Unexpected evolutionary proximity of eukaryotic and cyanobacterial enzymes responsible for biosynthesis of retinoic acid and its oxidation

Biosynthesis of retinoic acid from retinaldehyde (retinal) is catalysed by an aldehyde dehydrogenase (ALDH) and its oxidation by cytochrome P450 enzymes (CYPs). Herein we show by phylogenetic analysis that the ALDHs and CYPs in the retinoic acid pathway in animals are much closer in evolutionary terms to cyanobacterial orthologs than would be expected from the standard models of evolution

Using the Ca II Triplet to Trace Abundance Variations in Individual Red Giant Branch stars in Three Nearby Galaxies

Spectroscopic abundance determinations for stars spanning a Hubble time in age are necessary in order to unambiguously determine the evolutionary histories of galaxies. Using FORS1 in Multi-Object Spectroscopy mode on ANTU (UT1) at the ESO-VLT on Paranal we obtained near infrared spectra from which we measured the equivalent widths of the two strongest Ca II triplet lines to determine metal abundances for a sample of Red Giant Branch stars, selected from ESO-NTT optical (I, V-I) photometry of three nearby, Local Group, galaxies: the Sculptor Dwarf Spheroidal, the Fornax Dwarf Spheroidal and the Dwarf Irregular NGC 6822. The summed equivalent width of the two strongest lines in the Ca II triplet absorption line feature, centered at 8500A, can be readily converted into an [Fe/H] abundance using the previously established calibrations by Armandroff & Da Costa (1991) and Rutledge, Hesser & Stetson (1997). We measured metallicities for 37 stars in Sculptor, 32 stars in Fornax, and 23 stars in NGC 6822, yielding more precise estimates of the metallicity distribution functions for these galaxies than it is possible to obtain photometrically. In the case of NGC 6822, this is the first direct measurement of the abundances of the intermediate-age and old stellar populations. We find metallicity spreads in each galaxy which are broadly consistent with the photometric width of the Red Giant Branch, although the abundances of individual stars do not always appear to correspond to their colour. This is almost certainly predominantly due to a highly variable star formation rate with time in these galaxies, which results in a non-uniform, non-globular-cluster-like, evolution of the Ca/Fe ratio.Comment: Accepted for publication in MNRA

Crucible of the Civil War: Virginia from Secession to Commemoration

Crucible of the Civil War offers an illuminating portrait of the state’s wartime economic, political, and social institutions. Weighing in on contentious issues within established scholarship while also breaking ground in areas long neglected by scholars, the contributors examine such concerns as the war’s effect on slavery in the state, the wartime intersection of race and religion, and the development of Confederate social networks. They also shed light on topics long disputed by historians, such as Virginia’s decision to secede from the Union, the development of Confederate nationalism, and how Virginians chose to remember the war after its close.https://scholarship.richmond.edu/bookshelf/1258/thumbnail.jp

An investigation of the formation and line properties of MgH in 3D hydrodynamical model stellar atmospheres

Studies of the isotopic composition of magnesium in cool stars have so far relied upon the use of one-dimensional (1D) model atmospheres. Since the isotopic ratios derived are based on asymmetries of optical MgH lines, it is important to test the impact from other effects affecting line asymmetries, like stellar convection. Here, we present a theoretical investigation of the effects of including self-consistent modeling of convection. Using spectral syntheses based on 3D hydrodynamical CO$^5$BOLD models of dwarfs (4000K$\lesssim T_\mathrm{eff}\lesssim5160K$, $4.0\leq$log(g)$\leq4.5$, $-3.0\leq[\mathrm{Fe/H}]\leq-1.0$) and giants ($T_\mathrm{eff}\sim4000$K, log(g)$=1.5$, $-3.0\leq[\mathrm{Fe/H}]\leq-1.0$), we perform a detailed analysis comparing 3D and 1D syntheses. We describe the impact on the formation and behavior of MgH lines from using 3D models, and perform a qualitative assessment of the systematics introduced by the use of 1D syntheses. Using 3D model atmospheres significantly affect the strength of the MgH lines, especially in dwarfs, with 1D syntheses requiring an abundance correction of up to +0.69 dex largest for our 5000K models. The corrections are correlated with $T_\mathrm{eff}$ and are also affected by the metallicity. The shape of the strong $^{24}$MgH component in the 3D syntheses is poorly reproduced in 1D. This results in 1D syntheses underestimating $^{25}$MgH by up to $\sim5$ percentage points and overestimating $^{24}$MgH by a similar amount for dwarfs. This discrepancy increases with decreasing metallicity. $^{26}$MgH is recovered relatively well, with the largest difference being $\sim2$ percentage points. The use of 3D for giants has less impact, due to smaller differences in the atmospheric structure and a better reproduction of the line shape in 1D.Comment: 20 pages, 15 figures, accepted for publication in Ap

Divergent discourse between protests and counter-protests: #BlackLivesMatter and #AllLivesMatter

Since the shooting of Black teenager Michael Brown by White police officer Darren Wilson in Ferguson, Missouri, the protest hashtag #BlackLivesMatter has amplified critiques of extrajudicial killings of Black Americans. In response to #BlackLivesMatter, other Twitter users have adopted #AllLivesMatter, a counter-protest hashtag whose content argues that equal attention should be given to all lives regardless of race. Through a multi-level analysis of over 860,000 tweets, we study how these protests and counter-protests diverge by quantifying aspects of their discourse. We find that #AllLivesMatter facilitates opposition between #BlackLivesMatter and hashtags such as #PoliceLivesMatter and #BlueLivesMatter in such a way that historically echoes the tension between Black protesters and law enforcement. In addition, we show that a significant portion of #AllLivesMatter use stems from hijacking by #BlackLivesMatter advocates. Beyond simply injecting #AllLivesMatter with #BlackLivesMatter content, these hijackers use the hashtag to directly confront the counter-protest notion of “All lives matter.” Our findings suggest that Black Lives Matter movement was able to grow, exhibit diverse conversations, and avoid derailment on social media by making discussion of counter-protest opinions a central topic of #AllLivesMatter, rather than the movement itself

Physical and mechanical properties of phosphonium based poly(ionic liquids)

Currently for applications in materials science, there is a growing interest in Ionogels i.e. polymers with ionic liquids (ILs) integrated such that they retain their specific properties within the polymer/gel environment. However one disadvantage of ionogels is the leaching of the IL in the liquid phase1. To overcome this, ‘poly (ionic liquids) PILs, are gaining momentum in the literature. Interesting applications for the incorporation of PILs into polymers have been published such as ultrasensitive and selective chemiresistive CO2 sensors2, and potential applications in fuel cell technology as some reported PIL films, display very high ionic conductivities (exceeding 90 mS cm-1 at 100 oC and 75% relative humidity)3. However the range of possible monomeric IL structures is far greater than has so far been explored4 In recent years functional materials have been developed to respond to a wide variety of stimuli, but their use in practical macro-scale devices has been hindered by slow response times arising mainly due to the diffusion processes that typically govern polymer swelling/contraction. The scaling-down to microfluidic devices should improve response times, due to the improved surface-to-volume ratios of these actuators. At these dimensions, stimuli-responsive PIL materials could dramatically enhance the capabilities of micro-fluidic systems by allowing self-regulated flow control. In this study we synthesis, characterise and photopattern a family of PILs, Tributyl 4-Vinylbenzylphosphonium ([P4,4,4,4VB]+ ), Trihexyl 4-Vinylbenzylphosphonium ([P6,6,6,4VB]+) and Trihexyl-allyl phosphonium [P6,6,6,allyl]+ cations coupled with commonly found anions in the ionic liquid literature (chloride, dicyanamide and bis(trifluoromethylsulfonyl)imide). As one might expect varying the anion of the PIL gave varying behaviour (thermal stability and electrochemically). The resulting polymer gels from the PILs also gave drastic mechanical stability differences. Finally the synthesised polymer gels have been photo-structured to submicron resolution as both planar and 3D patterns employing both single and multi- photon polymerisation (MPP) techniques. These materials will form a platform for the next generation of sensors & actuators currently being developed

Unconventional Josephson Effect in Hybrid Superconductor-Topological Insulator Devices

We report on transport properties of Josephson junctions in hybrid superconducting-topological insulator devices, which show two striking departures from the common Josephson junction behavior: a characteristic energy that scales inversely with the width of the junction, and a low characteristic magnetic field for suppressing supercurrent. To explain these effects, we propose a phenomenological model which expands on the existing theory for topological insulator Josephson junctions

HexPak and GradPak: variable-pitch dual-head IFUs for the WIYN 3.5m Telescope Bench Spectrograph

We describe the design, construction, and expected performance of two new fiber integral field units (IFUs) --- HexPak and GradPak --- for the WIYN 3.5m Telescope Nasmyth focus and Bench Spectrograph. These are the first IFUs to provide formatted fiber integral field spectroscopy with simultaneous sampling of varying angular scales. HexPak and GradPak are in a single cable with a dual-head design, permitting easy switching between the two different IFU heads on the telescope without changing the spectrograph feed: the two heads feed a variable-width double-slit. Each IFU head is comprised of a fixed arrangement of fibers with a range of fiber diameters. The layout and diameters of the fibers within each array are scientifically-driven for observations of galaxies: HexPak is designed to observe face-on spiral or spheroidal galaxies while GradPak is optimized for edge-on studies of galaxy disks. HexPak is a hexagonal array of 2.9 arcsec fibers subtending a 40.9 arcsec diameter, with a high-resolution circular core of 0.94 arcsec fibers subtending 6 arcsec diameter. GradPak is a 39 by 55 arcsec rectangular array with rows of fibers of increasing diameter from angular scales of 1.9 arcsec to 5.6 arcsec across the array. The variable pitch of these IFU heads allows for adequate sampling of light profile gradients while maintaining the photon limit at different scales.Comment: 10 pages, 4 figures, presented at SPIE, Astronomical Telescopes and Instrumentation, 1 - 6 July 2012, Amsterdam, Netherland

Assessing the vulnerability of plant functional trait strategies to climate change

Aim: Our ability to understand how species may respond to changing climate conditions is hampered by a lack of high-quality data on the adaptive capacity of species. Plant functional traits are linked to many aspects of species life history and adaptation to environment, with different combinations of trait values reflecting alternate strategies for adapting to varied conditions. If the realized climate limits of species can be partially explained by plant functional trait combinations, then a new approach of using trait combinations to predict the expected climate limits of species trait combinations may offer considerable benefits. Location: Australia. Time period: Current and future. Methods: Using trait data for leaf size, seed mass and plant height for 6,747 Australian native species from 27 plant families, we model the expected climate limits of trait combinations and use future climate scenarios to estimate climate change impacts based on plant functional trait strategies. Results: Functional trait combinations were a significant predictor of species climate niche metrics with potentially meaningful relationships with two rainfall variables (R2 =.36 &.45) and three temperature variables (R2 =.21,.28,.30). Using this method, the proportion of species exposed to conditions across their range that are beyond the expected climate limits of their trait strategies will increase under climate change. Main conclusions: Our new approach, called trait strategy vulnerability, includes three new metrics. For example, the climate change vulnerability (CCV) metric identified a small but important proportion of species (4.3%) that will on average be exposed to conditions beyond their expected limits for summer temperature in the future. These potentially vulnerable species could be high priority targets for deeper assessment of adaptive capacity at the genomic or physiological level. Our methods can be applied to any suite of co-occurring plants globally

Temperature & pH triggered release characteristics of water/fluorescein from 1-ethyl-3-methylimidazolium ethylsulfate based ionogels.

A crosslinked Poly(N-isopropylacrylamide) ionogel encapsulating an ionic liquid exhibits improved transmittance properties, enhanced water uptake/release, greater thermal actuation behaviour and distinct solvatomorphology over its hydrogel equivalent. It was also found that the rate of release of fluorescein pre-loaded into membranes was considerably enhanced for ionogels compared to equivalent hydrogels, and could be triggered through changes in pH and temperature