871 research outputs found

    The Structure of the Nucleon: Elastic Electromagnetic Form Factors

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    Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. Accurate experimental measurements of the nucleon form factors are a test-bed for understanding how the nucleon's static properties and dynamical behavior emerge from QCD, the theory of the strong interactions between quarks. There has been enormous theoretical progress, since the publication of the Jefferson Lab proton form factor ratio data, aiming at reevaluating the picture of the nucleon. We will review the experimental and theoretical developments in this field and discuss the outlook for the future.Comment: arXiv admin note: text overlap with arXiv:1301.0905, arXiv:hep-ph/0609004, arXiv:1411.6908 by other author

    Nucleon Electromagnetic Form Factors

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    There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations

    AN OVERVIEW OF OBSERVATIONAL SLEEP RESEARCH WITH APPLICATION TO SLEEP STAGE TRANSITIONING

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    In this manuscript we give an overview of observational sleep research with a particular emphasis on sleep stage transitions. Sleep states represent a categorization of sleep electroencephalogram behavior over the night. We postulate that the rate of transitioning between sleep states is an important predictor of health. This claim is evaluated by comparing subjects with sleep disordered breathing to matched controls

    Progress in Diarrheal Disease Research at Namru-2 in Collaboration with Badan Litbangkes and Rspi

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    Penyakit diare termasuk kolera masih merupakan masalah kesehatan yang penting untuk Indonesia. Kejadian luar biasa (KLB) "muntah-berak" masih terus dilaporkan dari berbagai daerah di Indonesia. Salah satu upaya yang dilakukan untuk mengatasi keadaan ini adalah menemukan suatu vaksin yang aman, praktis dan terjangkau harganya. CVD-103 adalah strain V. cholerae yang sebagian besar gen penyebab diare, toksin subunit A, telah dibuang. Pada penelitian dengan peserta anak-anak di Jakarta, CVD 103-HgR ternyata memberikan kenaikan antibodi dan dapat diterima baik oleh anak-anak Indonesia berusia 5-9 tahun dan 25-59 bulan. Di samping itu pemeriksaan sampel bakteriologik dari lingkungan dekat tempat kediaman peserta dengan menggunakan teknik yang peka untuk mendeteksi V. cholerae, tidak menemukan adanya strain vaksin. Suatu penelitian lapangan dengan tujuan untuk menilai kemanjuran dosis tunggal vaksin oral kolera CVD 103-HgR untuk pencegahan kolera secara klinis selama tiga tahun, telah dimulai didaerah Jakarta Utara pada tahun 1993. Selain itu penelitian ini juga bertujuan untuk menetapkan kemanjuran vaksin terhadap berbagai kelompok umur, terhadap kolera berat, serta membandingkan kemanjurannya pada peserta dengan golongan darah O. Jumlah penduduk yang ikut dalam penilaian vaksin ini adalah 67.000 peserta sukarela. Hasil penelitian ini diharapkan dapat diketahui pada akhir tahun 1996.Di samping penelitian tentang vaksin kolera, NAMRU dan Badan Litbangkes juga telah ikut serta dalam berbagai penelitian WHO, misalnya tentang larutan garam oralit (ORS) yang dilakukan di RS Karantina/RS Penyakit Infeksi Prof. Dr. Sulianti Saroso. Salah satu penelitian terakhir adalah manfaat larutan ORS dengan osmolaritas rendah pada tahun 1994. Hasil penelitian ini telah mendorong WHO untuk melaksanakan penelitian dengan larutan yang sama di berbagai pusat penelitian (multicenter) pada tahun 1995 sebelum mengusulkan suatu Perubahan formulasi larutan ORS secara global

    Dye-sensitized Photo-oxygenation of Nitrofurazone by Singlet Oxygen

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    Dye-sensitized photo-oxygenation of nitrofurazone by singlet oxygen has been carried out under various reaction conditions, including changes in solvents and sensitizers. The product has been isolated and characterized by elemental analysis, physical, chemical and spectral data. A suitable mechanism has been proposed for the formation of photoproduct. To confirm the participation of singlet oxygen in the reaction, singlet oxygen scavengers have been used in the photo-oxygenation reaction

    Association between Sleep Duration and 24-Hour Urine Free Cortisol in the MrOS Sleep Study

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    Context Short sleep duration is associated with adverse health outcomes, but the mechanisms involved are unknown. It has been postulated that short sleep duration may elevate cortisol levels, but studies have had conflicting results. It is unclear whether these differing findings may be due to methodological issues, such as assessment of sleep duration. Specifically, objective versus subjective methods of measuring habitual sleep duration may account for the conflicting results found in epidemiological studies. Objective: Our goal was to determine whether habitual sleep duration, measured objectively (by actigraphy) and subjectively (by self-report), was associated with 24-hour urine free cortisol (UFC), a measure of integrated cortisol secretion. Our secondary goal was to determine whether slow wave sleep (SWS, determined by polysomnography) was associated with 24-hour UFC. Design/Setting Cross sectional study of community dwelling older men. Patients/Participants 325 men (mean age = 76.6 years, SD = 5.5) from the Portland site of the MrOS Sleep Study, who underwent 24-hour urine collection, polysomnography, actigraphy and sleep questionnaire. Primary Outcome 24-hour UFC. Results: In this study of community dwelling older men, self-reported sleep duration was inversely related to 24-hour UFC levels. Participants reporting 5 to 8 hours of habitual sleep. However, sleep duration determined by actigraphy was not associated with 24-hour UFC in either univariable or multivariable regression models. SWS was not associated with 24-hour UFC. Conclusion: Objectively measured (i.e., actigraphic) sleep duration is not associated with 24-hour UFC in these community dwelling older men. This finding, together with prior studies, suggests that elevated levels of integrated cortisol secretion is not the mechanisms by which short sleep duration leads to adverse health outcomes
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