310 research outputs found
Lymphoedema - a chronic disease, not a side effect
Lymphoedema, soft tissue swelling resulting from obstruction of the lymphatic drainage system, is a chronic illness with immense physical and psychological impact on a patient’s life. Management, while conservative, can be life changing when approached by a co-ordinated multidisciplinary team. Although some patients with lymphoedema will require minimal support, it is vital that patients and healthcare professionals are vigilant for rare but serious complications
Two-layer viscous instability in a rotating couette device
A novel experiment to study the interfacial shear instability between two liquids is described. Density-matched immiscible liquids are confined between concentric cylinders such that the interface is parallel to the cylinder walls. Interfacial waves that develop because of viscosity differences between the shearing fluids are studied as a function of rotation rate and depth ratio using optical techniques. Conditions neutral stability and the most unstable wavenumber agree reasonably well with predictions from linear stability analysis of the Navier-Stokes equations. Illumination using laser sheets allows precise measurement of the interface shape. Future experiments will verify the correctness of weakly nonlinear theories that describe energy transfer and saturation of wave growth by nonlinear effects. Measurements of solitary wave shapes, that occur far above neutral stability, will be compared to similar measurements for systems that have gravity as an important force to determine how gravity effects large disturbances. These results will be used to interpret slug and annular flow data that have been obtained in other mu g studies
Fundamental Processes of Atomization in Fluid-Fluid Flows
This paper discusses our proposed experimental and theoretical study of atomization in gas-liquid and liquid-liquid flows. While atomization is a very important process in these flows, the fundamental mechanism is not understood and there is no predictive theory. Previous photographic studies in (turbulent) gas-liquid flows have shown that liquid is atomized when it is removed by the gas flow from the crest of large solitary or roll waves. Our preliminary studies in liquid-liquid laminar flows exhibit the same mechanism. The two-liquid system is easier to study than gas-liquid systems because the time scales are much slower, the length scales much larger, and there is no turbulence. The proposed work is intended to obtain information about the mechanism of formation, rate of occurrence and the evolving shape of solitary waves; and quantitative aspects of the detailed events of the liquid removal process that can be used to verify a general predictive theory
Slide FFT on a homogeneous mesh in wafer-scale computing
Searches for signals at low signal-to-noise ratios frequently involve the
Fast Fourier Transform (FFT). For high-throughput searches, we here consider
FFT on the homogeneous mesh of Processing Elements (PEs) of a wafer-scale
engine (WSE). To minimize memory overhead in the inherently non-local FFT
algorithm, we introduce a new synchronous slide operation ({\em Slide})
exploiting the fast interconnect between adjacent PEs. Feasibility of
compute-limited performance is demonstrated in linear scaling of Slide
execution times with varying array size in preliminary benchmarks on the CS-2
WSE. The proposed implementation appears opportune to accelerate and open the
full discovery potential of FFT-based signal processing in multi-messenger
astronomy.Comment: 7 pages, 6 figure
IMMACCS: A Multi-Agent Decision-Support System
This report describes work performed by the Collaborative Agent Design Research Center for the US Marine Corps Warfighting Laboratory (MCWL), on the IMMACCS experimental decision-support system. IMMACCS (Integrated Marine Multi-Agent Command and Control System) incorporates three fundamental concepts that distinguish it from existing (i.e., legacy) command and control applications. First, it is a collaborative system in which computer-based agents assist human operators by monitoring, analyzing, and reasoning about events in near real-time. Second, IMMACCS includes an ontological model of the battlespace that represents the behavioral characteristics and relationships among real world entities such as friendly and enemy assets, infrastructure objects (e.g., buildings, roads, and rivers), and abstract notions. This object model provides the essential common language that binds all IMMACCS components into an integrated and adaptive decision-support system. Third, IMMACCS provides no ready made solutions that may not be applicable to the problems that will occur in the real world. Instead, the agents represent a powerful set of tools that together with the human operators can adjust themselves to the problem situations that cannot be predicted in advance. In this respect, IMMACCS is an adaptive command and control system that supports planning, execution and training functions concurrently.
The report describes the nature and functional requirements of military command and control, the architectural features of IMMACCS that are designed to support these operational requirements, the capabilities of the tools (i.e., agents) that IMMACCS offers its users, and the manner in which these tools can be applied. Finally, the performance of IMMACCS during the Urban Warrior Advanced Warfighting Experiment held in California in March, 1999, is discussed from an operational viewpoint
RbFe2+Fe3+F6: Synthesis, Structure, and Characterization of a New Charge-Ordered Magnetically Frustrated Pyrochlore-Related Mixed-Metal Fluoride
A new charge-ordered magnetically frustrated mixed-metal fluoride with a
pyrochlore-related structure has been synthesized and characterized. The
material, RbFe2F6 (RbFe2+Fe3+F6) was synthesized through mild hydrothermal
conditions. The material exhibits a three-dimensional pyrochlore-related
structure consisting of corner-shared Fe2+F6 and Fe3+F6 octahedra. In addition
to single crystal diffraction data, neutron powder diffraction and magnetometry
measurements were carried out. Magnetic data clearly reveal strong
antiferromagnetic interactions (a Curie-Weiss temperature of -270 K) but
sufficient frustration to prevent ordering until 16 K. No structural phase
transformation is detected from the variable temperature neutron diffraction
data. Infrared, UV -vis, thermogravimetric, and differential thermal analysis
measurements were also performed. First-principles density functional theory
(DFT) electronic structure calculations were also done. Crystal data: RbFe2F6,
orthorhombic, space group Pnma (No. 62), a = 7.0177(6) {\AA}, b = 7.4499(6)
{\AA}, c = 10.1765(8) {\AA}, V = 532.04(8) {\AA}3, Z = 4
A dyad of lymphoblastic lysosomal cysteine proteases degrades the antileukemic drug L-asparaginase
l-Asparaginase is a key therapeutic agent for treatment of childhood acute lymphoblastic leukemia (ALL). There is wide individual variation in pharmacokinetics, and little is known about its metabolism. The mechanisms of therapeutic failure with l-asparaginase remain speculative. Here, we now report that 2 lysosomal cysteine proteases present in lymphoblasts are able to degrade l-asparaginase. Cathepsin B (CTSB), which is produced constitutively by normal and leukemic cells, degraded asparaginase produced by Escherichia coli (ASNase) and Erwinia chrysanthemi. Asparaginyl endopeptidase (AEP), which is overexpressed predominantly in high-risk subsets of ALL, specifically degraded ASNase. AEP thereby destroys ASNase activity and may also potentiate antigen processing, leading to allergic reactions. Using AEP-mediated cleavage sequences, we modeled the effects of the protease on ASNase and created a number of recombinant ASNase products. The N24 residue on the flexible active loop was identified as the primary AEP cleavage site. Sole modification at this site rendered ASNase resistant to AEP cleavage and suggested a key role for the flexible active loop in determining ASNase activity. We therefore propose what we believe to be a novel mechanism of drug resistance to ASNase. Our results may help to identify alternative therapeutic strategies with the potential of further improving outcome in childhood ALL
Silence on Shangri-La: attenuation of Huygens acoustic signals suggests surface volatiles
Objective: Characterize and understand acoustic instrument performance on the surface of Titan.
Methods: The Huygens probe measured the speed of sound in Titan's atmosphere with a 1 MHz pulse time-of-flight transducer pair near the bottom of the vehicle. We examine the fraction of pulses correctly received as af unction of time.
Results: This system returned good data from about 11 km altitude, where the atmosphere became thick enough to effectively transmit the sound, down to the surface just before landing: these data have been analyzed previously. After an initial transient at landing, the instrument operated nominally for about 10 min, recording pulses much as during descent. The fraction of pulses detected then declined and the transmitted sound ceased to be detected altogether, despite no indication of instrument or probe configuration changes.
Conclusions: The most likely explanation appears to be absorption of the signal by polyatomic gases with relaxation losses at the instrument frequency, such as ethane, acetylene and carbon dioxide. These vapors, detected independently by the GCMS instrument, were evolved from the surface material by the warmth leaking from the probe, and confirm the nature of the surface materials as ‘damp’ with a cocktail of volatile compounds. Some suggestions for future missions are considered.
Practice implications: None
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