SkyDOT (Sky Database for Objects in the Time Domain): A Virtual Observatory for Variability Studies at LANL

The mining of Virtual Observatories (VOs) is becoming a powerful new method for discovery in astronomy. Here we report on the development of SkyDOT (Sky Database for Objects in the Time domain), a new Virtual Observatory, which is dedicated to the study of sky variability. The site will confederate a number of massive variability surveys and enable exploration of the time domain in astronomy. We discuss the architecture of the database and the functionality of the user interface. An important aspect of SkyDOT is that it is continuously updated in near real time so that users can access new observations in a timely manner. The site will also utilize high level machine learning tools that will allow sophisticated mining of the archive. Another key feature is the real time data stream provided by RAPTOR (RAPid Telescopes for Optical Response), a new sky monitoring experiment under construction at Los Alamos National Laboratory (LANL).Comment: to appear in SPIE proceedings vol. 4846, 11 pages, 5 figure

Isolated Eigenvalues of the Ferromagnetic Spin-J XXZ Chain with Kink Boundary Conditions

We investigate the low-lying excited states of the spin J ferromagnetic XXZ chain with Ising anisotropy Delta and kink boundary conditions. Since the third component of the total magnetization, M, is conserved, it is meaningful to study the spectrum for each fixed value of M. We prove that for J>= 3/2 the lowest excited eigenvalues are separated by a gap from the rest of the spectrum, uniformly in the length of the chain. In the thermodynamic limit, this means that there are a positive number of excitations above the ground state and below the essential spectrum

Enantioselective Synthesis of the Cyclopentyl Core of the Axinellamines

Axinellamines A−D (1−4) are novel bis-guanidine alkaloids isolated from the marine sponge Axinella sp. of which Axinellamines B−D (2−4) have been shown to possess bactericidal activity against Helicobacter pylori, a bacterium implicated in pepticular and gastric cancer.1 These natural products are noteworthy for the structural complexity of the polycyclic framework incorporating fused and spirocyclic ring systems. Moreover, embedded within these structures is a stereochemically complex and densely functionalized cyclopentyl core that presents a daunting synthetic challenge. A similarly substituted cyclopentane core can be found in palau'amine 5 which critically differs from that of 1−4 in the relative stereochemical relationships of the pendant functionality.2 Palau'amine 5 has attracted considerable attention due to its potent antibiotic, immunosuppressive, and cytotoxic properties (Chart 1)