580 research outputs found
Shearing Interferometer for Quantifying the Coherence of Hard X-Ray Beams
We report a quantitative measurement of the full transverse coherence function of the 14.4 keV x-ray radiation produced by an undulator at the Swiss Light Source. An x-ray grating interferometer consisting of a beam splitter phase grating and an analyzer amplitude grating has been used to measure the degree of coherence as a function of the beam separation out to 30 m. Importantly, the technique provides a model-free and spatially resolved measurement of the complex coherence function and is not restricted to high resolution detectors and small fields of view. The spatial characterization of the wave front has important applications in discovering localized defects in beam line optics
N-glycans of human amniotic fluid transferrin stimulate progesterone production in human first trimester trophoblast cells in vitro
Aims: During pregnancy, the placenta produces a variety of steroid hormones and proteins. Several of these substances have been shown to exert immunomodulatory effects. Progesterone is thought to mediate some of these effects by regulating uterine responsiveness. The aim of this study was to clarify the effect of amniotic fluid transferrin and its N-glycans on the release of progesterone by first trimester trophoblast cells in vitro. Methods: Cytotrophoblast cells were prepared from human first trimester placentae by trypsin-DNAse dispersion of villous tissue followed by a percoll gradient centrifugation and depletion of CD45 positive cells by magnetic cell sorting. Trophoblasts were incubated with varying concentrations (50-300 mug/ml) of transferrin from human amniotic fluid and serum as well as with N-glycans obtained from amniotic fluid transferrin. Culture supernatants were assayed for progesterone by enzyme-immunometric methods. Results: The release of progesterone increased in amniotic fluid transferrin- and N-glycan-treated trophoblast cell cultures compared to untreated trophoblast cells. There was no stimulating effect of serum transferrin on the progesterone production of trophoblast cells. Conclusions: The results suggest that amnion-transferrin and especially its N-glycans modulate the endocrine function of trophoblasts in culture by up regulating progesterone secretion
The Consistency of Ratings on the Cab-T Executive Functioning Scale as Compared to the Brief
Executive functioning is an umbrella term used to describe abilities that include self-monitoring, goal-setting, planning, organization, attention, and working memory. Broadband behavior rating scales are commonly used by school psychologists and the instruments often now include an executive functioning scale. It is unknown, however, how these scales, based on a few items, compare to more extensive rating scales that solely measure executive functioning. The current study examined the overall consistency between the executive functioning scale on one broadband instrument to another instrument that assesses multiple areas of executive functioning by having teachers complete both instruments at the same point in time. The comparisons revealed statistically significant correlations, but significantly different mean scores between the executive functioning CAB-T score and the overall BRIEF score. Furthermore, classification consistency (i.e., scores from the two scales are both in the average range or clinically significant range) only occurred approximately two-thirds of the time. Thus, concerns were raised about the use of the scale from the broadband instrument as a general measure of executive functioning
Observation of a local gravity potential isosurface by airborne lidar of Lake Balaton, Hungary
Airborne lidar is a remote sensing method commonly
used for mapping surface topography in high resolution.
A water surface in hydrostatic equilibrium theoretically
represents a gravity potential isosurface. Here we compare
lidar-based ellipsoidal water surface height measurements all
around the shore of a major lake with a local high-resolution
quasi-geoid model. The ellipsoidal heights of the 87 km2 we
sampled all around the shore of the 597 km2 lake surface vary
by 0.8m and strong spatial correlation with the quasi-geoid
undulation was calculated (R2 = 0.91). After subtraction of
the local geoid undulation from the measured ellipsoidal water
surface heights, their variation was considerably reduced.
Based on a network of water gauge measurements, dynamic
water surface heights were also successfully corrected for.
This demonstrates that the water surface heights of the lake
were truly determined by the local gravity potential.We conclude
that both the level of hydrostatic equilibrium of the lake
and the accuracy of airborne lidar were sufficient for identifying
the spatial variations of gravity potential
ASSESSMENT OF BOTTOM-OF-ATMOSPHERE REFLECTANCE IN LIDAR DATA AS REFERENCE FOR HYPERSPECTRAL IMAGERY
While airborne lidar has confirmed its leading role in delivering high-resolution 3D topographic information during the last decade, its
radiometric potential has not yet been fully exploited. However, with the increasing availability of commercial lidar systems which (a)
make use of full-waveform information and (b) operate at several wavelengths simultaneously, this potential is increasing as well. Radiometric
calibration of the full-waveform information mentioned before allows for the derivation of physical target surface parameters
such as the backscatter coefficient and a diffuse reflectance value at bottom of atmosphere (BOA), i.e. the target surface.
With lidar being an active remote sensing technique, these parameters can be derived from lidar data itself, accompanied by the
measurement or estimation of reference data for diffuse reflectance. In contrast to this, such a radiometric calibration for passive
hyperspectral imagery (HSI) requires the knowledge and/or estimation of much more unknowns. However, in case of corresponding
wavelength(s) radiometrically calibrated lidar datasets can deliver an areawide reference for BOA reflectance.
This paper presents criteria to check where the assumption of diffuse BOA reflectance behaviour is fulfilled and how these criteria are
assessed in lidar data; the assessment is illustrated by an extended lidar dataset. Moreover, for this lidar dataset and an HSI dataset
recorded over the same area, the corresponding reflectance values are compared for different surface types
RIGOROUS STRIP ADJUSTMENT OF AIRBORNE LASERSCANNING DATA BASED ON THE ICP ALGORITHM
Airborne Laser Scanning (ALS) is an efficient method for the acquisition of dense and accurate point clouds over extended areas. To
ensure a gapless coverage of the area, point clouds are collected strip wise with a considerable overlap. The redundant information
contained in these overlap areas can be used, together with ground-truth data, to re-calibrate the ALS system and to compensate for
systematic measurement errors. This process, usually denoted as strip adjustment, leads to an improved georeferencing of the ALS
strips, or in other words, to a higher data quality of the acquired point clouds. We present a fully automatic strip adjustment method that
(a) uses the original scanner and trajectory measurements, (b) performs an on-the-job calibration of the entire ALS multisensor system,
and (c) corrects the trajectory errors individually for each strip. Like in the Iterative Closest Point (ICP) algorithm, correspondences
are established iteratively and directly between points of overlapping ALS strips (avoiding a time-consuming segmentation and/or
interpolation of the point clouds). The suitability of the method for large amounts of data is demonstrated on the basis of an ALS block
consisting of 103 strips
Resonance Raman Spectroscopy For In-Situ Monitoring Of Radiation Damage
Radiation induced damage of metal centres in proteins is a severe problem in X-ray structure determination. Photoreduction can lead to erroneous structural implications, and in the worst cases cause structure solution to fail. Resonance Raman (RR) spectroscopy is well suited in-situ monitoring of X-ray induced photoreduction. However the laser excitation needed for RR can itself cause photoreduction of the metal centres. In the present study myoglobin and rubredoxin crystals were used as model systems to assess the feasibility of using RR for this application. It is shown that at least 10-15 RR spectra per crystal can be recorded at low laser power before severe photoreduction occurs.Furthermore it is possible to collect good quality RR spectra from cryocooled protein crystals with exposure times of only a few seconds. Following extended laser illumination photoreduction is observed through the formation and decay of spectral bands as a function of dose. The experimental setup planned for integration into the SLS protein crystallography beamlines is also described. This setup should also prove to be very useful for other experimental techniques at synchrotrons where X-ray photoreduction is a problem e.g. X-ray absorption spectroscopy.Fil: Meents, A.. Swiss Light Source; SuizaFil: Owen, R. L.. Swiss Light Source; SuizaFil: Murgida, Daniel Horacio. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de QuĂmica, FĂsica de los Materiales, Medioambiente y EnergĂa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de QuĂmica, FĂsica de los Materiales, Medioambiente y EnergĂa; ArgentinaFil: Hildebrandt, P.. Swiss Light Source; SuizaFil: Schneider, R.. Swiss Light Source; SuizaFil: Pradervand, C.. Swiss Light Source; SuizaFil: Bohler, P.. Swiss Light Source; SuizaFil: Schulze Briese, C.. Swiss Light Source; Suiz
Automated Classification of Airborne Laser Scanning Point Clouds
Making sense of the physical world has always been at the core of mapping. Up
until recently, this has always dependent on using the human eye. Using
airborne lasers, it has become possible to quickly "see" more of the world in
many more dimensions. The resulting enormous point clouds serve as data sources
for applications far beyond the original mapping purposes ranging from flooding
protection and forestry to threat mitigation. In order to process these large
quantities of data, novel methods are required. In this contribution, we
develop models to automatically classify ground cover and soil types. Using the
logic of machine learning, we critically review the advantages of supervised
and unsupervised methods. Focusing on decision trees, we improve accuracy by
including beam vector components and using a genetic algorithm. We find that
our approach delivers consistently high quality classifications, surpassing
classical methods
Longitudinal molecular microbial analysis of influenza-like illness in New York City, may 2009 through may 2010
<p>Abstract</p> <p>Background</p> <p>We performed a longitudinal study of viral etiology in samples collected in New York City during May 2009 to May 2010 from outpatients with fever or respiratory disease symptoms in the context of a pilot respiratory virus surveillance system.</p> <p>Methods</p> <p>Samples were assessed for the presence of 13 viruses, including influenza A virus, by MassTag PCR.</p> <p>Results</p> <p>At least one virus was detected in 52% of 940 samples analyzed, with 3% showing co-infections. The most frequently detected agents were rhinoviruses and influenza A, all representing the 2009 pandemic H1N1 strain. The incidence of influenza H1N1-positive samples was highest in late spring 2009, followed by a decline in summer and early fall, when rhinovirus infections became predominant before H1N1 reemerged in winter. Our study also identified a focal outbreak of enterovirus 68 in the early fall of 2009.</p> <p>Conclusion</p> <p>MassTag multiplex PCR affords opportunities to track the epidemiology of infectious diseases and may guide clinicians and public health practitioners in influenza-like illness and outbreak management. Nonetheless, a substantial proportion of influenza-like illness remains unexplained underscoring the need for additional platforms.</p
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