| 1. |
- Abdesselam, A., et al.
(författare)
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Engineering for the ATLAS SemiConductor Tracker (SCT) end-cap
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS SemiConductor Tracker (SCT) is a silicon-strip tracking detector which forms part of the ATLAS inner detector. The SCT is designed to track charged particles produced in proton-proton collisions at the Large Hadron Collider (LHC) at CERN at an energy of 14 TeV. The tracker is made up of a central barrel and two identical end-caps. The barrel contains 2112 silicon modules, while each end-cap contains 988 modules. The overall tracking performance depends not only on the intrinsic measurement precision of the modules but also on the characteristics of the whole assembly, in particular, the stability and the total material budget. This paper describes the engineering design and construction of the SCT end-caps, which are required to support mechanically the silicon modules, supply services to them and provide a suitable environment within the inner detector. Critical engineering choices are highlighted and innovative solutions are presented - these will be of interest to other builders of large-scale tracking detectors. The SCT end-caps will be fully connected at the start of 2008. Further commissioning will continue, to be ready for proton-proton collision data in 2008.
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| 2. |
- 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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| 3. |
- Coustenis, A., et al.
(författare)
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TandEM : Titan and Enceladus mission
- 2009
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 23:3, s. 893-946
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Tidskriftsartikel (refereegranskat)abstract
- TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (MontgolfiSre) and possibly several landing probes to be delivered through the atmosphere.
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| 4. |
- Richards, Stephen, et al.
(författare)
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The genome of the model beetle and pest Tribolium castaneum.
- 2008
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Ingår i: Nature. - 1476-4687. ; 452:7190, s. 949-55
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Tidskriftsartikel (refereegranskat)abstract
- Tribolium castaneum is a representative of earth’s most numerous eukaryotic order, a powerful model organism for the study of generalized insect development, and also an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved an ability to interact with a diverse chemical environment as evidenced by large expansions in odorant and gustatory receptors, as well as p450 and other detoxification enzymes. Developmental patterns in Tribolium are more representative of other arthropods than those found in Drosophila, a fact represented in gene content and function. For one, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, and some are expressed in the growth zone crucial for axial elongation in short germ development. Systemic RNAi in T. castaneum appears to use mechanisms distinct from those found in C. elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.
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| 7. |
- Stone, Graham N., et al.
(författare)
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Evidence for widespread cryptic sexual generations in apparently purely asexual Andricus gallwasps
- 2008
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 17:2, s. 652-665
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Tidskriftsartikel (refereegranskat)abstract
- Oak gallwasps (Hymenoptera, Cynipidae, Cynipini) are one of seven major animal taxa that commonly reproduce by cyclical parthenogenesis (CP). A major question in research on CP taxa is the frequency with which lineages lose their sexual generations, and diversify as purely asexual radiations. Most oak gallwasp species are only known from an asexual generation, and secondary loss of sex has been conclusively demonstrated in several species, particularly members of the holarctic genus Andricus. This raises the possibility of widespread secondary loss of sex in the Cynipini, and of diversification within purely parthenogenetic lineages. We use two approaches based on analyses of allele frequency data to test for cryptic sexual generations in eight apparently asexual European species distributed through a major western palaearctic lineage of the gallwasp genus Andricus. All species showing adequate levels of polymorphism (7/8) showed signatures of sex compatible with cyclical parthenogenesis. We also use DNA sequence data to test the hypothesis that ignorance of these sexual generations (despite extensive study on this group) results from failure to discriminate among known but morphologically indistinguishable sexual generations. This hypothesis is supported: 35 sequences attributed by leading cynipid taxonomists to a single sexual adult morphospecies, Andricus burgundus, were found to represent the sexual generations of at least six Andricus species. We confirm cryptic sexual generations in a total of 11 Andricus species, suggesting that secondary loss of sex is rare in Andricus.
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| 10. |
- Wolever, Thomas M S, et al.
(författare)
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Measuring the glycemic index of foods: interlaboratory study.
- 2008
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Ingår i: The American journal of clinical nutrition. - 0002-9165 .- 1938-3207. ; 87:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Many laboratories offer glycemic index (GI) services. OBJECTIVE: We assessed the performance of the method used to measure GI. DESIGN: The GI of cheese-puffs and fruit-leather (centrally provided) was measured in 28 laboratories (n=311 subjects) by using the FAO/WHO method. The laboratories reported the results of their calculations and sent the raw data for recalculation centrally. RESULTS: Values for the incremental area under the curve (AUC) reported by 54% of the laboratories differed from central calculations. Because of this and other differences in data analysis, 19% of reported food GI values differed by >5 units from those calculated centrally. GI values in individual subjects were unrelated to age, sex, ethnicity, body mass index, or AUC but were negatively related to within-individual variation (P=0.033) expressed as the CV of the AUC for repeated reference food tests (refCV). The between-laboratory GI values (mean+/-SD) for cheese-puffs and fruit-leather were 74.3+/-10.5 and 33.2+/-7.2, respectively. The mean laboratory GI was related to refCV (P=0.003) and the type of restrictions on alcohol consumption before the test (P=0.006, r2=0.509 for model). The within-laboratory SD of GI was related to refCV (P<0.001), the glucose analysis method (P=0.010), whether glucose measures were duplicated (P=0.008), and restrictions on dinner the night before (P=0.013, r2=0.810 for model). CONCLUSIONS: The between-laboratory SD of the GI values is approximately 9. Standardized data analysis and low within-subject variation (refCV<30%) are required for accuracy. The results suggest that common misconceptions exist about which factors do and do not need to be controlled to improve precision. Controlled studies and cost-benefit analyses are needed to optimize GI methodology. The trial was registered at clinicaltrials.gov as NCT00260858.
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