Seagrass Distribution in the Pensacola Bay System, Northwest Florida

Aerial surveys of seagrass coverage in the Pensacola Bay system (PBS) have been conducted during 1960, 1980, 1992 and 2003. This report summarizes the results for the 2003 survey and compares the results to those previously reported for other surveys. The estimated coverage of seagrass for the PBS during 2003 was 1,654 ha. Continuous and patchy coverages ranged from 0 to 684 ha and 11 to 543 ha, respectively, for five PBS subsystems. In 2003, the majority of seagrass coverage occurred in Santa Rosa Sound (76%). Declines in total coverage occurred for East Bay (93%) and Escambia Bay (75%) whereas increases were observed for Pensacola Bay (32%) and Santa Rosa Sound (8%). The approximate 9% decline (about 160 ha or 395 a) in total coverage since 1992 represents an estimated 7 to 8 million dollar loss in ecological services. The changes in coverage are likely due to naturally occurring and anthropogenic factors but it is not possible to differentiate the relative contributions of these factors alone and in combination on seagrass distribution. The ability of seagrasses to exist long-term in Florida’s fourth largest estuarine system is uncertain due to the adverse effects of rapid urbanization in the watershed. Active resource management which includes more frequent in-situ monitoring and aerial assessment and the availability of relevant water and sediment quality criteria protective of submerged aquatic vegetation are needed to prevent future declines

Combining microsatellites, growth, and adaptive traits for managing in situ genetic resources of Eucalyptus urophylla

International audienceGenetic diversity and structure of 17 populations representative of the natural range of Eucalyptus urophylla S.T. Blake in Indonesia were analysed with 10 microsatellite markers. Two provenance and progeny trials, using the same populations, were established in the Republic of the Congo and analysed for growth and survival at 37months. Observed microsatellite heterozygosity (Ho) was moderate to high within populations (Ho = 0.51-0.72). The index of fixation (FIS) was significantly different from zero for all populations (FIS = 0.13-0.31) and possibly resulted from a Wahlund effect. The differentiation parameter was low (FST = 0.04) and not significantly different from zero, which can be explained by effective gene flow via pollen. The genetic variances within and among provenances for survival and growth traits were significantly different from zero, representing 13%-23% and 14%-50% of the total variation, respectively. The differentiation between populations based on quantitative traits was marked (QST = 0.07-0.33). A negative relationship between altitude of the seed source and its performance in the Congo was observed (R2 = 0.59-0.67) and could be explained by the effect of natural selection along the altitudinal gradient. This marked differentiation for quantitative traits despite high apparent gene flow results in a clinal variation, which suggests the use of altitude of seed source as an important principle for in situ or ex situ management of E. urophylla genetic resources. À l'aide de 10 marqueurs microsatellites, les auteurs ont analysé la diversité et la structure génétiques de 17 populations représentatives de l'aire naturelle d'Eucalyptus urophylla S.T. Blake en Indonésie. La croissance et la survie après 37 mois ont été analysées dans deux essais établis en République du Congo et contenant les mêmes provenances et descendances. L'hétérozygotie observée (Ho) chez les marqueurs microsatellites variait de modérée à élevée au sein des populations (Ho = 0,51-0,72). L'indice FIS était significativement différent de zéro pour toutes les populations (FIS = 0,13-0,31) et était possiblement le résultat d'un effet de Wahlund. La différenciation de population était faible (FST = 0,04) et n'était pas significativement différente de zéro, ce qui peut s'expliquer par un flux génique efficace attribuable au pollen. Les variances génétiques au sein et parmi les provenances pour les caractères de survie et de croissance étaient significativement différentes de zéro, représentant respectivement 13% à 23% et 14% à 50% de la variation totale. La différenciation de population estimée à partir des caractères quantitatifs était élevée, avec une valeur de QST = 0,07-0,33. Une relation négative entre l'altitude des sources de semences et leur performance au Congo a été remarquée (R2 = 0,59-0,67). Cette relation pourrait s'expliquer par l'effet de la sélection naturelle le long du gradient altitudinal. Cette différenciation marquée chez les caractères quantitatifs, en dépit d'un flux génique apparent élevé, se manifeste par un patron de variation clinale, ce qui indique que l'altitude des sources de semences est un critère important qui devrait être utilisé pour la gestion in situ et ex situ des ressources génétiques d'E. urophyll

Algebraic Torsion in Contact Manifolds

We extract a nonnegative integer-valued invariant, which we call the "order of algebraic torsion", from the Symplectic Field Theory of a closed contact manifold, and show that its finiteness gives obstructions to the existence of symplectic fillings and exact symplectic cobordisms. A contact manifold has algebraic torsion of order zero if and only if it is algebraically overtwisted (i.e. has trivial contact homology), and any contact 3-manifold with positive Giroux torsion has algebraic torsion of order one (though the converse is not true). We also construct examples for each nonnegative k of contact 3-manifolds that have algebraic torsion of order k but not k - 1, and derive consequences for contact surgeries on such manifolds. The appendix by Michael Hutchings gives an alternative proof of our cobordism obstructions in dimension three using a refinement of the contact invariant in Embedded Contact Homology.Comment: 53 pages, 4 figures, with an appendix by Michael Hutchings; v.3 is a final update to agree with the published paper, and also corrects a minor error that appeared in the published version of the appendi

Creating traveling waves from standing waves from the gyrotropic paramagnetic properties of Fe3+^{3+} ions in a high-Q whispering gallery mode sapphire resonator

We report observations of the gyrotropic change in magnetic susceptibility of the Fe$^{3+}$ electron paramagnetic resonance at 12.037GHz (between spin states $|1/2>$ and $|3/2>$) in sapphire with respect to applied magnetic field. Measurements were made by observing the response of the high-Q Whispering Gallery doublet (WGH$_{\pm17,0,0}$) in a Hemex sapphire resonator cooled to 5 K. The doublets initially existed as standing waves at zero field and were transformed to traveling waves due to the gyrotropic response.Comment: Accepted for publication in Phys. Rev.

Inelastic scattering of transversely structured free electrons from nanophotonic targets: Theory and computation

Recent advancements in abilities to create and manipulate the electron's transverse wave function within the transmission electron microscope (TEM) and scanning TEM (STEM) have enabled vectorially-resolved electron energy loss (EEL) and gain (EEG) measurements of nanoscale and quantum material responses using pre- and post-selected free electron states. This newfound capability is prompting renewed theoretical interest in quantum mechanical treatments of inelastic electron scattering observables and the information they contain. Here, we present a quantum mechanical treatment of the inelastic scattering of free electrons between pre- and post-selected transverse states with fully-retarded electron-sample interactions for both spontaneous EEL and continuous-wave laser-stimulated EEG measurements. General expressions for the state-resolved energy loss and gain rates are recast in forms amenable to numerical calculation using the method of coupled dipoles. We numerically implement our theory within the $e$-DDA code, and use it to investigate specific examples that highlight its versatility regarding the number, size, geometry, and material composition of the target specimen, as well as its ability to describe matter-wave diffraction from finite nanoscopic targets

Experimentally heat‐induced transposition increases drought tolerance in Arabidopsis thaliana

Eukaryotic genomes contain a vast diversity of transposable elements (TEs). Formerly often described as selfish and parasitic DNA sequences, TEs are now recognized as a source of genetic diversity and powerful drivers of evolution. Yet, because their mobility is tightly controlled by the host, studies experimentally assessing how fast TEs may mediate the emergence of adaptive traits are scare. We exposed Arabidopsis thaliana high-copy TE lines (hcLines) with up to ~8 fold increased copy numbers of the heat-responsive ONSEN TE to drought as a straightforward and ecologically highly relevant selection pressure. We provide evidence for increased drought tolerance in five out of the 23 tested hcLines and further pinpoint one of the causative mutations to an exonic insertion of ONSEN in the ribose-5-phosphate-isomerase 2 gene. The resulting loss-of-function mutation caused a decreased rate of photosynthesis, plant size and water consumption. Overall, we show that the heat-induced transposition of a low-copy TE increases phenotypic diversity and leads to the emergence of drought-tolerant individuals in Arabidopsis thaliana. This is one of the rare empirical examples substantiating the adaptive potential of mobilized stress-responsive TEs in eukaryotes. Our work demonstrates the potential of TE-mediated loss-of-function mutations in stress adaptation

Single-pulse Laue diffraction, stroboscopic data collection and femtosecond flash photolysis on macromolecules

We review the time structure of synchrotron radiation and its use for fast time-resolved diffraction experiments in macromolecular photo-cycles using flash photolysis to initiate the reaction. The source parameters and optics for ID09 at ESRF are presented together with the phase-locked chopper and femtosecond laser. The chopper can set up a 900 Hz pulse train of 100 ps pulses from the hybrid bunch-mode and, in conjunction with a femtosecond laser, it can be used for stroboscopic data collection with both monochromatic and polychromatic beams. Single-pulse Laue data from Cutinase, a 22 kD lipolic enzyme, are presented which show that the quality of single-pulse Laue patterns is sufficient to refine the excited state(s) in a reaction pathway from a known ground state. The flash photolysis technique is discussed and an example is given for heme proteins. The radiation damage from a laser pulse in the femto and picosecond range can be reduced by triggering at a wavelength where the interaction is strong. We propose the use of microcrystals between 25–50 μm for efficient photolysis with femto and picosecond pulses. The performance of circular storage rings is compared with the predicted performance of an X-ray free electron laser (XFEL). The combination of micro beams, a gain of 105105 photons per pulse and an ultrashort pulse length of 100 fs is likely to improve pulsed diffraction data very substantially. It may be used to image coherent nuclear motion at atomic resolution in ultrafast uni-molecular reactions. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87418/2/267_1.pd

Supplementary data for: "The demographic history of the wild crop relative Brachypodium distachyon is shaped by distinct past and present ecological niches"

Supplementary data to https://doi.org/10.1101/2023.06.01.54328