180 research outputs found
Data Fusion of Objects Using Techniques Such as Laser Scanning, Structured Light and Photogrammetry for Cultural Heritage Applications
In this paper we present a semi-automatic 2D-3D local registration pipeline
capable of coloring 3D models obtained from 3D scanners by using uncalibrated
images. The proposed pipeline exploits the Structure from Motion (SfM)
technique in order to reconstruct a sparse representation of the 3D object and
obtain the camera parameters from image feature matches. We then coarsely
register the reconstructed 3D model to the scanned one through the Scale
Iterative Closest Point (SICP) algorithm. SICP provides the global scale,
rotation and translation parameters, using minimal manual user intervention. In
the final processing stage, a local registration refinement algorithm optimizes
the color projection of the aligned photos on the 3D object removing the
blurring/ghosting artefacts introduced due to small inaccuracies during the
registration. The proposed pipeline is capable of handling real world cases
with a range of characteristics from objects with low level geometric features
to complex ones
Impedance model for a high-temperature ceramic humidity sensor
We present an equivalent circuit model for a titanium dioxide-based humidity
sensor which enables discrimination of three separate contributions to the
sensor impedance. The first contribution, the electronic conductance,
consists of a temperature-dependent ohmic resistance. The second contribution
arises from the ionic pathway, which forms depending on the relative humidity
on the sensor surface. It is modeled by a constant-phase element (CPE) in
parallel with an ohmic resistance. The third contribution is the capacitance
of the double layer which forms at the blocking electrodes and is modeled by
a second CPE in series to the first CPE. This model was fitted to
experimental data between 1 mHz and 1 MHz recorded at different sensor
temperatures (between room temperature and 320 âC) and different
humidity levels. The electronic conductance becomes negligible at low sensor
temperatures, whereas the double-layer capacitance becomes negligible at high
sensor temperatures in the investigated frequency range. Both the
contribution from the ionic pathway and from the double-layer capacitance
strongly depend on the relative humidity and are, therefore, suitable sensor
signals. The findings define the parameters for the development of a
dedicated Fourier-based impedance spectroscope with much faster acquisition
times, paving a way for impedance-based high-temperature humidity sensor
systems.</p
Observation of Space-Charge-Limited Transport in InAs Nanowires
Recent theory and experiment have suggested that space-charge-limited
transport should be prevalent in high aspect-ratio semiconducting nanowires. We
report on InAs nanowires exhibiting this mode of transport and utilize the
underlying theory to determine the mobility and effective carrier concentration
of individual nanowires, both of which are found to be diameter-dependent.
Intentionally induced failure by Joule heating supports the notion of
space-charge-limited transport and proposes reduced thermal conductivity due to
the nanowires polymorphism
Master Equation Study of Hydrogen Relaxation Using Complete Sets of State-to-state Transition Rates
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97096/1/AIAA2012-362.pd
Development of a GPU-based Monte Carlo dose calculation code for coupled electron-photon transport
Monte Carlo simulation is the most accurate method for absorbed dose
calculations in radiotherapy. Its efficiency still requires improvement for
routine clinical applications, especially for online adaptive radiotherapy. In
this paper, we report our recent development on a GPU-based Monte Carlo dose
calculation code for coupled electron-photon transport. We have implemented the
Dose Planning Method (DPM) Monte Carlo dose calculation package (Sempau et al,
Phys. Med. Biol., 45(2000)2263-2291) on GPU architecture under CUDA platform.
The implementation has been tested with respect to the original sequential DPM
code on CPU in phantoms with water-lung-water or water-bone-water slab
geometry. A 20 MeV mono-energetic electron point source or a 6 MV photon point
source is used in our validation. The results demonstrate adequate accuracy of
our GPU implementation for both electron and photon beams in radiotherapy
energy range. Speed up factors of about 5.0 ~ 6.6 times have been observed,
using an NVIDIA Tesla C1060 GPU card against a 2.27GHz Intel Xeon CPU
processor.Comment: 13 pages, 3 figures, and 1 table. Paper revised. Figures update
Human Galectins Induce Conversion of Dermal Fibroblasts into Myofibroblasts and Production of Extracellular Matrix: Potential Application in Tissue Engineering and Wound Repair
Members of the galectin family of endogenous lectins are potent adhesion/growth-regulatory effectors. Their multi-functionality opens possibilities for their use in bioapplications. We studied whether human galectins induce the conversion of human dermal fibroblasts into myofibroblasts (MFBs) and the production of a bioactive extracellular matrix scaffold is suitable for cell culture. Testing a panel of galectins of all three subgroups, including natural and engineered variants, we detected activity for the proto-type galectin-1 and galectin-7, the chimera-type galectin-3 and the tandem-repeat-type galectin-4. The activity of galectin-1 required the integrity of the carbohydrate recognition domain. It was independent of the presence of TGF-beta 1, but it yielded an additive effect. The resulting MFBs, relevant, for example, for tumor progression, generated a matrix scaffold rich in fibronectin and galectin-1 that supported keratinocyte culture without feeder cells. Of note, keratinocytes cultured on this substratum presented a stem-like cell phenotype with small size and keratin-19 expression. In vivo in rats, galectin-1 had a positive effect on skin wound closure 21 days after surgery. In conclusion, we describe the differential potential of certain human galectins to induce the conversion of dermal fibroblasts into MFBs and the generation of a bioactive cell culture substratum. Copyright (C) 2011 S. Karger AG, Base
Metal-Free Room-Temperature Vulcanization of Silicones via Borane Hydrosilylation
Vulcanization of silicone networks from commercially available linear poly(dimethyl-co-methylhydro)siloxane (PMHS) and α-diketones was achieved using metal-free borane hydrosilylation at room temperature. The Lewis acid catalyst, tris(pentafluorophenyl)borane (B(C_6F_5)_3), efficiently cross-linked PMHS at minimal catalyst loadings (200â1000 ppm) to produce polymer networks with mechanical properties, thermal stability, and optical clarity rivaling that achieved from traditional platinum catalysis. Variation of the starting PMHS structure is shown to influence the final characteristics of the network. Increasing molar mass of the PMHS chain results in a higher thermal decomposition temperature, while increasing mole fractions of SiâH moieties along the backbone increase the cross-linking density and the attendant Shore hardness. The degradation behavior of the networks was investigated, with the borane-vulcanized samples showing rapid dissolution upon exposure to acid and high stability to neutral and basic conditions. Functional networks bearing halide and vinyl groups could also be prepared via a preliminary reaction of PMHS with an appropriate monoketone, providing a general and versatile strategy for network derivatization with the potential for postvulcanization functionalization being subsequently demonstrated via thiolâene click chemistry
Metal-Free Room-Temperature Vulcanization of Silicones via Borane Hydrosilylation
Vulcanization of silicone networks from commercially available linear poly(dimethyl-co-methylhydro)siloxane (PMHS) and α-diketones was achieved using metal-free borane hydrosilylation at room temperature. The Lewis acid catalyst, tris(pentafluorophenyl)borane (B(C_6F_5)_3), efficiently cross-linked PMHS at minimal catalyst loadings (200â1000 ppm) to produce polymer networks with mechanical properties, thermal stability, and optical clarity rivaling that achieved from traditional platinum catalysis. Variation of the starting PMHS structure is shown to influence the final characteristics of the network. Increasing molar mass of the PMHS chain results in a higher thermal decomposition temperature, while increasing mole fractions of SiâH moieties along the backbone increase the cross-linking density and the attendant Shore hardness. The degradation behavior of the networks was investigated, with the borane-vulcanized samples showing rapid dissolution upon exposure to acid and high stability to neutral and basic conditions. Functional networks bearing halide and vinyl groups could also be prepared via a preliminary reaction of PMHS with an appropriate monoketone, providing a general and versatile strategy for network derivatization with the potential for postvulcanization functionalization being subsequently demonstrated via thiolâene click chemistry
Cigarette smoke induces genetic instability in airway epithelial cells by suppressing FANCD2 expression
Chromosomal abnormalities are commonly found in bronchogenic carcinoma cells, but the molecular causes of chromosomal instability (CIN) and their relationship to cigarette smoke has not been defined. Because the Fanconi anaemia (FA)/BRCA pathway is essential for maintenance of chromosomal stability, we tested the hypothesis that cigarette smoke suppresses that activity of this pathway. Here, we show that cigarette smoke condensate (CSC) inhibited translation of FANCD2 mRNA (but not FANCC or FANCG) in normal airway epithelial cells and that this suppression of FANCD2 expression was sufficient to induce both genetic instability and programmed cell death in the exposed cell population. Cigarette smoke condensate also suppressed FANCD2 function and induced CIN in bronchogenic carcinoma cells, but these cells were resistant to CSC-induced apoptosis relative to normal airway epithelial cells. We, therefore, suggest that CSC exerts pressure on airway epithelial cells that results in selection and emergence of genetically unstable somatic mutant clones that may have lost the capacity to effectively execute an apoptotic programme. Carcinogen-mediated suppression of FANCD2 gene expression provides a plausible molecular mechanism for CIN in bronchogenic carcinogenesis
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