The Influence of Formulation, Buffering, pH and Divalent Cations on the Activity of Endothall on Hydrilla.

Endothall has been used as an aquatic herbicide for more than 40 years and provides very effective weed control of many weeds. Early research regarding the mechanism-of-action of endothall contradicts the symptomology normally associated with the product. Recent studies suggest endothall is a respiratory toxin but the mechanism-of-action remains unknown. To further elucidate the activity of endothall, several endothall formulations were evaluated for their effects on ion leakage, oxygen consumption and photosynthetic oxygen evolution from hydrilla shoot tips. The influence of pH, buffering and divalent cations was also evaluated. (PDF contains 6 pages.

Vortex Matter Transition in Bi2{}_2Sr2{}_2CaCu2{}_2O8+y{}_{8+y} under Tilted Fields

Vortex phase diagram under tilted fields from the $c$ axis in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+y}$ is studied by local magnetization hysteresis measurements using Hall probes. When the field is applied at large angles from the $c$ axis, an anomaly ($H_p^\ast$) other than the well-known peak effect ($H_p$) are found at fields below $H_p$. The angular dependence of the field $H_p^\ast$ is nonmonotonic and clearly different from that of $H_p$ and depends on the oxygen content of the crystal. The results suggest existence of a vortex matter transition under tilted fields. Possible mechanisms of the transition are discussed.Comment: Revtex, 4 pages, some corrections are adde

Abrupt Change of Josephson Plasma Frequency at the Phase Boundary of the Bragg Glass in Bi_2Sr_2CaCu_2O_{8+\delta}

We report the first detailed and quantitative study of the Josephson coupling energy in the vortex liquid, Bragg glass and vortex glass phases of Bi_2Sr_2CaCu_2O_{8+\delta} by the Josephson plasma resonance. The measurements revealed distinct features in the T- and H-dependencies of the plasma frequency $\omega_{pl}$ for each of these three vortex phases. When going across either the Bragg-to-vortex glass or the Bragg-to-liquid transition line, $\omega_{pl}$ shows a dramatic change. We provide a quantitative discussion on the properties of these phase transitions, including the first order nature of the Bragg-to-vortex glass transition.Comment: 5pages, 4figure

Cloud droplet activation of mixed organic-sulfate particles produced by the photooxidation of isoprene

The cloud condensation nuclei (CCN) properties of ammonium sulfate particles mixed with organic material condensed during the hydroxyl-radical-initiated photooxidation of isoprene (C<sub>5</sub>H<sub>8</sub>) were investigated in the continuous-flow Harvard Environmental Chamber. CCN activation curves were measured for organic particle mass concentrations of 0.5 to 10.0 μg m<sup>−3</sup>, NO<sub>x</sub> concentrations from under 0.4 ppbv up to 38 ppbv, particle mobility diameters from 70 to 150 nm, and thermodenuder temperatures from 25 to 100 °C. At 25 °C, the observed CCN activation curves were accurately described by a Köhler model having two internally mixed components, namely ammonium sulfate and secondary organic material. The modeled physicochemical parameters of the organic material were equivalent to an effective hygroscopicity parameter κ<sub>ORG</sub> of 0.10±0.03, regardless of the C<sub>5</sub>H<sub>8</sub>:NO<sub>x</sub> concentration ratio for the span of >200:0.4 to 50:38 (ppbv:ppbv). The volatilization curves (i.e., plots of the residual organic volume fraction against temperature) were also similar for the span of investigated C<sub>5</sub>H<sub>8</sub>:NO<sub>x</sub> ratios, suggesting a broad similarity of particle chemical composition. This suggestion was supported by limited variance at 25 °C among the particle mass spectra. For example, the signal intensity at <i>m/z</i> 44 (which can result from the fragmentation of oxidized molecules believed to affect hygroscopicity and CCN properties) varied weakly from 6 to 9% across the range of investigated conditions. In contradistinction to the results for 25 °C, conditioning up to 100 °C in the thermodenuder significantly reduced CCN activity. The altered CCN activity might be explained by chemical reactions (e.g., decomposition or oligomerization) of the secondary organic material at elevated temperatures. The study's results at 25 °C, in conjunction with the results of other chamber and field studies for a diverse range of conditions, suggest that a value of 0.10±0.05 for κ<sub>ORG</sub> is representative of both anthropogenic and biogenic secondary organic material. This finding supports the use of κ<sub>ORG</sub> as a simplified yet accurate general parameter to represent the CCN activation of secondary organic material in large-scale atmospheric and climate models

Particle mass yield in secondary organic aerosol formed by the dark ozonolysis of α-pinene

The yield of particle mass in secondary organic aerosol (SOA) formed by dark ozonolysis was measured for 0.3–22.8 ppbv of reacted α-pinene. Most experiments were conducted using a continuous-flow chamber, allowing nearly constant SOA concentration and chemical composition for several days. For comparison, some experiments were also conducted in batch mode. Reaction conditions were 25°C, 40% RH, dry (NH<sub>4</sub>)SO<sub>4</sub> seed particles, and excess 1-butanol. The organic particle loading was independently measured by an aerosol mass spectrometer and a scanning mobility particle sizer, and the two measurements agreed well. The observations showed that SOA formation occurred for even the lowest reacted α-pinene concentration of 0.3 ppbv. The particle mass yield was 0.09 at 0.15 μg m<sup>−3</sup>, increasing to 0.27 at 40 μg m<sup>−3</sup>. Compared to some results reported in the literature, the yields were 80 to 100% larger for loadings above 2 μg m<sup>−3</sup>. At lower loadings, the yields had an offset of approximately +0.07 from those reported in the literature. To as low as 0.15 μm<sup>−3</sup>, the yield curve had no inflection point toward null yield, implying the formation of one or several products having vapor pressures below this value. These observations of increased yields, especially for low loadings, are potentially important for accurate prediction by chemical transport models of organic particle concentrations in the ambient atmosphere

Call Me Caitlyn: Making and making over the 'authentic' transgender body in Anglo-American popular culture

A conception of transgender identity as an ‘authentic’ gendered core ‘trapped’ within a mismatched corporeality, and made tangible through corporeal transformations, has attained unprecedented legibility in contemporary Anglo-American media. Whilst pop-cultural articulations of this discourse have received some scholarly attention, the question of why this 'wrong body' paradigm has solidified as the normative explanation for gender transition within the popular media remains underexplored. This paper argues that this discourse has attained cultural pre-eminence through its convergence with a broader media and commercial zeitgeist, in which corporeal alteration and maintenance are perceived as means of accessing one’s ‘authentic’ self. I analyse the media representations of two transgender celebrities: Caitlyn Jenner and Nadia Almada, alongside the reality TV show TRANSform Me, exploring how these women’s gender transitions have been discursively aligned with a cultural imperative for all women, cisgender or trans, to display their authentic femininity through bodily work. This demonstrates how established tropes of authenticity-via-bodily transformation, have enabled transgender to become culturally legible through the wrong body trope. Problematically, I argue, this process has worked to demarcate ideals of ‘acceptable’ transgender subjectivity: self-sufficient, normatively feminine, and eager to embrace the possibilities for happiness and social integration provided by the commercial domain

Beings in their own right? Exploring Children and young people's sibling and twin relationships in the Minority World

This paper examines the contributions that the sociological study of sibship and twinship in the Minority World can make to childhood studies. It argues that, in providing one forum within which to explore children and young people's social relationships, we can add to our understanding of children and young people's interdependence and develop a more nuanced understanding of agency. As emergent subjects, children, young people and adults are in a process of ‘becoming’. However, this does not mean that they can ‘become’ anything they choose to. The notion of negotiated interdependence (Punch 2002) is useful in helping us to grasp the contingent nature of children and young people's agency

EXPORTS North Atlantic eddy tracking

The EXPORTS North Atlantic field campaign (EXPORTS-NA) of May 2021 used a diverse array of ship-based and autonomous platforms to measure and quantify processes leading to carbon export in the open ocean. The success of this field program relied heavily on the ability to make measurements following a Lagrangian trajectory within a coherent, retentive eddy (Sections 1, 2). Identifying an eddy that would remain coherent and retentive over the course of a monthlong deployment was a significant challenge that the EXPORTS team faced. This report details the processes and procedures used by the primarily shore-based eddy tracking team to locate, track, and sample with autonomous assets such an eddy before and during EXPORTS-NA.This field deployment was funded by the NASA Ocean Biology and Biogeochemistry program and the National Science Foundation Biological and Chemical Oceanography programs. Initial gliders deployments were performed by the RRS Discovery and the authors thank the Porcupine Abyssal Plain – Sustained Observatory of the Natural Environment Research Council (NERC, UK), which is principally funded through the Climate Linked Atlantic Sector Science (CLASS) project supported by NERC National Capability funding (NE/R015953/1) and by IFADO (Innovation in the Framework of the Atlantic Deep Ocean) EAPA_165/2016. Technical assistance with glider deployment was provided by Marine Autonomous Robotic Systems (NOC). The authors thank Inia Soto Ramos for assistance in publishing this manuscript through the NASA Technical Memorandum series. This is PMEL contribution number 5372