A5084626015- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Freshwater macroinvertebrate diversity and ecology
- Fish Ecology and Management Studies
- Antenna Design and Analysis
- Microwave Engineering and Waveguides
- Advanced Antenna and Metasurface Technologies
- Aquatic Ecosystems and Phytoplankton Dynamics
- Wastewater Treatment and Nitrogen Removal
- Neuroscience and Neural Engineering
- Wireless Body Area Networks
- Urban Stormwater Management Solutions
- Energy Harvesting in Wireless Networks
- Wireless Power Transfer Systems
- Photoreceptor and optogenetics research
- Coastal wetland ecosystem dynamics
- Heavy metals in environment
- Diatoms and Algae Research
- Water Quality and Resources Studies
- Advanced Chemical Sensor Technologies
- Aquatic Invertebrate Ecology and Behavior
- Groundwater and Isotope Geochemistry
- Advanced MRI Techniques and Applications
- Vagus Nerve Stimulation Research
- Environmental Toxicology and Ecotoxicology
Draper Laboratory
2017-2019
Canisius College
2013-2018
University of Canterbury
2010-2017
Michigan State University
2007-2016
University of South Florida
2013-2015
Kansas State University
2006-2010
University of Kansas
2009
Newcastle University
2009
National Microelectronics Applications Centre (Ireland)
2002
Nitrous oxide (N(2)O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading river networks potentially important source of N(2)O via microbial denitrification converts N dinitrogen (N(2)). The fraction denitrified escapes as rather than N(2) (i.e., the yield) an determinant how much produced by networks, but little known about yield in flowing waters. Here, we present results whole-stream (15)N-tracer additions...
Summary 1. Rates of whole‐system metabolism (production and respiration) are fundamental indicators ecosystem structure function. Although first‐order, proximal controls well understood, assessments the interactions between distal controls, such as land use geographic region, lacking. Thus, influence on stream across regions is unknown. Further, there limited understanding how may alter variability in regions. 2. Stream was measured nine streams each eight ( n = 72) United States Puerto...
We measured uptake length of 15 NO 3 − in 72 streams eight regions across the United States and Puerto Rico to develop quantitative predictive models on controls length. As part Lotic Intersite Nitrogen eXperiment II project, we chose nine each region corresponding natural (reference), suburban‐urban, agricultural land uses. Study spanned a range human use maximize variation concentration, geomorphology, metabolism. tested causal model predicting using structural equation modeling. The...
We measured denitrification rates using a field 15 NO 3 − tracer‐addition approach in large, cross‐site study of nitrate uptake reference, agricultural, and suburban‐urban streams. 49 72 streams studied. Uptake length due to ( S Wden n) ranged from 89 m 184 km (median 9050 m) there were no significant differences among regions or land‐use categories, likely because the wide range conditions within each region land use. N 2 production far exceeded O all The fraction total removal water 0.5%...
We conducted 15NO 3 − stable isotope tracer releases in nine streams with varied intensities and types of human impacts the upstream watershed to measure nitrate (NO ) cycling dynamics. Mean ambient NO concentrations ranged from 0.9 21,000 μg l−1 –N. Major N-transforming processes, including uptake, nitrification, denitrification, all increased approximately two three orders magnitude along same gradient. Despite increases transformation rates, efficiency which stream biota utilized...
Restoration of riparian vegetation is widely recognized as a tool in stream rehabilitation, but information on whether local characteristics can mitigate the effects catchment-level stressors in-stream processes limited. We measured community metabolism 21 streams Canterbury region New Zealand along 2 independent gradients agricultural intensity and cover (from closed canopied to open canopied) assess relative landscape factors trophic state. with single-station open-channel diel O2 method....
Wireless neural stimulators are being developed to address problems associated with traditional lead-based implants. However, designing wireless on the sub-millimeter scale (<1mm3) is challenging. As device size shrinks, it becomes difficult deliver sufficient power operate device. Here, we present a sub-millimeter, inductively powered stimulator consisting only of coil receive power, capacitor tune resonant frequency receiver, and diode rectify radio-frequency signal produce excitation. By...
Human modification of natural streams by urbanization has led to more homogeneous channel surfaces; however, the influence simplification on in situ microbial distribution and function is poorly characterized. For example, denitrification, a process that reduces soluble nitrogen (N) levels, requires peripheral anoxic zones might be lost artificial channels such as those with concrete lining. To examine how influenced simplification, we quantified denitrification rates conditions mats within...
Nutrient dynamics in rivers are central to global biogeochemistry. We measured ammonium (NH 4 + ) uptake, metabolism, nitrification, and denitrification the thalweg, river region of greatest flow, Kansas River (discharge = 14,360 L/s). estimated gross net uptake with a depleted 15 N‐NH release, metabolism diel O 2 measurements, dissolved N measurements. Net ecosystem production was negative. NH length 2.1 km when concentrations were elevated, 1.9 at ambient concentrations. Gross rate...
Abstract Electronic devices placed in the gastrointestinal (GI) tract for prolonged periods have potential to transform clinical evaluation and treatment. One challenge deployment of such gastroresident electronics is difficulty powering millimeter-sized without using batteries, which compromise biocompatibility long-term residence. We examined feasibility leveraging mid-field wireless transfer power from outside body at various locations along GI tract. Using simulations ex vivo...
A new approach for miniaturizing an ultra-wideband spiral antenna, called the periodic antenna (PSA), is presented. The combination of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\bm{z}}$</tex-math></inline-formula> -directed meandering element and a tapered substrate profile provides volumetric style miniaturization. In this design, distributed inductance capacitance, therefore impedance match, are...
Abstract Globally intensive agriculture has both increased nitrogen pollution in adjacent waterways and decreased availability of terrestrially derived carbon frequently used by stream heterotrophs cycling. We tested the potential for additions via leaf litter from riparian restoration plantings to act as a tool enhancing denitrification agricultural streams with relatively high concentrations nitrate (1.3–8.1 mg/L) Canterbury, New Zealand. Experimental packs (N = 200, mass 350 g each) were...
We conducted a series of stepwise NO3− additions to investigate the response uptake short-term (acute) changes in N concentration 3 prairie streams. Observed rates increased with elevations and were consistent linear Michaelis–Menten kinetics models. compiled these data from additional published studies calculate robust estimates for Half-saturation coefficients based on 6.7 µg/L NH4+ 67 NO3−-N. This difference half-saturation suggests that is more efficiently assimilated than NO3−,...
Summary 1. Nitrogen (N) processing in streams has been investigated using whole‐stream 15 N addition experiments that, general, have found that a large proportion of added nitrate removed from the water column appears to be assimilated by stream benthos. The long‐term fate this retained is unknown, and particular interest possibility it becomes denitrified through coupled mineralisation–nitrification–denitrification processes (indirect denitrification). 2. We used situ chambers produce...
Abstract Potentially toxic levels of 3 naturally occurring chemical stressors (dissolved sulfide, ammonia, and iron) can appear in freshwater sediments, although their roles shaping ecosystem structure (i.e., plant animal communities) function (e.g., biologically mediated elemental cycles) have received little study. The present critical review discusses the prevalence ecological effects potentially concentrations iron uncontaminated including a literature as well case study presenting...
Summary 1. We used two separate approaches to estimate ambient ammonium cycling in the north and south branches of Kings Creek, a prairie stream. Chamber experiments were conducted determine uptake mineralization rates associated with epilithic biofilms filamentous algae collected from streams. A series short‐term whole‐stream addition also rate at stream concentrations, based on relationship between concentrations rates. 2. scaled up levels, resulting gross estimates 0.08 μ g −2 s −1 for...
Recent developments in peripheral nerve electrodes allow the efficient and selective neuromodulation of somatic autonomic nerves, which has proven beneficial specific bioelectronic medical applications. However, current most clinical devices are wired powered by implantable batteries suffer from several limitations. We recently developed a sub-millimeter inductively neural stimulator (electroparticle; EP), this study, we report integration EP onto commercial cuff (EP-C) allowing wireless...
Traditional productivity‐diversity theory predicts that eutrophication will result in greater species richness due to increased resources at the bottom of food web. However, few studies on effects increasing ecosystem productivity biological communities have included responses multiple trophic levels. We hypothesized effect would vary between different levels shifts community composition and interactions. To investigate mechanisms driving productivity‐richness relationships, we constructed...
We used pulsed and continuous additions of 15 N together with whole‐ecosystem metabolism measurements to elucidate the mechanisms nitrogen (N) transformations in a small (1170 m 2 ) through‐flow wetland situated along stream. From inflow outflow, we observed consistent decrease nitrate (by 10% concentrations), while ammonium increased by an order magnitude. Outflow concentrations oscillated diel cycle, inverse concentration dissolved oxygen (i.e., greater export at night). The showed little...