122 research outputs found
Scrambled and Unscrambled Turbulence
The linked fluid dynamics videos depict Rayleigh-Taylor turbulence when
driven by a complex acceleration profile involving two stages of acceleration
interspersed with a stage of stabilizing deceleration. Rayleigh-Taylor (RT)
instability occurs at the interface separating two fluids of different
densities, when the lighter fluid is accelerated in to the heavier fluid. The
turbulent mixing arising from the development of the miscible RT instability is
of key importance in the design of Inertial Confinement Fusion capsules, and to
the understanding of astrophysical events, such as Type Ia supernovae. By
driving this flow with an accel-decel-accel profile, we have investigated how
structures in RT turbulence are affected by a sudden change in the direction of
the acceleration first from destabilizing acceleration to deceleration, and
followed by a restoration of the unstable acceleration. By studying turbulence
under such highly non-equilibrium conditions, we hope to develop an
understanding of the response and recovery of self-similar turbulence to sudden
changes in the driving acceleration.Comment: 3 pages article, Two videos are include
SPARC-LoRa: A Scalable, Power-efficient, Affordable, Reliable, and Cloud Service-enabled LoRa Networking System for Agriculture Applications
With the rapid development of cloud and edge computing, Internet of Things
(IoT) applications have been deployed in various aspects of human life. In this
paper, we design and implement a holistic LoRa-based IoT system with LoRa
communication capabilities, named SPARC-LoRa, which consists of field sensor
nodes and a gateway connected to the Internet. SPARC-LoRa has the following
important features. First, the proposed wireless network of SPARC-LoRa is
even-driven and using off-the-shelf microcontroller and LoRa communication
modules with a customized PCB design to integrate all the hardware. This
enables SPARC-LoRa to achieve low power consumption, long range communication,
and low cost. With a new connection-based upper layer protocol design, the
scalability and communication reliability of SPARC-loRa can be achieved.
Second, an open source software including sensor nodes and servers is designed
based on Docker container with cloud storage, computing, and LTE
functionalities. In order to achieve reliable wireless communication under
extreme conditions, a relay module is designed and applied to SPARC-LoRa to
forward the data from sensor nodes to the gateway node. The system design and
implementation is completely open source and hosted on the DigitalOcean Droplet
Cloud. Hence, the proposed system enables further research and applications in
both academia and industry. The proposed system has been tested in real fields
under different and extreme environmental conditions in Salt Lake City, Utah
and the University of Nebraska-Lincoln. The experimental results validate the
features of SPARC-LoRa including low power, reliability, and cloud services
provided by SPARC-LoRa.Comment: 6 pages, 8 figures, submitted for publicatio
Development of a risk score for early saphenous vein graft failure: An individual patient data meta-analysis
Objectives: Early saphenous vein graft (SVG) occlusion is typically attributed to technical factors. We aimed at exploring clinical, anatomical, and operative factors associated with the risk of early SVG occlusion (within 12 months postsurgery). Methods: Published literature in MEDLINE was searched for studies reporting the incidence of early SVG occlusion. Individual patient data (IPD) on early SVG occlusion were used from the SAFINOUS-CABG Consortium. A derivation (n = 1492 patients) and validation (n = 372 patients) cohort were used for model training (with 10-fold cross-validation) and external validation respectively. Results: In aggregate data meta-analysis (48 studies, 41,530 SVGs) the pooled estimate for early SVG occlusion was 11%. The developed IPD model for early SVG occlusion, which included clinical, anatomical, and operative characteristics (age, sex, dyslipidemia, diabetes mellitus, smoking, serum creatinine, endoscopic vein harvesting, use of complex grafts, grafted target vessel, and number of SVGs), had good performance in the derivation (c-index = 0.744; 95% confidence interval [CI], 0.701-0.774) and validation cohort (c-index = 0.734; 95% CI, 0.659-0.809). Based on this model. we constructed a simplified 12-variable risk score system (SAFINOUS score) with good performance for early SVG occlusion (c-index = 0.700, 95% CI, 0.684-0.716). Conclusions: From a large international IPD collaboration, we developed a novel risk score to assess the individualized risk for early SVG occlusion. The SAFINOUS risk score could be used to identify patients that are more likely to benefit from aggressive treatment strategies
A Biobrick Library for Cloning Custom Eukaryotic Plasmids
Researchers often require customised variations of plasmids that are not commercially available. Here we demonstrate the applicability and versatility of standard synthetic biological parts (biobricks) to build custom plasmids. For this purpose we have built a collection of 52 parts that include multiple cloning sites (MCS) and common protein tags, protein reporters and selection markers, amongst others. Importantly, most of the parts are designed in a format to allow fusions that maintain the reading frame. We illustrate the collection by building several model contructs, including concatemers of protein binding-site motifs, and a variety of plasmids for eukaryotic stable cloning and chromosomal insertion. For example, in 3 biobrick iterations, we make a cerulean-reporter plasmid for cloning fluorescent protein fusions. Furthermore, we use the collection to implement a recombinase-mediated DNA insertion (RMDI), allowing chromosomal site-directed exchange of genes. By making one recipient stable cell line, many standardised cell lines can subsequently be generated, by fluorescent fusion-gene exchange. We propose that this biobrick collection may be distributed peer-to-peer as a stand-alone library, in addition to its distribution through the Registry of Standard Biological Parts (http://partsregistry.org/)
A Novel Replication-Competent Vaccinia Vector MVTT Is Superior to MVA for Inducing High Levels of Neutralizing Antibody via Mucosal Vaccination
Mucosal vaccination offers great advantage for inducing protective immune response to prevent viral transmission and dissemination. Here, we report our findings of a head-to-head comparison of two viral vectors modified vaccinia Ankara (MVA) and a novel replication-competent modified vaccinia Tian Tan (MVTT) for inducing neutralizing antibodies (Nabs) via intramuscular and mucosal vaccinations in mice. MVTT is an attenuated variant of the wild-type VTT, which was historically used as a smallpox vaccine for millions of Chinese people. The spike glycoprotein (S) of SARS-CoV was used as the test antigen after the S gene was constructed in the identical genomic location of two vectors to generate vaccine candidates MVTT-S and MVA-S. Using identical doses, MVTT-S induced lower levels (∼2-3-fold) of anti- SARS-CoV neutralizing antibodies (Nabs) than MVA-S through intramuscular inoculation. MVTT-S, however, was capable of inducing consistently 20-to-100-fold higher levels of Nabs than MVA-S when inoculated via either intranasal or intraoral routes. These levels of MVTT-S-induced Nab responses were substantially (∼10-fold) higher than that induced via the intramuscular route in the same experiments. Moreover, pre-exposure to the wild-type VTT via intranasal or intraoral route impaired the Nab response via the same routes of MVTT-S vaccination probably due to the pre-existing anti-VTT Nab response. The efficacy of intranasal or intraoral vaccination, however, was still 20-to-50-fold better than intramuscular inoculation despite the subcutaneous pre-exposure to wild-type VTT. Our data have implications for people who maintain low levels of anti-VTT Nabs after historical smallpox vaccination. MVTT is therefore an attractive live viral vector for mucosal vaccination
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