bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of computer animation on the particulate mental models of college chemistry students
Authors: Williamson Vickie M. , Abraham Michael R.
Published: October 2006

Modern chemistry concepts have the particulate nature of matter at their core. Chemists explain most phenomena in terms of atomic and molecular models. The lack of understanding of chemistry concepts may be linked to the students' inability to build complete mental models that visualize particulate behavior. With computer animation technology, dynamic and three‐dimensional presentations are possible. This study explores the effect of computer animations depicting the particulate nature of matter on college students' mental models of the chemical phenomena. A Particulate Nature of Matter Evaluation Test (PNMET) instrument was used to determine the nature of the students' visualizations and, therefore, their comprehension of the chemical concept studied. Animations were used in two treatment situations: (a) as a supplement in large‐group lectures, and (b) as both the lecture supplement and an assigned individual activity in a computer laboratory. These two experimental treatments were compared to a control group. Both treatment groups received significantly higher conceptual understanding scores on the PNMET than did the control group. This increased understanding may be due to the superiority of the formation of more expertlike, dynamic mental models of particle behavior in these chemical processes.
Instructional strategy change and the attitude and achievement of seventh‐ and eighth‐grade science students
Authors: Houtz Lynne E.
Published: October 2006

This sequential methodologic elaboration study investigated differences between the middle school and the junior high instructional strategies and the effects on adolescent attitude toward science in school and science achievement. Subjects of the quantitative phase were 570 seventh‐ and eighth‐grade students in one school in an urban school district in the midwest United States during a transition year from junior high to middle school. Germann's Attitude toward Science in School Assessment and the school district's Benchmark Exams were employed to measure student pre‐ and posttest attitude and achievement. Variations within grade level, gender, race, general ability, and socioeconomic group were evaluated. Results of split plots revealed no significant differences in science attitude between the experimental middle school group and the junior high control group at this phase. However, there was significant improvement in attitude in both seventh‐grade populations, but no change in attitude in either eighth‐grade population. No significant differences in attitude were found between males and females, Caucasian students and students of color, or students of different ability or socioeconomic groups. Significant increases in science achievement were revealed in the seventh‐grade junior high control group, the eighth‐grade middle school, and the eighth‐grade junior high, but not in the seventh‐grade middle school. No significant differences in achievement were found between males and females. Caucasians scored significantly higher in achievement than students of color. Average and high ability students scored significantly higher pretest to posttest, but low ability students did not. High ability students scored significantly higher than both average and low ability groups. There was significant improvement in science achievement for students in the sufficient socioeconomic status group, but not in the low socioeconomic status group. These results were discussed with the five science teachers, the principal, and a university consultant in the setting, who were the informants of the qualitative elaboration phase of the study. Ethnographic methods uncovered themes explaining differences and similarities within the two instructional strategies. Teachers' feelings and stages of concern were identified. The results are discussed in terms of effectively implementing changes in instructional strategies and assessing science achievement of early adolescents.
A study of urban middle school students with high and low attitudes toward science
Authors: Atwater Mary M. , Wiggins John , Gardner Catherine M.
Published: October 2006

Scientific literacy is essential to survive in this technological world, but it appears that scientific literacy is not of high priority for many students. This research project was undertaken to gather demographic data, intentions to engage in science, and attitudes of urban, middle school students. Scores on the Simpson‐Troost Attitude Instrument were analyzed using the Statistical Analysis System. Results indicate less than 50% of the students come from high‐school‐graduated parents who work full‐time to support the family. Less than 50% of these students indicate any interest to engage in science at the high school level, yet many plan to enter a science‐related career. A majority of the students possess an uncertain attitude toward their science teachers and science curricula. However, all possessed high achievement motivations, strong positive attitudes toward their families, and high self‐concepts.
Lions and tigers and bears, oh my! children's conceptions of forests and their inhabitants
Authors: Strommen Erik
Published: October 2006

Forty first‐grade children, drawn from urban areas in Nebraska and New Jersey, were asked to produce drawings of forests and were interviewed about forests and the types of living things found in them. Results indicate that the children's concepts of animals and where they live are quite diverse, but highly concrete and unorganized. Although children correctly assigned most forest‐dwellers to the forest (deer and squirrels, for example), they also tended to assign almost all other animals (elephants, sharks, etc.) to the forest as well, especially carnivores. A general lack of awareness of plant life, insects, water resources, and other forest features was also observed.
Children's application of simultaneous and successive processing in inductive and deductive reasoning problems: Implications for developing scientific reasoning skills
Authors: Watters James J. , English Lyn D.
Published: October 2006

The research reported in this article was undertaken to obtain a better understanding of problem solving and scientific reasoning in 10‐year‐old children. The study involved measuring children's competence at syllogistic reasoning and in solving a series of problems requiring inductive reasoning. Children were also categorized on the basis of levels of simultaneous and successive synthesis. Simultaneous and successive synthesis represent two dimensions of information processing identified by Luria in a program of neuropsychological research. Simultaneous synthesis involves integration of information in a holistic or spatial fashion, whereas successive synthesis involves processing information sequentially with temporal links between stimuli. Analysis of the data generated in the study indicated that syllogistic reasoning and inductive reasoning were significantly correlated with both simultaneous and successive synthesis. However, the strongest correlation was found between simultaneous synthesis and inductive reasoning. These findings provide a basis for understanding the roles of spatial and verbal‐logical ability as defined by Luria's neuropsychological theory in scientific problem solving. The results also highlight the need for teachers to provide experiences which are compatible with individual students' information processing styles.
Concept mapping for the development of medical curricula
Authors: Edmondson Katherine M.
Published: October 2006

Increased use of problem‐based approaches to medical education has highlighted the challenges of curricular revision and interdisciplinary development. Venturing beyond disciplinary boundaries can be difficult, despite a desire to create interdisciplinary courses and adopt new ways of teaching. Concept mapping is an effective tool for developing an integrated curriculum. This article includes examples of concept maps that represent an entire veterinary curriculum, specific courses, and case‐based exercises. The author argues that concept mapping is a valuable tool for curriculum development of any scope or discipline, but is particularly helpful for creating interdisciplinary courses and case‐based exercises.
Nature of worldview presuppositions among science teachers in botswana, indonesia, japan, nigeria, and the philippines
Authors: Ogunniyi Meshach B. , Jegede Olugbenro J. , Ogawa Masakata , Yandila Cephas D. , Oladele Femi K.
Published: October 2006

The focus of this study was to identify the nature of worldview presuppositions held by a group of science teachers from five non‐western cultures. The results show that the subjects, irrespective of their cultural backgrounds, hold identical worldview presuppositions. It is not clear at this exploratory stage to what extent the subjects' alternative viewpoints influenced their scientific outlook or their science teaching. However, an analysis of the subjects' viewpoints suggests either poor conceptualizations of the nature of science or a form of collateral thinking, whereby an individual accepts or uses both mechanistic and anthropomorphic explanations depending on the context in question and without exhibiting any sign of cognitive dissonance. The implications of such a scenario for the teaching‐learning process are highlighted.
An empirical examination of the effects of family commitment in education on student achievement in seventh grade science
Authors: Wang Jianjun , Wildman Louis
Published: October 2006

A national data base from the Longitudinal Study of American Youth (LSAY) was employed to examine the effects of family commitment in education on student achievement in seventh grade science. The backward elimination procedure in the Statistical Analysis System (SAS) was adopted in this study to select significant variables of family commitment at α = .05. The results show that around 22% of the variance in student science achievement can be explained by the selected significant LSAY variables. An analysis of the impact of family commitment seems to indicate that parental education and encouragement are important factors in the improvement of student achievement. However, educators, including school personnel and parents, should exercise caution regarding how they help students with their homework and how they reward students for good grades.
Levels in Learning
Authors: Korthagen Fred , Lagerwerf Bram
Published: October 2006

In 1957, Van Hiele published his study on levels in learning mathematics. In this article we present an elaboration of the theory on levels in learning and an illustration of this theory based on empirical results. We distinguish between three levels: The first is the formation of an image out of a range of familiar examples or experiences. Second, on the basis of the image a schema can be built, which includes all kinds of interrelated details. Third, a theory can be developed with basic assumptions, definitions, and logical inferences. Before entering the next level, the learner should be sufficiently experienced on the actual level. It is shown that the theory on levels in learning can be integrated with other learning principles, such as notions from constructivism.
Pit‐relocation of antlion larvae in relation to their density
Authors: Matsura Toshiaki , Takano Hiroyuki
Published: October 2006

Of the biotic factors potentially affecting the foraging behavior of pit‐building antlion larvae, Myrmeleon boreTjeder, we focussed on the density effects and examined experimentally influences of larval density on pit construction behavior, spatial distribution and pit relocation rate. Moreover the mechanism of mutual interference among larvae was examined.

After releasing 2, 5, 10, 15, 20 and 30 third instar larvae of M. bore at the center of each container (30×30×10 cm3) filled with sand, we measured number of pits, pit diameter and position of pit base.

More than 80% of antlion larvae at each density always constructed pits, and the rates of larvae that had not constructed pits rose in proportion to the density. Pit size was approximately constant independent of the density.

The density of M. bore larvae clearly affected the residence time of the pits, i.e. more larvae frequently relocate pits with increasing larval density.

To analyze the spatial distribution pattern of the larvae in a container, nearest neighbor distance (NND) was measured. Comparison between the observed NND and the expected value for NND in random distribution obtained from computer simulation suggested that high larval density produced a uniform distribution owing to their mutual interference.

The result of an experiment to examine the mechanism of mutual interference among larvae showed that frequent dropping of sand into a pit tossed by neighbor antlion larvae causes a pit‐relocation.
Movement patterns of three Athalia sawflies in relation to the spatio‐temporal distributions of their habitats
Authors: Nagasaka Koukichi
Published: October 2006

I compared the differences in the movement intensity of three species of sympatric Athalia sawflies, A. japonica, A. rosae and A. infumata feeding on cruciferous plants. Mark‐release‐recapture census was conducted to estimate movement distance, sex ratio and age composition of adult sawflies. In addition, the sex ratio of newlyemerged adults was examined by rearing field‐collected larvae until adult emergence. Age composition and longevity of adults were estimated experimentally. The movement intensity was evaluated mostly with the indirect information thus obtained.

Females moved more actively than males in all three sawflies. A. japonica females of all age classes moved actively in spring and autumn, but in summer they disappeared. Also, A. rosae females of all age classes moved actively in spring and autumn. In summer, in contrast with A. japonica, A. rosae females moved most actively among the three species in all seasons. A. infumata females, in particular the young females, moved most actively among the three species, except A rosae in summer.

The movement patterns of the three sawflies were deduced in relation to the spatio‐temporal distributions of their habitats. In spring and autumn, when host plants were abundant, A. japonica and A. rosae females were dispersed among the host patches within the census are. In summer, however, when host plants were scarce, A. japonica entered diapause, whereas A. rosae migrated to neighboring areas. On the other hand, A. infumata, in particular young famale, innately dispersed to seek for temporary host plants throughout the census seasons.
‘Predator‐foolhardiness’ in an epidemic cicada population
Authors: Nagamine Masaaki , Itô Yosiaki
Published: October 2006

‘Predator‐foolhardiness’ (Lloyd andDybas, 1966b) in an epidemic population of the sugarcane cicada, Mogannia minuta was tested by counting the number of successful and failed trials of hand‐capturing of adults in the centre and periphery of a heavily infested area. Males frequently failed to escape from capture in the outbreak area but they did not in the peripheral zone. Females could escape well irrespective of the density. It was considered that the ‘predator‐foolhardiness’ of males is not due to genetic differentiation through the process of outbreak but to the effect of massive chorus on the escape behaviour.
Relation of transition probabilities in the Leslie model to those from experimental cumulative distributions
Authors: Yu Yanan , Gold Harvey J. , Stinner Ronald E.
Published: October 2006

We explore the relationship between transition probabilities in the Leslie model and those derived from experimental cumulative distributions. The nature of the two kinds of probabilities are discussed, and a formula derived for converting from one to the other. A numerical example is given to illustrate the differences.
A galling aphid with extra life‐cycle complexity: Population ecology and evolutionary considerations
Authors: Wool David , Burstein Moshe
Published: October 2006

In most gall‐forming aphids, only the fundatrix is able to induce a gall on the host plant. In Smynthurodes betae Westw. (and a few other species), F2 descendants emerge from the mother gall and induce their own, morphologically different galls. This constitutes an added complexity to the already very complex life cycle of gall‐forming aphids.

We investigated the ecology of S. betae on marked trees and shoots at four sites in Israel. Gall initiation, gall distribution and density, and temporal changes in clone size within the galls were investigated during two consecutive years. We discuss the possibility that the two‐gall life cycle evolved from the typical one‐gall system of most gall aphids, and the possible selective advantage of this added complexity in the life‐history strategy of gall aphids. Although the total reproductive output of S. betae is not higher than in related species with a single gall per life cycle, there seems to be an advantage in the subdivision of each aphid clone into several galls, thus reducing the risk of the accidental extinction of the clone (genotype) by environmental factors, including parasites and predators.
Effects of gall volume on survival and fecundity of gall‐making aphids Adelges japonicus (Homoptera: Adelgidae)
Authors: Ozaki Kenichi
Published: October 2006

The number of larvae reaching maturity within the gall of Adelges japonicus was positively related to gall volume, and the relationship between the number of mature larvae and gall volume did not change with different densities of colonized larvae.

The population changes in the bud galls of A. japonicus were surveyed by collecting the galls, which did not suffer predation or parasitism within the galls, from young artificial plantations of Picea jezoensis over two years. In the year when the density of colonized larvae was high, they suffered a 42% mortality within the galls, whereas mortality was nearly zero in the low density year. The numbers of larvae per gall were positively correlated with gall volume. The regression lines of the number of colonized larvae on gall volume did not differ significantly in the regression coefficients between the two years, whereas the intercept was significantly higher in the year when the density of colonized larvae was higher. However, different within‐gall mortality nullified this difference, and the regression lines of the number of mature larvae on gall volume had no significant difference both in the regression coefficients and the intercepts. This suggests that the number of mature larvae per gall was limited by available resources within the gall which were positively related to gall volume. In 25% of the galls in which mature larvae inhabited, the space within the galls were completely filled by the larvae, indicating that space was one of the limiting resources. Gall volume also affected the number of adults that emerged from the gall and the potential number of their progeny.
Population regulation by dispersal over patchy environment;
Authors: Nakano Tatsuhiko
Published: October 2006

A mathematical model for the population regulation is presented, which takes into account the environmental heterogeneity and the animal dispersal, and does not contain any direct density effect on reproduction or death processes. Generally speaking, there are two kinds of dispersal, one is the density independent dispersal, the other is the density dependent. It is shown that a population equilibrium can be maintained by the density dependent dispersal or threshold dispersal which occurs only when the population density exceeds a certain threshold level, but that density independent dispersal by itself can not continue to maintain a population equilibrium.
Contest and scramble competitions in two bruchid species, Callosobruchus analis andC. phaseoli (Coleoptera: Bruchidae)
Authors: Toquenaga Yukihiko , Fujii Koichi
Published: October 2006

Larval competition between contest and scramble strategists was investigated using the two bruchid species, C. analis (contest species) and C. phaseoli (scramble species) with two different sized mung beans (large and small beans). In both sized beans, the adult emergences of each species dependen on total density of the initial larval densities of the two species and the ratio of the two densities. The emergence of one species was suppressed by the existence of the other species when the initial larval density per bean of the former species was less than that of the latter one. There were many cases in which both C. analis and C. phaseoli emerged from one bean in large beans, but such cases were quite rare in small beans. C. analis performed interference behavior only at late larval stages, whereas C. phaseoli was superior in exploitative competition all through their larval stages. These, combined with the niche segregation inside a bean, are throught to be the major factors of observed density‐ and frequency‐dependent competition results. Based on the above experimental results, long‐term competition results between the contest and scramble species were predicted.
Biodiversity and community structure of temperate butterfly species within a gradient of human disturbance: An analysis based on the concept of generalist vs. Specialist strategies
Authors: Kitahara Masahiko , Fujii Koichi
Published: October 2006

We monitored nine butterfly communities with varying degrees of human disturbance by conducting a census twice a month during 1980 by the line transect method in and around Tsukuba City, central Japan. We analyzed the biodiversity and community structures using the generalist/specialist concept. The site (community) order based on decreasing human disturbance was positively correlated with butterfly species diversity (H′), species richness (the total number of species), and the number of specialist species in a community, but not with the number of generalist species. The number of generalist species was rather constant, irrespective of the degree of human disturbance. Thus, both the butterfly species diversity and species richness were more dependent on the specialists than the generalists. Our analyses also showed that the generalist species were distributed widely over the communities, and they maintained high population densities, resulting in high rank status in abundance in a community, with more spatial variation in density per species. Specialist species showed the opposite trends. These results demonstrate that the generalist/specialist concept is a powerful tool applicable to analyse the biodiversity and structure of natural communities.
Impact factors of purse seine net and dip net fisheries on a chub mackerel population
Authors: Matsuda Hiroyuki , Mitani Isamu , Asano Kenji
Published: October 2006

There are two major kinds of fisheries for the chub mackerel in Japan. The purse seine net fishery exploits young and adult fish during the foraging season, while the dip net fishery exploits fish before and during the spawning season. To compare the damage to the chub mackerel stock caused by purse seine net and dip net fisheries, we introduced impact factors of the two kinds of fisheries on the two kinds of fisheries and estimated number of eggs spawned in 1982. We defined the impact factor as the ratio of the average reproductive value of individuals caught by each fishery to the reproductive value at maturity. The number of individuals caught by the purse seine net fishery was 66 times larger than the number caught by the dip net fishery, while the impact factor of the former was 84% of that of the latter. Thus, the total damage caused by the purse seine net fishery was much higher than the damage caused by the dip net fishery. We can evaluate the damage caused by mortality factors on endangered species using this method.
Lattice population dynamics for plants with dispersing seeds and Vegetative propagation
Authors: Harada Yuko , Iwasa Yoh
Published: October 2006

The population dynamics of plants in a lattice structured habitat are studied theoretically. Plants are assumed to propagate both by producing seeds that scatter over the population and by vegetative reproduction by extending runners, rhizomes, or roots, to neighboring vacant sites. In addtion, the seed production rate may be dependent on the local density in the neighborhood, indicating beneficial or harmful crowding effects. Two sets of population dynamical equation(s) are derived: one based on mean‐field approximation and the other based on pair approximation (tracing both global and local densities simultaneously). We examine the accuracy of these approximate dynamics by comparing them with direct computer simulation of the stochastic lattice model. Pair approximation is much more accurate than mean‐field approximation. Mean‐field approximation overestimates the parameter range for persistence if crowding effects on seed production are harmful or weakly beneficial, but underestimates it if crowding effects are highly beneficial. Dynamics may show bistability (both population persistence and extinction) if the effect of crowding is strongly beneficial. If there is a linear trade‐off between seed production and vegetative reproduction, the equilibrium abundance of the population may be maximised by a mixture of seed production and vegetative reproduction, rather than by pure seed production or by pure vegetative reproduction. This result is correctly predicted by pair approximation but not by mean‐field approximation.
Effects of capacity on resource input and the aquatic metazoan community structure in phytotelmata
Authors: Sota Teiji
Published: October 2006

Aquatic metazoan communities in treeholes and bamboo stumps were studied on Tsushima Island, Japan, in March and June in relation to the habitat size and the resouce amount. The amount of leaf detritus increased with an increase in the capacity (volume) of the phytotelma. The input rate of leaves depended upon the opening area of the phytotelma. Twenty‐one metazoan inhabitant taxa consisted of 17 dipteran saprophages, a helodid beetle larva, a nematoda, a naidid, and a predator,Toxorhynchites towadensismosquito larva. Treeholes harbored 17 taxa and bamboo stumps 20; 16 taxa were common in both phytotelmata. The number of taxa and the biomass of metazoa per phytotelma was positively correlated with the capacity. The densities of dominant saprophages such as helodid, chironomid, andCulicoideslarvae were positively correlated with the capacity of phytotelmata, and the variation in their abundance contributed much to the variation in the species composition in individual phytotelmata. With an increase in capacity, treeholes harbored more helodids andCulicoides, whereas bamboo stumps harbored more chironomids andDasyhelea. Thus, the amount of resource, species richness and biomass per phytotelma largely depended upon the capacity, and the difference in community structure between treeholes and bamboo stumps was attributable to the differential colonization patterns of different taxa.
The learning abilities of the white cabbage butterfly, Pieris rapae, foraging for flowers
Authors: Kandori Ikuo , Ohsaki Naota
Published: October 2006

This study examines the role of learning and memory in the butterfly Pieris rapae crucivora Boisduval during foraging for flowers. In an outdoor cage with 6 flower species, P. rapae showed various visiting patterns: some visited only one species, while others visited several species in a day. The foraging process for flowers of Erigeron annuus (L.) Pers. could be divided into two successive steps: (1) landing on the nectaring caputs, and (2) finding the source of nectar in the caput. Butterflies learned to proceed through the two steps more efficiently with successive attempts: they gradually decreased landings on nectarless caputs and probings on the nectarless petals of ligulate flowers respectively. As a result, handling time per unit caputs became shorter, and apparent rewards per unit time, i.e. the efficiency of collecting nectar, increased. In addition, once learned, P. rapae could remember a rewarding flower color for 3 days, which was not interfered with by learning another flower color. This indicates that P. rapae keeps memory for a period longer than 3 days, and that they can remember at least two flower species as suitable flower resources. Furthermore, data indicated that they sometimes can apply the foraging skills obtained on other flower species to a novel one. These abilities could enable butterflies to easily switch flower species, or to enhance labile preference. It has been known that P. rapae also shows flower constancy, which may be due to memory constraints. Therefore, they may appropriately use two foraging tactics: visit consistency and labile preference, to get enough nectar according to their circumstances.
Flower nectar of an autogamous perennialRorippa indicaas an indirect defense mechanism against herbivorous insects
Authors: Yano Shuichi
Published: October 2006

This report shows that one of the most important roles of the flower nectar of an autogamous perennialRorippa indica(L.) Hieron is as an attractant for employing some ant species as a defense against herbivorous insects. The plant has flowers from spring to early winter. Its flower nectar is frequently stolen by some ant species (hereafter cited as ants) which also feed on small herbivorous insects on the plant. Internations among the tritrophic levels (R. indica, herbivores, ants) were experimentally examined and the followings became clear. (1) Ants were attracted toR. indicain search of its flower nectar. (2) The gradual secretion of flower nectar seemed to detain ants on the plant. (3)Pierisbutterfly lavae were the major herbivores onR. indicaand were potentially harmful to the plant. (4) The presence of ants reduced the survival rate ofP. rapaelarvae onR. indica. (5) The presence of ants reduced the feeding damage toR. indica. (6) The disadvantage of nectar use by ants seemed to be minimal for the plant since the ants did not disturb the other flower visitors. These facts suggest a mutualistic relationship betweenR. indicaand ants. That is, the flower nectar serves as an indirect defense against herbivorous insects.
Implications of changes in arthropod distribution following chemical application
Authors: Trumble John T.
Published: October 2006

The influence of pesticide application on the within‐field distribution of arthropods was investigated for Tetranychus urticae, the twospotted spider mite, on strawberries. Analyses of dispersions based onGreen's coefficient,Iwao's regression of mean crowding on the mean, andTaylor's power law all indicated that mite populations were highly aggregated initially. As densities increased, more of the avialable niches were filled, leading to a less clumped dispersion. However, pesticide applications causing greater than 99.9% mortality acted in a nearly density independant fashion and, although the originating populations were similar in number, did not produce dispersions equivalent to the initial migrants. As a result, ignoring these changes by developing sampling plans based on dispersion indices which generated a single slope for an entire data set, led to statistical errors that invalidated the sampling programs. In order to accurately reflect the field biology of the spidermites, sampling plans for pre and post‐treatment populations were substantially different.

The impact of such changes in dispersion were graphically demonstrated using both sequential and binomial sampling techniques. Both methods showed that fewer samples were necessary to estimate densities at a given precision level for post‐treatment populations. Also, these techniques indicated that post‐treatment populations had similar, but significantly different, dispersions. The implications of changes in pre and post‐treatment dispersions, as well as problems associated with inconsistant dispersions following pesticide use, are discussed.
Population dynamics of a phytophagous lady‐beetle, Henosepilachna vigintioctopunctata (Fabricius), living in spatio‐temporally heterogeneous habitats. I. Estimation of adult population parameters based on a capture‐recapture census
Authors: Hirano Kohji
Published: October 2006

The population processes of the lady‐beetle, Henosepilachna vigintioctopunctata (F.), were studied from the spring of 1976 to 1979 in an area (about 150,000 m2) including 17 patches of host plants.

Amplitudes of yearly fluctuations of adult densities were 2.9 for overwintered adults, and 1.4 and 1.9 for the first and the second generation adults, respectively.

The higher the adult density, the lower the rate of increase of the number of adult females to the next generation. However, the density dependent decrease in the reproductive rate was not caused by starvation.

The patchy nature of the farmland habitats seemed to have effects on the stabilization of population numbers.
Metastability of forest ecosystems infested by bark beetles
Authors: Berryman Alan A. , Stenseth Nils Chr , Wollkind David J.
Published: October 2006

A simple two‐species differential equation model is used to investigate the intrinsic metastability of forest ecosystems subjected to bark beetle infestations. We demonstrate that only one globally stable node or limit cycle is likely under biologically plausible conditions, but that, in the former case, this equilibrium is very sensitive to external perturbation.
Mining pattern of the honeysuckle leaf‐miner Phytomyza lonicerae
Authors: Katô Makoto
Published: October 2006

The mining pattern of the honeysuckle leaf‐miner Phytomyza lonicerae which feeds on Lonicera gracilipes was analyzed with special reference to the avoidance of parasitoids' attacks. The leaf‐miner makes the linear mine with branches and crosses by turning and branching, off the backtracking mine. Both average numbers of turnings and branchings were about 4. The speed of mining was 1.5 times faster in backtracking than in advancing. The mine width increased as the mining larva grew and total volume of consumed plant tissue was nearly constant independent of variability of the number of turnings and other characteristics of the mine. The majority of larval mortality were due to attacks by parasitoid wasps (Chrysochairs pentheus and Diglyphus minoeus), which locate the present position of leaf‐miners, by tracing mine tracks, and wasps attack leaf‐miners at a higher rate in backtracking than in advancing. The adaptive significance of branching and crossing by leaf‐miners was discussed in terms of the reduction of parasitoids' attacks.
Life cycle of a non‐diapausing population of the two‐spotted spider mite, Tetranychus urticae Koch in a pear orchard
Authors: Takafuji Akio , Kamibayashi Mitsuji
Published: October 2006

The life cycle of a non‐diapausing T. urticae population was studied in a pear orchard in the southern part of Okayama Prefecture, western Honshû, Japan. The mites overwintered only on biennial weeds in the orchard without entering diapause, started to increase in number in early spring on them and then moved to other weeds as they emerged. The occurrence of the mites on pear began in early May several weeks after the unfolding of pear leaves and the population on pear was initiated by the migrants from the weeds around the base of pear trees. The population on pear showed two distinct peak occurrences, one in June and the other in mid‐autumn. After pear leaves dropped in late autumn, the mites returned to biennial weeds for overwintering.
Evaluation of the role of Microvelia douglasi atrolineata (Bergroth) (Heteroptera: Veliidae) as predator of the brown planthopper Nilaparvata lugens (Stål) (Homoptera: Delphacidae)
Authors: Nakasuji Fusao , Dyck V. A.
Published: October 2006

The biology of the veliid bug M. d. atrolineata, its predatory behavior, and the effects of plural hunting were studied to evaluate its role as a predator of the brown planthopper Nilaparvata lugens in the Philippines. The probability of planthoppers falling onto the water surface and provision of habitat continuity was measured by a sticky trap placed at the base of rice hills in a greenhouse and in paddy fields.

The developmental period of immature stages combined was 21 days. If given prey, females laid 25 eggs on the average during an adult life span of 18 days. Starved adults could survive for only 3–5 days.

The functional response to prey density was sigmoid, and the maximum number of prey killed was 7 per day. Prey feeding was completed in 12–36 min. The percentage of successful prey attacks averaged 5–8%, decreasing with higher (and larger) developmental. stages of prey, but adult prey were found the soonest. Plural hunting increased the probability of capturing prey by as much as 2.5 times that by individual hunting.

Late‐instar nymphs, which may be more active, fell from rice hills in a greenhouse more than early‐instar nymphs, and the number falling increased with density. In the field the percentage of planthoppers falling to the water in 1 day varied considerably, from 1% for nymphs in one field to 67% for adults in another field.

On the basis of work described above and given the high density of veliid predators in flooded paddy fields of tropical Asia, M. d. atrolineata is considered one of the most important natural enemies of the brown planthopper.
Component analysis and modelling of the movement process: Analysis of simple tracks
Authors: Kitching R. L. , Zalucki M. P.
Published: October 2006

The construction of a general model of animal movement using the ‘experimental components' approach ofC. S. Holling is proposed. The process of ‘movement’ is interpreted very generally as any displacement of the whole organism in space. The rationale for modelling such processes rests upon the idea that there is a basic “canonical” pattern of movement characteristic of a species moving in a homogeneous environment, which pattern is overlaid by the various directional stimuli present in more usual heterogeneous environments.

The ‘canonical movement model’ is a necessary first step in construction of more realistic representations. We suggest it can be made using six components viz. the initial heading of the animal, the mean and variance of the angular displacements made by the animal as it moves, the mean and variance of the speed of the animal, and a term for the continuity of the movement. We have measured all these components in the field for the two‐dimensional movement of the inter‐tidal snail, Polinices incei and these results are presented here. Difficulties inherent in the measure ment of angular displacement in particular are discussed and means of resolving them proposed.

The shortcomings involved in the measurements and techniques for their more detailed representation and the next steps in the proposed modelling sequence are discussed.
Pest population stability under sterile releases
Authors: Barclay Hugh J.
Published: October 2006

The stability of a pest population is one of the critical features to be examined when considering a control strategy for a given pest species. Four models involviing sterile male releases are examined for various stability characteristics; the models examined were: (i) a simple one stage model with no species interactions, (ii) a two life‐stage model, (iii) a model involving two competing species, (iv) a model in which the pest is under predation. Of the four, the simple model was the most stable and the predation model was the least stable under continued sterile releases.
Evolution of litter size
Authors: Itô Yosiaki , Iwasa Yoh
Published: October 2006

Theories on the evolution of litter size among organisms were reexamined. The competition theories, including that based on the r−K‐selection hypothesis, could not explain well why low‐fecundity strategies have often evolved in stressful environments such as mountain streams, deep sea and the antarctic, where interspecies competition is considered to be lax. The theory, based on Itô's (1980) concept of the procurability of food by the young, was considered to have greater generality because it could explain not only the above‐mentioned cases but also those where small litter size is observed in habitats with high species diversity (where interspecific competition may be keen), such as tropical rain forest. Examination of the process of selection of high‐fecundity and low‐fecundity genotypes also suggested that the procurability of food by the young can best explain the evolution of low‐fecundity. The concept of density‐induced dispersal and a distinction between density‐dependent and density‐independent predation pressures should be incorporated into our discussions on the evolution of reproductive rates.
Contest and scramble competitions in Callosobruchus maculatus (Coleoptera: Bruchidae) II. Larval competition and interference mechanisms
Authors: Toquenaga Yukihiko
Published: October 2006

Competition between contest and scramble strategists was examined using two strains of Callosobruchus maculatus, the contest strain (iQ) and the scramble strain (tQ). The direct larval interference experiment within each strain showed that the contest strain performed strong direct interference throughout its larval stage against the conspecific opponent(s). The scramble strain also performed its interference, but only during the 3rd and the 4th larval stages. The inter‐strain larval competition experiments inside a large and small mung bean (Vigna radiata) showed that the contest strain was, in general, superior to the scramble strain in competition, but the competition results were density‐ and frequency‐dependent. In the large beans, the proportion of adult emergence of the contest strain increased with the increase of its own initial density but decreased as the initial density of the scramble strain increased. The shape of the proportion of adult emergence became nonlinear in the small beans. The cause of the complexity of inter‐strain competition results was discussed in the light of the difference in larval interference ability between the two strains.
Altered levels of PP2A regulatory B/PR55 isoforms indicate role in neuronal differentiation
Authors: Schild Andreas , Schmidt Karsten , Lim Yun‐An , Ke Yazi , Ittner Lars M. , Hemmings Brian A. , Götz Jürgen
Published: October 2006

The ubiquitously expressed serine/threonine‐specific protein phosphatase 2A (PP2A) is prominent in brain where it serves a wide range of functions under both physiological and pathological conditions. PP2A holoenzymes are composed of a catalytic subunit and a tightly complexed scaffolding subunit. This core enzyme associates with regulatory subunits of the B/PR55, B′/PR56/PR61, B″/PR72 and B‴/PR93/PR110 families. We previously determined distribution and expression levels of the four members of the B/PR55 family in brain, as dysregulation of this subunit family has been specifically implicated in neurodegenerative disorders including Alzheimer's disease. In the present study, we used cell lines widely used in neuroscience research to determine levels of the four PR55 isoforms by qRT‐PCR under different experimental conditions. We show that PR55α mRNA levels are highest in both HEK293 cells and SH‐SY5Y neuroblastoma cells whereas PR55β levels are lowest. Stepwise neuronal differentiation of SH‐SY5Y cells causes the selective upregulation of PR55β, and to some extent PR55γ and PR55δ, but not PR55α mRNAs. In agreement with the qRT‐PCR analysis, neuronal differentiation does not alter PR55α protein levels, whereas interestingly, PR55β and PR55γ protein levels are reduced when compared to undifferentiated cells. Our data point at specific roles for distinct regulatory B/PR55 subunits of PP2A in neuron‐like cells with PR55α being the major isoform.
Challenges to demonstrating disease‐modifying effects in Alzheimer's disease clinical trials
Authors: Cummings Jeffrey L.
Published: October 2006

Progress in understanding the molecular biology of Alzheimer's disease (AD) has provided a number of plausible therapeutic targets for disease‐modifying interventions. To advance these agents toward eventual US Food and Drug Administration (FDA) approval and incorporation into clinical practice by physicians and acceptance by patients and caregivers it is necessary to reach consensus on the meaning of disease modification and on what information is needed to provide a compelling factual basis for distinguishing disease modification from symptomatic treatment effects. Disease modification requires that the intervention have an impact of underlying pathology and pathophysiology of AD; disease course modification, illness modification or disability sparing are alternate terminologies that could be applied to symptomatic agents that do not affect the underlying neurobiology of AD. A variety of trial designs have been proposed to provide information supporting disease modification including change from baseline designs, survival type designs, staggered start designs, and staggered withdrawal designs. Each of these has shortcomings, and by themselves trial designs are not likely to provide sufficient information to conclusively prove that disease modification has occurred. Incorporation of a biomarker into clinical trials will support the claim for disease modification. Such a surrogate marker ideally should respond to the intervention, predict the clinical response to the intervention, and be compellingly related to the neurobiology of AD in the pathway affected by the intervention. A third axis of information supportive of disease modification is derived from observation of the effect of treatment in animal models of AD. The triad of a clinical outcome consistent with disease modification, support from a surrogate marker incorporated into the clinical trial, and basic science information indicating the effect of the therapy on a model of AD would combine to make a convincing case for disease modification.
Cytoskeletal modulators and pleiotropic strategies for Alzheimer drug discovery
Authors: Schenk Dale , Carrillo Maria C. , Trojanowski John Q.
Published: October 2006

The Alzheimer's Association Research Roundtable, a consortium of Association senior scientists and leaders from pharmaceutical, biotech, and imaging companies, met to discuss strategies for developing novel therapeutics for the treatment of Alzheimer's disease (AD). The goal of the meeting was to address, primarily, strategies that do not hinge on directly modulating levels of β‐amyloid. The identification of β‐amyloid as the major constituent of senile plaques and the subsequent discovery that familial AD can be caused by mutations in either the β‐amyloid precursor protein or presenilins, proteases that cleaves β‐amyloid from its precursor, has spawned numerous therapeutic strategies for treating AD. These include passive and active vaccines for clearing β‐amyloid from the brain and the development of small molecule inhibitors of β‐ and γ‐secretases that can attenuate the production of β‐amyloid. But the field recognizes that there is more to AD than β‐amyloid alone. What role do neurofibrillary tangles play in the disease, for example, and how are they influenced by β‐amyloid? What lies upstream of β‐amyloid production in the sporadic AD brain, and how do apolipoproteins and cholesterol influence disease progression? Are there environmental or behavioral factors that contribute to the initiation or progression of sporadic AD? Because of the complexity of AD, the field is continually looking to other therapeutic strategies that may complement or substitute for therapies that target β‐amyloid. This roundtable meeting was charged with discussing and evaluating some of those strategies.
Volar Lunate Dislocation Associated With A Salter-Harris Type III Fracture of the Distal Radial Epiphysis in an 8 Year-Old Child
Authors: SHARMA H. , AZZOPARDI T. , SIBINSKI M. , WILSON N.
Published: October 2006

Carpal fracture-dislocations in children are extremely rare injuries and are easily missed or misdiagnosed. An 8 year-old boy who presented with a volar lunate dislocation associated with a Salter Harris Type III injury of the distal radial epiphysis is reported. Open reduction without internal fixation followed by plaster immobilisation achieved good short-term results.