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| 2. |
- Abdo, A. A., et al.
(författare)
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The second Fermi large area telescope catalog of gamma-ray pulsars
- 2013
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 208:2, s. 17-
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Tidskriftsartikel (refereegranskat)abstract
- This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.
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| 3. |
- Dahl-Jensen, D., et al.
(författare)
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Eemian interglacial reconstructed from a Greenland folded ice core
- 2013
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 493:7433, s. 489-494
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Tidskriftsartikel (refereegranskat)abstract
- Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
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| 4. |
- Horn, M. A., et al.
(författare)
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Screening for X-linked adrenoleukodystrophy among adult men with Addison's disease
- 2013
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Ingår i: Clinical Endocrinology. - : Wiley. - 0300-0664. ; 79:3, s. 316-320
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesX-linked adrenoleukodystrophy is an important cause of Addison's disease in boys, but less is known about its contribution to Addison's disease in adult men. After surveying all known cases of X-linked adrenoleukodystrophy in Norway in a separate study, we aimed to look for any missed cases among the population of adult men with nonautoimmune Addison's disease. Study designAmong 153 adult men identified in a National Registry for Addison's Disease (75% of identified male cases of Addison's disease in Norway), those with negative indices for 21-hydroxylase autoantibodies were selected. Additionally, cases with low autoantibody indices (48-200) were selected. Sera from subjects included were analysed for levels of very long-chain fatty acids, which are diagnostic for X-linked adrenoleukodystrophy in men. ResultsEighteen subjects had negative indices and 17 had low indices for 21-hydroxylase autoantibodies. None of those with low indices and only one of those with negative indices were found to have X-linked adrenoleukodystrophy; this subject had already been diagnosed because of the neurological symptoms. Cases of Addison's disease proved to be caused by X-linked adrenoleukodystrophy constitute 15% of all adult male cases in Norway; the proportion among nonautoimmune cases was 15%. ConclusionsWe found X-linked adrenoleukodystrophy to be an uncommon cause of Addison's disease in adult men. However, this aetiological diagnosis has far-reaching consequences both for the patient and for his extended family. We therefore recommend that all adult men with nonautoimmune Addison's disease be analysed for levels of very long-chain fatty acids.
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| 6. |
- Sime, Louise C., et al.
(författare)
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Southern Hemisphere westerly wind changes during the Last Glacial Maximum : model-data comparison
- 2013
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 64, s. 104-120
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Tidskriftsartikel (refereegranskat)abstract
- The Southern Hemisphere (SH) westerly winds are thought to be critical to global ocean circulation, productivity, and carbon storage. For example, an equatorward shift in the winds, though its affect on the Southern Ocean circulation, has been suggested as the leading cause for the reduction in atmospheric CO2 during the Last Glacial period. Despite the importance of the winds, it is currently not clear, from observations or model results, how they behave during the Last Glacial. Here, an atmospheric modelling study is performed to help determine likely changes in the SH westerly winds during the Last Glacial Maximum (LGM). Using LGM boundary conditions, the maximum in SH westerlies is strengthened by similar to+1 m s(-1) and moved southward by similar to 2 degrees at the 850 hPa pressure level. Boundary layer stabilisation effects over equatorward extended LGM sea-ice can lead to a small apparent equatorward shift in the wind band at the surface. Further sensitivity analysis with individual boundary condition changes indicate that changes in sea surface temperatures are the strongest factor behind the wind change. The HadAM3 atmospheric simulations, along with published PMIP2 coupled climate model simulations, are then assessed against the newly synthesised database of moisture observations for the LGM. Although the moisture data is the most commonly cited evidence in support of a large equatorward shift in the SH winds during the LGM, none of the models that produce realistic LGM precipitation changes show such a large equatorward shift. In fact, the model which best simulates the moisture proxy data is the HadAM3 LGM simulation which shows a small poleward wind shift. While we cannot prove here that a large equatorward shift would not be able to reproduce the moisture data as well, we show that the moisture proxies do not provide an observational evidence base for it.
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| 7. |
- Barker, Philip A., et al.
(författare)
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Carbon cycling within an East African lake revealed by the carbon isotope composition of diatom silica: a 25-ka record from Lake Challa, Mt. Kilimanjaro
- 2013
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 66, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- The carbon cycle of a lake is a balance between supply from the atmosphere and catchment, and the net demand exerted by primary producers, minus losses back to the atmosphere and to sediment storage. Evaluating the sum of these processes and reconstructing them from sediment records of lake history requires a range of methods and a multi-proxy approach. One promising technique is to explore the carbon-isotope composition (delta C-13(diatom)) of organic matter incorporated within the silica frustules of diatom algae. Here we present a 25,000-year record of delta C-13(diatom) from the sediments of crater Lake Challa on the eastern flank of Mt. Kilimanjaro, and along with other proxy data we make inferences about the three major phases in the history of the lake's carbon cycle. From 25 ka to 15.8 ka years BP, delta C-13(diatom) is positively correlated with the delta C-13 of bulk sediment organic matter (delta C-13(bulk)), indicating that high diatom productivity, as recorded by high % biogenic silica at this time, was preferentially removing C-12 and enriching the delta C-13 of lake-water dissolved inorganic carbon. From 15.8 to 5.5 ka the correlation between delta C-13(diatom) and delta C-13(bulk) breaks down, suggesting carbon supply to the lake satisfied or exceeded the demand from productivity. From 5.5 ka BP the positive correlation resumes, indicating an increase in the internal demand for carbon relative to external supply. Diatom frustule-bound carbon isotopes offer an original tool in examining long-term fluctuations in a lake's carbon budget and how the balance between supply and demand has changed through time. (C) 2012 Elsevier Ltd. All rights reserved.
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| 8. |
- Gardner, M., et al.
(författare)
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Crustal differentiation processes at Krakatau volcano, Indonesia
- 2013
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Ingår i: Journal of Petrology. - : Oxford University Press (OUP). - 0022-3530 .- 1460-2415. ; 54:1, s. 149-182
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Tidskriftsartikel (refereegranskat)abstract
- Anak Krakatau is a basaltic andesite cone that has grown following the famous caldera-forming 1883 eruption of Krakatau. It breached sea level in 1927 and since the 1950s has been growing at an average rate of similar to 8 cm a week. We present new major and trace element data combined with whole-rock delta O-18, Sr and Nd isotope data for 1883, 1993 and 2002 Krakatau eruptive products and the surrounding crust. Bombs erupted from Anak Krakatau during 2002 contain frothy metasedimentary and plutonic xenoliths that show variable degrees of thermal metamorphism, plastic deformation and partial melting. Contact-metamorphic minerals such as cordierite and tridymite in metasedimentary xenoliths are consistent with high-temperature metamorphism and incorporation at mid- to upper-crustal depth. Energy-constrained assimilation and fractional crystallization modelling of whole-rock data suggests that the Anak Krakatau magmas have a genetic relationship with the 1883 eruption products. The geochemical impact of crustal contaminants on whole-rock compositions is apparently small, and we conclude that low levels of assimilation of a quartzo-feldspathic sediment are recorded in Anak Krakatau magmas. Plagioclase phenocrysts from the 2002 eruption exhibit disequilibrium textures and complex compositional zoning, however, and are also isotopically variable with a total range in Sr-87/Sr-86 of 0 center dot 7043-0 center dot 7048 as determined by in situ laser ablation inductively coupled plasma mass spectrometry. This suggests that although shallow crustal assimilation appears to have had a limited effect on whole-rock chemistry, a complex late-stage differentiation history is recorded within the magma's cargo of crystals and xenoliths.
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| 9. |
- Lind, Monica P., et al.
(författare)
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Circulating levels of persistent organic pollutants are related to retrospective assessment of life-time weight change
- 2013
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 90:3, s. 998-1004
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Tidskriftsartikel (refereegranskat)abstract
- Background: Persistent organic pollutants (POPs) have been suggested to be linked to obesity. We have previously shown that less-chlorinated PCBs were positively related to fat mass, while highly-chlorinated PCBs were inversely related to obesity.Objective: The aim of the present evaluation is to investigate the relationship between retrospective assessed life-time change in body weight (20-70. years) with circulating POP levels measured at age 70. years.Methods: 1016 subjects aged 70. years were investigated in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUSs) study. 16 PCBs and 3 OC pesticides were analyzed using HRGC/HRMS. Current body weight was measured and participants self-reported their weight at age 20.Results: The average estimated weight change over 50. years was 14.4. kg. Both the sum of OC pesticide concentrations (4.3. kg more weight gain in quintile 5 vs. quintile 1, p< 0.0001) and the sum of the less-chlorinated PCBs were positively related to the estimated weight change (3.7. kg more weight gain in quintile 2 vs. quintile 1, non-linear relationship p=0.0015). In contrast, the sum of concentrations of highly-chlorinated PCBs were inversely related to estimated weight change (8.4. kg less weight gain in quintile 5 vs. quintile 1, p< 0.0001).Conclusion: High levels of OC pesticides and the less-chlorinated PCBs at age 70 were associated with a pronounced estimated weight change over the previous 50. years. However, the opposite was seen for highly-chlorinated PCBs. Differences in mode of action, toxicokinetics, non-linear relationships and reverse causation might explain these discrepancies.
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| 10. |
- Markkula, Gustav M, 1978, et al.
(författare)
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Effects of experience and electronic stability control on low friction collision avoidance in a truck driving simulator
- 2013
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 50, s. 1266-1277
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Tidskriftsartikel (refereegranskat)abstract
- Two experiments were carried out in a moving-base simulator, in which truck drivers of varying experience levels encountered a rear-end collision scenario on a low-friction road surface, with and without an electronic stability control (ESC) system. In the first experiment, the drivers experienced one instance of the rear-end scenario unexpectedly, and then several instances of a version of the scenario adapted for repeated collision avoidance. In the second experiment, the unexpected rear-end scenario concluded a stretch of driving otherwise unrelated to the study presented here. Across both experiments, novice drivers were found to collide more often than experienced drivers in the unexpected scenario. This result was found to be attributable mainly to longer steering reaction times of the novice drivers, possibly caused by lower expectancy for steering avoidance. The paradigm for repeated collision avoidance was able to reproduce the type of steering avoidance situation for which critical losses of control were observed in the unexpected scenario and, here, ESC was found to reliably reduce skidding and control loss. However, it remains unclear to what extent the results regarding ESC benefits in repeated avoidance are generalisable to unexpected situations. The approach of collecting data by appending one unexpected scenario to the end of an otherwise unrelated experiment was found useful, albeit with some caveats.
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