6,601 research outputs found
Development of image processing tools for measurementof beam straightness
The objective was to measure the straightness of steel beams as a non-contact mean and using image processing techniques. This work deals with the development of an image processing methodology to be employed in an inspection machine for measurement of straightness of moving steel beams. The method was embodied in a software that reads the position of the beams, correlates all the positions monitored by the cameras, and reports the quality of straightness of the beam.
The inspection machine uses computer vision technology as a non contact measuring device. Video cameras are used to log information about the lateral position and height of steel beams while rolling on a conveyor from the production process.
The number of cameras and the distance between them are user defined parameters. The technique developed is prepared to guarantee the measuring system operation if one camera is switched off or fails. This implies the ability of this system on using more than 3 cameras.
The system output is the non linearity deviation of the beam, compensating factors for lateral or angular movements in the horizontal measuring plane of the beam and the beam profile. The output is displayed in a computer screen, according to the line method and the least squares method
Comments on noncommutative gravity
We study the possibility of obtaining noncommutative gravity dynamics from
string theory in the Seiberg-Witten limit. We find that the resulting
low-energy theory contains more interaction terms than those proposed in
noncommutative deformations of gravity. The role of twisted diffeomorphisms in
string theory is studied and it is found that they are not standard physical
symmetries. It is argued that this might be the reason why twisted
diffeomorphisms are not preserved by string theory in the low energy limit.
Twisted gauge transformations are also discussed.Comment: 37 pages. Typos corrected. Final version to appear in Nuclear Physics
Carotenoid triplet state formation in Rhodobacter sphaeroides R-26 reaction centers exchanged with modified bacteriochlorophyll pigments and reconstituted with spheroidene
Triplet state electron paramagnetic resonance (EPR) experiments have been carried out at X-band on Rb. sphaeroides R-26 reaction centers that have been reconstituted with the carotenoid, spheroidene, and exchanged with 132-OH-Zn-bacteriochlorophyll a and [3-vinyl]-132-OH-bacteriochlorophyll a at the monomeric, lsquoaccessoryrsquo bacteriochlorophyll sites BA,B or with pheophytin a at the bacteriopheophytin sites HA,B. The primary donor and carotenoid triplet state EPR signals in the temperature range 95–150 K are compared and contrasted with those from native Rb. sphaeroides wild type and Rb. sphaeroides R-26 reaction centers reconstituted with spheroidene. The temperature dependencies of the EPR signals are strikingly different for the various samples. The data prove that triplet energy transfer from the primary donor to the carotenoid is mediated by the monomeric, BChlB molecule. Furthermore, the data show that triplet energy transfer from the primary donor to the carotenoid is an activated process, the efficiency of which correlates with the estimated triplet state energies of the modified pigments
A Geometrical Method of Decoupling
The computation of tunes and matched beam distributions are essential steps
in the analysis of circular accelerators. If certain symmetries - like midplane
symmetrie - are present, then it is possible to treat the betatron motion in
the horizontal, the vertical plane and (under certain circumstances) the
longitudinal motion separately using the well-known Courant-Snyder theory, or
to apply transformations that have been described previously as for instance
the method of Teng and Edwards. In a preceeding paper it has been shown that
this method requires a modification for the treatment of isochronous cyclotrons
with non-negligible space charge forces. Unfortunately the modification was
numerically not as stable as desired and it was still unclear, if the extension
would work for all thinkable cases. Hence a systematic derivation of a more
general treatment seemed advisable.
In a second paper the author suggested the use of real Dirac matrices as
basic tools to coupled linear optics and gave a straightforward recipe to
decouple positive definite Hamiltonians with imaginary eigenvalues. In this
article this method is generalized and simplified in order to formulate a
straightforward method to decouple Hamiltonian matrices with eigenvalues on the
real and the imaginary axis. It is shown that this algebraic decoupling is
closely related to a geometric "decoupling" by the orthogonalization of the
vectors , and , that were introduced with the
so-called "electromechanical equivalence". We present a structure-preserving
block-diagonalization of symplectic or Hamiltonian matrices, respectively. When
used iteratively, the decoupling algorithm can also be applied to n-dimensional
systems and requires iterations to converge to a given
precision.Comment: 13 pages, 1 figur
The Receptor AXL Diversifies EGFR Signaling and Limits the Response to EGFR-Targeted Inhibitors in Triple-Negative Breast Cancer Cells
The relationship between drug resistance, changes in signaling, and emergence of an invasive phenotype is well appreciated, but the underlying mechanisms are not well understood. Using machine learning analysis applied to the Cancer Cell Line Encyclopedia database, we identified expression of AXL, the gene that encodes the epithelial-to-mesenchymal transition (EMT)–associated receptor tyrosine kinase (RTK) AXL, as exceptionally predictive of lack of response to ErbB family receptor–targeted inhibitors. Activation of EGFR (epidermal growth factor receptor) transactivated AXL, and this ligand-independent AXL activity diversified EGFR-induced signaling into additional downstream pathways beyond those triggered by EGFR alone. AXL-mediated signaling diversification was required for EGF (epidermal growth factor)–elicited motility responses in AXL-positive TNBC (triple-negative breast cancer) cells. Using cross-linking coimmunoprecipitation assays, we determined that AXL associated with EGFR, other ErbB receptor family members, MET (hepatocyte growth factor receptor), and PDGFR (platelet-derived growth factor receptor) but not IGF1R (insulin-like growth factor 1 receptor) or INSR (insulin receptor). From these AXL interaction data, we predicted AXL-mediated signaling synergy for additional RTKs and validated these predictions in cells. This alternative mechanism of receptor activation limits the use of ligand-blocking therapies and indicates against therapy withdrawal after acquired resistance. Further, subadditive interaction between EGFR- and AXL-targeted inhibitors across all AXL-positive TNBC cell lines may indicate that increased abundance of EGFR is principally a means to transactivation-mediated signaling.United States. Dept. of Defense (Congressionally Directed Medical Research Programs, Breast Cancer Research Program (W81XWH-11-1-0088))National Science Foundation (U.S.) (Graduate Research Fellowship)Repligen Corporation (Fellowship in Cancer Research)National Cancer Institute (U.S.). Integrative Cancer Biology Program (1-U54-CA112967)David H. Koch Institute for Integrative Cancer Research at MIT (Frontier Research Program Initiator Award)National Institutes of Health (U.S.) (NIH R01-CA96504
A passive GHz frequency-division multiplexer/demultiplexer based on anisotropic magnon transport in magnetic nanosheets
The emerging field of magnonics employs spin waves and their quanta, magnons,
to implement wave-based computing on the micro- and nanoscale. Multi-frequency
magnon networks allow for parallel data processing within single logic elements
whereas this is not the case with conventional transistor-based electronic
logic. However, a lack of experimentally proven solutions to efficiently
combine and separate magnons of different frequencies has impeded the intensive
use of this concept. In this Letter, we demonstrate the experimental
realization of a spin-wave demultiplexer enabling frequency-dependent
separation of GHz signals. The device is based on two-dimensional magnon
transport in the form of spin-wave beams in unpatterned magnetic nanosheets.
The intrinsic frequency-dependence of the beam direction is exploited to
realize a passive functioning obviating an external control and additional
power consumption. This approach paves the way to magnonic multiplexing
circuits enabling simultaneous information transport and processing.Comment: 16 pages, 3 figure
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