2,934 research outputs found
Ant tracheal measurements by synchrotron
No full textData for ant abdominal tracheal radii from Levels 1 (closest to spiracle) to level 3. Code for the analysis also provided as used in the R package. The data all used for this work:<div><br></div><div><p><a>Tracheal
branching in ants is area-decreasing, violating a central assumption of network
transport models</a></p>
<p> </p>
<p>Ian
J. Aitkenhead, Grant A. Duffy, Citsabehsan Devendran,
Michael R. Kearney, Adrian Neild and Steven L. Chown</p><br></div>
Ant tracheal measurements by synchrotron tomography
No full textData for ant abdominal tracheal radii from Levels 1 (closest to spiracle) to level 3. Code for the analysis also provided as used in the R package. The data all used for this work:<div><br></div><div><p><a>Tracheal
branching in ants is area-decreasing, violating a central assumption of network
transport models</a></p>
<p> </p>
<p>Ian
J. Aitkenhead, Grant A. Duffy, Citsabehsan Devendran,
Michael R. Kearney, Adrian Neild and Steven L. Chown</p><br></div>
Providence College Faculty Author Series 2012-2013: Dr. Adrian Weimer
No full textDr. Adrian Weimer (History, Providence College) discusses her new book Martyrs\u27 Mirror: Persecution and Holiness in Early New England and the cultural importance of martyrdom within Colonial America
Providence College Faculty Author Series 2012-2013: Dr. Adrian Weimer
No full textDr. Adrian Weimer (History, Providence College) discusses her new book Martyrs\u27 Mirror: Persecution and Holiness in Early New England and the cultural importance of martyrdom within Colonial America
Ant tracheal measurements by synchrotron
No full textData for ant abdominal tracheal radii from Levels 1 (closest to spiracle) to level 3. Code for the analysis also provided as used in the R package. The data all used for this work:Tracheal
branching in ants is area-decreasing, violating a central assumption of network
transport models
Ian
J. Aitkenhead, Grant A. Duffy, Citsabehsan Devendran,
Michael R. Kearney, Adrian Neild and Steven L. Chown</div
Adrian Matejka, 34th Annual ODU Literary Festival
No full textAdrian Matejka is the author of The Devil’s Garden and Mixology, which was a winner of the 2008 National Poetry Series. He is the recipient of two Illinois Arts Council Literary Awards and fellowships from Cave Canem and the Lannan Foundation. His work has been featured in American Poetry Review, The Best American Poetry 2010, and Ploughshares, among other journals and anthologies. He teaches at Southern Illinois University Edwardsville
Ultrasonic air-coupled capacitive arrays
No full textA model is developed which is capable of predicting the pressure field of a rectangular source, as measured by a finite-sized receiver. This novel method treats the problem in a new way, which allows an integration to be performed over the area of the receiver. Previously it has only been possible to model two circular transducers coaxially aligned. The model is used to identify a receiver, which can be used to measure the highly focussed pressure field from a phased array, with only a negligible effect due to the receiver size. Productions from the model are compared to experimental data, and show a good correlation.
A parabolic mirror used to focus the field from a circular device in air has been studied, and a model developed to predict the pressure field produced by this device. This is done by an approximation of the mirror surface to a grid of finely spaced points. The model correlates well with measured results. In addition, an image of a defect in a solid sample was produced.
Arrays are then used to image solid samples in air. This is done using three techniques. The first is a combined phased source and receiver, which is shown to locate a wire accurately and to measure a step in the surface of a sample. A 2-D array is shown to image a defect in a composite plate, and the potential for a fast through-transmission air-coupled system is indicated. In addition, two post-processing techniques are used on data recorded using an array receiver, to locate an object in air. Of these two techniques, ellipse crossing is shown to have better results for large signal to noise ratios, and SAFT for lower ratios.
The combination of theoretical modelling and experimental observations has indicated that the transducers and arrays constructed for use in air are well-understood, and that their characteristics can be predicted
Performing the archive: following in the footsteps
No full textUsing documentation of Mike Pearson's performance 'Bubbling Tom', Deirdre Heddon attempts to step into his shoes and re-perform it
Acoustophoresis in open fluidic films
No full textAcoustic particle manipulation (acoustophoresis) is a rapidly developing technology in the field of microfluidics, which uses small fluid samples for the purposes of biological or chemical based testing. Microfluidics is often aimed at producing Lab-on-a-Chip based systems, particularly useful for testing in remote locations where standard laboratory techniques are not available. Acoustophoresis holds advantages over many other particle manipulation methods as it only alters the fluid pressure to displace the non-homogeneous elements within the fluid. Other methods typically require application of a potential difference to the fluid, which may damage sensitive biological cells; or direct contact with the particles, which may also cause damage or cross-contamination with repeated trials. Common uses for acoustophoresis are the filtering of particles from fluid by displacing them to a location and then splitting the fluid flow (an acoustic filter), or creating arrays of particle clumps for drug testing purposes (bioassays). The actuating mechanism for these devices is typically a piezoelectric transducer (PZT), which vibrates upon application of an alternating current, attached to a carrier which is in turn coupled with the particulate fluid. This work seeks to adapt established acoustophoresis devices for novel uses. The key to the setup presented is the vertical offset between the PZT and carrier glass, which allows the carrier to be partially submerged while under actuation. The device then utilises two novel methods of acoustophoresis, the first has the fluid bounded by the edge of the glass carrier during actuation. The second method is for a partially submerged carrier that applies standing waves to an open and stationary fluid volume many times the size of the carrier itself. The advantage of the device itself is that the two piece system allows for ease of use, repetition and easily adjustable spatial parameters. The first method presented has the advantage of requiring only a small fluid volume and no external mechanisms. For a known fluid volume the actuating frequency is varied and the horizontal wavelength (determined by the distance between the lines the particles relocate to), is calculated and compared to theoretical expectations. The frequency against horizontal wavelength analysis is conducted for the open fluid method as well, in addition to recording the effect of variation in the fluid thickness layer on the acoustic wave. The open fluid setup has the advantage of the particle arrays being highly accessible and is examined compared to other acoustic methods using enclosed chambers. Both methods presented have experimental techniques adapted to exploit the advantages of the novel setup, as well as 2 dimensional COMSOL finite element models. The work produced succeeds in utilising the device presented for two alternate modes of particle manipulation, both of which present advantages over current methods of acoustophoresis
Manipulation in microfluidic systems using surface acoustic waves (SAW)
No full textLab-on-a-chip microfluidic systems hold substantial promise for a wide range of diagnostic and therapeutic applications. By shrinking down conventional laboratory processes and replicating their functions on-chip, the size, cost, required time, and amount of reagent and sample needed can be drastically reduced. However, because these devices operate at length scales orders of magnitude smaller than conventional fluid processes different physical phenomena become dominant, meaning new forces and techniques must be developed to perform them. Acoustic forces have the potential to be useful at small length scales, though, their use has for the most part been limited by the relatively small force magnitudes and low frequencies at which they have been generated, thereby limiting the promise of rapid acoustic manipulation on microfluidic scales. However, a developing technology relying on the application of surface acoustic waves (SAW) has shown the potential to overcome these limitations, especially due to the high frequencies (10-2000 MHz) and correspondingly small length scales (2-300 µm), on the order of the bacteria and eukaryotic cells, that are characteristic of this method. In this thesis, SAW is used in a range of applications that emphasize these advantages, specifically with respect to the large and localized forces that can be generated on interfaces, both between two immiscible phases and on particles within a single fluid phase. In the studies presented here, SAW is used to (1) actuate a fluid-air interface for the production of water-in-air droplets with tunable diameters in the range of ~0.5-50 µm for the purpose of targeted nebulization therapy, (2) actuate a water-oil interface for the tunable production of picoliter-sized water-in-oil droplets with simultaneous particle pre-concentration and encapsulation for application in digital microfluidic systems, (3) perform controlled concentration and release of particles using a novel microfabricated channel structure and (4) deterministically sort particles over a large size range, demonstrated between 0.3-7 µm with potential application in cell sorting systems where high sorting efficiency or sorting based on only small size differences is required. Finally the case is made that acoustic fields, especially those produced by SAW, are optimal for many, if not most, applications where manipulation of microfluidic species is required
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