Sampling design for compliance monitoring of surface water quality: A case study in a Polder area

International agreements such as the EU Water Framework Directive (WFD) ask for efficient sampling methods for monitoring natural resources. In this paper a general methodology for designing efficient, statistically sound monitoring schemes is described. An important decision is the choice between a design-based and a model-based method, implying the choice between probability (random) sampling and purposive sampling. For mapping purposes, model-based methods are more appropriate, whereas to obtain valid results for the universe as a whole, such as in testing water quality standards against legal standards, we generally prefer a design-based method. Four basic sampling patterns in space-time universe are described: static, synchronous, static-synchronous, and rotational. A case study is carried out for monitoring the quality of surface water at two farms in western Netherlands, wherein a synchronous sampling design is applied, with stratified simple random sampling in both space and time. To reduce laboratory costs the aliquots taken at the locations of a given sampling round are bulked to form a composite. To test the spatiotemporal mean N-total concentration during the summer half-year against the MAR standard with a power of 80% at a concentration 15% below the MAR standard and with a confidence of 95%, six to nine sampling rounds are needed with 50 to 75 locations per sampling round. For P-total the required number of sampling rounds differs strongly between the two farms, but is for both farms much larger than for N-total

Monte Carlo and spatial sampling effects in regional uncertainty propagation analyses

Spatial uncertainty propagation analysis (UPA) aims at analysing how uncertainties in model inputs propagate through spatial models. Monte Carlo methods are often used, which estimate the output uncertainty by repeatedly running the model with inputs that are sampled from their probability distribution. Regional application of UPA usually means that the model output must be aggregated to a larger spatial support. For instance, decision makers may want to know the uncertainty about the annual nitrate leaching averaged over an entire region, whereas a model typically predicts the leaching for small plots. For models without spatial interactions there is no need to run the model at all points within the region of interest. A sufficiently large sample of locations may represent the region sufficiently well. The reduction in computational load can then be used to increase the number of Monte Carlo runs. In this paper we explore how a combination of analytical and numerical methods can be used to evaluate the errors introduced by Monte Carlo and spatial sampling. This is important to be able to correct for the bias inflicted by the spatial sampling, to determine how many model runs are needed to reach accurate results and to determine the optimum ratio of the Monte Carlo and spatial sample sizes

Estimating space-time mean concentrations of nutrients in surface waters of variable depth

A monitoring scheme has been designed to test whether the space-time mean concentration total Nitrogen (N-total) in the surface water in the Northern Frisian Woodlands (NFW, The Netherlands) complies with standards of the European Water Framework directive. Since in statistical testing for compliance monitoring valid estimators for the mean and its variance are important, a design-based method is preferred above a model-based method. In the NFW-area the surface water depth varies in both space and time and can periodically equal zero, due to variation in precipitation and evapotranspiration. To account for this, space-time mean concentrations are estimated by the ratio of the estimated total mass of nutrient and the estimated total volume of water. The method is applied in the period from 1 April to 30 September 2008 to four hydrologically different subareas. Besides, the aim was to use the information on the spatial and temporal variance of N-total concentrations to optimize the numbers of sampling rounds and sampling locations per sampling round in future monitoring campaigns, given budgetary constraints. A bootstrap procedure was applied to account for uncertainty about the temporal and spatial variances in estimating the optimal number of sampling rounds and sampling locations. For two subareas the accuracy of the estimated space-time means can be improved by sampling more frequently at less locations (compared to the design applied in 2008), whereas for one subarea sampling less frequently at more locations increases the precision. For one subarea the sample data were rather inconclusive about the optimal sample sizes

Group Education for patients with rheumatoid arthritis

Patients with rheumatoid arthritis must learn to adjust their exercise, rest and medication to the varying activity of the disease. Patient education can help patients in making the right decisions about adjustments in their treatment regimen and in attaining ¿self-management¿ behaviors. We developed a group education program based on social learning theory and the `Arthritis Self Management Course¿ developed in the USA by Lorig. Goal of the program is the strengthening of self-efficacy, outcome expectations and self-management behaviors of RA patients which may lead to better health status. The program has been evaluated in an experimental design. We established significant positive effects of the group training on functional disability, joint tenderness, practice of relaxation and physical exercises, self-management behavior, outcome expectations, self-efficacy function and knowledge. After 14 months we still found effects on practice of physical exercises, self-efficacy function and knowledge

Patient education and disease activity: A study among rheumatoid arthritis patients

Objective: To determine whether patients experiencing high disease activity derive more benefit from patient education than those experiencing low disease activity. - \ud Methods: Data from a randomized study on the effects of a program of patient education were analyzed retrospectively. Four subgroups were studied: the high disease activity subgroup of patients who had participated in the educational program, the complementary low disease activity subgroup, the high disease activity subgroup of controls, and its low disease activity complement. Patients with erythrocyte sedimentation rate >28 mm/first hour were classified as having high disease activity. Effects on frequency of physical exercises, endurance exercises, and relaxation exercises and effects on health status (Modified Health Assessment Questionnaire, Dutch Arthritis Impact Measurement Scales [AIMS]) were measured. - \ud Results: There were no significant differences between the adherence parameters of the various pairs of groups. Four months after the educational program began, anxiety and depression scores on the Dutch-AIMS had increased among participating patients who were experiencing high disease activity and decreased among those who were experiencing low disease activity. - \ud Conclusions: Patients experiencing high disease activity did not derive more benefit from patient education than those experiencing low disease activity. On the contrary, an increase of anxiety and depression is found in these patients. Further study is needed to confirm our findings

Comment on "Quantum Confinement and Optical Gaps in Si Nanocrystals"

We show that the method used by Ogut, Chelikowsky and Louie (Phys. Rev. Lett. 79, 1770 (1997)) to calculate the optical gap of Si nanocrystals omits an electron-hole polarization energy. When this contribution is taken into account, the corrected optical gap is in excellent agreement with semi-empirical pseudopotential calculations.Comment: 3 pages, 1 figur

Postglacial development of silver fir (Abies alba Mill.) in the territory of the present- day Slovenia

V prispevku so predstavljene raziskave, ki obravnavajo razširjenost navadne jelke (Abies alba Mill.) na ozemlju današnje Slovenije v pleistocenu in holocenu. Zbrani so podatki o paleobotaničnih ostankih (fosilni ostanki iz terciarja, pelod, makroskopski rastlinski ostanki) v paleolitskih postajah in o genetskih značilnostih današnjih jelovih populacij. V prispevku razpravljamo o možnem obstoju ledenodobnih zatočišč in lokalnem postglacialnem razvoju populacij jelke v Sloveniji.The paper reviews the research dealing with the presence of silver fir (Abies alba Mill.) within modern-day Slovenian territory in the Pleistocene and Holocene. The data on paleobotanical remains (Tertiary fossil remains, pollen,macroscopic plant remains) on Paleolithic sites and on genetic properties of the present silver fir populations are presented. The possible existence of glacial refugia and local postglacial development of silver fir populations in Slovenia are discussed

Site Visit to La Perouse

“When you walk here today, you walk among the spirits of our ancestors,” reads a brand-new Welcome To Country sign above the front desk of the La Perouse Museum, the text an evocative reminder of the resilience of Indigenous Australians in places where they have struggled for a voice. While this demonstrates a shift in recent years to acknowledging and valuing the Indigenous heritage of these places, an exploration of the museum makes the precedence given to eponymous explorer Lapérouse clear. This is a place where the French community has long celebrated their own place in Australia. However, despite their tens of thousands of years in the area, the addition of Aboriginal history is a recent one. If Aboriginal history can be considered a battlefield of conflicting accounts and perspectives, then the exhibits in this museum are the survivors of a long war