3,963 research outputs found
Block-by-Block: Leveraging the Power of Blockchain Technology to Build Trust and Promote Cyber Peace
There has been increasing interest in the transformative power of not only crypto-currencies like Bitcoin, but also the technology underlying them-namely blockchain. To the uninitiated, a blockchain is a sophisticated, distributed online ledger that has the potential, according to Goldman Sachs, to change \u27everything. \u27 From making businesses more efficient to recording property deeds to engendering the growth of \u27smart\u27 contracts, blockchain technology is now being investigated by a huge range of organizations and is attracting billions in venture funding. Even the U.S. Defense Advanced Research Projects Agency (DARPA) is investigating blockchain technology to create an unhackable messaging system
Intelligent assistance in scientific data preparation
Scientific data preparation is the process of extracting usable scientific data from raw instrument data. This task involves noise detection (and subsequent noise classification and flagging or removal), extracting data from compressed forms, and construction of derivative or aggregate data (e.g. spectral densities or running averages). A software system called PIPE provides intelligent assistance to users developing scientific data preparation plans using a programming language called Master Plumber. PIPE provides this assistance capability by using a process description to create a dependency model of the scientific data preparation plan. This dependency model can then be used to verify syntactic and semantic constraints on processing steps to perform limited plan validation. PIPE also provides capabilities for using this model to assist in debugging faulty data preparation plans. In this case, the process model is used to focus the developer's attention upon those processing steps and data elements that were used in computing the faulty output values. Finally, the dependency model of a plan can be used to perform plan optimization and run time estimation. These capabilities allow scientists to spend less time developing data preparation procedures and more time on scientific analysis tasks
Optical spectroscopy of radio galaxies in the 7C Redshift Survey
We present optical spectroscopy of all 49 radio galaxies in the 7C-I and
7C-II regions of the 7C Redshift Survey (7CRS). The low-frequency (151 MHz)
selected 7CRS sample contains all sources with flux-densities S_151 > 0.5 Jy in
three regions of the sky; 7C-I and 7C-II were chosen to overlap with the 5C6
and 5C7 surveys respectively, and cover a total sky area of 0.013 sr. The
sample has been completely identified and spectroscopy of the quasars and
broad-lined radio galaxies has been presented in Willott et al. (1998). Only
seven of the radio galaxies do not have redshift determinations from the
spectroscopy, giving a redshift completeness for the sample of >90%. The median
redshift of the 7CRS is 1.1. We present a composite 0.2<z<0.8 7CRS radio galaxy
spectrum and investigate the strengths of the 4000 Angstrom breaks in these
radio galaxies. We find an anti-correlation between the 4000 Angstrom break
strength and emission line luminosity, indicating that departures from old
elliptical galaxy continuum shapes are most likely due to non-stellar emission
associated with the active nucleus.Comment: 14 pages, 6 figures, MNRAS in pres
Short-term Osteoclastic Activity Induced by Locally High Concentrations of Recombinant Human Bone Morphogenetic Proteinâ2 in a Cancellous Bone Environment
Study Design. An experimental study investigating osteoclastic activity induced by rhBMP-2 in sheep.
Objective. To examine the effects of increasing local rhBMP-2 concentration on osteoclastic response and peri-implant bone resorption.
Summary of Background Data. Level I clinical studies have established the safe and effective volume and concentration of rhBMP-2 delivered on an absorbable collagen sponge. However, peri-implant bone resorption appearing as decreased mineral density has been observed radiographically in rare instances after implantation of rhBMP-2 on an absorbable collagen sponge (rhBMP-2/ACS).
Methods. Bilateral corticocancellous defects were created in the distal femora of 30 adult sheep. Combinations of rhBMP-2/ACS implant volume (V) (1V = normal fill or 2V = overfilled) and rhBMP-2 solution concentration (‫) (1 ‫ normal concentration or 3.5 ‫ = hyperconcentrated) resulted in local rhBMP-2 concentrations of 0‫, 1‫, 2‫, 3.5‫, and 7‫ the estimated effective concentration for this model. Faxitron radiography, quantitative CT, histology, and quantitative
histomorphometry were conducted in a blinded fashion to analyze the effect of the treatments.
Results. At 1 week, the normal fill-normal concentration implants (1‫) produced the least transient osteoclastic activity resulting in limited peri-implant resorption. Overfilledhyperconcentrated implants (2‫, 3.5‫) demonstrated moderate resorption zones. Overfilled-hyperconcentrated implants (7‫) demonstrated extensive osteoclastic activity and marked resorption. Results at 4 and 8 weeks revealed dense osteoid and bone in the voids with progressive bony healing. Control defects showed no osteoclastic activity with little to no bony healing.
Conclusion. Increasing the local rhBMP-2 concentration by overfilling the defect with rhBMP-2/ACS or hyper-concentrating the rhBMP-2 solution on the absorbable collagen sponge led to a concentration-dependent osteoclastic resorption of peri-implant bone. The osteoclastic effect was transient, and progressive healing took place over the 8-week survival period
Voltage gated inter-cation selective ion channels from graphene nanopores
With the ability to selectively control ionic flux, biological protein ion
channels perform a fundamental role in many physiological processes. For
practical applications that require the functionality of a biological ion
channel, graphene provides a promising solid-state alternative, due to its
atomic thinness and mechanical strength. Here, we demonstrate that nanopores
introduced into graphene membranes, as large as 50 nm in diameter, exhibit
inter-cation selectivity with a ~20x preference for K+ over divalent cations
and can be modulated by an applied gate voltage. Liquid atomic force microscopy
of the graphene devices reveals surface nanobubbles near the pore to be
responsible for the observed selective behavior. Molecular dynamics simulations
indicate that translocation of ions across the pore likely occurs via a thin
water layer at the edge of the pore and the nanobubble. Our results demonstrate
a significant improvement in the inter-cation selectivity displayed by a
solid-state nanopore device and by utilizing the pores in a de-wetted state,
offers an approach to fabricating selective graphene membranes that does not
rely on the fabrication of sub-nm pores
Reaching the Diffraction Limit - Differential Speckle and Wide-Field Imaging for the Gemini-N Telescope
Speckle imaging allows telescopes to achieve di raction limited imaging performance. The technique requires cameras capable of reading out frames at a very fast rate, e ectively `freezing out' atmospheric seeing. The resulting speckles can be correlated and images reconstructed that are at the di raction limit of the telescope. These new instruments are based on the successful performance and design of the Di erential Speckle Survey Instrument (DSSI) [2, 1]. The instruments are being built for the Gemini-N and WIYN telescopes and will be made available to the community via the peer review proposal process. We envision their primary use to be validation and characterization of exoplanet targets from the NASA K2 and TESS missions and RV discovered exoplanets. Such targets will provide excellent follow-up candidates for both the WIYN and Gemini telescopes [3]. Examples of DSSI data are shown in the gures below. We expect similar data quality in speckle imaging mode with the new instruments. Additionally, both cameras will have a wide- eld mode and standard SDSS lters. They will be highly versatile instruments and it is that likely many other science programs will request time on the cameras. The limiting magnitude for speckle observations, will remain around 13-14th at WIYN and 16-17th at Gemini, while wide- eld, normal CCD imaging operation should be able to go to much fainter, providing usual CCD imaging and photometric capabilities. The instruments will also have high utility as scoring cameras for telescope engineering purposes, or other applications where high time resolution is needed. Instrument support will be provided, including a software pipeline that takes raw speckle data to fully reconstructed images
Reaching the Diffraction Limit - Differential Speckle and Wide-Field Imaging for the WIYN Telescope
Speckle imaging allows telescopes to achieve diffraction limited imaging performance. The technique requires cameras capable of reading out frames at a very fast rate, effectively 'freezing out' atmospheric seeing. The resulting speckles can be correlated and images reconstructed that are at the diffraction limit of the telescope. These new instruments are based on the successful performance and design of the Differential Speckle Survey Instrument (DSSI).The instruments are being built for the Gemini-N and WIYN telescopes and will be made available to the community via the peer review proposal process. We envision their primary use to be validation and characterization of exoplanet targets from the NASA, K2 and TESS missions and RV discovered exoplanets. Such targets will provide excellent follow-up candidates for both the WIYN and Gemini telescopes. We expect similar data quality in speckle imaging mode with the new instruments. Additionally, both cameras will have a wide-field mode and standard SDSS filters. They will be highly versatile instruments and it is that likely many other science programs will request time on the cameras. The limiting magnitude for speckle observations will remain around 13-14th at WIYN and 16-17th at Gemini, while wide-field, normal CCD imaging operation should be able to go to much fainter, providing usual CCD imaging and photometric capabilities. The instruments will also have high utility as scoring cameras for telescope engineering purposes, or other applications where high time resolution is needed. Instrument support will be provided, including a software pipeline that takes raw speckle data to fully reconstructed images
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Effects of carbon dioxide on the searching behaviour of the root-feeding clover weevil <i>Sitona lepidus</i> (Coleoptera: Curculionidae)
The respiratory emission of CO2 from roots is frequently proposed as an attractant that allows soil-dwelling insects to locate host plant roots, but this role has recently become less certain. CO2 is emitted from many sources other than roots, so does not necessarily indicate the presence of host plants, and because of the high density of roots in the upper soil layers, spatial gradients may not always be perceptible by soil-dwelling insects. The role of CO2 in host location was investigated using the clover root weevil Sitona lepidus Gyllenhall and its host plant white clover (Trifolium repens L.) as a model system. Rhizochamber experiments showed that CO2 concentrations were approximately 1000 ppm around the roots of white clover, but significantly decreased with increasing distance from roots. In behavioural experiments, no evidence was found for any attraction by S. lepidus larvae to point emissions of CO2, regardless of emission rates. Fewer than 15% of larvae were attracted to point emissions of CO2, compared with a control response of 17%. However, fractal analysis of movement paths in constant CO2 concentrations demonstrated that searching by S. lepidus larvae significantly intensified when they experienced CO2 concentrations similar to those found around the roots of white clover (i.e. 1000 ppm). It is suggested that respiratory emissions of CO2 may act as a âsearch triggerâ for S. lepidus, whereby it induces larvae to search a smaller area more intensively, in order to detect location cues that are more specific to their host plant.<br/
Securing the Internet of Healthcare
Cybersecurity, which includes the security of information technology (IT), is critical to ensuring that society trusts, and therefore can benefit from, modern technology. Problematically, though, rarely a day goes by without a news story related to how critical data has been exposed, exfiltrated, or otherwise inappropriately used or accessed as a result of supply chain vulnerabilities. From the Russian governmentâs campaign to influence the 2016 U.S. presidential election to the September 2017 Equifax breach of more than 140 million Americansâ credit reports, cyber risk has become a topic of conversation in boardrooms and the White House, on Wall Street and main street. But these discussions often miss the problems replete in the expansive supply chains on which many of these products and services we depend on are built; this is particularly true in the medical device context. The problem recently made national news with the voluntary recall of more than 400,000 pacemakers that were found to be vulnerable to hackers, necessitating a firmware update. This Article explores the myriad vulnerabilities in the supply chain for medical devices, investigates existing FDA cybersecurity and privacy regulations to identify any potential governance gaps, and suggests a path forward to boost cybersecurity due diligence for manufacturers by making use of new approaches and technologies, including blockchain
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