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, $-\tau$, $(-\tau)^2$, $(-\tau)^3$, ..., where $\tau =(1+\sqrt{5})/2$, 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

Alcaloides de l\u27 Iboga

L\u27iboga est un arbuste de l\u27Afrique Equatoriale et du Gabon en particulier, ses racines sont utilisees par les indigenes pour resister a la fatique, a la faim et au sommeil lors de longs parcours a pied ou en pirogue. Ces racines entrent aussi dans les breuvages administres a des individus hebetes pour les tirer rapidernent de leur torpeur au cours de certaines .pratiques de sorcellerie

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.

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