermodynamically stable quasicrystals are predicted for parameters approaching
the limits of mechanical stability of the crystalline structures. The results
support and significantly extend conclusions of previous ground-state
lattice-sum studies.Comment: REVTeX, 13 pages + 2 figures, to appear, Europhys. Let
Structure factors of harmonic and anharmonic Fibonacci chains by molecular dynamics simulations
The dynamics of quasicrystals is characterized by the existence of phason
excitations in addition to the usual phonon modes. In order to investigate
their interplay on an elementary level we resort to various one-dimensional
model systems. The main observables are the static, the incoherent, and the
coherent structure factor, which are extracted from molecular dynamics
simulations. For the validation of the algorithms, results for the harmonic
periodic chain are presented. We then study the Fibonacci chain with harmonic
and anharmonic interaction potentials. In the dynamic Fibonacci chain
neighboring atoms interact by double-well potentials allowing for phason flips.
The difference between the structure factors of the dynamic and the harmonic
Fibonacci chain lies in the temperature dependence of the phonon line width. If
a bias is introduced in the well depth, dispersionless optic phonon bands split
off.Comment: 12 pages, 15 figure
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