8 resultados para Job demand-resources model
em DigitalCommons@University of Nebraska - Lincoln
Resumo:
We propose an efficient scheduling scheme that optimizes advance-reserved lightpath services in reconfigurable WDM networks. A re-optimization approach is devised to reallocate network resources for dynamic service demands while keeping determined schedule unchanged.
Resumo:
1. The crabeater seal Lobodon carcinophaga is considered to be a key species in the krill-based food web of the Southern Ocean. Reliable estimates of the abundance of this species are necessary to allow the development of multispecies, predator–prey models as a basis for management of the krill fishery in the Southern Ocean. 2. A survey of crabeater seal abundance was undertaken in 1500 000 km2 of pack-ice off east Antarctica between longitudes 64–150° E during the austral summer of 1999/2000. Sighting surveys, using double observer line transect methods, were conducted from an icebreaker and two helicopters to estimate the density of seals hauled out on the ice in survey strips. Satellite-linked dive recorders were deployed on a sample of seals to estimate the probability of seals being hauled out on the ice at the times of day when sighting surveys were conducted. Model-based inference, involving fitting a density surface, was used to infer densities in the entire survey region from estimates in the surveyed areas. 3. Crabeater seal abundance was estimated to be between 0.7 and 1.4 million animals (with 95% confidence), with the most likely estimate slightly less than 1 million. 4. Synthesis and applications. The estimation of crabeater seal abundance in Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) management areas off east Antarctic where krill biomass has also been estimated recently provides the data necessary to begin extending from single-species to multispecies management of the krill fishery. Incorporation of all major sources of uncertainty allows a precautionary interpretation of crabeater abundance and demand for krill in keeping with CCAMLR’s precautionary approach to management. While this study focuses on the crabeater seal and management of living resources in the Southern Ocean, it has also led to technical and theoretical developments in survey methodology that have widespread potential application in ecological and resource management studies, and will contribute to a more fundamental understanding of the structure and function of the Southern Ocean ecosystem.
Resumo:
Preservation of rivers and water resources is crucial in most environmental policies and many efforts are made to assess water quality. Environmental monitoring of large river networks are based on measurement stations. Compared to the total length of river networks, their number is often limited and there is a need to extend environmental variables that are measured locally to the whole river network. The objective of this paper is to propose several relevant geostatistical models for river modeling. These models use river distance and are based on two contrasting assumptions about dependency along a river network. Inference using maximum likelihood, model selection criterion and prediction by kriging are then developed. We illustrate our approach on two variables that differ by their distributional and spatial characteristics: summer water temperature and nitrate concentration. The data come from 141 to 187 monitoring stations in a network on a large river located in the Northeast of France that is more than 5000 km long and includes Meuse and Moselle basins. We first evaluated different spatial models and then gave prediction maps and error variance maps for the whole stream network.
Resumo:
Wildlife biologists are often interested in how an animal uses space and the habitat resources within that space. We propose a single model that estimates an animal’s home range and habitat selection parameters within that range while accounting for the inherent autocorrelation in frequently sampled telemetry data. The model is applied to brown bear telemetry data in southeast Alaska.
Resumo:
Black bears (Ursus americanus) forage selectively in natural environments. To determine if bears also forage selectively for anthropogenic resources we analyzed data on vehicles broken into by bears from Yosemite National Park, California. We classified vehicles into 9 categories based on their make and model and collected data on use (2001–2007) and availability (2004–2005). From 2001 to 2007 bears broke into 908 vehicles at the following rates: minivan (26.0%), sport–utility vehicle (22.5%), small car (17.1%), sedan (13.7%), truck (11.9%), van (4.2%), sports car (1.7%), coupe (1.7%), and station wagon (1.4%). Only use of minivans (29%) during 2004–2005 was significantly higher than expected (7%). We discuss several competing hypotheses about why bears selected minivans.
Resumo:
Objective: To determine current food handling practices, knowledge and beliefs of primary food handlers with children 10 years old and the relationship between these components. Design: Surveys were developed based on FightBac!™ concepts and the Health Belief Model (HBM) construct. Participants: The majority of participants (n= 503) were females (67%), Caucasians (80%), aged between 30 to 49 years old (83%), had one or two children (83%), prepared meals all or most of the time (76%) and consumed meals away from home three times or less per week (66%). Analysis: Descriptive statistics and inferential statistics using Spearman’s rank correlation coefficient (rho) (p<0.05 and one-tail) and Chi-square were used to examine frequency and correlations. Results: Few participants reached the food safety objectives of Healthy People 2010 for safe food handling practices (79%). Mixed results were reported for perceived susceptibility. Only half of the participants (53-54%) reported high perceived severity for their children if they contracted food borne illness. Most participants were confident of their food handling practices for their children (91%) and would change their food handling practices if they or their family members previously experienced food poisoning (79%). Participants’ reasons for high self-efficacy were learning from their family and independently acquiring knowledge and skills from the media, internet or job. The three main barriers to safe food handling were insufficient time, lots of distractions and lack of control of the food handling practices of other people in the household. Participants preferred to use food safety information that is easy to understand, has scientific facts, causes feelings of health-threat and has lots of pictures or visuals. Participants demonstrate high levels of knowledge in certain areas of the FightBac!TM concepts but lacked knowledge in other areas. Knowledge and cues to action were most supportive of the HBM construct, while perceived susceptibility was least supportive of the HBM construct. Conclusion: Most participants demonstrate many areas to improve in their food handling practices, knowledge and beliefs. Adviser: Julie A. Albrecht
Resumo:
Abstract Small-scale coffee producers worldwide remain vulnerable to price fluctuations after the 1999-2003 coffee crisis. One way to increase small-scale farmer economic resilience is to produce a more expensive product, such as quality coffee. There is growing demand in coffee-producing and coffee-importing countries for user-friendly tools that facilitate the marketing of quality coffee. The purpose of this study is to develop a prototypical quality coffee marketing tool in the form of a GIS model that identifies regions for producing quality coffee in a country not usually associated with quality coffee, Honduras. Maps of areas for growing quality coffee were produced with information on climate, soils, topography, areas vulnerable to environmental degradation, the location of current quality coffee farms, and infrastructure. The maps depict suitable coffee-growing land in portions of eight western Honduran departments.
Resumo:
To open this Third Vertebrate Pest Conference is a real privilege. It is a pleasure to welcome all of you in attendance, and I know there are others who would like to be meeting with us, but, for one reason or another cannot be. However, we can serve them by taking back the results of discussion and by making available the printed transactions of what is said here. It has been the interest and demand for the proceedings of the two previous conferen- ces which, along with personal contacts many of you have with the sponsoring committee, have gauged the need for continuing these meetings. The National Pest Control Association officers who printed the 1962 proceedings still are supplying copies of that conference. Two reprintings of the 1964 conference have been necessary and repeat orders from several universities indicate that those proceedings have become textbooks for special classes. When Dr. Howard mentioned in opening the first Conference in 1962 that publication of those papers would make a valuable handbook of animal control, he was prophetic, indeed. We are pleased that this has happened, but not surprised, since to many of us in this specialized field, the conferences have provided a unique opportunity to meet colleagues with similar interests, to exchange information on control techniques and to be informed by research workers of problem solving investigations as well as to hear of promising basic research. The development of research is a two-way street and we think these conferences also identify areas of inadequate knowledge, thereby stimulating needed research. We have represented here a number of types of specialists—animal ecologists, public health and transmissible disease experts, control methods specialists, public agency administration and enforcement staffs, agricultural extension people, manufacturing and sale industry representatives, commercial pest control operators, and others—and in addition to improving communications among these professional groups an equally important purpose of these conferences is to improve understanding between them and the general public. Within the term general public are many individuals and also organizations dedicated to appreciation and protection of certain animal forms or animal life in general. Proper concepts of vertebrate pest control do not conflict with such views. It is worth repeating for the record the definition of "vertebrate pest" which has been stated at our previous conferences. "A vertebrate pest is any native or introduced, wild or feral, non-human spe- cies of vertebrate animal that is currently troublesome locally or over a wide area to one or more persons either by being a general nuisance, a health hazard or by destroying food or natural resources. In other words, vertebrate pest status is not an inherent quality or fixed classification but is a circumstantial relationship to man's interests." I believe progress has been made in reducing the misunderstanding and emotion with which vertebrate pest control was formerly treated whenever a necessity for control was stated. If this is true, I likewise believe it is deserved, because control methods and programs have progressed. Control no longer refers only to population reductions by lethal means. We have learned something of alternate control approaches and the necessity for studying the total environment; where reduction of pest animal numbers is the required solution to a problem situation we have a wider choice of more selective, safe and efficient materials. Although increased attention has been given to control methods, research when we take a close look at the severity of animal damage to so many facets of our economy, particularly to agricultural production and public health, we realize it still is pitifully small and slow. The tremendous acceleration of the world's food and health requirements seems to demand expediting vertebrate pest control to effectively neutralize the enormous impact of animal damage to vital resources. The efforts we are making here at problem delineation, idea communication and exchange of methodology could well serve as both nucleus and rough model for a broader application elsewhere. I know we all hope this Third Conference will advance these general objectives, and I think there is no doubt of its value in increasing our own scope of information.