bluuebunny/crossref_metadata_2025 huggingface dataset:
Hippocampal hyperexcitability and specific epileptiform activity in a mouse model of Dravet syndrome
Authors: Liautard Camille , Scalmani Paolo , Carriero Giovanni , de Curtis Marco , Franceschetti Silvana , Mantegazza Massimo
Published: May 2013

Purpose

Dravet syndrome (DS) is caused by dominant mutations of the SCN1A gene, encoding the NaV1.1 sodium channel α subunit. Gene targeted mouse models of DS mutations replicate patients' phenotype and show reduced γ‐aminobutyric acid (GABA)ergic inhibition. However, little is known on the properties of network hyperexcitability and on properties of seizure generation in these models. In fact, seizures have been studied thus far with surface electroencephalography (EEG), which did not show if specific brain regions are particularly involved. We have investigated hyperexcitability and epileptiform activities generated in neuronal networks of a mouse model of DS.

Methods

We have studied heterozygous NaV1.1 knock‐out mice performing field potential recordings in combined hippocampal/cortical slices in vitro and video/depth electrode intracerebral recordings in vivo during hyperthermia‐induced seizures.

Key Findings

In slices, we have disclosed specific signs of hyperexcitability of hippocampal circuits in both the pre‐epileptic and epileptic periods, and a specific epileptiform activity was generated in the hippocampus upon application of the convulsant 4‐aminopyridine in the epileptic period. During in vivo hyperthermia‐induced seizures, we have observed selective hippocampal activity in early preictal phases and pronounced hippocampal activity in the ictal phase.

Significance

We have identified specific epileptiform activities and signs of network hyperexcitability, and disclosed the important role of the hippocampus in seizure generation in this model. These activities may be potentially used as targets for screenings of antiepileptic approaches.
Family Ties in Entrepreneurs’ Social Networks and New Venture Growth
Authors: Arregle Jean–Luc , Batjargal Bat , Hitt Michael A. , Webb Justin W. , Miller Toyah , Tsui Anne S.
Published: May 2013

Family ties are an important conduit of resources for entrepreneurs, but both positive and negative outcomes can arise. Building upon a family embeddedness perspective, we develop hypotheses about curvilinear relationships between the proportion of family ties in entrepreneurs’ networks and venture growth. We test them on entrepreneurs from China, France, Russia, and the United States. These effects appear to be related to the type of entrepreneurs’ social network (business advice, emotional support, and business resources). Our results confirm effects specific to each network: an inverted U–shape for advice and emotional support networks but a U–shape for the business resource network, measuring what proportion of kin in each entrepreneurial network type is valuable to or, conversely, undermines new venture growth.
Structural integrity assessment of metallic components under multiaxial fatigue: the C–S criterion and its evolution
Authors: Carpinteri Andrea , Spagnoli Andrea , Vantadori Sabrina , Bagni Cristian
Published: May 2013

The present paper discusses the evolution of a critical plane‐based multiaxial high‐cycle fatigue criterion, known as Carpinteri–Spagnoli criterion. By proposing appropriate changes to the original formulation, the extended versions of the aforementioned criterion are able to assess smooth and notched metallic structural components subjected to different fatigue loading conditions, such as multiaxial in‐phase and out‐of‐phase synchronous cyclic loading, asynchronous cyclic loading and random loading. The results obtained through this criterion are compared with some experimental results related to relevant data reported in the literature.
Still colonising the Ord River, northern Australia: a postcolonial geography of the spaces between Indigenous people's and settlers' interests
Authors: McLean Jessica
Published: May 2013

The growing use of environmental flows in rivers and wetlands around the world, aimed at maintaining ecological health by allocating water to the environment, arguably also provides space for recognition of Indigenous water values. Theoretically, if environmental water values, which nominally determine what water is made available for restoring river health through environmental flows, do coincide with Indigenous water values, then this mutual benefit is conceivable. However, in contexts such as the Ord in northern Australia, where environmental water values are defined as post‐dam construction, then further marginalisation of Indigenous interests likely ensues. This paper looks at the history of two key industries in the Ord, pastoralism and irrigation, to examine the origins of its current geography of environmental water values. A geography of water emerges that unpacks postcolonial relations as manifest in society–water relations. I examine how particular colonial values that reinforce the status quo of industry in the Ord also dominate water management, effectively sidelining Indigenous water values.
Diffuse lung disease in infancy and childhood: expanding the chILD classification
Authors: Rice Alexandra , Tran‐Dang My‐Anh , Bush Andrew , Nicholson Andrew G
Published: May 2013

Aims

Diffuse parenchymal lung diseases (DPLD) in children comprise a wide spectrum of rare disorders. In 2007 the Children's Interstitial Lung Disease (chILD) Research Cooperative proposed a classification system for DPLD in children <2 years of age. The aims of our study were to determine the utility and reproducibility of this system in children <2 years of age, and test its extension to 18 years of age.

Methods and results

Of 211 cases, 93 were <2 years of age at presentation and 58% were included in the chILD classification. In 118 cases aged between 2 and 18 years there was a wider distribution of disorders, overlapping with those seen in adults, necessitating expansion of the chILD classification types to encompass all reviewed cases, in particular patients with ‘adult’ diffuse lung diseases. Many cases showed mixed histological patterns, overlap often being between groups of disorders more prevalent in infancy. Concordance between reporting pathologists was 90%.

Conclusions

The chILD scheme allows classification of conditions more common in children <2 years of age. It can be applied to children of any age, although additional entities need to be included. We propose a more histologically based system for use when assessing biopsies in this context.
Member engagement within digitally enabled social network communities: new methodological considerations
Authors: Germonprez Matt , Hovorka Dirk S.
Published: May 2013

Digitally enabled social networks (DESN) are a complex assemblage of engagement, reflection, action, technology, organization and community. DESN create a unique challenge for researchers who aim to understand what social networks are, what they can become and what enablers and constraints underlie trajectories of member engagement. As DESN continually evolve, knowing them as stable and reified representations or as mere technology artefacts provides a limited understanding of their complexity and emergent properties. While DESN are, in part, the technology that supports the necessary actions for engagement, they are also the people and behaviours that constitute its community. Through the presentation of new methodological considerations towards Digg, a large DESN, we observe that social networks entail practices of engagement, change and evolution within a DESN community. We reveal how engagement is a communal endeavour and that the clash of socio‐technical trajectories can result in the emergence of new paths of member participation. Our findings demonstrate the potential of netnography and impressionist tales for contributing to the ongoing pluralistic investigations of DESN and also inform research on engagement and community design and change.
Endemic plant communities on special soils: early victims or hardy survivors of climate change?
Authors: Damschen Ellen I. , Harrison Susan , Ackerly David D. , Fernandez‐Going Barbara M. , Anacker Brian L.
Published: May 2013

1. Predicting and mitigating climate change effects on ecological communities is a tremendous challenge. Little attention has been given to how endemic‐rich communities on isolated patches of low‐nutrient soil (e.g. serpentine) will respond to climate change.

2. To address spatial factors (the isolated nature of outcrops), we incorporate habitat patchiness into species distribution models under climate change. The degree of overlap between current and future suitable habitat does not change when patchy habitats are incorporated, probably because serpentine occurs in mountainous regions where climatically and edaphically suitable regions geographically coincide. The dispersal distances required to move to newly suitable habitat are large, however, making successful migration unlikely.

3. To address how non‐spatial factors affect the climate change responses of serpentine plant communities (e.g. the impacts of nutrient limitation and stress‐tolerant functional traits), we conduct a literature review. Some studies suggest that serpentine communities may be at less risk than ‘normal’ soil communities due to their stress‐tolerant functional traits, but there is also evidence to the contrary.

4. Synthesis. Assessing climate change risk for the world’s diverse edaphic floras requires determining impacts on both special and ‘normal’ soil communities. Studies are needed that use functional traits, evaluate the role of evolutionary and ecological plasticity, examine responses across spatial and temporal scales and assess the efficacy of managed relocation efforts.
Resource‐based habitat associations in a neotropical liana community
Authors: Dalling James W. , Schnitzer Stefan A. , Baldeck Claire , Harms Kyle E. , John Robert , Mangan Scott A. , Lobo Elena , Yavitt Joseph B. , Hubbell Stephen P.
Published: May 2013

1. Lianas are a conspicuous element of many tropical forests, accounting for up to 40% of woody stem density and 20% of species richness in seasonal forests. However, lianas have seldom been surveyed at sufficiently large spatial scales to allow an assessment of the importance of habitat variables in structuring liana communities.

2. We compare the association patterns of 82 liana species and an equivalent sample of tree species on the 50 ha Forest Dynamics Project plot on Barro Colorado Island, Panama, with topographic habitat variables (high and low plateau, slope, swamp and streamside), and thirteen mapped soil chemical variables. In addition, we test for liana species associations with canopy disturbance using a canopy height map of the plot generated using light detection and ranging.

3. For all liana species combined, densities differed among topographic habitat types in the plot, with significantly higher densities on the seasonally drier lower plateau habitat (1044 individuals ha−1) than the moister slope habitat (729 individuals ha−1). Lianas were also significantly more abundant than expected in areas with low canopy height.

4. The proportion of liana species associated with one or more topographic habitat variables (44%) was significantly lower than that for trees (66%). Similarly, liana species were significantly less frequently associated with PC axes derived from soil chemical variables (21%) than trees (52%). The majority of liana species (63%) were significantly associated with areas of the plot with low canopy height reflecting an affinity for treefall gaps.

5. Synthesis. The habitat associations detected here suggest that liana density is associated primarily with canopy disturbance, and to a lesser extent with topography and soil chemistry. Relative to trees, few liana species were associated with local variation in topography and soil chemistry, suggesting that nutrient availability exerts only weak effects on liana community composition compared to trees. Results from this study support the contention that increases in forest disturbance rates are a driver of recently observed increases in liana abundance and biomass in neotropical forests.
Continental‐scale variability in browser diversity is a major driver of diversity patterns in acacias across Africa
Authors: Greve Michelle , Lykke Anne M. , Fagg Christopher W. , Bogaert Jan , Friis Ib , Marchant Rob , Marshall Andrew R. , Ndayishimiye Joël , Sandel Brody S. , Sandom Christopher , Schmidt Marco , Timberlake Jonathan R. , Wieringa Jan J. , Zizka Georg , Svenning Jens‐Christian
Published: May 2013

1. It has been proposed that, across broad spatial scales, climatic factors are the main drivers of ecological patterns, while biotic factors are mainly important at local spatial scales. However, few tests of the effect of biotic interactions on broad‐scale patterns have been conducted; conclusions about the scale‐dependence of the importance of biotic interactions thus seem premature.

2. We developed an extensive database of locality records of one of Africa’s most conspicuous groups, the acacias (the genera Senegalia and Vachellia), and used species distribution models (SDMs) to estimate the distribution of all African acacias.

3. African acacias are particularly well adapted against mammalian herbivory; therefore, we hypothesized that browser diversity could be an important driver of acacia richness. Species richness maps for the two genera were created from SDM‐generated maps. Ordinary least square (OLS) regressions and, to consider spatial autocorrelation, simultaneous autoregressive (SAR) analyses were used to model richness of the two genera in relation to mammalian browser richness, current environment (including climate), and climate history since the Last Glacial Maximum (LGM). We used variation partitioning to determine what percentage of variation could be explained by these three groups of factors.

4. Both genera showed centres of richness in East Africa and the Limpopo Basin of southern Africa. Browser richness was the best explanatory variable for richness of both genera. Environmental factors explained negligible variation in the richness of Senegalia, but some variation in Vachellia. For both genera, the residuals of the species richness model of one genus also explained much variation in the richness of the other genus, indicating that common factors not considered in the richness analyses here may additionally be driving the richness of both genera.

5. Mechanisms that could generate a correlation between browser and acacia richness are proposed, and differences in the determinants of richness patterns of Senegalia and Vachellia discussed in the light of the two genera’s history of colonization of Africa.

6. Synthesis. This is the first study that demonstrates that consumer diversity can influence richness patterns at continental scales and demonstrates that biotic factors can drive richness even at broad spatial scales.
Spatial contiguity and continuity of canopy gaps in mixed wood boreal forests: persistence, expansion, shrinkage and displacement
Authors: Vepakomma Udayalakshmi , Kneeshaw Daniel , Fortin Marie‐Josée
Published: May 2013

1. Variation in forest gap size and duration are a result of spatial contiguity and continuity of gap infilling and tree mortality over time, which influences both species recruitment and successional pathways.

2. As many gaps in boreal forests are small, their size and duration will affect the conditions influencing species recruitment. We investigate the spatial dynamics of these gaps (i.e. those which are persistent, ephemeral, expanding, displaced or disappearing) and tested whether gap spatio‐temporal patterns are consistent over different temporal periods (1998–2003 and 2003–2007).

3. Forest canopy gaps were reconstructed for three plots (10, 10 and 6 ha in size) in southern boreal mixedwood forests around Lake Duparquet, north‐western Quebec (Canada), using a time series of high‐resolution canopy surface profiles from three light and ranging detection (lidar) system surveys during a 9‐year window. High‐resolution images were used to individually identify early and late successional gap makers. Dynamic changes in canopy gaps over a 9‐year period were investigated by implementing concepts of random set theory within a temporal GIS framework. Mortality was higher on the gap edges than in the forest interior, and shade tolerant species were more likely to be gap makers than shade intolerant species. Edge trees that died causing the expansion of gaps were much smaller than trees creating new gaps. Although the overall gap size distribution was consistent over the 9 years studied, the proportion of the total area opening and closing varied between periods. Independent analyses of time windows show an abundance of small gaps (below 40 m2) appearing and disappearing; however, analysis of spatial contiguity shows that the majority (over 80%) of gaps of all sizes were displaced and/or expanded.

4. Synthesis. Contrary to the previous perception that small gaps are ephemeral, which would favour the recruitment of late successional species, our findings indicate that gap displacement and expansion may be a mechanism explaining the maintenance of favourable conditions for the recruitment of shade intolerant individuals, which has been previously observed in high‐latitude old‐growth boreal forests.
Evolution of dispersal traits in a biogeographical context: a study using the heterocarpicRumex bucephalophorusas a model
Authors: Talavera María , Arista Montserrat , Ortiz Pedro L.
Published: May 2013

1.Seed dispersal is crucial in determining the spatial patterns of plant populations, and selection pressure for dispersal varies over different scales. However, few empirical studies have assessed differences in dispersal traits in a biogeographical context.

2.We studied dispersal traits in 46 populations ofRumex bucephalophorusfrom mainland and island locations, and from different habitats to test predictions of how insularity and habitat characteristics affect both dispersability (dispersal capacity and number of dispersible diaspores) and dispersal‐distance strategy. We also conducted a greenhouse experiment to compare dispersability of plants in nature and a controlled environment.

3.Dispersability drastically changed when plants were cultivated in the greenhouse, revealing a high phenotypic plasticity for dispersal and showing that the maternal environment directly influences dispersal. However, dispersal‐distance strategy, estimated by the production of either long diaspores (LD) or short diaspores (SD), seems to be genetically determined. Dispersability was markedly affected by the habitat in which the plants develop, but the patterns found are not consistent with theoretical predictions. We found two contrasting patterns of dispersal on islands: Atlantic island populations showed a trend to seed monomorphism and mid‐dispersal strategy, whilst Mediterranean island populations showed seed heteromorphism and long‐dispersal strategy. These contrasting patterns support theoretical predictions that long‐distance dispersal evolves in heteromorphic plants, whilst in monomorphic plants only local dispersal evolves. Lastly, we have found a clear mid‐dispersal‐distance strategy in coastal sands and Atlantic islands; we suggest that the low environmental variation shared by these two zones selects for shorter distances of dispersal.

4.Synthesis. Most models describing the evolution of dispersal strategies assume that forces selecting for decreased dispersability also select for decreased dispersal distances. However, inR. bucephalophorusdispersal distance and dispersability showed contrasting patterns of variation. The fact that these two traits are differently determined could suggest that they can respond in a different manner to selective pressures.
Differences between symmetric and asymmetric facilitation matter: exploring the interplay between modes of positive and negative plant interactions
Authors: Lin Yue , Berger Uta , Grimm Volker , Ji Qian‐Ru
Published: May 2013

Facilitation (positive interaction) has received increasing attention in plant ecology over the last decade. Just as for competition, distinguishing different modes of facilitation (mutualistic, commensal or even antagonistic) may be crucial.

We therefore introduce the new concept of symmetric versus asymmetric facilitation and present a generic individual‐based zone‐of‐influence model. The model simultaneously implements different modes of both facilitation and competition among individual plants via their overlapping zone of influence. Because we consider facilitation modes as a continuum related to environmental context, we integrated this concept with the stress‐gradient hypothesis (SGH) by exploring differences in spatial pattern formation in self‐thinning plants along a stress gradient in our model.

The interplay among modes of interaction creates distinctly varied spatial patterns along stress gradients. When competition was symmetric, symmetric facilitation (mutualism) consistently led to plant aggregation along stress gradients. However, asymmetric facilitation (commensalism) produces plant aggregation only under more benign conditions but tends to intensify local competition and spatial segregation when conditions are harsh. When competition was completely asymmetric, different modes of facilitation contributed little to spatial aggregation.

Symmetric facilitation significantly increased survival at the severe end of the stress gradient, which supports the claim of the SGH that facilitation should have generally positive net effects on plants under high stress levels. Asymmetric facilitation, however, was found to increase survival only under intermediate stress conditions, which contradicts the current predictions of the SGH.

Synthesis. Our modelling study demonstrates that the interplay between modes of facilitation and competition affects different aspects of plant populations and communities, implying context‐dependent outcomes and consequences. The explicit consideration of the modes and mechanisms of interactions (both facilitation and competition) and the nature of stress factors will help to extend the framework of the SGH and foster research on facilitation in plant ecology.
Direct and productivity‐mediated indirect effects of fertilization, mowing and grazing on grassland species richness
Authors: Socher Stephanie A. , Prati Daniel , Boch Steffen , Müller Jörg , Klaus Valentin H. , Hölzel Norbert , Fischer Markus
Published: May 2013

Recent declines in biodiversity have given new urgency to questions about the relationship between land‐use change, biodiversity and ecosystem processes. Despite the existence of a large body of research on the effects of land use on species richness, it is unclear whether the effects of land use on species richness are principally direct or indirect, mediated by concomitant changes in ecosystem processes. Therefore, we compared the direct effects of land use (fertilization, mowing and grazing) on species richness with indirect ones (mediated via grassland productivity) for grasslands in central Europe.

We measured the richness and above‐ground biomass in 150 grassland plots in 3 regions of Germany (the so‐called Biodiversity Exploratories). We used univariate and structural equation models to examine direct and indirect land‐use effects.

The direct effects of mowing (−0.37, effect size) and grazing (0.04) intensity on species richness were stronger compared with the indirect effects of mowing (−0.04) and grazing (−0.01). However, the strong negative effect of fertilization (−0.23) on species richness was mainly indirect, mediated by increased productivity compared with the weak direct negative effect (−0.07).

Differences between regions in land‐use effects showed five times weaker negative effects of mowing (−0.13) in the region with organic soils (Schorfheide‐Chorin), strong overall negative effects of grazing (−0.29) for the region with organic soils opposed to a similar strong positive effect (0.30) in the Hainich‐Dün region, whereas the Schwäbische Alb region displayed a five times weaker positive effect (0.06) only. Further, fertilization effects on species richness were positive (0.03) for the region with organic soils compared to up to 25 times stronger negative effects in the other two regions.

Synthesis. Our results clearly show the importance of studying both direct and indirect effects of land‐use intensity. They demonstrate the indirect nature, via productivity, of the negative effect of fertilization intensity on plant species richness in the real‐world context of management‐induced gradients of intensity of fertilization, mowing and grazing. Finally, they highlight that careful consideration of regional environments is necessary before attempting to generalize land‐use effects on species diversity.
Pollination linkage between canopy flowering, bumble bee abundance and seed production of understorey plants in a cool temperate forest
Authors: Inari Naoki , Hiura Tsutom , Toda Masanori J. , Kudo Gaku
Published: May 2013

In forest ecosystems, canopy trees provide a large amount of floral resources for pollinators but flower production fluctuates highly from year to year. Temporal variation in floral resources may influence the population dynamics of pollinators.

We investigated the relationship between the population dynamics of bumble bees (Bombus spp.) and canopy floral resources over 5 years in a cool temperate forest. We predicted that the yearly fluctuation of canopy resources affects colony development and queen production, resulting in the variation of the pollination success of understorey plants the following spring.

Flower production of canopy trees showed clear biyearly fluctuations, synchronously among most species. Worker production of Bombus ardens and Bombus hypocrita were positively related to floral resources during colony establishment by overwintered queens, while that of Bombus diversus was positively related to floral resources during the worker‐active period.

An abundance of overwintered queens was positively related to both worker abundance and floral resources in the previous summer in B. ardens and to only previous‐year worker abundance in B. hypocrita but was dependent on neither factor in B. diversus. These differences in causal effects on queen production among species might be a reflection of interspecific differences in the degree of dependence on canopy resources for queen production due to species‐specific phenologies and/or foraging preferences of other species of flowers.

The extent of pollen limitation in the spring‐ephemeral Corydalis ambigua, which is exclusively pollinated by overwintered queens, was negatively correlated with the abundance of B. hypocrita queens. Thus, population dynamics of bumble bees has a crucial effect on seed production of understorey plants.

Synthesis. The dynamics of flower production in overstory trees can indirectly affect the pollination efficiency of understorey plants in the next season via the population dynamics of pollinators. Our results suggest that a cascade effect occurs through pollination networks in a cool temperate forest ecosystem.
Biotic resistance: exclusion of native rodent consumers releases populations of a weak invader
Authors: Pearson Dean E. , Potter Teal , Maron John L.
Published: May 2013

Biotic resistance is a commonly invoked hypothesis to explain why most exotic plant species naturalize at low abundance. Although numerous studies have documented negative impacts of native consumers on exotic plant performance, longer‐term multi‐generation studies are needed to understand how native consumer damage to exotics translates to their population‐level suppression over large landscapes.

We used rodent exclosures and embedded seed‐addition experiments to evaluate the effects of rodent herbivory and granivory on populations of Tragopogon dubius, a Eurasian aster that typically occurs at low abundance across North America.

Vegetation surveys encompassing 20 000 km2 of west‐central Montana grasslands established that T. dubius is regionally well distributed, occurring in 81% of 16 grasslands sampled. However, it consistently occurred at low local abundance, averaging < 0.5% cover in 1 m2 plots.

In large rodent exclosures, T. dubius attained population densities that averaged over five times higher than in paired rodent‐access control plots at 11 grassland sites spread over 750 km2. This pattern was six times stronger in older compared with newer rodent exclosures, indicating enclosed populations were still increasing. Floral herbivory, which reduces or prevents reproduction in this biennial plant, decreased by 99% in rodent exclosures compared with control plots. Additionally, seedling establishment was nearly eight times higher in seed‐addition subplots within versus outside of rodent exclosures.

Synthesis. Our findings illustrate how biotic resistance from granivory and florivory of native generalist rodents can provide an important ecosystem service by strongly limiting the local abundance of a widely distributed exotic weed.
Which traits determine shifts in the abundance of tree species in a fire‐prone savanna?
Authors: Higgins Steven I. , Bond William J. , Combrink Henri , Craine Joseph M. , February Edmund C. , Govender Navashni , Lannas Kathryn , Moncreiff Glenn , Trollope Winston S. W.
Published: May 2013

Fire is a process that shapes the structure and composition of vegetation in many regions. Species in these regions have presumably evolved life‐history strategies that allow success in fire‐prone environments.

In this study, we examine the extent to which the ecological success of savanna trees is determined by traits that enhance the capacity to tolerate fire and/or traits indicative of an ecophysiological capacity for rapid growth. We define ecological success as the relative change in stem density over the course of a long‐term (circa 40 year) fire experiment conducted in the Kruger National Park, South Africa.

We first examine the extent to which differences in the capacity of trees to tolerate fire can be explained by allometries describing bark traits and tree size. We then examine whether these differences in fire tolerance traits can explain observed shifts in abundance.

We show that species differ in their topkill responses (probability of above‐ground mortality) and that these differences are explained in part by differences in bark moisture content and the allometry between height and diameter. Contrary to previous studies, we find no evidence that bark thickness is important in explaining susceptibility to topkill.

Synthesis. Fire tolerance traits did explain a significant component of the variance in observed shifts in the abundance of tree species. However, traits related to the carbon economy of photosynthesis were also important.
One‐sided competition for light promotes coexistence of forest trees that share the same adult height
Authors: Kohyama Takashi S. , Takada Takenori
Published: May 2013

Coexistence of tree species is usually explained in relation to horizontal heterogeneity of forests caused by disturbance. In contrast, it remains unknown whether one‐sided competition for light in vertically structured forests contributes to stable coexistence of tree species that share the same adult height, even without horizontal heterogeneity. And if so, it is needed to specify the conditions of stable coexistence in terms of demographic and allometric traits between species. To answer these questions, we employ a theoretical model that describes dynamics of tree populations in forests of which vertical structure is expediently divided by height classes.

We carry out analytical examination for a forest with two height classes where tree populations are adult in canopy and juvenile in understorey. Demographic processes in the canopy are regulated by foliage density in the canopy, whereas juvenile survival is suppressed by overall foliage density in both classes.

A between‐species difference in juvenile/adult ratio of foliage density is required for coexistence equilibrium of two species to exist. The difference in juvenile/adult ratio in equilibrium is determined by demographic and allometric parameters of species.

Trade‐offs between demographic parameters are necessary for a coexistence equilibrium which is either stable or unstable. A species with high fecundity and/or shade‐free juvenile survival can stably coexist with a species with high shade‐free growth rate and/or adult survival, whereas it cannot stably coexist with a species with high shade tolerance in growth rate and/or in adult survival. Difference in shade tolerance in juvenile survival does not contribute to stable coexistence. Height‐foliage allometry contributes only additionally to enhance coexistence equilibrium.

When we divide forests into three height classes, up to three species can coexist, by means of demographic trade‐offs that bring about interspecific differentiation in vertical foliage distribution. We show all possible cases of coexistence among canopy (C), subcanopy (S) and understorey (U) species in terms of maximum adult height as follows: CCC, CCS, CCU, CSS and CSU.

Synthesis. Our theoretical model shows that demographic trade‐offs among tree species with identical demographic responses to shade promotes stable coexistence through vertical foliage partitioning. This mechanism works independently of the coexistence mechanism through horizontal partitioning of patch mosaic, which is associated with interspecific difference in shade tolerance.
Methicillin‐Resistant Staphylococcal Contamination of Clothing Worn by Personnel in a Veterinary Teaching Hospital
Authors: Singh Ameet , Walker Meagan , Rousseau Joyce , Monteith Gabrielle J. , Weese Jeffrey Scott
Published: May 2013

Objective

To determine the methicillin‐resistant Staphylococcus aureus (MRSA) and methicillin‐resistant Staphylococcus pseudintermedius (MRSP) contamination rate of white coats (WC) and surgical scrubs (SS) worn by personnel at the Ontario Veterinary College Health Sciences Centre (OVCHSC) and to identify risk factors associated with clothing contamination.

Study Design

Cross‐sectional study.

Sample Population

Personnel including clinical faculty, house officers, technicians, and veterinary students working at the OVCHSC.

Methods

Electrostatic cloths were used to sample WC and SS of hospital personnel. Samples were tested for MRSA and MRSP and isolates were typed. Participants completed a self‐administered questionnaire and data was evaluated for risk factors.

Results

Of 114 specimens, MRS were isolated from 20 (17.5%), MRSA from 4 (3.5%), and MRSP from 16 (14.0%). Technicians were 9.5× (OR = 0.95, 95% CI: 1.2–∞, P = .03) more likely than students to have clothing contaminated with MRSA. No risk factors were identified for MRSP or for overall MRS contamination.

Conclusions

Standard hospital clothing was found to have a high prevalence of MRS contamination in a veterinary teaching hospital and could be a source of hospital‐acquired infections.
Numerical Modeling of the Side Flow in Tape Casting of a Non‐Newtonian Fluid
Authors: Jabbari M. , Hattel J. H.
Published: May 2013

One of the most common ways used to produce multilayer ceramics (MLC) is tape casting. In this process, the dried tape thickness is of great interest to control the desired products and applications. One of the parameters that influences the final tape thickness is the side flow factor (α) which is mostly measured at the end of the process by a volumetric comparison of the tape which flowed outside the casting width to the tape within the casting width. This phenomenon has not been predicted theoretically yet in the literature. In this study, the flow of (La0.85Sr0.15)0.9MnO3 (LSM) slurry in the tape casting process is modeled numerically with ANSYS FLUENT in combination with an Ostwald‐de Waele power law constitutive equation. Based on rheometer experiments, the constants in the Ostwald‐de Waele power law are identified for the considered LSM material and applied in the numerical modeling. This model is then used for different values of substrate velocity, initial doctor blade height and material load in the reservoir, to investigate their effect on α. It is found that this factor mostly ranges between 0.8 and 0.9. Results of the modeling are compared with experimental findings and good agreement is found.
Low‐Temperature Transformation of Titania Thin Films from Amorphous Nanowires to Crystallized Nanoflowers for Heterogeneous Photocatalysis
Authors: Sun Jing , Wen Wei , Wu Jin‐Ming
Published: May 2013

Titania thin films with ordered nanostructures are of general interest in fields of photocatalysis, gas sensors, energy storages, energy conversions, etc. In this study, we report a low‐temperature crystallization and the simultaneously occurred morphology change of titania thin films in a dilute H2SO4 solution. Amorphous titania nanowire arrays were fabricated by a Ti–H2O2 interaction, which transformed to crystallized nanoflower arrays through a dissolution–precipitation route during the subsequent acid treatments. The nanoflowers were doped with nitrogen and also incorporated with sulfate ions. An increasing H2SO4 concentration resulted in larger nanoflowers with higher anatase content; but the crystallinity reduced. The low‐temperature‐derived nanoflower arrays possessed high density of surface hydroxyl groups and defect VO‐Ti3+ sites, which contributed to a high absorption and enhanced photodegradation efficiency of rhodamine B in water under the illumination of UV–visible light during the first several runs of photocatalytic evaluations. The beneficial surface defects diminished gradually with increasing runs; however, the average reaction rate constants of the acid treated films are still superior to that of the calcinated one, which can be attributed to several structural parameters such as the nanoflower morphology, incorporation of sulfate ions, and the coexistence of anatase and rutile.
Are Toleration and Respect Compatible?
Authors: Carter Ian
Published: May 2013

Toleration and respect are often thought of as compatible, and indeed complementary, liberal democratic ideals. However, it has sometimes been said that toleration is disrespectful, because it necessarily involves a negative evaluation of the object of toleration. This article shows how toleration and respect are compatible as long as ‘respect’ is taken to mean (what some moral philosophers have called) recognition respect, as opposed to appraisal respect. But it also argues that recognition respect itself rules out certain kinds of evaluation of persons, and with these, certain bases for toleration: if recognition respect is really distinct from appraisal respect, and if the fundamental rights assigned to people on the basis of recognition respect are to be equal rights, then recognition respect must itself involve a refusal to evaluate certain basic agential capacities of persons when deliberating about how to treat them. Even where ‘respect’ means recognition respect, then, there is some truth both in the thesis that toleration and respect are compatible, and in the thesis that they are incompatible. The different truths in these two theses help to shed light on the nature of toleration considered specifically as a liberal democratic virtue. This point can be illustrated by showing how the foregoing analysis provides a plausible solution to the so‐called ‘paradox of the tolerant racist’.
To confront or not to confront: non‐targets' evaluations of and responses to racist comments
Authors: Dickter Cheryl L. , Newton Virginia A.
Published: May 2013

The current studies explore situational and individual factors affecting non‐target perceivers' reactions and behavior following a racist comment, focusing on verbal confronting behavior. Two studies were conducted in which participants reported about recent situations in which they witnessed a racist comment that was not directed specifically at their own racial group. Results indicated that only one third of participants directly confronted the commenter. Strength of verbal confrontation was predicted by affective reactions and judgments of the offensiveness of the prejudicial comment. Analyses also revealed that strength of confrontation for females was predicted by the experience of negative emotions, but that males confronted more with stronger ratings of the offensiveness of the racist remarks. Implications for theory and policy are discussed.
Conformity and counter‐conformity to anti‐discrimination norms: the moderating effect of attitude toward foreigners and perceived in‐group threat
Authors: Falomir‐Pichastor Juan Manuel , Chatard Armand , Selimbegovic Leila , Konan Paul N'Dri , Mugny Gabriel
Published: May 2013

Two studies examined the influence of an anti‐discrimination norm on Swiss nationals' discrimination against foreigners as a function of initial attitude (pro‐foreigner vs. anti‐foreigner) and in‐group threat (i.e., whether or not foreigners are perceived as taking nationals' jobs). Results showed that anti‐foreigners decreased their level of discrimination (i.e., a conformity effect) when threat was low, but did not change (Study 1) or increased discrimination (i.e., a counter‐conformity effect) when threat was high (Study 2). No significant effects were observed for pro‐foreigners. It is argued that conformity to anti‐discrimination norms increases as the individual–norm discrepancy increases, insofar as the social context provides legitimacy to this norm (i.e., low in‐group threat conditions).
A time to make (and lose) friends: effects of soccer tournaments on German adolescents' attitudes toward foreigners
Authors: Gniewosz Burkhard , Noack Peter , Kessler Thomas , Eckstein Katharina
Published: May 2013

The present research examined the effects of one's national sports team defeats in international competitions on adolescents' out‐group attitudes and the moderation of these effects by in‐group identification. We conducted two longitudinal studies surveying German adolescents (Soccer World Championship 2006 and European Championship 2008). Both studies showed deterioration in adolescents' evaluations of people from the countries whose soccer teams defeated the German team (Italy and Spain). There was no generalization to other national groups. The deterioration in out‐group evaluations was shown to be more pronounced for adolescents reporting a high in‐group identification. The results are discussed in terms of macro‐societal effects on adolescents' attitude development and the function that intergroup bias serves for social identity.
Discontinuous gas exchange exhibition is a heritable trait in speckled cockroaches Nauphoeta cinerea
Authors: Schimpf N. G. , Matthews P. G. D. , White C. R.
Published: May 2013

The regulation of insect respiratory gas exchange has long been an area of interest. In particular, the reason why insects from at least five orders exhibit patterns of gas exchange that include regular periods of spiracular closure has been the source of much controversy. Three adaptive hypotheses propose that these discontinuous gas‐exchange cycles (DGCs) evolved to either limit water loss across respiratory surfaces, facilitate gas exchange in underground environments or to limit oxidative damage. It is possible that DGCs evolved independently multiple times and for different reasons, but for DGCs to be a plausible target for natural selection, they must be heritable and confer a fitness benefit. In a previous study of cockroaches Nauphoeta cinerea, we demonstrated that DGCs are repeatable and extend survival under food and water restriction. Here, we show for the first time that DGCs are heritable, suggesting that they are a plausible target for natural selection.
Genetic drift or natural selection? Hybridization and asymmetric mitochondrial introgression in twoCaribbean lizards (Anolis pulchellusandAnolis krugi)
Authors: Jezkova T. , Leal M. , Rodríguez‐Robles J. A.
Published: May 2013

Hybridization and gene introgression can occur frequently between closely related taxa, but appear to be rare phenomena among members of the species‐rich West Indian radiation ofAnolislizards. We investigated the pattern and possible mechanism of introgression between two sister species from Puerto Rico,Anolis pulchellusandAnolis krugi,using mitochondrial (ND2) and nuclear (DNAH3,NKTR)DNAsequences. Our findings demonstrated extensive introgression ofA. krugimtDNA(k‐mtDNA) into the genome ofA. pulchellusin western Puerto Rico, to the extent thatk‐mtDNAhas mostly or completely replaced the native mtDNAofA. pulchelluson this part of the island. We proposed two not mutually exclusive scenarios to account for the interspecific matings betweenA. pulchellusandA. krugi. We inferred that hybridization events occurred independently in several populations, and determined thatk‐mtDNAhaplotypes harboured in individuals ofA. pulchelluscan be assigned to four of the five major mtDNAclades ofA. krugi. Further, the spatial distribution ofk‐mtDNAclades in the two species is largely congruent. Based on this evidence, we concluded that natural selection was the probable driving mechanism for the extensivek‐mtDNAintrogression intoA. pulchellus. Our two nuclear data sets yielded different results.DNAH3 showed reciprocal monophyly ofA. pulchellusandA. krugi, indicating no effect of hybridization on this marker. In contrast, the two species shared nineNKTRalleles, probably due to incomplete lineage sorting. Our study system will provide an excellent opportunity to experimentally assess the behavioural and ecological mechanisms that can lead to hybridization in closely related taxa.
The role of local ecology during hybridization at the initial stages of ecological speciation in a marine snail
Authors: Galindo J. , Martínez‐Fernández M. , Rodríguez‐Ramilo S. T. , Rolán‐Alvarez E.
Published: May 2013

Hybrid zones of ecologically divergent populations are ideal systems to study the interaction between natural selection and gene flow during the initial stages of speciation. Here, we perform an amplified fragment length polymorphism (AFLP) genome scan in parallel hybrid zones between divergent ecotypes of the marine snailLittorina saxatilis, which is considered a model case for the study of ecological speciation. Ridged‐Banded (RB) and Smooth‐Unbanded (SU) ecotypes are adapted to different shore levels and microhabitats, although they present a sympatric distribution at the mid‐shore where they meet and mate (partially assortatively). We used shell morphology, outlier and nonoutlierAFLPloci fromRB,SUand hybrid specimens captured in sympatry to determine the level of phenotypic and genetic introgression. We found different levels of introgression at parallel hybrid zones and nonoutlier loci showed more gene flow with greater phenotypic introgression. These results were independent from the phylogeography of the studied populations, but not from the local ecological conditions. Genetic variation at outlier loci was highly correlated with phenotypic variation. In addition, we used the relationship between genetic and phenotypic variation to estimate the heritability of morphological traits and to identify potential Quantitative Trait Loci to be confirmed in future crosses. These results suggest that ecology (exogenous selection) plays an important role in this hybrid zone. Thus, ecologically based divergent natural selection is responsible, simultaneously, for both ecotype divergence and hybridization. On the other hand, genetic introgression occurs only at neutral loci (nonoutliers). In the future, genome‐wide studies and controlled crosses would give more valuable information about this process of speciation in the face of gene flow.