50 research outputs found
Statistical Analysis of High-Flow Traffic States
The relation between the fundamental observables of traffic flow (i.e.,
vehicle density, flow rate, and average velocity) is of great importance for
the study of traffic phenomena. Probably the most common source of such data
are inductive loop detectors, which count the number of passing vehicles and
measure their speed. We will present an analysis of detector data collected by
more than 3000 loop detectors during the past three years on the motorway
network of the state of North Rhine-Westphalia. Besides presenting some general
aspects of traffic flow, our analysis focuses on the characteristics of
so-called high-flow states, i.e. traffic states where the flow rate exceeds 50
vehicles per minute and lane (3000 veh/h/lane). We investigate the duration,
frequency and other statistics of such states, the viability of the data and we
study the conditions under which they occur. The factors that influence the
existence of high-flow states in traffic are, for instance, the fraction of
slow vehicles (namely trucks), the motorway's general topology (e.g. number of
lanes), the hour of the day and day of the week. This information is directly
accessible from the detector data.Comment: 6 pages, 4 figures, presented at "Traffic and Granular Flow 2013"
conferenc
Extending time-domain ptychography to generalized phase-only transfer functions
We extend the time-domain ptychographic iterative engine to generalized
spectral phase-only transfer functions. The modified algorithm, iPIE, is
described and its robustness is demonstrated by different numeric simulations.
The concept is experimentally verified by reconstruction of a complex
supercontinuum pulse from an all normal dispersion fiber.Comment: 5 pages, 4 figures, submitted to Optic
Time-domain ptychography
Through dedicated measurements in the optical regime we demonstrate that
ptychography can be applied to reconstruct complex-valued object functions that
vary with time from a sequence of spectral measurements. A probe pulse of
approximately 1 ps duration, time delayed in increments of 0.25 ps is shown to
recover dynamics on a ten times faster time scale with an experimental limit of
approximately 5 fs.Comment: 5 pages, 4 figures, new title and minor text change
A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar
The cambial meristem is responsible for bark and wood formation in woody plants. The activity of the cambial meristem is controlled by various factors; one of them is the plant hormone cytokinin. Here, we have explored different approaches to genetically engineering cambial activity in poplar plants by the ectopic expression of a cytokinin biosynthesis gene with enhanced activity (named ROCK4) or of a gene encoding a constitutively active cytokinin receptor variant (ROCK3). Both genes are derived from Arabidopsis thaliana and were expressed in poplar trees under the control of their own promoter or the cambium-specific pHB8 promoter. pIPT3:ROCK4- and pHB8:ROCK4-expressing plants were smaller than wild-type plants and formed more lateral branches; pHB8:ROCK4 transgenic plants additionally showed an increased stem diameter. In contrast, pAHK3:ROCK3- and pHB8:ROCK3-expressing plants grew taller than wild type without an altered branching pattern and formed more cambial cells, leading to increased radial stem growth. The effectivity of ROCK3 when expressed in either secondary phloem cells or in cambial cells is consistent with a dual, tissue-autonomous and non-autonomous activity of cytokinin in regulating cambial activity. We propose ROCK3 as a novel gene to enhance biomass formation in woody plants
Comparative theoretical analysis of continuous wave laser cutting of metals at 1 and 10μm wavelength
We present a derivation and, based on it, an extension of a model originally proposed by V.G. Niziev to describe continuous wave laser cutting of metals. Starting from a local energy balance and by incorporating heat removal through heat conduction to the bulk material, we find a differential equation for the cutting profile. This equation is solved numerically and yields, besides the cutting profiles, the maximum cutting speed, the absorptivity profiles, and other relevant quantities. Our main goal is to demonstrate the model's capability to explain some of the experimentally observed differences between laser cutting at around 1 and 10μm wavelengths. To compare our numerical results to experimental observations, we perform simulations for exactly the same material and laser beam parameters as those used in a recent comparative experimental study. Generally, we find good agreement between theoretical and experimental results and show that the main differences between laser cutting with 1- and 10-μm beams arise from the different absorptivity profiles and absorbed intensities. Especially the latter suggests that the energy transfer, and thus the laser cutting process, is more efficient in the case of laser cutting with 1-μm beams
From Stable to Lab—Investigating Key Factors for Sudden Deaths Caused by Streptococcus suis
Swine stocks are endemically infected with the major porcine pathogen Streptococcus (S.)
suis. The factors governing the transition from colonizing S. suis residing in the tonsils and the
exacerbation of disease have not yet been elucidated. We analyzed the sudden death of fattening
pigs kept under extensive husbandry conditions in a zoo. The animals died suddenly of septic shock
and showed disseminated intravascular coagulopathy. Genotypic and phenotypic characterizations
of the isolated S. suis strains, a tonsillar isolate and an invasive cps type 2 strain, were conducted.
Isolated S. suis from dead pigs belonged to cps type 2 strain ST28, whereas one tonsillar S. suis
isolate harvested from a healthy animal belonged to ST1173. Neither S. suis growth, induction of
neutrophil extracellular traps, nor survival in blood could explain the sudden deaths. Reconstituted
blood assays with serum samples from pigs of different age groups from the zoo stock suggested
varying protection of individuals against pathogenic cps type 2 strains especially in younger pigs.
These findings highlight the benefit of further characterization of the causative strains in each case by
sequence typing before autologous vaccine candidate selection
Gauge conditions for long-term numerical black hole evolutions without excision
Numerical relativity has faced the problem that standard 3+1 simulations of
black hole spacetimes without singularity excision and with singularity
avoiding lapse and vanishing shift fail after an evolution time of around
30-40M due to the so-called slice stretching. We discuss lapse and shift
conditions for the non-excision case that effectively cure slice stretching and
allow run times of 1000M and more.Comment: 19 pages, 14 figures, REVTeX, Added a missing Acknowledgmen
The Samurai Project: verifying the consistency of black-hole-binary waveforms for gravitational-wave detection
We quantify the consistency of numerical-relativity black-hole-binary
waveforms for use in gravitational-wave (GW) searches with current and planned
ground-based detectors. We compare previously published results for the
mode of the gravitational waves from an equal-mass
nonspinning binary, calculated by five numerical codes. We focus on the 1000M
(about six orbits, or 12 GW cycles) before the peak of the GW amplitude and the
subsequent ringdown. We find that the phase and amplitude agree within each
code's uncertainty estimates. The mismatch between the modes
is better than for binary masses above with respect to
the Enhanced LIGO detector noise curve, and for masses above
with respect to Advanced LIGO, Virgo and Advanced Virgo. Between the waveforms
with the best agreement, the mismatch is below . We find that
the waveforms would be indistinguishable in all ground-based detectors (and for
the masses we consider) if detected with a signal-to-noise ratio of less than
, or less than in the best cases.Comment: 17 pages, 9 figures. Version accepted by PR
Examination of macro- and microelements distribution between total extract and fractions for nootropic plant-derived raw material Alfredia cernua
The paper dwells on a quantitative determination of macro- and microelements in the ethanol Alfredia cernua extract and its chloroform, ethyl acetate, and butanol fractions. The distribution of macro- and microelements in the extract and fractions was investigated to further study of the interrelation between chemical composition and nootropic activity Alfredia cernua. It is shown that B, Fe, and Sn is mainly accumulated in butanol and Si, P, Al - in chloroform fraction respectively, but most macro- and microelements remain in the ethanol extract
Error-analysis and comparison to analytical models of numerical waveforms produced by the NRAR Collaboration
The Numerical-Relativity-Analytical-Relativity (NRAR) collaboration is a
joint effort between members of the numerical relativity, analytical relativity
and gravitational-wave data analysis communities. The goal of the NRAR
collaboration is to produce numerical-relativity simulations of compact
binaries and use them to develop accurate analytical templates for the
LIGO/Virgo Collaboration to use in detecting gravitational-wave signals and
extracting astrophysical information from them. We describe the results of the
first stage of the NRAR project, which focused on producing an initial set of
numerical waveforms from binary black holes with moderate mass ratios and
spins, as well as one non-spinning binary configuration which has a mass ratio
of 10. All of the numerical waveforms are analysed in a uniform and consistent
manner, with numerical errors evaluated using an analysis code created by
members of the NRAR collaboration. We compare previously-calibrated,
non-precessing analytical waveforms, notably the effective-one-body (EOB) and
phenomenological template families, to the newly-produced numerical waveforms.
We find that when the binary's total mass is ~100-200 solar masses, current EOB
and phenomenological models of spinning, non-precessing binary waveforms have
overlaps above 99% (for advanced LIGO) with all of the non-precessing-binary
numerical waveforms with mass ratios <= 4, when maximizing over binary
parameters. This implies that the loss of event rate due to modelling error is
below 3%. Moreover, the non-spinning EOB waveforms previously calibrated to
five non-spinning waveforms with mass ratio smaller than 6 have overlaps above
99.7% with the numerical waveform with a mass ratio of 10, without even
maximizing on the binary parameters.Comment: 51 pages, 10 figures; published versio