bluuebunny/crossref_metadata_2025 huggingface dataset:
Niche modification and stability of competitive systems. III. Simulation model analysis
Authors: Shimada Masakazu , Fujii Koichi
Published: October 2006

Simulation model for niche shift in ecological time scale was constructed on the basis of the optimal foraging theory. In accordance with the previous experimental study (Shimada andFujii, 1985), the model competitive system consisted of 2 parasitoid wasp species utilizing 4 host stages. Wasps were assumed to choose host stages in the manner that they realized the maximal gain/cost values, where gain was represented by body weight of a wasp progeny emerging from each host stage and cost was expressed by time required to search for and detect an unparasitized host. The number of parasitized hosts in each host stage was calculated numerically by usingArditt's (1983) model for avoidance of superparasitism.

The model simulated well the experimental results ofShimada andFujii (1985) andShimada (1985). Sensitivity analysis of the model showed that the experimentally derived criterion for competitive coexistence (different second‐best host stages between competing species even with the common best) was not necessarily the indispensable condition for niche shift and separation, but that if the criterion was not satisfied, stable competitive coexistence occurred only in the narrow range of the parametric values. Further, niche shift in ecological time scale made the competitive coexistence more stable than fixed niche on which the current niche theory stands.
Adult population parameters and life tables of an epilachnine beetle (Coleoptera: Coccinellidae) feeding on bitter cucumber in Sumatra
Authors: Abbas Idrus , Nakamura Koji
Published: October 2006

The population dynamics of an epilachnine beetle, which is closely related toEpilachna sparsaDieke(henceforth called “sp. C”) and feeds on bitter cucumberMomordica charantia, was studied by mark‐recapture of adults and the construction of life tables. The study was repeated three times, i.e., March–May, July–September and October–December in 1982, in Padang, Sumatra, Indonesia. After the establishment of the host plants, adults of “sp. C” soon colonized, and each study period ended in the death of the plants due to defoliation by the larvae and adults. The estimated mean length of residence of adults ranged from 6–11 days, but this was probably much shorter than the actual longevity, because the adults were so active that they flew away, or dropped off the plants, when they were approached or slightly disturbed. Life tables indicated that egg mortality ranged from 17.8–53.9%, and a parasitic waspTetrastichussp. B made up 41.1–64.2% of egg mortality. Two wasps,Tetrastichussp. C andPediobius foveolatuskilled 1.2–19.4% (7.6–100%)*of 4th instars and only the latter species attacked the pupae, killing 24.6–59.1% (45.1–72.4%). Parasitism and starvation by overcrowding contributed most to the total mortality from egg to adult emergence, which ranged from 89.4–99.5%. “Sp. C” had a higher diversity and level of parasitism than the Japanese species,E. vigintioctopunctata. The high dispersal power of “sp. C”, coupled with the prolongedlx−mxschedules shown under laboratory conditions, was advantageous for exploiting the food plant which was available throughout the year, but was rather patchily distributed in space.
Colony development and social structure in a subtropical paper wasp, Ropalidia fasciata (F.) (Hymenoptera: Vespidae)
Authors: Itô Yosiaki
Published: October 2006

More than 50% of nests of Ropalidia fasciata were founded by association of foundresses (multifemale nests). The multifemale nests were generally initiated earlier and grew faster than the single‐female nests. The survival rate of the multifemale nests was significantly higher than that of single‐female nests, and the productivity as measured by the number of cells produced per foundress had a peak at a foundress‐group size from 6 to 10. The number of marked foundresses which were seen on their original nest decreased as the colony cycle proceeded, but some of them continued to coexist on the original nests after emergency of many female progeny. Except in the case where a large number of foundresses attended a young nest so that some foundresses could not sit on the nest, the dominance interactions among cofoundresses were mild. More than twothirds (71.4%) of nests (including those at the post‐emergence stage) had multiple egg‐layers. The foundress association in this species is considered to be beneficial for every foundress because it raises ability to avoid predation or to reconstruct their nests when the nests are destroyed by typhoons.
Limitation of reproduction by feeding condition in a carabid beetle, Carabus yaconinus
Authors: Sota Teiji
Published: October 2006

Effects of the amount of food consumed on reproduction of the carabid beetle, Carabus yaconinus B., were studied in the laboratory by rearing beetles at different food levels, and the feeding and oviposition rates in the field were estimated on the basis of the relationships between the amount of food consumed, body weight and egg production obtained in the experiment.

The maximum amount of food consumed was 150 mg of minced beef per day. The number of eggs laid per day and the mean body weight increased with an increase in the amount of food consumed. High mortality occurred only when the beetles consumed less than 25 mg of minced beef per day.

The ratio of current body weight to the minimum one just before death by starvation, W/Wmin, was used for the estimation of the rates of food consumption and egg production. The relationships between mean W/Wmin ratio, the amount of food consumed and the number of eggs laid per day were clarified.

The relationships between ovary states (ovary weight and the number of mature eggs in the ovary) and W/Wmin ratio were examined for the females caught in the field. Females with higher values of W/Wmin ratio had more mature eggs.

The amount of food consumed by females in the field during the reproductive period was estimated to be 50–70% of the maximum value attained in the experiment and the estimated rate of oviposition was 45–59% of the maximum rate attained in the experiment.
Oviposition site selection and avoidance of additional mating by females of the dragonfly, Cordulia aenea amurensis Selys (Corduliidae)
Authors: Ubukata Hidenori
Published: October 2006

Females of an odonate species in which oviposition sites overlap with mating sites may adopt one or more of the following strategies when they lay eggs except when they ‘trade’ mating for access to suitable oviposition sites or for services (guarding, etc.) provided by males: (1) ovipositing at hidden places; (2) ovipositing at a time when males are neither patrolling nor watching; (3) indicating non‐receptivity by a behavioral display. The density of ovipositing females of the dragonfly, Cordulia aenea amurensisSelys which was studied between 1970 and 1983 at a pond (Hôrai‐numa, Sapporo, Hokkaido) had a high negative correlation with the distance from ‘entrance’ (a part of shore at which the arrival of most adults seems to have occurred). On the other hand, oviposition was rarely observed at a sector being distant from entrance in spite of the inference that larval survivorship was probably high at this sector. Most females oviposited among emergent vegetation in which approach of males to them was difficult, and they scarcely traveled across the open water in search of oviposition sites. Therefore, most females of the population studied were considered to adopt the first strategy. The second and third strategy were not adopted by the population studied. Finally, the influences of some environmental factors and traits possessed by a species on the adoption of these tactics or on the execution of the ‘trades’ were discussed.
Population dynamics of houseflies, Musca domestica, on experimentally accumulated refuse
Authors: Imai Chobei
Published: October 2006

The population dynamics of the housefly, Musca domestica, on patchy and unstable habitats consisting of refuse was investigated at a waste disposal site by using sticky flypaper and mark‐release‐recapture technique (Jolly‐Seber's method). The newly disposed garbage was favorable for breeding of the flies for about one month after being disposed, while a mixture of garbage and ash from incinerated refuse was less favorable. On the garbage under favorable conditions, the rates of population increase was 1.25–2.82 per day, and approximately 1300–1500 flies were produced per square meter within the available period of one month. The rapid decrease in the fly density was observed just after the appearance of high density peaks. The mark‐release‐recapture study suggested that this rapid decrease would be mainly due to the density‐dependent emigration of adult flies from the patchy habitats. The emigration was also activated when the time after garbage disposition became long.
Population dynamics of Luehdorfia japonica Leech (Lepidoptera: Papilionidae)
Authors: Matsumoto Kazuma
Published: October 2006

An adult population of a papilionid butterfly, Luehdorfia japonicaLeech, was studied by marking, release and recapture procedures in a hilly region in the suburbs of Kanazawa City, Japan.

Age of butterflies was estimated from the wing wear conditions, rated as winage categories 0 to 6.

Jolly (1965) andSeber's (1973) method was applied to the marking‐recapture results for estimating the population parameters (sampling ratio, population size and survival rate).

Sampling ratio of males was consistently higher (around 50%) than that of females.

Newly emerged females were especially inactive, so that few of them were captured. From day 6.5 to day 10.0 they began to oviposit and became more active and more catchable.

An approximate sex ratio of 1∶1 was confirmed from the specimens collected in the field and by rearing experiments.

Daily survival rate was about 0.75–0.80 and mean longevity was about 4 days for both sexes. The maximum longevity observed was 17 days, for males and 21 days for females.

Dispersal by both sexes of the butterfly was more than 1 km.
Simulation of the interactions of predatoryTyphlodromusmites with the European red mite,Panonychus ulmi(Koch)
Authors: Johnson D. L. , Wellington W. G.
Published: October 2006

Interactions ofTyphlodromusmites and their prey, the European red mite, in orchard settings were examined through computer simulation. In particular, the consequences of very slow dispersal by the predators, compared with the weather‐dependent higher rates of prey dispersal, were elucidated. In simulations of the interactions of the predator and its prey, both dispersal and temperature strongly affected the available supply of juvenile prey, and thus could determine whether the predators on an individual tree survived or perished.
Dispersion analyses and resource utilization of aphid parasitoids in a non‐depletable environment
Authors: Trumble John T. , Oatman Earl R.
Published: October 2006

Dispersions and resource utilization of primary and secondary parasitoids developing in non‐depletable primary host populations were determined for an aphid‐parasitoid community occurring on strawberries. Analyses of dispersions based onGreen's coefficient andLloyd's Patchiness Index indicated parasitized aphids were highly aggregated initially, became less aggregated as density increased, and remained aggregated following collapse of the aphid populations. The “index of aggregation” values calculated usingTaylor's Power Law concurred with results from the other indices, and the similarity of the regression coefficients from both seasons suggests that the index of aggregation may be characteristic for communities as well as species. Analysis withIwao's regression of mean crowding on the mean generated similar results when population data were stratified temporally, and also indicated that the individual was the basic unit of the population.

In a non‐depletable environment, oviposition of individuals exhibiting an aggregated dispersion pattern within clumps of hosts provides primary parasitoids with a suitable trade‐off between energy utilization or genetic potential, and losses associated with hyperparasitism.
Postmetamorphic growth, survival, and age at first reproduction of the salamander, hynobius nebulosus tokyoensis Tago in relation to a consideration on the optimal timing of first reproduction
Authors: Kusano Tamotsu
Published: October 2006

The postmetamorphic growth and survival of the salamander Hynobius nebulosus tokyoentisTago were surveyed in the study site located in Habu village of Hinodemachi, a suburb of Tokyo City, during 1975–1981. A laboratory experiment on the growth rate of juveniles was conducted in parallel with the field survey. The result indicated that this salamander grew at the rate of 8,mm in s.v.l. per year during the juvenile stage, but its growth rate decreased markedly as low as 1.8 mm for males and 1.1 mm for females, once it had attained sexual maturity. According to the “capture‐recapture” procedure the annual survival rate after metamorphosis was found to be quite high; that is, approximately 0.7. By using the growth rate of juveniles and the difference between the sizes at metamorphosis and sexual maturity, the age at first reproduction was estimated to be 4 year for males and 5 year for females.

From the data obtained in this study, the intrinsic rates of increase (r) were calculated for various values of age at first reproduction under different survival schedules, and the relationship between the age at first reproduction and fitness as measured by r was examined. The result indicated that an optimal age maximizing fitness always existed under respective survival schedules, and the observed age at first reproduction of this salamandei was found to coincide well with the predicted optimal age.
Reproductive strategy of insects as adaptation to temporally varying environments
Authors: Tsuda Yoshio
Published: October 2006

Diversity of oviposition curve observed in 125 insects was analysed using the ratio of the length of period for development to that for reproduction. On the basis of this empirical data, two extreme reproductive patterns were selected: prolonged reproduction with early maturity and concentrated reproduction with late maturity. Population growth of the species with each reproductive pattern was calculated usingLeslie Matrix under some simulated fluctuating environments where the length of time during which the environments change is short compared with the time required to stabilize age structure. These simulation studies show that there is an optimal ratio of the length of period for development to that for reproduction in achieving high population densities and this ratio varies depending on the favorableness of environment for reproductive success: as the environmental favorableness decreases, the optimal ratio becomes larger.
The regulation of activity in populations of the terrestrial slug Limax maximus (Gastropoda; Limacidae)
Authors: Rollo Christopher David
Published: October 2006

The activity of the slug Limax maximus was studied in relation to weather. Three hundred‐and‐fifty‐eight hourly observations of activity and weather were made on 21 nights from May until October, 1976. Factors causally important to molluscan activity were included in a step‐down correlation‐regression analysis of daily and seasonal behavior. The analysis was also performed using weather data from the previous hourly observation. Models using lag‐weather did not explain as much variability as did concurrent weather.

The regression models explained about 73% to 87% of the observed variation in activity. The most important factors included in the regression models were time of day (circadian rhythm), light intensity, changes in light intensity and surface temperature. Shelter temperature, temperature gradients, length of the night, and time of sunset were also included in some models. Age and hydration were shown to be key factors in other experiments.

A model incorporating weather thresholds estimated from field data explained 83.06% of the variability in the activity of L. maximus over the season. The values predicted from the model did not differ significantly from those actually observed in the field (Kolmogorov‐Smirnov test, p>0.50).
A population study of the japanese wood mouse, Apodemus speciosus (Mammalia: Muridae), with reference to its social behavior
Authors: Kondo Takaki
Published: October 2006

The role of social behavior on the population regulation of the Japanese wood mouse, Apodemus speciosus, was studied in the Ashu Experimental Forest of Kyoto University by monthly trapping and direct observation on the social behavior at the artificial feeding site. The census was carried out from May to October in 1974 and 1975, and the direct observation in June, August and October, 1975.

In the study area, the Japanese wood mouse has two breeding seasons in a year: in spring and in autumn. Minimum survival rate was high in the non‐breeding season and low in the breeding season. It was negatively correlated to the number of sexually active adults in both sexes.

Home ranges of females tended to be mutually exclusive, and female residents prevented the settlement of female immigrants. On the other hand, home ranges of males overlapped largely and males had a straight social hierarchy. Subordinate males tended to disappear more often than dominant males did, but male residents did not hinder the settlement of male immigrants. Males may regulate their number by driving out the subordinate males, while females by spacing behavior.
Different response in respiration between predaceous and phytophagous lady beetles (Coleoptera: Coccinellidae) to starvation
Authors: Tanaka Koichi , Itô Yosiaki
Published: October 2006

Survival times and changes in the respiratory rates and the live body weights of a predaceous lady beetle, Coccinella septempunctata bruckiiMulsant, and a phytophagous lady beetle, Henosepilachna vigintioctopunctataFabricius, under starved conditions were compared.

Females of C. septempunctata survived for a long time, 91.4±27.2 days, under starved conditions. On the other hand, males of C. septempunctata and males and females of H. vigintioctopunctata survived for 31.3±10.2, 17.6±6.0 and 22.9±5.3 days, respectively. These values were much shorter than that of C. septempunctata females.

The respiratory rate of starved C. septempunctata increased on the first day of starvation, but hereafter rapidly decrased till the fourth day, keeping an almost constant level thereafter. On the tenth day of starvation, the respiratory rates of C. septempunctata were 56.4% in males and 58.5% in females of initial values. The respiratory rate of males was 1.47 to 2.14 times as high as that of females, and there were significant differences between the two.

Males and females of C. septempunctata lost their body weights by 20.2% and 17.8% of initial weights, respectively, during the first ten days of starvation.

The respiratory rate of starved H. vigintioctopunctata did not significantly change till the fourth day of starvation, and thereafter decreased slowly. On the tenth day of starvation, the respiratory rates of H. vigintioctopunctata were 70.3% in males and 74.8% in females of initial values. These values were much higher than those of C. septempunctata.

Males and females of H. vigintioctopunctata lost their body weights by 22.4% and 25.4% of initial weights, respectively, during the first ten days of starvation. Thus under starvation H. vigintioctopunctata underwent the larger weight loss than C. septempunctata.

Differences in strategies against starvation between poikilothermal predators and herbivores and their roles in population dynamics were discussed.
The species‐area relation for archipelago biotas: Islands as samples from a species pool
Authors: Kobayashi Shiro
Published: October 2006

If the immigration of species from a mainland or among islands is taken into account, each island of an archipelago can be regarded as a sample from a species pool. When two or more islands are combined so as to give larger samples, the resultant species‐area relation does not differ from that observed in a continuous and homogeneous habitat on a mainland. This relation can be described by either of the two mathematical models proposed before (Kobayashi, 1975, 1976). A power function seems to be insufficient because the discrepancy between the observed and the calculated values becomes larger with the increasing area. In a log‐log plot, the slope values for these alternatives to a power function vary continuously from 1 to 0 as the area increases. Owing to the spatially clumped distribution of each species, the number of species found on a single island is less than that found on several smaller islands of equivalent total area. Hence the species‐area relation for individual islands has a smaller slope value than that obtained by combining the different numbers of islands and approaches a power function in form. From these results, it is concluded that the species‐area data on archipelago biotas are equivalent to the case where separate samples of different sizes are drawn from a universe in which each species is spatially distributed in clumps. The properties of archipelago biotas which have so far been evidenced or predicted are consistent with this conclusion.
Studies on the distribution pattern of the pine needle gall midge, Thecodiplosis japonensisUchida etInouye (Diptera: Cecidomyiidae) in a pine forest
Authors: Soné Koichi , Takeda Hiroshi
Published: October 2006

Numerical changes and distribution patterns of the pine needle gall midge, Thecodiplosis japonensisUchida etInouye, were studied during the period from 1978 to 1979 in a young plantation of Pinus thunbergii in Shiga Prefecture, Japan. The survivorship curve of this species was characterized by a low mortality of larvae in galls and two high mortalities before the formation of galls and during the overwintering period in soil.

The within and between‐trees distributions of eggs and larvae in galls were examined by using the regression method. The egg distribution per shoot was aggregative both within and between host plants. The within‐tree variations in numbers of eggs per shoot were related to the differences in the abundance of available needles for oviposition per shoot among the canopy layers. The between‐tree variations reflected the heterogeneous emergence of adult females in the study plot. The degree of aggregation increased from egg to gall stage in both within‐ and between‐tree distributions and the increase was explained by the different mortality of larvae within trees and the inversely density‐dependent mortality between trees.

The distribution patterns in the soil habitat stages were examined by the patchness index (). This species showed aggregative distributions in soil stages. There was a correlation in spatial patterns of adult emergence between the successive generations.

The distribution properties of this species were discussed in connection with the population dynamics and the availability of host plants in the study plot.
Simulation of movement and egglaying in Danaus plexippus (Lepidoptera: Nymphalidae)
Authors: Zalucki Myron P.
Published: October 2006

A model simulating the movement and oviposition of monarch butterflies over a female's life time is presented. The model's predictions compare favourably with observed data and suggest that females who lay eggs in an optimal fashion should have low directionalities in areas with high host plant density (patches and single plants) and high directionalities in areas with low host plant density. The model also provides one means of combining individual animal processes and spatial heterogeneity into population dynamics.
How three rocky shore snails coexist on a limited food resource
Authors: Spight Tom M.
Published: October 2006

Competition theory poses a major problem when several species coexist on what appears to be one resource. Three Thais species living on the Pacific Northwest Coast provide an example: at many sites, all three depend primarily on one barnacle species. Growth rates of three species were measured for 3 years and these provide an indirect means to assess how these snails use their common food resource. Major temporal differences were observed:T. lamellosa grew 0–1 mm/mo during the spring and 2–3 mm/mo during the summer, while T. emarginata and T. canaliculata grew 2–3 mm/mo during the spring and 0–1 mm/mo during the summer. However, all species are opportunists when food is available, and seasonal and interspecific differences disappeared when all three species were kept well fed together in the laboratory. Therefore, temporal differences arise from spatial segregation rather than from intrinsic differences in activity, and must arise because barnacle abundance patterns differe consistently from one area of the shore to another. Species‐specific activity patterns lead each species to a food intake that is independent of the food supply on the shore as a whole and is also independent of food intake by the other two species. Where two snail species depend upon a single food species, their use of the food supply appears to make it function as two different resources. This resource use is possible because prey quality is markedly dependent on shore level.
Comparative studies on the seasonal occurrence, nymphal development and food menu in two giant water bugs, Diplonychus japonicus vuillefroy and Diplonychus major esaki (Hemiptera: Belostomatidae)
Authors: Okada Hiroaki , Nakasuji Fusao
Published: October 2006

We compared the seasonal changes in population density and nymphal development at different water temperatures and under different food conditions between two giant water bugs, Diplonychus japonicus and D. major, in Okayama, Japan.

D. japonicus produced 1–2 generations a year, while D. major was strictly inivoltine. The developmental velocity was higher in D. japonicus than in D. major. The thermal constant of D. japonicus was less than that of D. major. These results suggest that D. japonicus is adapted, to higher water temperature than D. major. In the field, D. japonicus preyed predominately on Lymnaeidae and Physidae snails, while D. major preyed on aquatic insects such as dragonfly nymphs.
Pollination of strawberry by the stingless bee, Trigona minangkabau, and the honey bee, Apis mellifera: An experimental study of fertilization efficiency
Authors: Kakutani Takehiko , Inoue Tamiji , Tezuka Toshiyuki , Maeta Yasuo
Published: October 2006

To know basic information about the stingless bee, Trigona minangkabau, and the European honey bee, Apis mellifera, as pollinator of strawberry, we set three greenhouse areas: the honey bee introduced area, the stingless bee introduced area and the control area. Foraging and pollination efficiencies of the two bee species were studied comparatively.

During the experimental period (10 days), the stingless bee foraged well and the nest weight did not change, though the honey bee often foraged inefficiently and the nest weight decreased by 2 kg. The average nectar volume of a flower was lower in the honey bee area (0.02 μl) and nearly the same in the other two areas (0.1 μl).

We make a numerical model to describe pollination and fertilization process. This model shows that one visit of the honey bee pollinated 11% of achenes and one visit of the stingless bee did 4.7% on average and that 11 visits of the honey bee or 30 visits of the stingless bee are required per flower to attain normal berry (fertilization rate, 87%). In this study, the rate of deformed berries in the stingless bee area (73%) was lower than that of the control area (90%), but higher than that of the honey bee area (51%). From our numerical model, we conclude the stingless bee could pollinate strawberry as well as the honey bee if we introduced 1.8 times of bees used in this experiment.
Factors associated with use of medications with potential to impair cognition or cholinesterase inhibitors among Alzheimer's disease patients
Authors: Huey Edward D. , Taylor Joy L. , Luu Pauline , Oehlert John , Tinklenberg Jared R.
Published: October 2006

Background

The aim of this study was to use a signal detection method to examine the prevalence of, and patient characteristics associated with, medication with potential to impair cognition and cholinesterase inhibitor use in patients with Alzheimer's disease.

Methods

A cross‐sectional study was conducted of 1,954 patients with a diagnosis of probable or possible Alzheimer's disease. Concurrent medications were measured, specifically: (1) a medication with potential to impair cognition or (2) a cholinesterase inhibitor. Predictor variables included age, gender, ethnic group, education, age of symptom onset, number of prescriptions, number of medical diagnoses, Mini‐Mental State Examination (MMSE), Blessed‐Roth Dementia Rating Scale (BRDRS), probable versus possible AD diagnosis.

Results

Fifteen percent of the Alzheimer's disease patients were on a medication with potential to impair cognition, and 44% were on a cholinesterase inhibitor. Patient characteristics associated with the prescription of a medication with potential to impair cognition included total number of prescription medications, low education, low MMSE, older age, reported lack of vitamin use, and more medical diagnoses. Patient characteristics associated with the prescription of a cholinesterase inhibitor included reported use of vitamins, the total number of prescription medications, fewer medical diagnoses, lower age of symptom onset, and higher education.

Conclusions

Determining the patient characteristics associated with the prescription of a medication with potential to impair cognition can help clinicians identify patients who are at risk for drug‐related morbidity. Patient characteristics unassociated with dementia appear to influence the prescription of cholinesterase inhibitors. Signal detection analysis is well suited to this type of research.
Joint ventures around the globe from 1990–2000: Forms, types, industries, countries and ownership patterns
Authors: Moskalev Sviatoslav A. , Swensen R. Bruce
Published: October 2006

Joint ventures (JVs) and alliances are important forms of inter‐organizational cooperation because they allow firms to achieve complex mutual tasks, otherwise impossible using simple arm's‐length contracts, but without actually acquiring one another. In light of recent trends in globalization, this feature of JVs and alliances is vital to multi‐national corporations (MNCs). These firms have complex operations, making simple arm's‐length contracts insufficient. MNCs are also very large, so that mergers and acquisitions and takeovers are extremely expensive. In this paper, we describe global trends in JVs and alliances for the period 1990 to 2000, utilizing the Thomson Financial SDC Platinum database. We survey the relevant literature on JVs and alliances, and provide a detailed description of the world of JVs and alliances as depicted by this database. We report a number of interesting facts regarding the forms and types of JVs and alliances, their industry and geographic distribution, and patterns of ownership.
Sex differences in brain activation patterns during processing of positively and negatively valenced emotional words
Authors: HOFER ALEX , SIEDENTOPF CHRISTIAN M. , ISCHEBECK ANJA , RETTENBACHER MARIA A. , VERIUS MICHAEL , FELBER STEPHAN , WOLFGANG FLEISCHHACKER W.
Published: October 2006

Background. Previous studies have suggested that men and women process emotional stimuli differently. In this study, we used event-related functional magnetic resonance imaging (fMRI) to investigate gender differences in regional cerebral activity during the perception of positive or negative emotions.

Method. The experiment comprised two emotional conditions (positively/negatively valenced words) during which fMRI data were acquired.

Results. Thirty-eight healthy volunteers (19 males, 19 females) were investigated. A direct comparison of brain activation between men and women revealed differential activation in the right putamen, the right superior temporal gyrus, and the left supramarginal gyrus during processing of positively valenced words versus non-words for women versus men. By contrast, during processing of negatively valenced words versus non-words, relatively greater activation was seen in the left perirhinal cortex and hippocampus for women versus men, and in the right supramarginal gyrus for men versus women.

Conclusions. Our findings suggest gender-related neural responses to emotional stimuli and could contribute to the understanding of mechanisms underlying the gender disparity of neuropsychiatric diseases such as mood disorders.
WatSen: searching for clues for water (and life) on Mars
Authors: Grady Monica M.
Published: October 2006

There is plenty of evidence for fluid on Mars: large-scale (planet-wide) features have been captured over four decades by a procession of orbiting satellites equipped with cameras with increasingly higher spatial resolutions. Imagery of the surface shows channels, valleys, ice-caps, etc. Small-scale, more local evidence for fluid has come from images obtained by rovers on the Martian surface. Images that water produced many of the features are supported by spectroscopic measurements (again both planet-wide and local) over a range of wavelengths, which show the presence of minerals generally only produced in the presence of water (haemetite, jarosite, etc.). Results from meteorites continue this picture of fluid activity taking place over significant periods of Mars' history. Despite all these indicators of water, direct detection of water has never been performed. We have reviewed the evidence for water on Mars' surface, and have described WatSen, a combined humidity sensor and infrared IR detector, which can be employed to search for water at and below Mars' surface. WatSen is designed to be part of the suite of instruments on the mole that will be deployed as part of the Geophysics and Environment Package on ExoMars. The objectives of the package are as follows: (i) to detect water within Martian soil by measuring humidity and IR spectral characteristics of the substrate at surface and at depth; (ii) to determine the mineralogy and mineral chemistry of surface soils (this measurement will provide the mineralogical context for the elemental results that come from other instruments mounted on the landing platform); (iii) to determine how mineralogy changes with depth. The utility of WatSen is that it will not only detect the presence of water, but will also be able to record which minerals are present and their chemistry; it is also sensitive to many organic species. WatSen is a new instrument concept specifically designed to search for clues of the presence of water, and to look for evidence of life on Mars.
Which exoplanetary systems could harbour habitable planets?
Authors: Jones Barrie W. , Sleep P. Nick , Underwood David R.
Published: October 2006

Habitable planets are likely to be broadly Earth-like in composition, mass and size. Masses are likely to be within a factor of a few Earth masses – we call such planets Earth-mass planets. It is important to find such planets. Currently, we do not have sufficiently sensitive techniques to detect planets with such small masses, except in rare circumstances. It is thus necessary to model the known exoplanetary systems to see whether Earth-mass planets could be present. In particular, we need to establish whether such planets could be present in the classical habitable zone (HZ), or whether the giant planets that we know to be present have gravitationally ejected Earth-mass planets or prevented their formation. We have answered this question by applying computer models to the 152 exoplanetary systems known as of 18 April 2006 that are sufficiently well characterized for our analysis. For systems in which there is a giant planet interior to the HZ, which must have got there by migration, there are two cases considered: first, the case when the migration of the giant planet across the HZ has not ruled out the existence of an Earth-mass planet in the HZ; second, the case where it has. In the former case we have found that 60% of the 152 systems offer safe havens to Earth-mass planets across greater than 20% of the HZ width. We regard such systems as being habitable today. We have also estimated whether habitability is possible for 1000 Myr into the past (provided that this period post-dates the heavy bombardment of planets in the HZ). Of the 143 systems that are susceptible to this second analysis, we find that about 50% offer habitability sustained over 1000 Myr. If giant planets interior to the HZ rule Earth-mass planets, then 60% and 50% fall to 7% in both cases.
Uptake and sequestration of atmospheric CO2 in the Labrador Sea deep convection region
Authors: DeGrandpre M. D. , Körtzinger A. , Send U. , Wallace D. W. R. , Bellerby R. G. J.
Published: October 2006

The Labrador Sea is an important area of deep water formation and is hypothesized to be a significant sink for atmospheric CO2 to the deep ocean. Here we examine the dynamics of the CO2 system in the Labrador Sea using time‐series data obtained from instrumentation deployed on a mooring near the former Ocean Weather Station Bravo. A 1‐D model is used to determine the air‐sea CO2 uptake and penetration of the CO2 into intermediate waters. The results support that mixed‐layer pCO2 remained undersaturated throughout most of the year, ranging from 220 μatm in mid‐summer to 375 μatm in the late spring. Net community production in the summer offset the increase in pCO2 expected from heating and air‐sea uptake. In the fall and winter, cooling counterbalanced a predicted increase in pCO2 from vertical convection and air‐sea uptake. The predicted annual mean air to sea flux was 4.6 mol m−2 yr−1 resulting in an annual uptake of 0.011 ± 0.005 Pg C from the atmosphere within the convection region. In 2001, approximately half of the atmospheric CO2 penetrated below 500 m due to deep convection.
Halogen emissions from a small volcanic eruption: Modeling the peak concentrations, dispersion, and volcanically induced ozone loss in the stratosphere
Authors: Millard G. A. , Mather T. A. , Pyle D. M. , Rose W. I. , Thornton B.
Published: October 2006

Aircraft measurements in the Hekla, Iceland volcanic plume in February 2000 revealed large quantities of hydrogen halides within the stratosphere correlated to volcanic SO2. Investigation of the longer‐term stratospheric impact of these emissions, using the 3D chemical transport model, SLIMCAT suggests that volcanic enhancements of H2O and HNO3 increased HNO3·3H2O particle availability within the plume. These particles activated volcanic HCl and HBr, enhancing model plume concentrations of ClOx (20 ppb) and BrOx (50 ppt). Model O3 concentrations decreased to near‐zero in places, and plume average O3 remained 30% lower after two weeks. Reductions in the model O3 column reduced UV shielding by 15% for 2 days. Plume incorporation into the winter polar vortex after 1 March elevated model vortex Cly and Bry by 0.15 ppb and 7 ppt respectively, and doubled vortex ClOx and BrO. Model results agree quantitatively with the observations made by the DC‐8 aircraft.
Multi‐objective calibration of forecast ensembles using Bayesian model averaging
Authors: Vrugt Jasper A. , Clark Martyn P. , Diks Cees G. H. , Duan Qinyun , Robinson Bruce A.
Published: October 2006

Bayesian Model Averaging (BMA) has recently been proposed as a method for statistical postprocessing of forecast ensembles from numerical weather prediction models. The BMA predictive probability density function (PDF) of any weather quantity of interest is a weighted average of PDFs centered on the bias‐corrected forecasts from a set of different models. However, current applications of BMA calibrate the forecast specific PDFs by optimizing a single measure of predictive skill. Here we propose a multi‐criteria formulation for postprocessing of forecast ensembles. Our multi‐criteria framework implements different diagnostic measures to reflect different but complementary metrics of forecast skill, and uses a numerical algorithm to solve for the Pareto set of parameters that have consistently good performance across multiple performance metrics. Two illustrative case studies using 48‐hour ensemble data of surface temperature and sea level pressure, and multi‐model seasonal forecasts of temperature, show that a multi‐criteria formulation provides a more appealing basis for selecting the appropriate BMA model.
Climate and hydrographic variability in the Indo‐Pacific Warm Pool during the last millennium
Authors: Newton Alicia , Thunell Robert , Stott Lowell
Published: October 2006

Planktonic foraminiferal Mg/Ca and δ18O derived sea surface temperature and salinity records from the Makassar Strait, Indonesia, show a long‐term cooling and freshening trend, as well as considerable centennial‐scale variability during the last millennium. The warmest temperatures and highest salinities occurred during the Medieval Warm Period (MWP), while the coolest temperatures and lowest salinities occurred during the Little Ice Age (LIA). These changes in the western Pacific, along with observations from other high resolution records indicate a regionally coherent southern displacement of the Inter‐tropical Convergence Zone during the LIA, with more arid conditions in the northern tropics and wetter conditions in the southern tropics.
Constraining the composition and thermal state of the mantle beneath Europe from inversion of long‐period electromagnetic sounding data
Authors: Khan A. , Connolly J. A. D. , Olsen N.
Published: October 2006

We reexamine the problem of inverting C responses, covering periods between 1 month and 1 year collected from 42 European observatories, to constrain the internal structure of the Earth. Earlier studies used the C responses, which connect the magnetic vertical component and the horizontal gradient of the horizontal components of electromagnetic variations, to obtain the conductivity profile of the Earth's mantle. Here, we go beyond this approach by inverting directly for chemical composition and thermal state of the Earth, rather than subsurface electrical conductivity structure. The primary inversion parameters are the composition of the Earth's mantle within the system CaO‐FeO‐MgO‐Al2O3‐SiO2 and geotherm. Given these parameters, we calculate mineral modes at the prevailing physical conditions and combine these with laboratory‐based models for the conductivity of individual minerals to estimate the bulk Earth electrical conductivity structure from which C responses are calculated. To further constrain the radial density profile, we also invert for mass and moment of inertia. The results agree with earlier geophysically derived conductivity and seismic velocity models and confirm that inversion of geophysical data for compositional parameters, planetary composition, and thermal state is feasible. The inversion indicates most probable lower mantle geothermal gradients of ∼0.58 K/km, core mantle boundary temperatures of ∼2900°C, bulk Earth molar Mg/Si ratios of ∼1.1, intermediate between the chondrite and pyrolite models, and no significant change in mantle composition across the 670‐km seismic discontinuity.
Quantum invariants, modular forms, and lattice points II
Authors: Hikami Kazuhiro
Published: October 2006

We study the SU(2) Witten-Reshetikhin-Turaev (WRT) invariant for the Seifert fibered homology spheres with M-exceptional fibers. We show that the WRT invariant can be written in terms of (differential of) the Eichler integrals of modular forms with weight 1∕2 and 3∕2. By use of nearly modular property of the Eichler integrals we shall obtain asymptotic expansions of the WRT invariant in the large-N limit. We further reveal that the number of the gauge equivalent classes of flat connections, which dominate the asymptotics of the WRT invariant in N→∞, is related to the number of integral lattice points inside the M-dimensional tetrahedron.
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2
-coverage-dependent CO oxidation on reduced TiO2(110): A first principles study
Authors: Pillay Devina , Hwang Gyeong S.
Published: October 2006

First principles periodic slab calculations based on gradient-corrected density functional theory have been performed to investigate CO oxidation on rutile TiO2(110) at varying O2 coverages (θ=1, 2, and 3, where θ is defined as the number of O2 per oxygen vacancy). For each coverage we only present the reaction of CO with oxygen species in the most stable configuration. Our results show a significant variation in the oxidation activation energy with O2 coverage.
Hydrogen bonding in the LaNi3BH3 hydride
Authors: Orgaz Emilio , Aburto Andrea
Published: October 2006

The electronic structure of the intermetallic LaNi3B as well as the novel hydride LaNi3BH3 have been theoretically investigated by means of quantum chemistry methods. We employed a mixed approach to investigate the electronic structure of these compounds: state-of-the-art energy band calculations and molecular cluster computations. We computed the energy bands and the total and partial density of states using both the linear-augmented plane waves and projector-augmented wave methods. In addition the electronic structure of three representative clusters of the local environment of Ni atoms was investigated by quantum chemistry ab initio molecular calculations. In this report, we discuss the chemical bonding and we investigated the H site occupancy energies and correlate this estimate with the occupancy fraction and metal-hydrogen distances experimentally observed.
Nonlinear diffusion equation and nonlinear external force: Exact solution
Authors: Assis P. C. , da Silva P. C. , da Silva L. R. , Lenzi E. K. , Lenzi M. K.
Published: October 2006

The solutions of the nonlinear diffusion equation ∂tρ=r1−ND∂r{rN−1−θργ∂r[r−ηρν]}−r1−N∂r[rN−1Fρ] are investigated by considering the presence of an external force F which exhibits an explicit dependence on the distribution. First, the stationary case is considered; after that the dynamical case, i.e., the case dependent on time. The stationary solution is obtained by considering the external force F(r;ρ)=F1(r)+F2(r)[ρ(r)]ν+γ−1 and the result found is related to the distributions which emerge from the Tsallis statistics or the Boltzmann-Gibbs statistics. The dynamical solution is investigated by considering the external force F(r,t;ρ)=−k(t)r+K∕r1+θ+η[ρ(r,t)]γ+ν−1 and related to the Levy distributions in the asymptotic limit. In both cases, the solutions are expressed in terms of the q-exponentials and the q-logarithmics functions which emerge from the Tsallis formalism.
Hole localization in Al doped silica: A DFT+U description
Authors: Nolan Michael , Watson Graeme W.
Published: October 2006

Despite density functional theory (DFT) being the most widely used ab initio approach for studying the properties of oxide materials, the modeling of localized hole states in doped or defective oxides can be a challenge. The electronic hole formed when silica is doped with aluminum is such a defect, for which a DFT description of the atomic and electronic structures has previously been found to be inconsistent with experiment, while Hartree-Fock provides a consistent description. We have applied the DFT+U approach to this problem and find that the structural distortions around the dopant are consistent with experimental data as well as earlier cluster calculations using Hartree-Fock and perturbation theory. A hole state is found 1.1eV (1.6eV experimentally) above the top of the valence band with localization of spin on the oxygen atom which shows the elongated Al–O distance. A formation energy of 5.7eV is found. We discuss implications for using DFT+U to model defective oxide systems with O 2p holes.