Chloroplast DNA and molecular phylogeny

The small, relatively constant size and conservative evolution of chloroplast DNA (cpDNA) make it an ideal molecule for tracing the evolutionary history of plant species. At lower taxonomic levels, cpDNA variation is easily and conveniently assayed by comparing restriction patterns and maps, while at higher taxonomic levels, DNA sequencing and inversion analysis are the methods of choice for comparing chloroplast genomes. The study of cpDNA variation has already yielded important new insights into the origin and evolution of many agriculturally important crop plants, and promises to significantly enhance our phylogenetic understanding of the major lines of descent among land plants and algae.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50180/1/950020607_ftp.pd

Reactivity of neodymium carriers in deep sea sediments: Implications for boundary exchange and paleoceanography

The dissolved neodymium (Nd) isotopic distribution in the deep oceans is determined by continental weathering inputs, water mass advection, and boundary exchange between particulate and dissolved fractions. Reconstructions of past Nd isotopic variability may therefore provide evidence on temporal changes in continental weathering inputs and/or ocean circulation patterns over a range of timescales. However, such an approach is limited by uncertainty in the mechanisms and importance of the boundary exchange process, and the challenge in reliably recovering past seawater Nd isotopic composition (εNd) from deep sea sediments. This study addresses these questions by investigating the processes involved in particulate–solution interactions and their impact on Nd isotopes. A better understanding of boundary exchange also has wider implications for the oceanic cycling and budgets of other particle-reactive elements. Sequential acid-reductive leaching experiments at pH ∼2–5 on deep sea sediments from the western Indian Ocean enable us to investigate natural boundary exchange processes over a timescale appropriate to laboratory experiments. We provide evidence that both the dissolution of solid phases and exchange processes influence the εNd of leachates, which suggests that both processes may contribute to boundary exchange. We use major element and rare earth element (REE) data to investigate the pools of Nd that are accessed and demonstrate that sediment leachate εNd values cannot always be explained by admixture between an authigenic component and the bulk detrital component. For example, in core WIND 24B, acid-reductive leaching generates εNd values between −11 and −6 as a function of solution/solid ratios and leaching times, whereas the authigenic components have εNd ≈ −11 and the bulk detrital component has εNd ≈ −15. We infer that leaching in the Mascarene Basin accesses authigenic components and a minor radiogenic volcanic component that is more reactive than Madagascan-derived clays. The preferential mobilisation of such a minor component demonstrates that the Nd released by boundary exchange could often have a significantly different εNd composition than the bulk detrital sediment. These experiments further demonstrate certain limitations on the use of acid-reductive leaching to extract the εNd composition of the authigenic fraction of bulk deep sea sediments. For example, the detrital component may contain a reactive fraction which is also acid-extractible, while the incongruent nature of this dissolution suggests that it is often inappropriate to use the bulk detrital sediment elemental chemistry and/or εNd composition when assessing possible detrital contamination of leachates. Based on the highly systematic controls observed, and evidence from REE patterns on the phases extracted, we suggest two approaches that lead to the most reliable extraction of the authigenic εNd component and good agreement with foraminiferal-based approaches; either (i) leaching of sediments without a prior decarbonation step, or (ii) the use of short leaching times and low solution/solid ratios throughout

An angle-scanned cryogenic Fabry-Pérot interferometer for far-infrared astronomy

The sensitivity of state-of-the-art superconducting far-infrared detectors used in conjunction with cryogenically cooled space telescopes and instrumentation is such that spectroscopic observations are generally limited by photon noise from the astronomical source or by galactic foreground or zodiacal emission within the field-of-view. Therefore, an instrument design that restricts the spectral bandpass viewed by the detector must be employed. One method of achieving background limited, high resolution spectroscopy is to combine a high resolution component such as a Fabry–Pérot interferometer (FPI) with a lower resolution, post-dispersing system, such as a grating spectrometer, the latter serving to restrict the spectral bandpass. The resonant wavelength of an FPI is most often tuned by changing the spacing or medium between the parallel reflecting plates of the etalon. In this paper, we present a novel design for an FPI in which the wavelength is tuned by scanning the angle of incidence on a high refractive index etalon. This concept simplifies the cryomechanical design, actuation, and metrology. The first results from the realized instrument are presented and compared with theory. The effects on the spectral response as a function of the incident angle have been simulated and shown to agree well with the observation

Clinical Management of Hyperkalemia

© 2020 Mayo Foundation for Medical Education and Research Hyperkalemia is an electrolyte abnormality with potentially life-threatening consequences. Despite various guidelines, no universally accepted consensus exists on best practices for hyperkalemia monitoring, with variations in precise potassium (K+) concentration thresholds or for the management of acute or chronic hyperkalemia. Based on the available evidence, this review identifies several critical issues and unmet needs with regard to the management of hyperkalemia. Real-world studies are needed for a better understanding of the prevalence of hyperkalemia outside the clinical trial setting. There is a need to improve effective management of hyperkalemia, including classification and K+ monitoring, when to reinitiate previously discontinued renin-angiotensin-aldosterone system inhibitor (RAASi) therapy, and when to use oral K+-binding agents. Monitoring serum K+ should be individualized; however, increased frequency of monitoring should be considered for patients with chronic kidney disease, diabetes, heart failure, or a history of hyperkalemia and for those receiving RAASi therapy. Recent clinical studies suggest that the newer K+ binders (patiromer sorbitex calcium and sodium zirconium cyclosilicate) may facilitate optimization of RAASi therapy. Enhancing the knowledge of primary care physicians and internists with respect to the safety profiles of these newer K+ binders may increase confidence in managing patients with hyperkalemia. Lastly, the availability of newer K+-binding agents requires further study to establish whether stringent dietary K+ restrictions are needed in patients receiving K+-binder therapy. Individualized monitoring of serum K+ among patients with an increased risk of hyperkalemia and the use of newer K+-binding agents may allow for optimization of RAASi therapy and more effective management of hyperkalemia

Institutional maintenance work and power preservation in business exchanges: Insights from industrial supplier workshops

This paper aims to offer new theoretical and empirical insights into power dynamics in an industrial supplier workshop setting. Theoretically, it advances an institutional perspective on supplier workshops as an important venue in managing, preserving and instituting industrial market power. Based on a detailed ethnographic analysis of an industrial workshop setting, this article investigates the institutional maintenance work of Retail Co. in preserving the power dynamics of market dominance in business exchanges and market structures. Our findings revealed three previously unreported insights into the subtle, but nonetheless pervasive power from institutional maintenance work in an industrial workshop setting. First, the institutional workshop work comprised a cultural performance; constituting socialization practice through a performance game, the power of numbers in field comprehension and an award ceremony. Second, the institutional workshop work mobilized projective agency, stipulating, directing and appealing for the instituting of distinct market rules and collective identities. Finally, the institutional workshop work increases supplier docility and utility via the regulative technologies-of-the-self to enhance business planning, operations and market decision-making practice, without necessarily being seen to be disciplinarian. (C) 2015 Elsevier Inc. All rights reserved

The cooling of atomic and molecular gas in DR21

We present an overview of a high-mass star formation region through the major (sub-)mm, and far-infrared cooling lines to gain insight into the physical conditions and the energy budget of the molecular cloud. We used the KOSMA 3m telescope to map the core ($10'\times 14'$) of the Galactic star forming region DR 21/DR 21 (OH) in the Cygnus X region in the two fine structure lines of atomic carbon CI and four mid-$J$ transitions of CO and $^{13}$CO, and CS J=7\TO6. These observations have been combined with FCRAO J=1\TO0 observations of $^{13}$CO and C$^{18}$O. Five positions, including DR21, DR21 (OH), and DR21 FIR1, were observed with the ISO/LWS grating spectrometer in the \OI 63 and 145 $\mu$m lines, the \CII 158 $\mu$m line, and four high-$J$ CO lines. We discuss the intensities and line ratios at these positions and apply Local Thermal Equilibrium (LTE) and non-LTE analysis methods in order to derive physical parameters such as masses, densities and temperatures. The CO line emission has been modeled up to J=20. From non-LTE modeling of the low- to high-$J$ CO lines we identify two gas components, a cold one at temperatures of T_\RM{kin}\sim 30-40 K, and one with T_\RM{kin}\sim 80-150 K at a local clump density of about n(H$_2$)$\sim 10^4-10^6$ cm$^{-3}$. While the cold quiescent component is massive containing typically more than 94 % of the mass, the warm, dense, and turbulent gas is dominated by mid- and high-$J$ CO line emission and its large line widths. The medium must be clumpy with a volume-filling of a few percent. The CO lines are found to be important for the cooling of the cold molecular gas, e.g. at DR21 (OH). Near the outflow of the UV-heated source DR21, the gas cooling is dominated by line emission of atomic oxygen and of CO