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Search Results: 1 - 10 of 345144 matches for " D. G. Middleton "
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A rare case of a retroperitoneal enterogenous cyst with in-situ adenocarcinoma
Jeffrey T Lordan, Robin L Jones, Nariman D Karanjia, Stefano de Sanctis, James G Woodland, Gary Middleton, Neville Menezes
World Journal of Surgical Oncology , 2007, DOI: 10.1186/1477-7819-5-113
Abstract: We present the third described case of a retroperitoneal enterogenous cyst with adenocarcinomatous changes and only the second reported case whereby the cyst was not arising from any anatomical structure.This case demonstrates the difficulties in making a diagnosis as well as the importance of a multi-disciplinary approach, and raises further questions regarding post-operative treatment with chemotherapy.We present a patient with a retroperitoneal enterogenous cyst that contained adenocarcinoma cells presenting in adulthood. To date, only 3 cases have been reported of retroperitoneal enterogenous cysts [1-3] and only a further 2 cases of such cysts developing adenocarcinomatous changes[4,5].In 2002, a 54 year old man presented with mild heart-burn. Incidental "hepatomegaly" was found on examination accompanied by a slightly elevated bilirubin but otherwise normal liver function. A computerized tomography (CT) scan reported a well defined cyst arising from the right lower pole of the liver, measuring 14 × 12 × 10 cm (figure 1). Hydatid was excluded and the cyst was thought to be simple and benign, due to the absence of calcification. It was decided to treat this conservatively and the patient was discharged.Four years later, he re-presented with a 5-month history of intermittent dull right sided abdominal pain and a right sided palpable abdominal mass was palpated. Liver function tests revealed a bilirubin of 29 but no other abnormalities. His α-feto-protein was 3 and CA 19.9 was 22129.The repeat CT scan concurred with the previous scan, reporting a large benign cyst, with a maximum diameter of 16 cm. Figure 1 demonstrates the CT with the cyst, and the marker is the measure of the maximum diameter. Endoscopic ultrasound demonstrated a frond-like mucosal prominence within the cyst wall lining.At laparotomy, the cyst was found to be retroperitoneal lateral to the right psoas muscle, displacing the pancreas and duodenum medially, the liver superiorly and the right kidne
Stable Isotropic Cosmological Singularities in Quadratic Gravity
John D. Barrow,Jonathan Middleton
Physics , 2007, DOI: 10.1103/PhysRevD.75.123515
Abstract: We show that, in quadratic lagrangian theories of gravity, isotropic cosmological singularities are stable to the presence of small scalar, vector and tensor inhomogeneities. Unlike in general relativity, a particular exact isotropic solution is shown to be the stable attractor on approach to the initial cosmological singularity. This solution is also known to act as an attractor in Bianchi universes of types I, II and IX, and the results of this paper reinforce the hypothesis that small inhomogeneous and anisotropic perturbations of this attractor form part of the general cosmological solution to the field equations of quadratic gravity. Implications for the existence of a 'gravitational entropy' are also discussed.
The Stability of an Isotropic Cosmological Singularity in Higher-Order Gravity
Jonathan Middleton,John D. Barrow
Physics , 2008, DOI: 10.1103/PhysRevD.77.103523
Abstract: We study the stability of the isotropic vacuum Friedmann universe in gravity theories with higher-order curvature terms of the form $(R_{ab}R^{ab})^{n}$ added to the Einstein-Hilbert Lagrangian of general relativity on approach to an initial cosmological singularity. Earlier, we had shown that, when $% n=1$, a special isotropic vacuum solution exists which behaves like the radiation-dominated Friedmann universe and is stable to anisotropic and small inhomogeneous perturbations of scalar, vector and tensor type. This is completely different to the situation that holds in general relativity, where an isotropic initial cosmological singularity is unstable in vacuum and under a wide range of non-vacuum conditions. We show that when $n\neq 1$, although a special isotropic vacuum solution found by Clifton and Barrow always exists, it is no longer stable when the initial singularity is approached. We find the particular stability conditions under the influence of tensor, vector, and scalar perturbations for general $n$ for both solution branches. On approach to the initial singularity, the isotropic vacuum solution with scale factor $a(t)=t^{P_{-}/3}$ is found to be stable to tensor perturbations for $0.51$ and is unstable as $t \to 0$ for all $n$ for each type of perturbation.
Knockout of proton-neutron pairs from $^{16}$O with electromagnetic probes
D. G. Middleton,J. R. M. Annand,C. Barbieri,C. Giusti,P. Grabmayr,T. Hehl,I. J. D. MacGregor,I. Martin,J. C. McGeorge,F. Moschini,F. D. Pacati,M. Schwamb,D. Watts
Physics , 2009, DOI: 10.1140/epja/i2009-10902-7
Abstract: After recent improvements to the Pavia model of two-nucleon knockout from $^{16}$O with electromagnetic probes the calculated cross sections are compared to experimental data from such reactions. Comparison with data from a measurement of the $^{16}$O(e,e$'$pn) reaction show much better agreement between experiment and theory than was previously observed. In a comparison with recent data from a measurement of the $^{16}$O($\gamma$,pn) reaction the model over-predicts the measured cross section at low missing momentum.
Holographic characterization of imperfect colloidal spheres
Mark Hannel,Christine Middleton,David G. Grier
Physics , 2015, DOI: 10.1063/1.4932948
Abstract: We demonstrate precise measurements of the size and refractive index of individual dimpled colloidal spheres using holographic characterization techniques developed for ideal spheres.
NASA Goddard’s LiDAR, Hyperspectral and Thermal (G-LiHT) Airborne Imager
Bruce D. Cook,Lawrence A. Corp,Ross F. Nelson,Elizabeth M. Middleton,Douglas C. Morton,Joel T. McCorkel,Jeffrey G. Masek,Kenneth J. Ranson,Vuong Ly,Paul M. Montesano
Remote Sensing , 2013, DOI: 10.3390/rs5084045
Abstract: The combination of LiDAR and optical remotely sensed data provides unique information about ecosystem structure and function. Here, we describe the development, validation and application of a new airborne system that integrates commercial off the shelf LiDAR hyperspectral and thermal components in a compact, lightweight and portable system. Goddard’s LiDAR, Hyperspectral and Thermal (G-LiHT) airborne imager is a unique system that permits simultaneous measurements of vegetation structure, foliar spectra and surface temperatures at very high spatial resolution (~1 m) on a wide range of airborne platforms. The complementary nature of LiDAR, optical and thermal data provide an analytical framework for the development of new algorithms to map plant species composition, plant functional types, biodiversity, biomass and carbon stocks, and plant growth. In addition, G-LiHT data enhance our ability to validate data from existing satellite missions and support NASA Earth Science research. G-LiHT’s data processing and distribution system is designed to give scientists open access to both low- and high-level data products (http://gliht.gsfc.nasa.gov), which will stimulate the community development of synergistic data fusion algorithms. G-LiHT has been used to collect more than 6,500?km 2 of data for NASA-sponsored studies across a broad range of ecoregions in the USA and Mexico. In this paper, we document G-LiHT design considerations, physical specifications, instrument performance and calibration and acquisition parameters. In addition, we describe the data processing system and higher-level data products that are freely distributed under NASA’s Data and Information policy.
A variable ultraluminous X-ray source in a globular cluster in NGC 4649
T. P. Roberts,G. Fabbiano,B. Luo,D. -W. Kim,J. Strader,M. J. Middleton,J. P. Brodie,T. Fragos,J. S. Gallagher,V. Kalogera,A. R. King,A. Zezas
Physics , 2012, DOI: 10.1088/0004-637X/760/2/135
Abstract: We report the discovery of a new ultraluminous X-ray source (ULX) associated with a globular cluster in the elliptical galaxy NGC 4649. The X-ray source was initially detected with a luminosity below 5 x 10^38 erg/s, but in subsequent observations 7 and 11 years later it had brightened substantially to 2 - 3 x 10^39 erg/s. Over the course of six separate observations it displayed significant spectral variability, in both continuum slope and absorption column. Short-term variability in the X-ray flux was also present in at least one observation. The properties of this object appear consistent with a stellar-mass black hole accreting at super-Eddington rates (i.e. in the ultraluminous accretion state), although a highly super-Eddington neutron star cannot be excluded. The coincidence of an increase in absorption column with a possible enhancement in short-term variability in at least one observation is suggestive of a clumpy radiatively-driven wind crossing our line-of-sight to the object
A Helium Gas-Scintillator Active Target for Photoreaction Measurements
R. Al Jebali,J. R. M. Annand,J. -O. Adler,I. Akkurt,E. Buchanan,J. Brudvik,K. Fissum,S. Gardner,D. J. Hamilton,K. Hansen,L. Isaksson,K. Livingston,M. Lundin,J. C. McGeorge,I. J. D. MacGregor,R. MacRae,D. G. Middleton,A. J. H. Reiter,G. Rosner,B. Schr?der,J. Sj?gren,D. Sokhan,B. Strandberg
Physics , 2015,
Abstract: A multi-cell He gas-scintillator active target, designed for the measurement of photoreaction cross sections, is described. The target has four main chambers, giving an overall thickness of 0.103 $\mathrm{g/cm^{2}}$ at an operating pressure of 2 MPa. Scintillations are read out by photomultiplier tubes and the addition of small amounts of $\mathrm{N}_{2}$ to the He, to shift the scintillation emission from UV to visible, is discussed. First results of measurements at the MAX IV Laboratory tagged-photon facility show that the target has good timing resolution and can cope well with a high-flux photon beam. The determination of reaction cross sections from target yields relies on a Monte Carlo simulation, which considers scintillation light transport, photodisintegration processes in $^{4}\mathrm{He}$, background photon interactions in target windows and interactions of the reaction-product particles in the gas and target container. The predictions of this simulation are compared to the measured target response.
New Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities
L. S. Myers,J. R. M. Annand,J. Brudvik,G. Feldman,K. G. Fissum,H. W. Grie?hammer,K. Hansen,S. S. Henshaw,L. Isaksson,R. Jebali,M. A. Kovash,M. Lundin,J. A. McGovern,D. G. Middleton,A. M. Nathan,D. R. Phillips,B. Schr?der,S. C. Stave
Statistics , 2014, DOI: 10.1103/PhysRevLett.113.262506
Abstract: The electromagnetic polarizabilities of the nucleon are fundamental properties that describe its response to external electric and magnetic fields. They can be extracted from Compton-scattering data --- and have been, with good accuracy, in the case of the proton. In contradistinction, information for the neutron requires the use of Compton scattering from nuclear targets. Here we report a new measurement of elastic photon scattering from deuterium using quasimonoenergetic tagged photons at the MAX IV Laboratory in Lund, Sweden. These first new data in more than a decade effectively double the world dataset. Their energy range overlaps with previous experiments and extends it by 20 MeV to higher energies. An analysis using Chiral Effective Field Theory with dynamical \Delta(1232) degrees of freedom shows the data are consistent with and within the world dataset. After demonstrating that the fit is consistent with the Baldin sum rule, extracting values for the isoscalar nucleon polarizabilities and combining them with a recent result for the proton, we obtain the neutron polarizabilities as \alpha_n = [11.55 +/- 1.25(stat) +/- 0.2(BSR) +/- 0.8(th)] X 10^{-4} fm^3 and \beta_n = [3.65 -/+ 1.25(stat) +/- 0.2(BSR) -/+ 0.8(th)] X 10^{-4} fm3, with \chi^2 = 45.2 for 44 degrees of freedom.
Mesenchymal Stem Cells Exhibit Firm Adhesion, Crawling, Spreading and Transmigration across Aortic Endothelial Cells: Effects of Chemokines and Shear
Giselle Chamberlain,Helen Smith,G. Ed Rainger,Jim Middleton
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0025663
Abstract: Mesenchymal stem cells (MSCs) have anti-inflammatory and immunosuppressive properties and may be useful in the therapy of diseases such as arteriosclerosis. MSCs have some ability to traffic into inflamed tissues, however to exploit this therapeutically their migratory mechanisms need to be elucidated. This study examines the interaction of murine MSCs (mMSCs) with, and their migration across, murine aortic endothelial cells (MAECs), and the effects of chemokines and shear stress. The interaction of mMSCs with MAECs was examined under physiological flow conditions. mMSCs showed lack of interaction with MAECs under continuous flow. However, when the flow was stopped (for 10min) and then started, mMSCs adhered and crawled on the endothelial surface, extending fine microvillous processes (filopodia). They then spread extending pseudopodia in multiple directions. CXCL9 significantly enhanced the percentage of mMSCs adhering, crawling and spreading and shear forces markedly stimulated crawling and spreading. CXCL9, CXCL16, CCL20 and CCL25 significantly enhanced transendothelial migration across MAECs. The transmigrated mMSCs had down-regulated receptors CXCR3, CXCR6, CCR6 and CCR9. This study furthers the knowledge of MSC transendothelial migration and the effects of chemokines and shear stress which is of relevance to inflammatory diseases such as arteriosclerosis.
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