scholarly journals After Hurricanes Irma and Matthew: Living Shorelines Stabilize Sediments

2019 ◽  
Vol 16 (2) ◽  
pp. 63-72
Author(s):  
Taryn Chaya ◽  
Jessica Veenstra ◽  
Melissa Southwell
Keyword(s):  
Sediment Cores ◽  
High Energy ◽  
Storm Events ◽  
Oyster Reefs ◽  
Living Shorelines ◽  
Before And After ◽  
National Estuarine Research Reserve ◽  
Sediment Profiles ◽  
Oyster Restoration ◽  
Sediment Data

Constructed intertidal oyster reefs, an example of a “living shoreline”, can protect against erosion and loss of habitat, but can they prevent erosion during high-energy storm events such as hurricanes? Oyster reefs were constructed in 2012 within the Guana Tolomato Matanzas National Estuarine Research Reserve in Northeast Florida to stabilize the shoreline sediment and prevent erosion of an archeological site. Sediment cores were collected behind constructed oyster reefs before and after hurricanes Matthew (2016) and Irma (2017) to study changes in sediment particle size due to these high-energy storms. Pre-hurricane data were collected in 2016 from three different constructed reefs, as well as three control sites where no reef was present. Pre-hurricane sediment profiles behind the constructed reefs consisted of finer sediments, ~36% silt and clay, in the surface ~10-12 cm, with decreasing silt and clay and increasing sand content as depth increased. This was different than the sediment from the control sites with ~4% silt and clay in all depths sampled. Like the sediment profiles before the high energy storms, the post-hurricane sediment data showed a clear layer of finer sediment ~10-12 cm over coarser sediment. Although they were high-energy storms, the storms did not appear to significantly affect the sediment behind the constructed oyster reefs. Sediment profiles remained consistent after these storms but may not remain undisturbed during the next storm without some intervention because the oyster reefs have been degrading. KEYWORDS: Oyster Restoration; Living Shorelines; Hurricanes; Coastal Erosion; Sedimentation; Salt Marsh

An Assessment of Environmental Changes in Three Lakes from King's County (Nova Scotia, Canada) Using Diatom-Based Paleolimnological Techniques

2008 ◽  
Vol 43 (2-3) ◽  
pp. 85-98 ◽  
Author(s):  
Joshua R. Thienpont ◽  
Brian K. Ginn ◽  
Brian F. Cumming ◽  
John P. Smol
Keyword(s):  
Nova Scotia ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Lake Management ◽  
River System ◽  
210Pb Dating ◽  
Hydroelectric Power ◽  
Diatom Assemblages ◽  
Shoreline Development ◽  
Before And After

Abstract Paleolimnological approaches using sedimentary diatom assemblages were used to assess water quality changes over the last approximately 200 years in three lakes from King's County, Nova Scotia. In particular, the role of recent shoreline development in accelerating eutrophication in these systems was assessed. Sediment cores collected from each lake were analyzed for their diatom assemblages at approximately 5-year intervals, as determined by 210Pb dating. Analyses showed that each system has changed, but tracked different ecosystem changes. Tupper and George lakes recorded shifts, which are likely primarily related to climatic warming, with diatom assemblages changing from a preindustrial dominance by Aulacoseira spp. to present-day dominance by Cyclotella stelligera. In addition to the recent climatic-related changes, further diatom changes in the Tupper Lake core between approximately 1820 and 1970 were coincident with watershed disturbances (farming, forestry, and construction of hydroelectric power infrastructure). Black River Lake has recorded an increase in diatom-inferred total phosphorus since about 1950, likely due to impoundment of the Black River system for hydroelectric generation and subsequent changes in land runoff. Before-and-after (i.e., top-bottom) sediment analyses of six other lakes from King's County provided further evidence that the region is being influenced by climatic change (decreases in Aulacoseira spp., increases in planktonic diatom taxa), as well as showing other environmental stressors (e.g., acidification). However, we recorded no marked increase in diatom-inferred nutrient levels coincident with shoreline cottage development in any of the nine study lakes. Paleolimnological studies such as these allow lake managers to place the current limnological conditions into a long-term context, and thereby provide important background data for effective lake management.

Epinephrine inhibits insulin-mediated glycogenesis but enhances glycolysis in human skeletal muscle

1991 ◽  
Vol 260 (3) ◽  
pp. E430-E435 ◽  
Author(s):  
I. Raz ◽  
A. Katz ◽  
M. K. Spencer
Keyword(s):  
Glycogen Synthase ◽  
Glucose Production ◽  
High Energy ◽  
Endogenous Glucose Production ◽  
Fat Free Mass ◽  
Glucose Disposal ◽  
High Energy Phosphates ◽  
Before And After ◽  
Glucose Tolerant ◽  
Femoris Muscle

The effect of epinephrine (E) infusion on insulin-mediated glucose metabolism in humans has been studied. Eight glucose-tolerant men were studied on two separate occasions: 1) during 120 min of euglycemic hyperinsulinemia (UH, approximately 5 mM; 40 mU.m-2.min-1); and 2) during UH while E was infused (UHE, 0.05 microgram.kg-1.min-1). Biopsies were taken from the quadriceps femoris muscle before and after each clamp. Glucose disposal, correcting for endogenous glucose production, was 36 +/- 3 and 18 +/- 2 (SE) mumol.kg fat-free mass (FFM)-1.min-1 during the last 40 min of UH and UHE, respectively (P less than 0.001). Nonoxidative glucose disposal (presumably glycogenesis) averaged 23.0 +/- 3.0 and 4.0 +/- 1.1 (P less than 0.001), whereas carbohydrate oxidation (which is proportional to glycolysis) averaged 13.1 +/- 1.4 and 15.3 +/- 1.1 mumol.kg FFM-1.min-1 (P less than 0.05) during UH and UHE, respectively. UHE resulted in significantly higher contents of UDP-glucose, hexose monophosphates, postphosphofructokinase intermediates, and glucose 1,6-bisphosphate (G-1,6-P2) in muscle (P less than 0.05-0.001), but there were no significant differences in high-energy phosphates or fructose 2,6-bisphosphate (F-2,6-P2) between treatments. Fractional activities of phosphorylase increased (P less than 0.01), and glycogen synthase decreased (P less than 0.001) during UHE. It is concluded that E inhibits insulin-mediated glycogenesis because of an inactivation of glycogen synthase and an activation of glycogenolysis. E also appears to inhibit insulin-mediated glucose utilization, at least partly, because of an increase in G-6-phosphate (which inhibits hexokinase) and enhances glycolysis by G-1,6-P2-, fructose 6-phosphate-, and F-1,6-P2-mediated activation of PFK.

Fatigue and phosphocreatine depletion during carbon dioxide-induced acidosis in rat muscle

1983 ◽  
Vol 245 (1) ◽  
pp. C15-C20 ◽  
Author(s):  
K. Sahlin ◽  
L. Edstrom ◽  
H. Sjoholm
Keyword(s):  
High Energy ◽  
Initial Value ◽  
High Co2 ◽  
Fourfold Increase ◽  
Control Value ◽  
Before And After ◽  
Phosphate Depletion ◽  
Creatine Kinase Equilibrium ◽  
Lactate And Pyruvate ◽  
Tetanic Tension

Isolated extensor digitorum longus muscles from rat were exposed to atmospheres of 30% CO2 (high-CO2 muscles) or 6.5% CO2 (control muscles) in O2 for 95 min. Muscle contraction characteristics were studied before and after the incubation. Tetanic tension decreased in high-CO2 muscles to 55% of initial value but remained unchanged in control muscles. Relaxation time was prolonged in high-CO2 muscles but not in control muscles. Intracellular pH was 6.67 +/- 0.04 (SD) in high-CO2 muscles and 7.01 +/- 0.04 in control muscles. CO2-induced acidosis had a marked influence on the intermediary energy metabolism as shown by a fourfold increase of glucose 6-phosphate, a 14% increase of ADP, and a decrease of phosphocreatine to 44% of the control value. Lactate and pyruvate contents were unchanged. The observed metabolic changes can be explained by an effect of H+ on the activity of phosphofructokinase and on the creatine kinase equilibrium. It can be concluded that H+ concentration causes muscular fatigue. It is, however, uncertain whether this is an effect of increased H+ per se or by high-energy phosphate depletion induced by acidosis.

Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy

2013 ◽  
Vol 28 (2) ◽  
pp. 68-71 ◽  
Author(s):  
Thomas N. Blanton ◽  
Debasis Majumdar
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Ray Diffraction ◽  
Carbon Phase ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

scholarly journals The effects of the big storm events in the first half of 2015 on the radiation belts observed by EPT/PROBA-V

2016 ◽  
Vol 34 (1) ◽  
pp. 75-84 ◽  
Author(s):  
V. Pierrard ◽  
G. Lopez Rosson
Keyword(s):  
Charged Particle ◽  
High Resolution ◽  
Geomagnetic Storm ◽  
Energetic Particle ◽  
High Energy ◽  
Radiation Belts ◽  
Radiation Environment ◽  
Storm Event ◽  
Storm Events ◽  
Particle Radiation

Abstract. With the energetic particle telescope (EPT) performing with direct electron and proton discrimination on board the ESA satellite PROBA-V, we analyze the high-resolution measurements of the charged particle radiation environment at an altitude of 820 km for the year 2015. On 17 March 2015, a big geomagnetic storm event injected unusual fluxes up to low radial distances in the radiation belts. EPT electron measurements show a deep dropout at L > 4 starting during the main phase of the storm, associated to the penetration of high energy fluxes at L < 2 completely filling the slot region. After 10 days, the formation of a new slot around L = 2.8 for electrons of 500–600 keV separates the outer belt from the belt extending at other longitudes than the South Atlantic Anomaly. Two other major events appeared in January and June 2015, again with injections of electrons in the inner belt, contrary to what was observed in 2013 and 2014. These observations open many perspectives to better understand the source and loss mechanisms, and particularly concerning the formation of three belts.

scholarly journals Detection of very-high-energy γ-ray emission from the colliding wind binary η Car with H.E.S.S.

2020 ◽  
Vol 635 ◽  
pp. A167 ◽  
Author(s):  
◽  
H. Abdalla ◽  
R. Adam ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Binary Systems ◽  
High Energy ◽  
Emission Region ◽  
Reconstructed Signal ◽  
Additional Noise ◽  
Before And After ◽  
Orbital Phase ◽  
Very High Energy ◽  
Stereoscopic System ◽  
Very High

Aims. Colliding wind binary systems have long been suspected to be high-energy (HE; 100 MeV < E < 100 GeV) γ-ray emitters. η Car is the most prominent member of this object class and is confirmed to emit phase-locked HE γ rays from hundreds of MeV to ~100 GeV energies. This work aims to search for and characterise the very-high-energy (VHE; E >100 GeV) γ-ray emission from η Car around the last periastron passage in 2014 with the ground-based High Energy Stereoscopic System (H.E.S.S.). Methods. The region around η Car was observed with H.E.S.S. between orbital phase p = 0.78−1.10, with a closer sampling at p ≈ 0.95 and p ≈ 1.10 (assuming a period of 2023 days). Optimised hardware settings as well as adjustments to the data reduction, reconstruction, and signal selection were needed to suppress and take into account the strong, extended, and inhomogeneous night sky background (NSB) in the η Car field of view. Tailored run-wise Monte-Carlo simulations (RWS) were required to accurately treat the additional noise from NSB photons in the instrument response functions. Results. H.E.S.S. detected VHE γ-ray emission from the direction of η Car shortly before and after the minimum in the X-ray light-curve close to periastron. Using the point spread function provided by RWS, the reconstructed signal is point-like and the spectrum is best described by a power law. The overall flux and spectral index in VHE γ rays agree within statistical and systematic errors before and after periastron. The γ-ray spectrum extends up to at least ~400 GeV. This implies a maximum magnetic field in a leptonic scenario in the emission region of 0.5 Gauss. No indication for phase-locked flux variations is detected in the H.E.S.S. data.

scholarly journals Numerical Study of the Dynamic Compaction Process considering the Phenomenon of Particle Breakage

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xi Li ◽  
Jing Li ◽  
Xinyan Ma ◽  
Jidong Teng ◽  
Sheng Zhang
Keyword(s):  
Numerical Study ◽  
High Energy ◽  
Particle Breakage ◽  
Dynamic Compaction ◽  
Coarse Grained ◽  
Impact Stress ◽  
Logarithmic Curve ◽  
Before And After ◽  
Soil Foundation ◽  
Overlapping Method

Dynamic compaction (DC) is commonly used to strengthen the coarse grained soil foundation, where particle breakage of coarse soils is unavoidable under high-energy impacts. In this paper, a novel method of modeling DC progress was developed, which can realize particle breakage by impact stress. A particle failure criterion of critical stress is first employed. The “population balance” between particles before and after crushing is guaranteed by the overlapping method. The performance of the DC model is successfully validated against literature data. A series of DC tests were then carried out. The effect of particle breakage on key parameters of DC including crater depth and impact stress was discussed. Besides, it is observed that the relationship between breakage amount and tamping times can be expressed by a logarithmic curve. The present method will contribute to a better understanding of DC and benefit further research on the macro-micro mechanism of DC.

Preparation of Ge (100) Substrates for High-Quality Epitaxial Growth of Group IV Materials

2003 ◽  
Vol 794 ◽  
Author(s):  
Mark Nowakowski ◽  
Jordana Bandaru ◽  
L.D. Bell ◽  
Shouleh Nikzad
Keyword(s):  
Epitaxial Growth ◽  
Chemical Treatment ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
Ozone Treatment ◽  
High Quality ◽  
Surface Evolution ◽  
Chemical Treatments ◽  
Before And After ◽  
Uv Ozone

ABSTRACTWe compare various wet chemical treatments, in preparing high-quality Ge (100) surfaces suitable for molecular beam epitaxy (MBE). Various surface treatments are explored such as UV-ozone treatment followed by exposure to chemical solutions such as de-ionized (DI) water, hydrofluoric acid (HF), or hydrochloric acid (HCl). Chemical treatments to remove the oxide are performed in a nitrogen environment to prevent further formation of surface oxide prior to surface analysis. Following chemical treatments, in situ reflection high-energy electron diffraction (RHEED) analysis is performed to observe the surface evolution as a function of temperature. In a separate chamber, we analyze each sample, before and after chemical treatment by x-ray photoelectron spectroscopy (XPS) to directly determine the oxide desorption following each chemical treatment. Our results of this comparative study, the effectiveness of each chemical treatment, and the stability of the passivated surface suggest that UV ozone cleaning, followed by 10% HCl is the best choice for removing most of the oxide. Furthermore, we present evidence of high quality epitaxial growth of SnxGe1−x on wafers prepared by our method.

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