2,033 research outputs found
Effects of anticipatory driving in a traffic flow model
Anticipation in traffic means that drivers estimate their leaders' velocities
for future timesteps. In the article a specific stochastic car--following model
with non--unique flow--density relation is investigated with respect to
anticipatory driving. It is realized by next--nearest--neighbour interaction
which leads to large flows and short temporal headways. The underlying
mechanism that causes these effects is explained by the headways of the cars
which organize in an alternating structure with a short headway following a
long one, thereby producing a strong anti-correlation in the gaps or in the
headways of subsequent cars. For the investigated model the corresponding time
headway distributions display the short headways observed in reality. Even
though these effects are discussed for a specific model, the mechanism
described is in general present in any traffic flow models that work with
anticipation.Comment: 8 pages, 11 figure
Boundary-induced phase transitions in a space-continuous traffic model with non-unique flow-density relation
The Krauss-model is a stochastic model for traffic flow which is continuous
in space. For periodic boundary conditions it is well understood and known to
display a non-unique flow-density relation (fundamental diagram) for certain
densities. In many applications, however, the behaviour under open boundary
conditions plays a crucial role.In contrast to all models investigated so far,
the high flow states of the Krauss-model are not metastable, but also stable.
Nevertheless we find that the current in open systems obeys an extremal
principle introduced for the case of simpler discrete models. The phase diagram
of the open system will be completely determined by the fundamental diagram of
the periodic system through this principle. In order to allow the investigation
of the whole state space of the Krauss-model, appropriate strategies for the
injection of cars into the system are needed.Two methods solving this problem
are discussed and the boundary-induced phase transitions for both methods are
studied.We also suggest a supplementary rule for the extremal principle to
account for cases where not all the possible bulk states are generated by the
chosen boundary conditions.Comment: 12 Pages, 14 figure
Integration von dynamischer Verkehrssimulation und Wirkungsanalyse fur die Entwicklung ressourcenschonender Verkehrsmanagement-Strategien
Um zu verhindern, dass die Nutzung von Telematik zu unerwün-schten negativen Effekten führt, müssen Verkehrsmanagement-Strategien jenseits der üblichen nutzeroptimalen Lösungen entwickelt werden. Mit diesem Ziel werden in dieser Arbeit dynamische Verkehrssimulationsmodelle und verfeinerte Prognose- und Auswertungsmodelle gekoppelt, mit denen Strategien hinsichtlich ihrer Umweltwirkungen und wirtschaftlichen Effizienz bewertet werden können. Hierfür stehen dynamische, mikroskopische Verkehrsmodelle zur Verfügung, die im Rahmen des stadtinfoköln -Projektes zu Prognoseinstrumenten weiter entwickelt werden. Als Ergebnis der Integration dieser Modelle mit Modellen zur strategischen Prognose und Bewertung von Verkehrswirkungen lassen sich erste Bandbreiten für die Wirksamkeit und Effizienz einzelner Verkehrsmanagement-Maßnahmen abschätzen. Gleichzeitig wird die Notwendigkeit zur Verfeinerung der Umweltmodelle deutlich, um den dynamischen Aspekten des Verkehrsablaufes Rechnung zu tragen. Daher werden Modelle zur Emissionsprognose im Straßenverkehr weiterentwickelt und mit vorhande-nen Simulationsmodellen (PELOPS) abgestimmt, welche die Fahrdynamik der Fahrzeuge berücksichtigen. Auf Basis der Ergebnisse werden erste Szenarien für Management-Strategien gezielt so entwickelt, dass vorgegebene Umwelt- und Sicherheitsziele erreicht und Wirtschaftlichkeitskriterien maximiert werden. Mittelfristig ist das Ziel, intelligente Entscheidungsunterstützungssysteme aufzubauen, die Verkehrsmanagern bei aus gemessenen Verkehrsdaten rekonstruierten realen Verkehrssituationen effiziente, ressourcensparende Lösungen von Verkehrsproblemen offerieren
The between-person and within-person effects of intergroup contact on outgroup attitudes: a multi-context examination
The extensive literature on the contact hypothesis reports a positive association between intergroup contact and outgroup attitudes, yet it remains unknown whether this association reflects within-person (i.e., situational changes within individuals) or between-person (i.e., stable differences between individuals) effects. To investigate this question, we applied (random-intercept) cross-lagged panel models in two studies featuring different samples, measurements, and contexts. We found longitudinal contact–attitude associations in cross-lagged panel models, which cannot differentiate within-person and between-person effects. In random-intercept cross-lagged panel models, we identified between-person effects but not within-person effects. These results conflict with the contact hypothesis, which assumes that contact leads to intra-individual attitude change. We further investigated whether between-person effects represent spurious correlations caused by potential confounders (demographic characteristics, personality, and intergroup ideologies), but found that this was not the case. Our findings highlight the need to further investigate within-person effects and potential explanations of between-person differences in contact and attitudes
Removing fluoride-terminations from multilayered V2CTx MXene by gas hydrolyzation
Two-dimensional MXenes have shown great promise for many different applications, but in order to fully utilize their potential, control of their termination groups is essential. Here we demonstrate hydrolyzation with a continuous gas flow as a method to remove F-terminations from multilayered V2CTx particles, in order to prepare nearly F-free and partly bare vanadium carbide MXene. Density functional theory calculations demonstrate that the substitution of F-terminations is thermodynamically feasible and presents partly nonterminated V2CO as the dominating hydrolyzation product. Hydrolyzation at elevated temperatures reduced the F content but only subtly changed the O content, as inferred from spectroscopic data. The ideal hydrolyzation temperature was found to be 300 °C, as a degradation of the V2CTx phase and a transition to vanadium oxycarbides and V2O3 were observed at higher temperature. When tested as electrodes in Li-ion batteries, the hydrolyzed MXene demonstrated a reduced polarization compared with the pristine MXene, but no change in intercalation voltage was observed. Annealing in dry Ar did not result in the same F reduction, and the importance of water vapor was concluded, demonstrating hydrolyzation as a new and efficient method to control the surface terminations of multilayered V2CTx post etching. These results also provide new insights on the thermal stability of V2CTx MXene in hydrated atmospheres.publishedVersio
Correction : Welter et al. Characteristics of Nephroblastoma/Nephroblastomatosis in Children with a Clinically Reported Underlying Malformation or Cancer Predisposition Syndrome. Cancers 2021, 13, 5016
In the original article [1] there was a mistake in Table 2 as published. Table 2 contains
wrong percentages in lines Bilateral disease and Patients with CPS or GU. For this reason the
table should be replaced with the correct one as shown belo
Characteristics of Nephroblastoma/Nephroblastomatosis in Children with a Clinically Reported Underlying Malformation or Cancer Predisposition Syndrome
(1) Background: about 10% of Wilms Tumor (WT) patients have a malformation or cancer
predisposition syndrome (CPS) with causative germline genetic or epigenetic variants. Knowledge
on CPS is essential for genetic counselling. (2) Methods: this retrospective analysis focused on
2927 consecutive patients with WTs registered between 1989 and 2017 in the SIOP/GPOH studies.
(3) Results: Genitourinary malformations (GU, N = 66, 2.3%), Beckwith-Wiedemann spectrum
(BWS, N = 32, 1.1%), isolated hemihypertrophy (IHH, N = 29, 1.0%), Denys-Drash syndrome (DDS,
N = 24, 0.8%) and WAGR syndrome (N = 20, 0.7%) were reported most frequently. Compared to
others, these patients were younger at WT diagnosis (median age 24.5 months vs. 39.0 months),
had smaller tumors (349.4 mL vs. 487.5 mL), less often metastasis (8.2% vs. 18%), but more often
nephroblastomatosis (12.9% vs. 1.9%). WT with IHH was associated with blastemal WT and DDS
with stromal subtype. Bilateral WTs were common in WAGR (30%), DDS (29%) and BWS (31%).
Chemotherapy induced reduction in tumor volume was poor in DDS (0.4% increase) and favorable
in BWS (86.9% reduction). The event-free survival (EFS) of patients with BWS was significantly
(p = 0.002) worse than in others. (4) Conclusions: CPS should be considered in WTs with specific
clinical features resulting in referral to a geneticist. Their outcome was not always favorable
Nitric oxide-independent vasodilator rescues heme-oxidized soluble guanylate cyclase from proteosomal degradation
Background: Nitric oxide (NO) is an essential vasodilator. In vascular diseases, oxidative stress attenuates NO signaling by both chemical scavenging of free NO and oxidation and down-regulation of its major intracellular receptor, the alpha/beta heterodimeric heme-containing soluble guanylate cyclase (sGC). Oxidation can also induce loss of sGC's heme and responsiveness to NO.
Results: sGC activators such as BAY 58-2667 bind to oxidized/heme-free sGC and reactivate the enzyme to exert disease-specific vasodilation. Here we show that oxidation-induced down-regulation of sGC protein extends to isolated blood vessels. Mechanistically, degradation was triggered through sGC ubiquitination and proteasomal degradation. The heme-binding site ligand, BAY 58-2667, prevented sGC ubiquitination and stabilized both alpha and beta subunits.
Conclusion: Collectively, our data establish oxidation-ubiquitination of sGC as a modulator of NO/cGMP signaling and point to a new mechanism of action for sGC activating vasodilators by stabilizing their receptor, oxidized/heme-free sGC
The track finding algorithm of the Belle II vertex detectors
The Belle II experiment is a high energy multi purpose particle detector operated at the asymmetric e+e-- collier SuperKEKB in Tsukuba (Japan). In this work we describe the algorithm performing the pattern recognition for inner tracking detector which consists of two layers of pixel detectors and four layers of double sided silicon strip detectors arranged around the interaction region. The track finding algorithm will be used both during the High Level Trigger on-line track reconstruction and during the off-line full reconstruction. It must provide good efficiency down to momenta as low as 50 MeV/c where material effects are sizeable even in an extremely thin detector as the VXD. In addition it has to be able to cope with the high occupancy of the Belle II detectors due to the background. The underlying concept of the track finding algorithm, as well as details of the implementation are outlined. The algorithm is proven to run with good performance on simulated Y (4S) â\u86\u92 BB events with an efficiency for reconstructing tracks of above 90% over a wide range of momentum
- …