Wigner Functions on a Lattice

The Wigner functions on the one dimensional lattice are studied. Contrary to the previous claim in literature, Wigner functions exist on the lattice with any number of sites, whether it is even or odd. There are infinitely many solutions satisfying the conditions which reasonable Wigner functions should respect. After presenting a heuristic method to obtain Wigner functions, we give the general form of the solutions. Quantum mechanical expectation values in terms of Wigner functions are also discussed.Comment: 11 pages, no figures, REVTE

USDA Forecasts Of Crop Ending Stocks: How Well Have They Performed?

This study analyzes forecasts of U.S. ending stocks for corn, soybeans, and wheat issued by the USDA. The proposed efficiency tests focus on forecast revisions. Forecast errors are decomposed into monthly unforecastable shocks and idiosyncratic residuals. The error covariance matrix allows for heteroscedasticity and auto-correlations. Results suggest that the USDA forecasts are inefficient, providing strong evidence that the USDA is conservative in forecasting the ending stocks. Unforecastable shocks are heteroscedastic, and idiosyncratic residuals are small. Results are consistent across the three decades analyzed, but soybean forecasts are found to be considerably worse from 2005 to 2015

Quantum Characterization of a Werner-like Mixture

We introduce a Werner-like mixture [R. F. Werner, Phys. Rev. A {\bf 40}, 4277 (1989)] by considering two correlated but different degrees of freedom, one with discrete variables and the other with continuous variables. We evaluate the mixedness of this state, and its degree of entanglement establishing its usefulness for quantum information processing like quantum teleportation. Then, we provide its tomographic characterization. Finally, we show how such a mixture can be generated and measured in a trapped system like one electron in a Penning trap.Comment: 8 pages ReVTeX, 8 eps figure

Optimal estimation of qubit states with continuous time measurements

We propose an adaptive, two steps strategy, for the estimation of mixed qubit states. We show that the strategy is optimal in a local minimax sense for the trace norm distance as well as other locally quadratic figures of merit. Local minimax optimality means that given $n$ identical qubits, there exists no estimator which can perform better than the proposed estimator on a neighborhood of size $n^{-1/2}$ of an arbitrary state. In particular, it is asymptotically Bayesian optimal for a large class of prior distributions. We present a physical implementation of the optimal estimation strategy based on continuous time measurements in a field that couples with the qubits. The crucial ingredient of the result is the concept of local asymptotic normality (or LAN) for qubits. This means that, for large $n$, the statistical model described by $n$ identically prepared qubits is locally equivalent to a model with only a classical Gaussian distribution and a Gaussian state of a quantum harmonic oscillator. The term `local' refers to a shrinking neighborhood around a fixed state $\rho_{0}$. An essential result is that the neighborhood radius can be chosen arbitrarily close to $n^{-1/4}$. This allows us to use a two steps procedure by which we first localize the state within a smaller neighborhood of radius $n^{-1/2+\epsilon}$, and then use LAN to perform optimal estimation.Comment: 32 pages, 3 figures, to appear in Commun. Math. Phy

A CsI(Tl) Scintillating Crystal Detector for the Studies of Low Energy Neutrino Interactions

Scintillating crystal detector may offer some potential advantages in the low-energy, low-background experiments. A 500 kg CsI(Tl) detector to be placed near the core of Nuclear Power Station II in Taiwan is being constructed for the studies of electron-neutrino scatterings and other keV-MeV range neutrino interactions. The motivations of this detector approach, the physics to be addressed, the basic experimental design, and the characteristic performance of prototype modules are described. The expected background channels and their experimental handles are discussed.Comment: 34 pages, 11 figures, submitted to Nucl. Instrum. Method

Clinical course long after atrial switch: a novel risk score for major clinical events

BackgroundPatients with transposition of the great arteries corrected by an atrial switch operation experience major clinical events during adulthood, mainly heart failure (HF) and arrhythmias, but data on the emerging risks remain scarce. We assessed the risk for events during the clinical course in adulthood, and provided a novel risk score for event-free survival.Methods and ResultsThis multicenter study observed 167 patients with transposition of the great arteries corrected by an atrial switch operation (61% Mustard procedure; age, 28 [interquartile range, 24-36] years) for 13 (interquartile range, 9-16) years, during which 16 (10%) patients died, 33 (20%) had HF events, defined as HF hospitalizations, heart transplantation, ventricular assist device implantation, or HF-related death, and 15 (9%) had symptomatic ventricular arrhythmias. Five-year risk of mortality, first HF event, and first ventricular arrhythmia increased from 1% each at age 25 years, to 6% (95% CI, 4%-9%), 23% (95% CI, 17%-28%), and 5% (95% CI, 2%-8%), respectively, at age 50 years. Predictors for event-free survival were examined to construct a prediction model using bootstrapping techniques. A prediction model combining age >30 years, prior ventricular arrhythmia, age >1 year at repair, moderate or greater right ventricular dysfunction, severe tricuspid regurgitation, and mild or greater left ventricular dysfunction discriminated well between patients at low (20%) 5-year risk (optimism-corrected C-statistic, 0.86 [95% CI, 0.82-0.90]). Observed 5- and 10-year event-free survival rates in low-risk patients were 100% and 97%, respectively, compared with only 31% and 8%, respectively, in high-risk patients.ConclusionsThe clinical course of patients undergoing atrial switch increasingly consists of major clinical events, especially HF. A novel risk score stratifying patients as low, intermediate, and high risk for event-free survival provides information on absolute individual risks, which may support decisions for pharmacological and interventional management.Cardiolog

Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let