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Introduction: The functions of terrestrial ecosystems are mainly maintained by bacteria, as a key component of microorganisms, which actively participate in the nutrient cycling of ecosystems. Currently, there are few studies have been carried out on the bacteria contributing to the soil multi-nutrient cycling in responding to climate warming, which hampers our obtainment of a comprehensive understanding of the ecological function of ecosystems as a whole. Methods: In this study, the main bacteria taxa contributing to the soil multi-nutrient cycling under the long-term warming in an alpine meadow was determined based onphysichemical properties measurement and high-throughput sequencing, and the potential reasons that warming altered the main bacteria contributing to the soil multi-nutrient cycling were further analyzed. Results: The results confirmed that the bacterial β-diversity was crucial to the soil multi-nutrient cycling. Furthermore, Gemmatimonadetes, Actinobacteria, and Proteobacteria were the main contributors to the soil multi-nutrient cycling, and played pivotal roles as keystone nodes and biomarkers throughout the entire soil profile. This suggested that warming altered and shifted the main bacteria contributing to the soil multi-nutrient cycling toward keystone taxa. Discussion: Meanwhile, their relative abundance was higher, which could make them have the advantage of seizing resources in the face of environmental pressures. In summary, the results demonstrated the crucial role of keystone bacteria in the multi-nutrient cycling under the climate warming in the alpine meadow. This has important implications for understanding and exploring the multi-nutrient cycling of alpine ecosystems under the global climate warming. [ABSTRACT FROM AUTHOR]

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Networks of trophic interactions provide a lot of information on the functioning of marine ecosystems. Beyond feeding habits, three additional traits (mobility, size, and habitat) of various organisms can complement this trophic view. The combination of traits and food web positions are studied here on a large food web database. The aim is a better description and understanding of ecological roles of organisms and the identification of the most important keystone species. This may contribute to develop better ecological indicators (e.g., keystoneness) and help in the interpretation of food web models. We use food web data from the Ecopath with Ecosim (EwE) database for 92 aquatic ecosystems. We quantify the network position of organisms by 18 topological indices (measuring centrality, hierarchy, and redundancy) and consider their three, categorical traits (e.g., for mobility: sessile, drifter, limited mobility, and mobile). Relationships are revealed by multivariate analysis. We found that topological indices belong to six different categories and some of them nicely separate various trait categories. For example, benthic organisms are richly connected and mobile organisms occupy higher food web positions.

The net ecosystem exchange (NEE) and methane (CH4) flux were measured by chamber measurements for five distinct ecotypes (areas with unique eco-hydrological characteristics) at Abbeyleix Bog in the Irish midlands over a 2-year period. The ecotypes ranged from those with high-quality peat-forming vegetation to communities indicative of degraded, drained conditions. Three of these ecotypes were located in an area where peat was extracted by hand and then abandoned and left to revegetate naturally at least 50 years prior to the start of the study. Two of the ecotypes were located on an adjacent raised bog, which although never mined for peat, was impacted by shallow drainage and then restored (by drain blocking) 6 years prior to the start of the study. Other major aspects of the carbon (C) balance, including dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and open-water CO2 evasion, were quantified for a catchment area at the study site over the same 2-year period. The ecotype average annual ecotype C balance ranged from a net C sink of -58±60 g C m -2 yr -1 , comparable to studies of intact peatlands, to a substantial C source of +205±80 g C m -2 yr -1 , with NEE being the most variable component of the C balance among the five ecotypes. Ecotype annual CH4 flux ranged from 2.7±1.4 g C- CH4 m -2 yr -1 to 14.2±4.8 g C- CH4 m -2 yr -1. Average annual aquatic C losses were 14.4 g C m -2 yr -1 with DOC, DIC, and CO2 evasion of 10.4 g C m -2 yr -1 , 1.3 g C m -2 yr -1 , and 2.7 g C m -2 yr -1 , respectively. A statistically significant negative correlation was found between the mean annual water table (MAWT) and the plot-scale NEE but not the global warming potential (GWP). However, a significant negative correlation was observed between the plot-scale percentage of Sphagnum moss cover and the GWP, highlighting the importance of regenerating this keystone genus as a climate change mitigation strategy in peatland restoration. The data from this study were then compared to the rapidly growing number of peatland C balance studies across boreal and temperate regions. The trend in NEE and CH4 flux with respect to MAWT was compared for the five ecotypes in this study and literature data from degraded/restored/recovering peatlands, intact peatlands, and bare peat sites. [ABSTRACT FROM AUTHOR]

This paper introduces a new time-frequency transform, referred to as the keystone-based cosine transform (KCT), to process real-valued multi-component linear frequency-modulated signals. Theoretical derivation shows that the KCT is a bilinear-based transform, but has a property of asymptotic linearity with negligible cross-terms. It also has high signal energy concentration. Experimental simulations show that compared with fractional cosine transform, the KCT can provide better performance on the distribution concentration and noisy signal detection. [ABSTRACT FROM AUTHOR]

The sexpartite vault was the great protagonist of the beginnings of Gothic architecture in Europe and outstanding vaulting was built using this system in Europe's important cathedrals and monasteries, such as Notre Dame de Paris or Canterbury. By making a comparative study of the principal examples we have been able to bring to light the knowledge of geometry and construction present in Early Gothic architecture and show how it evolved to the remarkable level of stereotomic development achieved in the High Gothic. The carving of the keystone was one of the most complicated challenges of the vault as it received the different tilted ribs at varying angles on plan and in elevation, which entailed considerable knowledge of geometry. The evolution of Gothic stereotomy is reflected in this element and we found three different solutions that show development using diverse techniques to facilitate geometric design and the carving process. [ABSTRACT FROM AUTHOR]

The aim of this article is to contribute to a better understanding of the dynamic of business ecosystems (BE) and, more particularly, to identify mechanisms that contribute to their decline. We conduct an historical study of the pinball ecosystem, which experienced steady growth over 60 years and then nearly disappeared. First, it is shown that the pinball case is particularly suitable for the analysis of BE. The major BE characteristics can be identified: a value proposition created by an alignment of partners, the central role played by the platform, the presence of three types of members, and interactions among actors that are based on coopetition. Then, the analysis reveals two factors that explain the decline: keystones' inability to change their business models and their substantial dependence on dominators. The historical perspective also allows us to distinguish certain specific periods in BE decline. [ABSTRACT FROM AUTHOR]

A project to save and restore town markers created in the 1920s by the Pennsylvania Department of Highways is presented. [ABSTRACT FROM AUTHOR]

Mashups enable end-users to "mix and match" data and services available on the web to create applications. Their creation is supported by a complex ecosystem of i) data providers who offer open APIs to users, ii) users who combine APIs into mashups, and iii) platforms, such as the ProgrammableWeb or Mashape, that facilitate the construction and publication of mashups. In this article, we argue that the evolution of the mashup ecosystem can be explained in terms of ecosystem niches anchored around hub or keystone APIs. The members of a niche are focused on an area of specialization (e.g., mapping applications) and contribute their knowledge to the value proposition of the ecosystem as a whole. To demonstrate the formation of niches in the mashup ecosystem, we model groups of related mashups as species, and we reconstruct the evolution of mashup species through phylogenetic analysis.

The research reported in this article attempts to discover who holds the power in open source software foundations through the analysis of governance documents. Artificial neural network analysis is used to analyse the content of the bylaws of six open source foundations (Apache, Eclipse, GNOME, Plone, Python, and SPI) for the purpose of identifying power structures. Results of the research suggest that: i) the actions of an open source software foundation are centered around one of three groups: Members, Chairman/President/Executive Director, and Board of Directors; ii) in only one of the six foundations is the Board of Directors responsible for both the community and the product; and iii) artificial neural network analysis of the content of bylaws provides unbiased insights of the power structure of open source software foundations. These results may prove useful to those who contribute to open source foundations and use their products and services.

SCADA control systems are the keystone for reliable performance optimization of wind farms. Processing into knowledge the amount of information they spread is a challenging task, involving engineering, physics, statistics and computer science skills. This work deals with SCADA data analysis methods for assessing the importance of how wind turbines align in patterns to the wind direction. In particular it deals with the most common collective phenomenon causing clusters of turbines behaving as a whole, rather than as a collection of individuality: wake effects. The approach is based on the discretization of nacelle position measurements and subsequent post-processing through simple statistical methods. A cluster, severely affected by wakes, from an onshore wind farm, is selected as test case. The dominant alignment patterns of the cluster are identified and analyzed by the point of view of power output and efficiency. It is shown that non-trivial alignments with respect to the wind direction arise and important performance deviations occur among the most frequent configurations. [ABSTRACT FROM AUTHOR]

This paper proposes a new motion parameter estimation algorithm, namely subband dual-frequency conjugate-Lv?s transform, for fast moving targets. This algorithm first constructs two subband signals with different central frequencies. Then, the two signals are shifted by different values and a new signal is constructed by multiplying one with the complex conjugate of the other. Finally, Keystone transform and LVT are performed to obtain the estimates. This method does not need any prior-knowledge of targets and can resolve the Doppler ambiguity problem when Keystone transform does not work, especially when the ambiguity number splits into two numbers. Both simulated and real data demonstrate the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

The Energy Emission Design Index (EEDI) is an index indicating the CO emission per transportation effort, for example the emitted tons CO per ton mile, to be calculated for each new design. The required index for new designs will be gradually lowered in the coming years resulting in either improved energy efficiencies or speed reductions. RoRo carriers are key stones in shore based logistical systems and as a result diverse in design speeds and main dimension ratio's. This diversity could be threatened by the relative simplicity of the EEDI regulations. This article aims to estimate the influence of the EEDI approach on 30 existing RoRo cargo carriers. The attained EEDI's per design are determined. Also the costs per transport effort are calculated based on the private costs and based on the social costs, both at the economically optimum speeds based on a uniformly applied sailing profile. The social costs are based on all emissions because the number of Environmental Special Area's is limited and the impact of speed reductions will not be limited to climate change. The expected speed reductions for these designs based on the EEDI, but also the required speed reductions when taking into account the total social costs are used to estimate the effectivity from the EEDI regulations. Amongst others it was concluded that the existing diversity in service speeds and main dimension ratio's will be jeopardized by the EEDI regulations. [ABSTRACT FROM AUTHOR]

In 2006, NASA's Stardust spacecraft delivered to Earth dust particles collected from the coma of comet 81P/Wild 2, with the goal of furthering the understanding of solar system formation. Stardust cometary samples were collected in a low-density, nanoporous silica aerogel making their study technically challenging. This article demonstrates the identification, exposure, and elemental composition analysis of particles analogous to those collected by NASA's Stardust mission using in-situ SEM techniques. Backscattered electron imaging is shown by experimental observation and Monte Carlo simulation to be suitable for locating particles of a range of sizes relevant to Stardust (down to submicron diameters) embedded within silica aerogel. Selective removal of the silica aerogel encapsulating an embedded particle is performed by cryogenic NF3-mediated electron beam-induced etching. The porous, low-density nature of the aerogel results in an enhanced etch rate compared with solid material, making it an effective, nonmechanical method for the exposure of particles. After exposure, elemental composition of the particle was analyzed by energy-dispersive X-ray spectroscopy using a high spectral resolution microcalorimeter. Signals from fluorine contamination are shown to correspond to nonremoved silica aerogel and only in residual concentrations. [ABSTRACT FROM AUTHOR]

The bacterial and archaeal community composition and the possible carbon assimilation processes and energy sources of microbial communities in oligotrophic, deep, crystalline bedrock fractures is yet to be resolved. In this study, intrinsic microbial communities from six fracture zones from 180-2300 m depths in Outokumpu bedrock were characterized using high-throughput amplicon sequencing and metagenomic prediction. Comamonadaceae-, Anaerobrancaceae- and Pseudomonadaceae-related OTUs form the core community in deep crystalline bedrock fractures in Outokumpu. Archaeal communities were mainly composed of Methanobacteraceae-affiliating OTUs. The predicted bacterial metagenomes showed that pathways involved in fatty acid and amino sugar metabolism were common. In addition, relative abundance of genes coding the enzymes of autotrophic carbon fixation pathways in predicted metagenomes was low. This indicates that heterotrophic carbon assimilation is more important for microbial communities of the fracture zones. Network analysis based on co-occurrence of OTUs revealed the keystone genera of the microbial communities belonging to Burkholderiales and Clostridiales. Bacterial communities in fractures resemble those found from oligotrophic, hydrogen-enriched environments. Serpentinization reactions of ophiolitic rocks in Outokumpu assemblage may provide a source of energy and organic carbon compounds for the microbial communities in the fractures. Sulfate reducers and methanogens form a minority of the total microbial communities, but OTUs forming these minor groups are similar to those found from other deep Precambrian terrestrial bedrock environments. [ABSTRACT FROM AUTHOR]

Main objective of this paper is to compare the field data measured on a few step-pool reaches of the Aneva River in the Northern Apennines with a reference database including a large number of fields and laboratory data derived from the wide literature on step-pool streams in order to contribute to describe their geomorphology and to understand their generating processes. A field experiment with painted particles is carried out on the Aneva River to investigate the entrainment threshold conditions for particle as large as those making up the steps, and, consequently, for the formation of new or removal of old steps. Theories about the factors controlling the development of these coarse-grained bedforms are tested against the data sets available and the antidune hypothesis is investigated and discusses as well. The reference database and the Aneva data confirm the keystone hypothesis as the most likely to account for the development of step-pool sequence. [ABSTRACT FROM AUTHOR]

Background: The drastic decline in the abundance of Caribbean acroporid corals (Acropora cervicornis, A. palmata) has prompted the listing of this genus as threatened as well as the development of a regional propagation and restoration program. Using in situ underwater nurseries, we documented the influence of coral genotype and symbiont identity, colony size, and propagation method on the growth and branching patterns of staghorn corals in Florida and the Dominican Republic. Methodology/Principal Findings: Individual tracking of> 1700 nursery-grown staghorn fragments and colonies from 37 distinct genotypes (identified using microsatellites) in Florida and the Dominican Republic revealed a significant positive relationship between size and growth, but a decreasing rate of productivity with increasing size. Pruning vigor (enhanced growth after fragmentation) was documented even in colonies that lost 95% of their coral tissue/skeleton, indicating that high productivity can be maintained within nurseries by sequentially fragmenting corals. A significant effect of coral genotype was documented for corals grown in a common-garden setting, with fast-growing genotypes growing up to an order of magnitude faster than slow-growing genotypes. Algal-symbiont identity established using qPCR techniques showed that clade A (likely Symbiodinium A3) was the dominant symbiont type for all coral genotypes, except for one coral genotype in the DR and two in Florida that were dominated by clade C, with A- and C-dominated genotypes having similar growth rates. Conclusion/Significance: The threatened Caribbean staghorn coral is capable of extremely fast growth, with annual productivity rates exceeding 5 cm of new coral produced for every cm of existing coral. This species benefits from high fragment survivorship coupled by the pruning vigor experienced by the parent colonies after fragmentation. These life-history characteristics make A. cervicornis a successful candidate nursery species and provide optimism for the potential role that active propagation can play in the recovery of this keystone species. [ABSTRACT FROM AUTHOR]

This article showcases the unique position accorded to the terras tree (Eusideroxylon zwageri Teijsm. & Binn. Lauraceae) in the Berawan culture. We collaborated with the Berawan people of the Loagan Bunut region of Sarawak, to uncover the most important tree in their culture. In a group interview, the participants ranked the terras as the most important tree. The Identified Cultural Influence of Cultural Keystone Species (ICI) and the Use Value Index (UV) was found to be extraordinarily high at 35 and 6.05 respectively. The multidimensional use value of the tree, stemming from its hardy timber, could be the reason behind its cultural importance. We conclude that the terras tree should be protected even outside the national parks for its ecological and cultural value. [ABSTRACT FROM AUTHOR]

We reply to the comments of De Natale and Pino (2013) on the paper ‘Are the source models of the M 7.1 1908 Messina Straits earthquake reliable? Insights from a novel inversion and sensitivity analysis of levelling data’ by Aloisi et al. (2012, Geophys. J. Int., 192, 1025–1041). We entirely reject their speculative comments and confirm our viewpoint about the impossibility of discriminating between the two oppositely dipping fault models on the basis of the levelling data alone; we state again that their role as a keystone for modellers is untenable. The comments of De Natale and Pino (2013) are welcomed insofar they give us the possibility to improve our previous analysis, and to criticize the mainstream hypothesis favouring to a low-angle East dipping fault in the Sicilian side of the Messina Straits as responsible of the 1908 destructive earthquake. [ABSTRACT FROM PUBLISHER]

In present paper we would like to share some experiences of building new education in Sports Technology at Mid Sweden University and the results of 10 years of successfully running it in Östersund. The Sports Technology education at Mid Sweden University started at Campus Östersund in 2003 as a part of the curriculum of the Engineering Department. This specialization was initially at the three-year Bachelor level, and later it was extended to an additional two-year Master level. Aiming at the quality of Sports Technology education, three keystones are underlying its process, representing the solid knowledge base, capacity to be flexible in problem solving and the use an innovative approaches. The Department unites researches with a background in both natural sciences and engineering disciplines, having a wide experience of working with and within the industry, equally active in research and teaching. The unique constellation of the profiles forming the Department include not only the SportsTech® group, being “the backbone”, but also the Ecology and Eco-technology, and Quality Technology groups bringing the excellence and extra competence needed to assure the quality of the Sports Technology education. We were the first higher education institution in Sweden to give this kind of education program and now some other Swedish Universities have followed us. Our success can be measured by a number of graduates taking good jobs in the industry. We also enjoy a steady flow of new students coming from all parts of Sweden, and Sports Technology education stays among the most desirable ones in the country. [ABSTRACT FROM AUTHOR]

Network security processors are critical components of high-performance systems built for cybersecurity. Development of a network security processor requires multi-domain experience in semiconductors and complex software security applications, and multiple iterations of both software and hardware implementations. Limited by the business models in use today, such an arduous task can be undertaken only by large incumbent companies and government organizations. Neither the "fabless semiconductor" models nor the silicon intellectual-property licensing ("IP-licensing") models allow small technology companies to successfully compete. This article describes an alternative approach that produces an ongoing stream of novel network security processors for niche markets through continuous innovation by both large and small companies. This approach, referred to here as the "business ecosystem model for network security processors", includes a flexible and reconfigurable technology platform, a "keystone" business model for the company that maintains the platform architecture, and an extended ecosystem of companies that both contribute and share in the value created by innovation. New opportunities for business model innovation by participating companies are made possible by the ecosystem model. This ecosystem model builds on: i) the lessons learned from the experience of the first author as a senior integrated circuit architect for providers of public-key cryptography solutions and as the owner of a semiconductor startup, and ii) the latest scholarly research on technology entrepreneurship, business models, platforms, and business ecosystems. This article will be of interest to all technology entrepreneurs, but it will be of particular interest to owners of small companies that provide security solutions and to specialized security professionals seeking to launch their own companies. [ABSTRACT FROM AUTHOR]

Mashups enable end-users to "mix and match" data and services available on the web to create applications. Their creation is supported by a complex ecosystem of i) data providers who offer open APIs to users, ii) users who combine APIs into mashups, and iii) platforms, such as the ProgrammableWeb or Mashape, that facilitate the construction and publication of mashups. In this article, we argue that the evolution of the mashup ecosystem can be explained in terms of ecosystem niches anchored around hub or keystone APIs. The members of a niche are focused on an area of specialization (e.g., mapping applications) and contribute their knowledge to the value proposition of the ecosystem as a whole. To demonstrate the formation of niches in the mashup ecosystem, we model groups of related mashups as species, and we reconstruct the evolution of mashup species through phylogenetic analysis. [ABSTRACT FROM AUTHOR]

Various entities have been designated keystone resources, but few tests have been attempted and we are unaware of any experimental manipulations of purported keystone resources. Mistletoes (Loranthaceae) provide structural and nutritional resources within canopies, and their pervasive influence on diversity led to their designation as keystone resources. We quantified the effect of mistletoe on diversity with a woodland-scale experiment, comparing bird diversities before and after all mistletoe plants were removed from 17 treatment sites, with those of 11 control sites and 12 sites in which mistletoe was naturally absent. Three years after mistletoe removal, treatment woodlands lost, on average, 20.9 per cent of their total species richness, 26.5 per cent of woodland-dependent bird species and 34.8 per cent of their woodland-dependent residents, compared with moderate increases in control sites and no significant changes in mistletoe-free sites. Treatment sites lost greater proportions of birds recorded nesting in mistletoe, but changes in species recorded feeding on mistletoe did not differ from control sites. Having confirmed the status of mistletoe as a keystone resource, we suggest that nutrient enrichment via litter-fall is the main mechanism promoting species richness, driving small-scale heterogeneity in productivity and food availability for woodland animals. This explanation applies to other parasitic plants with high turnover of enriched leaves, and the community-scale influence of these plants is most apparent in low productivity systems. [ABSTRACT FROM AUTHOR]

- Keystones removed from the Stardust cometary collector show varying degrees of visible fluorescence when exposed to UV light, with the brightest fluorescence associated with the space-exposed surface. We investigated the spatial characteristics of this phenomenon further by using fluorescence microscopy, confocal Raman microscopy, and synchrotron Fourier transform infrared (FTIR) spectromicroscopy. Twenty-four keystones, extracted from the Stardust cometary collector, were analyzed. Fluorescence measurements show two distributions with different excitation characteristics, indicating the presence of at least two distinct fluorophores. The first distribution is confined to within about 10 μm of the space-exposed surface, whereas the second distribution is much broader with a maximum that is typically about 30-50 μm below the surface. Confocal Raman measurements did not reveal any changes associated with the surface; however, only features associated with aliphatic hydrocarbons were strong enough to be observed. FTIR measurements, on the other hand, show two distinct distributions at the space-exposed surface: (1) a narrow, surface-confined distribution originating from −O3SiH groups and (2) a broader, sub-surface distribution originating from −O2SiH2 groups. These functional groups were not observed in keystones extracted from the cometary flight spare or from the Stardust interstellar collector, indicating that they may result at least partially from cometary exposure. The presence of O3SiH and O2SiH2 groups at the comet-exposed surface suggests that the enhanced surface fluorescence is caused by defects in the O-Si-O network and not by organic contamination. [ABSTRACT FROM AUTHOR]

Abstract: A detailed microwear study was performed on several assemblages from Northeast Africa to provide an anthropological scenario of late middle and upper Pleistocene populations in the Nile Valley and adjacent zones. Results are presented from the wear analysis of five sites, and an interpretation is provided of the keystones of MSA behaviour and its evolution throughout about 150,000 years. Locally available raw materials were predominantly used. Different tool uses were identified based on wear evidence, and it was demonstrated that stone tools were hafted from at least the early MSA onwards. In particular stone tools for which hafting was a necessity for their use, such as percussion implements and projectiles, were hafted. Both tool functions remain important throughout the Middle Stone Age. For tools with other uses, such as knives, hafting was demonstrated in certain cases. Hafting proved to be integrated into the stone tool production process, indicating a certain degree of anticipation and planning. Ochre was present at most of the sites in different forms, and mainly seems to have served a utilitarian function, and a possible symbolic use. The included sites could be interpreted as specialised sites, and in all but one case were situated in a production context. The evidence indicates the existence of a regional settlement system with different logistic nodes. [Copyright &y& Elsevier]

We studied a cohort-based, long-lived species to determine whether favorable periods that promote regeneration are driven by local, regional, or global-scale factors. Limited demographic data exist for the keystone species Carnegiea gigantea over its range. We obtained a data set collected for 12,232 plants over an area of more than 11 km2 at a restricted military zone, located far from any other studied population. We developed the establishment pattern for the species over the last 200 yr and compared population growth trends with those for other sites and with global-scale volcanism, which has been previously linked to the regeneration of the species. This population was significantly related to the two closer sites, suggesting a regional influence in regeneration and cohort establishment. Other eastern sites like ours also exhibited a regeneration peak in the 1920s. This population was not significantly related to volcanic eruptions, as has been documented elsewhere, though this may be due to subsequent mortality at the site, which would have effectively erased the record of establishment in past periods. Unlike past work, our study goes beyond a single population. We synthesized data from other known populations in order to produce, for the first time, a coherent picture of the patterns of regeneration over much of the species' range. Large-scale climatic (e.g., unusually rainy periods) and geologic (global-scale volcanism) events promote the establishment of cohorts during the same time periods historically, though to differing extents in different populations: hot, western populations have particularly large cohorts in response to volcanism, while more eastern sites may have observable cohorts during known wetter periods. Thus, these different large-scale phenomena appear to be of varying significance in a population on the basis of the population's location and associated environment. This provides insight into global climate change impacts on the species, whose keystone status will ultimately affect the success of and changes in the entire biome. [ABSTRACT FROM AUTHOR]

The influence of keystone consumers on community structure is frequently context-dependent; the same species plays a central organising role in some situations, but not others. On Christmas Island, in the Indian Ocean, a single species of omnivorous land crab, Gecarcoidea natalis, dominates the forest floor across intact rainforest. We hypothesised that this consumer plays a key role in regulating seedling recruitment and in controlling litter dynamics on the island, independent of the type of vegetation in which it occurred. To test this hypothesis, we conducted crab exclusion experiments in two forest types on the island and followed the dynamics of seedling recruitment and litter processing for six years. To determine if these effects were likely to be general across the island, we compared land crab densities and seedling abundance and diversity at ten sites across island rainforest. Surveys across island rainforest showed that seedlings of species susceptible to predation by land crabs are consistently rare. Abundance and diversity of these species were negatively correlated to red crab abundance. Although red land crabs may be important determinants of seedling recruitment to the overstorey, differences in overstorey and seedling composition at the sites suggests that recruitment of vulnerable trees still occurs at a temporal scale exceeding that of this study. These “windows” of recruitment may be related to infrequent events that reduce the effects of land crabs. Our results suggest that unlike the context dependence of most keystone consumers in continental systems, a single consumer, the red land crab, consistently controls the dynamics of seedling recruitment across this island rainforest. [ABSTRACT FROM AUTHOR]

1. Ecosystems have higher-order emerging properties that can affect the conservation of species. We identify some of these properties in order to facilitate a better understanding of them. 2. Nonlinear, indirect effects of food web interactions among species can produce counterintuitive changes in populations. 3. Species differ in their roles and linkages with other species in the system. These roles are a property of the system. Such differences in roles influence how we conserve individual species. 4. Ecosystems operate at a multitude of interacting spatial and temporal scales, which together structure the system and affect the dynamics of individual populations. 5. Disturbance also structures an ecosystem, producing both long-term slow changes and sudden shifts in ecosystem dynamics. 6. Ecosystems therefore can have multiple states, determined both by disturbance regimes and biotic interactions. Conservation should recognize a possible multiplicity of natural states while avoiding aberrant (human-induced) states. 7. Ecosystem processes are influenced by the composition of the biota they contain. Disturbances to the biota can distort processes and functions, which in turn can endanger individual species. 8. The goal of ecosystem conservation is the long-term persistence of the biota in the system. There are two paradigms: community-based conservation (CBC) and protected area conservation. Both have their advantages but neither is sufficient to protect the biota on its own. 9. CBC is required to conserve the majority of the world's biota not included in protected areas. However, current CBC methods favour a few idiosyncratic species, distort the species complex, and ignore the majority. More comprehensive methods are required for this approach to meet the goal of ecosystem conservation. 10. Protected areas are essential to conserve species unable to coexist with humans. They also function as ecological baselines to monitor the effects of humans on their own ecosystems. 11. However, protected areas suffer from loss of habitat through attrition of critical areas. Thus, renewal (addition) of habitat is required in order to achieve the long-term persistence of biota in functioning ecosystems. Identification of minimum habitat areas and restoration of ecosystems become two major priorities for future research. [ABSTRACT FROM AUTHOR]

Presents information on a study to examine the consequences of extreme spatial and temporal variation in the recruitment of a prey species supporting keystone and diffuse predation. Information on the keystone predator's hypothesis; Methodology used to conduct the study; Results of the study; Discussion based on the results of the study.

Florence Cathedral continues to yield surprises, and it is not always necessary to dig for them. A detail as small and seemingly insignificant as a keystone is here revealed as evidence of a trecento project for a set of minor lanterns. Ironically, but for good reasons, this scheme was abandoned by the very architects who in all likelihood actually crafted the keystone, Filippo Brunelleschi and Lorenzo Ghiberti. The detail is full of implications about Early Renaissance architectural practice, and it would be the first documented, completed architectural "work" involving Brunelleschi. [ABSTRACT FROM AUTHOR]

The article discusses the importance of creativity and bricolage in ancient Renaissance architecture. According to the author, architectural collections are composed of sculpture, low reliefs and columns which displayed the appropriation of antiquity. It is expressed that the reassemblages of these structures made direct reference to their origins. The arrangement of pediments, historical friezes, keystones, pilasters, frames and balustrades functioned as quotations of ancient temples, thermae, villas and palaces.

Conflict between humans and large predators is a longstanding challenge that can present negative consequences for humans and wildlife. Sharks have a global distribution and are considered to pose a potential threat to humans; concurrently many shark species are themselves threatened. Developing strategies for coexistence between humans and this keystone group is imperative. We assess blimp surveillance as a technique to simply and effectively reduce shark encounters at ocean beaches and determine the social acceptance of this technique as compared to an established mitigation strategy—shark meshing. We demonstrate the suitability of blimps for risk mitigation, with detection probabilities of shark analogues by professional lifeguards of 0.93 in ideal swimming conditions. Social surveys indicate strong social acceptance of blimps and preference for non-lethal shark mitigation. We show that continuous aerial surveillance can provide a measurable reduction in risk from sharks, improving beach safety and facilitating coexistence between people and wildlife. [ABSTRACT FROM AUTHOR]

The article discusses the planned transformation of Penn Museum keystone galleries into showcases of collections that tell stories of mankind's past as of spring 2016. Topics covered include the current "The Golden Age of King Midas," and the renovation and innovation for the Ancient Middle East, Asian, and Egyptian gallery spaces. Also noted is the galleries' expected engagement of visitors of all ages.