bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon addition alters vegetation composition on ex‐arable fields
Authors: ESCHEN RENÉ , MORTIMER SIMON R. , LAWSON CLARE S. , EDWARDS ANDREW R. , BROOK ALEX J. , IGUAL JOSÉ M. , HEDLUND KATARINA , SCHAFFNER URS 
Published: November 2006

Summary

Recent changes in European agricultural policy have led to measures to reverse the loss of species‐rich grasslands through the creation of new areas on ex‐arable land. Ex‐arable soils are often characterized by high inorganic nitrogen (N) levels, which lead to the rapid establishment of annual and fast‐growing perennial species during the initial phase of habitat creation. The addition of carbon (C) to the soil has been suggested as a countermeasure to reduce plant‐available N and alter competitive interactions among plant species.
To test the effect of C addition on habitat creation on ex‐arable land, an experiment was set up on two recently abandoned fields in Switzerland and on two 6‐year‐old restoration sites in the UK. Carbon was added as a mixture of either sugar and sawdust or wood chips and sawdust during a period of 2 years. The effects of C addition on soil parameters and vegetation composition were assessed during the period of C additions and 1 year thereafter.
Soil nitrate concentrations were reduced at all sites within weeks of the first C addition, and remained low until cessation of the C additions. The overall effect of C addition on vegetation was a reduction in above‐ground biomass and cover. At the Swiss sites, the addition of sugar and sawdust led to a relative increase in legume and forb cover and to a decrease in grass cover. The soil N availability, composition of soil micro‐organisms and vegetation characteristics continued to be affected after cessation of C additions.
Synthesis and applications. The results suggest that C addition in grassland restoration is a useful management method to reduce N availability on ex‐arable land. Carbon addition alters the vegetation composition by creating gaps in the vegetation that facilitates the establishment of late‐seral plant species, and is most effective when started immediately after the abandonment of arable fields and applied over several years.
Who benefits from learning with 3D models? the case of spatial ability
Authors: Huk T. 
Published: November 2006

AbstractEmpirical studies that focus on the impact of three‐dimensional (3D) visualizations on learning are to date rare and inconsistent. According to the ability‐as‐enhancer hypothesis, high spatial ability learners should benefit particularly as they have enough cognitive capacity left for mental model construction. In contrast, the ability‐as‐compensator hypothesis proposes that low spatial ability learners should gain particular benefit from explicit graphical representations as they have difficulty mentally constructing their own visualizations. This study examines the impact that interactive 3D models implemented within a hypermedia‐learning environment have on understanding of cell biology. Test scores in a subsequent knowledge acquisition test demonstrated a significant interaction term between students' spatial ability and presence/absence of 3D models. Only students with high spatial ability benefited from the presence of 3D models, while low spatial ability students got fewer points when learning this way. When using 3D models, high spatial ability students perceived their cognitive load to be low whereas the opposite was true for low spatial ability students. The data suggest that students with low spatial ability became cognitively overloaded by the presence of 3D models, while high spatial ability students benefited from them as their total cognitive load remained within working memory limits.
Design of a delegable SCORM conformant learning management system
Authors: Lu E.J.‐L. , Chen Y.‐H. 
Published: November 2006

AbstractOwing to the emergence and flourishing of the Internet, traditional teaching and educational activities are increasingly relying on the convenient and global‐reaching networking technology. To boost up the development of e‐learning technology and the interoperability of learning materials, the Advanced Distributed Learning Initiative defined a data‐sharing standard, called the Sharable Content Object Reference Model (SCORM). In SCORM, because all learning materials (either SCOs or assets) are sharable, users cannot share (or delegate) parts or all of their teaching materials at will. This paper proposed an access control and delegation model for SCORM conformant learning management systems. Also, a prototype was developed to demonstrate the feasibility of the proposed model.
Learning to be a psychologist: the construction of identity in an online forum
Authors: Perrotta C. 
Published: November 2006

AbstractThe paper reports a study that investigated the construction of a common identity in an online Italian forum of psychologists based on asynchronous CMC. Discourse analysis was carried out on 20 discussions, and three Interpretative Repertoires were identified: (i) Professional Boundaries, (ii) disempowered psychology and (iii) psychology and health, which refer to three recurrent modalities of constructing the psychological profession. The study suggests that a framework drawing on social constructionism and Bourdieu's critical theory can help understand some aspects of identity in, and across, communities of practice. The main conclusion is that analysing critically how identities are constructed in learning environments, virtual or not, allows reconsidering the role of the cultural context in the production of those identities.
The role of rainfall and predators in determining synchrony in reproduction of savanna trees in Serengeti National Park, Tanzania
Authors: MDUMA SIMON A. R. , SINCLAIR A. R. E. , TURKINGTON ROY 
Published: November 2006

Summary

We examined the factors determining synchrony in reproduction in nine Acacia and six other tree species in the Serengeti ecosystem.
We test two hypotheses: (i) an abiotic hypothesis where the primary determinant of synchrony is an adaptation to water availability; and (ii) biotic hypotheses where these adaptations to water can be further refined by additional adaptations to avoid predators, or attract seed and fruit dispersers.
Flowering and fruiting were recorded monthly for individually marked trees during 1997–2004. Flowering in different species occurs semi‐annually, annually or, in the case of one species, once every 2 years. For most species synchrony of flowering was correlated with seasonal rainfall, with lags related to the mean height of the species; small species flowered during the rains while larger species flowered in the dry season. Fruiting seasons occurred at the end of the rains irrespective of the flowering season.
Most species showed flowering synchrony greater than expected from the distribution of rainfall. This may be related to avoidance of insect seed predators through predator satiation. Two Acacias showed multi‐annual fruiting (masting), possibly as a predator avoidance mechanism. Acacia tortilis has two flowering seasons: a dry season flowering with early abortion of pods and a wet season flowering producing successful fruits.
Two species of Commiphora appeared to be synchronized so as to attract birds that disperse seeds. Acacia tortilis produced indehiscent pods attractive to ungulates, possibly to kill bruchid beetles during digestion and so increase seed viability.
Our results suggest that synchrony in these trees is caused by a strong interaction between abiotic and biotic factors. Closely related species have different reproductive patterns of synchrony that seem to be adapted to different combinations of rainfall, predators and dispersers. Rainfall is the primary determinant but the activities of predators and dispersers increase the degree of synchrony.
Socio‐economic position, household composition, health status and indicators of the well‐being of mothers of children with and without intellectual disabilities
Authors: Emerson E. , Hatton C. , Llewellyn G. , Blacker J. , Graham H. 
Published: November 2006

AbstractBackground  Many previous studies have reported that mothers of children with intellectual disabilities (IDs) are more likely to show signs of psychological distress and have lower well‐being than mothers of ‘typically developing’ children. Our aim was to estimate the extent to which these differences may be accounted for by between‐group differences in socio‐economic position.Methods  This study involved secondary analysis of happiness, self‐esteem and self‐efficacy variables in a nationally representative sample of 6954 British mothers with dependent children under the age of 17 years, 514 of whom were supporting a child with an ID.Results  Mothers of children with IDs reported lower levels of happiness, self‐esteem and self‐efficacy than mothers of children without IDs. Statistically controlling for differences in socio‐economic position, household composition and maternal characteristics fully accounted for the between‐group differences in maternal happiness, and accounted for over 50% of the elevated risk for poorer self‐esteem and self‐efficacy.Conclusions  A socially and statistically significant proportion of the increased risk of poorer well‐being among mothers of children with IDs may be attributed to their increased risk of socio‐economic disadvantage.
A sequence stratigraphic model for an intensely bioturbated shallow‐marine sandstone: the Bridport Sand Formation, Wessex Basin, UK
Authors: MORRIS JENNY E. , HAMPSON GARY J. , JOHNSON HOWARD D. 
Published: November 2006

AbstractThe Bridport Sand Formation is an intensely bioturbated sandstone that represents part of a mixed siliciclastic‐carbonate shallow‐marine depositional system. At outcrop and in subsurface cores, conventional facies analysis was combined with ichnofabric analysis to identify facies successions bounded by a hierarchy of key stratigraphic surfaces. The geometry of these surfaces and the lateral relationships between the facies successions that they bound have been constrained locally using 3D seismic data. Facies analysis suggests that the Bridport Sand Formation represents progradation of a low‐energy, siliciclastic shoreface dominated by storm‐event beds reworked by bioturbation. The shoreface sandstones form the upper part of a thick (up to 200 m), steep (2–3°), mud‐dominated slope that extends into the underlying Down Cliff Clay. Clinoform surfaces representing the shoreface‐slope system are grouped into progradational sets. Each set contains clinoform surfaces arranged in a downstepping, offlapping manner that indicates forced‐regressive progradation, which was punctuated by flooding surfaces that are expressed in core and well‐log data. In proximal locations, progradational shoreface sandstones (corresponding to a clinoform set) are truncated by conglomerate lags containing clasts of bored, reworked shoreface sandstones, which are interpreted as marking sequence boundaries. In medial locations, progradational clinoform sets are overlain across an erosion surface by thin (<5 m) bioclastic limestones that record siliciclastic‐sediment starvation during transgression. Near the basin margins, these limestones are locally thick (>10 m) and overlie conglomerate lags at sequence boundaries. Sequence boundaries are thus interpreted as being amalgamated with overlying transgressive surfaces, to form composite erosion surfaces. In distal locations, oolitic ironstones that formed under conditions of extended physical reworking overlie composite sequence boundaries and transgressive surfaces. Over most of the Wessex Basin, clinoform sets (corresponding to high‐frequency sequences) are laterally offset, thus defining a low‐frequency sequence architecture characterized by high net siliciclastic sediment input and low net accommodation. Aggradational stacking of high‐frequency sequences occurs in fault‐bounded depocentres which had higher rates of localized tectonic subsidence.
Development of spatially diverse and complex dune‐field patterns: Gran Desierto Dune Field, Sonora, Mexico
Authors: BEVERIDGE CARRIE , KOCUREK GARY , EWING RYAN C. , LANCASTER NICHOLAS , MORTHEKAI P. , SINGHVI ASHOK K. , MAHAN SHANNON A. 
Published: November 2006

AbstractThe pattern of dunes within the Gran Desierto of Sonora, Mexico, is both spatially diverse and complex. Identification of the pattern components from remote‐sensing images, combined with statistical analysis of their measured parameters demonstrate that the composite pattern consists of separate populations of simple dune patterns. Age‐bracketing by optically stimulated luminescence (OSL) indicates that the simple patterns represent relatively short‐lived aeolian constructional events since ∼25 ka. The simple dune patterns consist of: (i) late Pleistocene relict linear dunes; (ii) degraded crescentic dunes formed at ∼12 ka; (iii) early Holocene western crescentic dunes; (iv) eastern crescentic dunes emplaced at ∼7 ka; and (v) star dunes formed during the last 3 ka. Recognition of the simple patterns and their ages allows for the geomorphic backstripping of the composite pattern. Palaeowind reconstructions, based upon the rule of gross bedform‐normal transport, are largely in agreement with regional proxy data. The sediment state over time for the Gran Desierto is one in which the sediment supply for aeolian constructional events is derived from previously stored sediment (Ancestral Colorado River sediment), and contemporaneous influx from the lower Colorado River valley and coastal influx from the Bahia del Adair inlet. Aeolian constructional events are triggered by climatic shifts to greater aridity, changes in the wind regime, and the development of a sediment supply. The rate of geomorphic change within the Gran Desierto is significantly greater than the rate of subsidence and burial of the accumulation surface upon which it rests.
Cathodoluminescence characterization of quartz particles in mature arenites
Authors: GÖTTE THOMAS , RICHTER DETLEV K. 
Published: November 2006

AbstractA combination of cathodoluminescence (CL) microscopy with digital image analysis and spectroscopic analysis allows the detailed investigation of the commonly occurring colour shift from initial to final CL‐colours in detrital quartz with increasing irradiation. A method for the quantification of the colour shift is presented and applied to different quartz sands: unlithified sands of the Lower Cretaceous Kuhfeld Formation from Ottenstein (W Germany) and Holocene sands from the barrier island of Wangerooge (N Germany). The colour shift depends on the defect structure of the quartz grains. The defect structure is determined by the physico‐chemical conditions during crystallization and therefore can help trace the source of quartz grains. A total of 25 different types of quartz grains in the Ottenstein‐sands indicates a highly variable southern provenance. Many of the grains have recycled quartz cement overgrowths indicating an at least second cycle origin. In contrast, only 16 different quartz types have been observed in the Wangerooge‐sands reflecting a less varied plutonic to metamorphic Scandinavian provenance. The study demonstrates the potential of quantified CL initial colour and colour shift in assessing the provenance of quartz‐rich sands and sandstones.
Short‐term morphological change and sediment dynamics in the intertidal zone of a macrotidal beach
Authors: MASSELINK GERHARD , AUGER NIGEL , RUSSELL PAUL , O'HARE TIM 
Published: November 2006

AbstractThis paper describes the morphological and sedimentological evolution of a macrotidal beach over a 20 day period under varying hydrodynamic conditions (significant breaker heights of 0·3–2 m and tidal ranges of 2–5 m). During the field campaign, an intertidal bar developed around the mid‐tide level, migrated onshore, welded to the upper beach and was then flattened under energetic wave conditions. The bar had a wave breakpoint origin and its formation was triggered by a reduction in tidal range, causing more stationary water‐level conditions, rather than an increase in wave height. Most of the onshore bar migration took place while the bar was positioned in the inner to mid‐surf zone position, such that the bar moved away from the breakpoint and exhibited ‘divergent’ behaviour. The depth of disturbance over individual tidal cycles was 10–20% of the breaker height. Such values are more typical of steep reflective beaches, than gently sloping, dissipative beaches, and are considered to reflect the maximum height of wave‐generated ripples. The grain size distribution of surficial sediments did not vary consistently across the beach profile and temporal changes in the sedimentology were mostly unrelated to the morphological response. The lack of clear links between beach morphology and sedimentology may be in part due to shortcomings in the sampling methodology, which ignored the vertical variability in the sediment size characteristics across the active layer.
Production and characterization of murine monoclonal antibodies against human podocalyxin
Authors: Rodríguez R. B. , Butta N. , Larrucea S. , Alonso S. , Parrilla R. 
Published: November 2006

AbstractPodocalyxin (podxl) is a protein with a peptide bone of ∼55.5 kDa that undergoes a post‐translational glycosylation, yielding a final molecular mass from ∼145 to ∼200 kDa. This protein is normally found covering the vascular side of the epithelial glomerular cells, the podocytes, and its presence is essential to maintain a normal renal function. It has also been reported in other cells and tissues although its function has not been yet clarified. The carboxy‐terminal intracellular domain of podxl is nearly 100% identical in most species; however, the ectodomain shows considerable variations although the cysteine residues are conserved. Detection of this protein is elusive, most likely due to differences in post‐translational modifications. We aimed at producing murine monoclonal antibodies against human podxl. Immunization with Chinese hamster ovarian ‐hpodxl‐green fluorescence protein live cells yielded five different monoclonal antibodies that were characterized by enzyme‐linked immunosorbent assay, sodium dodecyl sulfate–polyacrylamide gel electrophoresis/western blot, flow cytometry, immunohistochemistry, and immunoprecipitation. The different behavior of these antibodies suggests that some of them may react against epitopes masked by different glycosylated protein moieties.
Digestibility and nitrogen retention of diets containing different levels of fibre in local (Mong Cai), F1 (Mong Cai × Yorkshire) and exotic (Landrace × Yorkshire) growing pigs in Vietnam
Authors: Len N. T. , Lindberg J. E. , Ogle B. 
Published: November 2006

SummaryTotal tract digestibility and nitrogen retention of three diets containing different levels of fibre [200, 260 and 320 g/kg neutral detergent fibre (NDF) in dry matter] were determined in three breeds of growing pig at an initial age of approximately 3.5 months. The breeds were local (Mong Cai, MC), F1 crossbred (MC × Yorkshire) and exotic (Landrace × Yorkshire, LY), allocated at random within breed (block) to double 3 × 3 Latin squares. The main fibrous ingredients of the experimental diets were rice bran, cassava residue meal and non‐dehulled groundnut cake meal. Digestibility of organic matter (OM), crude protein (CP), NDF, crude fibre, gross energy (GE) and ether extract (EE) decreased as the level of dietary NDF increased (p < 0.001). The r2 values for the relationship between NDF level and digestibility of OM, CP, GE and EE were 83%, 83%, 80% and 82% respectively. On average, an increase in NDF content of 1% unit resulted in a decrease in OM, CP, GE and EE digestibility of 0.67%, 0.75%, 0.50% and 0.42% units respectively. Digestibility of energy and nutrients was the highest for MC and the lowest for LY (p < 0.01), with intermediate values for F1. There was a negative effect of NDF level on nitrogen (N) retained as a proportion of intake (p < 0.05). Nitrogen retention and utilization were significantly higher (p < 0.001) for LY than for MC and F1 pigs.
Influence of different phosphorus levels and phytase supplementation in gestation diets on sow performance
Authors: Lyberg K. , Andersson H. K. , Simonsson A. , Lindberg J. E. 
Published: November 2006

SummaryA total of 104 sows of different parities were studied. They were fed four diets with different phosphorus (P) levels during gestation for two reproductive cycles, while the same diet was fed during lactation. The aim was to decrease the total P level in the diet during gestation and to evaluate the effect on sow performance. The gestation treatments were low P (LP−; 3.7 g P/kg feed), low P with phytase (LP+, Ronozyme® P; 765 FTU/kg feed), medium P (MP; 4.5 g P/kg feed) and high P (HP; 6.0 g P/kg feed). Daily feed allowances were 2.6 kg during gestation and 9.2 kg during lactation. Number of born piglets and piglet mortality were higher (p < 0.05) in the LP treatments than in the MP and HP treatments. No difference (p > 0.05) in the numbers of live‐born piglets, piglet birthweights, sow weights or piglet weight gains was found between the treatments. Phosphorus level in sow milk was the highest (p < 0.05) in the MP treatment, while no effects (p > 0.05) of treatment were found on milk Ca levels, P and Ca levels in serum of sows and piglets, nor on the analysed mineral, fat and protein contents of piglets. The estimated average requirement of P for the entire gestation period was 4.4–4.5 g/day. In conclusion, a reduction of dietary total P content during gestation did not result in negative effects on sow or piglet performance. This suggests that it should be possible to lower the dietary P content for gestating sows, compared with earlier recommendations, and thereby reduce the environmental P pollution.
Synchronous intercontinental splits between assemblages of woodpeckers suggested by molecular data
Authors: Fuchs Jérôme , Ohlson Jan I. , Ericson Per G. P. , Pasquet Eric 
Published: November 2006

The woodpeckers (Piciformes: Picinae) comprise a widely distributed and species‐rich clade of birds that is strongly associated with trees for feeding, nesting, or both. Because of this association, woodpeckers provide a useful model for evaluating the impact of climatic and tectonic events on the diversification of forest birds during the Tertiary. In order to resolve the biogeographical history of the woodpeckers, we have analysed sequences from two nuclear introns and one mitochondrial gene using likelihood and Bayesian approaches. Our analyses favour a tropical Eurasian origin; divergences between African, Indo‐Malayan and New World clades with subsequent colonizations of Africa and the New World occurred synchronously during the Middle Miocene, a period corresponding to the expansion of the C4 grasses and the uplift of the Himalayan‐Tibetan plateau. The taxonomic diversification of woodpeckers at this time may be attributed to the fragmentation of forests in response to the drier climate, which in turn prevented gene flow between tropical stocks in Africa, Indo‐Malaya and the New World. Our estimates of colonization times of South America predate the closure of the Panama Isthmus and support the hypothesis of a short‐lived, terrestrial corridor at the end of the Miocene, 5.7 Myr BP.