249 research outputs found

    Pionic Atom Spectroscopy in the (d,3He) reaction at finite angles

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    We study the formation of deeply bound pionic atoms in the (d,3He) reactions theoretically and show the energy spectra of the emitted 3He at finite angles, which are expected to be observed experimentally. We find that the different combinations of the pion-bound and neutron-hole states dominate the spectra at different scattering angles because of the matching condition of the reaction. We conclude that the observation of the (d,3He) reaction at finite angles will provide the systematic information of the pionic bound states in each nucleus and will help to develop the study of the pion properties and the partial restoration of chiral symmetry in nuclei.Comment: 7 pages, 4 figures, 1 tabl

    Precision spectroscopy of pionic 1s states of Sn nuclei and evidence for partial restoration of chiral symmetry in the nuclear medium

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    Deeply bound 1s states of π\pi^- in 115,119,123^{115,119,123}Sn were preferentially observed using the Sn(dd,3^3He) pion-transfer reaction under the recoil-free condition. The 1s binding energies and widths were precisely determined, and were used to deduce the isovector parameter of the s-wave pion-nucleus potential to be b1=0.115±0.007 mπ1b_1 =-0.115\pm 0.007 ~m_{\pi}^{-1}. The observed enhancement of b1|b_1| over the free πN\pi N value (b1free/b1=0.78±0.05b_1^{\rm free}/b_1 = 0.78 \pm 0.05) indicates a reduction of the chiral order parameter, fπ(ρ)2/fπ20.64f^{*}_{\pi} (\rho)^2/f_{\pi}^2 \approx 0.64, at the normal nuclear density, ρ=ρ0\rho = \rho_0.Comment: 4 pages including 3 postscript figures, RevTeX 4 with multirow.sty, submitted to Physical Review Letter

    ΛN\Lambda N correlations from the stopped KK^- reaction on 4{}^4He

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    We have investigated correlations of coincident ΛN\Lambda N pairs from the stopped KK^- reaction on 4{}^4He, and clearly observed Λp\Lambda p and Λn\Lambda n branches of the two-nucleon absorption process in the ΛN\Lambda N invariant mass spectra. In addition, non-mesonic reaction channels, which indicate possible exotic signals for the formation of strange multibaryon states, have been identified.Comment: 5 pages, 3 figures, submitted to Physical Review Letter

    A search for deeply bound kaonic nuclear states

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    We have measured proton and neutron energy spectra by stopping negative kaons on liquid helium4. Two distinct peak structures were found on both spectra, which were assigned to the formation of new kinds of strange stribaryons. In this paper, we summarize both results.Comment: 7 pages, 3 figures, HYP2003 conference proceeding

    Interannual variation in the fine-mode MODIS aerosol optical depth and its relationship to the changes in sulfur dioxide emissions in China between 2000 and 2010

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    Anthropogenic SO<sub>2</sub> emissions increased alongside economic development in China at a rate of 12.7% yr<sup>−1</sup> from 2000 to 2005. However, under new Chinese government policy, SO<sub>2</sub> emissions declined by 3.9% yr<sup>−1</sup> between 2005 and 2009. Between 2000 and 2010, we found that the variability in the fine-mode (submicron) aerosol optical depth (AOD) over the oceans adjacent to East Asia increased by 3–8% yr<sup>−1</sup> to a peak around 2005–2006 and subsequently decreased by 2–7% yr<sup>−1</sup>, based on observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA's Terra satellite and simulations by a chemical transport model. This trend is consistent with ground-based observations of aerosol particles at a mountainous background observation site in central Japan. These fluctuations in SO<sub>2</sub> emission intensity and fine-mode AOD are thought to reflect the widespread installation of fuel-gas desulfurization (FGD) devices in power plants in China, because aerosol sulfate is a major determinant of the fine-mode AOD in East Asia. Using a chemical transport model, we confirmed that the contribution of particulate sulfate to the fine-mode AOD is more than 70% of the annual mean and that the abovementioned fluctuation in fine-mode AOD is caused mainly by changes in SO<sub>2</sub> emission rather than by other factors such as varying meteorological conditions in East Asia. A strong correlation was also found between satellite-retrieved SO<sub>2</sub> vertical column density and bottom-up SO<sub>2</sub> emissions, both of which were also consistent with observed fine-mode AOD trends. We propose a simplified approach for evaluating changes in SO<sub>2</sub> emissions in China, combining the use of modeled sensitivity coefficients that describe the variation of fine-mode AOD with changes in SO<sub>2</sub> emissions and satellite retrieval. Satellite measurements of fine-mode AOD above the Sea of Japan marked a 4.1% yr<sup>−1</sup> decline between 2007 and 2010, which corresponded to the 9% yr<sup>−1</sup> decline in SO<sub>2</sub> emissions from China during the same period

    White matter alterations in Attention-Deficit/Hyperactivity Disorder (ADHD):a systematic review of 129 diffusion imaging studies with meta-analysis

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    Aberrant anatomical brain connections in attention-deficit/hyperactivity disorder (ADHD) are reported inconsistently across diffusion weighted imaging (DWI) studies. Based on a pre-registered protocol (Prospero: CRD42021259192), we searched PubMed, Ovid, and Web of Knowledge until 26/03/2022 to conduct a systematic review of DWI studies. We performed a quality assessment based on imaging acquisition, preprocessing, and analysis. Using signed differential mapping, we meta-analyzed a subset of the retrieved studies amenable to quantitative evidence synthesis, i.e., tract-based spatial statistics (TBSS) studies, in individuals of any age and, separately, in children, adults, and high-quality datasets. Finally, we conducted meta-regressions to test the effect of age, sex, and medication-naïvety. We included 129 studies (6739 ADHD participants and 6476 controls), of which 25 TBSS studies provided peak coordinates for case-control differences in fractional anisotropy (FA)(32 datasets) and 18 in mean diffusivity (MD)(23 datasets). The systematic review highlighted white matter alterations (especially reduced FA) in projection, commissural and association pathways of individuals with ADHD, which were associated with symptom severity and cognitive deficits. The meta-analysis showed a consistent reduced FA in the splenium and body of the corpus callosum, extending to the cingulum. Lower FA was related to older age, and case-control differences did not survive in the pediatric meta-analysis. About 68% of studies were of low quality, mainly due to acquisitions with non-isotropic voxels or lack of motion correction; and the sensitivity analysis in high-quality datasets yielded no significant results. Findings suggest prominent alterations in posterior interhemispheric connections subserving cognitive and motor functions affected in ADHD, although these might be influenced by non-optimal acquisition parameters/preprocessing. Absence of findings in children may be related to the late development of callosal fibers, which may enhance case-control differences in adulthood. Clinicodemographic and methodological differences were major barriers to consistency and comparability among studies, and should be addressed in future investigations. © 2023, The Author(s).11Nsciescopu
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