CPN Tools 4: Multi-formalism and Extensibility

Abstract. CPN Tools is an advanced tool for editing, simulating, and analyzing colored Petri nets. This paper discusses the fourth major re-lease of the tool, which makes it simple to use the tool for ordinary Petri nets, including adding inhibitor and reset arcs, and PNML export. This version also supports declarative modeling using constraints, and adds an extension framework making it easy for third parties to extend CPN Tools using Java.

Non-destructive measurement of the transition probability in a Sr optical lattice clock

We present the experimental demonstration of non-destructive probing of the 1S0-3P0 clock transition probability in an optical lattice clock with 87Sr atoms. It is based on the phase shift induced by the atoms on a weak off-resonant laser beam. The method we propose is a differential measurement of this phase shift on two modulation sidebands with opposite detuning with respect to the 1S0-1P1 transition, allowing a detection limited by the photon shot noise. We have measured an atomic population of 10^4 atoms with a signal to noise ratio of 100 per cycle, while keeping more than 95% of the atoms in the optical lattice with a depth of 0.1 mK. The method proves simple and robust enough to be operated as part of the whole clock setup. This detection scheme enables us to reuse atoms for subsequent clock state interrogations, dramatically reducing the loading time and thereby improving the clock frequency stability.Comment: 4 pages, 5 figure

Role of a Transient Receptor Potential Channels in Marfan Syndrome-induced Aortopathy and Cardiomyopathy

Marfan syndrome (MFS) represents a genetic disorder with variable phenotypic expression. The main cardiovascular sequelae of MFS include aortic aneurysm/dissection and cardiomyopathy. While significant advances in the understanding of TGF-β signaling have led to promising therapeutic targets for the treatment of aortopathy, clinical studies have tempered this optimism. In particular, these studies suggest additional signaling pathways that play a significant role in aortic disease progression. Furthermore, even less is known with respect to effectors involved in MFS-induced cardiomyopathy. To date, studies aimed at elucidating molecular mechanisms involved in MFS-induced disease progression have been hampered by the lack of an accelerated disease model. Meanwhile, transient receptor potential (TRP) channels have been implicated as key effectors in other vascular smooth muscle and cardiomyocyte pathologies, yet there is a paucity of investigation focused on their involvement in the aortopathy and cardiomyopathy of MFS. In these studies, we investigate the importance of TRP channels in the pathogenesis of MFS-induced aortopathy and cardiomyopathy by evaluating differential expression in a novel murine model of accelerated MFS etiolog

Ultrastable lasers based on vibration insensitive cavities

We present two ultra-stable lasers based on two vibration insensitive cavity designs, one with vertical optical axis geometry, the other horizontal. Ultra-stable cavities are constructed with fused silica mirror substrates, shown to decrease the thermal noise limit, in order to improve the frequency stability over previous designs. Vibration sensitivity components measured are equal to or better than 1.5e-11 per m.s^-2 for each spatial direction, which shows significant improvement over previous studies. We have tested the very low dependence on the position of the cavity support points, in order to establish that our designs eliminate the need for fine tuning to achieve extremely low vibration sensitivity. Relative frequency measurements show that at least one of the stabilized lasers has a stability better than 5.6e-16 at 1 second, which is the best result obtained for this length of cavity.Comment: 8 pages 12 figure

Ultraviolet Absorption Spectra at Reduced Temperatures. I. Principles and Methods

Low temperature absorption and fluorescence spectra of solids, liquids, and solutions often reveal increased spectral detail of use in analytical procedures and molecular structure studies. Nevertheless, while qualitative observations of the influence of liquid air temperatures upon optical properties were undertaken very early, investigations of the absorption and fluorescence of organic compounds at the temperature of liquid nitrogen (-195.6°; 77.4 °K.) and below have appeared only sporadically. Because of the potential usefulness of the technique we have undertaken a systematic study of the low temperature spectra of substances of biochemical interest. The present paper discusses the methods employed; subsequent papers will deal with the experimental results. In this work, we have emphasized the wave-length location of absorption bands and the accurate determination of relative optical densities rather than precision in the determination of absolute optical densities, thus permitting the use of simpler methods than would otherwise be necessary

INTEGRAL observations of the Large Magellanic Cloud region

We present the preliminary results of the INTEGRAL survey of the Large Magellanic Cloud. The observations have been carried out in January 2003 (about 10^6 s) and January 2004 (about 4x10^5 s). Here we concentrate on the bright sources LMC X-1, LMC X-2, LMC X-3 located in our satellite galaxy, and on the serendipitous detections of the Galactic Low Mass X-ray Binary EXO 0748-676 and of the Seyfert 2 galaxy IRAS 04575-7537.Comment: 4 pages, 7 figures. To be published in the Proceedings of the 5th INTEGRAL Workshop: "The INTEGRAL Universe", February 16-20, 2004, Munic