Confidence Regions with Nuisance Parameters

Consider a distribution with several parameters whose exact values are unknown and need to be estimated using the maximum-likelihood technique. Under a regular case of estimation, it is fairly routine to construct a confidence region for all such parameters, based on the natural logarithm of the corresponding likelihood function. In this article, we investigate the case of doing this for only some of these parameters, assuming that the remaining (so called nuisance) parameters are of no interest to us. This is to be done at a chosen level of confidence, maintaining the usual accuracy of this procedure (resulting in about 1% error for samples of size , and further decreasing with 1/n). We provide a general solution to this problem, demonstrating it by many explicit examples.

Nuisance species:beyond the ecological perspective

Introduction:‘Nuisance species’(or‘invasive’species)are often proposed to be the second most important concern in the context of the current biodiversity crisis.Despite increasing evidence that exotic species do not always become invasive,this perception is still common in the scientific community.This suggests that other issues are at stake in the concept of nuisance species rather than just the problems they raise,grounded mostly in ecological or economic arguments.Methods:We retraced the evolution of pigeon representation in France through an extensive review of ancient texts related to pigeons and reviewed more than 240 source texts,dating from the seventh century to the 1990s.We completed these data with literature on human-animal relationships and animal conceptions in religious,philosophical,scientific,and political currents of thought that were representative of Western and,specifically,French tradition.Results:We used the heated debate over pigeons(Columba livia)as pests as a case study by analyzing the ecological,social,economic,and political relations regarding pigeons.Through a historical perspective of the debate about and understanding of pigeons,we propose a new and complementary explanation for the modern thinking of pigeons as a nuisance species,based on what we termed their socio-nature characteristics.In particular,we used social representations theory to highlight the issues of human identity construction at stake in the construction of pigeons as a nuisance species.Conclusions:We invite the reader to consider the impact of such human self-definition on environmental stances,as it could constrain further developments or improvements of conservation perspectives.

Constructing Confidence Regions for Autoregressive-Model Parameters

We discuss formulas and techniques for finding maximum-likelihood estimators of parameters of autoregressive (with particular emphasis on Markov and Yule) models, computing their asymptotic variance-covariance matrix and displaying the resulting confidence regions;Monte Carlo simulation is then used to establish the accuracy of the corresponding level of confidence. The results indicate that a direct application of the Central Limit Theorem yields errors too large to be acceptable;instead, we recommend using a technique based directly on the natural logarithm of the likelihood function, verifying its substantially higher accuracy. Our study is then extended to the case of estimating only a subset of a model’s parameters, when the remaining ones (called nuisance) are of no interest to us.

Assessment of anti mosquito measures in households and resistance status of Culex species in urban areas in southern Ghana:Implications for the sustainability of ITN use

Objective:To determine resistance status of Culex species to different class of insecticides and assess the major anti-mosquito strategies employed by urban households and their possible effects on malaria acquisition.Methods:Structured questionnaires were randomly administered to obtain information on demographic characteristics,measures that people use to prevent mosquito bites and their perception of where mosquitoes breed in their communities.Adult susceptibility assays were also carried out using WHO discriminating dosages of four insecticides from different chemical classes against Culex species.Results:Majority of respondents(54.75%) preferred the use of domestic insecticides in the form of aerosols and coils.Among households that used domestic insecticides,the use of coil was most frequent(62.9%) with a mean(95%CI) of 9.18(8.99,9.37) coils per week.Strong level of pyrethroid-resistance and multiple insecticide resistance in Culex species were also detected in some of the study sites.Conclusions:The excessive use of domestic insecticides and high level of resistance in Culex species observed in the study area has implications for the ITN component of the nation's malaria control program in more subtle ways.People will lose interest in the use of ITN when it fails to protect users from bites of resistant Culex species.Excessive use of domestic insecticides may also select resistance in both malaria vectors and Culex species.On this account we recommend that nuisance mosquitoes must be controlled as part of malaria control programs to improve acceptance and utilization of ITN.

Professional Stress Factor of Vulnerability in Which Has Occurred of the Road Traffic Accidents at a Sample of Drivers in Morocco

The professional stress is a physical and emotional harmful reaction. In fact, it presents a major public health problem in Morocco. Our work is directed to study the differences between the various groups of professional and non-professional drivers in terms of stress reactions, noise nuisance and implication in the production accidents. The present study is transversal descriptive type based on a questionnaire and neuropsychological tests conducted by 60 non-professional drivers and 60 taxi drivers in Kenitra. Two scales evaluated the stress: the Resistance Test of Stress (TRS) and the Perceived Stress Scale (PSS). According to this last scale, 63.5% of the taxi drivers were considered as stressed. These drivers have the following specific components: mood trouble, sleep trouble, pressure of time, work boredom, stress sensation and tiredness at the end of driving. 65% of drivers take a pause after 5 to 6 hours of work. According to the Test of Resistance at the Stress, the taxi driver’s populations are more homogeneous but are less likely to resist stress compared to their non-professionals counterparts. Indeed to work on the professional stress requires a qualitative and quantitative approach phenomenon allowing a more complete vision. This study sheds new light on the understanding of stress at work by using new measurement and evaluation methods such as TRS, with an aim to reduce or to eliminate the number of road accident.

Modelling Dust Emissions from a Source Using Dust Monitoring and Meteorological Data

This paper describes a study into the development of more robust dust emission factors by means of dust and meteorological monitoring. Emission factors for nuisance dusts in the literature are scarce, with estimates of dust output given for many processes in mass per unit area per year. Temporal variations and the extent and conditions in which maximum concentrations occur can therefore be impossible to predict with any accuracy. This investigation aims to improve predic-tions by “back calculating” emission levels based on dust monitoring around known dust sources. Nuisance dust and meteorological monitoring has been undertaken at a sand and gravel quarry in the UK for a consecutive period of two years. Sticky pad directional dust monitors were used to collect dust at eight locations at and around the site with meteorological data collected at an elec-tronic weather station within the site. Air quality modelling software (ADMS) was used to test emission factors from the European Environment Agency (EEA) and the US Environmental Protec-tion Agency (EPA) for emissions from mineral workings. Predictions were compared with the dust monitoring data to assess accuracy, with results showing limited poor correspondence (r2 < 0.3). Trends showed that emission predictions were poorest in winter;this is likely because most emis-sion calculations are not weather dependent and seasonal fluctuations will occur. Dust emission rate calculations were altered with respect to the dust monitoring data for one monitoring location on the mineral site boundary and the model was run again. Results were then tested at two different locations up to 200 m from the site boundary, with very positive correlations (r2 0.89) and similar maximum concentrations (<5% difference). This study has therefore shown that ac-curate site-specific emission rates can be produced in combination with site boundary sticky pad dust monitoring in order to accurately derive estimations elsewhere.

Comparative study of the effect of Bacillus thuringiensis on larval populations of Culex pipiens L.(Diptera-Culicidae)of the City of Tlemcen(Algeria)

In the cities of Algeria, Culex pipiens L. (Diptera: Culicidae) is the mosquito which presents most interest because of its wide geographical distribution and of its abundance which engender a strong nuisance. Besides, its role of vector of the virus West Nile arouses a particular interest in the Mediterranean Basin. These insects are generally controlled by conventional insecticides for the greater part, chemicals which cause in the long term side effects (effects on the not aimed bodies and the resistance of the aimed species). A research for the effect of the bioinsecticide Bacillus thuringiensis (granulated commercial shape in 200 IUT1/mg) was realized on préimaginales populations of the artificial deposits sites (taken directly of them natural the deposits sites) and cleansed populations (stemming from a breeding) having never been handled previously, taking into account local weather and physico-chemical conditions. Analyses of variance, allowed to determine the combined effect of the factor measure and of the factor time which by increasing, increase the efficiency of the product. The results of the rates of mortalities registered after treatment allowed to loosen the DL50 and the DL90 for every embryonic stage. From the results, we estimated the degree of sensibility of the larva populations of Culex pipiens which have proved heterogeneous in partial tolerance in Bacillus thuringiensis for the populations of the sensitive artificial and homogeneous the deposits sites for those stemming from the breeding.