Display of probability densities for data from a continuous distribution

Based on cumulative distribution functions, Fourier series expansion and Kolmogorov tests, we present a simple method to display probability densities for data drawn from a continuous distribution. It is often more efficient than using histograms.Comment: 5 pages, 4 figures, presented at Computer Simulation Studies XXIV, Athens, GA, 201

A New (Old), Invasive Ant in the Hardwood Forests of Eastern North America and Its Potentially Widespread Impacts

Biological invasions represent a serious threat for the conservation of biodiversity in many ecosystems. While many social insect species and in particular ant species have been introduced outside their native ranges, few species have been successful at invading temperate forests. In this study, we document for the first time the relationship between the abundance of the introduced ant, Pachycondyla chinensis, in mature forests of North Carolina and the composition, abundance and diversity of native ant species using both a matched pair approach and generalized linear models. Where present, P. chinensis was more abundant than all native species combined. The diversity and abundance of native ants in general and many individual species were negatively associated with the presence and abundance of P. chinensis. These patterns held regardless of our statistical approach and across spatial scales. Interestingly, while the majority of ant species was strongly and negatively correlated with the abundance and presence of P. chinensis, a small subset of ant species larger than P. chinensis was either as abundant or even more abundant in invaded than in uninvaded sites. The large geographic range of this ant species combined with its apparent impact on native species make it likely to have cascading consequences on eastern forests in years to come, effects mediated by the specifics of its life history which is very different from those of other invasive ants. The apparent ecological impacts of P. chinensis are in addition to public health concerns associated with this species due to its sometimes, deadly sting

Measurement of the Generalized Polarizabilities of the Proton in Virtual Scattering at Q2=0.92 and 1.76 GeV2: I. Low Energy Expansion Analysis

Virtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility at low Center-of-Mass energies, below pion threshold. Following the Low Energy Theorem for the $ep \to ep \gamma$ process, we obtain values for the two structure functions Pll-Ptt/epsilon and Plt at four-momentum transfer squared Q2=0.92 and 1.76 GeV2.Comment: 4 pages, 2 figures, to be submitted to PRL. Figs 1 and 2, lettering enlarge

Radiation tail in (e,e ` p) reactions and corrections to experimental data

We present a direct calculation of the cross section for the reaction He-3(e,e’p) including the radiation tail originating from bremsstrahlung processes. This calculation is compared to measured cross sections. The calculation is carried out from within a Monte Carlo simulation program so that acceptance-averaging effects, along with a subset of possible energy losses, are taken into account. Excellent agreement is obtained between our calculation and measured data, after a correction factor fur higher-order bremsstrahlung is devised and applied to the tail. Industry-standard radiative corrections fail fur these data, and we use the results of our calculation to dissect the failure. Implications for design and analysis of experiments in the Jefferson-Laboratory energy domain are discussed

Measurement of the induced proton polarization P-n in the C-12(e,e `(p)over-right-arrow) reaction

The first measurements of the induced proton polarization P-n for the C-12(e,e’(p) over right arrow) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (w, q) approximate to (294 MeV, 756 MeV/c) and sampled a missing momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data fur the 1p(3/2) shelf. The data for the continuum suggest that both the 1s(1/2) shell and underlying l > 1 configurations contribute

Search for quadrupole strength in the electroexcitation of the Delta(+)(1232)

High-precision H(e,e\u27p)pi0 measurements at Q2=0.126 (GeV/c)2 are reported, which allow the determination of quadrupole amplitudes in the gamma* N-\u3eDelta transition; they simultaneously test the reliability of electroproduction models. The derived quadrupole-to-dipole amplitude ratios, Rsm=(-6.5 +- 0.2{stat+sys} +- 2.5{mod}) % and Rem=(-2.1 +- 0.2{stat+sys} +- 2.0{mod}) %, are dominated by model error. Previous Rsm and Rem results should be reconsidered after the model uncertainties associated with the method of their extraction are taken into account

Measurement of recoil proton polarizations in the electrodisintegration of deuterium by polarized electrons

In order to test modem theories of two-nucleon bound and scattering states, we have measured the spin polarization of ejectile protons in the electrodisintegration reaction d((e) over right arrow, e’(p) over right arrow)n. Compared with spin-averaged observations, these observables offer the potential of enhanced sensitivity to details of the reaction process. The experiment was carried out in quasielastic kinematics (q(mu)q(mu)= -2m(p) omega= -0.38GeV(2)/c(2)). Protons were detected at two angles corresponding to neutron recoil momenta p(r) of 0 and 100MeV/c. Full nonrelativistic calculations of the polarization transfer components s(l) and s(t), including leading order relativistic contributions, describe our measurements well, but calculations of the induced polarization s(n) at p(r) = 100 MeV/c underpredict the experimental result. (C) 1999 Published by Elsevier Science B.V. All rights reserved

Measurement of R=σL/σT and the separated longitudinal and transverse structure functions in the nucleon-resonance region

We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.

Dispersive corrections in elastic electron-nucleus scattering: an investigation in the intermediate energy regime and their impact on the nuclear matter

International audienceMeasurements of elastic electron scattering data within the past decade have highlighted two-photon exchange contributions as a necessary ingredient in theoretical calculations to precisely evaluate hydrogen elastic scattering cross sections. This correction can modify the cross section at the few percent level. In contrast, dispersive effects can cause significantly larger changes from the Born approximation. The purpose of this experiment is to extract the carbon-12 elastic cross section around the first diffraction minimum, where the Born term contributions to the cross section are small to maximize the sensitivity to dispersive effects. The analysis uses the LEDEX data from the high resolution Jefferson Lab Hall A spectrometers to extract the cross sections near the first diffraction minimum of $^{12}$C at beam energies of 362 MeV and 685 MeV. The results are in very good agreement with previous world data, although with less precision. The average deviation from a static nuclear charge distribution expected from linear and quadratic fits indicate a 30.6% contribution of dispersive effects to the cross section at 1 GeV. The magnitude of the dispersive effects near the first diffraction minimum of $^{12}$C has been confirmed to be large with a strong energy dependence and could account for a large fraction of the magnitude for the observed quenching of the longitudinal nuclear response. These effects could also be important for nuclei radii extracted from parity-violating asymmetries measured near a diffraction minimum

Erratum to: Dispersive corrections in elastic electron-nucleus scattering: an investigation in the intermediate energy regime and their impact on the nuclear matter (The European Physical Journal A, (2020), 56, 5, (126), 10.1140/epja/s10050-020-00135-7)

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