5,923 research outputs found
Why I believe nanoparticles are crucial as a carrier for targeted drug delivery
Nanoparticles are the only materials small enough to target cells in the body, and therefore are crucial to targeted drug delivery. Issues with the synthesis, consistency, and bioactivity of these molecules are still being addressed, but base on current proof of concept studies there is a reason to believe that the ‘holy grail’ of targeted drug delivery might someday be achieved using nanoparticle‐based systems. WIREs Nanomed Nanobiotechnol 2013. doi: 10.1002/wnan.1226This article is categorized under:Therapeutic Approaches and Drug Discovery > Emerging TechnologiesDiagnostic Tools > In Vitro Nanoparticle-Based SensingTherapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic DiseasePeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142452/1/wnan1226.pd
The need to pursue and publish clinical trials in nanomedicine
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87037/1/141_ftp.pd
Guest Editorial
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63108/1/105072501750159633.pd
A Compton telescope for remote location and identification of radioactive material
The spare detectors from NASA Compton Gamma-Ray Observatory COMPTEL instrument have been reconfigured to demonstrate the capability at ground level to remotely locate and identify sources of g radiation or the movement of material that might shield γ-ray sources. The Gamma-Ray Experimental Telescope Assembly (GRETA) employs two 28 cm diameter scintillation detectors separated by 81 cm: one 8.5 cm thick liquid scintillator detector and one 7.5 cm thick NaI(Tl) detector. The assembly electronics and real-time data acquisition system measures the energy deposits and time-of- flight for each coincident detection and compiles histograms of total energy and incident angle as computed using the kinematics of Compton scattering. The GRETA field of view is a cone with full angle approximately 120°. The sensitive energy range is 0.3 to 2.6 MeV. Energy resolution is ~10% FWHM. The angular resolution, ~19° in the simplified configuration tested, will improve to better than 5° with well-defined enhancements to the data acquisition hardware and data analysis routines. When operated in the mode that was used in space, the instrument is capable of measuring and imaging up to 30 MeV with an angular resolution of 1.5°. The response of the instrument was mapped in the laboratory with 14 Ci 22Na source 3 m from the instrument. Later, we conducted demonstrations under two measurement scenarios. In one, the remotely located instrument observed an increase of background radiation counts at 1.4 MeV when a large amount of lead was removed from a building and a corresponding decrease when the lead was replaced. In the other scenario, the location and isotope-identifying energy spectrum of a 500 μCi137Cs source 3-5 m from the instrument with two intervening walls was determined in less than one minute. We report details of the instrument design and these measurements
Reducing reflections from mesh refinement interfaces in numerical relativity
Full interpretation of data from gravitational wave observations will require
accurate numerical simulations of source systems, particularly binary black
hole mergers. A leading approach to improving accuracy in numerical relativity
simulations of black hole systems is through fixed or adaptive mesh refinement
techniques. We describe a manifestation of numerical interface truncation error
which appears as slowly converging, artificial reflections from refinement
boundaries in a broad class of mesh refinement implementations, potentially
compromising the effectiveness of mesh refinement techniques for some numerical
relativity applications if left untreated. We elucidate this numerical effect
by presenting a model problem which exhibits the phenomenon, but which is
simple enough that its numerical error can be understood analytically. Our
analysis shows that the effect is caused by variations in finite differencing
error generated across low and high resolution regions, and that its slow
convergence is caused by the presence of dramatic speed differences among
propagation modes typical of 3+1 relativity. Lastly, we resolve the problem,
presenting a class of finite differencing stencil modifications, termed
mesh-adapted differencing (MAD), which eliminate this pathology in both our
model problem and in numerical relativity examples.Comment: 7 page
Position Resolution in LaBr3 and LaCl3 Scintillators Using Position-Sensitive Photomultiplier Tubes
Advanced scintillator materials such as LaBr3:Ce and LaCl3:Ce hold great promise for future hard X-ray and gamma-ray astrophysics missions due to their high density, high light output, good linearity, and fast decay times. Of particular importance for future space-based imaging instruments, such as coded-aperture telescopes, is the precise spatial location of individual gamma-ray interactions. We have investigated the position and energy resolution achievable within monolithic (5 cm × 5 cm × 1 cm) LaBr3:Ce and LaCl3:Ce crystals using position-sensitive light readout devices, including a position-sensitive photomultiplier tube and a multi-anode photomultiplier tube. We present the results of these tests and discuss the applicability of such advanced scintillators to future high-energy imaging astrophysics missions
The Final Merger of Black-Hole Binaries
Recent breakthroughs in the field of numerical relativity have led to
dramatic progress in understanding the predictions of General Relativity for
the dynamical interactions of two black holes in the regime of very strong
gravitational fields. Such black-hole binaries are important astrophysical
systems and are a key target of current and developing gravitational-wave
detectors. The waveform signature of strong gravitational radiation emitted as
the black holes fall together and merge provides a clear observable record of
the process. After decades of slow progress, these mergers and the
gravitational-wave signals they generate can now be routinely calculated using
the methods of numerical relativity. We review recent advances in understanding
the predicted physics of events and the consequent radiation, and discuss some
of the impacts this new knowledge is having in various areas of astrophysics.Comment: 57 pages; 9 figures. Updated references & fixed typos. Published
version is at
http://www.annualreviews.org/doi/abs/10.1146/annurev.nucl.010909.08324
Black-hole binaries, gravitational waves, and numerical relativity
Understanding the predictions of general relativity for the dynamical
interactions of two black holes has been a long-standing unsolved problem in
theoretical physics. Black-hole mergers are monumental astrophysical events,
releasing tremendous amounts of energy in the form of gravitational radiation,
and are key sources for both ground- and space-based gravitational-wave
detectors. The black-hole merger dynamics and the resulting gravitational
waveforms can only be calculated through numerical simulations of Einstein's
equations of general relativity. For many years, numerical relativists
attempting to model these mergers encountered a host of problems, causing their
codes to crash after just a fraction of a binary orbit could be simulated.
Recently, however, a series of dramatic advances in numerical relativity has
allowed stable, robust black-hole merger simulations. This remarkable progress
in the rapidly maturing field of numerical relativity, and the new
understanding of black-hole binary dynamics that is emerging is chronicled.
Important applications of these fundamental physics results to astrophysics, to
gravitational-wave astronomy, and in other areas are also discussed.Comment: 54 pages, 42 figures. Some typos corrected & references updated.
Essentially final published versio
- …