387 research outputs found
A novel role for proliferin-2 in the ex vivo expansion of hematopoietic stem cells
AbstractA family of proliferin genes was discovered on a microarray analysis of hematopoiesis supportive stromal cell lines. Proliferin-2 (PLF2) increased the frequency of long-term culture-initiating cells (LTC-IC) from 1 in 340 to 1 in 256 of the primary hematopoietic stem cell (HSC)-enriched bone marrow cells grown on MS5.1 feeder layer. A repeat using AFT024 feeder layer also showed a similar increase in LTC-IC (from 1 in 386 cells to 1 in 260 cells). The clonogenic output of the LTC-ICs was also increased significantly. The growth of various hematopoietic and stromal cell lines treated with PLF2 was found to increase by 4–27%, as measured by cell count and DNA synthesis assay. These findings open up the possibility of using PLF2 as a new member of the growth factor cocktails for the ex vivo expansion of HSC
Geometric calibration of focused light field camera for 3-D flame temperature measurement
Focused light field camera can be used to measure three-dimensional (3-D) temperature field of a flame because of its ability to record intensity and direction information of each ray from flame simultaneously. This work aims to develop a suitable geometric calibration method of focused light field camera for 3-D flame temperature measurement. A modified method based on Zhang's camera calibration is developed to calibrate the camera and the measurement system. A single focused light-field camera is used to capture images of bespoke calibration board for calibration in this study. Geometric parameters including intrinsic (i.e., camera parameters) and extrinsic (i.e., camera connecting with the calibration board) of the focused light field camera are calibrated to trace the ray projecting onto each pixel on CCD (charge-coupled device) sensor. Instead of using line features, corner point features are directly utilized for the calibration. The characteristics of focused light field camera including one 3-D point corresponding to several image points and matching main lens and microlens f-numbers, are used for calibration. Results with a focused light field camera are presented and discussed. Preliminary 3-D temperature distribution of a flame is also investigated and presented
Optical ridge waveguides in Er3+/Yb3+ co-doped phosphate glass produced by ion irradiation combined with femtosecond laser ablation for guided-wave green and red upconversion emissions
This work reports on the fabrication of ridge waveguides in Er3+/Yb3+ co-doped phosphate glass by the combination of femtosecond laser ablation and following swift carbon ion irradiation. The guiding properties of waveguides have been investigated at 633 and 1064 nm through end face coupling arrangement. The refractive index profile on the cross section of the waveguide has been constructed. The propagation losses can be reduced considerably after annealing treatment. Under the optical pump laser at 980 nm, the upconversion emission of both green and red fluorescence has been realized through the ridge waveguide structures.This work was supported by the National Natural Science Foundation of China (No. 11305094). S.Z. acknowledges the funding by the Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF-VH-NG-713). J.R. Vázquez de Aldana thanks the support from Junta de Castilla y León (Project SA086A12-2)
Early Triassic microbialites from the Changxing Region of Zhejiang Province, South China
© 2019, The Author(s). Microbialites, often considered as a signal of extreme marine environment, are common in the Lower Triassic strata of South China where they flourished in the aftermath of the end-Permian mass extinction. Early Triassic microbialite facies are known to vary palaeogeographically, perhaps due to differing climates, ocean chemistry, and water depths. This paper provides the first record of a brief, but spectacular development of microbialites in the aftermath of the end-Permian mass extinction at Panjiazhuang section, Changxing Region of Zhejiang Province (eastern South China). Here, the Upper Permian Changxing Formation comprises typical shallow platform facies rich in calcareous algae and foraminifera, the development of which was terminated by the major end-Permian regression. A 3.4-m-thick microbialite began to form at the onset of the transgression in the earliest Triassic. The microbialite at Panjiazhuang section is composed of thrombolite that contains abundant calcified cyanobacteria, small gastropods, microconchid tubes and ostracods, representing a low-diversity shallow marine community in the aftermath of the end-Permian crisis. The microbialites are succeeded by thin-bedded micrites bearing thin-shelled bivalves, which record a rapid sea-level rise in the Early Triassic. Abundant populations of small pyrite framboids are observed in the upper part of the microbialites and the overlying thin-bedded micrites, suggesting that dysoxic water conditions developed at that time. The appearance of microbialites near the Permian–Triassic boundary (PTB) at Panjiazhuang section was the result of peculiar marine conditions following the end-Permian regression, whilst their disappearance was due to the increasing water depth and the development of dysoxia
Ultrafast 3-D Super Resolution Ultrasound using Row-Column Array specific Coherence-based Beamforming and Rolling Acoustic Sub-aperture Processing: In Vitro, In Vivo and Clinical Study
The row-column addressed array is an emerging probe for ultrafast 3-D
ultrasound imaging. It achieves this with far fewer independent electronic
channels and a wider field of view than traditional 2-D matrix arrays, of the
same channel count, making it a good candidate for clinical translation.
However, the image quality of row-column arrays is generally poor, particularly
when investigating tissue. Ultrasound localisation microscopy allows for the
production of super-resolution images even when the initial image resolution is
not high. Unfortunately, the row-column probe can suffer from imaging artefacts
that can degrade the quality of super-resolution images as `secondary' lobes
from bright microbubbles can be mistaken as microbubble events, particularly
when operated using plane wave imaging. These false events move through the
image in a physiologically realistic way so can be challenging to remove via
tracking, leading to the production of 'false vessels'. Here, a new type of
rolling window image reconstruction procedure was developed, which integrated a
row-column array-specific coherence-based beamforming technique with acoustic
sub-aperture processing for the purposes of reducing `secondary' lobe
artefacts, noise and increasing the effective frame rate. Using an {\it{in
vitro}} cross tube, it was found that the procedure reduced the percentage of
`false' locations from 26\% to 15\% compared to traditional
orthogonal plane wave compounding. Additionally, it was found that the noise
could be reduced by 7 dB and that the effective frame rate could be
increased to over 4000 fps. Subsequently, {\it{in vivo}} ultrasound
localisation microscopy was used to produce images non-invasively of a rabbit
kidney and a human thyroid
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