Weak Coulomb blockade effect in quantum dots

We develop the general non-equilibrium theory of transport through a quantum dot, including Coulomb Blockade effects via a 1/N expansion, where N is the number of scattering channels. At lowest order we recover the Landauer formula for the current plus a self-consistent equation for the dot potential. We obtain the leading corrections and compare with earlier approaches. Finally, we show that to leading and next leading order in 1/N there is no interaction correction to the weak localization, in contrast to previous theories, but consistent with experiments by Huibers et al. [Phys. Rev. Lett. 81, 1917 (1998)], where N=4.Comment: 4 pages, 2 figures. Published versio

Gaussian excitations model for glass-former dynamics and thermodynamics

We describe a model for the thermodynamics and dynamics of glass-forming liquids in terms of excitations from an ideal glass state to a Gaussian manifold of configurationally excited states. The quantitative fit of this three parameter model to the experimental data on excess entropy and heat capacity shows that ``fragile'' behavior, indicated by a sharply rising excess heat capacity as the glass transition is approached from above, occurs in anticipation of a first-order transition -- usually hidden below the glass transition -- to a ``strong'' liquid state of low excess entropy. The dynamic model relates relaxation to a hierarchical sequence of excitation events each involving the probability of accumulating sufficient kinetic energy on a separate excitable unit. Super-Arrhenius behavior of the relaxation rates, and the known correlation of kinetic with thermodynamic fragility, both follow from the way the rugged landscape induces fluctuations in the partitioning of energy between vibrational and configurational manifolds. A relation is derived in which the configurational heat capacity, rather than the configurational entropy of the Adam Gibbs equation, controls the temperature dependence of the relaxation times, and this gives a comparable account of the experimental observations.Comment: 21 pp., 17 fig

Some Finite Size Effects in Simulations of Glass Dynamics

We present the results of a molecular dynamics computer simulation in which we investigate the dynamics of silica. By considering different system sizes, we show that in simulations of the dynamics of this strong glass former surprisingly large finite size effects are present. In particular we demonstrate that the relaxation times of the incoherent intermediate scattering function and the time dependence of the mean squared displacement are affected by such finite size effects. By compressing the system to high densities, we transform it to a fragile glass former and find that for that system these types of finite size effects are much weaker.Comment: 12 pages of RevTex, 4 postscript figures available from W. Ko

New apparatus for DTA at 2000 bar: thermodynamic studies on Au, Ag, Al and HTSC oxides

A new DTA (Differential Thermal Analysis) device was designed and installed in a Hot Isostatic Pressure (HIP) furnace in order to perform high-pressure thermodynamic investigations up to 2 kbar and 1200C. Thermal analysis can be carried out in inert or oxidising atmosphere up to p(O2) = 400 bar. The calibration of the DTA apparatus under pressure was successfully performed using the melting temperature (Tm) of pure metals (Au, Ag and Al) as standard calibration references. The thermal properties of these metals have been studied under pressure. The values of DV (volume variation between liquid and solid at Tm), ROsm (density of the solid at Tm) and ALPHAm (linear thermal expansion coefficient at Tm) have been extracted. A very good agreement was found with the existing literature and new data were added. This HP-DTA apparatus is very useful for studying the thermodynamics of those systems where one or more volatile elements are present, such as high TC superconducting oxides. DTA measurements have been performed on Bi,Pb(2223) tapes up to 2 kbar under reduced oxygen partial pressure (p(O2) = 0.07 bar). The reaction leading to the formation of the 2223 phase was found to occur at higher temperatures when applying pressure: the reaction DTA peak shifted by 49C at 2 kbar compared to the reaction at 1 bar. This temperature shift is due to the higher stability of the Pb-rich precursor phases under pressure, as the high isostatic pressure prevents Pb from evaporating.Comment: 6 figures, 3 tables, Thermodynamics, Thermal property, Bi-2223, fundamental valu

The Glass Transition Temperature of Water: A Simulation Study

We report a computer simulation study of the glass transition for water. To mimic the difference between standard and hyperquenched glass, we generate glassy configurations with different cooling rates and calculate the $T$ dependence of the specific heat on heating. The absence of crystallization phenomena allows us, for properly annealed samples, to detect in the specific heat the simultaneous presence of a weak pre-peak (``shadow transition''), and an intense glass transition peak at higher temperature. We discuss the implications for the currently debated value of the glass transition temperature of water. We also compare our simulation results with the Tool-Narayanaswamy-Moynihan phenomenological model.Comment: submitted to Phys. Re

How a firm can induce legislators to adopt a bad policy

This paper shows why a majority of legislators may vote for a policy that benefits a firm but harms all legislators. The firm may induce legislators to support the policy by suggesting that it is more likely to invest in a district where voters or their representative support the policy. In equilibrium, no one vote may be decisive, so each legislator who seeks the firm’s investment votes for the policy, though all legislators would be better off if they all voted against the policy. And when votes reveal information about the district, the firm’s implicit promise or threat can be credible. Unlike influence mechanisms based on contributions or bribes, the behavior considered is time consistent and in line with the low campaign contributions by special interests

Chiral two-pion exchange and proton-proton partial-wave analysis

The chiral two-pion exchange component of the long-range pp interaction is studied in an energy-dependent partial-wave analysis. We demonstrate its presence and importance, and determine the chiral parameters c_i (i=1,3,4). The values agree well with those obtained from pion-nucleon amplitudes.Comment: 13 pages, no figure

The features and processes underpinning high-quality data generation in participatory research and engagement activities

1. Participatory approaches are widely used by researchers to gather data and insight about how the environment is perceived, valued and used. The participatory activities may be creating information as part of curiosity-driven blue-skies research or to inform policy/practice decision-making. 2. The quality and usability of data derived from participatory approaches are heavily influenced by how activities are conducted. We share a set of features and processes that underpin the generation of high-quality data, based on our collective experience of developing and undertaking participatory activities with an environmental and conservation focus. 3. We propose four general features: (1) depth and breadth of engagement; (2) robustness of the approach; (3) allowing space for surprises; and (4) usability across contexts. We also provide a practical toolbox of processes, and associated facilitation techniques, which can be employed to maximise participant engagement and generate quality data. 4. The features and processes are a practical guide for project leaders/teams to consider in the context of their work, rather than a set of inflexible rules. They should be relevant regardless of the participatory methods used, or the research, policy or practice setting being addressed

Evaluation of Sample Design and Estimation Methods for Great Lakes Angler Surveys

The waters of the Great Lakes support outstanding recreational fishing opportunities. Total catch and effort estimates obtained from on‐site angler surveys are essential for the management of the recreational fisheries. However, quality of angler survey estimates can be greatly affected by the survey design and estimation approaches used. Using Monte Carlo simulation techniques, we evaluated the effects of two potential sources of bias (disproportional sampling of angler trips and subsampling of the fishing day) on two catch estimators: (1) a multiple‐day estimator that ignores day effects and pools the angler trip data over a multiple‐day period, and (2) a daily estimator that treats the trip data in each day separately. When catch rates are constant among different time periods of the fishing day, the daily estimator produces total catch estimates with little bias, whereas the multiple‐day estimator is prone to bias caused by disproportional sampling of angler trips. When catch rates vary among different periods of a fishing day, the daily estimator produces biased estimates of total catch when the fishing day is subsampled, whereas the multiple‐day estimator is less affected by the variation in daily time‐period catch rates and subsampling of fishing days. Quality of total catch and effort estimates, in terms of root mean square error and coverage probability of confidence intervals, is poor when the number of days sampled each month is low and fishing days are subsampled.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141929/1/tafs0234.pd