77 research outputs found
Production and application of monoclonal antibodies suitable for the specific detection of listeria monocytogenes
The principal objective of this research concerned the production, characterisation and application of antibodies for the specific detection of Listeria monocytogenes.
Monoclonal antibodies were generated against various L. monocytogenes-derived antigens. Initially, a panel o f antibodies was produced against a 60 kDa extracellular protein isolated from exponentially growing L. monocytogenes culture supernatants.Subsequently, the L. monocytogenes-speclfic surface pathogenicity protein, Intemalin B (InlB), was biochemically isolated and used to generate InlB-specific monoclonal antibodies. The specific reactivity of these antibodies was demonstrated using purified recombinant InlB (rlnlB) and p60 (rp60) proteins, respectively. However, the anti-p60 antibody was cross-reactive with certain non-pathogenic members of the Listeria genus and the anti-InlB monoclonal antibody was not capable of efficiently binding InlB on the L.monocytogenes cell surface.
Thus, a third panel of monoclonal antibodies was generated using intact, formalininactivated L. monocytogenes cells as the immunogen. From this panel, a promising antibody was selected and shown to demonstrate improved specificity for the L.monocytogenes species. This antibody was further examined in order to demonstrate its potential application in traditional immunoassay and SPR-based biosensor formats.
The L. monocytogenes inlA gene was cloned into a compatible expression vector and recombinant InlA protein (rlnlA) was heterologously expressed in Escherischia coli. This was then used to confirm that the antibody was indeed specific for the L. monocytogenes pathogenicity marker, InlA. The results indicated that the anti-InlA monoclonal antibody produced was capable o f specifically binding to intact L. monocytogenes cells and therefore, it was concluded that it could potentially be employed to facilitate more rapid, reliable and specific detection o f L. monocytogenes cells
Development of a New, Precise Near-infrared Doppler Wavelength Reference: A Fiber Fabry-Perot Interferometer
We present the ongoing development of a commercially available Micron Optics
fiber-Fabry Perot Interferometer as a precise, stable, easy to use, and
economic spectrograph reference with the goal of achieving <1 m/s long term
stability. Fiber Fabry-Perot interferometers (FFP) create interference patterns
by combining light traversing different delay paths. The interference creates a
rich spectrum of narrow emission lines, ideal for use as a precise Doppler
reference. This fully photonic reference could easily be installed in existing
NIR spectrographs, turning high resolution fiber-fed spectrographs into precise
Doppler velocimeters. First light results on the Sloan Digital Sky Survey III
(SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE)
spectrograph and several tests of major support instruments are also presented.
These instruments include a SuperK Photonics fiber supercontinuum laser source
and precise temperature controller. A high resolution spectrum obtained using
the NIST 2-m Fourier transform spectrometer (FTS) is also presented. We find
our current temperature control precision of the FFP to be 0.15 mK,
corresponding to a theoretical velocity stability of 35 cm/s due to temperature
variations of the interferometer cavity.Comment: 16 pages, 11 figures. To appear in the proceedings of the SPIE 2012
Astronomical Instrumentation and Telescopes conferenc
The Habitable-Zone Planet Finder: A Stabilized Fiber-Fed NIR Spectrograph for the Hobby-Eberly Telescope
We present the scientific motivation and conceptual design for the recently
funded Habitable-zone Planet Finder (HPF), a stabilized fiber-fed near-infrared
(NIR) spectrograph for the 10 meter class Hobby-Eberly Telescope (HET) that
will be capable of discovering low mass planets around M dwarfs. The HPF will
cover the NIR Y & J bands to enable precise radial velocities to be obtained on
mid M dwarfs, and enable the detection of low mass planets around these stars.
The conceptual design is comprised of a cryostat cooled to 200K, a dual
fiber-feed with a science and calibration fiber, a gold coated mosaic echelle
grating, and a Teledyne Hawaii-2RG (H2RG) NIR detector with a 1.7m cutoff.
A uranium-neon hollow-cathode lamp is the baseline wavelength calibration
source, and we are actively testing laser frequency combs to enable even higher
radial velocity precision. We will present the overall instrument system design
and integration with the HET, and discuss major system challenges, key choices,
and ongoing research and development projects to mitigate risk. We also discuss
the ongoing process of target selection for the HPF survey.Comment: 14 pages, 9 figures. To appear in the proceedings of the SPIE 2012
Astronomical Instrumentation and Telescopes conferenc
Electrochemiluminescence platform for the detection of C-reactive proteins : application of recombinant antibody technology to cardiac biomarker detection
This work exploits the high-affinity of recombinant antibodies and low background electrochemiluminescence (ECL) for cardiac-biomarker detection. The developed assay is capable of fg mL-1 detection limits as well as the detection of C-Reactive Protein (CRP) over a clinically relevant range. The assay demonstrated robust reproducibility, selectivity and stability while also highlighting a novel platform for detection of cardiac biomarkers at low concentrations
TOI-150: A transiting hot Jupiter in the TESS southern CVZ
We report the detection of a hot Jupiter ($M_{p}=1.75_{-0.17}^{+0.14}\
M_{J}R_{p}=1.38\pm0.04\ R_{J}\log
g=4.152^{+0.030}_{-0.043}\beta=-79.59^{\circ}$). We confirm the
planetary nature of the candidate TOI-150.01 using radial velocity observations
from the APOGEE-2 South spectrograph and the Carnegie Planet Finder
Spectrograph, ground-based photometric observations from the robotic
Three-hundred MilliMeter Telescope at Las Campanas Observatory, and Gaia
distance estimates. Large-scale spectroscopic surveys, such as APOGEE/APOGEE-2,
now have sufficient radial velocity precision to directly confirm the signature
of giant exoplanets, making such data sets valuable tools in the TESS era.
Continual monitoring of TOI-150 by TESS can reveal additional planets and
subsequent observations can provide insights into planetary system
architectures involving a hot Jupiter around a star about halfway through its
main-sequence life.Comment: 13 pages, 3 figures, 2 tables, accepted to ApJ
Chandra X-ray observations of Young Clusters II. Orion Flanking Fields Data
We present results of Chandra observations of two flanking fields (FF) in
Orion, outside the Orion Nebula Cluster (ONC). The observations were taken with
the ACIS-I camera with an exposure time of about 48 ks each field. We present a
catalog of 417 sources, which includes X-ray luminosity, optical and infrared
photometry and X-ray variability information. We have found 91 variable
sources, 33 of which have a flare-like light curve, and 11 of which have a
pattern of a steady increase or decrease over a 10 hour period. The optical and
infrared photometry for the stars identified as X-ray sources are consistent
with most of these objects being pre-main sequence stars with ages younger than
10 Myr. We present evidence for an age difference among the X-ray selected
samples of NGC 2264, Orion FF, and ONC, with NGC 2264 being the oldest, and ONC
being the youngest.Comment: AJ in press, 32 pages, 13 figures in total, 5 figures available at
http://spider.ipac.caltech.edu/staff/solange/ramirez07_figs.p
Discovery of Two Rare Rigidly Rotating Magnetosphere Stars in the APOGEE Survey
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)---one of the Sloan Digital Sky Survey III programs---is using near-infrared (NIR) spectra of ~100,000 red giant branch star candidates to study the structure of the Milky Way. In the course of the survey, APOGEE also acquires spectra of hot field stars to serve as telluric calibrators for the primary science targets. We report the serendipitous discovery of two rare, fast-rotating B-stars of the sigma Ori E type among those blue field stars observed during the first year of APOGEE operations. Both of the discovered stars display the spectroscopic signatures of rigidly rotating magnetospheres (RRM) common to this class of highly magnetized (B ~ 10 kGauss) stars, increasing the number of known RRM stars by ~10%. One (HD 345439) is a main-sequence B-star with unusually strong He absorption (similar to sigma Ori E), while the other (HD 23478) fits a "He-normal" B3IV classification. We combine the APOGEE discovery spectra with other optical and NIR spectra of these two stars, and of sigma Ori E itself, to show how NIR spectroscopy can be a uniquely powerful tool for discovering more of these rare objects, which may show little/no RRM signatures in their optical spectra. We discuss the potential for further discovery of sigma Ori E type stars, as well as the implications of our discoveries for the population of these objects and insights into their origin and evolution
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in
Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
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