Theory of post-block 2 VLBI observable extraction

The algorithms used in the post-Block II fringe-fitting software called 'Fit' are described. The steps needed to derive the very long baseline interferometry (VLBI) charged-particle corrected group delay, phase delay rate, and phase delay (the latter without resolving cycle ambiguities) are presented beginning with the set of complex fringe phasors as a function of observation frequency and time. The set of complex phasors is obtained from the JPL/CIT Block II correlator. The output of Fit is the set of charged-particle corrected observables (along with ancillary information) in a form amenable to the software program 'Modest.

Statistical Studies of Giant Pulse Emission from the Crab Pulsar

We have observed the Crab pulsar with the Deep Space Network (DSN) Goldstone 70 m antenna at 1664 MHz during three observing epochs for a total of 4 hours. Our data analysis has detected more than 2500 giant pulses, with flux densities ranging from 0.1 kJy to 150 kJy and pulse widths from 125 ns (limited by our bandwidth) to as long as 100 microseconds, with median power amplitudes and widths of 1 kJy and 2 microseconds respectively. The most energetic pulses in our sample have energy fluxes of approximately 100 kJy-microsecond. We have used this large sample to investigate a number of giant-pulse emission properties in the Crab pulsar, including correlations among pulse flux density, width, energy flux, phase and time of arrival. We present a consistent accounting of the probability distributions and threshold cuts in order to reduce pulse-width biases. The excellent sensitivity obtained has allowed us to probe further into the population of giant pulses. We find that a significant portion, no less than 50%, of the overall pulsed energy flux at our observing frequency is emitted in the form of giant pulses.Comment: 19 pages, 17 figures; to be published in Astrophysical Journa

The San Antonio River Mammoth Site: Archaeological Testing Investigations for the Interstate 37 Bridge at the San Antonio River Improvement Project, Bexar County, Texas

On behalf of the Texas Department of Transportation (TxDOT), SWCA Environmental Consultants (SWCA) conducted test excavations on the San Antonio River Mammoth site (41BX1239) and 41BX1240 and surveys in the area of potential effects (APE) of the Interstate Highway (IH) 37 bridge project at the San Antonio River in southeastern Bexar County, Texas. Work was initiated to address the requirements of Section 106 of the National Historic Preservation Act (1966) as Amended and the Antiquities Code of Texas. The purpose of the investigations was to identify, delineate, and evaluate the significance of all archaeological and historic properties potentially affected by the undertaking and, if warranted, recommend the scope of additional work. Of particular concern, site 41BX1239 contains the remains of at least two mammoths with possible evidence of cultural association based on the initial investigations by Texas A&M in 1997. However, subsequent faunal analysis, conducted by Olga Potapova and Larry D. Agenbroad of the Mammoth Site in Hot Springs, North Dakota, found inconclusive evidence for definite or valid cultural modification to the specimens studied. The testing investigations on the San Antonio River Mammoth site included the re-exposure of the original Texas A&M 1997 site trench; limited hand-excavated units to further assess the prior interpretations of the deposits and recover a sample of bone; and a detailed geomorphological assessment. The work identified a bone bed consisting of the remains of at least two mammoths. Flotation of recovered sediments from these hand excavations identified flakes of siliceous material that are consistent with micro-debitage produced by the use and retouch of stone tools. Although at the highest thresholds of certainty, the cumulative evidence is likely yet insufficient to conclusively prove human interaction with the mammoth remains, the additional data gathered herein lend some credence to the prior interpretation of the site as archaeological rather than strictly paleontological. Concurring with the previous determination, the site is considered eligible for inclusion to the National Register of Historic Places (NRHP) and for listing as a State Archeological Landmark (SAL). However, the investigations determined the site deposits are located outside the APE of the current undertaking, and therefore the project will not affect deposits associated with the San Antonio River Mammoth site. The investigations of 41BX1240 identified only a very sparse scatter of primarily surficial materials in a heavily disturbed context with no associated features or diagnostic materials. Accordingly, the site is not recommended as eligible for listing on the NRHP or for designation as a SAL. The survey identified no new archaeological sites. Based on the avoidance of 41BX1239, it is SWCA’s recommendation that no archaeological properties will be affected by the IH 37 bridge rehabilitation

Host–Guest Hybrid Redox Materials Self‐Assembled from Polyoxometalates and Single‐Walled Carbon Nanotubes

The development of next‐generation molecular‐electronic, electrocatalytic, and energy‐storage systems depends on the availability of robust materials in which molecular charge‐storage sites and conductive hosts are in intimate contact. It is shown here that electron transfer from single‐walled carbon nanotubes (SWNTs) to polyoxometalate (POM) clusters results in the spontaneous formation of host–guest POM@SWNT redox‐active hybrid materials. The SWNTs can conduct charge to and from the encapsulated guest molecules, allowing electrical access to >90% of the encapsulated redox species. Furthermore, the SWNT hosts provide a physical barrier, protecting the POMs from chemical degradation during charging/discharging and facilitating efficient electron transfer throughout the composite, even in electrolytes that usually destroy POMs

TIMED Imaging Photometer Experiment (TIPE)

This document contains a summary of the TIMED Imaging Photometer Experiment (TIPE) instrument study at the time of the termination of project due to TIPE being de-selected from the Thermosphere, Ionosphere and Mesosphere Energetics and Dynamics (TIMED) mission

Ageing-associated DNA methylation dynamics are a molecular readout of lifespan variation among mammalian species.

BACKGROUND: Mammalian species exhibit a wide range of lifespans. To date, a robust and dynamic molecular readout of these lifespan differences has not yet been identified. Recent studies have established the existence of ageing-associated differentially methylated positions (aDMPs) in human and mouse. These are CpG sites at which DNA methylation dynamics show significant correlations with age. We hypothesise that aDMPs are pan-mammalian and are a dynamic molecular readout of lifespan variation among different mammalian species. RESULTS: A large-scale integrated analysis of aDMPs in six different mammals reveals a strong negative relationship between rate of change of methylation levels at aDMPs and lifespan. This relationship also holds when comparing two different dog breeds with known differences in lifespans. In an ageing cohort of aneuploid mice carrying a complete copy of human chromosome 21, aDMPs accumulate far more rapidly than is seen in human tissues, revealing that DNA methylation at aDMP sites is largely shaped by the nuclear trans-environment and represents a robust molecular readout of the ageing cellular milieu. CONCLUSIONS: Overall, we define the first dynamic molecular readout of lifespan differences among mammalian species and propose that aDMPs will be an invaluable molecular tool for future evolutionary and mechanistic studies aimed at understanding the biological factors that determine lifespan in mammals

Development and validation of a high density SNP genotyping array for Atlantic salmon (Salmo salar)

BackgroundDense single nucleotide polymorphism (SNP) genotyping arrays provide extensive information on polymorphic variation across the genome of species of interest. Such information can be used in studies of the genetic architecture of quantitative traits and to improve the accuracy of selection in breeding programs. In Atlantic salmon (Salmo salar), these goals are currently hampered by the lack of a high-density SNP genotyping platform. Therefore, the aim of the study was to develop and test a dense Atlantic salmon SNP array. ResultsSNP discovery was performed using extensive deep sequencing of Reduced Representation (RR-Seq), Restriction site-Associated DNA (RAD-Seq) and mRNA (RNA-Seq) libraries derived from farmed and wild Atlantic salmon samples (n = 283) resulting in the discovery of > 400 K putative SNPs. An Affymetrix Axiom® myDesign Custom Array was created and tested on samples of animals of wild and farmed origin (n = 96) revealing a total of 132,033 polymorphic SNPs with high call rate, good cluster separation on the array and stable Mendelian inheritance in our sample. At least 38% of these SNPs are from transcribed genomic regions and therefore more likely to include functional variants. Linkage analysis utilising the lack of male recombination in salmonids allowed the mapping of 40,214 SNPs distributed across all 29 pairs of chromosomes, highlighting the extensive genome-wide coverage of the SNPs. An identity-by-state clustering analysis revealed that the array can clearly distinguish between fish of different origins, within and between farmed and wild populations. Finally, Y-chromosome-specific probes included on the array provide an accurate molecular genetic test for sex. ConclusionsThis manuscript describes the first high-density SNP genotyping array for Atlantic salmon. This array will be publicly available and is likely to be used as a platform for high-resolution genetics research into traits of evolutionary and economic importance in salmonids and in aquaculture breeding programs via genomic selection

Stochastic Simulation Methods Applied to a Secure Electronic Voting Model

We demonstrate a novel simulation technique for analysing large stochastic process algebra models, applying this to a secure electronic voting system example. By approximating the discrete state space of a PEPA model by a continuous equivalent, we can draw on rate equation simulation techniques from both chemical and biological modelling to avoid having to directly enumerate the huge state spaces involved. We use stochastic simulation techniques to provide traces of course-of-values time series representing the number of components in a particular state. Using such a technique we can get simulation results for models exceeding 10 10000 states within only a few seconds