571 research outputs found
Symmetry, singularities and integrability in complex dynamics III: approximate symmetries and invariants
The different natures of approximate symmetries and their corresponding first
integrals/invariants are delineated in the contexts of both Lie symmetries of
ordinary differential equations and Noether symmetries of the Action Integral.
Particular note is taken of the effect of taking higher orders of the
perturbation parameter. Approximate symmetries of approximate first
integrals/invariants and the problems of calculating them using the Lie method
are considered
Report from the field - Overview of the Sixth Annual Vaccine Renaissance Conference
The Sixth Annual Vaccine Renaissance Conference, hosted by the Institute for Immunology and Informatics (iCubed) at the University of Rhode Island (URI), took place on October 15–17, 2012. This conference provides a forum for the review of current progress in the discovery and development of vaccines, and creates an environment for the exchange of ideas. Dr. Joel McCleary opened the conference with a warning about the importance of preparing for well-defined biowarfare threats, including tularemia and Staphylococcal enterotoxin B. Following the keynote address, sessions explored biodefense and preparation for pandemic and biowarfare threats; vaccines for emerging and re-emerging neglected tropical diseases; animal vaccines and human health; and vaccine vectors and the human microbiome. In this issue of Human Vaccines and Immunotherapeutics, seven Vaccine Renaissance Conference speakers will showcase their work; here, we describe a few of the conference highlights
Progress in Interferometry for LISA at JPL
Recent advances at JPL in experimentation and design for LISA interferometry
include the demonstration of Time Delay Interferometry using electronically
separated end stations, a new arm-locking design with improved gain and
stability, and progress in flight readiness of digital and analog electronics
for phase measurements.Comment: 11 pages, 9 figures, LISA 8 Symposium, Stanford University, 201
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Experimental determination of carbonate-associated sulfate δ^(34)S in planktonic foraminifera shells
Understanding the coupling of oxygen, carbon, and sulfur cycles in the past is critical for reconstructing the history of biogeochemical cycles, paleoclimatic variations, and oceanic chemistry. The abundance of sulfur isotopes (δ^(34)S) in sulfate from ancient marine carbonates, or carbonate-associated sulfate (CAS), is commonly used, along with other archives (mainly evaporites and barite), to estimate the δ^(34)S of seawater throughout Earth history. Analyses of CAS from hand-picked foraminifera are potentially valuable because this group of organisms is used in numerous paleoceanographic studies. They could provide coupled, high-resolution records of δ^(13)C, δ^(18)O, and δ^(34)S isotopic changes directly linked to orbitally tuned records of climate change through the Cenozoic. Such measurements have not previously been possible due to limitations of sensitivity in conventional IRMS-based techniques. However, the recent development of CAS analysis by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) now allows us to work on samples containing just a few nmol of sulfur with accuracy for δ^(34)S values approaching 0.1‰ and, consequently, to analyze hand-picked samples of foraminifera shells. Here we report the results of culture experiments with the planktonic species Orbulina universa, that establish a shell:seawater δ^(34)S calibration for future applications to the fossil record. Our new method uses <650 μg of carbonate (∼15 shells) per analysis. The results show that S isotopes are fractionated consistently by −1‰ between seawater and O. universa tests. We also demonstrate that O. universa faithfully records the [SO^(2−)_(4)]/[Ca^(2+)] ratio of the seawater in which it grew
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Impact of rabies vaccination history on attainment of an adequate antibody titre among dogs tested for International Travel Certification, Israel - 2010-2014
Rabies is endemic in wildlife or domestic carnivore populations globally. Infection of domestic dogs is of particular concern in many areas. In regions where domestic animals are at risk of exposure to rabies virus, dogs should be routinely vaccinated against rabies to protect both pet and human populations. Many countries require demonstration of an adequate level of serum rabies neutralizing antibodies to permit entry of dogs during international travel. We analysed rabies titres of dogs seeking travel certification in Israel to assess demographic and vaccine history factors associated with antibody titres below the acceptable threshold for travel certification. Having received only one previous rabies vaccination and a longer duration since the most recent vaccination was received were primary risk factors for not achieving an adequate rabies virus neutralizing antibody titre for travel certification. These risk factors had stronger effects in younger animals, but were consistent for dogs of all ages. In particular, these findings reiterate the importance of administering at least two rabies vaccinations (the primo vaccination and subsequent booster) to ensure population-level protection against rabies in dogs globally
Drones, Virtual Reality, and Modeling: Communicating Catastrophic Dam Failure
Dam failures occur worldwide and can be economically and ecologically devastating. Communicating the scale of these risks to the general public and decision-makers is imperative. Two-dimensional (2D) dam failure hydraulic models inform owners and floodplain managers of flood regimes but have limitations when shared with non-specialists. This study addresses these limitations by constructing a 3D Virtual Reality (VR) environment to display the 1976 Teton Dam disaster case study using a pipeline composed of (1) 2D hydraulic model data (extrapolated into 3D), (2) a 3D reconstructed dam, and (3) a terrain model processed from UAS (Uncrewed Airborne System) imagery using Structure from Motion photogrammetry. This study validates the VR environment pipeline on the Oculus Quest 2 VR Headset with the criteria: immersion fidelity, movement, immersive soundscape, and agreement with historical observations and terrain. Through this VR environment, we develop an effective method to share historical events and, with future work, improve hazard awareness; applications of this method could improve citizen engagement with Early Warning Systems. This paper establishes a pipeline to produce a visualization tool for merging UAS imagery, Virtual Reality, digital scene creation, and sophisticated 2D hydraulic models to communicate catastrophic flooding events from natural or human-made levees or dams
Modulator noise suppression in the LISA Time-Delay Interferometric combinations
We previously showed how the measurements of some eighteen time series of
relative frequency or phase shifts could be combined (1) to cancel the phase
noise of the lasers, (2) to cancel the Doppler fluctuations due to non-inertial
motions of the six optical benches, and (3) to remove the phase noise of the
onboard reference oscillators required to track the photodetector fringes, all
the while preserving signals from passinggravitational waves. Here we analyze
the effect of the additional noise due to the optical modulators used for
removing the phase fluctuations of the onboard reference oscillators. We use a
recently measured noise spectrum of an individual modulator to quantify the
contribution of modulator noise to the first and second-generation Time-Delay
Interferometric (TDI) combinations as a function of the modulation frequency.
We show that modulator noise can be made smaller than the expected proof-mass
acceleration and optical-path noises if the modulation frequencies are larger
than MHz in the case of the unequal-arm Michelson TDI combination
, GHz for the Sagnac TDI combination , and
MHz for the symmetrical Sagnac TDI combination . These
modulation frequencies are substantially smaller than previously estimated and
may lead to less stringent requirements on the LISA's oscillator noise
calibration subsystem.Comment: 17 pages, 5 figures. Submitted to: Phys. Rev. D 1
Decadal-centennial scale monsoon variations in the Arabian Sea during the Early Holocene
An essential prerequisite for the prediction of future climate change due to anthropogenic input is an understanding of the natural processes that control Earth's climate on timescales comparable to human-lifespan. The Early Holocene period was chosen to study the natural climate variability in a warm interval when solar insolation was at its maximum. The monsoonal system of the Tropics is highly sensitive to seasonal variations in solar insolation, and consequently marine sediments from the region are a potential monitor of past climate change. Here we show that during the Early Holocene period rapid
Immunogenic Consensus Sequence T Helper Epitopes for a Pan-Burkholderia Biodefense Vaccine
Background: Biodefense vaccines against Category B bioterror agents Burkholderia pseudomallei (BPM) and Burkholderia mallei (BM) are needed, as they are both easily accessible to terrorists and have strong weaponization potential. Burkholderia cepaciae (BC), a related pathogen, causes chronic lung infections in cystic fibrosis patients. Since BPM, BM and BC are all intracellular bacteria, they are excellent targets for T cell-based vaccines. However, the sheer volume of available genomic data requires the aid of immunoinformatics for vaccine design. Using EpiMatrix, ClustiMer and EpiAssembler, a set of immunoinformatic vac-cine design tools, we screened the 31 available Burkholderia genomes and performed initial tests of our selections that are candidates for an epitope-based multi-pathogen vaccine against Burkholderia species.
Results: Immunoinformatics analysis of 31 Burkholderia genomes yielded 350,004 9-mer candidate vaccine peptides of which 133,469 had perfect conservation across the 10 BM genomes, 175,722 had per-fect conservation across the 11 BPM genomes and 40,813 had perfect conservation across the 10 BC genomes. Further screening with EpiMatrix yielded 54,010 high-scoring Class II epitopes; these were assembled into 2,880 longer highly conserved ‘immunogenic consensus sequence’ T helper epitopes. 100% of the peptides bound to at least one HLA class II allele in vitro, 92.7% bound to at least two alleles, 82.9% to three, and 75.6% of the binding results were consistent with the immunoinformatics analysis.
Conclusions: Our results show it is possible to rapidly identify promiscuous T helper epitopes conserved across multiple Burkholderia species and test their binding to HLA ligands in vitro. The next step in our process will be to test the epitopes ex vivo using peripheral leukocytes from BC, BPM infected humans and for immunogenicity in human HLA transgenic mice. We expect that this approach will lead to development of a licensable, pan-Burkholderia biodefense vaccine
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