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- Adloff, C, et al.
(författare)
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Measurement of D*(+/-) meson production and F-2(c) in deep-inelastic scattering at HERA
- 2002
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 528:3-4, s. 199-214
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Tidskriftsartikel (refereegranskat)abstract
- The inclusive production of D*+/-(2010) mesons in deep-inelastic scattering is studied with the HI detector at HERA. In the kinematic region 1 < Q(2) < 100 GeV2 and 0.05 < y < 0.7 an e(+) p cross section for inclusive D*+/- meson production of 8.50 +/- 0.42(stat.)(-100)(+1.21)(syst.) nb is measured in the visible range p(tD*) > 1.5 GeV and eta(D*) < 1.5. Single and double differential inclusive D*+/- meson cross sections are compared to perturbative QCD calculations in two different evolution schemes, The charm contribution to the proton structure, F-c(2)(x, Q(2)), is determined by extrapolating the visible charm cross section to the full phase space. This contribution is found to rise from about 10% at Q(2) = 1.5 GeV2 to more than 25% at Q(2) = 60 GeV2 corresponding to x values ranging from 5 x 10(-5) to 3 x 10(-3). (C) 2002 Elsevier Science B.V. All rights reserved.
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| 2. |
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| 3. |
- Moros, M, et al.
(författare)
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Quartz content and the quartz-to-plagioclase ratio determined by X-ray diffraction: a proxy for ice rafting in the northern North Atlantic?
- 2004
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Ingår i: Earth and Planetary Science Letters. - 1385-013X. ; 218:3-4, s. 389-401
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Tidskriftsartikel (refereegranskat)abstract
- Many paleoceanographic reconstructions of the glacial North Atlantic include estimates of iceberg discharge, which are based on the variable abundance of ice-rafted detritus (IRD) in deep-sea sediments. IRD abundance is most often determined by the mechanical separation and painstaking counting of terrigenous particles larger than a specified threshold grain size, typically 150 mum. Here we present a new proxy for IRD based on X-ray diffraction (XRD) analysis of bulk sediments. This approach complements results obtained from standard techniques while offering several distinct advantages. In addition to the rapid production of objective data, XRD measurements on bulk sediments are sensitive to a broader and more characteristic grain size range than counts of individual coarse lithic fragments. The technique is demonstrated in a study of 12 sediment cores from the North Atlantic. Bulk quartz content and the quartz-to-plagioclase ratio exhibit peak-to-peak correspondence to manual counting results, which verifies the identification of large IRD influxes. The XRD data also reveal variations between the manually identified peaks, suggesting increased sensitivity to low-level, distal, or sea-ice sources of IRD. A saw-tooth pattern emerges in many IRD events, which supports a link between ice rafting and atmospheric temperature changes over Greenland, and providing further evidence of the influence of climate on iceberg discharges. (C) 2003 Elsevier B.V. All rights reserved.
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| 6. |
- Oku, T, et al.
(författare)
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Modulated structure of Ag2SnO3 studied by high-resolution electron microscopy
- 2000
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Ingår i: Acta Crystallographica. Section B: Structural Science. - 0108-7681. ; 56:3, s. 363-368
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Tidskriftsartikel (refereegranskat)abstract
- The modulated structure of Ag2SnO3, disilver tin trioxide, was investigated by high-resolution electron microscopy and electron diffraction along four different directions. Electron diffraction showed an incommensurate one-dimensional modulated structure with a modulation wavevector of 1/6.4a*. High-resolution images showed a large number of superstructure domains with the size range 10-100 nm and orientations related by hexagonal rotation. The modulation was determined to be displacements along the c axis of the Ag atoms both in octahedral and linear coordination. An approximate structure model with a commensurate sixfold superstructure, with an orthorhombic cell (P2(1)2(1)2(1), a = 2.922, b = 1.267, c = 0.562 nm), is proposed. Calculated images and electron diffraction patterns, based on this model, agree well with experimental observations.
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| 8. |
- Silins, Ilvars, et al.
(författare)
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A population-based study of cervical carcinoma and HPV infection in Latvia.
- 2004
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Ingår i: Gynecologic Oncology. - : Academic Press. - 0090-8258 .- 1095-6859. ; 93:2, s. 484-492
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: We wished to quantify the population-based importance of cervical carcinoma risk factors in Latvia.METHODS: Totally, 223 of 224 eligible cases of incident invasive cervical carcinoma were enrolled during July 1998-February 2001 in Latvia. An age-matched sample of 300 healthy control women was selected from the Latvian population registry and 239 of these women (79%) were enrolled. A demographic and life-style questionnaire was completed, cervical brush samples were analyzed for human papillomavirus (HPV) DNA by PCR and serum samples for HPV antibodies.RESULTS: Risk factors for cervical cancer in multivariate analysis were HPV type 16 or 18 DNA positivity (OR = 32.4; CI 95% 16.5-63.6) and living in the capital (OR = 2.4; CI 95% 1.2-4.7). Oral contraceptive use was not a risk factor (OR = 0.4; CI 95% 0.2-1.1). A strong protective effect was found for having had more than three Pap smears in the last 5 years (OR = 0.07 CI 95% 0.03-0.19).CONCLUSIONS: Inadequate population coverage of Pap smears, in spite of excessive smear usage, caused 28.4% of cervical cancers in age groups eligible for screening. HPV type 16 infection was the most important risk factor for cervical cancer in Latvia, with a population-attributable risk percent for all ages of 58.5%.
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