1,701 research outputs found
Finite Element Analysis of the Mouse Proximal Ulna in Response to Elbow Loading
Bone is a mechano-sensitive tissue that alters its structure and properties in response to mechanical loading. We have previously shown that application of lateral dynamic loads to a synovial joint, such as the knee and elbow, suppresses degradation of cartilage and prevents bone loss in arthritis and postmenopausal mouse models, respectively. While loading effects on pathophysiology have been reported, mechanical effects on the loaded joint are not fully understood. Because the direction of joint loading is non-axial, not commonly observed in daily activities, strain distributions in the laterally loaded joint are of great interest. Using elbow loading, we herein characterized mechanical responses in the loaded ulna focusing on the distribution of compressive strain. In response to 1-N peak-to-peak loads, which elevate bone mineral density and bone volume in the proximal ulna in vivo, we conducted finite-element analysis and evaluated strain magnitude in three loading conditions. The results revealed that strain of ~ 1000 μstrain (equivalent to 0.1% compression) or above was observed in the limited region near the loading site, indicating that the minimum effective strain for bone formation is smaller with elbow loading than axial loading. Calcein staining indicated that elbow loading increased bone formation in the regions predicted to undergo higher strain
Performance measurement and analysis of large filestores
PhD ThesisPerformance measurements of two large time-sharing computer systems
are presented, with emphasis on their disk filestores. Similarities
of process behaviour are found in the measured systems and another system
reported in the literature. Individual processes make i/o requests in
sequences, or bursts. Burst lengths have a mean of two with a large
variance; within a burst, file i/o requests are spatially sequential in
intent and are temporally related.
Characterizations of these behaviour patterns form the basis of a
methodology for filestore evaluation and design. Descriptions of spatial
and temporal load are abstracted from software traces without loss
of any performance factor; these descriptions are inputs to a statistical
model of the processes in the environment of the filestore. The filestore
is represented by a simulation queuing model. The method specifies the
inputs to the composite model and describes the calibration of outputs
to match observable outputs. A model is built by this method, and validated
for different loads.
The model is used for three evaluation experiments. Disk request scheduling
is not statistically significant; filestore layout and disk capacity are
highly significant; disks with fast-access areas are shown to improve
performance by taking advantage of spatial accessing patterns. The limits
of performance of a novel filestore equipped with a cache store are
explored to determine guidelines for this new design. Modest improvements
resulting from this design are shown to produce a considerable improvement
in overall system performance.The Science Research Council:
The University of Newcastle upon Tyne
The 43-kD polypeptide of heart gap junctions: immunolocalization, topology, and functional domains
Analysis by SDS-PAGE of gap junction fractions isolated from heart suggests that the junctions are comprised of a protein with an Mr 43,000. Antibodies against the electroeluted protein and a peptide representing the 20 amino terminal residues bind specifically on immunoblots to the 43-kD protein and to the major products arising from proteolysis during isolation. By immunocytochemistry, the protein is found in ventricle and atrium in patterns consistent with the known distribution of gap junctions. Both antibodies bind exclusively to gap junctions in fractions from heart examined by EM after gold labeling. Since only domains of the protein exposed at the cytoplasmic surface should be accessible to antibody, we conclude that the 43-kD protein is assembled in gap junctions with the amino terminus of the molecule exposed on the cytoplasmic side of the bilayer, that is, on the same side as the carboxy terminus as determined previously. By combining proteolysis experiments with data from immunoblotting, we can identify a third cytoplasmic region, a loop of some 4 kD between membrane protected domains. This loop carries an antibody binding site. The protein, if transmembrane, is therefore likely to cross the membrane four times. We have used the same antisera to ascertain if the 43-kD protein is involved in cell-cell communication. The antiserum against the amino terminus blocked dye coupling in 90% of cell pairs tested; the antiserum recognizing epitopes in the cytoplasmic loop and cytoplasmic tail blocked coupling in 75% of cell pairs tested. Preimmune serum and control antibodies (one against MIP and another binding to a cardiac G protein) had no or little effect on dye transfer. Our experimental evidence thus indicates that, in spite of the differences in amino acid sequence, the gap junction proteins in heart and liver share a general organizational plan and that there may be several domains (including the amino terminus) of the molecule that are involved in the control of junctional permeability
Sixth Goddard Conference on Mass Storage Systems and Technologies Held in Cooperation with the Fifteenth IEEE Symposium on Mass Storage Systems
This document contains copies of those technical papers received in time for publication prior to the Sixth Goddard Conference on Mass Storage Systems and Technologies which is being held in cooperation with the Fifteenth IEEE Symposium on Mass Storage Systems at the University of Maryland-University College Inn and Conference Center March 23-26, 1998. As one of an ongoing series, this Conference continues to provide a forum for discussion of issues relevant to the management of large volumes of data. The Conference encourages all interested organizations to discuss long term mass storage requirements and experiences in fielding solutions. Emphasis is on current and future practical solutions addressing issues in data management, storage systems and media, data acquisition, long term retention of data, and data distribution. This year's discussion topics include architecture, tape optimization, new technology, performance, standards, site reports, vendor solutions. Tutorials will be available on shared file systems, file system backups, data mining, and the dynamics of obsolescence
Real-time stream processing in radio astronomy
A major challenge in modern radio astronomy is dealing with the massive data
volumes generated by wide-bandwidth receivers. Such massive data rates are
often too great for a single device to cope, and so processing must be split
across multiple devices working in parallel. These devices must work in unison
to process incoming data in real time, reduce the data volume to a manageable
size, and output a science-ready data product. The aim of this chapter is to
give a broad overview of how digital systems for radio telescopes are commonly
implemented, with a focus on real-time stream processing over multiple compute
devices.Comment: Chapter to appear in "Big Data in Radio Astronomy: Scientific Data
Processing for Advanced Radio Telescopes
Single 5-nm quantum dot detection via microtoroid optical resonator photothermal microscopy
Label-free detection techniques for single particles and molecules play an
important role in basic science, disease diagnostics, and nanomaterial
investigations. While traditional fluorescence-based methods offer powerful
tools for single molecule detection and imaging, they are limited by a narrow
range of molecular probes and issues such as photoblinking and photobleaching.
Photothermal microscopy has emerged as a label-free imaging technique capable
of detecting individual nanoabsorbers with high sensitivity. Whispering gallery
mode microresonators can confine light in a small volume for enhanced
light-matter interaction and thus are a promising ultra-sensitive photothermal
microscopy platform. Previously microtoroid optical resonators were combined
with photothermal microscopy to detect 250 nm long gold nanorods. Here, we
combine whispering gallery mode microtoroid optical resonators with
photothermal microscopy to spatially detect 5 nm diameter quantum dots (QDs)
with a signal-to-noise ratio (SNR) exceeding . To achieve this, we
integrated our microtoroid based photothermal microscopy setup with a low
amplitude modulated pump laser and utilized the
proportional-integral-derivative (PID) controller output as the photothermal
signal source to reduce noise and enhance signal stability. The measured heat
dissipation of these 5 nm QDs is below the detectable level from single dye
molecules, showcasing the high sensitivity and discrimination capabilities of
this platform. We anticipate that our work will have application in a wide
variety of fields, including the biological sciences, nanotechnology, materials
science, chemistry, and medicine
InSight2: An Interactive Web Based Platform for Modeling and Analysis of Large Scale Argus Network Flow Data
Monitoring systems are paramount to the proactive detection and mitigation of problems in computer networks related to performance and security. Degraded performance and compromised end-nodes can cost computer networks downtime, data loss and reputation. InSight2 is a platform that models, analyzes and visualizes large scale Argus network flow data using up-to-date geographical data, organizational information, and emerging threats. It is engineered to meet the needs of network administrators with flexibility and modularity in mind. Scalability is ensured by devising multi-core processing by implementing robust software architecture. Extendibility is achieved by enabling the end user to enrich flow records using additional user provided databases. Deployment is streamlined by providing an automated installation script. State-of-the-art visualizations are devised and presented in a secure, user friendly web interface giving greater insight about the network to the end user
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