Prospects for a Nuclear Optical Frequency Standard based on Thorium-229

The 7.6-eV-isomer of Thorium-229 offers the opportunity to perform high resolution laser spectroscopy of a nuclear transition. We give a brief review of the investigations of this isomer. The nuclear resonance connecting ground state and isomer may be used as the reference of an optical clock of very high accuracy using trapped and laser-cooled thorium ions, or in a compact solid-state optical frequency standard of high stability.Comment: 5 pages, 1 figure; Proceedings of the 7th Symposium on Frequency Standards and Metrology, 5-11 October 2008; reference added for section

Direct comparison between potential landscape and local density of states in a disordered two-dimensional electron system

The local density of states (LDOS) of the adsorbate induced two-dimensional electron system (2DES) on n-InAs(110) is studied by low-temperature scanning tunneling spectroscopy. The LDOS exhibits irregular structures with fluctuation lengths decreasing with increasing energy. Fourier transformation reveals that the k-values of the unperturbed 2DES dominate the LDOS, but additional lower k-values contribute significantly. To clarify the origin of the additional k-space intensity, we measure the potential landscape of the same 2DES area with the help of the tip induced quantum dot. This allows to calculate the expected LDOS from the single particle Schroedinger equation and to directly compare it with the measured one. Reasonable correspondance between calculated and measured LDOS is found.Comment: 7 pages, 4 figures, submitted to PR

Impact Of Oct Diagnostics In Wilson-Konovalov Disease. Correlation Between Ocular Changes And Severity Of The Disease

Wilson disease is a genetically transmitted disease with severe hepatic, neurological and psychiatric findings. Purpose: The aim of our survey is to show a new method for objective evaluation of the Keiser-Fleisher Ring in the cornea in patients with Wilson-Konovalov disease. Material and method: In our prospective study 7 patients with Wilson disease and decreased levels of ceruloplasmine under 5.2 g/l were enrolled. They were divided into two groups – with initial finding of the disease – 3 patients and with developed clinical picture – 4 patients. Two patients were after successful liver transplantation. The Keiser-Fleisher ring has been evaluated biomicroscopically, with color photography and with anterior segment ОСТ (Rtvue, Optovue, 3D OCT 2000, Topcone). Results: In the first group of patients with initial stage of the disease on biomicroscopy a slight yellow orange ring in the corneal periphery has been spotted in some of the cases. The AS OCT showed a well outlined hyper-reflective band on the level of the Descemet membrane corresponding to the cooper accumulation in the cornea. In the second group of patients with developed disease, this hyper reflective band was larger with more than 60 mc in comparison to the previous group. In patients after liver transplantation disappearance of the ring and cooper accumulation was observed. The ring vanished form the periphery to the center. Conclusion: Wilson disease is always suspected in cases of undiagnosed liver dysfunction. Its confirmation however, is in many cases subjective and connected with the detection of Keiser-Fleisher Ring. The proposed method with anterior segment OCT is noninvasive, repeatable and can objectively show the presence or absence of cooper depositions in the cornea. OCT diagnostics might be useful also in the follow up of these patients after liver transplantation

1/Nc1/N_c Rotational Corrections to gAg_A in the NJL Model and Charge Conjugation

We show that the $1/N_c$ rotational corrections to $g_A$, derived using the semiclassical quantization scheme in the NJL model, possess correct properties under charge conjugation.Comment: 4 pages, revtex, no figures, final version published in Phys.Rev.C52(1995)42

Design and Performance of the CMS Pixel Detector Readout Chip

The readout chip for the CMS pixel detector has to deal with an enormous data rate. On-chip zero suppression is inevitable and hit data must be buffered locally during the latency of the first level trigger. Dead-time must be kept at a minimum. It is dominated by contributions coming from the readout. To keep it low an analog readout scheme has been adopted where pixel addresses are analog coded. We present the architecture of the final CMS pixel detector readout chip with special emphasis on the analog readout chain. Measurements of its performance are discussed.Comment: 8 pages, 11 figures. Contribution to the Proceedings of the Pixel2005 Workshop, Bonn, German

Bounded sets of Lagrange multipliers for vector optimization problems in infinite dimension

AbstractThe aim of this paper is to point out some sufficient constraint qualification conditions ensuring the boundedness of a set of Lagrange multipliers for vectorial optimization problems in infinite dimension. In some (smooth) cases these conditions turn out to be necessary for the existence of multipliers as well

Reactive SINDy: Discovering governing reactions from concentration data

The inner workings of a biological cell or a chemical reaction can be rationalized by the network of reactions, whose structure reveals the most important functional mechanisms. For complex systems, these reaction networks are not known a priori and cannot be efficiently computed with ab initio methods, therefore an important approach goal is to estimate effective reaction networks from observations, such as time series of the main species. Reaction networks estimated with standard machine learning techniques such as least-squares regression may fit the observations, but will typically contain spurious reactions. Here we extend the sparse identification of nonlinear dynamics (SINDy) method to vector-valued ansatz functions, each describing a particular reaction process. The resulting sparse tensor regression method “reactive SINDy” is able to estimate a parsimonious reaction network. We illustrate that a gene regulation network can be correctly estimated from observed time series