829 research outputs found
Towards integrated powertrain control: thermal management of NG heated catalyst system
Towards Integrated Powertrain Control: Thermal Management of NG Heated Catalyst System — The conversion efficiency of catalytic converters is mainly defined by the temperature range wherein they are operating. Traditionally, ignition retard has been used to reduce the light-off time of the catalyst. This is however associated with a fuel penalty. With increasing vehicle electrification, external heating facilities present an alternative, especially for hybrid vehicles. Nevertheless, system complexity of hybrid vehicles prevents engineers to evaluate possible heating technologies with respect to traditional solutions
Anthropogenic Space Weather
Anthropogenic effects on the space environment started in the late 19th
century and reached their peak in the 1960s when high-altitude nuclear
explosions were carried out by the USA and the Soviet Union. These explosions
created artificial radiation belts near Earth that resulted in major damages to
several satellites. Another, unexpected impact of the high-altitude nuclear
tests was the electromagnetic pulse (EMP) that can have devastating effects
over a large geographic area (as large as the continental United States). Other
anthropogenic impacts on the space environment include chemical release ex-
periments, high-frequency wave heating of the ionosphere and the interaction of
VLF waves with the radiation belts. This paper reviews the fundamental physical
process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure
Freeze–thaw cycles have minimal effect on the mineralisation of low molecular weight, dissolved organic carbon in Arctic soils
Warmer winters in Arctic regions may melt
insulating snow cover and subject soils to more freeze–
thaw cycles. The effect of freeze–thaw cycles on the
microbial use of low molecular weight, dissolved organic
carbon (LMW-DOC) is poorly understood. In this study,
soils from the Arctic heath tundra, Arctic meadow tundra
and a temperate grassland were frozen to -7.5 C and
thawed once and three times. Subsequently, the mineralisation of 3 LMW-DOC substrates types (sugars, amino
acids and peptides) was measured over an 8-day period and
compared to controls which had not been frozen. This
allowed the comparison of freeze–thaw effects between
Arctic and temperate soil and between different substrates.
The results showed that freeze–thaw cycles had no significant effect on C mineralisation in the Arctic tundra
soils. In contrast, for the same intensity freeze–thaw cycles,
a significant effect on C mineralisation was observed for all
substrate types in the temperate soil although the response
was substrate specific. Peptide and amino acid mineralisation were similarly affected by FT, whilst glucose had a
different response. Further work is required to fully
understand microbial use of LMW-DOC after freeze–thaw,
yet these results suggest that relatively short freeze–thaw
cycles have little effect on microbial use of LMW-DOC in
Arctic tundra soils after thaw
The Geological Record of Ocean Acidification
Ocean acidification may have severe consequences for marine ecosystems; however, assessing its future impact is difficult because laboratory experiments and field observations are limited by their reduced ecologic complexity and sample period, respectively. In contrast, the geological record contains long-term evidence for a variety of global environmental perturbations, including ocean acidification plus their associated biotic responses. We review events exhibiting evidence for elevated atmospheric CO2, global warming, and ocean acidification over the past ~300 million years of Earth's history, some with contemporaneous extinction or evolutionary turnover among marine calcifiers. Although similarities exist, no past event perfectly parallels future projections in terms of disrupting the balance of ocean carbonate chemistry—a consequence of the unprecedented rapidity of CO2 release currently taking place
'Who Wrote 2 Thessalonians:A Fresh Look at an Old Problem'
In light of the New Perspective on Paul, recognition of apocalyptic as a central category in Pauline theology, and the crumbling consensus concerning seven authentic epistles of Paul, it is time to reconsider the arguments for the authenticity of his letters. Here the specific question of the authorship of 2 Thessalonians is re-examined. It is noted that many of the standard arguments for or against the authenticity of 2 Thessalonians are either irrelevant or inconclusive. This discussion seeks to reveal the slender evidential basis of certain ‘classic’ arguments against the authenticity of the letter, and also to present some fresh reasons why the epistle should be regarded as written by Paul. The implications of including 2 Thessalonians among the authentic Pauline writings are then examined. In particular, it is suggested that the development in Paul’s thinking as reflected in 2 Thessalonians reveals that his theological formulations developed in response to situations in his fledgling communities. In this regard, Paul’s theological positions emerged through a negotiated response to pressing pastoral situations
Entrainment of the Melatonin Rhythms in Early Postnatal Lambs and Their Mothers
Although the developing sheep can produce an appropriately timed melatonin rhythm as early as 1 week after birth, it is not known whether the lamb is able to adjust its melatonin rhythm to a change in daylength. The ability of the young lamb to entrain its pattern of melatonin secretion to a new photoperiod was determined in the present study. Eight female lambs and their mothers were raised in long days (LD 16:8) beginning 2 weeks post partum. At 7 weeks of age, the time of lights-off was advanced 8 hr, the short-day photoperiod then being LD 8:16; the time of lights-on remained unchanged. Concentrations of melatonin were measured in blood samples collected hourly on days - 1, 0, 2, 4, 6, and 13 relative to the light change. On day 0, all mothers and daughters had advanced the onset of melatonin secretion by at least 1 hr, and by day 13, 12 of 16 had completely entrained to the new photoperiod. The rate of entrainment among individuals varied; the mean rate for lambs and mothers did not differ. This study provides evidence that the melatonin-rhythm-generating system matures shortly after birth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68290/2/10.1177_074873048900400405.pd
Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
This paper reports a measurement of D*+/- meson production in jets from
proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the
CERN Large Hadron Collider. The measurement is based on a data sample recorded
with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets
with transverse momentum between 25 and 70 GeV in the pseudorapidity range
|eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay
chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate
is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for
D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z <
1. Monte Carlo predictions fail to describe the data at small values of z, and
this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table,
matches published version in Physical Review
Excitation of the Giant Resonance Region by Inelastic Scattering of Polarized Protons
This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit
Experimental Facilities Development
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
Study of the Giant Resonance Region by Inelastic Scattering of Polarized Protons
Supported by the National Science Foundation and Indiana Universit
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