68 research outputs found
Automated System for Early Breast Cancer Detection in Mammograms
The increasing demand on mammographic screening for early breast cancer detection, and the subtlety of early breast cancer signs on mammograms, suggest an automated image processing system that can serve as a diagnostic aid in radiology clinics. We present a fully automated algorithm for detecting clusters of microcalcifications that are the most common signs of early, potentially curable breast cancer. By using the contour map of the mammogram, the algorithm circumvents some of the difficulties encountered with standard image processing methods. The clinical implementation of an automated instrument based on this algorithm is also discussed
Analysis of driven nanorod transport through a biopolymer matrix
Applying magnetic fields to guide and retain drug-loaded magnetic particles in vivo has been proposed as a way of treating illnesses. Largely, these efforts have been targeted at tumors. One significant barrier to long range transport within tumors is the extracellular matrix (ECM). We perform single particle measurements of 18 nm diameter nanorods undergoing magnetophoresis through ECM, and analyze the motion of these nanorods in two dimensions. We observe intra-particle magnetophoresis in this viscoelastic environment and measure the fraction of time these nanorods spend effectively hindered, versus effectively translating
Hydrodynamic approach to the evolution of cosmological structures
A hydrodynamic formulation of the evolution of large-scale structure in the
Universe is presented. It relies on the spatially coarse-grained description of
the dynamical evolution of a many-body gravitating system. Because of the
assumed irrelevance of short-range (``collisional'') interactions, the way to
tackle the hydrodynamic equations is essentially different from the usual case.
The main assumption is that the influence of the small scales over the
large-scale evolution is weak: this idea is implemented in the form of a
large-scale expansion for the coarse-grained equations. This expansion builds a
framework in which to derive in a controlled manner the popular ``dust'' model
(as the lowest-order term) and the ``adhesion'' model (as the first-order
correction). It provides a clear physical interpretation of the assumptions
involved in these models and also the possibility to improve over them.Comment: 14 pages, 3 figures. Version to appear in Phys. Rev.
QCD axion and quintessential axion
The axion solution of the strong CP problem is reviewed together with the
other strong CP solutions. We also point out the quintessential
axion(quintaxion) whose potential can be extremely flat due to the tiny ratio
of the hidden sector quark mass and the intermediate hidden sector scale. The
quintaxion candidates are supposed to be the string theory axions, the model
independent or the model dependent axions.Comment: 15 pages. Talk presented at Castle Ringberg, June 9-14, 200
Strong-weak CP hierarchy from non-renormalization theorems
We point out that the hierarchy between the measured values of the CKM phase
and the strong CP phase has a natural origin in supersymmetry with spontaneous
CP violation and low energy supersymmetry breaking. The underlying reason is
simple and elegant: in supersymmetry the strong CP phase is protected by an
exact non-renormalization theorem while the CKM phase is not. We present
explicit examples of models which exploit this fact and discuss corrections to
the non-renormalization theorem in the presence of supersymmetry breaking. This
framework for solving the strong CP problem has generic predictions for the
superpartner spectrum, for CP and flavor violation, and predicts a preferred
range of values for electric dipole moments.Comment: 36 pages, 3 figure
Image-guided Placement of Magnetic Neuroparticles as a Potential High-Resolution Brain-Machine Interface
We are developing methods of noninvasively delivering magnetic neuroparticlesâą via intranasal administration followed by image-guided magnetic propulsion to selected locations in the brain. Once placed, the particles can activate neurons via vibrational motion or magnetoelectric stimulation. Similar particles might be used to read out neuronal electrical pulses via spintronic or liquid-crystal magnetic interactions, for fast bidirectional brain-machine interface. We have shown that particles containing liquid crystals can be read out with magnetic resonance imaging (MRI) using embedded magnetic nanoparticles and that the signal is visible even for voltages comparable to physiological characteristics. Such particles can be moved within the brain (e.g., across midline) without causing changes to neurological firing
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Image-guided Placement of Magnetic Neuroparticles as a Potential High-Resolution Brain-Machine Interface
We are developing methods of noninvasively delivering magnetic neuroparticlesâą via intranasal administration followed by image-guided magnetic propulsion to selected locations in the brain. Once placed, the particles can activate neurons via vibrational motion or magnetoelectric stimulation. Similar particles might be used to read out neuronal electrical pulses via spintronic or liquid-crystal magnetic interactions, for fast bidirectional brain-machine interface. We have shown that particles containing liquid crystals can be read out with magnetic resonance imaging (MRI) using embedded magnetic nanoparticles and that the signal is visible even for voltages comparable to physiological characteristics. Such particles can be moved within the brain (e.g., across midline) without causing changes to neurological firing
Nanocomposites of ferroelectric liquid crystals and FeCo nanoparticles: towards a magnetic response via the application of a small electric field
We study a nanocomposite consisting of a ferroelectric liquid crystal and a magnetic nanoparticle in order to explore the possibility of using it as a magnetic resonant imaging contrast agent which will measure a field of 20 V/m. To achieve this we use the ferroic properties exhibited by the nanocomposite. We used the ferroelectric liquid crystal 2-(4-((2-fluorooctyl)oxy)phenyl)-5-(octyloxy)pyrimidine mixed with FeCo nanoparticles nominally 2â3 nm in diameter in concentrations of 0.56, 4.3 and 10.8 wt%. The 10.8 wt% sample was chosen for our study because the nanoparticles acted as a lubricant for the ferroelectric liquid crystal. This concentration yields nanoparticle clusters in about 5 â 10 ÎŒm diameter spherulites. An electric field as low as 5V/cm is enough to turn and realign the spherulites where the particles are contained. We estimate the value of the magnetic in a spehrulite and associate it to the number of spherulites aligned as a function of electric field. We find thus that we can achieve low electric fields
Magnetically targeted delivery through cartilage
In this study, we have invented a method of delivering drugs deep into articular cartilage with shaped dynamic magnetic fields acting on small metallic magnetic nanoparticles with polyethylene glycol coating and average diameter of 30 nm. It was shown that transport of magnetic nanoparticles through the entire thickness of bovine articular cartilage can be controlled by a combined alternating magnetic field at 100 Hz frequency and static magnetic field of 0.8 tesla (T) generated by 1" dia. x 2" thick permanent magnet. Magnetic nanoparticles transport through bovine articular cartilage samples was investigated at various settings of magnetic field and time durations. Combined application of an alternating magnetic field and the static field gradient resulted in a nearly 50 times increase in magnetic nanoparticles transport in bovine articular cartilage tissue as compared with static field conditions. This method can be applied to locally deliver therapeutic-loaded magnetic nanoparticles deep into articular cartilage to prevent cartilage degeneration and promote cartilage repair in osteoarthritis
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