Surveying the upper Ocean with the Ocean Surveyor - a new Phased Array Doppler Current Profiler

A new shipboard current profiler, a 75-kHz ocean surveyor, was operationally used during two research cruises in the tropical Atlantic and the subpolar North Atlantic, respectively. Here, a report is presented on the first experience with this instrument in two very different current regimes, in the Tropics with large vertical shears, and in the subpolar regime with mainly barotropic flow. The ocean surveyor continuously measured currents in the upper ocean from near the surface to about 500–700-m depth. The measurement range showed a dependence on the regional and temporal variations of scattering particles and on the intensity of swell and wind waves. Statistical comparisons are performed with on-station lowered acoustic Doppler current profiler (LADCP) profiles and underway measurements by classic shipboard acoustic Doppler current profiler (ADCP) measurements. Accuracy estimates for hourly averaged ocean surveyor currents result in errors of about 1 cm s–1 for on-station data and of 2–4 cm s–1 for underway measurements, depending on the regional abundance of scatterers and on the weather conditions encountered

Nitrate and nitrite variability at the seafloor of an oxygen minimum zone revealed by a novel microfluidic in-situ chemical sensor

Microfluidics, or lab-on-a-chip (LOC) is a promising technology that allows the development of miniaturized chemical sensors. In contrast to the surging interest in biomedical sciences, the utilization of LOC sensors in aquatic sciences is still in infancy but a wider use of such sensors could mitigate the undersampling problem of ocean biogeochemical processes. Here we describe the first underwater test of a novel LOC sensor to obtain in situ calibrated time-series (up to 40 h) of nitrate+nitrite (ΣNOx) and nitrite on the seafloor of the Mauritanian oxygen minimum zone, offshore Western Africa. Initial tests showed that the sensor successfully reproduced water column (160 m) nutrient profiles. Lander deployments at 50, 100 and 170 m depth indicated that the biogeochemical variability was high over the Mauritanian shelf: The 50 m site had the lowest ΣNOx concentration, with 15.2 to 23.4 μM (median=18.3 μM); while at the 100 site ΣNOx varied between 21.0 and 30.1 μM over 40 hours (median = 25.1μM). The 170 m site had the highest median ΣNOx level (25.8 μM) with less variability (22.8 to 27.7 μM). At the 50 m site, nitrite concentration decreased fivefold from 1 to 0.2 μM in just 30 hours accompanied by decreasing oxygen and increasing nitrate concentrations. Taken together with the time series of oxygen, temperature, pressure and current velocities, we propose that the episodic intrusion of deeper waters via cross-shelf transport leads to intrusion of nitrate-rich, but oxygen-poor waters to shallower locations, with consequences for benthic nitrogen cycling. This first validation of an LOC sensor at elevated water depths revealed that when deployed for longer periods and as a part of a sensor network, LOC technology has the potential to contribute to the understanding of the benthic biogeochemical dynamics

Drivers of plant diversity in Bulgarian dry grasslands vary across spatial scales and functional-taxonomic groups

Questions: Studying dry grasslands in a previously unexplored region, we asked: (a) which environmental factors drive the diversity patterns in vegetation; (b) are taxonomic groups (vascular plants, bryophytes, lichens) and functional vascular plant groups differently affected; and (c) how is fine-grain beta diversity affected by environmental drivers? Location: Northwestern and Central Bulgaria. Methods: We sampled environmental data and vascular plant, terricolous bryophyte and lichen species in 97 10-m2 plots and 15 nested-plot series with seven grain sizes (0.0001–100 m2) of ten grassland sites within the two regions. We used species richness as measure of alpha-diversity and the z-value of the power-law species–area relationship as measure of beta-diversity. We analysed effects of landscape, topographic, soil and land-use variables on the species richness of the different taxonomic and functional groups. We applied generalised linear models (GLMs) or, in the presence of spatial autocorrelation, generalised linear mixed-effect models (GLMMs) in a multi-model inference framework. Results: The main factors affecting total and vascular plant species richness in 10-m2 plots were soil pH (unimodal) and inclination (negative). Species richness of bryophytes was positively affected by rock cover, sand proportion and negatively by inclination. Inclination and litter cover were also negative predictors of lichen species richness. Elevation negatively affected phanerophyte and therophyte richness, but positively that of cryptophytes. A major part of unexplained variance in species richness was associated with the grassland site. The z-values for total richness showed a positive relationship with elevation and inclination. Conclusions: Environmental factors shaping richness patterns strongly differed among taxonomic groups, functional vascular plant groups and spatial scales. The disparities between our and previous findings suggest that many drivers of biodiversity cannot be generalised but rather depend on the regional context. The large unexplained variance at the site level calls for considering more site-related factors such as land-use history

The Eurasian Dry Grassland Group (EDGG) in 2016-2017

This report summarizes the activities and achievements of the Eurasian Dry Grassland Group (EDGG) from mid-2016 through to the end of 2017. During this period, the 13th Eurasian Grassland Conference took place in Sighişoara, Romania, and the 14th conference was held in Riga, Latvia. The 10th EDGG Field Workshop on Biodiversity patterns across a precipitation gradient in the Central Apennine mountains was conducted in the Central Apennines, Italy, this time in addition to multi-scale sampling of vascular plants, bryophytes and lichens, also including one animal group (leaf hoppers). Apart from the quarterly issues of its own electronic journal (Bulletin of the Eurasian Dry Grassland Group), EDGG also finalised five grassland-related Special Features/Issues during the past 1.5 years in the following international journals: Applied Vegetation Science, Biodiversity and Conservation, Phytocoenologia, Tuexenia and Hacquetia. Beyond that, EDGG facilitated various national and supra-national vegetationplot databases of grasslands and established its own specialised database for standardised multi-scale plot data of Palaearctic grasslands (GrassPlot). © by Stephen Venn 2018.Peer reviewe

Accelerated lifetime testing and failure analysis of quartz based GaAs planar Schottky diodes

Accelerated lifetime tests have been performed on integrated planar GaAs Schottky diodes that were bonded to quartz substrates upside-down with a heat-cured epoxy. Results at 175°C, 200°C, and 240°C were analyzed using the Arrhenius-lognormal model. These tests predict a room temperature MTTF of 3x10^8 hours, a value that is comparable to conventional high-frequency planar Schottky diodes. This result demonstrates that the use of an appropriate epoxy to obtain GaAs devices on quartz substrates does not significantly reduce the lifetime of the devices

Resumption of elective orthopaedic surgery in the us epicenter of covid-19

© 2020 Krauss et al. On March 1, 2020, New York State confirmed its first case of COVID-19. This state has had the largest initial mortality in the United States with more than 479,000 confirmed cases and over 25,000 deaths as of October 10, 2020. All elective surgeries in New York State were suspended on March 23, 2020, due to the national state of emergency. Syosset Hospital is a 75-bed community hospital dedicated primarily to elective surgery. During the COVID-19 surge, the hospital was converted to provide needed beds for the treatment of COVID-19 illness. In anticipation of the resumption of urgent elective procedures, this hospital became one of the two designated sites within the Northwell Health system to be “non-COVID.” Once the hospital was emptied of all inpatients, a complete and thorough cleaning and disinfection was performed on the entire building. All equipment was thoroughly decontaminated following Centers for Disease Control and Prevention (CDC) guidelines. In anticipation of the resumption of elective surgery, each surgeon evaluated their cancelled case list to determine patient priority, based on a scale of 1 (elective, non-urgent), 2 (semi-urgent), 3 (urgent), to 4 (highly urgent). Site-specific disaster credentialing was expedited so that emergent surgeries could be performed by surgeons located at other Northwell sites. To ensure a structured and informative onboarding process, each visiting surgeon received a “welcome” email which requested pertinent information to facilitate the surgical process. Presurgical, surgical, and postoperative protocols were revised based on federal and local guidance and regulations. Resumption of elective surgery post COVID-19 placed the hospital into uncharted territory

The Eurasian Dry Grassland Group (EDGG) in 2015-2016

Peer reviewe