GRB 060218/SN 2006aj: A Gamma-Ray Burst and Prompt Supernova at z=0.0335

We report the imaging and spectroscopic localization of GRB 060218 to a low-metallicity dwarf starburst galaxy at z = 0.03345 +/- 0.00006. In addition to making it the second nearest gamma-ray burst known, optical spectroscopy reveals the earliest detection of weak, supernova-like Si II near 5720 Angstroms (0.1c), starting 1.95 days after the burst trigger. UBVRI photometry obtained between 1 and 26 days post-burst confirms the early rise of supernova light, and suggests a short time delay between the gamma-ray burst and the onset of SN 2006aj if the early appearance of a soft component in the X-ray spectrum is understood as a ``shock breakout''. Together, these results verify the long-hypothesized origin of soft gamma-ray bursts in the deaths of massive stars.Comment: 5 pages, 2 figure

Phonon arithmetic in a trapped ion system

Single-quantum level operations are important tools to manipulate a quantum state. Annihilation or creation of single particles translates a quantum state to another by adding or subtracting a particle, depending on how many are already in the given state. The operations are probabilistic and the success rate has yet been low in their experimental realization. Here we experimentally demonstrate (near) deterministic addition and subtraction of a bosonic particle, in particular a phonon of ionic motion in a harmonic potential. We realize the operations by coupling phonons to an auxiliary two-level system and applying transitionless adiabatic passage. We show handy repetition of the operations on various initial states and demonstrate by the reconstruction of the density matrices that the operations preserve coherences. We observe the transformation of a classical state to a highly non-classical one and a Gaussian state to a non-Gaussian one by applying a sequence of operations deterministically

Braided racks, Hurwitz actions and Nichols algebras with many cubic relations

We classify Nichols algebras of irreducible Yetter-Drinfeld modules over groups such that the underlying rack is braided and the homogeneous component of degree three of the Nichols algebra satisfies a given inequality. This assumption turns out to be equivalent to a factorization assumption on the Hilbert series. Besides the known Nichols algebras we obtain a new example. Our method is based on a combinatorial invariant of the Hurwitz orbits with respect to the action of the braid group on three strands.Comment: v2: 35 pages, 6 tables, 14 figure

On the S-wave piD-scattering length in the relativistic field theory model of the deuteron

The S-wave scattering length of the strong pion-deuteron (pi D) scattering is calculated in the relativistic field theory model of the deuteron suggested in [1,2].The theoretical result agrees well with the experimental data. The important role of the Delta-resonance contribution to the elastic pi D-scattering is confirmed.Comment: 7 pages, no figures, accepted for publication in Z. Phys.

Biomimetic engineered muscle with capacity for vascular integration and functional maturation in vivo.

Tissue-engineered skeletal muscle can serve as a physiological model of natural muscle and a potential therapeutic vehicle for rapid repair of severe muscle loss and injury. Here, we describe a platform for engineering and testing highly functional biomimetic muscle tissues with a resident satellite cell niche and capacity for robust myogenesis and self-regeneration in vitro. Using a mouse dorsal window implantation model and transduction with fluorescent intracellular calcium indicator, GCaMP3, we nondestructively monitored, in real time, vascular integration and the functional state of engineered muscle in vivo. During a 2-wk period, implanted engineered muscle exhibited a steady ingrowth of blood-perfused microvasculature along with an increase in amplitude of calcium transients and force of contraction. We also demonstrated superior structural organization, vascularization, and contractile function of fully differentiated vs. undifferentiated engineered muscle implants. The described in vitro and in vivo models of biomimetic engineered muscle represent enabling technology for novel studies of skeletal muscle function and regeneration

Constraining a possible time variation of the gravitational constant G with terrestrial nuclear laboratory data

Testing the constancy of the gravitational constant G has been a longstanding fundamental question in natural science. As first suggested by Jofr\'{e}, Reisenegger and Fern\'{a}ndez [1], Dirac's hypothesis of a decreasing gravitational constant $G$ with time due to the expansion of the Universe would induce changes in the composition of neutron stars, causing dissipation and internal heating. Eventually, neutron stars reach their quasi-stationary states where cooling due to neutrino and photon emissions balances the internal heating. The correlation of surface temperatures and radii of some old neutron stars may thus carry useful information about the changing rate of G. Using the density dependence of the nuclear symmetry energy constrained by recent terrestrial laboratory data on isospin diffusion in heavy-ion reactions at intermediate energies and the size of neutron skin in $^{208}Pb$ within the gravitochemical heating formalism, we obtain an upper limit of the relative changing rate of $|\dot{G}/G|\le4\times 10^{-12}yr^{-1}$ consistent with the best available estimates in the literature.Comment: 27 pages, 11 figures, and 2 tables. Accepted version to appear in PRC (2007

Ultralow-power local laser control of the dimer density in alkali-metal vapors through photodesorption

Ultralow-power diode-laser radiation is employed to induce photodesorption of cesium from a partially transparent thin-film cesium adsorbate on a solid surface. Using resonant Raman spectroscopy, we demonstrate that this photodesorption process enables an accurate local optical control of the density of dimer molecules in alkali-metal vapors.Comment: 4 pages, 4 figure

Universal critical properties of the Eulerian bond-cubic model

We investigate the Eulerian bond-cubic model on the square lattice by means of Monte Carlo simulations, using an efficient cluster algorithm and a finite-size scaling analysis. The critical points and four critical exponents of the model are determined for several values of $n$. Two of the exponents are fractal dimensions, which are obtained numerically for the first time. Our results are consistent with the Coulomb gas predictions for the critical O($n$) branch for $n < 2$ and the results obtained by previous transfer matrix calculations. For $n=2$, we find that the thermal exponent, the magnetic exponent and the fractal dimension of the largest critical Eulerian bond component are different from those of the critical O(2) loop model. These results confirm that the cubic anisotropy is marginal at $n=2$ but irrelevant for $n<2$