1,481 research outputs found
A Two-Dimensional CA Traffic Model with Dynamic Route Choices Between Residence and Workplace
The Biham, Middleton and Levine (BML) model is extended to describe dynamic
route choices between the residence and workplace in cities. The traffic
dynamic in the city with a single workplace is studied from the velocity
diagram, arrival time probability distribution, destination arrival rate and
convergence time. The city with double workplaces is also investigated to
compared with a single workplace within the framework of four modes of urban
growth. The transitional region is found in the velocity diagrams where the
system undergoes a continuous transition from a moving phase to a completely
jamming phase. We perform a finite-size scaling analysis of the critical
density from a statistical point of view and the order parameter of this
jamming transition is estimated. It is also found that statistical properties
of urban traffic are greatly influenced by the urban area, workplace area and
urban layout.Comment: 18 pages, 13 figure
Optimal design of nonuniform FIR transmultiplexer using semi-infinite programming
This paper considers an optimum nonuniform FIR transmultiplexer design problem subject to specifications in the frequency domain. Our objective is to minimize the sum of the ripple energy for all the individual filters, subject to the specifications on amplitude and aliasing distortions, and to the passband and stopband specifications for the individual filters. This optimum nonuniform transmultiplexer design problem can be formulated as a quadratic semi-infinite programming problem. The dual parametrization algorithm is extended to this nonuniform transmultiplexer design problem. If the lengths of the filters are sufficiently long and the set of decimation integers is compatible, then a solution exists. Since the problem is formulated as a convex problem, if a solution exists, then the solution obtained is unique and the local solution is a global minimum
Scanning tunneling microscopy study of the possible topological surface states in BiTeCl
Recently, the non-centrosymmetric bismuth tellurohalides such as BiTeCl are
being studied as possible candidates of topological insulators. While some
photoemission studies showed that BiTeCl is an inversion asymmetric topological
insulator, others showed that it is a normal semiconductor with Rashba
splitting. Meanwhile, first-principle calculationsfailed to confirm the
existence of topological surface states in BiTeCl so far. Therefore, the
topological nature of BiTeCl requires further investigation. Here we report low
temperature scanning tunneling microscopy study on the surface states of BiTeCl
single crystals. On the tellurium-terminated surfaces with low defect density,
strong evidences for topological surface states are found in the quasi-particle
interference patterns generated by the scattering of these states, both in the
anisotropy of the scattering vectors and the fast decay of the interference
near step edges. Meanwhile, on samples with much higher defect densities, we
observed surface states that behave differently. Our results help to resolve
the current controversy on the topological nature of BiTeCl.Comment: 13pages,4figure
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Regulation of prokineticin 2 expression by light and the circadian clock
BACKGROUND: The suprachiasmatic nucleus (SCN) contains the master circadian clock that regulates daily rhythms of many physiological and behavioural processes in mammals. Previously we have shown that prokineticin 2 (PK2) is a clock-controlled gene that may function as a critical SCN output molecule responsible for circadian locomotor rhythms. As light is the principal zeitgeber that entrains the circadian oscillator, and PK2 expression is responsive to nocturnal light pulses, we further investigated the effects of light on the molecular rhythm of PK2 in the SCN. In particular, we examined how PK2 responds to shifts of light/dark cycles and changes in photoperiod. We also investigated which photoreceptors are responsible for the light-induced PK2 expression in the SCN. To determine whether light requires an intact functional circadian pacemaker to regulate PK2, we examined PK2 expression in cryptochrome1,2-deficient (Cry1-/-Cry2-/-) mice that lack functional circadian clock under normal light/dark cycles and constant darkness. RESULTS: Upon abrupt shifts of the light/dark cycle, PK2 expression exhibits transients in response to phase advances but rapidly entrains to phase delays. Photoperiod studies indicate that PK2 responds differentially to changes in light period. Although the phase of PK2 expression expands as the light period increases, decreasing light period does not further condense the phase of PK2 expression. Genetic knockout studies revealed that functional melanopsin and rod-cone photoreceptive systems are required for the light-inducibility of PK2. In Cry1-/-Cry2-/- mice that lack a functional circadian clock, a low amplitude PK2 rhythm is detected under light/dark conditions, but not in constant darkness. This suggests that light can directly regulate PK2 expression in the SCN. CONCLUSION: These data demonstrate that the molecular rhythm of PK2 in the SCN is regulated by both the circadian clock and light. PK2 is predominantly controlled by the endogenous circadian clock, while light plays a modulatory role. The Cry1-/-Cry2-/- mice studies reveal a light-driven PK2 rhythm, indicating that light can induce PK2 expression independent of the circadian oscillator. The light inducibility of PK2 suggests that in addition to its role in clock-driven rhythms of locomotor behaviour, PK2 may also participate in the photic entrainment of circadian locomotor rhythms
Path Planning for Underactuated Dubins Micro-robots Using Switching Control
In this paper, we develop an optimal path planning strategy for under-actuated Dubins micro-robots. Such robots are non-holonomic robots constrained to move along circular paths of fixed curvature clockwise or counter-clockwise. Our objective is to investigate the coverage and optimal path problems, as well as multi-robot cooperation, for a switching control scheme. Our methods are based on elementary geometry and optimal control techniques. The results in this paper show that the trajectories of micro-robots can cover the entire two-dimensional plane, and that the proposed switching control scheme allows multiple robots to cooperate. In addition, we deduce the minimum-time path under the switching control scheme by converting the robot model into the traditional Dubins vehicle model
Computing the lower and upper bounds of Laplace eigenvalue problem: by combining conforming and nonconforming finite element methods
This article is devoted to computing the lower and upper bounds of the
Laplace eigenvalue problem. By using the special nonconforming finite elements,
i.e., enriched Crouzeix-Raviart element and extension , we get
the lower bound of the eigenvalue. Additionally, we also use conforming finite
elements to do the postprocessing to get the upper bound of the eigenvalue. The
postprocessing method need only to solve the corresponding source problems and
a small eigenvalue problem if higher order postprocessing method is
implemented. Thus, we can obtain the lower and upper bounds of the eigenvalues
simultaneously by solving eigenvalue problem only once. Some numerical results
are also presented to validate our theoretical analysis.Comment: 19 pages, 4 figure
Neural networks impedance control of robots interacting with environments
In this paper, neural networks impedance control is proposed for robot-environment interaction. Iterative learning control is developed to make the robot dynamics follow a given target impedance model. To cope with the problem of unknown robot dynamics, neural networks are employed such that neither the robot structure nor the physical parameters are required for the control design. The stability and performance of the resulted closed-loop system are discussed through rigorous analysis and extensive remarks. The validity and feasibility of the proposed method are verified through simulation studies
A Facile Nanoparticle Immunoassay for Cancer Biomarker Discovery
<p>Abstract</p> <p>Background</p> <p>Gold nanoparticles (AuNPs) scatter light intensely at or near their surface plasmon wavelength region. Using AuNPs coupled with dynamic light scattering (DLS) detection, we developed a facile nanoparticle immunoassay for serum protein biomarker detection and analysis. A serum sample was first mixed with a citrate-protected AuNP solution. Proteins from the serum were adsorbed to the AuNPs to form a protein corona on the nanoparticle surface. An antibody solution was then added to the assay solution to analyze the target proteins of interest that are present in the protein corona. The protein corona formation and the subsequent binding of antibody to the target proteins in the protein corona were detected by DLS.</p> <p>Results</p> <p>Using this simple assay, we discovered multiple molecular aberrations associated with prostate cancer from both mice and human blood serum samples. From the mice serum study, we observed difference in the size of the protein corona and mouse IgG level between different mice groups (i.e., mice with aggressive or less aggressive prostate cancer, and normal healthy controls). Furthermore, it was found from both the mice model and the human serum sample study that the level of vascular endothelial growth factor (VEGF, a protein that is associated with tumor angiogenesis) adsorbed to the AuNPs is decreased in cancer samples compared to non-cancerous or less malignant cancer samples.</p> <p>Conclusion</p> <p>The molecular aberrations observed from this study may become new biomarkers for prostate cancer detection. The nanoparticle immunoassay reported here can be used as a convenient and general tool to screen and analyze serum proteins and to discover new biomarkers associated with cancer and other human diseases.</p
Study of color connections in annihilation
We replace in the event generator JETSET the color singlet chain connection
with the color separate state one as the interface between the hard and soft
sectors of hadronic processes. The modified generator is applied to produce the
hadronic events in annihilation. It describes the experimental data
at the same level as the original JETSET with default parameters. This should
be understood as a demonstration that color singlet chain is not the unique
color connection. We also search for the difference in special sets of
three-jet events arising from different color connections, which could subject
to further experimental test.Comment: 23 pages, 8 figures, 4 tables, Revtex
Integrated transcriptional profiling and genomic analyses reveal RPN2 and HMGB1 as promising biomarkers in colorectal cancer
Colorectal cancer (CRC) is a heterogeneous disease that is associated with a gradual accumulation of genetic and epigenetic alterations. Among all CRC stages, stage II tumors are highly heterogeneous with a high relapse rate in about 20-25 % of stage II CRC patients following surgery. Thus, a comprehensive analysis of gene signatures to identify aggressive and metastatic phenotypes in stage II CRC is desired for a more accurate disease classification and outcome prediction. By utilizing a Cancer Array, containing 440 oncogenes and tumor suppressors to profile mRNA expression, we identified a larger number of differentially expressed genes in poorly differentiated stage II colorectal adenocarcinoma tissues, compared to their matched normal tissues. Ontology and Ingenuity Pathway Analysis (IPA) indicated that these genes are involved in functional mechanisms associated with several transcription factors. Genomic alterations of these genes were also investigated through The Cancer Genome Atlas (TCGA) database, utilizing 195 published CRC specimens. The percentage of genomic alterations in these genes was ranked based on their mRNA expression, copy number variations and mutations. This data was further combined with published microarray studies from a large set of CRC tumors classified based on prognostic features. This led to the identification of eight candidate genes including RPN2, HMGB1, AARS, IGFBP3, STAT1, HYOU1, NQO1 and PEA15 that were associated with the progressive phenotype. In particular, RPN2 and HMGB1 displayed a higher genomic alteration frequency in CRC, compared to eight other major solid cancers. Immunohistochemistry was performed on additional 78 stage I-IV CRC samples, where RPN2 protein immunostaining exhibited a significant association with stage III/IV tumors, distant metastasis, and poor differentiation, indicating that RPN2 expression is associated with poor prognosis. Further, our study revealed significant transcriptional regulatory mechanisms, networks and gene signatures, underlying CRC malignant progression and phenotype warranting future clinical investigations.published_or_final_versio
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