380 research outputs found

    First Leptonic Probe of Neutron Radii in Lead at Low-Q2

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    Over the past decade, in Hall-A of the Thomas Jefferson National Accelerator Facility (TJNAF), both the HAPPEX and PREx collaborations have carried out various high-precision polarized elastic electron scattering experiments to explore the nuclear structure, the nucleon form factor and the weak charge of proton and electron. They have done so through the technique of the parity-violating asymmetry measurement with limited theoretical uncertainties. My dissertation focuses on the study of nuclear structure, namely the thickness of the neutron skin, using elastic electron scattering experiments. The direct measurement of the thickness of the neutron skin in heavy nuclei, where neutron are two-fold more than protons, constrains the slope of changes in binding energies of every single heavy nucleus with respect to the full nucleus density, including proton and neutron densities. In addition, a more precise description of the neutron density profile for each heavy nucleus can help us gain better understanding of nuclear binding energies and has astrophysical implications for neutron stars. As far as we know, the proton and charge RMS (root-mean-square) radii in heavy nuclei such as Lead (208/82 Pb) have been measured with an accuracy of 0.02 fm and 0.002 fm, respectively. However, there is no clear picture of the neutron density profile through a high precision neutron RMS radii measurement free from the strong interaction until now. Through a series simulations, both theorists and experimentalists have studied the sensitivity of the parity-violating asymmetry to the extraction of the neutron radii in heavy nuclei. Under some specific conditions, for instance, a fixed scattering angle of 5 degrees and a fixed Q2 of 0.0088 GeV2, a 3% statistic uncertainty of parity-violating asymmetries corresponds to a merely 1% error of the neutron radii in Lead (208/82 Pb). That is, the uncertainties of neutron radii in Lead (208/82 Pb) is three-fold smaller than the error of the parity-violating asymmetry. Since Mar. 2010, we performed the first electroweak experiment to probe the neutron radii in Lead (208/82 Pb). The normalized parity-violating asymmetries, after addressing false asymmetries, background asymmetries, to the 90% partially polarized electron beam and the momentum-transfer (Q2) is 0.656 ± 0.06(stat) ± 0.014(sys) ppm (part-per-million), which corresponds to the thickness of the neutron skin of 0.33+0.16/-0.18 fm. One of the most significant systematic uncertainties results from the discrepancies in beam parameters such as position, angle and energy on the target, leading to the difference in the differential cross-section between two helicity states. The helicity-correlated (window-to-window or pulse-to-pulse) beam asymmetries thus arise. My primary contribution to this experiment is to establish an analysis strategy used to control the size of the helicity-correlated beam asymmetries during the data-taking period. This analysis is especially addressed in Chapter 6. In sum, the neutron radii of 0.33+0.16/-0.18 fm in Lead (208/82 Pb) supports the existence of the neutron skin in the neutron-rich matter. A second future run will yield a much higher precision neutron radii measurement. Moreover, the strong correlation between the neutron skin in Lead (208/82 Pb) and the neutron start radius indicates an approach from nuclear physics to understand the astrophysical equation of state (EOS) for a neutron star

    Comparison of the calorimetric and kinematic methods of neutrino energy reconstruction in disappearance experiments

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    To be able to achieve their physics goals, future neutrino-oscillation experiments will need to reconstruct the neutrino energy with very high accuracy. In this work, we analyze how the energy reconstruction may be affected by realistic detection capabilities, such as energy resolutions, efficiencies, and thresholds. This allows us to estimate how well the detector performance needs to be determined a priori in order to avoid a sizable bias in the measurement of the relevant oscillation parameters. We compare the kinematic and calorimetric methods of energy reconstruction in the context of two muon-neutrino disappearance experiments operating in different energy regimes. For the calorimetric reconstruction method, we find that the detector performance has to be estimated with a ~10% accuracy to avoid a significant bias in the extracted oscillation parameters. On the other hand, in the case of kinematic energy reconstruction, we observe that the results exhibit less sensitivity to an overestimation of the detector capabilities.Comment: 16 pages, 14 figures, matches the version published in Phys. Rev.

    Effective Radiotherapy Cured Cauda Equina Syndrome Caused by Remitted Intracranial Germinoma Depositing

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    Cauda equina syndrome (CES) in children is very rare and can permanently disable. A remitted intracranial germinoma depositing on the spinal cord, leading to CES, has never been reported. We discuss the case of a 10-year-old girl who presented with sudden ataxia, low back pain, sensory deficits of the left lower extremity, and difficulty urinating and defecating 7 months after totally remitted intracranial germinoma postintracranial surgery and cranial irradiation. Magnetic resonance imaging (MRI) of the brain and spine showed multiple intradural extramedullary homogeneous masses from the cervical to lumbar levels, compressing the conus medullaris and cauda equina. After emergent craniospinal irradiation, the patient's neurologic symptoms dramatically subsided. A remitted intracranial germinoma depositing on her spinal cord could be the cause of CES. Early identification and a proper craniospinal irradiation may halt the progression of symptoms

    Transmission of acute infectious illness among cases of Kawasaki disease and their household members

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    Background/purposeKawasaki disease (KD) is a disease of unknown cause and the causative agent is most likely to be infectious in nature. To investigate the household transmission pattern of infectious illness and etiology, we thus initiated a prospective case and household study.MethodsWe enrolled KD cases and their household members from February 2004 to September 2008. The KD cases and their household members accepted questionnaire-based interviews of the contact history, signs of infection, and symptoms to check whether clusters of infectious illness occurred.ResultsA total of 142 KD cases and 561 household members were enrolled. Among the 142 KD cases, 136 cases (96%) were typical KD, and six (4%) were atypical KD. Of the 561 household members, 17% were siblings, 46% were parents, 18% were grandparents, and the others were cousins or babysitters. Prior to the onset of their KD illness, 66% (94/142) KD cases had contact with ill household members. On the same day of the onset of KD cases' illness, 4% (6/142) KD cases had household members with illness. After KD cases' disease onset, 70% (100/142) KD cases had at least one other family member with illness. Overall, 61% (343/561) of all the household members had acute infectious illness during KD cases' acute stage, and 92% (130/142) of the families had clusters of infectious illness.ConclusionA total of 66% KD cases had positive contact with ill household members prior to their disease onset and 92% of families had clusters of infectious illness, so KD is strongly associated with infections

    Extract from Periostracum cicadae

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    Periostracum cicadae is widely used for the treatment of skin diseases such as eczema, pruritus, and itching. The current study sought to evaluate the effect of P. cicadae extract on ultraviolet B (UVB) irradiation and identify the mechanisms involved. Photodamage-protective activity of P. cicadae extracts against oxidative challenge was screened using HaCaT keratinocytes. P. cicadae extracts did not affect cell viability but decreased reactive oxygen species (ROS) production. The extract attenuates the expression of interleukin-6 (IL-6), matrix metalloproteinase-2 (MMP-2), and MMP-9 in UVB-treated HaCaT cells. Also, P. cicadae abrogated UVB-induced activation of NF-κB, p53, and activator protein-1 (AP-1). The downmodulation of IL-6 by P. cicadae was inhibited by the p38 inhibitor (SB203580) or JNK inhibitor (SP600125). Moreover, the extract attenuated the expression of NF-κB and induced thrombomodulin in keratinocytes and thereby effectively downregulated inflammatory responses in the skin. The nuclear accumulation and expression of NF-E2-related factor (Nrf2) were increased by P. cicadae treatment. Furthermore, treatment with P. cicadae remarkably ameliorated the skin’s structural damage induced by irradiation. This study demonstrates that P. cicadae may protect skin cells against oxidative insult by modulating ROS concentration, IL-6, MMPs generation, antioxidant enzymes activity, and cell signaling pathways

    Effect of Surface Geology on Ground Motions: The Case of Station TAP056 - Chutzuhu Site

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    In the Tatun mountain area of northern Taiwan are two strong motion stations approximately 2.5 km apart, TAP056 and TAP066 of the TSMIP network. The accelerometer at station TAP056 is often triggered by earthquakes, but that at TAP066 station is not. Comparisons of vertical and horizontal peak ground accelerations reveal PGA in the vertical, east-west, and north-south components at TAP056 station to be 3.89, 7.57, and 5.45 times those at station TAP066, respectively. The PGA ratio does not seem to be related to earthquake source or path. Fourier spectra of earthquake records at station TAP056 always have approximately the same dominant frequency; however, those at station TAP066 are different due to different sources and paths of different events. This shows that spectra at TAP056 station are mainly controlled by local site effects. The spectral ratios of TAP056/TAP066 show the S-wave is amplified at around 8 ~ 10 Hz. The horizontal/vertical spectral ratios of station TAP056 also show a dominant frequency at about 6 and 8 ~ 10 Hz. After dense microtremor surveying and the addition of one accelerometer just 20 meters away from the original observation station, we can confirm that the top soft soil layer upon which the observation station is constructed generates the local site response at station TAP056

    Serologic Status for Pandemic (H1N1) 2009 Virus, Taiwan

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    We studied preexisting immunity to pandemic (H1N1) 2009 virus in persons in Taiwan. A total of 18 (36%) of 50 elderly adults in Taiwan born before 1935 had protective antibodies against currently circulating pandemic (H1N1) 2009 virus. Seasonal influenza vaccines induced antibodies that did not protect against pandemic (H1N1) 2009 virus
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