Fluorescence antibunching microscopy

Breaking the diffraction limit in microscopy by utilizing quantum properties of light has been the goal of intense research in the recent years. We propose a quantum superresolution technique based on non-classical emission statistics of fluorescent markers, routinely used as contrast labels for bio-imaging. The technique can be readily implemented using standard fluorescence microscopy equipment

MEXIT: Maximal un-coupling times for stochastic processes

Classical coupling constructions arrange for copies of the \emph{same} Markov process started at two \emph{different} initial states to become equal as soon as possible. In this paper, we consider an alternative coupling framework in which one seeks to arrange for two \emph{different} Markov (or other stochastic) processes to remain equal for as long as possible, when started in the \emph{same} state. We refer to this "un-coupling" or "maximal agreement" construction as \emph{MEXIT}, standing for "maximal exit". After highlighting the importance of un-coupling arguments in a few key statistical and probabilistic settings, we develop an explicit \MEXIT construction for stochastic processes in discrete time with countable state-space. This construction is generalized to random processes on general state-space running in continuous time, and then exemplified by discussion of \MEXIT for Brownian motions with two different constant drifts.Comment: 28 page

REIMR: A Process for Utilizing Propulsion-Oriented 'Lessons-Learned' to Mitigate Development Risk

This paper is a summary overview of a study conducted a t the NASA Marshall Space Flight Center (MSFC) during the initial phases of the Space Launch Initiative (SLI) program to evaluate a large number of technical problems associated with the design, development, test, evaluation and operation of several major liquid propellant rocket engine systems (i.e., SSME, Fastrac, J-2, F-1). The results of this study was the identification of the "Fundamental Root Causes" that enabled the technical problems to manifest, and practices that can be implemented to prevent them from recurring in future engine development efforts. This paper will discus the Fundamental Root Causes, cite some examples of how the technical problems arose from them, and provide a discussion of how they can be mitigated or avoided

Performance and Inbreeding Depression of Populations Representing Seven Eras of Maize Breeding

Improvements in maize (Zea mays L.) yields have been due to improvements in production inputs as well as to cultivars that have improved performance at low levels of inputs and the ability to respond to high levels of inputs used on today\u27s farms. The objectives of this study were to estimate genetic rates of gain and inbreeding depression by evaluating populations representative of each of seven eras of maize breeding. Inbred lines representative of each of the six decades (eras) from 1930 to 1980 were intermated to produce six era populations. A seventh, pre-1930 era, was represented by the open-pollinated cultivars (OP) ‘Reids Yellow Dent’ and ‘Lancaster Sure Crop’. These eight entries along with three check populations were evaluated in six Iowa environments. In addition, to assess changes in the rates of inbreeding depression, S1 bulk populations of the six era populations and OP and S2 bulks of the three check populations were also evaluated. The average genetic rate of gain for grain yield was 0.52 ± 0.04 Mg ha-1 era-1 when OP was included in the analysis. By assuming 10 yr per era, the yearly genetic rate of gain was 0.052 ± 0.004 Mg ha-1. The rates of genetic gain for percentage of stalk lodging and grain moisture at harvest were −5.1 ± 0.5% era-1 and 0.44 ± 0.09% era-1, respectively. The rate of inbreeding depression for yield increased steadily over eras, and the rate of inbreeding depression for Era 6 was double that for the OP. However, inbreeding depression as a percentage of the So mean showed no directional changes and was similar for all eras. These results indicate that breeders have been effective at selecting lines and hybrids with higher yields and resistance to lodging and the ability to produce higher yields under stress conditions. The increased rates of inbreeding depression for the more recent eras coupled with the increased performance of the S0 and S1 populations suggest that favorable allele frequencies were initially below 0.5 and have been increasing and]or that the more recent era populations are segregating at more loci

DNA: From rigid base-pairs to semiflexible polymers

The sequence-dependent elasticity of double-helical DNA on a nm length scale can be captured by the rigid base-pair model, whose strains are the relative position and orientation of adjacent base-pairs. Corresponding elastic potentials have been obtained from all-atom MD simulation and from high-resolution structural data. On the scale of a hundred nm, DNA is successfully described by a continuous worm-like chain model with homogeneous elastic properties characterized by a set of four elastic constants, which have been directly measured in single-molecule experiments. We present here a theory that links these experiments on different scales, by systematically coarse-graining the rigid base-pair model for random sequence DNA to an effective worm-like chain description. The average helical geometry of the molecule is exactly taken into account in our approach. We find that the available microscopic parameters sets predict qualitatively similar mesoscopic parameters. The thermal bending and twisting persistence lengths computed from MD data are 42 and 48 nm, respectively. The static persistence lengths are generally much higher, in agreement with cyclization experiments. All microscopic parameter sets predict negative twist-stretch coupling. The variability and anisotropy of bending stiffness in short random chains lead to non-Gaussian bend angle distributions, but become unimportant after two helical turns.Comment: 13 pages, 6 figures, 6 table

R-local Delaunay inhibition model

Let us consider the local specification system of Gibbs point process with inhib ition pairwise interaction acting on some Delaunay subgraph specifically not con taining the edges of Delaunay triangles with circumscribed circle of radius grea ter than some fixed positive real value $R$. Even if we think that there exists at least a stationary Gibbs state associated to such system, we do not know yet how to prove it mainly due to some uncontrolled "negative" contribution in the expression of the local energy needed to insert any number of points in some large enough empty region of the space. This is solved by introducing some subgraph, called the $R$-local Delaunay graph, which is a slight but tailored modification of the previous one. This kind of model does not inherit the local stability property but satisfies s ome new extension called $R$-local stability. This weakened property combined with the local property provides the existence o f Gibbs state.Comment: soumis \`{a} Journal of Statistical Physics 27 page

Ergodic transition in a simple model of the continuous double auction

We study a phenomenological model for the continuous double auction, whose aggregate order process is equivalent to two independent M/M/1 queues. The continuous double auction defines a continuous-time random walk for trade prices. The conditions for ergodicity of the auction are derived and, as a consequence, three possible regimes in the behavior of prices and logarithmic returns are observed. In the ergodic regime, prices are unstable and one can observe a heteroskedastic behavior in the logarithmic returns. On the contrary, non-ergodicity triggers stability of prices, even if two different regimes can be seen