1,179 research outputs found
Optimisation of Signal Timing at Intersections with Waiting Areas
Unconventional geometric designs such as continu-ous-flow intersections, U-turns, and contraflow left-turn lanes have been proposed to reduce left-turn conflicts and improve intersection efficiency. Having a waiting area at a signalised intersection is an unconventional de-sign that is used widely in China and Japan to improve traffic capacity. Many studies have shown that waiting areas improve traffic capacity greatly, but few have con-sidered how to improve the benefits of this design from the aspect of signal optimisation. Comparing the start-up process of intersections with and without waiting areas, this work explores how this geometric design influenc-es vehicle transit time, proposes two signal optimisation strategies, and establishes a unified capacity calculation model. Taking capacity maximisation as the optimisation function, a cycle optimisation model is derived for over-saturated intersections. Finally, the relationship among waiting-area storage capacity, cycle time, and traffic ca-pacity is discussed using field survey data. The results of two cases show that optimising the signal scheme helps reduce intersection delays by 10–15%
On the Formation of Double Neutron Stars in the Milky Way: Influence of Key Parameters
The detection of gravitational wave events has stimulated theoretical
modeling of the formation and evolution of double compact objects (DCOs).
However, even for the most studied isolated binary evolution channel, there
exist large uncertainties in the input parameters and treatments of the binary
evolution process. So far, double neutron stars (DNSs) are the only DCOs for
which direct observations are available through traditional electromagnetic
astronomy. In this work, we adopt a population synthesis method to investigate
the formation and evolution of Galactic DNSs. We construct 324 models for the
formation of Galactic DNSs, taking into account various possible combinations
of critical input parameters and processes such as mass transfer efficiency,
supernova type, common envelope efficiency, neutron star kick velocity, and
pulsar selection effect. We employ Bayesian analysis to evaluate the adopted
models by comparing with observations. We also compare the expected DNS merger
rate in the Galaxy with that inferred from the known Galactic population of
Pulsar-NS systems. Based on these analyses we derive favorable range of the
aforementioned key parameters.Comment: 29 pages, 9 figures, 2 tables, accepted by Ap
Construction and characterization of a cDNA library from human brain glioma cell line U251 with overexpressed exogenous p53 gene
The tumor-suppressor gene p53 and its downstream genes consist of a complicated gene network, and the challenge to understand the network is to identify p53 downstream genes. In order to isolate and identify new p53 regulated genes, we constructed and characterized a normalized cDNA library from human brain glioma cell line U251 while exogenous p53 gene is overexpressed. The constructed cDNA library contained 1.3×106 directional recombinants, and its insert size ranged from 0.5 to 2.0 kb. Screening the cDNA library, we obtained two novel p53 downstream genes, PAP1 and PAP2. Polymerase chain reaction (PCR) analyses of the library for specific genes revealed the presence of cDNAs for p53 downstream genes such as p21, gadd45, and PCNA. These results demonstrate the sequence complexity and relatively low redundancy of our cDNA library. It is a valuable and unique resource for studying p53 gene expression, regulatory mechanisms and screening p53 downstream genes. Keywords: p53 Gene, p53 downstream gene, cDNA library, normalizationAfrican Journal of Biotechnology Vol. 9(33), pp. 5262-5268, 16 August, 201
Tetrakis(μ-benzoato-κ2 O:O′)bis{[4-(dimethylamino)pyridine-κN 1]zinc(II)}
In the centrosymmetric binuclear title complex, [Zn2(C7H5O2)4(C7H10N2)2], the Zn atoms [Zn⋯Zn = 3.0037 (6) Å] are bridged by four benzoate ligands. Each of the Zn atoms assumes an approximately square-pyramidal environment, with four O atoms in a plane and the pyridine N atom at the apical site
Advancements in Sensor Technologies and Control Strategies for Lower-Limb Rehabilitation Exoskeletons: A Comprehensive Review
Lower-limb rehabilitation exoskeletons offer a transformative approach to enhancing recovery in patients with movement disorders affecting the lower extremities. This comprehensive systematic review delves into the literature on sensor technologies and the control strategies integrated into these exoskeletons, evaluating their capacity to address user needs and scrutinizing their structural designs regarding sensor distribution as well as control algorithms. The review examines various sensing modalities, including electromyography (EMG), force, displacement, and other innovative sensor types, employed in these devices to facilitate accurate and responsive motion control. Furthermore, the review explores the strengths and limitations of a diverse array of lower-limb rehabilitation-exoskeleton designs, highlighting areas of improvement and potential avenues for further development. In addition, the review investigates the latest control algorithms and analysis methods that have been utilized in conjunction with these sensor systems to optimize exoskeleton performance and ensure safe and effective user interactions. By building a deeper understanding of the diverse sensor technologies and monitoring systems, this review aims to contribute to the ongoing advancement of lower-limb rehabilitation exoskeletons, ultimately improving the quality of life for patients with mobility impairments
Comparative study of gamma-ray emission from molecular clouds and star-forming galaxies
Star-forming regions on different scales, such as giant molecular clouds in
our Galaxy and star-forming galaxies, emit GeV gamma-rays. These are thought to
originate from hadronic interactions of cosmic-ray (CR) nuclei with the
interstellar medium. It has recently been shown that the gamma-ray luminosity
() of star-forming galaxies is well correlated with their star
formation rates (SFR). We investigated \textsl{Fermi} data of eight Galactic
molecular clouds in the Gould belt and found that molecular clouds do not
follow the correlation of star-forming galaxies. We also
compared the scaling relations of gamma-ray luminosity, SFR, and the gas mass
for molecular clouds and star-forming galaxies. Using a multiple-variable
regression analysis, we found different dependences of gamma-ray emission on
SFR or mass for molecular clouds and star-forming galaxies. This suggests that
different mechanisms may govern the production of gamma-rays in these two types
of sources. Specifically, the strong dependence on mass supports that gamma-ray
emission of molecular clouds primarily comes from {\em \textup{passive}}
interaction by diffuse Galactic CRs, whereas the strong dependence on SFR
supports that gamma-ray emission of star-forming galaxies originates from CRs
that are accelerated by local {\em \textup{active}} sources.Comment: Accepted for publication in Astronomy & Astrophysic
Features of the gamma-ray pulsar halo HESS J1831098
Gamma-ray pulsar halos are ideal indicators of cosmic-ray propagation in
localized regions of the Galaxy and electron injection from pulsar wind
nebulae. HESS~J1831098 is a candidate pulsar halo observed by both H.E.S.S.
and HAWC experiments. We adopt the flux map of the H.E.S.S. Galactic plane
survey and the spectrum measurements of H.E.S.S. and \textit{Fermi}-LAT to
study HESS~J1831098. We find that HESS~J1831098 meets all the criteria
for a pulsar halo. The diffusion coefficient inside the halo and the conversion
efficiency from the pulsar spin-down energy to the electron energy are both
similar to the Geminga halo, a canonical pulsar halo. The injection spectrum
can be well described by an exponentially-cutoff power law. However, the needed
power-law term is very hard with if the diffusion coefficient is
spatially and temporally independent. Considering the possible origins of the
slow-diffusion environment, we adopt the two-zone diffusion model and the
time-delayed slow-diffusion model. Both the models can interpret the H.E.S.S.
and \textit{Fermi}-LAT results with a milder . A modified injection time
profile may have a similar effect.Comment: 15 pages (one column), 4 figures, 1 tabl
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