On univoque Pisot numbers

We study Pisot numbers $\beta \in (1, 2)$ which are univoque, i.e., such that there exists only one representation of 1 as $1 = \sum_{n \geq 1} s_n\beta^{-n}$, with $s_n \in \{0, 1\}$. We prove in particular that there exists a smallest univoque Pisot number, which has degree 14. Furthermore we give the smallest limit point of the set of univoque Pisot numbers.Comment: Accepted by Mathematics of COmputatio

Amino acids precursors in lunar finds

The consistent pattern is discussed of amino acids found in lunar dust from Apollo missions. The evidence indicates that compounds yielding amino acids were implanted into the surface of the moon by the solar wind, and the kind and amounts of amino acids found on the moon are closely similar to those found in meteorites. It is concluded that there is a common cosmochemical pattern for the moom and meteorites, and this offers evidence of a common course of cosmochemical reactions for carbon

Geologic Mapping of Athabasca Valles

We are approaching the end of the third year of mapping the Athabasca Valles region of Mars. The linework has been adjusted in response to new CTX images and we are on schedule to submit the 4 MTM quads (05202, 05207, 10202, 10207) and ac-companying paper by the end of this fiscal year

Geologic Mapping of Athabasca Valles

Two factors drive us to map the Athabasca Valles area in unusual detail: (1) the extremely well-preserved and exposed surface morphologies and (2) the extensive high resolution imaging. In particular, the near-complete CTX coverage of Athabasca Valles proper and the extensive coverage of its surroundings have been invaluable. The mapping has been done exclusively in ArcGIS, using individual CTX, THEMIS VIS, and MOC frames overlying the THEMIS IR daytime basemap. MOLA shot points and gridded DTMs are also included. It was found that CTX images processed through ISIS are almost always within 300 m of the MOLA derived locations, and usually within tens of meters, with no adjustments to camera pointing. THEMIS VIS images appear to be systematically shifted to the southwest of their correct positions and MOC images are often kilometers off. The good SNR and minimal artifacts make the CTX images vastly more useful than the THEMIS VIS or MOC images. The bulk of the mapping was done at 1:50,000 scale on CTX images. In more complex areas, mapping at 1:24,000 proved necessary. The CTX images were usually simultaneously viewed on a second monitor using the ISIS3 qview program to display the full dynamic range of the CTX data. Where CTX data was not available, mapping was often done at 1:100,000 and most contacts are mapped as approximate

Large-scale variation in density of an aquatic ecosystem indicator species

Funding: This work was supported by the New York State Department of Environmental Conservation and the Hudson River Natural Resource Trustees.Monitoring indicator species is a pragmatic approach to natural resource assessments, especially when the link between the indicator species and ecosystem state is well justified. However, conducting ecosystem assessments over representative spatial scales that are insensitive to local heterogeneity is challenging. We examine the link between polychlorinated biphenyl (PCB) contamination and population density of an aquatic habitat specialist over a large spatial scale using non-invasive genetic spatial capture-recapture. Using American mink (Neovison vison), a predatory mammal and an indicator of aquatic ecosystems, we compared estimates of density in two major river systems, one with extremely high levels of PCB contamination (Hudson River), and a hydrologically independent river with lower PCB levels (Mohawk River). Our work supports the hypothesis that mink densities are substantially (1.64-1.67 times) lower in the contaminated river system. We demonstrate the value of coupling the indicator species concept with well-conceived and spatially representative monitoring protocols. PCBs have demonstrable detrimental effects on aquatic ecosystems, including mink, and these effects are likely to be profound and long-lasting, manifesting as population-level impacts. Through integrating non-invasive data collection, genetic analysis, and spatial capture-recapture methods, we present a monitoring framework for generating robust density estimates across large spatial scales.Publisher PDFPeer reviewe

A classification of (some)Pisot-Cyclotomic numbers

Abstract A complete classification of degree 2, 3 and degree 4 Pisot-Cyclotomic numbers is given. Some examples of higher degrees are also given. Pisot-Cyclotomic numbers have applications to quasicrystals and quasilattices

Cosmic Ray Physics with the LOFAR Radio Telescope

The LOFAR radio telescope is able to measure the radio emission from cosmic ray induced air showers with hundreds of individual antennas. This allows for precision testing of the emission mechanisms for the radio signal as well as determination of the depth of shower maximum $X_{\max}$, the shower observable most sensitive to the mass of the primary cosmic ray, to better than 20 g/cm$^2$. With a densely instrumented circular area of roughly 320 m$^2$, LOFAR is targeting for cosmic ray astrophysics in the energy range $10^{16}$ - $10^{18}$ eV. In this contribution we give an overview of the status, recent results, and future plans of cosmic ray detection with the LOFAR radio telescope.Comment: Proceedings of the 26th Extended European Cosmic Ray Symposium (ECRS), Barnaul/Belokurikha, 201

Optical absorption spectra in fullerenes C60 and C70: Effects of Coulomb interactions, lattice fluctuations, and anisotropy

Effects of Coulomb interactions and lattice fluctuations in the optical absorption spectra of C60 and C70 are theoretically investigated by using a tight binding model with long-range Coulomb interaction and bond disorder. Anisotropy effects in C70 are also considered. Optical spectra are calculated by using the Hartree-Fock approximation followed by the configuration interaction method. The main conclusions are as follows: (1) The broad peaks at excitation energies, 3.7eV, 4.7eV, and 5.7eV, observed in experiments of C60 molecules in a solution are reasonably described by the present theory. Peak positions and relative oscillator strengths are in overall agreement with the experiments. The broadening of peaks by lattice fluctuations is well simulated by the bond disorder model. (2) The optical gap of C70 is larger when the electric field of light is parallel to the long axis of the molecule. The shape of the frequency dispersion also depends on the orientation of the molecule. These properties are common in the free electron model and the model with Coulomb interactions. (3) The spectrum of C70 averaged over bond disorder and random orientations is compared with experiments in a solution. There is an overall agreement about the spectral shape. Differences in the spectra of C60 and C70 are discussed in connection with the symmetry reduction from a soccerball to a rugbyball.Comment: PACS numbers: 78.66.Qn, 78.20.Dj, 71.35.+z, 31.20.Tz; LaTeX, 15 pages, 5 figures (Physical Review B); Note: Please request figures to Authors. They will be sent via snail mai