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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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- Abdesselam, A., et al.
(författare)
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The ATLAS semiconductor tracker end-cap module
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 575:3, s. 353-389
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Tidskriftsartikel (refereegranskat)abstract
- The challenges for the tracking detector systems at the LHC are unprecedented in terms of the number of channels, the required read-out speed and the expected radiation levels. The ATLAS Semiconductor Tracker. (SCT) end-caps have a total of about 3 million electronics channels each reading out every 25 ns into its own on-chip 3.3 mu s buffer. The highest anticipated dose after 10 years operation is 1.4x10(14) cm(-2) in units of 1 MeV neutron equivalent (assuming the damage factors scale with the non-ionising energy loss). The forward tracker has 1976 double-sided modules, mostly of area similar to 70 cm(2), each having 2 x 768 strips read out by six ASICs per side. The requirement to achieve an average perpendicular radiation length of 1.5% X-0, while coping with up to 7 W dissipation per module (after irradiation), leads to stringent constraints on the thermal design. The additional requirement of 1500e(-) equivalent noise charge (ENC) rising to only 1800e(-) ENC after irradiation, provides stringent design constraints on both the high-density Cu/Polyimide flex read-out circuit and the ABCD3TA read-out ASICs. Finally, the accuracy of module assembly must not compromise the 16 mu m (r phi) resolution perpendicular to the strip directions or 580 mu m radial resolution coming from the 40 mrad front-back stereo angle. A total of 2210 modules were built to the tight tolerances and specifications required for the SCT. This was 234 more than the 1976 required and represents a yield of 93%. The component flow was at times tight, but the module production rate of 40-50 per week was maintained despite this. The distributed production was not found to be a major logistical problem and it allowed additional flexibility to take advantage of where the effort was available, including any spare capacity, for building the end-cap modules. The collaboration that produced the ATLAS SCT end-cap modules kept in close contact at all times so that the effects of shortages or stoppages at different sites could be rapidly resolved.
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- 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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- Pirozhkov, A. S., et al.
(författare)
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Diagnostic of laser contrast using target reflectivity
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:24
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Tidskriftsartikel (refereegranskat)abstract
- Using three different laser systems, we demonstrate a convenient and simple plasma based diagnostic of the contrast of high-power short-pulse lasers. The technique is based on measuring the specular reflectivity from a solid target. The reflectivity remains high even at relativistic intensities above 10(19) W/cm(2) in the case of a high-contrast prepulse-free laser. On the contrary, the specular reflectivity drops with increasing intensities in the case of systems with insufficient contrast due to beam breakup and increased absorption caused by preplasma.
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- Carroll, Thomas X., et al.
(författare)
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Fluorine as a π donor. Carbon 1s photoelectron spectroscopy and proton affinities of fluorobenzenes
- 2006
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 71:5, s. 1961-1968
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Tidskriftsartikel (refereegranskat)abstract
- The carbon 1s ionization energies for all of the carbon atoms in 10 fluorine-substituted benzene molecules have been measured by high-resolution photoelectron spectroscopy. A total of 30 ionization energies can be accurately described by an additivity model with four parameters that describe the effect of a fluorine that is ipso, ortho, meta, or para to the site of ionization. A similar additivity relationship describes the enthalpies of protonation. The additivity parameters reflect the role of fluorine as an electron-withdrawing group and as a π-electron donating group. The ionization energies and proton affinities correlate linearly, but there are four different correlations depending on whether there are 0, 1, 2, or 3 fluorines ortho or para to the site of ionization or protonation. That there are four correlation lines can be understood in terms of the ability of the hydrogens at the site of protonation to act as a π-electron acceptor. A comparison of the ionization energies and proton affinities, together with the results of electronic structure calculations, gives insight into the effects of fluorine as an electron-withdrawing group and as a π donor, both in the neutral molecule and in response to an added positive charge.
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- Walker, M. D., et al.
(författare)
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Plant community responses to experimental warming across the tundra biome
- 2006
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 103:5, s. 1342-1346
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Tidskriftsartikel (refereegranskat)abstract
- Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, including warming; however, most studies were limited to a single location and were of short duration and based on a variety of experimental designs. In addition, comparisons among studies are difficult because a variety of techniques have been used to achieve experimental warming and different measurements have been used to assess responses. We used metaanalysis on plant community measurements from standardized warming experiments at 11 locations across the tundra biome involved in the International Tundra Experiment. The passive warming treatment increased plant-level air temperature by 1-3 degrees C, which is in the range of predicted and observed warming for tundra regions. Responses were rapid and detected in whole plant communities after only two growing seasons. Overall, warming increased height and cover of deciduous shrubs and graminoids, decreased cover of mosses and lichens, and decreased species diversity and evenness. These results predict that warming will cause a decline in biodiversity across a wide variety of tundra, at least in the short term. They also provide rigorous experimental evidence that recently observed increases in shrub cover in many tundra regions are in response to climate warming. These changes have important implications for processes and interactions within tundra ecosystems and between tundra and the atmosphere.
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- Carroll, Linda J., et al.
(författare)
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Recovery in Whiplash-Associated Disorders : Do You Get What You Expect?
- 2009
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Ingår i: Journal of Rheumatology. - : The Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 36:5, s. 1063-1070
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Positive expectations predict better outcome in a number of health conditions, but the role of expectations in predicting health recovery after injury is not Well understood. We investigated whether early expectations of recovery in whiplash associated disorders (WAD) predict subsequent recovery, and Studied the role of "expectations" to predict recovery as determined by pain cessation and resolution of pain-related limitations in daily activities. Methods. A cohort of 6,015 adults With traffic-related whiplash injuries was assessed, using multivariable Cox proportional hazards analysis, for association between these expectations and self-perceived recovery over a 1-year period following the injury. Recovery was assessed using 3 indices: self-perceived global recovery (primary outcome), resolution of neck pain severity; and resolution of pain-related limitations in daily activities. Results. After adjusting for the effect of sociodemographic characteristics, post-crash symptoms and pain, prior health status and collision-related factors, those who expected to get better soon recovered over 3 times as quickly (hazard rate ratio = 3.62, 95% confidence interval 2.55-5.13) as those who expected that they Would never get better. Findings were similar for resolution of pain-related limitations and resolution of neck pain intensity, although the effect sizes for the latter outcome were smaller. Conclusion. Patients' early expectations for recovery are all important prognostic factor in recovery after whiplash injury, and are potentially modifiable. Clinicians should assess these expectations ill order to identify those patients at risk of chronic whiplash, and future Studies should focus Oil the effect of changing these early expectations. (First Release Feb 15 2009; J Rheumatol 2009;36:1063-70; doi: 10.3899/jrheum.080680)
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- Dall'Era, Marc A., et al.
(författare)
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Active surveillance for early-stage prostate cancer : review of the current literature
- 2008
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Ingår i: Cancer. - : Wiley. - 0008-543X .- 1097-0142. ; 112:8, s. 1650-9
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Tidskriftsartikel (refereegranskat)abstract
- The natural history of prostate cancer is remarkably heterogeneous and, at this time, not completely understood. The widespread adoption and application of prostate-specific antigen (PSA) screening has led to a dramatic shift toward the diagnosis of low-volume, nonpalpable, early-stage tumors. Autopsy and early observational studies have shown that approximately 1 in 3 men aged >50 years has histologic evidence of prostate cancer, with a significant portion of tumors being small and possibly clinically insignificant. Utilizing the power of improved contemporary risk stratification schema to better identify patients with a low risk of cancer progression, several centers are gaining considerable experience with active surveillance and delayed, selective, and curative therapy. A literature review was performed to evaluate the rationale behind active surveillance for prostate cancer and to describe the early experiences from surveillance protocols. It appears that a limited number of men on active surveillance have required treatment, with the majority of such men having good outcomes after delayed selective intervention for progressive disease. The best candidates for active surveillance are being defined, as are predictors of active treatment. The psychosocial ramifications of surveillance for prostate cancer can be profound and future needs and unmet goals will be discussed.
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- Descartes, Maria, et al.
(författare)
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Distal 22q11.2 microduplication encompassing the BCR gene
- 2008
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Ingår i: American journal of medical genetics. Part A. - : Wiley. - 1552-4825 .- 1552-4833. ; 146A:23, s. 3075-3081
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Tidskriftsartikel (refereegranskat)abstract
- Chromosome 22 band q11.2 has been recognized to be highly susceptible to subtle microdeletions and microduplications, which have been attributed to the presence of several large segmental duplications; also known as low copy repeats (LCRs). These LCRs function as mediators of non-allelic homologous recombination (NAHR), which results in these chromosomal rearrangements as a result of unequal crossover. The four centromeric LCRs at proximal 22q11.2 have been previously implicated in recurrent chromosomal rearrangements including the DiGeorge/Velocardiofacial syndrome (DG/VCFs) microdeletion and its reciprocal microduplication. Recently, we and others have demonstrated that the four telomeric LCRs at distal 22q11.2 are causally implicated in a newly recognized recurrent distal 22q11.2 microdeletion syndrome in the region immediately telomeric to the DG/VCFs typically deleted region. Here we report on the clinical, cytogenetic, and array CGH studies of a 4.5-year-old girl with history of failure to thrive, developmental delay (DD), and relative macrocephaly. She carries a paternally inherited approximately 2.1 Mb microduplication at distal 22q11.2, which spans approximately 34 annotated genes, and is flanked by two of the four telomeric 22q11.2 LCRs. We conclude that the four telomeric LCRs at distal 22q11.2 can mediate both deletions and duplications in this genomic region. Both deletions and duplication of this region present with subtle clinical features including mild to moderate mental retardation, DD, and mild dysmorphic features.
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