Pattern formation of quantum jumps with Rydberg atoms

We study the nonequilibrium dynamics of quantum jumps in a one-dimensional chain of atoms. Each atom is driven on a strong transition to a short-lived state and on a weak transition to a metastable state. We choose the metastable state to be a Rydberg state so that when an atom jumps to the Rydberg state, it inhibits or enhances jumps in the neighboring atoms. This leads to rich spatiotemporal dynamics that are visible in the fluorescence of the strong transition. It also allows one to dissipatively prepare Rydberg crystals

Comparative Aspects of Mating Behavior Patterns in Six Species of Stink Bugs (Heteroptera: Pentatomidae)

Mating sequences were analyzed for six species of stink bugs using video- tapes. The results consisted of qualitative descriptions of the precopulatory activities of the pairs and quantitative analyses of the number and direction of mating sequences, including the latency to and duration of copulatory lock. It was possible to quantitatively characterize each of the six species tested. In addition, certain infrequent behavior patterns, e.g., head butts, were observed for some species and not others. The results extend the previous information on mating activities in stink bugs, particularly for Euschistus. We interpret our findings with regard to reproductive strategies in different species of stink bugs, and consider the use of behavior as a taxonomic tool

Development and application of a unified balancing approach with multiple constraints

The development of a general analytic approach to constrained balancing that is consistent with past influence coefficient methods is described. The approach uses Lagrange multipliers to impose orbit and/or weight constraints; these constraints are combined with the least squares minimization process to provide a set of coupled equations that result in a single solution form for determining correction weights. Proper selection of constraints results in the capability to: (1) balance higher speeds without disturbing previously balanced modes, thru the use of modal trial weight sets; (2) balance off-critical speeds; and (3) balance decoupled modes by use of a single balance plane. If no constraints are imposed, this solution form reduces to the general weighted least squares influence coefficient method. A test facility used to examine the use of the general constrained balancing procedure and application of modal trial weight ratios is also described

Chemical Differences between K and Na in Alkali Cobaltates

K$_x$CoO$_2$ shares many similarities with Na$_x$CoO$_2$, as well as some important differences (no hydration-induced superconductivity has been reported). At $T_{c2}$=20 K, K$_{0.5}$CoO$_2$ becomes an insulator with a tiny optical gap as happens in Na$_{0.5}$CoO$_2$ at 52 K. This similarity, with a known common structure, enables direct comparisons to be made. Using the K-zigzag structure recently reported and the local density approximation, we compare and contrast these cobaltates at x=0.5. Although the electronic structures are quite similar as expected, substantial differences are observed near the Fermi level. These differences are found to be attributable mostly to the chemical, rather than structural difference: although Na is normally considered to be fully ion, K has somewhat more highly ionic character than does Na in these cobaltates.Comment: 5 paper

Determination of electron-nucleus collision geometry with forward neutrons

There are a large number of physics programs one can explore in electron-nucleus collisions at a future electron-ion collider. Collision geometry is very important in these studies, while the measurement for an event-by-event geometric control is rarely discussed in the prior deep inelastic scattering experiments off a nucleus. This paper seeks to provide some detailed studies on the potential of tagging collision geometries through forward neutron multiplicity measurements with a zero degree calorimeter. This type of geometry handle, if achieved, can be extremely beneficial in constraining nuclear effects for the electron-nucleus program at an electron-ion collider

Installation effects of long-duct pylon-mounted nacelles on a twin-jet transport model with swept supercritical wing

The installation interference effects of an underwing-mounted, long duct, turbofan nacelle were evaluated in the Langley 16-Foot Transonic Tunnel with two different pylon shapes installed on a twin engine transport model having a supercritical wing swept 30 deg. Wing, pylon, and nacelle pressures and overall model force data were obtained at Mach numbers from 0.70 to 0.83 and nominal angles of attack from -2 deg to 4 deg at an average unit Reynolds number of 11.9 x 1,000,000 per meter. The results show that adding the long duct nacelles to the supercritical wing, in the near sonic flow field, changed the magnitude and direction of flow velocities over the entire span, significantly reduced cruise lift, and caused large interference drag on the nacelle afterbody

Short-Run Independence of Monetary Policy Under Pegged Exchange Rates and Effects of Money on Exchange Rates and Interest Rates

Economists generally assert that countries sacrifice monetary independence when they peg their exchange rates. At the same time, central bankers frequently assert that pegging an exchange rate does not eliminate the independence of monetary policy. This paper examines the effects of money-supply changes on exchange rates, interest rates, and production in an optimizing two-country model in which some sectors of the economy have predetermined nominal prices in the short run and other sectors have flexible prices. Money-supply shocks have liquidity effects both within and across countries and induce a cross-country real-interest differential. The model predicts that liquidity effects are highly non-linear and are not likely to be captured well empirically by linear models, particularly those involving only a single country. The most striking implication of the model is that countries have a degree of short-run independence of monetary policy even under pegged exchange rates.

Short-run effects on money when some prices are sticky

Money ; Prices

Antiferromagnetic phase transition in a nonequilibrium lattice of Rydberg atoms

We study a driven-dissipative system of atoms in the presence of laser excitation to a Rydberg state and spontaneous emission. The atoms interact via the blockade effect, whereby an atom in the Rydberg state shifts the Rydberg level of neighboring atoms. We use mean-field theory to study how the Rydberg population varies in space. As the laser frequency changes, there is a continuous transition between the uniform and antiferromagnetic phases. The nonequilibrium nature also leads to a novel oscillatory phase and bistability between the uniform and antiferromagnetic phases.Comment: 4 pages + appendi