1. |
- Alcorn, J, et al.
(author)
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Basic instrumentation for Hall A at Jefferson Lab
- 2004
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In: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 522:3, s. 294-346
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Journal article (peer-reviewed)abstract
- The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electro-and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. The central components of Hall A are two identical high resolution spectrometers, which allow the vertical drift chambers in the focal plane to provide a momentum resolution of better than 2 x 10(-4). A variety of Cherenkov counters, scintillators and lead-glass calorimeters provide excellent particle identification. The facility has been operated successfully at a luminosity well in excess of 10(38) CM-2 s(-1). The research program is aimed at a variety of subjects, including nucleon structure functions, nucleon form factors and properties of the nuclear medium. (C) 2003 Elsevier B.V. All rights reserved.
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2. |
- Beral, V, et al.
(author)
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Alcohol, tobacco and breast cancer - collaborative reanalysis of individual data from 53 epidemiological studies, including 58515 women with breast cancer and 95067 women without the disease
- 2002
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In: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 87, s. 1234-45
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Journal article (peer-reviewed)abstract
- Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58515 women with invasive breast cancer and 95067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19 - 1.45, P < 0.00001) for an intake of 35 - 44 g per day alcohol, and 1.46 (1.33 - 1.61, P < 0.00001) for greater than or equal to 45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1 % per 10 g per day, P < 0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers= 1.03, 95% CI 0.98 - 1.07, and for current smokers=0.99, 0.92 - 1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver. (C) 2002 Cancer Research UK.
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3. |
- Wijesooriya, K, et al.
(author)
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Polarization measurements in high-energy deuteron photodisintegration
- 2001
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In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 86:14, s. 2975-2979
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Journal article (peer-reviewed)abstract
- We present measurements of the recoil proton polarization for the d(γ⃗,p⃗)n reaction at θc.m. = 90° for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization py vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(γ,p)ncross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.
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4. |
- Gao, Y. L., et al.
(author)
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Crystal structure and electrochemical behavior of copper complex with 6-hydroxymethyl-substituted tris(2-pyridylmethyl) amine, CuCl(C19H20N4O) ClO4
- 2004
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In: Chinese journal of structural chemistry. - 0254-5861. ; 23:11, s. 1262-1265
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Journal article (peer-reviewed)abstract
- A Cu(II) complex [CuCl(C19H20N40)]ClO4 1 containing hydroxymethyl substituted TPA (TPA = tris(2-pyridylmethyl)amine) was prepared. It crystallizes in monoclinic, space group P2(1)/c with a = 11.7628(2), b = 13.0083(3), c = 15.11280(10) Angstrom, beta = 108.724(2)degrees, V = 2190.09(7) Angstrom(3), M-r = 518.83, Z = 4, T = 293 (2) K, D-c = 1.574 g/cm(3), mu = 1.280 mm(-1), F(000) = 1060 and S = 1.085. The final R = 0.0543 and wR = 0.1433 for 2693 observed reflections with I >2sigma(I). The penta-coordinated copper (H) complex. assumes an approximate square pyramidal geometry. Cyclic voltammetry measurement of the complex showed a quasi-reversible Cu-II/Cu-I redox couple with E-1/2 -0.467 v and DeltaE = 68 mv.
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5. |
- Gayou, O, et al.
(author)
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Measurement of G(Ep)/G(Mp) in (e)over-right-arrowp -> e(p)over-right-arrow to Q(2)=5.6 GeV2
- 2002
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In: Physical Review Letters. - 1079-7114. ; 88:9
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Journal article (peer-reviewed)abstract
- The ratio of the electric and magnetic form factors of the proton G(Ep)/G(Mp), which is an image of its charge and magnetization distributions, was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the recoil polarization technique. The ratio of the form factors is directly proportional to the ratio of the transverse to longitudinal components of the polarization of the recoil proton in the elastic (e) over right arrowp --> e (p) over right arrow reaction. The new data presented span the range 3.5 < Q(2) < 5.6 GeV2 and are well described by a linear Q(2) fit. Also, the ratio rootQ(2) F-2p/F-1p reaches a constant value above Q(2) = 2 GeV2.
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6. |
- Schulte, EC, et al.
(author)
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High energy angular distribution measurements of the exclusive deuteron photodisintegration reaction
- 2002
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In: Physical Review C (Nuclear Physics). - : American Physical Society. - 0556-2813 .- 1089-490X. ; 66:4
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Journal article (peer-reviewed)abstract
- The first complete measurements of the angular distributions of the two-body deuteron photodisintegration differential cross section at photon energies above 1.6 GeV were performed at the Thomas Jefferson National Accelerator Facility. The results show a persistent forward-backward asymmetry up to E-gamma=2.4 GeV, the highest-energy measured in this experiment. The Hard Rescattering and the Quark-Gluon string models are in fair agreement with the results.
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7. |
- Wijesooriya, K, et al.
(author)
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Polarization measurements in neutral pion photoproduction
- 2002
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:3
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Journal article (peer-reviewed)abstract
- We present measurements of the recoil proton polarization for the H-1((γ) over right arrow,(p) over right arrow)pi(0) reaction for theta(c.m.)(pi) = 60degrees-135degrees and for photon energies up to 4.1 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. Various theoretical models are compared with the results. No evidence for hadron helicity conservation is observed. Models that employ factorization are not favored. It appears from the strong angular dependence of the induced polarization at photon energies of 2.5 and 3.1 GeV that a relatively high spin resonance or background amplitude might exist in this energy region.
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10. |
- Cheung, Herman H., et al.
(author)
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Monitor – Biology
- 2004
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In: Drug Discovery Today. - 1878-5832. ; 9:6, s. 287-290
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Journal article (peer-reviewed)abstract
- The hottest developments in the fields of cancer research, neuroscience, genomics and proteomics, anti-virals and more, with a pick of the key research papers in these areas.
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11. |
- Dutta, D, et al.
(author)
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Nuclear transparency with the gamma n ->pi(-)p process in He-4
- 2003
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 68:2: 021001
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Journal article (peer-reviewed)abstract
- We have measured the nuclear transparency of the fundamental process gamman-->pi(-)p in He-4. These measurements were performed at Jefferson Lab in the photon energy range of 1.6-4.5 GeV and at theta(cm)(pi)=70degrees and 90degrees. These measurements are the first of their kind in the study of nuclear transparency in photoreactions. They also provide a benchmark test of Glauber calculations based on traditional models of nuclear physics. The transparency results suggest deviations from the traditional nuclear physics picture. The momentum transfer dependence of the measured nuclear transparency is consistent with Glauber calculations that include the quantum chromodynamics phenomenon of color transparency.
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12. |
- Lindberg, Marie K, 1975, et al.
(author)
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Estrogen receptor specificity for the effects of estrogen in ovariectomized mice.
- 2002
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In: The Journal of endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 174:2, s. 167-78
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Journal article (peer-reviewed)abstract
- Estrogen exerts a variety of important physiological effects, which have been suggested to be mediated via the two known estrogen receptors (ERs), alpha and beta. Three-month-old ovariectomized mice, lacking one or both of the two estrogen receptors, were given estrogen subcutaneously (2.3 micro g/mouse per day) and the effects on different estrogen-responsive parameters, including skeletal effects, were studied. We found that estrogen increased the cortical bone dimensions in both wild-type (WT) and double ER knockout (DERKO) mice. DNA microarray analysis was performed to characterize this effect on cortical bone and it identified four genes that were regulated by estrogen in both WT and DERKO mice. The effect of estrogen on cortical bone in DERKO mice might either be due to remaining ERalpha activity or represent an ERalpha/ERbeta-independent effect. Other effects of estrogen, such as increased trabecular bone mineral density, thymic atrophy, fat reduction and increased uterine weight, were mainly ERalpha mediated.
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13. |
- Mason, M.G., et al.
(author)
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Interfacial chemistry of Alq3 and LiF with reactive metals
- 2001
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 89:5, s. 2756-2765
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Journal article (peer-reviewed)abstract
- The electronic structure and chemistry of interfaces between tris-(8-hydroxyquinoline) aluminum (Alq3) and representative group IA and IIA metals, Al, and Al/LiF have been studied by x-ray and ultraviolet photoelectron spectroscopies. Quantum-chemical calculations at the density functional theory level predict that the Alq3 radical anion is formed upon reaction with the alkali metals. In this case, up to three metal atoms can react with a given Alq3 molecule to form the trivalent anion. The anion formation results in a splitting of the N 1 s core level and formation of a new feature in the previously forbidden energy gap. Virtually identical spectra are observed in the Al/LiF/Alq3 system, leading to the conclusion that the radical anion is also formed when all three of these constituents are present. This is support by a simple thermodynamic model based on bulk heats of formation. In the absence of LiF or similar material, the reaction of Al with Alq3 appears to be destructive, with the deposited Al reacting directly with the quinolate oxygen. We proposed that in those circumstances where the radical anion is formed, it and not the cathode metal are responsible for the electron injection properties. This is borne out by producing excellent injecting contacts when Ag and Au are used as the metallic component of the cathode structure. © 2001 American Institute of Physics.
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14. |
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15. |
- Sun, S. G., et al.
(author)
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Studies on a series of rhenium(I) bipyridyl photosensitive dyes
- 2004
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In: Youji huaxue. - 0253-2786. ; 24:8, s. 953-956
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Journal article (peer-reviewed)abstract
- A series of rhemium(I) 2,2'-bipyridyl complexes [fac-(4,4'-di-COOEt-bpy)Re(CO)(3)(Xpy)PF6] (bpy = 2, 2'-bipyridine; py = pyridine; X = 3-methyl, 3-hydroxy, 3-amino, H) were synthesized. Their electrochemical properties, ground state electronic spectra and emission spectra were studied in acetonitrile. As the X group became more electron donating from H to 3-methyl, 3-hydroxy or 3-amino, the Re(II/I) oxidation potentials declined, the MLCT absorption maximum of the complex was changed little, the emission maximum blue-shifted, and the emission intensity and the fluorescence lifetime were decreased.
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16. |
- Sun, S. G., et al.
(author)
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Synthesis of a series of rhenium(I) bipyridyl complexes as photosensitive dyes
- 2004
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In: Gaodeng xuéxiào huàxué xuébào. - 0251-0790. ; 25:5, s. 820-822
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Journal article (peer-reviewed)abstract
- In order to study the effects of the substituted groups on the properties of the complexes, a series of rhenium ( I ) 2, 2'-bipyridyl complexes [fac- (4, 4'-di-COOEt-bpy) Re (CO)(3) (X-pyridine) PF6], where bpy is 2,2'-bipyridine and X is 4-methyl, 3-hydroxy, 4-hydroxy, 4-amino, or H, were synthesized with a yield more than 90%, and characterized by H-1 NMR, C-13 NMR, 2D-NMR (H-1-H-1 COSY, HMBC, HSQC), ESI-MS and HRMS. The delta(H) values on the X-pyridine ring were shifted to up-field in H-1 NMR and the MLCT absorbance maxima were red-shifted as the X groups became more electron-donating from H to 4-methyl, 4-hydroxy or 4-amino. The ESI-MS and FIRMS showed the mono-charged peaks and their isotopic peaks of the complexes. The absorption maximum of id(X=4-amino) is 20 nm longer than that of 1e(X=H). It might be used to broaden the absorption range of solar cells.
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17. |
- Sun, S. G., et al.
(author)
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Synthesis of rhenium(I) bipyridyl and ruthenium(II) tris-bipyridyl photosensitive dyes used for solar cells
- 2004
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In: Gaodeng xuéxiào huàxué xuébào. - 0251-0790. ; 25:1, s. 67-70
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Journal article (peer-reviewed)abstract
- There has been a growing effort to convert solar energy into electricity in recent years. In order to get a stable solar cell system and acquire a high incident photon-to-current conversion efficiency(IPCE), two novel rhenium(I) bipyridyl and ruthenium(II) tris-bipyridyl photosensitive dyes were synthesized, the ethoxycarbonyl group in the dyes could be employed for covalently linking to the surface of the nanostructured TiO2. Their structures, photophysical and electrochemical properties were studied. The UV-Vis absorption maxima were 382 and 476 nm; emission maxima were 622 and 672 nm, respectively. The Re(I/II) oxidation potential is significantly positive than that of Ru(II/III) which provides a larger driving force for electron transfer. The results show that they both have proper redox potentials, enough stability and are suitable for being used as photosensitizers of solar cells.
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18. |
- Zhu, LY, et al.
(author)
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Cross-section measurement of charged-pion photoproduction from hydrogen and deuterium
- 2003
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In: Physical Review Letters. - 1079-7114. ; 91:2: 022003
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Journal article (peer-reviewed)abstract
- We have measured the differential cross section for the gamman-->pi(-)p and gammap-->pi(+)n reactions at theta(c.m.)=90degrees in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at E(gamma)greater than or similar to3.3 GeV exhibit a global scaling behavior for both pi(-) and pi(+) photoproduction, consistent with the constituent counting rule and the existing pi(+) photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi(-) to pi(+) photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams.
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