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- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Elsik, Christine G., et al.
(författare)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 9. |
- von Brömssen, Mattias, et al.
(författare)
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Targeting low-arsenic aquifers in Matlab Upazila, Southeastern Bangladesh
- 2007
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 375:2-3, s. 121-132
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater with high concentration of geogenic arsenic (As) occurs extensively in the Holocene alluvial aquifers of Bangladesh. Local drillers in Matlab Upazilla are constructing deeper tubewells than in the recent past, primarily because of low concentrations of dissolved Fe and As. Locally a thick layer of black to grey sediments overlies an oxidised unit of yellowish-grey to reddish-brown sediments. The correlation between the colour of both units and the groundwater redox conditions was investigated to provide an easy tool for targeting low-arsenic groundwater. Based on the sediment colour at the screen depths described by local drillers, 40 domestic shallow tubewells were selected for water sampling. Four colours were used to describe the sediments: black, white, off-white (buff) and red. Generally, the groundwater was anoxic and the As concentrations ranged from less than 5.2 to 355 mu g/L. Water derived from the black sediment is characterized by relatively higher concentrations of dissolved NH4+, DOC, Fe, P, As and by low Mn and SO42- concentrations. The off-white and red sediments had high concentration of Mn and low NH4+, DOC, Fe, P and As concentrations. The water abstracted from the black sediments indicated the most reducing environment, followed by white, off-white and red respectively. Three boreholes verified the driller's perception of the subsurface lithologic conditions. Discrepancies between the driller's and the research team description of the sediment colours were insignificant. This study shows that sediment colour is a reliable indicator of high and low-As concentrations and can be used by local drillers to target low-arsenic groundwater.
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| 10. |
- Bhattacharya, Prosun, et al.
(författare)
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Groundwater chemistry and arsenic mobilization in the Holocene flood plains in south-central Bangladesh
- 2009
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Ingår i: Environmental Geochemistry and Health. - : Springer Science and Business Media LLC. - 0269-4042 .- 1573-2983. ; 31, s. 23-43
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Tidskriftsartikel (refereegranskat)abstract
- A comparative study of arsenic enrichment in the Bengal Delta (BD) was carried Out in three alluvial aquifers in south-central Bangladesh. Investigated sites included Sonargaon in Narayanganj, Chandina in Comilla and Sirajdikhan in Munshiganj districts. At all sites samples from different depths were collected, and water chemistry and redox status vs. depth trends were determined. The concentrations of DOC and HCO3- were highest at Sirajdikhan site, while at the Sonargaon and Chandina sites the concentrations were lower. On the contrary, the NH4+ concentration was high at the Chandina site as compared to the other sites. There was a good match between dissolved As and Fe at the Sirajdikhan and Sonargaon sites, but not at the Chandina site. The dissolved aqueous concentration of Mn was low at the Chandina site, which suggested that the Mn(IV) redox buffering step was missing. Speciation modeling indicated a possibility of siderite precipitation at all sites, but precipitation of rhodochrosite only at the Sonargaon and Sirajdikhan sites. At the Sirajdikhan site, the log P-CO2 values were very high (-1.37), which revealed the production Of CO2 in redox processes. Principal component analysis (PCA) indicated an impact of sea water and redox status of different samples. These results suggest that the dissolved As is de-coupled from dissolved Mn because when released, As is re-adsorbed onto the Fe(Ill) minerals in solid phase, as well as from dissolved Fe when precipitation of Fe(II) minerals controls the aqueous concentrations of Fe. In addition, several other concurrent redox processes may exert kinetic constraints depending on refractory characteristics of Fe(II) minerals.
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| 11. |
- Hasan, Md. Aziz, 1960-, et al.
(författare)
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Arsenic in shallow groundwater of Bangladesh : investigations from three different physiographic settings
- 2007
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Ingår i: Hydrogeology Journal. - : Springer Science and Business Media LLC. - 1431-2174 .- 1435-0157. ; 15:8, s. 1507-1522
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Tidskriftsartikel (refereegranskat)abstract
- Occurrences of arsenic (As) in the Bengal Basin of Bangladesh show close relationships with depositional environments and sediment textures. Hydrochemical data from three sites with varying physiography and sedimentation history show marked variations in redox status and dissolved As concentrations. Arsenic concentration in groundwater of the Ganges Flood Plain (GFP) is characteristically low, where high Mn concentrations indicate redox buffering by reduction of Mn(IV)-oxyhydroxides. Low DOC, HCO3-, NH4+ and high NO3- and So(4)(2-) concentrations reflect an elevated redox status in GFP aquifers. In contrast, As concentration in the Ganges Delta Plain (GDP) is very high along with high Fe and low Mn. In the Meghna Flood Plain (MFP), moderate to high As and Fe concentrations and low Mn are detected. Degradation of organic matter probably drives redox reactions in the aquifers, particularly in MFP and GDP, thereby mobilising dissolved As. Speciation calculations indicate supersaturation with respect to siderite and vivianite in the groundwater samples at MFP and GDP, but groundwater in the GFP wells is generally supersaturated with respect to rhodochrosite. Values of log P-CO2 at MFP and GDP sites are generally higher than at the GFP site. This is consistent with Mn(IV)-redox buffering suggested at the GFP site compared to Fe(III)-redox buffering at MFP and GDP sites.
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- Lalani, Tahaniyat, et al.
(författare)
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Propionibacterium endocarditis: a case series from the International Collaboration on Endocarditis Merged Database and Prospective Cohort Study.
- 2007
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Ingår i: Scandinavian journal of infectious diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 39:10, s. 840-8
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Tidskriftsartikel (refereegranskat)abstract
- Propionibacterium species are occasionally associated with serious systemic infections such as infective endocarditis. In this study, we examined the clinical features, complications and outcome of 15 patients with Propionibacterium endocarditis using the International Collaboration on Endocarditis Merged Database (ICE-MD) and Prospective Cohort Study (ICE-PCS), and compared the results to 28 cases previously reported in the literature. In the ICE database, 11 of 15 patients were male with a mean age of 52 y. Prosthetic valve endocarditis occurred in 13 of 15 cases and 3 patients had a history of congenital heart disease. Clinical findings included valvular vegetations (9 patients), cardiac abscesses (3 patients), congestive heart failure (2 patients), and central nervous system emboli (2 patients). Most patients were treated with beta-lactam antibiotics alone or in combination for 4 to 6 weeks. 10 of the 15 patients underwent valve replacement surgery and 2 patients died. Similar findings were noted on review of the literature. The results of this paper suggest that risk factors for Propionibacterium endocarditis include male gender, presence of prosthetic valves and congenital heart disease. The clinical course is characterized by complications such as valvular dehiscence, cardiac abscesses and congestive heart failure. Treatment may require a combination of medical and surgical therapy.
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