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An efficient method to estimate processing rates in streams
Get PDFWe provide an efficient method to estimate processing rates through simple algebraic relationships derived from the transient storage model equations. The method is based on the transport equations, but eliminates the need to calibrate highly uncertain (and intermediate) parameters. We demonstrate that under some common stream transport conditions dispersion does not play an important role in the estimation of processing rates and, therefore, can be neglected. Under such conditions, no computer modeling is needed to estimate processing rates. We also derive algebraic equations to estimate processing rates of target solutes (such as dissolved oxygen) with proxy-tracers (such as resazurin), and show that even if both the target and proxy reactions happen in exactly the same locations at rates that are linearly proportional, the exact relationship between the two volume-averaged rates can be nonlinear and a function of transport. However, the uncertainty in the estimation of the target processing rate is linearly proportional to the proxy-tracer processing rate.Keywords: decay, processing, streams, transient storage, hyporheic zone, uptak
Influences of Biological and Adoptive Mothers’ Depression and Antisocial Behavior on Adoptees' Early Behavior Trajectories
Get PDFResearch clearly demonstrates that parents pass risk for depression and antisocial behavior on to their children. However, most research confounds genetic and environmental mechanisms by studying genetically related individuals. Furthermore, most studies focus on either depression or antisocial behavior in parents or children, despite evidence of co-occurrence and shared etiology, and few consider the early origins of these problems in childhood. We estimated the influence of biological and adoptive mothers’ depression and antisocial behavior on growth in child externalizing and internalizing behaviors across early childhood using data from a prospective adoption study. Participants were 346 matched triads of physically healthy children (196 boys; 150 girls), biological mothers (BM), and adoptive mothers (AM). Latent growth curve models were estimated using AM reports of child internalizing and externalizing behaviors at ages 18, 27, and 54 months. Predictors of intercept (18 months) but not slope were identified. BM lifetime histories of major depressive disorder predicted child externalizing behaviors and BM antisocial behavior predicted child internalizing behavior. AM depressive symptoms and antisocial behavior were associated with both child outcomes. AM paths, but not BM paths were partially replicated using adopted fathers’ reports of child outcomes. BM obstetric complications, prenatal depressive symptoms, and postnatal adoptive family contact with BM did not account for BM paths. This adoption study distinguished risks conferred by biological mothers’ depression and antisocial behavior to children’s behaviors from those associated with adoptive mothers’ related symptoms. Future studies should examine gene-environment interplay to explain the emergence of serious problem trajectories in later childhood.Keywords: depression, externalizing, adoption, genetic risk, early childhood, internalizin
Absolute humidity modulates influenza survival, transmission, and seasonality
Get PDFInfluenza A incidence peaks during winter in temperate regions. The basis for this pronounced seasonality is not understood, nor is it well documented how influenza A transmission principally occurs. Previous studies indicate that relative humidity (RH) affects both influenza virus transmission (IVT) and influenza virus survival (IVS). Here, we reanalyze these data to explore the effects of absolute humidity on IVT and IVS. We find that absolute humidity (AH) constrains both transmission efficiency and IVS much more significantly than RH. In the studies presented, 50% of IVT variability and 90% of IVS variability are explained by AH, whereas, respectively, only 12% and 36% are explained by RH. In temperate regions, both outdoor and indoor AH possess a strong seasonal cycle that minimizes in winter. This seasonal cycle is consistent with a wintertime increase in IVS and IVT and may explain the seasonality of influenza. Thus, differences in AH provide a single, coherent, more physically sound explanation for the observed variability of IVS, IVT and influenza seasonality in temperate regions. This hypothesis can be further tested through future, additional laboratory, epidemiological and modeling studies.Keywords: droplet nuclei, virus survival, vapor pressure, aeroso
The optimal time path for carbon abatement and carbon sequestration under uncertainty : the case of stochastic targeted stock
Get PDFWe explore the optimal time path of carbon sequestration and carbon abatement in stabilizing CO₂ levels under uncertainty of climate impacts. Using a two-period sequential decision making model, we analytically derive optimal rates for the two control variables, abatement and sequestration rates. Uncertainty is assumed to affect the desired future stabilization level of the CO₂ stock but is resolved prior to the decision on how much to control the stock in the second period. Contrary to recent numerical studies, we find that uncertainty can make it optimal to use carbon sequestration either earlier or later depending on the relative rates of change in both marginal cost curves and on the amount of land that can be converted to forest. Comparative statics suggest that an increase in the discount factor could either increase or decrease the optimal rate of sequestration in the first period depending on the expected rate of change of the marginal cost of sequestration in the second period and on future benefits of current sequestration.Keywords: dynamic optimization, carbon sequestration, climate change, economics, uncertaint
Biochar production and applications in sub-Saharan Africa: Opportunities, constraints, risks and uncertainties
Get PDFSub-Saharan Africa (SSA) experiences soil degradation, food and livelihood insecurity, environmental pollution and lack of access to energy. Biochar has gained international research attention, but few studies have investigated the potential of biochar to address the challenges in SSA. This paper seeks to identify and evaluate generic potential opportunities and constraints associated with biochar application in sub-Saharan Africa using Zimbabwe as case study. Specific objectives were to; (1) identify and quantify feedstocks for biochar production; (2) review literature on the biochar properties, and evaluate its potential applications in agriculture, environmental remediation and energy provision, and (3) identify research gaps, risks and constraints associated with biochar technology. Biochar feedstocks in Zimbabwe were estimated to be 9.9 Mt yr⁻¹, predominantly derived from manure (88%) and firewood (10%). This will yield 3.5, 1.7 and 3.1 Mt yr⁻¹ of biochar, bio-oil and synthetic gas, respectively. Land application of the 3.5 Mt yr⁻¹ of biochar (≈63% C) would sequester approximately 2.2 Mt yr⁻¹ of soil carbon in Zimbabwe alone, while simultaneously minimizing the environmental and public health risks, and greenhouse gas emissions associated with solid organic wastes. Biochar potentially enhances soil and crop productivity through enhanced nutrient and soil moisture availability, amelioration of acidic soils and stimulation of microbial diversity and activity. Due to its excellent adsorption properties, biochar has potential applications in industrial and environmental applications including water and wastewater treatment, remediation and revegetation of contaminated soils and water. Biochar products have energy values comparable or higher than those of traditional biomass fuels; thereby making them ideal alternative sources of energy especially for poor households without access to electricity. Before the benefits of biochar can be realized in SSA, there is need to overcome multiple risks and constraints such as lack of finance, socio-economic constraints including negative perceptions and attitudes among both researchers and consumers, and environmental and public health risks. Therefore, there is need to conduct fundamental research to demonstrate the benefits of biochar applications, and develop policy framework and criteria for its production and subsequent adoption.Keywords: Energy provision, Carbon sequestration, Smallholder agroecosystems, Zimbabwe, Climate change, Pyrolysis, Biochar, Crop productivit
Thermal regime of the Costa Rican convergent margin: 1. Along‐strike variations in heat flow from probe measurements and estimated from bottom‐simulating reflectors
Get PDFThe thermal structure of convergent margins provides information related to the tectonics, geodynamics,
metamorphism, and fluid flow of active plate boundaries. We report 176 heat flow measurements
made with a violin bow style probe across the Costa Rican margin at the Middle America Trench. The
probe measurements are collocated with seismic reflection lines. These seismic reflection lines show widespread
distribution of bottom‐simulating reflectors (BSRs). To extend the spatial coverage of heat flow
measurements we estimate heat flow from the depth of BSRs. Comparisons between probe measurements
and BSR‐derived estimates of heat flow are generally within 10% and improve with distance landward of
the deformation front. Together, these determinations provide new information on the thermal regime of
this margin. Consistent with previous studies, the margin associated with the northern Nicoya Peninsula
is remarkably cool. We define better the southern boundary of the cool region. The northern extent of the cool region remains poorly determined. A regional trend of decreasing heat flow landward of the
deformation front is apparent, consistent with the downward advection of heat by the subducting Cocos
Plate. High wave number variability at a scale of 5–10 km is significantly greater than the measurement
uncertainty and is greater south of the northern Nicoya Peninsula. These heat flow anomalies vary between
approximately 20 and 60 mW m−2 and are most likely due to localized fluid flow through mounds and
faults on the margin. Simple one‐dimensional models show that these anomalies are consistent with flow
rates of 7–15 mm yr−1. Across the margin toe variability is significant and likely due to fluid flow through
deformation structures associated with the frontal sedimentary prism.Keywords: fluid flow, Subduction zones, Middle America trench, Heat flo
Measuring your trees workbook
No full textThis workbook is a companion to OSU Extension publication EM 9058, Measuring Your Trees. Before using this workbook, collect data following the procedures outlined in EM 9058. Then enter your data in this workbook to automatically calculate several stand volume and growth measurements and generate a printable summary report.Keywords: forest inventory, stand volume, mean annual increment, stand density, stand growth, tarif tree, tarif access table, volume projection, volume table, periodic annual increment, plot treePublished April 2013. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Buoyancy-Driven Coastal Currents off Oregon during Fall and Winter
Get PDFDuring fall/winter off the Oregon coast, oceanographic surveys are relatively scarce because of rough
weather conditions. This challenge has been overcome by the use of autonomous underwater gliders deployed
along the Newport hydrographic line (NH-Line) nearly continuously since 2006. The discharge from the
coastal rivers between northern California and the NH-Line reach several thousands of cubic meters per
second, and the peaks are comparable to the discharge from the Columbia River. This freshwater input
creates cross-shelf density gradients that together with the wind forcing and the large-scale Davidson Current
results in strong northward velocities over the shelf. A persistent coastal current during fall/winter, which the
authors call the Oregon Coastal Current (OCC), has been revealed by the glider dataset. Based on a two-layer
model, the dominant forcing mechanism of the OCC is buoyancy, followed by the Davidson Current and then
the wind stress, accounting for 61% (±22.6%), 26% (±18.6%), and 13% (±11.7%) of the alongshore
transports, respectively. The OCC average velocities vary from 0.1 to over 0.5 m s⁻¹, and transports are on
average 0.08 (±0.07) Sverdrups (Sv; 1 Sv = 10⁶ m³ s⁻¹), with the maximum observed value of 0.49 Sv, comparable
to the summertime upwelling jet off the Oregon coast. The OCC is a surface-trapped coastal current,
and its geometry is highly affected by the wind stress, consistent with Ekman dynamics. The wind stress has an
overall small direct contribution to the alongshore transport; however, it plays a primary role in modifying the
OCC structure. The OCC is a persistent, key component of the fall/winter shelf dynamics and influences the
ocean biogeochemistry off the Oregon coast.Keywords: Fronts, Density currents, Coastal flows, Circulation/Dynamics, Baroclinic flows, Freshwater, Runoff, Atm/Ocean Structure/Phenomen
Antenna Characterization for Bluetooth-based Travel Time Data Collection
Get PDFSeveral approaches for travel time data collection based on the reading of time-stamped media access control addresses from Bluetooth-enabled devices have been reported in the literature recently. This new approach offers a number of advantages over more conventional methods, including lower costs of hardware and software, the volume of data that can be collected over time, and ease of implementation.
A fundamental component that may affect the quantity and the quality of the travel time samples collected with a Bluetooth-based system is the antenna type utilized. Antenna characteristics such as polarization and gain must be matched to specific application environments to optimize the performance of a Bluetooth reader unit. However, experimental data that focuses on antenna characterization as it relates to the use of Bluetooth technology to assess the performance of transportation facilities is lacking.
In this study, five different types of antennas were characterized to assess their suitability to support a Bluetooth-based travel time data collection system. The results indicate that vertically polarized antennas with gains between 9dBi and 12dBi are good candidates for travel time data collection. Also, different antenna types are better suited to different uses of the Bluetooth-based system. If the main focus is the collection of travel time data, then an antenna with a lower sampling rate may provide more accurate travel time samples.Keywords: Gain, Antenna, MAC address, Polarization, Travel time, Bluetoot
Genetic resources for advanced biofuel production described with the Gene Ontology
Get PDFDramatic increases in research in the area of microbial biofuel production coupled with
high-throughput data generation on bioenergy-related microbes has led to a deluge of
information in the scientific literature and in databases. Consolidating this information and
making it easily accessible requires a unified vocabulary. The Gene Ontology (GO) fulfills that
requirement, as it is a well-developed structured vocabulary that describes the activities
and locations of gene products in a consistent manner across all kingdoms of life. The
Microbial ENergy processes Gene Ontology (http://www.mengo.biochem.vt.edu) project
is extending the GO to include new terms to describe microbial processes of interest
to bioenergy production. Our effort has added over 600 bioenergy related terms to the
Gene Ontology. These terms will aid in the comprehensive annotation of gene products
from diverse energy-related microbial genomes. An area of microbial energy research
that has received a lot of attention is microbial production of advanced biofuels. These
include alcohols such as butanol, isopropanol, isobutanol, and fuels derived from fatty
acids, isoprenoids, and polyhydroxyalkanoates. These fuels are superior to first generation
biofuels (ethanol and biodiesel esterified from vegetable oil or animal fat), can be generated
from non-food feedstock sources, can be used as supplements or substitutes for gasoline,
diesel and jet fuels, and can be stored and distributed using existing infrastructure. Here
we review the roles of genes associated with synthesis of advanced biofuels, and at the
same time introduce the use of the GO to describe the functions of these genes in a
standardized way.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by the Frontiers Research Foundation. The published article can be found at: http://www.frontiersin.org/Microbiology. Supplementary Material can be found at: http://www.frontiersin.org/journal/10.3389/fmicb.2014.00528/.Keywords: Gene Ontology, Advanced biofuels, Synthetic biology, Fatty acid-derived fuel, Advanced alcohols, Cellulosome, Isoprenoid-derived fue