2,247 research outputs found
Internal Kinematics of Distant Field Galaxies: I. Emission Line Widths for a Complete Sample of Faint Blue Galaxies at <z>=0.25
We present measurements of the OII(3727) emission line width for a complete
sample of 24 blue field galaxies (21.25=0.25, obtained
with the AUTOFIB fibre spectrograph on the Anglo-Australian Telescope. Most
emission lines are spectrally resolved, yet all have dispersions sigma<100km/s.
Five of the 24 sample members have OII doublet line flux ratios which imply gas
densities in excess of 100 cm^-3. The line emission in these galaxies may be
dominated by an active nucleus and the galaxies have been eliminated from the
subsequent analysis. The remaining 19 linewidths are too large by a factor of
two (7sigma significance) to be attributed to turbulent motions within an
individual star forming region, and therefore most likely reflect the orbital
motion of ionized gas in the galaxy. We use Fabry--Perot observations of nearby
galaxies to construct simulated datasets that mimic our observational setup at
z=0.25; these allow us to compute the expected distribution of (observable)
linewidths sigma_v for a galaxy of a given ``true'' (optical) rotation speed
v_c. These simulations include the effects of random viewing angles, clumpy
line emission, finite fibre aperture, and internal dust extinction on the
emission line profile. We assume a linewidth--luminosity--colour relation: ln[
v_c(M_B,B-R) ] = ln[v_c(-19,1)] - eta*(M_B+10) + zeta*[(B-R)-1] and determine
the range of parameters consistent with our data. We find a mean rotation speed
of v_c(-19,1)=66+-8km/s (68% confidence limits) for the distant galaxies with
M_B=-19 and B-R=1, with a magnitude dependence for v_c of eta=0.07+-0.08, and a
colour dependence of zeta =0.28+-0.25. Through comparison with several local
samples we show that this value of v_c(-19,1) is significantly lower than the
optical rotation speed of present-day galaxies with the same absolute magnitudeComment: TeX Text and Tables, no Figures. Compressed and uuencoded PS file of
the complete paper (43 pages including 9 figures) available at
http://zwicky.as.arizona.edu/~rix/; submitted to MNRA
Cultivation and analysis of anthocyanins containing-, blue potatoes
Anthocyanins, as secondary plant substance in different agricultural crops such as potatoes and cereals have positive effects on health due to their antioxidant capacity. Therefore food industry, nutritional medicine and consumers have an increasing interest in these crops. The objectives of the interdisciplinary research project (AGIP) starting in march 2006 are ascertainment and assessment of the impact of different agricultural production processes and production intensities. Furthermore, the impact of different ways of food preparation concerning anthocyanin content and antioxidative capacity in selected cultivated plants will be tested. Main focus will be on potatoes due to the fact that potatoes as a staple food are consumed in large quantities. Therefore potatoes can be an important quantitative source for anthocyanins
Investigation of a Second Exhaust Valve Lift to Improve Combustion in a Methane - Diesel Dual-Fuel Engine
In recent years, the utilization of dual-fuel combustion has gained
popularity in order to improve engine efficiency and emissions. With
its high knock resistance, methane allows operation in high
compression diesel engines with lower risk of knocking. With the use
of diesel fuel as an ignition source, it is possible to exploit the
advantages of lean combustion without facing problems to provide
the high amount of ignition energy necessary to burn methane under
such operating conditions. Another advantage is the variety of
sources from which the primary fuel can be obtained. In addition to
fossil sources, methane can also be produced from biomass or
electrical energy.
As the rate of substitution of diesel by methane increases, the trade-
off between nitrogen oxide and soot is mitigated. However, emissions
of carbon monoxide and unburned methane increase. Since carbon
monoxide is toxic and methane has 25 times the global warming
potential of carbon dioxide, these emission components pose a
problem. Because of the stability of the molecule, methane catalysts
require an exhaust gas temperature of over 500 °C in order to work
effectively.
In this work, the effect of conventional cooled external exhaust gas
recirculation (EGR) and additional hot internal EGR are investigated
for different substitution rates in a nonroad tractor engine converted
to dual-fuel operation. The internal EGR rate is controlled by a
variable second exhaust valve lift during the intake stroke â an
approach which promises to benefit dual-fuel engines by increasing
the in-cylinder gas temperature, thus favoring more complete
combustion. A simulation model of the engine is used to determine
the internal EGR rates and in-cylinder temperatures based on the
experimental data. When internal EGR is used in combination with
external EGR, the resulting emissions show additional reductions in
nitrogen oxide (up to -51 %), carbon monoxide (up to -18 %) and
methane (up to -28 %) with increasing internal EGR, while still
maintaining low soot levels due to the substitution of diesel fuel for
methane
Consolidation of complex events via reinstatement in posterior cingulate cortex
It is well-established that active rehearsal increases the efficacy of memory consolidation. It is also known that complex events are interpreted with reference to prior knowledge. However, comparatively little attention has been given to the neural underpinnings of these effects. In healthy adult humans, we investigated the impact of effortful, active rehearsal on memory for events by showing people several short video clips and then asking them to recall these clips, either aloud (Experiment 1) or silently while in an MRI scanner (Experiment 2). In both experiments, actively rehearsed clips were remembered in far greater detail than unrehearsed clips when tested a week later. In Experiment 1, highly similar descriptions of events were produced across retrieval trials, suggesting a degree of semanticization of the memories had taken place. In Experiment 2, spatial patterns of BOLD signal in medial temporal and posterior midline regions were correlated when encoding and rehearsing the same video. Moreover, the strength of this correlation in the posterior cingulate predicted the amount of information subsequently recalled. This is likely to reflect a strengthening of the representation of the video's content. We argue that these representations combine both new episodic information and stored semantic knowledge (or "schemas"). We therefore suggest that posterior midline structures aid consolidation by reinstating and strengthening the associations between episodic details and more generic schematic information. This leads to the creation of coherent memory representations of lifelike, complex events that are resistant to forgetting, but somewhat inflexible and semantic-like in nature
KREMLAS: Entwicklung einer kreativen evolutionĂ€ren Entwurfsmethode fĂŒr Layoutprobleme in Architektur und StĂ€dtebau
Die im vorliegenden Buch dokumentierten Untersuchungen befassen sich mit der Entwicklung von Methoden zur algorithmischen Lösung von Layoutaufgaben im architektonischen Kontext. Layout bezeichnet hier die gestalterisch und funktional sinnvolle Anordnung rĂ€umlicher Elemente, z.B. von Parzellen, GebĂ€uden, RĂ€umen auf bestimmten MaĂstabsebenen. Die vorliegenden Untersuchungen sind im Rahmen eines von der Deutschen Forschungsgemeinschaft geförderten Forschungsprojekts entstanden
- âŠ