Towards Quantum Superpositions of a Mirror: an Exact Open Systems Analysis - Calculational Details

We give details of calculations analyzing the proposed mirror superposition experiment of Marshall, Simon, Penrose, and Bouwmeester within different stochastic models for state vector collapse. We give two methods for exactly calculating the fringe visibility in these models, one proceeding directly from the equation of motion for the expectation of the density matrix, and the other proceeding from solving a linear stochastic unravelling of this equation. We also give details of the calculation that identifies the stochasticity parameter implied by the small displacement Taylor expansion of the CSL model density matrix equation. The implications of the two results are briefly discussed. Two pedagogical appendices review mathematical apparatus needed for the calculations.Comment: 9 pages, LaTeX. Minor changes mad

Inverse correlations for multiple time series and Gaussian random fields and measures of their linear determinism

For a discrete-time vector linear stationary process, {X(t)}, admitting forward and backward autoregressive representations, the variance matrix of an optimal linear interpolator of X(t), based on a knowledge of {X(t-j), j?0}, is known to be given by Ri(0)-1 where Ri(0) denotes the inverse variance of the process. Let A=Is-1Ri(0)?1R(0)?1, where R(0) denotes the variance matrix of {X(t)} and Is an sXs, identity matrix. A measure of linear interpolability of the process, called an index of linear determinism, may be constructed from the determinant Det[Is - A], of Is - A = Ri(0)-1 R(0)-1. An alternative measure is constructed by relating tr[Ri(0)-1] the trace of Ri(0)-1, to tr[R(0)]. The relationship between the matrix A and the corresponding matrix, P, obtained by considering only an optimal one-step linear predictor of X(t) from a knowledge of its infinite past, {X(t-j),j>0}, is also discussed. The possible role the inverse correlation function may have for model specification of a vector ARMA model is explored. Close parallels between the problem of interpolation for a stationary univariate two-dimensional Gaussian random field and time series are examined and an index of linear determinism for the latter class of processes is also defined. An application of this index for model specification and diagnostic testing of a Gaussian Markov Random Field is investigated together with the question of its estimation from observed data. Results are illustrated by a simulation study

Estimating Technical Efficiency through Reduced Rank Regression

EnIn this paper we develop a statistical approach for verifying the possibility of substituting joint production frontier with single-output specification by means of Reduced Rank Regression (RRR) Our work introduces the multivariate model in the RRR framework which allows us to verify the unitary rank of the regression coefficient matrix. If the rank is one it is possible to express the production frontier in terms of aggregated output through an econometric model. Firm-specific efficiency is also measured

Comparing unconstrained parametrization methods for return covariance matrix prediction

Forecasting covariance matrices is a difficult task in many research fields since the predicted matrices should be at least positive semidefinite. This problem can be overcome by including constraints in the predictive model or through a parametrization of the matrices to be predicted. In this paper, we focus on the latter approach in a financial application and analyse four parametrizations of the covariance matrices of asset returns. The aim of the manuscript is to understand if the parametrizations of the covariance matrices exhibit differences in terms of predictive accuracy. To this end, we critically analyse their predictive performance through both a Monte Carlo simulation and an empirical application with daily and weekly realized covariance matrices of stock assets. Our findings highlight that the Cholesky decomposition and the parametrization recently introduced by Archakov and Hansen are the overall best-performing methods in terms of forecasting accuracy

Towards Quantum Superpositions of a Mirror: an Exact Open Systems Analysis

We analyze the recently proposed mirror superposition experiment of Marshall, Simon, Penrose, and Bouwmeester, assuming that the mirror's dynamics contains a non-unitary term of the Lindblad type proportional to -[q,[q,\rho]], with q the position operator for the center of mass of the mirror, and \rho the statistical operator. We derive an exact formula for the fringe visibility for this system. We discuss the consequences of our result for tests of environmental decoherence and of collapse models. In particular, we find that with the conventional parameters for the CSL model of state vector collapse, maintenance of coherence is expected to within an accuracy of at least 1 part in 10^{8}. Increasing the apparatus coupling to environmental decoherence may lead to observable modifications of the fringe visibility, with time dependence given by our exact result.Comment: 4 pages, RevTeX. Substantial changes mad

Many-body physics in the NISQ era: quantum programming a discrete time crystal

Recent progress in the realm of noisy, intermediate scale quantum (NISQ) devices represents an exciting opportunity for many-body physics, by introducing new laboratory platforms with unprecedented control and measurement capabilities. We explore the implications of NISQ platforms for many-body physics in a practical sense: we ask which {\it physical phenomena}, in the domain of quantum statistical mechanics, they may realize more readily than traditional experimental platforms. As a particularly well-suited target, we identify discrete time crystals (DTCs), novel non-equilibrium states of matter that break time translation symmetry. These can only be realized in the intrinsically out-of-equilibrium setting of periodically driven quantum systems stabilized by disorder induced many-body localization. While precursors of the DTC have been observed across a variety of experimental platforms - ranging from trapped ions to nitrogen vacancy centers to NMR crystals - none have \emph{all} the necessary ingredients for realizing a fully-fledged incarnation of this phase, and for detecting its signature long-range \emph{spatiotemporal order}. We show that a new generation of quantum simulators can be programmed to realize the DTC phase and to experimentally detect its dynamical properties, a task requiring extensive capabilities for programmability, initialization and read-out. Specifically, the architecture of Google's Sycamore processor is a remarkably close match for the task at hand. We also discuss the effects of environmental decoherence, and how they can be distinguished from `internal' decoherence coming from closed-system thermalization dynamics. Already with existing technology and noise levels, we find that DTC spatiotemporal order would be observable over hundreds of periods, with parametric improvements to come as the hardware advances.Comment: v2: added appendices B and C, added Fig.1, expanded discussio

Influencia de la posición de las malezas sobre el cultivo de sorgo granífero

Se presentan los resultados de dos ensayos donde se evaluaron las modificaciones que sobre el rendimiento del sorgo granífero, provocan las malezas según su posición y composición florística. Las mayores variaciones de rendimiento se debieron a la posición de las malezas. Cuando la comunidad fue con predominancia de dicotiledóneas. la presencia de malezas en una banda de 45 cm entre las hileras, provocó los mismos daños que en el testigo enmalezado; mientras que cuando hubo predominancia de gramíneas esos daños fueron distintos. La maleza ubicada en una banda de 25 cm en la línea de siembra fue menos agresiva y con efecto similar en ambos casos. Los componentes que más se modificaron fueron el número de panojas y el tamaño de las mismas.Dirección: Oscar Rubiolo y Fernando García, Frof. Asoc. y Adj. de Cerealicultura y Terapéutica vegetal, respectivamente

Mobile Phone Interventions for Adolescent Sexual and Reproductive Health: A Systematic Review

CONTEXT: Interventions for adolescent sexual and reproductive health (ASRH) are increasingly using mobile phones but may not effectively report evidence. OBJECTIVE: To assess strategies, findings, and quality of evidence on using mobile phones to improve ASRH by using the mHealth Evidence Reporting and Assessment (mERA) checklist recently published by the World Health Organization mHealth Technical Evidence Review Group. DATA SOURCES: Systematic searches of 8 databases for peer-reviewed studies published January 2000 through August 2014. STUDY SELECTION: Eligible studies targeted adolescents ages 10 to 24 and provided results from mobile phone interventions designed to improve ASRH. DATA EXTRACTION: Studies were evaluated according to the mERA checklist, covering essential mHealth criteria and methodological reporting criteria. RESULTS: Thirty-five articles met inclusion criteria. Studies reported on 28 programs operating at multiple levels of the health care system in 7 countries. Most programs (82%) used text messages. An average of 41% of essential mHealth criteria were met (range 14%-79%). An average of 82% of methodological reporting criteria were met (range 52%-100%). Evidence suggests that inclusion of text messaging in health promotion campaigns, sexually transmitted infection screening and follow-up, and medication adherence may lead to improved ASRH. LIMITATIONS: Only 3 articles reported evidence from lower- or middle-income countries, so it is difficult to draw conclusions for these settings. CONCLUSIONS: Evidence on mobile phone interventions for ASRH published in peer-reviewed journals reflects a high degree of quality in methods and reporting. In contrast, current reporting on essential mHealth criteria is insufficient for understanding, replicating, and scaling up mHealth interventions

A metaproteomic approach to study human-microbial ecosystems at the mucosal luminal interface

Aberrant interactions between the host and the intestinal bacteria are thought to contribute to the pathogenesis of many digestive diseases. However, studying the complex ecosystem at the human mucosal-luminal interface (MLI) is challenging and requires an integrative systems biology approach. Therefore, we developed a novel method integrating lavage sampling of the human mucosal surface, high-throughput proteomics, and a unique suite of bioinformatic and statistical analyses. Shotgun proteomic analysis of secreted proteins recovered from the MLI confirmed the presence of both human and bacterial components. To profile the MLI metaproteome, we collected 205 mucosal lavage samples from 38 healthy subjects, and subjected them to high-throughput proteomics. The spectral data were subjected to a rigorous data processing pipeline to optimize suitability for quantitation and analysis, and then were evaluated using a set of biostatistical tools. Compared to the mucosal transcriptome, the MLI metaproteome was enriched for extracellular proteins involved in response to stimulus and immune system processes. Analysis of the metaproteome revealed significant individual-related as well as anatomic region-related (biogeographic) features. Quantitative shotgun proteomics established the identity and confirmed the biogeographic association of 49 proteins (including 3 functional protein networks) demarcating the proximal and distal colon. This robust and integrated proteomic approach is thus effective for identifying functional features of the human mucosal ecosystem, and a fresh understanding of the basic biology and disease processes at the MLI. © 2011 Li et al