182 research outputs found

    Closing the Food Gap in Adams County: A Proposal for Comprehensive Solutions through Community Action

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    Today, in Adams County, we have two food systems. The 20% who live in poverty survive on food stamps, the food pantry, church donations, and trips to discount food vendors. Those with more financial stability could choose from an abundance of healthy, sustainably produced, local and international foods. We have come to accept these two food systems as the norm without critically analyzing how it is affecting individuals and the health of our communities. In addition to reducing the disparity and closing the food gap, this initiative is focused on building our local economy and educating our community about nutrition and the benefit of local foods in order to promote a more sustainable social, environmental and economic future. This paper begins an investigation of community food security in Adams County and makes recommendations to start the process of finding stronger community solutions. The data represented here is drawn from community discussions and programmatic statistics. It is an initial assessment to be followed up by a more comprehensive study and analysis

    Quasi-free Compton Scattering and the Polarizabilities of the Neutron

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    Differential cross sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48 cm ⊘\oslash ×\times 64 cm NaI(Tl) photon detector and the G\"ottingen SENECA recoil detector. The data cover photon energies ranging from 200 MeV to 400 MeV at θγLAB=136.2∘\theta^{LAB}_\gamma=136.2^\circ. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction p(γ,π+n)p(\gamma,\pi^+ n). The "free" proton Compton scattering cross sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross section for free scattering from quasi-free data. Differential cross sections on the free neutron have been extracted and the difference of the electromagnetic polarizabilities of the neutron have been obtained to be α−β=9.8±3.6(stat)12.1.1(syst)±2.2(model)\alpha-\beta= 9.8\pm 3.6(stat){}^{2.1}_1.1(syst)\pm 2.2(model) in units 10−4fm310^{-4}fm^3. In combination with the polarizability sum α+β=15.2±0.5\alpha +\beta=15.2\pm 0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, αn=12.5±1.8(stat)−0.6+1.1±1.1(model)\alpha_n=12.5\pm 1.8(stat){}^{+1.1}_{-0.6}\pm 1.1(model) and βn=2.7∓1.8(stat)−1.1+0.6(syst)∓1.1(model)\beta_n=2.7\mp 1.8(stat){}^{+0.6}_{-1.1}(syst)\mp 1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be γπ(n)=(58.6±4.0)×10−4fm4\gamma^{(n)}_\pi=(58.6\pm 4.0)\times 10^{-4}fm^4

    Neutron polarizabilities investigated by quasi-free Compton scattering from the deuteron

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    Measuring Compton scattered photons and recoil neutrons in coincidence, quasi-free Compton scattering by the neutron has been investigated at MAMI (Mainz) at thetaγlab=136otheta^{lab}_\gamma=136^o in an energy range from 200 to 400 MeV. From the data a polarizability difference of αn−βn=9.8±3.6(stat)−1.1+2.1(syst)±2.2(model)\alpha_n - \beta_n = 9.8 \pm 3.6(stat)^{+2.1}_{-1.1}(syst)\pm 2.2(model) in units of 10−4fm310^{-4}fm^3 has been determined. In combination with the polarizability sum αn+βn=15.2±0.5\alpha_n+\beta_n= 15.2\pm 0.5 deduced from photo absorption data, the neutron electric and magnetic polarizabilities, αn=12.5±1.8(stat)−0.6+1.1(syst)±1.1(model)\alpha_n=12.5\pm 1.8(stat)^{+1.1}_{-0.6}(syst)\pm 1.1(model) and βn=2.7∓1.8(stat)−1.1+0.6(syst)∓1.1(model)\beta_n = 2.7\mp 1.8(stat)^{+0.6}_{-1.1}(syst)\mp 1.1(model), are obtained

    Atomic-scale modeling of the deformation of nanocrystalline metals

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    Nanocrystalline metals, i.e. metals with grain sizes from 5 to 50 nm, display technologically interesting properties, such as dramatically increased hardness, increasing with decreasing grain size. Due to the small grain size, direct atomic-scale simulations of plastic deformation of these materials are possible, as such a polycrystalline system can be modeled with the computational resources available today. We present molecular dynamics simulations of nanocrystalline copper with grain sizes up to 13 nm. Two different deformation mechanisms are active, one is deformation through the motion of dislocations, the other is sliding in the grain boundaries. At the grain sizes studied here the latter dominates, leading to a softening as the grain size is reduced. This implies that there is an ``optimal'' grain size, where the hardness is maximal. Since the grain boundaries participate actively in the deformation, it is interesting to study the effects of introducing impurity atoms in the grain boundaries. We study how silver atoms in the grain boundaries influence the mechanical properties of nanocrystalline copper.Comment: 10 pages, LaTeX2e, PS figures and sty files included. To appear in Mater. Res. Soc. Symp. Proc. vol 538 (invited paper). For related papers, see http://www.fysik.dtu.dk/~schiotz/publist.htm

    Quasi-free π0\pi^0 Photoproduction from the Bound Nucleon

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    Differential cross-sections for quasi-free π0\pi^0 photoproduction from the proton and neutron bound in the deuteron have been measured for Eγ=200−400E_\gamma= 200 - 400 MeV at θγlab=136.2∘\theta^{\rm lab}_\gamma = 136.2^\circ usind the Glasgow photon tagger at MAMI, the Mainz 48 cm ∅\varnothing ×\times 64 cm NaI(Tl) photon detector and the G\"ottingen SENECA recoil detector. For the proton measurements made with both liquid deuterium and liquid hydrogen targets allow direct comparison of "free" π0\pi^0 photoproduction cross-sections as extracted from the bound proton data with experimental free cross sections which are found to be in reasonable agreement below 320 MeV. At higher energies the "free" cross sections extracted from quasifree data are significantly smaller than the experimental free cross sections and theoretical predictions based on multipole analysis. For the first time, "free" neutron cross sections have been extracted in the Δ\Delta-region. They are also in agreement with the predictions from multipole analysis up to 320 MeV and significantly smaller at higher photon energies

    Fabrication and characterization of dual function nanoscale pH-scanning ion conductance microscopy (SICM) probes for high resolution pH mapping

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    The easy fabrication and use of nanoscale dual function pH-scanning ion conductance microscopy (SICM) probes is reported. These probes incorporate an iridium oxide coated carbon electrode for pH measurement and an SICM barrel for distance control, enabling simultaneous pH and topography mapping. These pH-SICM probes were fabricated rapidly from laser pulled theta quartz pipets, with the pH electrode prepared by in situ carbon filling of one of the barrels by the pyrolytic decomposition of butane, followed by electrodeposition of a thin layer of hydrous iridium oxide. The other barrel was filled with an electrolyte solution and Ag/AgCl electrode as part of a conductance cell for SICM. The fabricated probes, with pH and SICM sensing elements typically on the 100 nm scale, were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and various electrochemical measurements. They showed a linear super-Nernstian pH response over a range of pH (pH 2–10). The capability of the pH-SICM probe was demonstrated by detecting both pH and topographical changes during the dissolution of a calcite microcrystal in aqueous solution. This system illustrates the quantitative nature of pH-SICM imaging, because the dissolution process changes the crystal height and interfacial pH (compared to bulk), and each is sensitive to the rate. Both measurements reveal similar dissolution rates, which are in agreement with previously reported literature values measured by classical bulk methods

    Measurements of 12C(→γ,pp) photon asymmetries for Eγ= 200–450 MeV

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    The 12C (→γ ,pp) reaction has been studied in the photon energy range 200-450 MeV at the Mainz microtron MAMI-C, where linearly polarised photons were energy-tagged using the Glasgow-Mainz Tagged Photon Spectrometer and protons were detected in the Crystal Ball detector. The photon asymmetry Σ has been measured over a wider Eγ range than previous measurements. The strongest asymmetries were found at low missing energies where direct emission of nucleon pairs is expected. Cuts on the difference in azimuthal angles of the two ejected protons increased the magnitude of the observed asymmetries. At low missing energies the Σ data exhibit a strong angular dependence, similar to deuteron photodisintegration
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