| 1. |
- Aartsen, M. G., et al.
(author)
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A Combined Maximum-Likelihood Analysis Of The High-Energy Astrophysical Neutrino Flux Measured With Icecube
- 2015
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 809:1
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Journal article (peer-reviewed)abstract
- Evidence for an extraterrestrial flux of high-energy neutrinos has now been found in multiple searches with the IceCube detector. The first solid evidence was provided by a search for neutrino events with deposited energies greater than or similar to 30 TeV and interaction vertices inside the instrumented volume. Recent analyses suggest that the extraterrestrial flux extends to lower energies and is also visible with throughgoing, nu(mu)-induced tracks from the Northern Hemisphere. Here, we combine the results from six different IceCube searches for astrophysical neutrinos in a maximum-likelihood analysis. The combined event sample features high-statistics samples of shower-like and track-like events. The data are fit in up to three observables: energy, zenith angle, and event topology. Assuming the astrophysical neutrino flux to be isotropic and to consist of equal flavors at Earth, the all-flavor spectrum with neutrino energies between 25 TeV and 2.8 PeV is well described by an unbroken power law with best-fit spectral index -2.50 +/- 0.09 and a flux at 100 TeV of (6.7(-1.2)(+1.1)) x 10(-18) GeV-1 s(-1) sr(-1) cm(-2). Under the same assumptions, an unbroken power law with index -2 is disfavored with a significance of 3.8 sigma (p = 0.0066%) with respect to the best fit. This significance is reduced to 2.1 sigma (p = 1.7%) if instead we compare the best fit to a spectrum with index -2 that has an exponential cut-off at high energies. Allowing the electron-neutrino flux to deviate from the other two flavors, we find a nu(e) fraction of 0.18 +/- 0.11 at Earth. The sole production of electron neutrinos, which would be characteristic of neutron-decay-dominated sources, is rejected with a significance of 3.6 sigma ( p = 0.014%).
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| 2. |
- Makela, J., et al.
(author)
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Line shape and composition of the In 3d(5/2) core-level photoemission for the interface analysis of In-containing III-V semiconductors
- 2015
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In: Applied Surface Science. - : Elsevier BV. - 1873-5584 .- 0169-4332. ; 329, s. 371-375
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Journal article (peer-reviewed)abstract
- The In 3d(5/2) photoelectron spectroscopy peak has been widely used to determine the interface structures of In-containing III-V device materials (e.g., oxidation states). However, an unclear parameter affecting the determination of the energy shifts and number of the core-level components, and therefore, the interpreted interface structure and composition, is still the intrinsic In 3d(5/2) peak line shape. It is undecided whether the line shape is naturally symmetric or asymmetric for pure In-containing III-V compounds. By using high-resolution photoelectron spectroscopy, we show that the In 3d(5/2) asymmetry arising from the emission at high binding-energy tail is not an intrinsic property of InAs, InP, InSb and InGaAs. Furthermore, it is shown that asymmetry of In 3d(5/2) peaks of pure III-V's originates from the natural surface reconstructions which cause the coexistence of slightly shifted In 3d(5/2) components with the symmetric peak shape and dominant Lorentzian broadening. (C) 2015 Elsevier B.V. All rights reserved.
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| 3. |
- Folland, Chris K., et al.
(author)
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Multi-annual droughts in the English Lowlands: a review of their characteristics and climate drivers in the winter half-year
- 2015
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In: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 19:5, s. 2353-2375
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Journal article (peer-reviewed)abstract
- The English Lowlands is a relatively dry, densely populated region in the south-east of the UK in which water is used intensively. Consequently, parts of the region are water-stressed and face growing water resource pressures. The region is heavily dependent on groundwater and particularly vulnerable to long, multi-annual droughts primarily associated with dry winters. Despite this vulnerability, the atmospheric drivers of multi-annual droughts in the region are poorly understood, an obstacle to developing appropriate drought management strategies, including monitoring and early warning systems. To advance our understanding, we assess known key climate drivers in the winter half-year (October-March) and their likely relationships with multi-annual droughts in the region. We characterise historic multi-annual drought episodes back to 1910 for the English Lowlands using various meteorological and hydrological data sets. Multi-annual droughts are identified using a gridded precipitation series for the entire region, and refined using the Standardized Precipitation Index (SPI), Standardized Streamflow Index (SSI) and Standardized Groundwater level Index (SGI) applied to regional-scale river flow and groundwater time series. We explore linkages between a range of potential climatic driving factors and precipitation, river flow and groundwater level indicators in the English Lowlands for the winter half-year. The drivers or forcings include El Nino-Southern Oscillation (ENSO), the North Atlantic tripole sea surface temperature (SST) pattern, the Quasi-Biennial Oscillation (QBO), solar and volcanic forcing and the Atlantic Multi-decadal Oscillation (AMO). As expected, no single driver convincingly explains the occurrence of any multi-annual drought in the historical record. However, we demonstrate, for the first time, an association between La Nina episodes and winter rainfall deficits in some major multi-annual drought episodes in the English Lowlands. We also show significant (albeit relatively weak) links between ENSO and drought indicators applied to river flow and groundwater levels. We also show that some of the other drivers listed above are likely to influence English Lowlands rainfall. We conclude by signposting a direction for this future research effort.
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