Comment on "Material Evidence of a 38 MeV Boson"

In the recent preprint 1202.1739 it was claimed that preliminary data presented by COMPASS at recent conferences confirm the existence of a resonant state of mass 38 MeV decaying to two photons. This claim was made based on structures observed in two-photon mass distributions which however were shown only to demonstrate the purity and mass resolution of the {\pi}0 and {\eta} signals. The additional structures are understood as remnants of secondary interactions inside the COMPASS spectrometer. Therefore, the COMPASS data do not confirm the existence of this state.Comment: 2 pages, 7 figure

Multivariate Copula Models at Work: Outperforming the desert island copula?

Since the pioneering work of Embrechts and co-authors in 1999, copula models enjoy steadily increasing popularity in finance. Whereas copulas are well-studied in the bivariate case, the higher-dimensional case still offers several open issues and it is by far not clear how to construct copulas which sufficiently capture the characteristics of financial returns. For this reason, elliptical copulas (i.e. Gaussian and Student-t copula) still dominate both empirical and practical applications. On the other hand, several attractive construction schemes appeared in the recent literature prom sing flexible but still manageable dependence models. The aim of this work is to empirically investigate whether these models are really capable to outperform its benchmark, i.e. the Student-t copula (which is termed by Paul Embrechts as "desert island copula" on account of its excellent fit to financial returns) and, in addition, to compare the fit of these different copula classes among themselves. --KS-copula,Hierarchical Archimedian,Product copulas,Pair-copula decomposition

Comparative study of hormonal counterregulation during GCIIS-guided hypoglycemia tests using human Proinsulin and Human Insulin (recombinant DNA)

Schlechte Scanvorlage

Storage Capacity of Two-dimensional Neural Networks

We investigate the maximum number of embedded patterns in the two-dimensional Hopfield model. The grand state energies of two specific network states, namely, the energies of the pure-ferromagnetic state and the state of specific one stored pattern are calculated exactly in terms of the correlation function of the ferromagnetic Ising model. We also investigate the energy landscape around them by computer simulations. Taking into account the qualitative features of the phase diagrams obtained by Nishimori, Whyte and Sherrington [Phys. Rev. E {\bf 51}, 3628 (1995)], we conclude that the network cannot retrieve more than three patterns.Comment: 13pages, 7figures, revtex

Scalable Synthesis of Two-dimensional Polymer Crystals and Exfoliation into Nanometer-thin Sheets

Two-dimensional materials have moved into the spotlight of researchers. The isolation of single graphene sheets has shown that restricted dimensionality can lead to interesting properties. Bottom-up synthesis of organic, covalently-bonded structures is, however, still challenging. In this publication we give a synopsis of a recently published monomer that is easily accessible and reversibly provides chiral two-dimensional polymer single crystals, which can be exfoliated into nanometer-thin sheets and show promise for applications in, for example, nonlinear optics and ultrathin membranes

Angular Correlations in Internal Pair Conversion of Aligned Heavy Nuclei

We calculate the spatial correlation of electrons and positrons emitted by internal pair conversion of Coulomb excited nuclei in heavy ion collisions. The alignment or polarization of the nucleus results in an anisotropic emission of the electron-positron pairs which is closely related to the anisotropic emission of $\gamma$-rays. However, the angular correlation in the case of internal pair conversion exhibits diverse patterns. This might be relevant when investigating atomic processes in heavy-ion collisions performed at the Coulomb barrier.Comment: 27 pages + 6 eps figures, uses revtex.sty and epsf.sty, tar-compressed and uuencoded with uufile

Non-ergodic one-magnon magnetization dynamics of the antiferromagnetic delta chain

We investigate the one-magnon dynamics of the antiferromagnetic delta chain as a paradigmatic example of tunable equilibration. Depending on the ratio of nearest and next-nearest exchange interactions the spin system exhibits a flat band in one-magnon space - in this case equilibration happens only partially, whereas it appears to be complete with dispersive bands as generally expected for generic Hamiltonians. We provide analytical as well as numerical insight into the phenomenon.Comment: 7 pages, 10 figure