A comparison of vacuum sampling versus sweep-netting for arthropod biodiversity measurements in California coastal sage scrub

The recent growth of conservation biology has demanded that faster and more effective measures of biodiversity be utilized. Arthropods, due to high levels of diversity and their relative ease of capture, are often the subject of such surveys. The vacuum sampler, used quite often in the context of agricultural arthropod surveys, has never been adequately evaluated or compared to more traditional collection techniques in relatively complex ecosystems. The purpose of this study was to determine whether the vacuum sampler was more or less effective than a sweep-net in measuring arthropod biodiversity in California coastal sage scrub. The results show that significantly more individuals were collected by the vacuum sampler per unit effort for three out of six orders of arthropods examined. In addition, the vacuum sampler collected a significantly greater number of arthropod species than the sweep-net technique for two out of the six orders sampled. There were no significant differences in the number of species collected for the remaining four orders. We feel these findings are important for arthropod biodiversity studies utilized for conservation efforts as the vacuum sampler can attain a level of efficiency and sensitivity (with regard to species detection) that sweep-net techniques cannot. © Rapid Science Ltd. 1998     

Response to selection for litter size in Danish Landrace pigs: a Bayesian analysis

A replicated selection experiment aimed at increasing litter size (total number of pigs born per litter) in Danish Landrace pigs was conducted from 1984 to 1991. The experiment included two selection and two control lines. In each generation, 30 and 14 first litters were produced in selection and control lines, respectively, and dams produced two litters. Each replicate, consisting of one selection and one control line, was founded from 60 families chosen randomly from the population at large. Family selection was practiced, and the criterion was the predicted breeding value for litter size computed using a repeatability animal model, and taking into account all available information. The data consisted of 947 records from 523 dams (424 dams had two litters) representing five cycles of selection of increased litter size. Data were analyzed from a Bayesian perspective, based on marginal posterior distributions of genetic parameters of interest. Marginalization was achieved using Gibbs sampling, with a single chain length of 1 205 000. After discarding the first 5 000 iterations, a sample was drawn every ten iterations, so 120 000 samples in total were saved. Densities were estimated and plotted, and summary statistics were computed from the estimated densities. The posterior means (± standard error) of heritability and repeatability were 0.22 ± 0.06 and 0.32 ± 0.05, respectively. These point estimates of genetic parameters were within the range of literature values, although on the high side. The posterior mean (± standard error) of genetic response to selection, defined as the difference between the mean breeding values of the selected lines and that of the base population, was 1.37 ± 0.43 pigs after five cycles of selection. The regression (through the origin) of breeding values in the selected lines on generation was 0.25 ± 0.08 pigs. Several informative priors constructed from information obtained with field data in this population were used to examine their influence on inferences. The priors were influential because of the relatively small scale of the experiment. An analysis excluding data from one of the control lines gave smaller genetic variance and heritability, and a smaller response to selection. However, it appears that selection for litter size is effective, but that the true rate of response is probably smaller than data from this experiment suggest.     

Random effects in censored ordinal regression: latent structure and Bayesian approach

This paper discusses random effects in censored ordinal regression and presents a Gibbs sampling approach to fit the regression model. A latent structure and its corresponding Bayesian formulation are introduced to effectively deal with heterogeneous and censored ordinal observations. This work is motivated by the need to analyze interval-censored ordinal data from multiple studies in toxicological risk assessment. Application of our methodology to the data offers further support to the conclusions developed earlier using GEE methods yet provides additional insight into the uncertainty levels of the risk estimates.     

A transformation approach for incorporating monotone or unimodal constraints

Samples of curves are collected in many applications, including studies of reproductive hormone levels in the menstrual cycle. Many approaches have been proposed for correlated functional data of this type, including smoothing spline methods and other flexible parametric modeling strategies. In many cases, the underlying biological processes involved restrict the curve to follow a particular shape. For example, progesterone levels in healthy women increase during the menstrual cycle to a peak achieved at random location with decreases thereafter. Reproductive epidemiologists are interested in studying the distribution of the peak and the trajectory for women in different groups. Motivated by this application, we propose a simple approach for restricting each woman's mean trajectory to follow an umbrella shape. An unconstrained hierarchical Bayesian model is used to characterize the data, and draws from the posterior distribution obtained using a Gibbs sampler are then mapped to the constrained space. Inferences are based on the resulting quasi-posterior distribution for the peak and individual woman trajectories. The methods are applied to a study comparing progesterone trajectories for conception and nonconception cycles.     

Aerobiological monitoring applications in the Etnean volcanic plume evaluation (Mt. Etna, Sicily) and correlation with allergopathies

This paper describes the study of the application of a Hirst-type impact volumetric sampler (IVS) in the sampling of volcanic ash continuously emitted by Mt. Etna. This methodology is commonly used for measuring the atmospheric concentration of airborne pollen grains and fungal spores. This study was undertaken between April 2003 and January 2005, when a series of ash emissions occurred; moreover, during this period, namely on 7 September 2004, there was an eruption from various fractures located in the higher eastern flank of the volcano. The airborne volcanic ashes involving the lower south-eastern flank of Mt. Etna were monitored by means of an IVS stationed in the town of Acireale. In some people volcanic ash can trigger predisposing factors linked with allergens, and an allergic response may occur. After exposure, immunoglobulin E (IgE) antibodies are produced and released into the bloodstream and they can, therefore, be identified by haematological analysis. In this study we compared the number of ash events recorded by our IVS and the number of total immunoglobulin E (IgE) values found in the population living on or near this volcano sector. A correlation was established between air pollution from volcanic ash and IgE values over a period of 22 months.     

Pollen texture identification using neural networks

The importance of research leading to the automation of pollen identification is briefly outlined. A new technique, neural network analysis, is briefly introduced, and then applied to the determination of light microscope images of pollen grains. The results are compared with some previously published statistical classifiers. Although both types of classifiers may work, the neural network is apparently superior to the statistical methods in three ways: high success rates (100% in this case), small number of samples needed for training, and simplicity of features.     

Pollen concentrations inside private cars during the Poaceae and Artemisia spp. pollen season – a case study

A growing number of studies are researching indoor air concentrations of pollen in buildings, but to our knowledge no studies have dealt with the precise concentration of pollen inside private cars. The aim of this study was to assess the risk of exposure to pollen in private cars throughout the Poaceae and Artemisia spp. pollen season.

The study was conducted in the town of Lappeenranta and along Highway 6 in south‐east Finland between July 14 and August 17, 2003. The pollen concentrations were measured inside two moving and parked cars using rotorod‐type samplers. Surface and ambient Burkard samples were also collected.

Both Poaceae and Artemisia spp. pollen were recorded only on one day and in low concentrations (<10 pollen grains per cubic meter, pg/m³) inside moving and parked cars, whereas the concentrations of Betula spp. (0–15 vs. 0–12?pg/m³) and Pinus (0–41 vs. 0–80?pg/m³) ranged from low to moderate, respectively. The number of pollen grains on the inside surfaces of cars ranged from zero to 72?pg/cm² during the measurement periods.

The concentrations of Poaceae and Artemisia spp. pollen in the indoor air of the car during the flowering period were low, therefore, likely to cause reactions only in the most sensitive people. By contrast, even after the main flowering period the concentrations of Betula spp. pollen were on a level high enough to cause reactions in individuals with allergies.     

Indoor and outdoor pollen concentrations in private and public spaces during the <Emphasis Type="Italic">Betula</Emphasis> pollen season

Although the number of studies of pollen concentrations inside and outside buildings is increasing, little is known about the efficiency of penetration of pollen from outdoor to indoor air, and further. We studied indoor and outdoor pollen concentrations in the town of Lappeenranta and in the municipality of Rautjärvi in SE Finland from May 3–23, 2004, i.e. throughout the Betula pollen season, and assessed the risk of exposure to pollen grains. Pollen concentrations were measured inside and outside a block of flats, a detached house, and the regional central hospital, using rotorod-type samplers; in the town of Joutseno data were compared with Burkard counts. Outdoor concentrations of Betula pollen grains ranged between low and abundant (0–855 grains m^?3). The corresponding indoor concentrations near the main front doors varied from low to moderate (0–17 grains m^?3) in the central hospital and were low (<10 grains m^?3) in both residential buildings. Indoor concentrations further from the main front door were low (<10 grains m^?3) at all study sites. The concentrations of Betula pollen decreased substantially from outdoors to indoors, and further toward the centre of the building, probably indicating relatively poor penetrating properties of the pollen grains and/or the short-lived presence of pollen grains in indoor air. The concentrations of Betula pollen inside the buildings during the peak flowering period were mostly at a level barely inducing reactions even in the most sensitive persons.