7,908 research outputs found
Inertial Focusing of Particles in Curved Micro-channels
Inertial focusing is the migration of particles in flow laterally across a channel into well-defined equilibrium positions. In microfluidic channels, inertial focusing takes advantage of hydrodynamic interactions even at high flow speeds. Particle isolation through inertial focusing is a high throughput method of processing biological samples for point-of-care diagnostics. While photos provide qualitative analyses of inertial focusing, we desired quantitative characterization of these systems. In this study, we ran flow experiments, first with fluorescent polystyrene beads and later with cells in solution, through curved micro-channels at controlled rates using a syringe pump. Our results from polystyrene bead experiments confirmed previous studies on flow through curved micro-channels, in which particles are focused along both sides of the channel at low flow rates and transition towards the center of the channel as the flow rate increases. FWHM analysis also showed that the streamline width is minimized at an intermediate flow rate, indicating inertial focusing is optimized under that condition. As this method of analysis was confirmed with polystyrene beads, we further used this analysis method to characterize the focusing of cells in solution. To maximize both throughput and purity, microfluidic devices must be designed to operate at the highest flow rate at which effective separation from bulk fluid can occur. The device presented in this report indeed isolates the desired target cells to be studied in downstream characterization.http://deepblue.lib.umich.edu/bitstream/2027.42/169578/1/Honors_Capstone_Anna_Kaehr.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/169578/2/Kaehr_Anna_Capstone_Poster.pptxhttp://deepblue.lib.umich.edu/bitstream/2027.42/169578/3/Capstone_Presentation_Video_Anna_Kaehr.mp
Phenotypic heterogeneity of peripheral monocytes in healthy dogs
Monocytes are key cells of the innate immune system. Their phenotypic and functional roles have been investigated in humans, mice and other animals, such as the rat, pig and cow. To date, detailed phenotypic analysis of monocytes has not been undertaken in dogs. Two important surface markers in human monocytes are CD14 and MHC class II (MHC II). By flow cytometry, we demonstrated that canine monocytes can be subdivided into three separate populations: CD14posMHC IIneg, CD14posMHC IIpos and CD14negMHC IIpos. Both light and transmission electron microscopy confirmed the monocytic identity of all three populations. The CD14posMHC IIneg population could be distinguished on an ultrastructural level by their smaller size, the presence of more numerous, larger granules, and more pseudopodia than both of the other populations
Vertical beaming of wavelength-scale photonic crystal resonators
We report that of the photons generated inside a photonic crystal
slab resonator can be funneled within a small divergence angle of . The far-field radiation properties of a photonic crystal slab
resonant mode are modified by tuning the cavity geometry and by placing a
reflector below the cavity. The former method directly shapes the near-field
distribution so as to achieve directional and linearly-polarized far-field
patterns. The latter modification takes advantage of the interference effect
between the original waves and the reflected waves to enhance the
energy-directionality. We find that, regardless of the slab thickness, the
optimum distance between the slab and the reflector closely equals one
wavelength of the resonance under consideration. We have also discussed an
efficient far-field simulation algorithm based on the finite-difference
time-domain method and the near- to far-field transformation.Comment: 14 pages, 15 figures, submitted to Phys. Rev.
Graduate dress code: How undergraduates are planning to use hair, clothes and make-up to smooth their transition to the workplace
This article explores the relationship between students’ identities, their ideas about professional appearance and their anticipated transition to the world of work. It is based on a series of semi-structured interviews with 13 students from a vocationally-focused university in England. It was found that participants viewed clothing and appearance as an important aspect of their transition to the workplace. They believed that, if carefully handled, their appearance could help them to fit in and satisfy the expectations of employers, although some participants anticipated that this process of fitting in might compromise their identity and values. The article addresses students’ anticipated means of handling the tension between adapting to a new environment and ‘being themselves’. It is argued that the way this process is handled is intertwined with wider facets of identity – most notably those associated with gender.The article is based on research funded by the University of Derby. © 2015 IP Publishing Ltd. ((http://www.ippublishing.com). Reproduced by permission
The VLBA Calibrator Search for the BeSSeL Survey
We present the results of a survey of radio continuum sources near the
Galactic plane using the Very Long Baseline Array (VLBA). Our observations are
designed to identify compact extragalactic sources of milliarcsecond size that
can be used for parallax measurements in the Bar and Spiral Structure Legacy
Survey. We selected point sources from the NVSS and CORNISH catalogs with flux
densities above 30 mJy and within 1.5\degr of known maser targets. Of the
1529 sources observed, 199 were detected. For sources detected on 3 or more
baselines, we determined accurate positions and evaluated their quality as
potential calibrators. Most of the 1330 sources that were not detected with the
VLBA are probably of extragalactic origin.Comment: 27 pages, 3 figures, 3 tables. Table 3 is available on the homepage
of the BeSSeL survey:
http://www.mpifr-bonn.mpg.de/staff/abrunthaler/BeSSeL/index.shtm
A-Polynomials of fillings of the Whitehead sister
Knots obtained by Dehn filling the Whitehead sister link include some of the
smallest volume twisted torus knots. Here, using results on A-polynomials of
Dehn fillings, we give formulas to compute the A-polynomials of these knots.
Our methods also apply to more general Dehn fillings of the Whitehead sister
link complement.Comment: 15 pages, 11 figure
Magnetic field induced lattice anomaly inside the superconducting state of CeCoIn: evidence of the proposed Fulde-Ferrell-Larkin-Ovchinnikov state
We report high magnetic field linear magnetostriction experiments on
CeCoIn single crystals. Two features are remarkable: (i) a sharp
discontinuity in all the crystallographic axes associated with the upper
superconducting critical field that becomes less pronounced as the
temperature increases; (ii) a distinctive second order-like feature observed
only along the c-axis in the high field (10 T ) low
temperature ( 0.35 K) region. This second order transition is
observed only when the magnetic field lies within 20 of the ab-planes and
there is no signature of it above , which raises questions regarding
its interpretation as a field induced magnetically ordered phase. Good
agreement with previous results suggests that this anomaly is related to the
transition to the Fulde-Ferrel-Larkin-Ovchinnikov superconducting state.Comment: 3 figures, 5 page
Radiation pattern of a classical dipole in a photonic crystal: photon focusing
The asymptotic analysis of the radiation pattern of a classical dipole in a
photonic crystal possessing an incomplete photonic bandgap is presented. The
far-field radiation pattern demonstrates a strong modification with respect to
the dipole radiation pattern in vacuum. Radiated power is suppressed in the
direction of the spatial stopband and strongly enhanced in the direction of the
group velocity, which is stationary with respect to a small variation of the
wave vector. An effect of radiated power enhancement is explained in terms of
\emph{photon focusing}. Numerical example is given for a square-lattice
two-dimensional photonic crystal. Predictions of asymptotic analysis are
substantiated with finite-difference time-domain calculations, revealing a
reasonable agreement.Comment: Submitted to Phys. Rev.
Revisiting the Hanbury Brown-Twiss set-up for fractional statistics
The Hanbury Brown-Twiss experiment has proved to be an effective means of
probing statistics of particles. Here, in a set-up involving edge-state
quasiparticles in a fractional quantum Hall system, we show that a variant of
the experiment composed of two sources and two sinks can be used to unearth
fractional statistics. We find a clear cut signature of the statistics in the
equal-time current-current correlation function for quasiparticle currents
emerging from the two sources and collected at the sinks.Comment: 4 pages, 3 figure
Evaluating the impact of career management skills module and internship programme within a university business school
This study evaluates the impact of an intervention on business school graduates’ employability comprising of a curriculum-based career management skills (CMS) module and an industrial placement year. The study uses data from the destinations of leavers of higher education survey to examine the employability of different groups within the cohort (no intervention, CMS module only and CMS module plus structured work experience). It finds that structured work experience has clear, positive effects on the ability of graduates to secure employment in ‘graduate level’ jobs within six months of graduation. Furthermore, participation in the CMS module also has a clear, positive effect upon the ability of participants to secure employment
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