Genome-wide high-resolution mapping of UV-induced mitotic recombination events in Saccharomyces cerevisiae.

In the yeast Saccharomyces cerevisiae and most other eukaryotes, mitotic recombination is important for the repair of double-stranded DNA breaks (DSBs). Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH). In this study, LOH events induced by ultraviolet (UV) light are mapped throughout the genome to a resolution of about 1 kb using single-nucleotide polymorphism (SNP) microarrays. UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells. In addition, UV stimulates recombination in G1-synchronized cells about 10-fold more efficiently than in G2-synchronized cells. Importantly, at high doses of UV, most conversion events reflect the repair of two sister chromatids that are broken at approximately the same position whereas at low doses, most conversion events reflect the repair of a single broken chromatid. Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR) events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers

Currency Traders and Exchange Rate Dynamics: A Survey of the U.S. Market

We report findings from a survey of United States foreign exchange traders. Our results indicate that: (i) in recent years electronically-brokered transactions have risen substantially, mostly at the expense of traditional brokers; (ii) the market norm is an important det e rminant of interbank bid-ask spread and the most widely-cited reason for deviating from the conventional bid-ask spread is a thin/hectic market; (iii) half or more of market respondents believe that large players dominate in the dollar-pound and dollar-Swiss franc markets; (iv) technical trading best characterizes about 30% of traders, with this proportion rising from five years ago; (v) news about macroeconomic variables is rapidly incorporated into exchange rates; (vi) the importance of individual macroe c onomic variables shifts over time, although interest rates always appear to be important; (vii) economic fundamentals are perceived to be more important at longer horizons, while short-run deviations from the fundamentals are attributed to excess speculation and institutional customer/hedge fund manipulation; (viii) speculation is generally viewed positively, as enhancing market efficiency and liquidity, even though it exacerbates volatility; (ix) central bank intervention does not appear to have substantial effect, although there is general agreement that it increases volatility, and finally; (x) traders do not view purchasing power parity as a useful concept, even though a significant proportion (40%) believe that it affects exchange rates at horizons of over six months.

Occupation numbers of the harmonically trapped few-boson system

We consider a harmonically trapped dilute $N$-boson system described by a low-energy Hamiltonian with pairwise interactions. We determine the condensate fraction, defined in terms of the largest occupation number, of the weakly-interacting $N$-boson system ($N \ge 2$) by employing a perturbative treatment within the framework of second quantization. The one-body density matrix and the corresponding occupation numbers are compared with those obtained by solving the two-body problem with zero-range interactions exactly. Our expressions are also compared with high precision {\em{ab initio}} calculations for Bose gases with $N=2-4$ that interact through finite-range two-body model potentials. Non-universal corrections are identified to enter at subleading order, confirming that different low-energy Hamiltonians, constructed to yield the same energy, may yield different occupation numbers. Lastly, we consider the strongly-interacting three-boson system under spherically symmetric harmonic confinement and determine its occupation numbers as a function of the three-body "Efimov parameter".Comment: 16 pages, 7 figure

Generating EPR beams in a cavity optomechanical system

We propose a scheme to produce continuous variable entanglement between phase-quadrature amplitudes of two light modes in an optomechanical system. For proper driving power and detuning, the entanglement is insensitive with bath temperature and $Q$ of mechanical oscillator. Under realistic experimental conditions, we find that the entanglement could be very large even at room temperature.Comment: 4.1 pages, 4 figures, comments are welcome; to appear in PRA, published version with corrections of typo

Dynamics of small trapped one-dimensional Fermi gas under oscillating magnetic fields

Deterministic preparation of an ultracold harmonically trapped one-dimensional Fermi gas consisting of a few fermions has been realized by the Heidelberg group. Using Floquet formalism, we study the time dynamics of two- and three-fermion systems in a harmonic trap under an oscillating magnetic field. The oscillating magnetic field produces a time-dependent interaction strength through a Feshbach resonance. We explore the dependence of these dynamics on the frequency of the oscillating magnetic field for non-interacting, weakly interacting, and strongly interacting systems. We identify the regimes where the system can be described by an effective two-state model and an effective three-state model. We find an unbounded coupling to all excited states at the infinitely strong interaction limit and several simple relations that characterize the dynamics. Based on our findings, we propose a technique for driving transition from the ground state to the excited states using an oscillating magnetic field.Comment: 11 pages, 7 figure