Changes In Frequency Of Occurrence Research Articles

Evaluating the effectiveness of teacher training in Applied Behaviour Analysis

Interventions for children with autism based upon Applied Behaviour Analysis (ABA) has been repeatedly shown to be related both to educational gains and to reductions in challenging behaviours. However, to date, comprehensive training in ABA for teachers and others have been limited. Over 7 months, 11 teachers undertook 90 hours of classroom instruction and supervision in ABA. Each teacher conducted a comprehensive functional assessment and designed a behaviour support plan targeting one behaviour for one child with an autistic disorder. Target behaviours included aggression, non-compliance and specific educational skills. Teachers recorded observational data for the target behaviour for both baseline and intervention sessions. Support plans produced an average 80 percent change in frequency of occurrence of target behaviours. Questionnaires completed by parents and teachers at the end of the course indicated a beneficial effect for the children and the educational environment. The potential benefits of teacher implemented behavioural intervention are discussed.

Multilevel Assessment of Fish Species Traits to Evaluate Habitat Degradation in Streams of the Upper Midwest

AbstractWe used species traits to examine the variation in fish assemblages for 21 streams in the Northern Lakes and Forests Ecoregion along a gradient of habitat disturbance. Fish species were classified based on five species trait‐classes (trophic ecology, substrate preference, geomorphic preference, locomotion morphology, and reproductive strategy) and 29 categories within those classes. We used a habitat quality index to define a reference stream and then calculated Euclidean distances between the reference and each of the other sites for the five traits. Three levels of species trait analyses were conducted: (1) a composite measure (the sum of Euclidean distances across all five species traits), (2) Euclidean distances for the five individual species trait‐classes, and (3) frequencies of occurrence of individual trait categories. The composite Euclidean distance was significantly correlated to the habitat index (r = −0.81; P = 0.001), as were the Euclidean distances for four of the five individual species traits (substrate preference: r = −0.70, P = 0.001; geomorphic preference: r = −0.69, P = 0.001; trophic ecology: r = −0.73, P = 0.001; and reproductive strategy: r = −0.64, P = 0.002). Although Euclidean distances for locomotion morphology were not significantly correlated to habitat index scores (r = −0.21; P = 0.368), analysis of variance and principal components analysis indicated that Euclidean distances for locomotion morphology contributed to significant variation in the fish assemblages among sites. Examination of trait categories indicated that low habitat index scores (degraded streams) were associated with changes in frequency of occurrence within the categories of all five of the species traits. Though the objectives and spatial scale of a study will dictate the level of species trait information required, our results suggest that species traits can provide critical information at multiple levels of data analysis.

Canopy Height Effects on Vaseygrass and Bermudagrass Spread in Limpograss Pastures

Potential grass weeds in limpograss [Hemarthria altissima (Poir.) Stapf & Hubb.] pastures include vaseygrass (Paspalum urvillei Steud) and common bermudagrass [Cynodon dactylon (L.) Pers.]. Grazing management is critical to controlling spread of these grasses and maintaining productive limpograss swards, but competition dynamics among these species have not been evaluated under grazing. The objective of this experiment was to determine the effect of grazed canopy height (20, 40, and 60 cm) of continuously stocked limpograss pastures on changes in frequency of occurrence and ground cover of limpograss, vaseygrass, and common bermudagrass and plant density of vaseygrass. Experimental units were 0.5‐ha pastures replicated four times in a completely randomized design. During the 2 yr of grazing, vaseygrass density decreased in all pastures, changing most for the 20‐cm canopy height and least for the 60‐cm canopy height (4.4 vs. 0.4 plants m−2). Changes in vaseygrass cover followed the same trend as density. In contrast, bermudagrass cover increased by seven percentage units if pastures were grazed to a 20‐cm height, but the increase was less for 40‐ and 60‐cm swards. These data show that continuous stocking of limpograss pastures decreased vaseygrass plant density, especially when canopy height was low; however, common bermudagrass invasion was favored by grazing to 20 cm, potentially compromising limpograss persistence. It is concluded that grazing continuously stocked limpograss pastures to approximately 40 cm is effective in decreasing existing populations of vaseygrass while minimizing invasion by common bermudagrass.

Polar mesospheric clouds: The year-to-year changes shown in 17 years of images from both hemispheres

Meteosat images recorded from December 1983 to December 2000 have been examined systematically to determine the year-to-year change in frequency of occurrence. The statistics from the southern hemisphere are poor because of what appears to be a systematic difference between the two hemispheres with the southern hemisphere showing many fewer days with polar mesospheric clouds present. There is some indication of a local time dependence in the occurrence of the clouds in the northern hemisphere which may arise from the passage of a planetary wave through the regions available for observation from geostationary orbit. There are eleven years in the data when night-to-night observations (NLC) from Europe of noctilucent clouds are available. Comparison of 341 nights using the NLC and the northern satellite data show no significant level of simultaneous occurrence.

Forest birds in forest fragments: are fragmentation effects independent of season?

The aim of this study was to examine whether effects of habitat fragmentation on forest birds persist across seasons. W e noted the presence or absence of 18 bird species in 16 wood plots on 12 occasions (six in winter and six in spring). Woodland area ranged between 0.5 and 200 ha. All patches consisted of mature deciduous woodland. Degree of fragmentation for each woodland patch was indexed by the factor scores on the first two axes resulting fvom a principal component analysis, performed on a number of area and isolation variables. Both in winter and in spring, species richness correlated negatively with degree of fragmentation. The number of species observed was higher in winter than in spring for most patches, but the difference was unrelated to the degree of fragmentation. On a species level, little evidence was found for an effect of interaction between season and degree of fragmentation on the frequency of occurrence. The effects of fragmentation seem to depend on season in the Great Spotted Woodpecker Dendrocopos major and the Treecreeper Certhia brachydactyla, but not in the other species considered. Fragmentation has a negative effect on the frequency of occurrence of the Nuthatch Sitta europaea, Goldcrest Regulus regulus, Treecreeper, Great Spotted Woodpecker and the Starling Sturnus vulgaris, and a positive effect for the Chaffinch Fringilla coelebs and, possibly, the Lesser Spotted Woodpecker Dendrocopos minor. Seasonal changes in frequency of occurrence were noted in four of the species considered.

Evaluation of the Effects of Nutrient Removal and the “Storm of the Century” on Submersed Vegetation in Kings Bay – Crystal River, Florida

ABSTRACT Municipal wastewater effluent was removed in 1992 from a cove (Cedar Cove) of Kings Bay in an attempt to reduce the bay's ambient total phosphorus (TP) and total nitrogen (TN) concentrations. Many citizens and professionals viewed nutrient removal as the solution to reducing the bay's nuisance growths of aquatic macrophytes and filamentous algae. Wastewater removal reduced average TP from 105 μg·L−1 to 27 μg·L−1 and average TN from 620 μg·L−1 to 220 μg·L−1 in Cedar Cove. TP (24 μg·L−1 to 28 μg·L−1) and TN (300 μg·L−1 to 260 μg·L−1), however, were not significantly reduced in southern Kings Bay. There were no significant changes in mean frequency of occurrence of vallisneria in Cedar Cove (0% to 1%) or southern Kings Bay (19% to 22%). Average hydrilla occurrence decreased significantly after wastewater removal in Cedar Cove (54% to 36%) and southern Kings Bay (61% to 35%). Eurasian watermilfoil occurrence significantly increased in Cedar Cove (6% to 24%) and southern Kings Bay (11 % to 32%). Filam...

Behavior of mitochondria in synchronized cells of Chlamydomonas reinhardtii (Chlorophyta).

Cells of Chlamydomonas reinhardtii Dangeard were synchronized under a 12 hour:12 hour light:dark regimen. Behavior of mitochondria in these cells was studied by fluorescence microscopy using a mitochondrial membrane-binding fluorescent dye, dimethylaminostyrylmethyl-pyridiniumiodine (DASMPI), as well as by electron microscopy. Following time courses of change in frequency of occurrence of five typical morphologies of mitochondria in synchronized cells, strikingly dynamic behavior of mitochondria was demonstrated. The five types are (A) a giant global mitochondrion with large matrix and peripherally localized cristae, a part of which is in close contact with the nucleus, (B) a mitochondrion composed of thick-corded bodies connected to each other, a part of which is in contact with the nucleus, (C) thin-corded forms with a few branches, (D) small lump forms scattered in the cytoplasm, and (E) stringy forms with intricate branchings extended throughout the cytoplasm. During the early half of the light period, changes of C-->B-->C-->D occur, while the inversely sequential changes of D-->C-->B-->C proceed during the later half of the light period. The appearance of the B-type mitochondrion is accompanied by a transient decrease of O2-uptake activity of cells. The early appearing B-type mitochondrion is temporarily turned into a giant A-type mitochondrion, concomitant with discharge of membranes into the cytoplasm and their retake by the A-type form in the process of reversion to B-type. In the reversion process, partitioning membranes are also formed in the large matrix of A-type mitochondrion.(ABSTRACT TRUNCATED AT 250 WORDS)

A method for investigating hepatocyte polyploidization kinetics during postnatal development in mammals

A method for investigating weakly-proliferating cell populations of liver parenchyma on the basis of a quantitative analysis of hepatocyte polyploidization during postnatal development is described. The method uses a mathematical model which characterizes the hepatocyte polyploidization process, and incorporates data concerning the time course for relative frequencies of hepatocytes in different ploidy classes. As a result of these measurements and calculations for rat liver, transition rates of hepatocytes (the relative number of cells during a given time unit) from one ploidy class to another, and a coefficient for the reduction of hepatocyte mitotic activity with an increase in its ploidy class were obtained. Calculated curves show a good correspondence with the real process of hepatocyte frequency changes as they relate to changes in the age of the animals. To check this method, experiments investigating time changes of autoradiographic label content in the different ploidy classes of hepatocytes were carried out. By mathematically modeling the label diluting process resulting from cell proliferation and polyploidization, transition rates of hepatocytes were calculated, and they reflect values calculated from the model according to changes in occurrence frequencies.

The diet of feral cats (Felis catusL.) on Hawke’s Bay farmland, New Zealand

Abstract Food remains were analysed in 361 cat faeces (scats) collected from September 1983 to May 1987 on farmland in southern Hawke’s Bay. Mammals were the most important food items in scats, both by occurrence (76%) and by weight (74%). House mice were the most frequently (50%) encountered remains, and comprised only 12% of the total prey identified by weight; rats were less frequently found (20%) but the most important item by weight (39%). Other mammals found were scavenged possums (13% by weight), sheep (7%), and lagomorphs (3%). Birds, consisting mainly of introduced species, including turkeys, were both frequent (24%) and important by weight (24%). Invertebrate remains consisted mainly of cicada nymphs (Homoptera) (10% by frequency), grass grubs (Coleoptera) (8%), and black field crickets (Orthoptera) (7%) contributed less than 2% by weight. Cicada nymphs were recorded only in willow/ swamp habitat. No significant differences were found between vertebrate prey recorded in scats from willows and swamps and vertebrate prey from bams and pasture. There were no consistent local or seasonal changes in frequency of occurrence of rats, but mice were found more frequently in scats collected in winter. Possum remains were found mainly in winter. Birds were the main items in scats collected in the spring and summer months. Eggs of Toxocari cati (64%) were the only identifiable internal parasite frequently found in the scats.

A storm surge origin for sandstone beds in an epicontinental platform sequence, Ordovician, Norway

The upper Ashgillian (Ordovician) sediments of the Oslo area were deposited on an extensive open marine platform. Within the sequence thin sandstones (0.5–10 cm thick) are interbedded with bioturbated silty shales. The beds commonly have sharp lower surfaces and more diffuse tops which suggest sand was rapidly introduced into a tranquil environment. Estimates suggest that the deposition of a sand bed was a very infrequent event, recurring every few thousand years. The sandstones show lateral changes in frequency of occurrence, and total cumulative thickness, which, taken together with palaeocurrent evidence, indicate derivation from the west. Vertical changes in thickness of sandstone per metre, mean bed thickness, bedforms and grain size all reflect an increasing proximality to a westerly sediment source and can be related to a shoreface with eastward longshore drift developed during the upper Ordovician regression. The general reconstruction of Ashgillian palaeogeography in the Oslo region suggests that the sand beds were deposited by currents flowing offshore, obliquely down a low palaeoslope. Most normal currents on modern continental shelves flow parallel to the shoreline, so we have considered other mechanisms which might have produced low-frequency, high-energy currents which flowed offshore and which could have been responsible for the deposition of the thin, discrete sandstones. Three models are discussed for the formation of the thin sandstones, and an ebb current generated by a storm surge is considered the most likely explanation.

The variability of edidetic imagery among Australian Aboriginal children.

Summary Variability in incidence of eidetic imagery (EI)—the so-called “will-o'-the-wisp” nature of EI—can be considered in two ways. Regularity of occurrence of EI can be studied across cultural communities and within individual cultural groups. The present study tested EI in a group of Aboriginal children who previously were reported as showing a high incidence of this form of imagery. It also contrasted the performance of this group with the performance of another community of Aboriginal children who were even more isolated than the Bamyili sample from Western influence. Variability was evidenced across the two communities, but the same incidence of EI was found within the Bamyili sample. The change in frequency of occurrence of EI across unacculturated samples remains the essential puzzle of the phenomenon of eidetic imagery.