bluuebunny/crossref_metadata_2025 huggingface dataset:
Different adaptive responses of leaf physiological and biochemical aspects to drought in two contrasting populations of seabuckthorn
Authors: Xu Gang , Duan Baoli , Li Chunyang
Published: April 2008

Two contrasting populations of seabuckthorn ( Hippophae rhamnoides L.) from western China were employed to study their differences in adaptive responses to drought. The Daofu population was from a wetter upland climate region, whereas the Dingxi populations was from a drier lowland climate region. A completely randomized design with two factors, two populations and two watering regimes (100% and 25% of the soil water holding capacity), was used. In both populations, drought significantly decreased growth and the net photosynthesis rate (A), and significantly increased the root/shoot ratio (RS), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX) and ascorbate peroxidase (APX) activities, and abscisic acid (ABA) and proline contents. Compared with the Daofu population, drought induced a greater RS value, higher CAT, GPX, and APX activities, and a higher ABA content in the Dingxi population, whereas the gas exchange traits, for example, the stomatal limitation value (LS) and intercellular CO2 concentration (Ci), were less responsive to drought in the Dingxi population. The two populations may have developed different strategies to tolerate drought, such as different pathways to dissipate excess absorbed light energy, to resist oxidative stress, and to keep water status. Such factors enable the Dingxi population to tolerate drought better than the Daofu population.
Controlling coarse woody debris inventory quality: taper and relative size methods
Authors: Woodall C. W. , Westfall J. A.
Published: April 2008

Accurately measuring the dimensions of coarse woody debris (CWD) is critical for ensuring the quality of CWD estimates and, hence, for accurately estimating forest ecosystem attributes (e.g., CWD carbon stocks). To improve the quality of CWD dimensional measurements, the distribution of taper (ratio of change in diameter and length) and relative size (RS; ratio of length and large-end diameter) of CWD pieces across the US were examined. Additionally, an outlier identification technique was developed by predicting the median and interquartile range of taper and RS as a function of large-end diameter, length, and decay class by major species group. The median CWD taper and RS across the US were 1.268 cm/m and 0.280 m/cm, respectively, with notable outliers. The taper and RS outlier identification protocol rapidly identified nearly 3% of study observations as outliers. Incorporation of CWD taper and RS outlier identification protocols into field data recorders may allow efficient control of measurement errors during field inventories.
Silvicultural responses of two spruce plantations to midrotation commercial thinning in New Brunswick
Authors: Pelletier Gaetan , Pitt Douglas G.
Published: April 2008

A midrotation commercial thinning experiment conducted in two independent spruce plantations compared several tree selection strategies as both early (age 19 or 24 years) single and double (again at age 30 or 34 years) entries over a 16 year period. A delayed (age 30 or 32 years) single-entry thinning and unthinned portions of the plantations served as references for the other treatments. With the exception of 50% systematic row thinnings, removal intensities were held relatively constant at about 40% of stand basal area. All of the thinning treatments satisfied the objectives of focusing diameter and volume growth on a reduced number of stems and making merchantable volume available during the rotation. Early single-entry thinning allowed 30–50 m3/ha to be harvested, increasing quadratic mean diameter and mean merchantable volume per stem at the end of the observation period by 10% and 24%, respectively, over unthinned stands. A second thinning removed an additional 48–64 m3/ha and increased diameter and volume gains to 25% and 71%, respectively. Only marginal differences were observed between the tree-selection strategies, and there were no overall gross total or gross merchantable volume gains or losses associated any of the thinning treatments relative to the unthinned plantations.
Dynamics of jack pine at the southern range boundary in downeast Maine
Authors: Barton Andrew M. , Grenier Daniel J.
Published: April 2008

Great Wass Island in Maine supports a large population of Pinus banksiana Lamb. (jack pine) at its southern range boundary. Nearly monospecific stands occur on outcrops and coastal plateau bogs. In contrast to typical populations of this species, six stands exhibited old trees, multiaged structure, and continuous but pulsed establishment despite a lack of widespread fire. Unfavorable soil conditions appear to explain the presence of self-perpetuating populations in this study area, across the geographic range for P. banksiana, and for similar shade-intolerant pine species. Pinus banksiana stands on outcrops exhibited synchronous age structure peaks and included many trees over 150 years old. In contrast, coastal plateau bog stands were younger, were not synchronized in terms of age structure, and contained few large dead trees, suggesting turn-of-the-20th century invasion of these bogs. Analysis of historical aerial photographs furthermore reveals substantial infilling of bogs by P. banksiana since 1940. Although it appears to be an inconsistent and slow process, coastal plateau bog infilling warrants further investigation because of the regional rarity of this ecosystem type.
Effect of interannual climate variations on radial growth of jack pine provenances in Petawawa, Ontario
Authors: Savva Y. , Bergeron Y. , Denneler B. , Koubaa A. , Tremblay F.
Published: April 2008

Effect of interannual climate variations on radial growth was compared among jack pine ( Pinus banksiana Lamb.) of diverse geographical origins in a 41-year-old common-garden experiment in Petawawa, Ontario. Provenance experiments established from seeds transferred from different parts of a species range (from the northern United States to northern Canada) to the same environment might be considered as a simulation model of climate change and a shift of climate zones. The following questions are addressed: Did the response of growth to interannual climate variations differ among the provenances transferred within the experimental site? What climatic factors affect interannual growth variations of jack pine provenances? Tree-ring chronologies for 16 populations were developed for the period 1970–2004. The best climate predictors of radial growth were precipitation of June and March of the current year and precipitation of December of the previous year. Although, climatic factors affecting growth were similar between the provenances, absolute radial growth was proportional to the growth potential of the provenances. We conclude that variability due to seeds origins is not a significant source of variation for dendroclimatic studies of jack pine. Increased frequency of summer droughts might result in a growth decrease of jack pine.
Patterns of throughfall deposition along a transect in forest edges of silver birch and Corsican pine
Authors: Wuyts K. , De Schrijver A. , Staelens J. , Gielis M. , Geudens G. , Verheyen K.
Published: April 2008

In two adjacent forest stands in Flanders, one dominated by Corsican pine ( Pinus nigra subsp. laricio Maire) and another dominated by silver birch ( Betula pendula Roth), throughfall deposition was monitored along a transect perpendicular to the forest edge exposed to the prevailing wind direction. Throughfall deposition of Na+, K+, Ca2+, Mg2+, NH4+, NO3–, Cl–, and SO42–was examined on forest edge patterns expressed in the depth of influence of the edge effect (forest edge distance) and the level of enhancement at the edge (forest edge enhancement). In addition, an integrated forest edge enhancement factor was computed that incorporates these two parameters. Our results show that the edge effects on throughfall deposition of Na+, Cl–, the sum of so-called base cations, the sum of potentially acidifying ions, and the sum of inorganic nitrogen (NH4+ + NO3–) are more pronounced in the pine stand. The edge zone of the pine stand receives as a result of the edge effect 9.4 times more extra potentially acidifying ions and 12.7 times more extra inorganic nitrogen than the birch stand. We conclude that an appropriate design or conversion of the edge structure, from high-density Corsican pine plantations into lower density deciduous forests, can reduce the input of acidifying and eutrophying pollutants in the forest edge.
Tree species mediated effects on leaf litter dynamics in pure and mixed stands of oak and beech
Authors: Jonard Mathieu , Andre Frederic , Ponette Quentin
Published: April 2008

This study aimed to evaluate the relative importance of the factors whereby tree species composition can influence leaf litter dynamics. Leaf litter production and chemical composition were measured in pure and mixed stands of oak ( Quercus petraea Liebl.) and beech ( Fagus sylvatica L.). Pure and mixed leaf litter of both species were incubated in each stand type to assess separately the environmental, litter quality, and litter mixture effects on decomposition. To better understand the environmental effects, ground climate was measured in the different stands and the effects of soil water content on decomposition were evaluated using roofs to simulate drought conditions. Although total leaf litter amounts were not affected by stand composition, leaf decomposition varied with litter quality and with the environmental conditions. In the same environment, oak leaf litter disappeared on average 1.7 times faster than beech leaf litter. Decomposition of oak leaves increased significantly in the mixed-species litterbags. In contrast, the overall mass loss of the mixed litter tallied with the mass loss estimated by examining the decomposition of the component litter separately (additive-effect hypothesis). The effects of stand type appeared in the third year of incubation: leaf mass loss of both species was greater in the beech stand. In addition, soil water content affected leaf decomposition: the oak and beach leaf mass losses dropped by 24% and 17%, respectively, in the dry modality.
The influence of basswood (Tilia americana) and soil chemistry on soil nitrate concentrations in a northern hardwood forest
Authors: Page Blair D. , Mitchell Myron J.
Published: April 2008

In the Arbutus Lake Watershed in the Adirondack Mountains, New York, two nearly adjacent catchments (14 and 15) varied significantly in volume-weighted stream water nitrate (NO3) export (54 and 17 μequiv.·L–1, respectively; P < 0.001). The most notable differences between the catchments were that Catchment 14 had significantly higher soil Ca concentrations and patches of basswood ( Tilia americana L.). We evaluated the possible contributions of basswood and soil Ca concentrations to soil water NO3 concentrations. Among the major overstory tree species, basswood leaf litter had the lowest C:N ratios, highest Ca concentrations, and among the lowest lignin:N ratios. Basswood basal area was significantly related to soil water NO3 concentrations (R = 0.46, P = 0.01). Forest floor and mineral soil Ca concentrations were positively correlated with basswood basal area and negatively correlated with American beech ( Fagus grandifolia Ehrh.) basal area. Our results suggest that a relatively low-density, calciphilic species such as basswood may create, given the proper soil conditions, hotspots with elevated soil water NO3 concentrations. These hotspots result from the convergence of high soil Ca concentrations, due mostly to soil geology, with relatively labile litter substrate available for N mineralization and nitrification.
Tree rings of Pinus nigra from the Vienna basin region (Austria) show evidence of change in climatic sensitivity in the late 20th century
Authors: Leal Sofia , Eamus Derek , Grabner Michael , Wimmer Rupert , Cherubini Paolo
Published: April 2008

The width of tree rings of Pinus nigra Arn. trees growing near the ecological limits for the species, in the Vienna basin, Austria, showed a strong and positive correlation with spring–summer precipitation, indicating a dependence of growth on water availability during the growing season. During the late 20th century, tree rings grew wider than expected given the predicted relationship between rainfall and growth rate observed in the early 20th century. This resulted in models of the relationship between climate and growth rate systematically overestimating the total spring–summer (April–July) precipitation over the last half of the 20th century. Analysis of the temporal stability of the relationship between tree growth and climate variables shows a decrease in the sensitivity of the growth of tree rings to spring–summer precipitation towards the end of the 20th century. This change in sensitivity suggests that tree growth was no longer primarily dependent on water availability. We propose that there was an improvement in water-use efficiency arising from a stimulation of photosynthesis and declining stomatal conductance as a consequence of the increasing CO2 concentration in the atmosphere and that this effect was enhanced by a relatively high input of N due to the proximity of N emission sources.
Characterization of diameter distribution data in near-natural forests using the Birnbaum–Saunders distribution
Authors: Podlaski Rafał
Published: April 2008

The purpose of this study is to investigate the suitability of the Birnbaum–Saunders distribution to model diameter at breast height (DBH) distributions of near-natural complex structure silver fir ( Abies alba Mill.) – European beech ( Fagus sylvatica L.) forests. The investigations were carried out in Świętokrzyski National Park, situated in Central Poland. To estimate the parameters of the Birnbaum–Saunders distribution, three methods were used: the maximum likelihood method (MLE) and the mean–mean estimator, the modified moment method (MME), and the graphical method (GME). The empirical DBH distributions in near-natural fir–beech stands, which arose according to the model taking into account the overlapping of fir mortality and beech regeneration, were generally conformed to the Birnbaum–Saunders distribution. In such forests, the Birnbaum–Saunders distribution approximated the empirical DBH distributions more precisely than the Weibull and gamma distributions.
Growth and physiology of loblolly pine in response to long-term resource management: defining growth potential in the southern United States
Authors: Samuelson Lisa J. , Butnor John , Maier Chris , Stokes Tom A. , Johnsen Kurt , Kane Michael
Published: April 2008

Leaf physiology and stem growth were assessed in loblolly pine ( Pinus taeda L.) in response to 10 to 11 years of treatment with weed control (W), weed control plus irrigation (WI), weed control plus irrigation and fertigation (WIF), or weed control plus irrigation, fertigation, and pest control (WIFP) to determine whether increased resource availability can push productivity of loblolly pine closer to its biological growth potential expressed in favorable, exotic environments. Maximum basal area and stem biomass were 41 m2·ha–1 and 172 Mg·ha–1, respectively, in response to fertigation. Stemwood biomass production was positively and linearly related to basal area. Belowground woody biomass was highest in the WIF and WIFP treatments and averaged 50 Mg·ha–1, but the W and WI treatments exploited a greater area of soil with low-density coarse roots. Fertigation increased foliar nitrogen concentration and foliage biomass, but treatment had no effect on leaf physiological parameters or growth efficiency. Comparison with growth rates reported for loblolly pine in Hawaii revealed that loblolly pine grown in its native range can produce the high yields observed in exotic environments when stands are below maximum carrying capacity.
Tree rings used to assess time since death of deadwood of different decay classes in beech and silver fir forests in the central Apennines (Molise, Italy)
Authors: Lombardi Fabio , Cherubini Paolo , Lasserre Bruno , Tognetti Roberto , Marchetti Marco
Published: April 2008

We investigated the relationship between time since death and morphological characteristics of Abies alba Mill. (European silver fir) and Fagus sylvatica L. (European beech) stumps in two forest stands in the central Apennines. At each site, 15 or 16 living trees were selected, and increment cores were collected to build master ring-width chronologies. For both sites, cross sections were collected from stumps. Samples were assigned to visually discernible decay classes, and their death date dendrochronologically determined. Using cross-dating techniques, stumps cross-dated significantly with standard chronologies, and it was possible to assign a year of death to 77% and 69% of sampled A. alba and F. sylvatica stumps, respectively. Analysis of the time since death of the stumps suggests that the two species have similar decay rates, although A. alba was faster in passing from class 2 to class 3. However, this study revealed a continuum through decay classes and showed a high variability in the transition rate from one class to another. Overall, information obtained using dendrochronological techniques was valuable for assessing deadwood decomposition rates. The variability found in stump decomposition rates indicates that existing decay classification schemes, although providing information on decomposition timing, are hardly applicable to these forest stands and that the relationship between qualitatively assessed decay classes and time since death of trees appears to be rather weak.
Multi-year ecosystem response to hemlock woolly adelgid infestation in southern New England forests
Authors: Orwig David A. , Cobb Richard C. , D’Amato Anthony W. , Kizlinski Matthew L. , Foster David R.
Published: April 2008

The introduced hemlock woolly adelgid (HWA) ( Adelges tsugae Annand) has generated widespread tree decline and substantial mortality of eastern hemlock ( Tsuga canadensis (L.) Carrière) throughout the eastern United States. To assess the magnitude of ecosystem response to this disturbance, we conducted a multi-year study of forests with and without damage from HWA. Infested forests had significantly higher HWA-induced foliar loss and significantly lower forest floor C:N ratios and soil organic matter than uninfested forests. There were no significant soil temperature differences among stand types, although infested stands did have lower forest floor soil moisture than uninfested stands. Net nitrification and net N mineralization rates were significantly higher in infested versus uninfested forests by the second and third year of this study, respectively. In addition, total N pools and resin bag capture of NH4 and NO3 were significantly higher in infested versus uninfested forests throughout this study. Increases in N were likely due to a combination of factors including enhanced decomposition, reduced uptake of water and N by declining trees, sparse understory vegetation, and N-enriched throughfall from infested canopies. These results confirm that invasive pests can initiate substantial changes in ecosystem function soon after infestation occurs, prior to substantial overstory mortality or understory reorganization.
Opportunities and costs of intensification and clustering of forest management activities
Authors: Mathey Anne-Hélène , Krcmar Emina , Innes John , Vertinsky Ilan
Published: April 2008

The intensification of forest management in Canada has been advocated as a possible solution to the conundrum that increasing demand for conservation areas and increasing pressure for timber production have created. The benefits and disadvantages of intensive forest management in the context of the Canadian boreal forest are unclear and reaching conclusions about its general value from stand analyses may be difficult. In this study, a boreal forest in Ontario has been used to investigate the potential of intensive management to generate financial revenues and meet management constraints on volume flow and old-growth retention. Two aspects of intensive forest management are considered: intensive silviculture and concentrated harvest activities. The plans are generated with a decentralized planning approach based on cellular automata. The results for the case study show that increasing silviculture intensity can help fulfill high timber flow requirements under strict conservation requirements. This comes at the cost of reduced net revenues but from a smaller timber harvesting landbase. The main trade-offs found were those between harvest flow and financial benefits. Clustering both protected areas and harvest operations could help achieve the conservation and timber-related objectives simultaneously by improving the habitat value of conserved areas and decreasing the operational costs in harvested areas.
Effects of forest floor organic layer and root biomass on soil respiration following boreal forest fire
Authors: Singh S. , Amiro B. D. , Quideau S. A.
Published: April 2008

Soil respiration and its spatial and temporal variation were studied at three boreal forest sites in central Saskatchewan, Canada, burned in 1998, 1989, and 1977. Soil respiration, soil temperature, and organic layer thickness were measured at 100 points in a grid pattern of 2 m × 2 m at each site in 2004 and 2005. The mean within-site spatial coefficient of variation was 35%, and the measurements were not spatially autocorrelated. We found no significant difference in variance between the two youngest sites (P > 0.05), whereas the older site showed significantly lower variance (P < 0.05). Soil respiration was not correlated with the forest floor organic layer thickness at any of the sites (R2 < 0.1). Removal of the forest floor layer reduced the soil respiration by 17% to 38%, depending on the site. Thus, the respiration from the mineral soil seemed to contribute a major fraction of the total soil respiration (62%–83%). Soil respiration was positively linearly related to the fine root biomass (R2 = 0.63–0.85, P < 0.05) at all sites. We conclude that variation in root biomass has a larger effect than differential forest floor organic layers on variation in soil respiration in young boreal postfire forests.
Reproductive output of ponderosa pine in response to thinning and prescribed burning in western Montana
Authors: Peters Gregory , Sala Anna
Published: April 2008

Thinning and thinning followed by prescribed fire are common management practices intended to restore historic conditions in low-elevation ponderosa pine ( Pinus ponderosa Dougl. ex P. & C. Laws.) forests of the northern Rocky Mountains. While these treatments generally ameliorate the physiology and growth of residual trees, treatment-specific effects on reproductive output are not known. We examined reproductive output of second-growth ponderosa pine in western Montana 9 years after the application of four treatments: thinning, thinning followed by spring prescribed fire, thinning followed by fall prescribed fire, and unthinned control stands. Field and greenhouse observations indicated that reproductive traits vary depending on the specific management treatment. Cone production was significantly higher in trees from all actively managed stands relative to control trees. Trees subjected to prescribed fire produced cones with higher numbers of filled seeds than trees in unburned treatments. Seed mass, percentage germination, and seedling biomass were significantly lower for seeds from trees in spring burn treatments relative to all others and were generally higher in trees from fall burn treatments. We show for the first time that thinning and prescribed-burning treatments can influence reproductive output in ponderosa pine.
Effects of stem anatomical and structural traits on responses to stem damage: an experimental study in the Bolivian Amazon
Authors: Romero Claudia , Bolker Benjamin M.
Published: April 2008

Persistence of tree species in a habitat depends on their ability to avoid and respond to disturbance-related damage. Responses to stem damage vary among species but typically include bark wound closure and prevention of xylem decay spread. These responses are associated with anatomical, structural, and physiological traits. This study explores how xylem (vessel size and (or) abundance, parenchyma abundance, ray width, and wood density) and phloem (bark thickness, proportion of live inner bark, ray width and (or) dilation, inter-ray distance, and tissue density) traits relate to responses to stem damage in seven species from the Bolivian Amazon. Rates of bark wound closure and radial xylem decay penetration were compared 2 years after experimental damage. A species that closed bark wounds rapidly (100% in Chorisia speciosa A. St.-Hil.) was not efficient at constraining xylem radial decay spread (1.7 mm). The opposite was true for Pseudolmedia laevis (Ruiz & Pav.) J.F. Macbr., a species that closed wounds slowly (30%) but efficiently controlled decay spread (0.5 mm). The relationship between anatomical and (or) structural traits and damage response variables revealed that species with favorable traits for rapid wound closure (e.g., widely dilating rays) had traits that favored xylem decay spread (e.g., low wood density). It is plausible that this apparent trade-off is based on physiological and phylogenetic constraints.
Assessing prediction errors of generalized tree biomass and volume equations for the boreal forest region of west-central Canada
Authors: Case Bradley S. , Hall Ronald J.
Published: April 2008

Aboveground tree biomass and volume are required inputs to models that estimate carbon budgets and ecosystem productivity. Generalized equations are often used to estimate biomass and volume when local equations are unavailable. This study determined whether there was a concomitant increase in prediction error from increasing levels of equation generalization. Local site, generalized regional, and generalized national allometric equations were compared for 10 species distributed across 119 sites in a region defined by west-central Canada. This study employed regression fit statistics and two prediction error metrics, the average prediction error (APE) from the prediction error sum of squares (PRESS) statistic and mean prediction bias. The APE was 9, 12, and 25 kg of biomass per tree for local site, generalized regional, and national equations, respectively. The mean prediction bias for biomass and volume were statistically similar between local level and generalized regional equations across all species. Predictions from generalized national equations were statistically similar for 5 of 10 species when compared with those from local site and generalized regional equations. While local site equations were most accurate for a given site, results indicate that generalized regional equations will produce reasonable estimates of biomass and volume at sites in this region of Canada.
BIOLOGICALLY BASED TOP-DOWN ATTENTION MODULATION FOR HUMANOID INTERACTIONS
Authors: MORÉN JAN , UDE ALEŠ , KOENE ANSGAR , CHENG GORDON
Published: April 2008

An adaptive perception system enables humanoid robots to interact with humans and their surroundings in a meaningful context-dependent manner. An important foundation for visual perception is the selectivity of early vision processes that enables the system to filter out low-level unimportant information while attending to features indicated as important by higher-level processes by way of top-down modulation. We present a novel way to integrate top-down and bottom-up processing for achieving such attention-based filtering. We specifically consider the case where the top-down target is not the most salient in any of the used submodalities.
WHAT PEOPLE ASSUME ABOUT HUMANOID AND ANIMAL-TYPE ROBOTS: CROSS-CULTURAL ANALYSIS BETWEEN JAPAN, KOREA, AND THE UNITED STATES
Authors: NOMURA TATSUYA , SUZUKI TOMOHIRO , KANDA TAKAYUKI , HAN JEONGHYE , SHIN NAMIN , BURKE JENNIFER , KATO KENSUKE
Published: April 2008

To broadly explore the rationale behind more socially acceptable robot design and to investigate the psychological aspects of social acceptance of robotics, a cross-cultural research instrument, the Robot Assumptions Questionnaire (RAQ) was administered to the university students in Japan, Korea, and the United States, focusing on five factors relating to humanoid and animal-type robots: relative autonomy, social relationship with humans, emotional aspects, roles assumed, and images held. As a result, it was found that (1) Students in Japan, Korea, and the United States tend to assume that humanoid robots perform concrete tasks in society, and that animal-type robots play a pet- or toy-like role; (2) Japanese students tend to more strongly assume that humanoid robots have somewhat human characteristics and that their roles are related to social activities including communication, than do the Korean and the US students; (3) Korean students tend to have more negative attitudes toward the social influences of robots, in particular, humanoid robots, than do the Japanese students, while more strongly assuming that robots' roles are related to medical fields than do the Japanese students, and (4) Students in the USA tend to have both more positive and more negative images of robots than do Japanese students, while more weakly assuming robots as blasphemous of nature than do Japanese and Korean students. In addition, the paper discusses some engineering implications of these research results.
HUMAN–ROBOT COLLABORATION: A SURVEY
Authors: BAUER ANDREA , WOLLHERR DIRK , BUSS MARTIN
Published: April 2008

As robots are gradually leaving highly structured factory environments and moving into human populated environments, they need to possess more complex cognitive abilities. They do not only have to operate efficiently and safely in natural, populated environments, but also be able to achieve higher levels of cooperation and communication with humans. Human–robot collaboration (HRC) is a research field with a wide range of applications, future scenarios, and potentially a high economic impact. HRC is an interdisciplinary research area comprising classical robotics, cognitive sciences, and psychology. This paper gives a survey of the state of the art of HRC. Established methods for intention estimation, action planning, joint action, and machine learning are presented together with existing guidelines to hardware design. This paper is meant to provide the reader with a good overview of technologies and methods for HRC.
ROBOT MANZAI: ROBOT CONVERSATION AS A PASSIVE–SOCIAL MEDIUM
Authors: HAYASHI KOTARO , KANDA TAKAYUKI , MIYASHITA TAKAHIRO , ISHIGURO HIROSHI , HAGITA NORIHIRO
Published: April 2008

This paper reports on the development of a multirobot cooperation system for human–robot communication in which robots behave as if communicating by speech, while the system exchanges information through a network that maintains natural communication timing. The information exchanged through the network is based on the analysis of interhuman conversation. This system is based on a scripting language for coordinating multirobot communication, which has a merit for developers: easy development. The developed system is used for Manzai, which is a kind of a Japanese stand-up comedy mainly performed by two persons. While tempo and timing are particularly important in Manzai, the developed "robot Manzai" system received higher evaluations than the Manzai shown in a video performed by humans. We believe that this system demonstrates the potential of robots as a passive–social medium, including television and computers.
AGGREGATE QUERY PROCESSING FOR SEMANTIC WEB DATABASES: AN ALGEBRAIC APPROACH
Authors: SEID DAWIT , MEHROTRA SHARAD
Published: April 2008

As a growing number of applications represent data as semantic graphs like RDF (Resource Description Format) and the many entity-attribute-value formats, query languages for such data are being required to support operations beyond graph pattern matching and inference queries. Specifically the ability to express aggregate queries is an important feature which is either lacking or is implemented with little attention to the peculiarities of the data model. In this paper, we study the meaning and implementation of grouping and aggregate queries over RDF graphs. We first define grouping and aggregate operators algebraically and then show how the SPARQL query language can be extended to express grouping and aggregate queries.
RANDOM WALK TERM WEIGHTING FOR IMPROVED TEXT CLASSIFICATION
Authors: HASSAN SAMER , MIHALCEA RADA , BANEA CARMEN
Published: April 2008

This paper describes a new approach for estimating term weights in a document, and shows how the new weighting scheme can be used to improve the accuracy of a text classifier. The method uses term co-occurrence as a measure of dependency between word features. A random walk model is applied on a graph encoding words and co-occurrence dependencies, resulting in scores that represent a quantification of how a particular word feature contributes to a given context. Experiments performed on three standard classification datasets show that the new random walk based approach outperforms the traditional term frequency approach of feature weighting.
Dating the onset of volcanism at the Rum Igneous Centre, NW Scotland
Authors: TROLL VALENTIN R. , NICOLL GRAEME R. , DONALDSON COLIN H. , EMELEUS HENRY C.
Published: April 2008

Major volcanic activity on the Isle of Rum commenced with the eruption of thick (>100 m) intra-caldera rhyodacite ash-flow sheets fed from steep-sided feeder conduits in the proximity of the Main Ring Fault. Twenty plagioclase phenocrysts of the rhyodacite were analysed using single crystal
40
Ar/
39
Ar laser dating, yielding a mean apparent age of 60.83 ± 0.27 Ma (MSWD=3.65). On an age v. probability plot the feldspars do not, however, show a simple Gaussian distribution, but a major peak at 60.33 ± 0.21 Ma and two smaller shoulders at
c
. 61.4 Ma and 63 Ma. These older ages are interpreted to represent recycled and largely re-equilibrated feldspars. The age peak at 60.33 ± 0.21 Ma is interpreted to represent the intrusion and eruption age of the rhyodacites. This new age constraint overlaps with that for the ultrabasic intrusion, implying that the latter was already forming at depth and supplying necessary heat during the early felsic activity phase, and quickly thereafter migrated upwards to shallow structural levels and intruded the volcano's earlier deposits. Combined with previously published ages, these new age data highlight an extremely rapid succession of events at the Rum centre, the whole sequence occurring in potentially <500 ka.
Oxygen, carbon and strontium isotope constraints on the mechanisms of nappe emplacement and fluid–rock interaction along the subhorizontal Naukluft Thrust, central Namibia
Authors: MILLER JODIE A. , VIOLA GIULIO , MANCKTELOW NEIL S.
Published: April 2008

The Naukluft Thrust forms the floor thrust to the Naukluft Nappe Complex, a far-travelled, nappe stack of the Pan-African Damara belt in Namibia. The thrust tectonostratigraphy comprises three dolomitic components, a calc-mylonite horizon, and a discrete brittle fault. Stable isotope data indicate that the leading edge is characterized by positive δ
13
C values, whereas the trailing edge is characterized by negative δ
13
C values. There is a significant range in the δ
18
O values, over 15‰ in different sections, with the leading edge showing a larger range than the trailing edge. δ
18
O values are characteristic of burial dolomites and secondary dolomitization is indicated by the presence of networks above and below the Naukluft Thrust zone. The large range in δ
18
O values and variations in δ
13
C vs. δ
18
O patterns are interpreted to be the result of interaction between the precursor to the Naukluft Thrust zone dolomites and fluids derived from different footwall lithologies.
87
Sr/
86
Sr isotope ratios indicate that some fluids were derived from the basement. The data presented in this study suggest that an original carbonate-dominated horizon existed prior to thrusting and that the basal thrust of the nappe complex exploited this horizon.
Geochronology and geodynamics of Scottish granitoids from the late Neoproterozoic break-up of Rodinia to Palaeozoic collision
Authors: OLIVER GRAHAME J.H. , WILDE SIMON A. , WAN YUSHENG
Published: April 2008

Thirty-seven granitoids from Scotland have been dated using the sensitive high-resolution ion microprobe zircon method. Granitoids were intruded during: (1) crustal stretching at
c
. 600 Ma after Rodinia broke up (A-types); (2) the Grampian event of crustal thickening when the Midland Valley Arc terrane collided with Laurentia at
c
. 470 Ma (S-types); (3) erosion and decompression of the over-thickened Laurentian margin at
c
. 455 Ma (S-types); (4) subduction of Iapetus Ocean lithosphere under Laurentia starting at 430 Ma (I-types); (5) roll-back beginning at 420 Ma (I-types); (6) bilateral slab break-off and lithospheric delamination at 410 Ma (I- and S-type granites) when Baltica hard-docked against the Northern Highland terrane and Avalonia soft-docked against the Grampian Highland terrane. Far-field Acadian events at 390 Ma were recorded by I-type granites intruded along active sinistrally transpressive faults. I-types formed in lower crustal hot zones above subduction zones, whereas S-types formed in lower crustal hot zones above lithospheric windows through which hot asthenosphere had risen.
Role of porosity and dehydration reaction on the deformation of hot-pressed serpentinite aggregates
Authors: ARKWRIGHT J.C. , RUTTER E.H. , BRODIE K.H. , LLANA-FúNEZ S.
Published: April 2008

Experimental deformation of hot-pressed powders of lizardite serpentinite was carried out to study the effect of the dehydration reaction to olivine + talc + water under controlled pore water pressure. Use of a porous aggregate ensured free movement of pore fluid into or out of the specimen in response to volume changes. The dehydration reaction further increases the porosity of the sample, causing weakening, but progressive pore collapse leads to strain hardening. At low strain rates, a transition to linear–viscous flow was inferred to be caused by the formation of transiently fine-grained olivine in the dehydration reaction. The inability of the rock to support high loads during dehydration at low strain rates means that the production of high-pressure water by dehydration and its subsequent expulsion will favour seismogenic failure in the surrounding rocks not directly involved in the dehydration reaction, rather than the serpentinite itself.
The tectonothermal evolution and provenance of the Tyrone Central Inlier, Ireland: Grampian imbrication of an outboard Laurentian microcontinent?
Authors: CHEW D.M. , FLOWERDEW M.J. , PAGE L.M. , CROWLEY Q.G. , DALY J.S. , COOPER M. , WHITEHOUSE M.J.
Published: April 2008

The Tyrone Central Inlier is a metamorphic terrane of uncertain affinity situated outboard of the main Dalradian outcrop (south of the Fair Head–Clew Bay Line) and could represent sub-arc basement to part of the enigmatic Midland Valley Terrane. Using a combination of isotopic, structural and petrographic evidence, the tectonothermal evolution of the Tyrone Central Inlier was investigated. Sillimanite-bearing metamorphic assemblages (
c
. 670 °C, 6.8 kbar) and leucosomes in paragneisses are cut by granite pegmatites, which post-date two deformation fabrics. The leucosomes yield a weighted average
207
Pb/
206
Pb zircon age of 467 ± 12 Ma whereas the main fabric yields a
40
Ar–
39
Ar biotite cooling age of 468 ± 1.4 Ma. The pegmatites yield 457 ± 7 Ma and 458 ± 7 Ma Rb–Sr muscovite–feldspar ages and
40
Ar–
39
Ar step-heating plateaux of 466 ± 1 Ma and 468 ± 1 Ma, respectively. The metasedimentary rocks yield Palaeoproterozoic Sm–Nd model ages and laser ablation inductively coupled plasma mass spectrometry detrital zircon U–Pb analyses from a psammitic gneiss yield age populations at 1.05–1.2, 1.5, 1.8, 2.7 and 3.1 Ga. Combined, these data permit correlation of the Tyrone Central Inlier with either the Argyll or the Southern Highland Group of the Dalradian Supergroup. The inlier was thus part of Laurentia onto which the Tyrone ophiolite was obducted.
Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia
Authors: NAISH DARREN , MARTILL DAVID M.
Published: April 2008

Completing our survey of British non-avian dinosaurs, we here review the ornithischians of Britain. Heterodontosaurids are present in the Lower Cretaceous Lulworth Formation of Dorset, and a few earlier possible records imply a long presence in the region of this clade. Britain's thyreophoran record is rich and includes the earliest well-represented taxon,
Scelidosaurus
, as well as Middle Jurassic stegosaurs and ankylosaurs including a reasonably good Cretaceous record of polacanthids and nodosaurids. Cretaceous stegosaurs are known only from fragmentary remains, but the proposal that stegosaurs were present as early as the Rhaetian is rejected. Among British iguanodontian ornithopods, the possible dryosaurid
Callovosaurus
is the oldest global record whereas the proposed synonymy of
Cumnoria
with
Camptosaurus
requires confirmation.
Iguanodon
has become a taxonomic dumping ground for assorted iguanodontians and is in need of revision: most of the British species referred to this genus are almost certainly not closely allied to the neotype species
I. bernissartensis
and require new generic names. Fragmentary remains suggest the early presence of hadrosaurids in Britain. The only British record of Marginocephalia, the Wessex Formation skull roof named
Yaverlandia bitholus
, appears not to belong to this clade but seems to be from a maniraptoran theropod.
The Theory and Interpretation of Electron Energy Loss Near-Edge Fine Structure
Authors: Rez Peter , Muller David A.
Published: April 2008

Electron energy loss fine structure near the threshold of inner-shell edges can potentially give valuable information on bonding on an atomic scale. To use near-edge structure it is essential to understand what factors influence both the occupied and unoccupied local density of states in the material of interest. Different techniques of electronic structure theory are suitable for metals, semiconductors, and ionic materials, although some methods can be applied to a wide range of systems. To extract quantitative information on bonding it is important to avoid those edges that are strongly affected by the presence of the core hole such as cations in ionic materials.
Crystal Chemistry of Complex Perovskites: New Cation-Ordered Dielectric Oxides
Authors: Davies P.K. , Wu H. , Borisevich A.Y. , Molodetsky I.E. , Farber L.
Published: April 2008

The crystal chemistry of complex perovskite dielectric oxides is reviewed, with an emphasis on structures derived from ordering of the cations on the octahedral B-sites. New classes of perovskites, designed to exhibit 1:2 or 1:3 B-site order for application as low-dielectric-loss microwave ceramics, are identified, and their synthesis, structure, and properties are described. Through the use of B-site chemistries based on Li, Nb, Ta, Ti, and W, members of four new families with 1:2 order, A(βI1/3βII2/3)O3, and three new families with 1:3 order, A(βI1/4βII3/4)O3, were successfully prepared. The formation and stability of the new and previously prepared ordered perovskites are rationalized through the use of familiar crystal chemical tools such as cation size and charge difference, bond valence, tolerance factor, and new concepts related to the local charge imbalance on the A- and B-sublattices. These tools can be successfully applied to develop stability field maps for each structure and to predict other new ordered systems.
Nutrition and Mutagenesis
Authors: Ferguson Lynnette R. , Philpott Martin
Published: April 2008

Diet-related mutagenesis plays an etiologic role in chronic diseases, including cardiovascular disease and cancer. Many dietary mutagens are DNA reactive, leading to distinct spectra of base-pair substitution mutations and structural chromosome changes. Examples include aflatoxin B1, ochratoxin A, ptaquiloside, various pyrrolizidine alkaloids, heterocyclic amines including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, and polycyclic aromatic hydrocarbons such as benzo[a]pyrene. However, endogenously or exogenously formed reactive species, inhibitors of topoisomerase II enzymes (e.g., flavonoids), of DNA repair (e.g., caffeine), or of the mitotic spindle (possibly acrylamide), also cause mutations, including structural chromosome changes and copy number variants. Genomic instability also results from inadequate nutrient intake (e.g., folate and selenium). Antimutagens include vitamin C, carotenoids, chlorophyllin, dietary fibers, and plant polyphenols acting through various mechanisms. Polymorphisms in genes for nutrient uptake, metabolism, and excretion will affect dietary intake in determining individual risk of disease development. Human studies utilizing nutrigenomic/nutrigenetic technologies will be essential to quantifying and overcoming diet-related mutagenesis.
Black/White Differences in School Performance: The Oppositional Culture Explanation
Authors: Downey Douglas B.
Published: April 2008

The late anthropologist, John Ogbu, developed one of the most theoretically provocative explanations for racial/ethnic differences in school performance: oppositional culture theory. Rather than view racial/ethnic gaps as a product of structural disadvantage alone, the theory emphasizes minority groups’ agency and the way in which they contribute to their own demise by developing a culture in opposition to schooling. This review focuses on the theory's merits for understanding the black/white gap in the United States.
Sieve, Incubator, Temple, Hub: Empirical and Theoretical Advances in the Sociology of Higher Education
Authors: Stevens Mitchell L. , Armstrong Elizabeth A. , Arum Richard
Published: April 2008

Higher education lacks an intellectually coherent sociology; varied research on colleges and universities is dispersed widely throughout the discipline. This review initiates a critical integration of this scholarship. We argue that sociologists have conceived of higher education systems as sieves for sorting and stratifying populations, incubators for the development of competent social actors, temples for the legitimation of official knowledge, and hubs connecting multiple institutional domains. Bringing these lines of scholarship together facilitates new theoretical insights and research questions.
After Secularization?
Authors: Gorski Philip S. , Altınordu Ateş
Published: April 2008

The study of secularization appears to be entering a new phase. Supply-side theories that focus exclusively on religious participation and membership seem too one-dimensional. But classical theories of secularization contain generalized and teleological premises that are at odds with the complexities of empirical reality and the historical record. This review seeks to map a new way forward and identify key obstacles and goals. It begins by retracing the development of secularization theory within sociology and the genealogy of the secularization concept within presociological discourse. It then reviews what is and is not known about secularization in the West, noting the limitations of the data and biases in research. The article further argues for comparative and historical approaches that incorporate non-Christian religions and non-Western regions. The social scientific literature that critically reassesses the relationship between diverse religious movements, secularisms, and liberal democracies presents new questions for future research. We stress the importance of theoretical approaches that move beyond the deeply entrenched secularist and religious assumptions and propose general guidelines for future research on the varieties of secularity.