79717 research outputs found
Sort by
HixonMarkZoologyComparativeBehaviorRed(VOR).pdf
No full textPacific red lionfish Pterois volitans have invaded Atlantic reefs and reached much greater population densities than on native reefs. We hypothesized that lionfish on invaded reefs would (1) experience higher kill rates and thus spend less time hunting, given the naïveté of Atlantic prey, (2) consume a greater variety of prey, given the lack of native prey defenses, and (3) display less pronounced crepuscular patterns of hunting, given the ease of capturing Atlantic prey. Comparative behavioral observations were conducted in 2 native regions (Philippines and Guam) and 2 invaded regions (Cayman Islands and Bahamas) to assess lionfish time budgets and diurnal activity patterns and to explore correlations between environmental variables and lionfish behavior. Contrary to our first hypothesis, total time allocated to hunting and kill rates showed no difference between native and invaded reefs, despite considerable regional variation. However, Atlantic prey of lionfish were twice as large as Pacific prey, suggesting that despite similar hunting behavior, invasive lionfish ingest greater daily rations of prey biomass. Furthermore, consistent with our second hypothesis, lionfish on invaded reefs had broader diets, and also relied less on ‘blowing’ behavior for prey capture, pointing to substantial prey naïveté in the invaded range. Importantly, only in the invaded range did we observe lionfish consuming parrotfishes, the decline of which could have indirect effects on interactions between seaweeds and corals. Finally, lionfish overall tended to exhibit a crepuscular pattern in behavior whereby hunting peaked at sunrise and/or sunset, with no differences attributable to native vs. invasive status
Oregon State Forester ; Vol. 34, No. 1 (January 1982)
No full textMagazine of the OSU Forestry Alumni Association.Keywords: Dick Dilworth, Forest Science, Forest Management, Forestry Media Center, Class Reunions, Forest Engineering, Focus on Future, With The Classes, Forestry Students Association, School Forests, Recognition, Careers in Forestry, Forest Products, 75th Anniversary, Resource Recreation Managemen
Catch shares, fisheries, and ecological stewardship: a comparative analysis of resource responses to a rights-based policy instrument
Full text linkRights-based approaches are potentially promising tools to meet conservation objectives in natural resource management. Here, we evaluated how population status and fishery production respond to catch shares, a rights-based policy instrument in fisheries whereby participants are granted a right to harvest a fraction of the allowable catch. By analyzing time series of landings, exploitation rate, and population biomass for >150 fisheries, we find that catch shares tended to dampen variance in fishery landings and exploitation rate, that they had no effect on population biomass, and that the responses were unrelated to population status prior to catch shares. Variance dampening was strongest when harvesting rights were durable and secure but was absent otherwise. Reductions in exploitation rate were strongest in multispecies fisheries with high levels of at-sea observers. Although benefits are not guaranteed, successful catch share programs share common elements that can be incorporated in the design of future programs.Keywords: marine conservation, Catch shares, market-based approaches, fisheries, policy evaluation, property-rightsKeywords: marine conservation, Catch shares, market-based approaches, fisheries, policy evaluation, property-right
PisiasNicklasCEOASMultivariateStatisticalAnalysis.pdf
No full textMultivariate statistical treatments of large data sets in sedimentary geochemical and other fields are
rapidly becoming more popular as analytical and computational capabilities expand. Because
geochemical data sets present a unique set of conditions (e.g., the closed array), application of generic
off-the-shelf applications is not straightforward and can yield misleading results. We present here
annotated MATLAB scripts (and specific guidelines for their use) for Q-mode factor analysis, a
constrained least squares multiple linear regression technique, and a total inversion protocol, that are
based on the well-known approaches taken by Dymond (1981), Leinen and Pisias (1984), Kyte et al.
(1993), and their predecessors. Although these techniques have been used by investigators for the past
decades, their application has been neither consistent nor transparent, as their code has remained in-house
or in formats not commonly used by many of today’s researchers (e.g., FORTRAN). In addition to
providing the annotated scripts and instructions for use, we discuss general principles to be considered
when performing multivariate statistical treatments of large geochemical data sets, provide a brief
contextual history of each approach, explain their similarities and differences, and include a sample data
set for the user to test their own manipulation of the scripts.Keywords: geochemistry, multivariate statistics, statisticsKeywords: geochemistry, multivariate statistics, statisticsKeywords: geochemistry, multivariate statistics, statisticsKeywords: geochemistry, multivariate statistics, statistic
Presentation.pdf
No full textFamily influence in the home environment has been linked to children’s nutrition and physical activity behaviors. However few tools exist to identify family level behaviors and families’ readiness to change those behaviors, particularly for populations at high risk for obesity such as Hispanics. This study summarizes the relationships of similar items between a newly created family obesity-preventing behavior screening tool (Family Stage of Change [FSOC] Survey), and a validated screening tool that measures both family and child-level behaviors shown to predict child obesity (Family Nutrition and Physical Activity [FNPA] screening tool). Of particular interest for this study was whether responses on these surveys differed between Hispanic and non-Hispanic families to determine potential validity of the FSOC instrument for use with Hispanic families. Study participants included parents and caregivers (N=66) of children ages 2-14 years recruited through preschool, elementary, and middle school listservs and through word of mouth. Descriptive analyses were conducted on the demographic data, and correlations were run to examine associations between FSOC and FNPA items. Mean Domain, and Total scores were analyzed for differences between Hispanic and non-Hispanic responders. After stratifying respondents by education level, a second set of correlations was conducted to better understand the role of education on participant responses. Moderate to strong correlations were observed between the
individual items (0.33 to 0.97, p<0.05). When correlations were examined by education level, the strength of several correlations decreased substantially with the lowest correlations observed among those with the lowest education level. Significant differences were also examined between FNPA and FSOC domain scores. On the FNPA Hispanics had lower FNPA mean summary score relative to Eating Behaviors (EB; 19 + 3.3 vs. 20.6 + 1.8, p=0.02)) and Screen Time Behaviors (ST; 6.1 + 1.7 vs. 6.9 + 1.5, p=0.04). On the FSOC Hispanics had lower mean individual and mean summary scores in the PA and Sleep Behavior domains (p<0.05). In conclusion, additional research is needed to determine if the FSOC is a valid and reliable instrument and has the potential to meet an identified need related to family-directed, obesity prevention efforts for Hispanic families, or any families when the caregiver has low education.Keywords: Hispanics, Family Nutrition and Physical Activity Screening Tool, family home environment, Child obesity, obesity preventing behaviors, readiness to change, Family Stages of ChangeKeywords: Hispanics, Family Nutrition and Physical Activity Screening Tool, family home environment, Child obesity, obesity preventing behaviors, readiness to change, Family Stages of Chang
PaulikLaurenEMTImpactNaturalGas.pdf
No full textNatural gas extraction, often referred to as “fracking,” has increased rapidly in the U.S. in recent years. To address potential health impacts, passive air samplers were deployed in a rural community heavily affected by the natural gas boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. PAH levels were highest when samplers were closest to active wells. Additionally, PAH levels closest to natural gas activity were an order of magnitude higher than levels previously reported in rural areas. Sourcing ratios indicate that PAHs were predominantly petrogenic, suggesting that elevated PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. Closest to active wells, the risk estimated for maximum residential exposure was 2.9 in 10,000, which is above the U.S. EPA’s acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest. This work suggests that natural gas extraction may be contributing significantly to PAHs in air, at levels that are relevant to human health.Keywords: fracking, unconventional natural gas drilling, air quality, passive sampling, hydraulic fracturing, cancer risk assessmentKeywords: fracking, unconventional natural gas drilling, air quality, passive sampling, hydraulic fracturing, cancer risk assessmen
A Stochastic Frontier Model to Determine Technical Efficiency of the Purse Seine Fishery in the Gulf of Cadiz (Spain)
Full text linkIn this paper we analyse different econometric procedures of technical efficiency to estimate fishing capacity. These procedures are then applied to the purse seine fishery located in the Gulf of Cádiz. The target species of this fishery has changed quite a lot over the past few years. It used to be mackerel (Scomber spp.). Afterwards, it was anchovy (Engraulis encrasicholus) and, recently, sardine (Sardina pilchardus). The regulation of anchovy and sardine fisheries by European Union is only based on Total Allowable Catch for vessels which are longer than 10 metres. This management measure could be unsuitable in this fishery for two reasons. Firstly, most of the vessels measure less than 10 metres and, secondly, there is a small interrelation between vessel efficiency and length.Keywords: purse seine fishing, Stochastic frontiers, Theoretical and Empirical Bio-Economic Modelling, panel data, Fisheries Economics, Fishing capacity, Gulf of Cadiz, management policie
A Simulation Model for Epidemics of Stem Rust in Ryegrass Seed Crops
Full text linkA simulation model (STEMRUST_G, named for stem rust of grasses)
was created for stem rust (caused by Puccinia graminis subsp.
graminicola) in perennial ryegrass grown to maturity as a seed crop. The
model has a daily time step and is driven by weather data and an initial
input of disease severity from field observation. Key aspects of plant
growth are modeled. Disease severity is modeled as rust population
growth, where individuals are pathogen colonies (pustules) grouped in
cohorts defined by date of initiation and plant part infected. Infections
due to either aerial spread or within-plant contact spread are modeled.
Pathogen cohorts progress through life stages that are modeled as disease
cycle components (colony establishment, latent period, infectious period,
and sporulation) affected by daily weather variables, plant growth, and
fungicide application. Fungicide effects on disease cycle components are
modeled for two commonly used active ingredients, applied preinfection
or postinfection. Previously validated submodels for certain disease cycle
components formed the framework for integrating additional processes,
and the complete model was calibrated with field data from 10 stem rust
epidemics. Discrepancies between modeled outcomes and the calibration
data (log₁₀[modeled] – log₁₀[observed]) had a mean near zero but considerable
variance, with 1 standard deviation = 0.5 log₁₀ units (3.2-fold).
It appears that a large proportion of the modeling error variance may be
due to variability in field observations of disease severity. An action
threshold for fungicide application was derived empirically, using a
constructed weather input file favorable for disease development. The
action threshold is a negative threshold, representing a level of disease
(latent plus visible) below which damaging levels of disease are unable to
develop before the yield-critical crop stage. The model is in the public
domain and available on the Internet.Keywords: Lolium perenne, Decision aid, Azoxystrobin, Propiconazole, WheatKeywords: Lolium perenne, Decision aid, Azoxystrobin, Propiconazole, Whea
Observing and modeling the influence of layering on bubble trapping in polar firn
Full text linkInterpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau.This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/%28ISSN%292169-8996/.Keywords: ice core, firn density, layering, firn, total air content, methan
Katy Marvel Thesis Main Body.doc
No full textProstate cancer is the most commonly diagnosed cancer in men, but rates around the world vary greatly. Americans have the highest incidence rates in the world, 4 to 5 times those of Spain. The hypothesis of this thesis was that vitamin D metabolism is a factor in prostate cancer development and the aim was to examine differences in factors that modulate vitamin D metabolism between the US and Spain, specifically sunlight exposure and vitamin D receptor (VDR) polymorphisms. Through a search of papers that examined sunlight exposure and prevalence of VDR polymorphisms, we found that Spain had more ultraviolet exposure than the United States, but there was little difference in proportions of VDR polymorphisms between the two populations. TaqI, BsmI, and FokI polymorphisms of the VDR were studied. Proportions of TaqI and FokI were found to be equivalent between the two populations. The rates of BsmI polymorphisms were found to be statistically different, but the United States, not Spain, has higher proportions of the protective allele. With no apparent rate differences in the VDR polymorphisms these do not help explain the different prostate cancer rates. However, the increased sun exposure in Spain may allow more vitamin D production which could be a contributing factor for Spain having lower prostate cancer incidence rates.Keywords: Vitamin D receptor, Prostate cance