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- Amsler, C., et al.
(författare)
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Review of particle physics
- 2008
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 667:1-5, s. 1-1
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Forskningsöversikt (refereegranskat)abstract
- This biennial Review summarizes much of particle physics. Using data from previous editions., plus 2778 new measurements from 645 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors., probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on CKM quark-mixing matrix, V-ud & V-us, V-cb & V-ub, top quark, muon anomalous magnetic moment, extra dimensions, particle detectors, cosmic background radiation, dark matter, cosmological parameters, and big bang cosmology.
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| 2. |
- Raiteri, C. M., et al.
(författare)
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WEBT and XMM-Newton observations of 3C 454.3 during the post-outburst phase - Detection of the little and big blue bumps
- 2007
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 473:3, s. 819-827
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Tidskriftsartikel (refereegranskat)abstract
- Context. The quasar-type blazar 3C 454.3 was observed to undergo an unprecedented optical outburst in spring 2005, affecting the source brightness from the near-IR to the X-ray frequencies. This was first followed by a millimetric and then by a radio outburst, which peaked in February 2006. Aims. In this paper we report on follow-up observations to study the multiwavelength emission in the post-outburst phase. Methods. Radio, near-infrared, and optical monitoring was performed by the Whole Earth Blazar Telescope (WEBT) collaboration in the 2006-2007 observing season. XMM-Newton observations on July 2-3 and December 18-19, 2006 added information on the X-ray and UV states of the source. Results. The source was in a faint state. The radio flux at the higher frequencies showed a fast decreasing trend, which represents the tail of the big radio outburst. It was followed by a quiescent state, common at all radio frequencies. In contrast, moderate activity characterized the near-IR and optical light curves, with a progressive increase of the variability amplitude with increasing wavelength. We ascribe this redder-when-brighter behaviour to the presence of a ""little blue bump"" due to line emission from the broad line region, which is clearly visible in the source spectral energy distribution (SED) during faint states. Moreover, the data from the XMM- Newton Optical Monitor reveal a rise of the SED in the ultraviolet, suggesting the existence of a "" big blue bump"" due to thermal emission from the accretion disc. The X-ray spectra are well fitted with a power- law model with photoelectric absorption, possibly larger than the Galactic one. However, the comparison with previous X-ray observations would imply that the amount of absorbing matter is variable. Alternatively, the intrinsic X-ray spectrum presents a curvature, which may depend on the X-ray brightness. In this case, two scenarios are possible. i) There is no extra absorption, and the X-ray spectrum hardens at low energies, the hardening being more evident in bright states; ii) there is a constant amount of extra absorption, likely in the quasar environment, and the X-ray spectrum softens at low energies, at least in faint X-ray states. This softening might be the result of a flux contribution by the high-frequency tail of the big blue bump.
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| 5. |
- Löwemark, Ludvig, 1969-, et al.
(författare)
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New evidence for a glacioeustatic influence on deep watercirculation, bottom water ventilation and primaryproductivity in the South China Sea
- 2009
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Ingår i: Dynamics of atmospheres and oceans (Print). - : Elsevier. - 0377-0265 .- 1872-6879. ; 47:1-3, s. 138-153
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Tidskriftsartikel (refereegranskat)abstract
- We provide new evidence for the development of a stable estuarinecirculation characterized by stagnating water bodies, nutrientrecycling and increased primary productivity in the South ChinaSea (SCS) during glacial intervals. This circulation was caused bythe closure of the shallow and narrow straits connecting the SCSin the south and west. Our main evidence is derived from newlymeasured Mn concentrations and Mn/Al ratios in two sedimentcores from the northern and southeastern SCS covering the last500 ky. Concentrations and Mn/Al ratios of the redox sensitive elementMnshowclearglacial–interglacial cycles with maxima duringinterglacial periods and minima during glacial periods. These cyclesindicate ventilation cycles of the bottom water, and are connectedto the glacial–interglacial changes in sea level. In contrast, totalorganic carbon (TOC) concentrations display an opposite patternwith pronounced maxima during glacial times, especially in thesouthern part of the basin. The variations in TOC can be ascribed totwo factors. Firstly, variations in primary productivity are controlledby variations in the intensity of the winter monsoon. Secondlyto the degree of preservation of TOC controlled by variations inventilation, which in turn is ultimately controlled by sea level. Consequently, variations in TOC represent a superimposition ofprimarily sea level influenced preservation control and wintermonsoon driven variations in primary productivity intensity. Thedecrease in Mn correspond to times when sea level dropped40–60m below the present level. The larger amplitude of the variationsin TOC and Mn in the southern part of the basin compared tothe northern site suggest that oxygen depletion and nutrient recyclingwas stronger in the parts of the basin situated the furthest away from the only remaining opening to the open Pacific, the LuzonStrait.
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| 6. |
- Yang, T, et al.
(författare)
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Fe5O5[B6O10(OH)3]·nH2O: Wave-layered Iron Borate and Frustrated Antiferromagnetism
- 2009
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 48:23, s. 11209-11214
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Tidskriftsartikel (refereegranskat)abstract
- The first layered iron borate, Fe5O5[B6O10(OH)3]·nH2O, has been prepared by the boric acid flux method. Its structure, determined by single crystal X-ray diffraction, contains a double FeO6-octahedral layer and an unusual [B6O13] chain. The rigid and cambered [B6O13] chains bend the octahedral layers, resulting in a wave-like and sandwiched structure. Crystallographic study indicates the structural modulation is mainly from the [B6O13] chains because of the insertion of water molecules in between. Nevertheless, FeO6 layers in the average structure, which are well separated by borate chains, is still a reasonable model to understand the two-dimensional magnetism. The strong antiferromagnetic interactions and the complex Fe3+-net suggest a possible geometrically magnetic frustration, which may be the reason for the second-order temperature-induced magnetic transition at 125 K. The condensed Fe3+ layers and the relatively low redox potential at about 1.25 V versus Li+/Li show its potentials as an anodic material.
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| 9. |
- Jiang, Q. H., et al.
(författare)
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High-temperature ferroelectric phase transition observed in multiferroic Bi0.91La0.05Tb0.04FeO3
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 95:1, s. 12909-
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Tidskriftsartikel (refereegranskat)abstract
- A single-phase Bi0.91La0.05Tb0.04FeO3 polycrystalline ceramic was fabricated by spark-plasma-sintering the precursor powder prepared by a sol-gel method. Temperature-dependent properties of polycrystalline Bi0.91La0.05Tb0.04FeO3 were characterized by x-ray diffraction, dielectric, and piezoelectric measurement. The x-ray diffraction results revealed a phase transition near 700 degrees C. Especially, temperature-dependent dielectric behavior demonstrated that there was a dielectric abnormal peak at about 697 degrees C, in addition to those two well-known dielectric abnormal peaks at 337 degrees C (Neel temperature) and 831 degrees C (Curie temperature). The observations, together with thermal depoled behavior, suggest a ferroelectric-ferroelectric phase transition from R(3)c to Pbnm at around 700 degrees C.
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