1,603 research outputs found
Theory of longitudinal emission computed tomography and the practical application to cardiac imaging
Longitudinal Emission Computed Tomography (LECT) is a radioisotope imaging technique which has found particular use in cardiac investigations. However, its clinical use has revealed Imaging problems which show themselves as reconstruction artefacts or false defects. The basis for the imaging problem of LECT is established theoretically using a simple analysis which shows that the reconstruction will predict that activity lies outside the object volume. The volume of the reconstruction lying outside the object volume is considered as an error volume, by using simple, unmodified back projection. This is the first time such a concept has been developed and it is used to calculate an error volume index (EVI). This index is shown to be useful for assessing and comparing LECT systems. It is used to examine the reduction of the error volume by modifications to LECT systems.
Thallium-201 perfusion imaging for ischaemic heart disease and infarct detection using a rotating slant hole (RSH) LECT system is compared to conventional planar imaging and X-ray contrast arteriography. RSHLECT is shown not to improve the diagnostic performance of planar imaging. The tomograms suffer from artefacts which appear as defects in the myocardium. Although the presence of these artefacts have been demonstrated by other workers this study shows that they have a significant affect on the diagnostic performance of the technique. A computer simulation and experimental studies using a simulated cardiac chamber are used to study the source of the problem. The origin of the artefacts is demonstrated for the first time.
The problem of the error volume in reconstructing the cardiac blood pool is considered. Three techniques to correct the reconstruction volume are examined and one is recommended which will reduce the error volume. Computer simulation and experimental studies with a simulated blood pool are used to examine this problem. It is shown that it is not possible to correct the reconstruction volume when an iterative least squares reconstruction technique is used together with the assumption of a uniform activity distribution; this implies the need for an alternative predictive function. The Inability to correct the reconstruction volume for a simple uniform activity distribution show that, for Thallium-201 perfusion Imaging where the distribution is non-uniform, there is a need for an imaging system modified to reduce the error volume. This work concerning a blood pool LECT reconstruction and correction of the reconstruction volume is original.
For the clinical trial of Thallium-201 perfusion imaging and the experimental work with a simulated cardiac chamber, a rotating slant hole LECT system was used. The physical performance of this system was measured and compared with other LECT systems. In doing this a relationship between plane density in the reconstruction and inter-planar resolution is demonstrated for the first time
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Combination Therapy for Human Immunodeficiency Virus-Associated Cryptococcal Meningitis: Whom, When, and Where?
Funny walking : the rise, fall and rise of the Anglo-American comic eccentric dancer
This article will attempt to reposition comic eccentric dance as a metamorphic form that still, surprisingly, exists, and is to be found with reasonable ubiquity, in renewed incarna-tions within twenty first century media.
Tracing the origins of comic eccentric dance through examples of earlier comedy performance, and drawing from Bergson’s comic theory of body misalliance, this article will dis-cuss this particularly ludic fusion of music and comedy. Further changes to the form affected by modernist preoccupations during the new Jazz Age at the turn of the twentieth century will be suggested. Finally, ways in which the formulation lives on in twenty-first century in-carnations in the comedy work of, for instance, Jimmy Fallon and Ricky Gervase, and in popular television shows such as Strictly Come Dancing (BBC 2004 - ) and Britain’s Got Talent (ITV 2006 - ) will be posited
Measuring the Loschmidt amplitude for finite-energy properties of the Fermi-Hubbard model on an ion-trap quantum computer
Calculating the equilibrium properties of condensed matter systems is one of
the promising applications of near-term quantum computing. Recently, hybrid
quantum-classical time-series algorithms have been proposed to efficiently
extract these properties from a measurement of the Loschmidt amplitude from initial states and a
time evolution under the Hamiltonian up to short times . In this
work, we study the operation of this algorithm on a present-day quantum
computer. Specifically, we measure the Loschmidt amplitude for the
Fermi-Hubbard model on a -site ladder geometry (32 orbitals) on the
Quantinuum H2-1 trapped-ion device. We assess the effect of noise on the
Loschmidt amplitude and implement algorithm-specific error mitigation
techniques. By using a thus-motivated error model, we numerically analyze the
influence of noise on the full operation of the quantum-classical algorithm by
measuring expectation values of local observables at finite energies. Finally,
we estimate the resources needed for scaling up the algorithm.Comment: 18 pages, 12 figure
A full degree-of-freedom photonic crystal spatial light modulator
Harnessing the full complexity of optical fields requires complete control of
all degrees-of-freedom within a region of space and time -- an open goal for
present-day spatial light modulators (SLMs), active metasurfaces, and optical
phased arrays. Here, we solve this challenge with a programmable photonic
crystal cavity array enabled by four key advances: (i) near-unity vertical
coupling to high-finesse microcavities through inverse design, (ii) scalable
fabrication by optimized, 300 mm full-wafer processing, (iii)
picometer-precision resonance alignment using automated, closed-loop
"holographic trimming", and (iv) out-of-plane cavity control via a high-speed
micro-LED array. Combining each, we demonstrate near-complete spatiotemporal
control of a 64-resonator, two-dimensional SLM with nanosecond- and
femtojoule-order switching. Simultaneously operating wavelength-scale modes
near the space- and time-bandwidth limits, this work opens a new regime of
programmability at the fundamental limits of multimode optical control.Comment: 25 pages, 20 figure
An international standardization programme towards the application of gene expression profiling in routine leukaemia diagnostics: the Microarray Innovations in LEukemia study prephase
Gene expression profiling has the potential to enhance current methods for the diagnosis of haematological malignancies. Here, we present data on 204 analyses from an international standardization programme that was conducted in 11 laboratories as a prephase to the Microarray Innovations in LEukemia (MILE) study. Each laboratory prepared two cell line samples, together with three replicate leukaemia patient lysates in two distinct stages: (i) a 5-d course of protocol training, and (ii) independent proficiency testing. Unsupervised, supervised, and r2 correlation analyses demonstrated that microarray analysis can be performed with remarkably high intra-laboratory reproducibility and with comparable quality and reliability
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
The evolution of white-tailed jackrabbit camouflage in response to past and future seasonal climates
Low-dose salinomycin induces anti-leukemic responses in AML and MLL
Development of anti-cancer drugs towards clinical application is costly and inefficient. Large screens of drugs, efficacious for non-cancer disease, are currently being used to identify candidates for repurposing based on their anti-cancer properties. Here, we show that low-dose salinomycin, a coccidiostat ionophore previously identified in a breast cancer screen, has anti-leukemic efficacy. AML and MLLr cell lines, primary cells and patient samples were sensitive to submicromolar salinomycin. Most strikingly, colony formation of normal hematopoietic cells was unaffected by salinomycin, demonstrating a lack of hemotoxicity at the effective concentrations. Furthermore, salinomycin treatment of primary cells resulted in loss of leukemia repopulation ability following transplantation, as demonstrated by extended recipient survival compared to controls. Bioinformatic analysis of a 17-gene signature identified and validated in primary MLLr cells, uncovered immunomodulatory pathways, hubs and protein interactions as potential transducers of low dose salinomycin treatment. Additionally, increased protein expression of p62/Sqstm1, encoded for by one of the 17 signature genes, demonstrates a role for salinomycin in aggresome/vesicle formation indicative of an autophagic response.Together, the data support the efficacy of salinomycin as an anti-leukemic at non-hemotoxic concentrations. Further investigation alone or in combination with other therapies is warranted for future clinical trial
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
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