• Aims: Six sampling alternatives were examined for their ability to quantify selected attributes of snags and hardwoods in conifer-dominated riparian areas of managed headwater forests in western Oregon.
• Methods: Each alternative was simulated 500 times at eight headwater forest locations based on a 0.52-ha square stem map. The...
Measurements of the U₃₇ K’ index and the absolute abundance of alkenones in marine sediments are increasingly used in paleoceanographic research as proxies of past sea surface
temperature and haptophyte (mainly coccolith-bearing species) primary productivity, respectively. An
important aspect of these studies is to be able to compare reliably data...
Importance sampling algorithms are discussed in detail, with an emphasis on implicit sampling, and applied to data assimilation via particle filters. Implicit sampling makes it possible to use the data to find high-probability samples at relatively low cost, making the assimilation more efficient. A new analysis of the feasibility of...
We propose three sampling-based motion planning algorithms for generating informative mobile robot trajectories. The goal is to find a trajectory that maximizes an information quality metric (e.g. variance reduction, information gain, or mutual information) and also falls within a pre-specified budget constraint (e.g. fuel, energy, or time). Prior algorithms have...
Christmas tree needle sampling to evaluate nutrient need is an established practice. Data to support the recommended fall sampling time in Oregon and Washington was not found. In addition, the recommendation for needle sampling of Fraser fir in North Carolina was made without data from winter months. The goal for...
Sequestering semi-polar compounds can be difficult with low-density polyethylene (LDPE), but those pollutants may be more efficiently absorbed using silicone. In this work, optimized methods for cleaning, infusing reference standards, and polymer extraction are reported along with field comparisons of several silicone materials for polycyclic aromatic hydrocarbons (PAHs) and pesticides....
Pressurized liquid extraction (PLE) was evaluated as a method for extracting semivolatile organic compounds (SOCs) from air sampling media; including quartz fiber filter (QFF), polyurethane foam (PUF), and a polystyrene divinyl benzene copolymer (XAD-2). Hansen solubility parameter plots were used to aid in the PLE solvent selection in order to...
n-Tree distance sampling (NTDS), also known as k-tree sampling and point-to-tree sampling, has been promoted as a practical method for forest inventory. This simulation study evaluated the performance of three NTDS estimators, as compared with fixed plot sampling and horizontal point sampling, for estimating density and basal area in headwater...
Radiocarbon is an exceptionally useful tool for studying soil-respired CO₂, providing information about soil
carbon turnover rates, depths of production, and the biological sources of production through partitioning. Unfortunately, little
work has been done to thoroughly investigate the possibility of inherent biases present in current measurement techniques,
like those present...
Respondent-driven sampling (RDS) is used throughout the world to estimate prevalence and population size for hidden populations. Although RDS is an effective method for enrolling people from key populations in studies, it relies on a partially unknown sampling mechanism, and thus each individual’s inclusion probability is unknown. Current estimators for...