| 1. |
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| 2. |
- Abdo, A. A., et al.
(författare)
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Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 323:5922, s. 1688-1693
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gamma-ray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.
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| 3. |
- Abdo, A. A., et al.
(författare)
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Fermi/LAT observations of LS 5039
- 2009
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Ingår i: Astrophysical Journal Letters. - 0571-7248 .- 2041-8205. ; 706:1, s. L56-L61
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Tidskriftsartikel (refereegranskat)abstract
- The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 ± 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 ± 0.5(stat) ± 1.8(syst) ×10–7 photon cm–2 s–1, with a cutoff at 2.1 ± 0.3(stat) ± 1.1(syst) GeV and photon index Γ = 1.9 ± 0.1(stat) ± 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.
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| 4. |
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| 5. |
- Abe, O, et al.
(författare)
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Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials
- 2005
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Ingår i: The Lancet. - 1474-547X. ; 365:9472, s. 1687-1717
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Tidskriftsartikel (refereegranskat)abstract
- Background Quinquennial overviews (1985-2000) of the randomised trials in early breast cancer have assessed the 5-year and 10-year effects of various systemic adjuvant therapies on breast cancer recurrence and survival. Here, we report the 10-year and 15-year effects. Methods Collaborative meta-analyses were undertaken of 194 unconfounded randomised trials of adjuvant chemotherapy or hormonal therapy that began by 1995. Many trials involved CMF (cyclophosphamide, methotrexate, fluorouracil), anthracycline-based combinations such as FAC (fluorouracil, doxombicin, cyclophosphamide) or FEC (fluorouracil, epirubicin, cyclophosphamide), tamoxifen, or ovarian suppression: none involved taxanes, trastuzumab, raloxifene, or modem aromatase inhibitors. Findings Allocation to about 6 months of anthracycline-based polychemotherapy (eg, with FAC or FEC) reduces the annual breast cancer death rate by about 38% (SE 5) for women younger than 50 years of age when diagnosed and by about 20% (SE 4) for those of age 50-69 years when diagnosed, largely irrespective of the use of tamoxifen and of oestrogen receptor (ER) status, nodal status, or other tumour characteristics. Such regimens are significantly (2p=0 . 0001 for recurrence, 2p<0 . 00001 for breast cancer mortality) more effective than CMF chemotherapy. Few women of age 70 years or older entered these chemotherapy trials. For ER-positive disease only, allocation to about 5 years of adjuvant tamoxifen reduces the annual breast cancer death rate by 31% (SE 3), largely irrespective of the use of chemotherapy and of age (<50, 50-69, &GE; 70 years), progesterone receptor status, or other tumour characteristics. 5 years is significantly (2p<0 . 00001 for recurrence, 2p=0 . 01 for breast cancer mortality) more effective than just 1-2 years of tamoxifen. For ER-positive tumours, the annual breast cancer mortality rates are similar during years 0-4 and 5-14, as are the proportional reductions in them by 5 years of tamoxifen, so the cumulative reduction in mortality is more than twice as big at 15 years as at 5 years after diagnosis. These results combine six meta-analyses: anthracycline-based versus no chemotherapy (8000 women); CMF-based versus no chemotherapy (14 000); anthracycline-based versus CMF-based chemotherapy (14 000); about 5 years of tamoxifen versus none (15 000); about 1-2 years of tamoxifen versus none (33 000); and about 5 years versus 1-2 years of tamoxifen (18 000). Finally, allocation to ovarian ablation or suppression (8000 women) also significantly reduces breast cancer mortality, but appears to do so only in the absence of other systemic treatments. For middle-aged women with ER-positive disease (the commonest type of breast cancer), the breast cancer mortality rate throughout the next 15 years would be approximately halved by 6 months of anthracycline-based chemotherapy (with a combination such as FAC or FEC) followed by 5 years of adjuvant tamoxifen. For, if mortality reductions of 38% (age <50 years) and 20% (age 50-69 years) from such chemotherapy were followed by a further reduction of 31% from tamoxifen in the risks that remain, the final mortality reductions would be 57% and 45%, respectively (and, the trial results could well have been somewhat stronger if there had been full compliance with the allocated treatments). Overall survival would be comparably improved, since these treatments have relatively small effects on mortality from the aggregate of all other causes. Interpretation Some of the widely practicable adjuvant drug treatments that were being tested in the 1980s, which substantially reduced 5-year recurrence rates (but had somewhat less effect on 5-year mortality rates), also substantially reduce 15-year mortality rates. Further improvements in long-term survival could well be available from newer drugs, or better use of older drugs.
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| 6. |
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| 7. |
- Abdo, A. A., et al.
(författare)
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Fermi LAT Observations of LS I +61°303 : First Detection of an Orbital Modulation in GeV Gamma Rays
- 2009
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Ingår i: Astrophysical Journal Letters. - 2041-8205. ; 701:2, s. L123-L128
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Tidskriftsartikel (refereegranskat)abstract
- This Letter presents the first results from the observations of LS I +61°303 using Large Area Telescope data from the Fermi Gamma-Ray Space Telescope between 2008 August and 2009 March. Our results indicate variability that is consistent with the binary period, with the emission being modulated at 26.6 ± 0.5 days. This constitutes the first detection of orbital periodicity in high-energy gamma rays (20 MeV-100 GeV, HE). The light curve is characterized by a broad peak after periastron, as well as a smaller peak just before apastron. The spectrum is best represented by a power law with an exponential cutoff, yielding an overall flux above 100 MeV of 0.82 ± 0.03(stat) ± 0.07(syst) 10-6 ph cm-2 s-1, with a cutoff at 6.3 ± 1.1(stat) ± 0.4(syst) GeV and photon index Γ = 2.21 ± 0.04(stat) ± 0.06(syst). There is no significant spectral change with orbital phase. The phase of maximum emission, close to periastron, hints at inverse Compton scattering as the main radiation mechanism. However, previous very high-energy gamma ray (>100 GeV, VHE) observations by MAGIC and VERITAS show peak emission close to apastron. This and the energy cutoff seen with Fermi suggest that the link between HE and VHE gamma rays is nontrivial.
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| 8. |
- Hibbett, D. S., et al.
(författare)
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A higher-level phylogenetic classification of the Fungi
- 2007
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Ingår i: Mycological Research. - : Elsevier BV. - 0953-7562 .- 1469-8102. ; 111, s. 509-547
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive phylogenetic classification of the kingdom Fungi is proposed, with reference to recent molecular phylogenetic analyses, and with input from diverse members of the fungal taxonomic community. The classification includes 195 taxa, down to the level of order, of which 16 are described or validated here: Dikarya subkingdom nov.; Chytridiomycota, Neocallimastigomycota phyla nov.; Monoblepharidomycetes, Neocallimastigomycetes class. nov.; Eurotiomycetidae, Lecarioromycetidae, Mycocaliciomycetidae subclass. nov.; Acarosporales, Corticiales, Baeomycetales, Candelariales, Gloeophyllales, Melanosporales, Trechisporales, Umbilicariales ords. nov. The clade containing Ascomycota and Basidiomycota is classified as subkingdom Dikarya, reflecting the putative synapomorphy of dikaryotic hyphae. The most dramatic shifts in the classification relative to previous works concern the groups that have traditionally been included in the Chytridiomycota and Zygomycota. The Chytridiomycota is retained in a restricted sense, with Blastocladiomycota and Neocallimastigomycota representing segregate phyla of flagellated Fungi. Taxa traditionally placed in Zygomycota are distributed among Glomeromycota and several subphyla incertae sedis, including Mucoromycotina, Entomophthoromycotina, Kickxellomycotina, and Zoopagomycotiria. Microsporidia are included in the Fungi, but no further subdivision of the group is proposed. Several genera of 'basal' Fungi of uncertain position are not placed in any higher taxa, including Basidiobolus, Caulochytrium, Olpidium, and Rozella. (c) 2007 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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| 9. |
- Genkinger, J M, et al.
(författare)
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A pooled analysis of 12 cohort studies of dietary fat, cholesterol and egg intake and ovarian cancer
- 2006
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Ingår i: Cancer Causes and Control. - Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA USA. Harvard Univ, Sch Med, Boston, MA USA. Harvard Univ, Sch Publ Hlth, Harvard Ctr Canc Prevent, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. Univ Minnesota, Sch Publ Hlth, Div Epidemiol, Minneapolis, MN 55455 USA. Loma Linda Univ, Sch Med, Ctr Hlth Res, Loma Linda, CA USA. Brigham & Womens Hosp, Div Prevent Med, Boston, MA 02115 USA. SUNY Buffalo, Dept Social & Prevent Med, Buffalo, NY 14260 USA. : SPRINGER. - 0957-5243 .- 1573-7225. ; 17:3, s. 273-285
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Tidskriftsartikel (refereegranskat)abstract
- Fat and cholesterol are theorized to promote ovarian carcinogenesis by increasing circulating estrogen levels. Although case-control studies have reported positive associations between total and saturated fat intake and ovarian cancer risk, two cohort studies have observed null associations. Dietary cholesterol and eggs have been positively associated with ovarian cancer risk. A pooled analysis was conducted on 12 cohort studies. Among 523,217 women, 2,132 incident epithelial ovarian cancer cases were identified. Study-specific relative risks (RR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards models, and then pooled using a random effects model. Total fat intake was not associated with ovarian cancer risk (pooled multivariate RR = 1.08, 95% CI 0.86-1.34 comparing >= 45 to 30-< 35% of calories). No association was observed for monounsaturated, polyunsaturated, trans-unsaturated, animal and vegetable fat, cholesterol and egg intakes with ovarian cancer risk. A weakly positive, but non-linear association, was observed for saturated fat intake (pooled multivariate RR = 1.29, 95% CI: 1.01-1.66 comparing highest versus lowest decile). Results for histologic subtypes were similar. Overall, fat, cholesterol and egg intakes were not associated with ovarian cancer risk. The positive association for saturated fat intake at very high intakes merits further investigation.
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| 10. |
- Maierbeck, P., et al.
(författare)
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Probing the single particle structure around Ca-54 with one-neutron knock-out
- 2008
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Ingår i: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1012, s. 89-93
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Konferensbidrag (refereegranskat)abstract
- The nuclei Ca-47 and Ti-55 were populated in one-neutron knock-out reactions at relativistic energies. Momentum distributions of the residual nuclei as well as gamma-ray spectra were measured at the GSI fragment separator (FRS). Preliminary results of the ongoing analysis including cross sections and spin/parity assignments are presented.
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| 11. |
- Genkinger, J M, et al.
(författare)
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Alcohol intake and ovarian cancer risk : a pooled analysis of 10 cohort studies
- 2006
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Ingår i: British Journal of Cancer. - Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. Univ Minnesota, Sch Publ Hlth, Div Epidemiol, Minneapolis, MN USA. Brigham & Womens Hosp, Dept Med, Div Prevent Med, Boston, MA 02115 USA. Harvard Univ, Sch Med, Boston, MA 02115 USA. SUNY Buffalo, Dept Social & Prevent Med, Buffalo, NY USA. TNO, Dept Food & Chem Risk Anal, Zeist, Netherlands. Natl Inst Environm Med, Karolinska Inst, Div Nutr Epidemiol, Stockholm, Sweden. NCI, Div Canc Epidemiol & Genet, NIH, DHHS, Bethesda, MD 20892 USA. Amer Canc Soc, Atlanta, GA 30329 USA. Univ Toronto, Dept Publ Hlth Sci, Fac Med, Toronto, ON, Canada. Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY 10467 USA. Maastricht Univ, NUTRIM, Dept Epidemiol, Maastricht, Netherlands. : NATURE PUBLISHING GROUP. - 0007-0920 .- 1532-1827. ; 94:5, s. 757-762
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Tidskriftsartikel (refereegranskat)abstract
- Alcohol has been hypothesized to promote ovarian carcinogenesis by its potential to increase circulating levels of estrogen and other hormones; through its oxidation byproduct, acetaldehyde, which may act as a cocarcinogen; and by depletion of folate and other nutrients. Case-control and cohort studies have reported conflicting results relating alcohol intake to ovarian cancer risk. We conducted a pooled analysis of the primary data from ten prospective cohort studies. The analysis included 529 638 women among whom 2001 incident epithelial ovarian cases were documented. After study-specific relative risks ( RR) and 95% confidence intervals ( CI) were calculated by Cox proportional hazards models, and then were pooled using a random effects model; no associations were observed for intakes of total alcohol ( pooled multivariate RR 1.12, 95% CI 0.86-1.44 comparing >= 30 to 0 g day(-1) of alcohol) or alcohol from wine, beer or spirits and ovarian cancer risk. The association with alcohol consumption was not modified by oral contraceptive use, hormone replacement therapy, parity, menopausal status, folate intake, body mass index, or smoking. Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings. This pooled analysis does not support an association between moderate alcohol intake and ovarian cancer risk.
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| 12. |
- Genkinger, J M, et al.
(författare)
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Dairy products and ovarian cancer : A pooled analysis of 12 cohort studies
- 2006
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. Brigham & Womens Hosp, Channing Lab, Boston, MA 02115 USA. Brigham & Womens Hosp, Dept Med, Boston, MA 02115 USA. Brigham & Womens Hosp, Div Prevent Med, Boston, MA 02115 USA. Harvard Univ, Sch Med, Boston, MA USA. Univ Minnesota, Sch Publ Hlth, Div Epidemiol, Minneapolis, MN 55455 USA. NYU, Dept Environm Med, Div Epidemiol, New York, NY 10016 USA. Loma Linda Univ, Sch Med, Ctr Hlth Res, Loma Linda, CA USA. SUNY Buffalo, Dept Social & Prevent Med, Buffalo, NY 14260 USA. Netherlands Org Appl Sci Res Qual Life, Dept Food & Chem Risk Anal, Zeist, Netherlands. Univ Oslo, Dept Nutr, Oslo, Norway. NCI, Div Canc Epidemiol & Genet, NIH, Dept Hlth & Human Serv, Bethesda, MD 20892 USA. Natl Inst Environm Med, Div Nutr Epidemiol, Karolinska Inst, Stockholm, Sweden. Amer Canc Soc, Atlanta, GA 30329 USA. Univ Toronto, Fac Med, Dept Publ Hlth Sci, Toronto, ON, Canada. Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY 10467 USA. Maastricht Univ, Dept Epidemiol, Nutr & Toxicol Res Inst, Maastricht, Netherlands. : AMER ASSOC CANCER RESEARCH. - 1055-9965 .- 1538-7755. ; 15:2, s. 364-372
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dairy foods and their constituents (lactose and calcium) have been hypothesized to promote ovarian carcinogenesis. Although case-control studies have reported conflicting results for dairy foods and lactose, several cohort studies have shown positive associations between skim milk, lactose, and ovarian cancer. Methods: A pooled analysis of the primary data from 12 prospective cohort studies was conducted. The study population consisted of 553,217 women among whom 2,132 epithelial ovarian cases were identified. Study-specific relative risks and 95% confidence intervals were calculated by Cox proportional hazards models and then pooled by a random-effects model. Results: No statistically significant associations were observed between intakes of milk, cheese, yogurt, ice cream, and dietary and total calcium intake and risk of ovarian cancer. Higher lactose intakes comparing >= 30 versus < 10 g/d were associated with a statistically significant higher risk of ovarian cancer, although the trend was not statistically significant (pooled multivariate relative risk, 1.19; 95% confidence interval, 1.01-1.40; P-trend = 0.19). Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings. Discussion: Overall, no associations were observed for intakes of specific dairy foods or calcium and ovarian cancer risk. A modest elevation in the risk of ovarian cancer was seen for lactose intake at the level that was equivalent to three or more servings of milk per day. Because a new dietary guideline recommends two to three servings of dairy products per day, the relation between dairy product consumption and ovarian cancer risk at these consumption levels deserves further examination.
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| 13. |
- Greiner, J., et al.
(författare)
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Gamma-ray burst investigation via polarimetry and spectroscopy (GRIPS)
- 2009
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 23:1, s. 91-120
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Tidskriftsartikel (refereegranskat)abstract
- The primary scientific goal of the GRIPS mission is to revolutionize our understanding of the early universe using gamma-ray bursts. We propose a new generation gamma-ray observatory capable of unprecedented spectroscopy over a wide range of gamma-ray energies (200 keV-50 MeV) and of polarimetry (200-1000 keV). The gamma-ray sensitivity to nuclear absorption features enables the measurement of column densities as high as 10(28)cm (-aEuro parts per thousand 2). Secondary goals achievable by this mission include direct measurements of all types of supernova interiors through gamma-rays from radioactive decays, nuclear astrophysics with massive stars and novae, and studies of particle acceleration near compact stars, interstellar shocks, and clusters of galaxies.
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| 14. |
- Koushik, A, et al.
(författare)
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Fruits and vegetables and ovarian cancer risk in a pooled analysis of 12 cohort studies
- 2005
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA USA. Brigham & Womens Hosp, Dept Med, Div Prevent Med, Boston, MA USA. Harvard Univ, Sch Med, Boston, MA USA. Harvard Univ, Ctr Canc Prevent, Boston, MA 02115 USA. Univ Minnesota, Sch Publ Hlth, Div Epidemiol, Minneapolis, MN 55455 USA. NYU, Sch Med, Div Epidemiol, Dept Environm Med, New York, NY USA. NYU, Sch Med, Div Biostat, Dept Environm Med, New York, NY USA. Loma Linda Univ, Sch Med, Ctr Hlth Res, Loma Linda, CA USA. Maastricht Univ, Dept Epidemiol, Maastricht, Netherlands. Mayo Clin & Mayo Fdn, Dept Hlth Sci Res, Coll Med, Rochester, MN 55905 USA. SUNY Buffalo, Dept Social & Prevent Med, Buffalo, NY 14260 USA. TNO, Nutr & Food Res Inst, Dept Epidemiol, Zeist, Netherlands. Karolinska Inst, Div Nutr Epidemiol, Natl Inst Environm Med, Stockholm, Sweden. NCI, Div Canc Epidemiol & Genet, NIH, Bethesda, MD 20892 USA. Amer Canc Soc, Atlanta, GA 30329 USA. Univ Toronto, Fac Med, Dept Publ Hlth Sci, Toronto, ON, Canada. Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY 10467 USA. : AMER ASSOC CANCER RESEARCH. - 1055-9965 .- 1538-7755. ; 14:9, s. 2160-2167
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Tidskriftsartikel (refereegranskat)abstract
- Because fruits and vegetables are rich in bioactive compounds with potential cancer-preventive actions, increased consumption may reduce the risk of ovarian cancer. Evidence on the association between fruit and vegetable intake and ovarian cancer risk has not been consistent. We analyzed and pooled the primary data from 12 prospective studies in North America and Europe. Fruit and vegetable intake was measured at baseline in each study using a validated food frequency questionnaire. To summarize the association between fruit and vegetable intake and ovarian cancer, study-specific relative risks (RR) were estimated using the Cox proportional hazards model, and then combined using a random-effects model. Among 560,441 women, 2,130 cases of invasive epithelial ovarian cancer occurred during a maximum follow-up of 7 to 22 years across studies. Total fruit intake was not associated with ovarian cancer risk-the pooled multivariate RR for the highest versus the lowest quartile of intake was 1.06 [95% confidence interval (95% CI), 0.92-1.21; P value, test for trend = 0.73; P value, test for between-studies heterogeneity = 0.741. Similarly, results for total vegetable intake indicated no significant association (pooled multivariate RR, 0.90; 95% Cl, 0.78-1.04, for the highest versus the lowest quartile; P value, test for trend = 0.06; P value, test for between-studies heterogeneity = 0.31). Intakes of botanically defined fruit and vegetable groups and individual fruits and vegetables were also not associated with ovarian cancer risk. Associations for total fruits and vegetables were similar for different histologic types. These results suggest that fruit and vegetable consumption in adulthood has no important association with the risk of ovarian cancer.
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| 15. |
- Lindehammer, Sabina, et al.
(författare)
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Temporal trends of HLA genotype frequencies of type 1 diabetes patients in Sweden from 1986 to 2005 suggest altered risk
- 2008
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Ingår i: Acta Diabetologica. - : Springer Science and Business Media LLC. - 0940-5429 .- 1432-5233. ; 45:4, s. 231-5
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the frequency of human leukocyte antigen (HLA) genotypes in 1-18-year-old patients with type 1 diabetes newly diagnosed in 1986-1987 (n = 430), 1996-2000 (n = 342) and in 2003-2005 (n = 171). We tested the hypothesis that the HLA DQ genotype distribution changes over time. Swedish type 1 diabetes patients and controls were typed for HLA using polymerase chain reaction amplification and allele specific probes for DQ A1* and B1* alleles. The most common type 1 diabetes HLA DQA1*-B1*genotype 0501-0201/0301-0302 was 36% (153/430) in 1986-1987 and 37% (127/342) in 1996-2000, but decreased to 19% (33/171) in 2003-2005 (P \ 0.0001). The 0501-0201/0501-0201 genotype increased from 1% in 1986-1987 to 7% in 1996-2000 (P = 0.0047) and to 5% in 2003-2005 (P > 0.05). This study in 1-18-year-old Swedish type 1 diabetes patients supports the notion that there is a temporal change in HLA risk.
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| 16. |
- Maierbeck, P., et al.
(författare)
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Structure of 55Ti from relativistic one-neutron knockout
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 675:1, s. 22-27
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.
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| 17. |
- Gaffney, K J, et al.
(författare)
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Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb
- 2005
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 95:12
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Tidskriftsartikel (refereegranskat)abstract
- The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.
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| 18. |
- Lopes, S M C D, et al.
(författare)
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Altered primordial germ cell migration in the absence of transforming growth factor beta signaling via ALK5
- 2005
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Ingår i: Developmental Biology. - : Elsevier BV. - 1095-564X .- 0012-1606. ; 284:1, s. 194-203
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor beta (TGF beta) inhibits proliferation and promotes the migration of primordial germ cells (PGCs) towards explants of gonadal ridges in vitro. However, its effects in vivo are still unclear. Here, we analyzed the behavior of PGCs in embryos lacking TGF beta signaling via the type I receptor ALK5. TGF beta in vivo was neither a chemoattractant for PGCs, nor did it affect their proliferation during migration towards the gonadal ridges up to embryonic day (E) 10. Unexpectedly, the absence of TGF beta signaling in fact resulted in significant facilitation of PGC migration out of the hindgut, due to the reduced deposition of collagen type I surrounding the gut of Alk5-deficient mutant embryos. Migratory PGCs adhere strongly to collagen; therefore, reduced collagen type I along the gut may result in reduced adhesion, facilitating migration into the dorsal mesenterium and gonadal ridges. Our results provide new evidence for the role of TGF beta signaling in migration of PGCs in vivo distinct from that described previously.
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| 19. |
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| 20. |
- Ruzzante, D. E., et al.
(författare)
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Biocomplexity in a highly migratory pelagic marine fish, Atlantic herring
- 2006
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Ingår i: Proceedings of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 273:1593, s. 1459-1464
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Tidskriftsartikel (refereegranskat)abstract
- The existence of biologically differentiated populations has been credited with a major role in conferring sustainability and in buffering overall productivity of anadromous fish population complexes where evidence for spatial structure is uncontroversial. Here, we describe evidence of correlated genetic and life history (spawning season linked to spawning location) differentiation in an abundant and highly migratory pelagic fish, Atlantic herring, Clupea harengus, in the North Sea (NS) and adjacent areas. The existence of genetically and phenotypically diverse stocks in this region despite intense seasonal mixing strongly implicates natal homing in this species. Based on information from genetic markers and otolith morphology, we estimate the proportional contribution by NS, Skagerrak (SKG) and Kattegat and western Baltic (WBS) fish to mixed aggregations targeted by the NS fishery. We use these estimates to identify spatial and temporal differences in life history (migratory behaviour) and habitat use among genetically differentiated migratory populations that mix seasonally. Our study suggests the existence of more complex patterns of intraspecific diversity than was previously recognized. Sustainability may be compromised if such complex patterns are reduced through generalized management (e.g. area closures) that overlooks population differences in spatial use throughout the life cycle.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Henriksson, C., et al.
(författare)
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Knowledge and attitudes toward seeking medical care for AMI-symptoms
- 2009
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Ingår i: International Journal of Cardiology. - 1874-1754. ; 147:2, s. 224-227
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Time is crucial when an acute myocardial infarction (AMI) occurs, but patients often wait before seeking medical care. AIM: To investigate and compare patients' and relatives' knowledge of AMI, attitudes toward seeking medical care, and intended behaviour if AMI-symptoms occur. METHODS: The present study was a descriptive, multicentre study. Participants were AMI-patients
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| 25. |
- Koushik, Anita, et al.
(författare)
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Fruits, vegetables, and colon cancer risk in a pooled analysis of 14 cohort studies
- 2007
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Ingår i: Journal of the National Cancer Institute. - Univ Montreal, CHUM, Ctr Rech, Dept Social & Prevent Med, Montreal, PQ H2W 1V1, Canada. Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Loma Linda Univ, Ctr Hlth Res, Loma Linda, CA 92350 USA. Maastricht Univ, Dept Epidemiol, Maastricht, Netherlands. Amer Canc Soc, Atlanta, GA 30329 USA. Harvard Univ, Sch Med, Boston, MA 02115 USA. Brigham & Womens Hosp, Dept Med, Div Prevent Med, Boston, MA 02115 USA. Brigham & Womens Hosp, Channing Lab, Boston, MA 02115 USA. Univ Buffalo State Univ New York, Dept Social & Prevent Med, Buffalo, NY 14222 USA. Roswell Pk Canc Inst, Dept Canc Prevent & Populat Sci, Buffalo, NY 14263 USA. Dana Farber Canc Inst, Dept Adult Oncol, Boston, MA USA. TNO, Dept Food & Chem Risk Anal, Zeist, Netherlands. Univ Minnesota, Sch Publ Hlth, Div Epidemiol & Community Hlth, Minneapolis, MN USA. Wayne State Univ, Sch Med, Dept Pathol, Karmanos Canc Inst, Detroit, MI 48201 USA. Natl Canc Inst, Nutr Epidemiol Unit, I-20133 Milan, Italy. Karolinska Inst, Natl Inst Environm Med, Div Nutr Epidemiol, Stockholm, Sweden. NCI, Div Canc Epidemiol & Genet, Bethesda, MD 20892 USA. Univ Toronto, Fac Med, Dept Publ Hlth Sci, Toronto, ON, Canada. Natl Publ Hlth Inst, Dept Epidemiol & Hlth Promot, Helsinki, Finland. Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY 10467 USA. AZJ, Div Epidemiol, Dept Environm Med, New York, NY USA. : OXFORD UNIV PRESS INC. - 0027-8874 .- 1460-2105. ; 99:19, s. 1471-1483
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Tidskriftsartikel (refereegranskat)abstract
- Background Fruit and vegetable intakes have been associated with a reduced risk of colon cancer; however, in more recent studies associations have been less consistent. Statistical power to examine associations by colon site has been limited in previous studies. Methods Fruit and vegetable intakes in relation to colon cancer risk were examined in the Pooling Project of Prospective Studies of Diet and Cancer. Relative risks (RRs) and 95% confidence intervals (Cis) were estimated separately in 14 studies using Cox proportional hazards model and then pooled using a randomeffects model. Intakes of total fruits and vegetables, total fruits, and total vegetables were categorized according to quintiles and absolute cutpoints. Analyses were conducted for colon cancer overall and for proximal and distal colon cancer separately. All statistical tests were two-sided. Results Among 756217 men and women followed for up to 6 to 20 years, depending on the study, 5838 were diagnosed with colon cancer. The pooled multivariable RRs (95% Cis) of colon cancer for the highest versus lowest quintiles of intake were 0.91 (0.82 to 1-01 1 P-trend =.19) for total fruits and vegetables, 0.93 (0.85 to 1.02, P-trend =.28) for total fruits, and 0.94 (0.86 to 1.02, P-trend =.17) for total vegetables. Similar results were observed when intakes were categorized by identical absolute cut points across studies (pooled multivariable FIR = 0.90, 95% CI = 0.77 to 1.05 for 800 or more versus <200 g/day of total fruits and vegetables, P-trend =.06). The age-standardized incidence rates of colon cancer for these two intake categories were 54 and 61 per 100000 person-years, respectively. When analyzed by colon site, the pooled multivariable RRs (95% Cis) comparing total fruit and vegetable intakes of 800 or more versus less than 200 g/day were 0.74 (0.57 to 0.95, P-trend =.02) for distal colon cancers and 1.02 (0.82 to 1.27, P-trend =.57) for proximal colon cancers. Similar site-specific associations were observed for total fruits and total vegetables. Conclusion Fruit and vegetable intakes were not strongly associated with colon cancer risk overall but may be associated with a lower risk of distal colon cancer.
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| 26. |
- Koushik, Anita, et al.
(författare)
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Intake of the major carotenoids and the risk of epithelial ovarian cancer in a pooled analysis of 10 cohort studies
- 2006
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Ingår i: International Journal of Cancer. - Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA. Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA 02115 USA. Harvard Univ, Sch Med, Boston, MA 02115 USA. Harvard Univ, Ctr Canc Prevent, Boston, MA 02115 USA. Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA. Univ Minnesota, Sch Publ Hlth, Div Epidemiol & Community Hlth, Minneapolis, MN USA. Brigham & Womens Hosp, Dept Med, Div Prevent Med, Boston, MA 02115 USA. SUNY Buffalo, Dept Social & Prevent Med, Buffalo, NY USA. TNO, Qual Life, Dept Food & Chem Risk Anal, NL-3700 AJ Zeist, Netherlands. Karolinska Inst, Natl Inst Environm Med, Div Nutrit Epidemiol, Stockholm, Sweden. NCI, Div Canc Epidemiol & Genet, NIH, Bethesda, MD 20892 USA. Amer Canc Soc, Epidemiol & Surveillance Res, Atlanta, GA 30329 USA. Univ Toronto, Fac Med, Dept Publ Hlth Sci, Toronto, ON, Canada. Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY 10467 USA. Maastricht Univ, NUTRIM, Dept Epidemiol, Maastricht, Netherlands. : WILEY. - 0020-7136 .- 1097-0215. ; 119:9, s. 2148-2154
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Tidskriftsartikel (refereegranskat)abstract
- Carotenoids, found in fruits and vegetables, have the potential to protect against cancer because of their properties, including their functions as precursors to vitamin A and as antioxidants. We examined the associations between intakes of alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and lycopene and the risk of invasive epithelial ovarian cancer. The primary data from 10 prospective cohort studies in North America and Europe were analyzed and then pooled. Carotenoid intakes were estimated from a validated food frequency questionnaire administered at baseline in each study. Study-specific relative risks (RR) were estimated using the Cox proportional hazards model and then combined using a random-effects model. Among 521,911 women, 2,012 cases of ovarian cancer occurred during a follow-up of 7-22 years across studies. The major carotenoids were not significantly associated with the risk of ovarian cancer. The pooled multivariate RRs (95% confidence intervals) were 1.00 (0.95-1.05) for a 600 mu g/day increase in alpha-carotene intake, 0.96 (0.93-1.03) for a 2,500 mu g/day increase in beta-carotene intake, 0.99 (0.97-1.02) for a 100 mu g/day increase in beta-cryptoxanthin intake, 0.98 (0.94-1.03) for a 2,500 mu g/day increase in lutein/zeaxanthin intake and 1.01 (0.97-1.05) for a 4,000 mu g/day increase in lycopene intake. These associations did not appreciably differ by study (p-values, tests for between-studies heterogeneity > 0.17). Also, the observed associations did not vary substantially by subgroups of the population or by histological type of ovarian cancer. These results suggest that consumption of the major carotenoids during adulthood does not play a major role in the incidence of ovarian cancer. (c) 2006 Wiley-Liss, Inc.
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| 27. |
- Masciari, S., et al.
(författare)
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Germline E-cadherin mutations in familial lobular breast cancer
- 2007
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Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 44:11, s. 726-731
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Tidskriftsartikel (refereegranskat)abstract
- Background: The cell surface glycoprotein E-cadherin (CDH1) is a key regulator of adhesive properties in epithelial cells. Germline mutations in CDH1 are well established as the defects underlying hereditary diffuse gastric cancer (HDGC) syndrome, and an increased risk of lobular breast cancer (LBC) has been described in HDGC kindreds. However, germline CDH1 mutations have not been described in patients with LBC in non-HDGC families. This study aimed to investigate the frequency of germline CDH1 mutations in patients with LBC with early onset disease or family histories of breast cancer without DGC. Methods: Germline DNA was analysed in 23 women with invasive lobular or mixed ductal and lobular breast cancers who had at least one close relative with breast cancer or had themselves been diagnosed before the age of 45 years, had tested negative for a germline BRCA1 or BRCA2 mutation, and reported no personal or family history of diffuse gastric cancer. The full coding sequence of CDH1 including splice junctions was amplified using PCR and screened for mutations using DHPLC and sequencing. Results: A novel germline CDH1 truncating mutation in the extracellular portion of the protein (517insA) was identified in one woman who had LBC at the age of 42 years and a first degree relative with invasive LBC. Conclusions: Germline CDH1 mutations can be associated with invasive LBC in the absence of diffuse gastric cancer. The finding, if confirmed, may have implications for management of individuals at risk for this breast cancer subtype. Clarification of the cancer risks in the syndrome is essential.
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| 28. |
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| 29. |
- Andersson, V., et al.
(författare)
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Large-Area Balloon-Borne Polarized Gamma Ray Observer (PoGO)
- 2005
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Ingår i: Proceedings of the 22nd Texas Symposium on Relativistic Astrophysics at Stanford. ; , s. 736-743
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Konferensbidrag (refereegranskat)abstract
- We are developing a new balloon-borne instrument (PoGO), to measure polarization of soft gamma rays (30-200 keV) using asymmetry in azimuth angle distribution of Compton scattering. PoGO is designed to detect 10 % polarization in 100mCrab sources in a 6-8 hour observation and bring a new dimension to studies on gamma ray emission/transportation mechanism in pulsars, AGNs, black hole binaries, and neutron star surface. The concept is an adaptation to polarization measurements of well-type phoswich counter consisting of a fast plastic scintillator (the detection part), a slow plastic scintillator (the active collimator) and a BGO scintillator (the bottom anti-counter). PoGO consists of close-packed array of 217 hexagonal well-type phoswich counters and has a narrow field-of-view (~ 5 deg2) to reduce possible source confusion. A prototype instrument has been tested in the polarized soft gamma-ray beams at Advanced Photon Source (ANL) and at Photon Factory (KEK). On the results, the polarization dependence of EGS4 has been validated and that of Geant4 has been corrected.
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| 30. |
- Axelsson, Magnus, et al.
(författare)
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Measuring energy dependent polarization in soft gamma-rays using compton scattering in PoGOLite
- 2007
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Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 28:3, s. 327-337
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Tidskriftsartikel (refereegranskat)abstract
- Linear polarization in X-and gamma-rays is an important diagnostic of many astrophysical sources, foremost giving information about their geometry, magnetic fields, and radiation mechanisms. However, very few X-ray polarization measurements have been made, and then only mono-energetic detections, whilst several objects are assumed to have energy dependent polarization signatures. In this paper, we investigate whether detection of energy dependent polarization from cosmic sources is possible using the Compton technique, in particular with the proposed PoGOLite balloon-experiment, in the 25-100 keV range. We use Geant4 simulations of a PoGOLite model and input photon spectra based on Cygnus X-1 and accreting magnetic pulsars (100 mCrab). Effective observing times of 6 and 35 h were simulated, corresponding to a standard and a long duration flight, respectively. Both smooth and sharp energy variations of the polarization are investigated and compared to constant polarization signals using chi-square statistics. We can reject constant polarization, with energy, for the Cygnus X-1 spectrum (in the hard state), if the reflected component is assumed to be completely polarized, whereas the distinction cannot be made for weaker polarization. For the accreting pulsar, constant polarization can be rejected in the case of polarization in a narrow energy band with at least 50% polarization, and similarly for a negative step distribution from 30% to 0% polarization.
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| 31. |
- Cavalieri, A L, et al.
(författare)
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Clocking femtosecond X rays.
- 2005
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Ingår i: Phys Rev Lett. - 0031-9007. ; 94:11
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Tidskriftsartikel (refereegranskat)abstract
- Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.
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| 32. |
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| 33. |
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| 34. |
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| 35. |
- Ehlerding, A., et al.
(författare)
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The dissociative recombination of fluorocarbon ions III : CF2+ and CF3
- 2006
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 39:4, s. 805-812
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Tidskriftsartikel (refereegranskat)abstract
- Cross sections and branching ratios are presented for the dissociative recombination of the CF2+ and C-3(+) ions with electrons. It is found that the channel producing CF + F is dominant for the reaction with CF2+ and the production of CF2 + F is dominant for the reaction with CF3+. The cross sections for these two ions are very similar.
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Itoh, Fumiko, et al.
(författare)
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Poor vessel formation in embryos from knock-in mice expressing ALK5 with L45 loop mutation defective in Smad activation
- 2009
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Ingår i: Laboratory Investigation. - : Elsevier BV. - 1530-0307 .- 0023-6837. ; 89:7, s. 800-810
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor (TGF)-beta regulates vascular development through two type I receptors: activin receptor-like kinase (ALK) 1 and ALK5, each of which activates a different downstream Smad pathway. The endothelial cell (EC)-specific ALK1 increases EC proliferation and migration, whereas the ubiquitously expressed ALK5 inhibits both of these processes. As ALK1 requires the kinase activity of ALK5 for optimal activation, the lack of ALK5 in ECs results in defective phosphorylation of both Smad pathways on TGF-beta stimulation. To understand why TGF-beta signaling through ALK1 and ALK5 has opposing effects on ECs and whether this takes place in vivo, we carefully compared the phenotype of ALK5 knock-in (ALK5(KI/KI)) mice, in which the aspartic acid residue 266 in the L45 loop of ALK5 was replaced by an alanine residue, with the phenotypes of ALK5 knock-out (ALK5(-/-)) and wild-type mice. The ALK5(KI/KI) mice showed angiogenic defects with embryonic lethality at E10.5-11.5. Although the phenotype of the ALK5(KI/KI) mice was quite similar to that of the ALK5(-/-) mice, the hierarchical structure of blood vessels formed in the ALK5(KI/KI) embryos was more developed than that in the ALK5(-/-) mutants. Thus, the L45 loop mutation in ALK5 partially rescued the earliest vascular defects in the ALK5(-/-) embryos. This study supports our earlier observation that vascular maturation in vivo requires both TGF-beta/ALK1/BMP-Smad and TGF-beta/ALK5/activin-Smad pathways for normal vascular development. Laboratory Investigation (2009) 89, 800-810; doi:10.1038/labinvest.2009.37; published online 27 April 2009
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| 41. |
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| 42. |
- Mårtensson, T, et al.
(författare)
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III-V nanowires on Si and nanowire arrays
- 2005
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Ingår i: Book of abstracts: 342nd WE-Heraeus-Seminar Sci and Technol of Inorganic Nanowires, Bad Honnef, Germany (2005).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 43. |
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| 44. |
- Novotny, O, et al.
(författare)
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The dissociative recombination of fluorocarbon ions : II. CF
- 2005
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 38:10, s. 1471-1482
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Tidskriftsartikel (refereegranskat)abstract
- The dissociative recombination and excitation of CF+ have been measured at the ASTRID and CRYRING storage rings. Though examination of the available potential energy curves would suggest that the recombination rate would be large for this ion, in fact a rate constant of 5.2 +/- 1.0 x 10(-8) (T-e/300)(-0.8) cm(3) s(-1) was found. The recombination cross section at low energies falls off to a minimum at 0.5 eV centre-of-mass collision energy but exhibits resonances at energies above this. The dissociative excitation cross section leading to C+ + F was also measured and this displays an onset beginning at about 7 eV.
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| 45. |
- Olsén, L., et al.
(författare)
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Cetirizine in horses : pharmacokinetics and effect of ivermectin pretreatment
- 2007
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Ingår i: Journal of Veterinary Pharmacology and Therapeutics. - : Wiley. - 0140-7783 .- 1365-2885. ; 30:3, s. 194-200
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Tidskriftsartikel (refereegranskat)abstract
- The pharmacokinetics of the histamine H1-antagonist cetirizine and the effects of pretreatment with the antiparasitic macrocyclic lactone ivermectin on the pharmacokinetics of cetirizine were studied in horses. After oral administration of cetirizine at 0.2 mg/kg bw, the mean terminal half-life was 3.4 h (range 2.9–3.7 h) and the maximal plasma concentration 132 ng/mL (101–196 ng/mL). The time to reach maximal plasma concentration was 0.7 h (0.5–0.8 h). Ivermectin (0.2 mg/kg bw) given orally 1.5 h before cetirizine did not affect its pharmacokinetics. However, ivermectin pretreatment 12 h before cetirizine increased the area under the plasma concentration–time curve by 60%. The maximal plasma concentration, terminal half-life and mean residence time also increased significantly following the 12 h pretreatment. Ivermectin is an inhibitor of P-glycoprotein, which is a major drug efflux transporter in cellular membranes at various sites. The elevated plasma levels of cetirizine following the pretreatment with ivermectin may mainly be due to decreased renal secretion, related to inhibition of the P-glycoprotein in the proximal tubular cells of the kidney. The pharmacokinetic properties of cetirizine have characteristics which are suitable for an antihistamine, and this substance may be a useful drug in horses.
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| 46. |
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| 47. |
- Pearce, Mark, et al.
(författare)
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PoGOLite : A balloon-borne soft gamma-ray polarimeter
- 2007
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Ingår i: Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007. - : Universidad Nacional Autonoma de Mexico. ; , s. 479-482
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Konferensbidrag (refereegranskat)abstract
- Polarized gamma-rays are expected from a wide variety of sources including rotationpowered pulsars, accreting black holes and neutron stars, and jet-dominated active galaxies. Polarization measurements provide a powerful probe of the gamma-ray emission mechanism and the distribution of magnetic and radiation fields around the source. No measurements have been performed in the soft gamma-ray band where non-thermal processes are expected to produce high degrees of polarization. The PoGOLite experiment applies well-type phoswich detector technology to polarization measurements in the 25 - 80 keV energy range. The instrument uses Compton scattering and photoabsorption in an array of 217 phoswich detector cells made of plastic and BGO scintillators, and surrounded by active BGO shields. A prototype of the flight instrument has been tested with polarized gammarays and background generated with radioactive sources. The test results and computer simulations confirm that the instrument can detect 10% polarization of a 200 mCrab source in one 6 hour balloon observation. In flight, targets are constrained to within better than 5% of the field-of-view (~5 degrees squared) in order to maximize the effective detection area during observations. The pointing direction on the sky is determined by an attitude control system comprising star trackers, differential GPS receiver system, gyroscopes, accelerometers and magnetometers which provide correction signals to a reaction wheel and torque motor system. Additionally, the entire polarimeter assembly rotates around its viewing axis to minimize systematic bias during observations. Flights are foreseen to start in 2009- 2010 and will target northern sky sources including the Crab pulsar/nebula, Cygnus X-1, and Hercules X-1. These observations will provide valuable information about the pulsar emission mechanism, the geometry around the black hole, and photon transportation in the strongly magnetized neutron star surface, respectively. Future goals include a long duration balloon flight from the Esrange facility in Northern Sweden to Canada.
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| 48. |
- Ryman, N., et al.
(författare)
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Power for detecting genetic divergence: differences between statistical methods and marker loci
- 2006
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Ingår i: Molecular Ecology. - 0962-1083. ; 15:8, s. 2031-2045
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Tidskriftsartikel (refereegranskat)abstract
- Information on statistical power is critical when planning investigations and evaluating empirical data, but actual power estimates are rarely presented in population genetic studies. We used computer simulations to assess and evaluate power when testing for genetic differentiation at multiple loci through combining test statistics or P values obtained by four different statistical approaches, viz. Pearson's chi-square, the log-likelihood ratio G-test, Fisher's exact test, and an F-ST-based permutation test. Factors considered in the comparisons include the number of samples, their size, and the number and type of genetic marker loci. It is shown that power for detecting divergence may be substantial for frequently used sample sizes and sets of markers, also at quite low levels of differentiation. The choice of statistical method may be critical, though. For multi-allelic loci such as microsatellites, combining exact P values using Fisher's method is robust and generally provides a high resolving power. In contrast, for few-allele loci (e.g. allozymes and single nucleotide polymorphisms) and when making pairwise sample comparisons, this approach may yield a remarkably low power. In such situations chi-square typically represents a better alternative. The G-test without Williams's correction frequently tends to provide an unduly high proportion of false significances, and results from this test should be interpreted with great care. Our results are not confined to population genetic analyses but applicable to contingency testing in general.
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| 49. |
- Tanaka, T., et al.
(författare)
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Data acquisition system for the PoGOLite astronomical hard X-ray polarimeter
- 2007
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Ingår i: Nuclear Science Symposium Conference Record, 2007. - 9781424409228 ; , s. 445-449, s. 445-449
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The PoGOLite is a new balloon-borne instrument to measure the polarization of hard X-rays/soft gamma-rays in the 25-80 keV energy range for the first time. In order to detect the polarization, PoGOLite measures the azimuthal angle asymmetry of Compton scattering and the subsequent photo-absorption in an array of detectors. This array consists of 217 well-type phoswich detector cells (PDCs) surrounded by a side anti-coincidence shield (SAS) composed of 54 segments of BGO crystals. At balloon altitude, the intensity of backgrounds due to cosmic-ray charged particles, atmospheric gamma-rays and neutrons is extremely high, typically a few hundred Hz per unit. Hence the data acquisition (DAQ) system of PoGOLite is required to handle more than 270 signals simultaneously, and detect weak signals from astrophysical objects (100mCrab, 1.5 cs(-1) in 25-80 keV) under such a severe environment. We have developed a new DAQ system consisting of front-end electronics, waveform digitizer, Field Programmable Gate Array (FPGA) and a microprocessor. In this system, all output signals of PDC / SAS are fed into individual charge-sensitive amplifier and then digitized to 12 bit accuracy at 24 MSa/s by pipelined analog to digital converters. A DAQ board for the PDC records waveforms which will be examined in an off-line analysis to distinguish signals from the background events and measure the energy spectrum and polarization of targets. A board for the SAS records hit pattern to be used for background rejection. It also continuously records a pulse-height analysis (PHA) histogram to monitor incident background flux. These basic functions of the DAQ system were verified in a series of beam tests.
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| 50. |
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