Birth, survival and death of languages by Monte Carlo simulation

Simulations of physicists for the competition between adult languages since 2003 are reviewed. How many languages are spoken by how many people? How many languages are contained in various language families? How do language similarities decay with geographical distance, and what effects do natural boundaries have? New simulations of bilinguality are given in an appendix.Comment: 24 pages review, draft for Comm.Comput.Phys., plus appendix on bilingualit

Spot evolution in the eclipsing binary CoRoT 105895502

Stellar activity is ubiquitous in late-type stars. The special geometry of eclipsing binary systems is particularly advantageous to study the stellar surfaces and activity. We present a detailed study of the 145 d CoRoT light curve of the short-period eclipsing binary CoRoT 105895502. By means of light-curve modeling with Nightfall, we determine the orbital period, effective temperature, Roche-lobe filling factors, mass ratio, and orbital inclination of CoRoT 105895502 and analyze the temporal behavior of starspots in the system. Our analysis shows one comparably short-lived (about 40 d) starspot, remaining quasi-stationary in the binary frame, and one starspot showing prograde motion at a rate of 2.3 deg per day, whose lifetime exceeds the duration of the observation. In the CoRoT band, starspots account for as much as 0.6 % of the quadrature flux of CoRoT 105895502, however we cannot attribute the spots to individual binary components with certainty. Our findings can be explained by differential rotation, asynchronous stellar rotation, or systematic spot evolution.Comment: Accepted in A&

The emerging field of language dynamics

A simple review by a linguist, citing many articles by physicists: Quantitative methods, agent-based computer simulations, language dynamics, language typology, historical linguistic

Multiple testing for SNP-SNP interactions

Most genetic diseases are complex, i.e. associated to combinations of SNPs rather than individual SNPs. In the last few years, this topic has often been addressed in terms of SNP-SNP interaction patterns given as expressions linked by logical operators. Methods for multiple testing in high-dimensional settings can be applied when many SNPs are considered simultaneously. However, another less well-known multiple testing problem arises within a fixed subset of SNPs when the logic expression is chosen optimally. In this article, we propose a general asymptotic approach for deriving the distribution of the maximally selected chi-square statistic in various situations. We show how this result can be used for testing logic expressions - in particular SNP-SNP interaction patterns - while controlling for multiple comparisons. Simulations show that our method provides multiple testing adjustment when the logic expression is chosen such as to maximize the statistic. Its benefit is demonstrated through an application to a real dataset from a large population-based study considering allergy and asthma in KORA. An implementation of our method is available from the Comprehensive R Archive Network (CRAN) as R package 'SNPmaxsel'

2008 Progress Report on Brain Research

Highlights new research on various disorders, nervous system injuries, neuroethics, neuroimmunology, pain, sense and body function, stem cells and neurogenesis, and thought and memory. Includes essays on arts and cognition and on deep brain stimulation

Modelling linguistic taxonomic dynamics

This paper presents the results of the application of a bit-string model of languages (Schulze and Stauffer 2005) to problems of taxonomic patterns. The questions addressed include the following: (1) Which parameters are minimally ne eded for the development of a taxonomic dynamics leading to the type of distribution of language family sizes currently attested (as measured in the i number of languages per family), which appears to be a power-law? (2) How may such a model be coupled with one of the dynamics of speaker populations leading to the type of language size seen today, which appears to follow a log-normal distribution?Comment: 18 pages including 9 figure

Disorder induced Coulomb gaps in graphene constrictions with different aspect ratios

We present electron transport measurements on lithographically defined and etched graphene nanoconstrictions with different aspect ratios including different lengths (L) and widths (W). A roughly length-independent disorder induced effective energy gap can be observed around the charge neutrality point. This energy gap scales inversely with the width even in regimes where the length of the constriction is smaller than its width (L<W). In very short constrictions, we observe both resonances due to localized states or charged islands and an elevated overall conductance level (0.1-1e2/h), which is strongly length-dependent in the gap region. This makes very short graphene constrictions interesting for highly transparent graphene tunneling barriers.Comment: 4 pages, 4 figure

Zinc Gluconate in the Treatment of Dysgeusia—a Randomized Clinical Trial

In the treatment of dysgeusia, the use of zinc has been frequently tried, with equivocal results. The aim of the present randomized clinical trial, which involved a sufficiently large sample, was therefore to determine the efficacy of zinc treatment. Fifty patients with idiopathic dysgeusia were carefully selected. Zinc gluconate (140 mg/day; n = 26) or placebo (lactose; n = 24) was randomly assigned to the patients. The patients on zinc improved in terms of gustatory function (p < 0.001) and rated the dysgeusia as being less severe (p < 0.05). Similarly, signs of depression in the zinc group were less severe (Beck Depression Inventory, p < 0.05; mood scale, p < 0.05). With the exception of the salivary calcium level, which was higher in the zinc patients (p < 0.05), no other significant group differences were found. In conclusion, zinc appears to improve general gustatory function and, consequently, general mood scores in dysgeusia patients

Surface differential rotation and prominences of the Lupus post T Tauri star RX J1508.6-4423

We present in this paper a spectroscopic monitoring of the Lupus post T Tauri star RX J1508.6-4423 carried out at two closely separated epochs (1998 May 06 and 10) with the UCL Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope. Applying least-squares convolution and maximum entropy image reconstruction techniques to our sets of spectra, we demonstrate that this star features on its surface a large cool polar cap with several appendages extending to lower latitudes, as well as one spot close to the equator. The images reconstructed at both epochs are in good overall agreement, except for a photospheric shear that we interpret in terms of latitudinal differential rotation. Given the spot distribution at the epoch of our observations, differential rotation could only be investigated between latitudes 15° and 60°. We find in particular that the observed differential rotation is compatible with a solar-like law (i.e., with rotation rate decreasing towards high latitudes proportionally to sin 2l, where l denotes the latitude) in this particular latitude range. Assuming that such a law can be extrapolated to all latitudes, we find that the equator of RX J1508.6-4423 does one more rotational cycle than the pole every 50 ±10 d, implying a photospheric shear 2 to 3 times stronger than that of the Sun. We also discover that the Hα emission profile of RX J1508.6-4423 is most of the time double-peaked and strongly modulated with the rotation period of the star. We interpret this rotationally modulated emission as being caused by a dense and complex prominence system, the circumstellar distribution of which is obtained through maximum entropy Doppler tomography. These maps show in particular that prominences form a complete and inhomogeneous ring around the star, precisely at the corotation radius. We use the total Hα and Hβ emission flux to estimate that the mass of the whole prominence system is about 10 20g. From our observation that the whole cloud system surrounding the star is regenerated in less than 4 d, we conclude that the braking time-scale of RX J1508.6-4423 is shorter than 1 Gyr, and that prominence expulsion is thus likely to contribute significantly to the rotational spindown of young low-mass stars

Transport in coupled graphene-nanotube quantum devices

We report on the fabrication and characterization of all-carbon hybrid quantum devices based on graphene and single-walled carbon nanotubes. We discuss both, carbon nanotube quantum dot devices with graphene charge detectors and nanotube quantum dots with graphene leads. The devices are fabricated by chemical vapor deposition growth of carbon nanotubes and subsequent structuring of mechanically exfoliated graphene. We study the detection of individual charging events in the carbon nanotube quantum dot by a nearby graphene nanoribbon and show that they lead to changes of up to 20% of the conductance maxima in the graphene nanoribbon acting as a good performing charge detector. Moreover, we discuss an electrically coupled graphene-nanotube junction, which exhibits a tunneling barrier with tunneling rates in the low GHz regime. This allows to observe Coulomb blockade on a carbon nanotube quantum dot with graphene source and drain leads