bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical evaluation of wind speed frequency distribution functions
Authors: Celik A. N. , Makkawi A. , Muneer T.
Published: March 2010

Over the past few years a number of new mathematical functions have been proposed for wind speed probability density distributions. The most commonly used function that has been cited in literature has been the two-parameter Weibull function. However, in recent years studies have shown that the two-parameter Weibull function might be inadequate in modeling the wind speed probability density distributions or independent of whether the distribution is of unimodal or bimodal nature. For the unimodal distributions, the inadequacy may be due to the intricate behavior of the distribution, which prevents it to be satisfyingly modeled by a two-parameter model. For the bimodal behavior, the two-parameter Weibull function, which produces only a unimodal distribution, is simply inadequate to model it appropriately. Therefore, in recent years, alternative functions have been suggested for both unimodal and bimodal distributions, seeking more involved functions to better model these distributions. This article involves the modeling of observed wind speed probability density distributions using the main body of models found in the literature, namely, Rayleigh, Lognormal, two-parameter Weibull, three-parameter Weibull, and bimodal Weibull probability distribution functions. One of the important steps in the evaluation of different functions is the interpretation of the statistical parameters, namely, slope, R2, mean bias error, and root mean squared error, as are presently used in this article. A novel statistical tool is developed in the present article using these four statistical parameters. The novel tool can be used to evaluate the relative performance of models when more than one model is involved or to determine the overall accuracy of a particular model for a specific site. The calculations are made based on the long term wind speed data collected at 4-s interval at the experimental site at Edinburgh Napier University.
Superintense fields from multiple ultrashort laser pulses retroreflected in circular geometry
Authors: Ooi C. H. Raymond
Published: March 2010

Laser field with superintensity beyond 1029 W/cm2 can be generated by coherent superposition of multiple 100 fs laser pulses in circular geometry setup upon retroreflection by a ring mirror. We have found the criteria for attaining such intensities using broadband ring mirror within the practical damage threshold and paraxial focusing regime. Simple expressions for the intensity enhancement factor are obtained, providing insight for achieving unlimited laser intensity. Higher intensities can be achieved by using few-cycle laser pulses.
Modeling of the rf discharge initiation in a negative ion source
Authors: Yoshinari S. , Hayami T. , Terasaki R. , Hatayama A. , Fukano A.
Published: March 2010

The maintenance free rf ion source is expected to be one of the most promising candidates for the negative ion sources of plasma heating for future fusion reactors. As an alternative to the arc-discharge sources, the rf negative ion sources have been developed for H− production. In order to make clear the condition for the discharge initiation of the rf source, we are developing a numerical model using the finite difference time domain Monte Carlo method to analyze the electron energy distribution function in rf field. The numerical result shows that the discharge is not successfully initiated due to the wall loss unless the wall potential is considered. More self-consistent model including ion dynamics to evaluate the wall potential and the electron loss at the wall will be needed in the future.
Enhanced dye-sensitized solar cell using graphene-TiO2 photoanode prepared by heterogeneous coagulation
Authors: Sun Shengrui , Gao Lian , Liu Yangqiao
Published: March 2010

In this study, dye-sensitized solar cells (DSSC) were fabricated using graphene-TiO2 composite photoanodes. The graphene-TiO2 nanocomposites were prepared using the heterogeneous coagulation between Nafion-coated graphene and commercial TiO2 (P25) nanoparticles, which ensured a tight interfacial binding between them. The DSSC incorporating 0.5 wt  % graphene in the TiO2 photoanode demonstrates a power conversion efficiency of 4.28%, which is 59% higher than that without graphene. It was found that the incorporated graphene caused both increased dye adsorption and significant longer electron lifetime. Graphene has been proven to be an attractive candidate for improving the performance of DSSC.
From a ‘Borderless World’ to a ‘World of Borders’: ‘Bringing History Back in’
Authors: O'Dowd Liam
Published: March 2010

The first part of the paper explores some of the reasons why contemporary border studies understate the full significance of state borders and their global primacy. It is argued that this failing is rooted in a much wider lack of historical reflexivity—a reluctance to acknowledge the historical positioning (the ‘where and when’) of contemporary border studies themselves. This reluctance encourages a form of pseudohistory, or ‘epochal thinking’, which disfigures perspective on the present. Among the consequences are (a) exaggerated claims of the novelty of contemporary border change, propped up by poorly substantiated benchmarks in the past; (b) an incapacity to recognise the ‘past in the present’ as in the various historical deposits of state formation processes; and (c) a failure to recognise the distinctiveness of contemporary state borders and how they differ from other borders in their complexity and globality. The second part of the paper argues for a recalibration of border studies aimed at balancing their spatial emphases with a much greater, and more critical, historical sensitivity. It insists that ‘boundedness’, and state boundedness in particular, is a variable that must be understood historically. This is illustrated by arguing that a better analysis of contemporary border change means rethinking the crude periodisation which distinguishes the age of empire from the age of nation-states and, in turn, from some putative contemporary era ‘beyond nation-states’ and their borders.
On Islands, Insularity, and Opium Poppies: Australia's Secret Pharmacy
Authors: Williams Stewart
Published: March 2010

Islands embody a contradictory geography. Although insularity has negative connotations, the related aspects of uniqueness, smallness, secrecy, security, isolation, and remoteness all have strategic roles in situating Australia's production of licit narcotics as an international success with poppy cultivation confined to the island state of Tasmania. Through the boundaries and dualisms inscribed in the discourses of islandness and drug rhetoric, the state's ultramodern manufacture of pharmaceuticals is contrasted with others elsewhere, including opium and illegal drug production. Their representations simplify the more intricate and challenging geopolitical realities that link this industry to transnational corporations, state and federal governments, their agencies, and various UN organisations. In a poststructural reading, the secrets of islands and drugs are suggested to comprise what Derrida terms aporia or impossible situations: Tasmania and its poppy industry are isolated from a global otherness yet entwine different peoples and places in connecting complex material practices both licit and illicit at multiple scales all around the world. However, these aporia also present new political and ethical openings with significance for island studies as well as for narcotics production and its regulation.
Population age structure of the spotted tree frog (Litoria spenceri): insights into population declines
Authors: Gillespie Graeme
Published: March 2010

Context. Despite increased scientific attention on amphibian conservation in recent years, knowledge of population demography of amphibians remains scarce, hampering evaluation of population declines and development of appropriate management responses.
Aims. The aims of this research were to examine variation in population demography of the spotted tree frog (Litoria spenceri), a critically endangered species in Australia, and to evaluate the role of various factors potentially responsible for population declines such as introduced trout, chytridiomycosis and habitat changes.
Methods. Skeletochronology combined with mark–recapture sampling were undertaken in two different river systems, Bogong Creek and Taponga River, to determine population age structure. Age-specific survival estimates were derived from each population and were then used to examine variance in age-specific mortality.
Key results. Relative population density per 200 m of stream was 67.7 adults and 131.3 juveniles at Bogong Creek and 10.7 adults and 33.8 juveniles at Taponga River. Ages were determined for 578 frogs across the two populations. Age-specific survival was lowest in the first year of life compared to all other age classes, and highest in sexually mature adults. Differences in age-specific survival were similar between the populations, with the exception of first-year survivorship, which averaged 1.9% at Bogong Creek and 0.4% at Taponga River. This difference was large enough to explain most of the marked difference in population density between the two streams.
Key conclusions. The difference in first-year age-specific survival is consistent with trout predation as the most parsimonious explanation for the large differences in population density between the populations, and lends further weight to the role of introduced trout in the decline of this species.
Implications. This study has contributed to informing management actions for conservation of this species, and demonstrates that population age structure data may provide valuable insights into demographic variability within and between populations and species. This may have important implications for interpretation of population declines, and conservation and management responses.
Cat-exclusion zones in rural and urban-fringe landscapes: how large would they have to be?
Authors: Metsers Elizabeth M. , Seddon Philip J. , van Heezik Yolanda M.
Published: March 2010

Context. The process of urban sprawl brings the human population and their domestic cats (Felis catus) in close contact with wildlife in areas that were previously remote, including reserves and conservation areas created to protect populations of vulnerable or threatened species. Various mitigation measures have been proposed, including devices designed to hinder cat hunting ability, desexing to reduce wandering and nuisance behaviours, containment at night or at all times and regulations governing cat ownership. Such regulations may aim to reduce cat densities by limiting the number of cats per household, or they may define zones around sensitive conservation areas where cat ownership is prohibited. Aims. The present study sought to establish the necessary size of cat-exclusion zones in rural and urban-fringe landscapes where vulnerable prey species may also reside. Methods. With GPS collars, we tracked 38 domestic cats at three sites (one rural, two urban fringe) where small reserves contained threatened lizard species. Key results. Home ranges (95% kernel density estimates) were considerably larger for cats at the rural site (0.3–69 ha) than at urban-fringe sites (0.35–19 ha at Kaitorete Spit and 0.2–9 ha at Otago Peninsula), and were larger at night than day. Resource selection ratios indicated avoidance of open areas with little cover, such as cultivated areas (farmland), tussock grassland and duneland, whereas sources of cover such as trees and buildings were preferred. Maximum distances moved and large variability between individual cats suggest buffers in rural landscapes would need to be at least 2.4 km wide, whereas those in urban-fringe habitat could be half as large. Conclusions. Despite significant home-range size differences exhibited by cats living in rural v. urban-fringe habitats, exclusion zones would need to be wide to account for considerable inter-cat variation in movement behaviour. Implications. The size of an effective cat-exclusion zone should represent the specific landscape, amount of residential development and substantial variability between individual cats.
The success of using trained dogs to locate sparse rodents in pest-free sanctuaries
Authors: Gsell Anna , Innes John , de Monchy Pim , Brunton Dianne
Published: March 2010

Context. Better techniques to detect small numbers of mammalian pests such as rodents are required both to complete large-scale eradications in restoration areas and to detect invaders before they become abundant or cause serious impacts on biodiversity. Aims. To evaluate the ability of certified rodent dogs (Canis familiaris) to locate Norway rats (Rattus norvegicus) and mice (Mus musculus) or their scent trails at very low densities in field conditions. Methods. We experimentally tested two rodent dogs by releasing small numbers of laboratory rats and mice in a 63 ha rodent-free forest sanctuary and then determining if the dogs and their handlers could find the rodents and their scent trails. We divided the enclosure into two halves, east and west of the midpoint, and alternated releases daily between the two areas to minimise residual scent between consecutive trials. Radio-tagged rats or mice were released a total of 96 times at random locations that were unknown to handlers, followed for 50–100 m, then caught and either placed in hidden cages at the end of the scent trail or removed from the forest. Handlers and their dogs had up to 6 h to search for rodents. Key Results. Despite the extremely low density of rodents in the effective research area of 32 ha, both dogs were highly successful at finding rodents, together locating 87% of rats and 80% of mice. Handlers reported few false positive detections. We found that well-trained dogs can effectively cover 30–40 ha of steep forested habitat in half a day (6 h). Conclusions. Despite the limitations of our study design, we conclude that well-trained rodent dogs may be able to locate wild rodents at low densities in forest situations. Implications. Our results support the ongoing use of certified dogs to detect rodent survivors and invaders in conservation areas in New Zealand and elsewhere. Additional research is required to trial dogs on experimentally released wild rodents and to compare the cost-effectiveness of dogs with other detection methods.
The role of innovative global institutions in linking knowledge and action
Authors: van Kerkhoff Lorrae , Szlezák Nicole A.
Published: March 2010

It is becoming increasingly recognized that our collective ability to tackle complex problems will require the development of new, adaptive, and innovative institutional arrangements that can deal with rapidly changing knowledge and have effective learning capabilities. In this paper, we applied a knowledge-systems perspective to examine how institutional innovations can affect the generation, sharing, and application of scientific and technical knowledge. We report on a case study that examined the effects that one large innovative organization, The Global Fund to Fight AIDS, Tuberculosis, and Malaria, is having on the knowledge dimensions of decision-making in global health. The case study shows that the organization created demand for new knowledge from a range of actors, but it did not incorporate strategies for meeting this demand into their own rules, incentives, or procedures. This made it difficult for some applicants to meet the organization's dual aims of scientific soundness and national ownership of projects. It also highlighted that scientific knowledge needed to be integrated with managerial and situational knowledge for success. More generally, the study illustrates that institutional change targeting implementation can also significantly affect the dynamics of knowledge creation (learning), access, distribution, and use. Recognizing how action-oriented institutions can affect these dynamics across their knowledge system can help institutional designers build more efficient and effective institutions for sustainable development.
The dimensionality of discourse
Authors: Doxas Isidoros , Dennis Simon , Oliver William L.
Published: March 2010

The paragraph spaces of five text corpora, of different genres and intended audiences, in four different languages, all show the same two-scale structure, with the dimension at short distances being lower than at long distances. In all five cases the short-distance dimension is approximately eight. Control simulations with randomly permuted word instances do not exhibit a low dimensional structure. The observed topology places important constraints on the way in which authors construct prose, which may be universal.
Axon guidance by growth-rate modulation
Authors: Mortimer Duncan , Pujic Zac , Vaughan Timothy , Thompson Andrew W. , Feldner Julia , Vetter Irina , Goodhill Geoffrey J.
Published: March 2010

Guidance of axons by molecular gradients is crucial for wiring up the developing nervous system. It often is assumed that the unique signature of such guidance is immediate and biased turning of the axon tip toward or away from the gradient. However, here we show that such turning is not required for guidance. Rather, by a combination of experimental and computational analyses, we demonstrate that growth-rate modulation is an alternative mechanism for guidance. Furthermore we show that, although both mechanisms may operate simultaneously, biased turning dominates in steep gradients, whereas growth-rate modulation may dominate in shallow gradients. These results suggest that biased axon turning is not the only method by which guidance can occur.
Polar localization and degradation of
Arabidopsis
boron transporters through distinct trafficking pathways
Authors: Takano Junpei , Tanaka Mayuki , Toyoda Atsushi , Miwa Kyoko , Kasai Koji , Fuji Kentaro , Onouchi Hitoshi , Naito Satoshi , Fujiwara Toru
Published: March 2010

Boron (B) is essential for plant growth but is toxic when present in excess. In the roots of
Arabidopsis thaliana
under B limitation, a boric acid channel, NIP5;1, and a boric acid/borate exporter, BOR1, are required for efficient B uptake and subsequent translocation into the xylem, respectively. However, under high-B conditions, BOR1 activity is repressed through endocytic degradation, presumably to avoid B toxicity. In this study, we investigated the localization of GFP-tagged NIP5;1 and BOR1 expressed under the control of their native promoters. Under B limitation, GFP-NIP5;1 and BOR1-GFP localized preferentially in outer (distal) and inner (proximal) plasma membrane domains, respectively, of various root cells. The polar localization of the boric acid channel and boric acid/borate exporter indicates the radial transport route of B toward the stele. Furthermore, mutational analysis revealed a requirement of tyrosine residues, in a probable cytoplasmic loop region of BOR1, for polar localization in various cells of the meristem and elongation zone. The same tyrosine residues were also required for vacuolar targeting upon high B supply. The present study of BOR1 and NIP5;1 demonstrates the importance of selective endocytic trafficking in polar localization and degradation of plant nutrient transporters for radial transport and homeostasis of plant mineral nutrients.
Morphology of mixed primary and secondary organic particles and the adsorption of spectator organic gases during aerosol formation
Authors: Vaden Timothy D. , Song Chen , Zaveri Rahul A. , Imre Dan , Zelenyuk Alla
Published: March 2010

Primary organic aerosol (POA) and associated vapors can play an important role in determining the formation and properties of secondary organic aerosol (SOA). If SOA and POA are miscible, POA will significantly enhance SOA formation and some POA vapor will incorporate into SOA particles. When the two are not miscible, condensation of SOA on POA particles forms particles with complex morphology. In addition, POA vapor can adsorb to the surface of SOA particles increasing their mass and affecting their evaporation rates. To gain insight into SOA/POA interactions we present a detailed experimental investigation of the morphologies of SOA particles formed during ozonolysis of α-pinene in the presence of dioctyl phthalate (DOP) particles, serving as a simplified model of hydrophobic POA, using a single-particle mass spectrometer. Ultraviolet laser depth-profiling experiments were used to characterize two different types of mixed SOA/DOP particles: those formed by condensation of the oxidized α-pinene products on size-selected DOP particles and by condensation of DOP on size-selected α-pinene SOA particles. The results show that the hydrophilic SOA and hydrophobic DOP do not mix but instead form layered phases. In addition, an examination of homogeneously nucleated SOA particles formed in the presence of DOP vapor shows them to have an adsorbed DOP coating layer that is ∼4 nm thick and carries 12% of the particles mass. These results may have implications for SOA formation and behavior in the atmosphere, where numerous organic compounds with various volatilities and different polarities are present.
Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for atmospheric chemistry
Authors: Farmer D. K. , Matsunaga A. , Docherty K. S. , Surratt J. D. , Seinfeld J. H. , Ziemann P. J. , Jimenez J. L.
Published: March 2010

Organonitrates (ON) are important products of gas-phase oxidation of volatile organic compounds in the troposphere; some models predict, and laboratory studies show, the formation of large, multifunctional ON with vapor pressures low enough to partition to the particle phase. Organosulfates (OS) have also been recently detected in secondary organic aerosol. Despite their potential importance, ON and OS remain a nearly unexplored aspect of atmospheric chemistry because few studies have quantified particulate ON or OS in ambient air. We report the response of a high-resolution time-of-flight aerosol mass spectrometer (AMS) to aerosol ON and OS standards and mixtures. We quantify the potentially substantial underestimation of organic aerosol O/C, commonly used as a metric for aging, and N/C. Most of the ON-nitrogen appears as

ions in the AMS, which are typically dominated by inorganic nitrate. Minor organonitrogen ions are observed although their identity and intensity vary between standards. We evaluate the potential for using

fragment ratios, organonitrogen ions,

ions, the ammonium balance of the nominally inorganic ions, and comparison to ion-chromatography instruments to constrain the concentrations of ON for ambient datasets, and apply these techniques to a field study in Riverside, CA. OS manifests as separate organic and sulfate components in the AMS with minimal organosulfur fragments and little difference in fragmentation from inorganic sulfate. The low thermal stability of ON and OS likely causes similar detection difficulties for other aerosol mass spectrometers using vaporization and/or ionization techniques with similar or larger energy, which has likely led to an underappreciation of these species.
CaV1.2 β-subunit coordinates CaMKII-triggered cardiomyocyte death and afterdepolarizations
Authors: Koval Olha M. , Guan Xiaoquan , Wu Yuejin , Joiner Mei-ling , Gao Zhan , Chen Biyi , Grumbach Isabella M. , Luczak Elizabeth D. , Colbran Roger J. , Song Long-Sheng , Hund Thomas J. , Mohler Peter J. , Anderson Mark E.
Published: March 2010

Excessive activation of calmodulin kinase II (CaMKII) causes arrhythmias and heart failure, but the cellular mechanisms for CaMKII-targeted proteins causing disordered cell membrane excitability and myocardial dysfunction remain uncertain. Failing human cardiomyocytes exhibit increased CaMKII and voltage-gated Ca2+channel (CaV1.2) activity, and enhanced expression of a specific CaV1.2 β-subunit protein isoform (β2a). We recently identified CaV1.2β2aresidues critical for CaMKII phosphorylation (Thr 498) and binding (Leu 493), suggesting the hypothesis that these amino acids are crucial for cardiomyopathic consequences of CaMKII signaling. Here we show WTβ2aexpression causes cellular Ca2+overload, arrhythmia-triggering cell membrane potential oscillations called early afterdepolarizations (EADs), and premature death in paced adult rabbit ventricular myocytes. Prevention of intracellular Ca2+release by ryanodine or global cellular CaMKII inhibition reduced EADs and improved cell survival to control levels in WTβ2a-expressing ventricular myocytes. In contrast, expression ofβ2aT498A or L493A mutants mimicked the protective effects of ryanodine or global cellular CaMKII inhibition by reducing Ca2+entry through CaV1.2 and inhibiting EADs. Furthermore, CaV1.2 currents recorded from cells overexpressing CaMKII phosphorylation- or binding-incompetentβ2asubunits were incapable of entering a CaMKII-dependent high-activity gating mode (mode 2), indicating thatβ2aThr 498 and Leu 493 are required for CaV1.2 activation by CaMKII in native cells. These data show that CaMKII binding and phosphorylation sites onβ2aare concise but pivotal components of a molecular and biophysical and mechanism for EADs and impaired survival in adult cardiomyocytes.
Complete mitochondrial genome of a Pleistocene jawbone unveils the origin of polar bear
Authors: Lindqvist Charlotte , Schuster Stephan C. , Sun Yazhou , Talbot Sandra L. , Qi Ji , Ratan Aakrosh , Tomsho Lynn P. , Kasson Lindsay , Zeyl Eve , Aars Jon , Miller Webb , Ingólfsson Ólafur , Bachmann Lutz , Wiig Øystein
Published: March 2010

The polar bear has become the flagship species in the climate-change discussion. However, little is known about how past climate impacted its evolution and persistence, given an extremely poor fossil record. Although it is undisputed from analyses of mitochondrial (mt) DNA that polar bears constitute a lineage within the genetic diversity of brown bears, timing estimates of their divergence have differed considerably. Using next-generation sequencing technology, we have generated a complete, high-quality mt genome from a stratigraphically validated 130,000- to 110,000-year-old polar bear jawbone. In addition, six mt genomes were generated of extant polar bears from Alaska and brown bears from the Admiralty and Baranof islands of the Alexander Archipelago of southeastern Alaska and Kodiak Island. We show that the phylogenetic position of the ancient polar bear lies almost directly at the branching point between polar bears and brown bears, elucidating a unique morphologically and molecularly documented fossil link between living mammal species. Molecular dating and stable isotope analyses also show that by very early in their evolutionary history, polar bears were already inhabitants of the Artic sea ice and had adapted very rapidly to their current and unique ecology at the top of the Arctic marine food chain. As such, polar bears provide an excellent example of evolutionary opportunism within a widespread mammalian lineage.
The imprint of China’s first emperor on the distant realm of eastern Shandong
Authors: Feinman Gary M. , Nicholas Linda M. , Hui Fang
Published: March 2010

Imperial expansion is recurrent in human history. For early empires, such as in ancient China, this process generally is known from texts that glorify and present the perspective of victors. The legacy of the Qin king, Shihuangdi, who first unified China in 221 BC, remains vital, but we have few details about the consequences of his distant conquests or how they changed the path of local histories. We integrate documentary accounts with the findings of a systematic regional survey of archaeological sites to provide a holistic context for this imperialistic episode and the changes that followed in coastal Shandong.
SA‐I Mechanoreceptor Position in Fingertip Skin May Impact Sensitivity to Edge Stimuli
Authors: Gerling Gregory J.
Published: March 2010

Background: The skin plays a role in conditioning mechanical indentation into distributions of stress/strain that mechanoreceptors convert into neural signals. Solid mechanics methods have modelled the skin to predict the in vivo neural response from mechanoreceptors. Despite their promise, current models cannot explain the role that anatomical positioning and receptor organ morphology play in producing differences in neural response. This work hypothesises that the skin′s intermediate ridges may help explain, in part, the sensitivity of slowly adapting type I (SA‐I) mechanoreceptors to edge stimuli. Method: Two finite‐element models of the fingertip were built, validated and used to analyse the functionality of the intermediate ridges. One of the two‐dimensional, cross‐sectional models included intermediate ridges, while the other did not. The analysis sought to determine if intermediate ridges (1) increase the magnitude of strain energy density (SED) near the SA‐I location and (2) help differentiate one 2.0‐mm indenter from two 0.5‐mm wide indenters with a 1.0‐mm gap. Results: Higher concentrations of SED were found near the tips of the intermediate ridges, the anatomical location that coincides with the SA‐I receptors. This first result suggested that the location of the SA‐Is in the stiffer epidermal tissue helps magnify their response to edge stimuli. The second result was that both models were equally capable of predicting the spatial structure within the in vivo neural responses, and therefore the addition of intermediate ridges did not help in differentiating the indenters. Conclusion: The finding, a 15%–35% increase in response when the sampling point lies within the stiffer tissue at the same depth, seeks to inform the positioning of force sensors in robotic skin substrates.
Identifying an Odour Source in Fluid‐Advected Environments, Algorithms Abstracted from Moth‐Inspired Plume Tracing Strategies
Authors: Li Wei
Published: March 2010

This paper presents algorithms for identifying the odour source of a chemical plume with significant filament intermittency and meander developed in fluid‐advected environments. The algorithms are abstracted from moth‐inspired chemical plume tracing strategies in two steps. First, we introduce the concept of the last chemical detection points that leads to construction of a source identification zone and development of two variations in the source identification algorithms. Second, we use Monte Carlo methods to optimise the proposed algorithms in a simulated environment. The evaluation results demonstrate that the optimised algorithm achieves a success rate of over 90% in identifying the source location, the average identification time is 3–4 min and the average error is 1–2 m surrounding the source location.
Self-face recognition is characterized by “bilateral gain” and by faster, more accurate performance which persists when faces are inverted
Authors: Keyes Helen , Brady Nuala
Published: March 2010

We examine interhemispheric cooperation in the recognition of personally known faces whose long-term familiarity ensures frequent co-activation of face-sensitive areas in the right and left brain. Images of self, friend, and stranger faces were presented for 150 ms in upright and inverted orientations both unilaterally, in the right or left visual field, and bilaterally. Consistent with previous research, we find a bilateral advantage for familiar but not for unfamiliar faces, and we demonstrate that this gain occurs for inverted as well as upright faces. We show that friend faces are recognized more quickly than unfamiliar faces in upright but not in inverted orientations, suggesting that configural processing underlies this particular advantage. Novel to this study is the finding that people are faster and more accurate at recognizing their own face over both stranger and friend faces and that these advantages occur for both upright and inverted faces. These findings are consistent with evidence for a bilateral representation of self-faces.
Evidence that vitamin D3 promotes mast cell–dependent reduction of chronic UVB-induced skin pathology in mice
Authors: Biggs Lisa , Yu Chunping , Fedoric Boris , Lopez Angel F. , Galli Stephen J. , Grimbaldeston Michele A.
Published: March 2010

Mast cell production of interleukin-10 (IL-10) can limit the skin pathology induced by chronic low-dose ultraviolet (UV)-B irradiation. Although the mechanism that promotes mast cell IL-10 production in this setting is unknown, exposure of the skin to UVB irradiation induces increased production of the immune modifying agent 1α,25-dihydroxyvitamin D3 (1α,25[OH]2D3). We now show that 1α,25(OH)2D3 can up-regulate IL-10 mRNA expression and induce IL-10 secretion in mouse mast cells in vitro. To investigate the roles of 1α,25(OH)2D3 and mast cell vitamin D receptor (VDR) expression in chronically UVB-irradiated skin in vivo, we engrafted the skin of genetically mast cell–deficient WBB6F1-KitW/W-v mice with bone marrow–derived cultured mast cells derived from C57BL/6 wild-type or VDR−/− mice. Optimal mast cell–dependent suppression of the inflammation, local production of proinflammatory cytokines, epidermal hyperplasia, and epidermal ulceration associated with chronic UVB irradiation of the skin in KitW/W-v mice required expression of VDR by the adoptively transferred mast cells. Our findings suggest that 1α,25(OH)2D3/VDR-dependent induction of IL-10 production by cutaneous mast cells can contribute to the mast cell’s ability to suppress inflammation and skin pathology at sites of chronic UVB irradiation.
Resistance to antiangiogenic therapy is directed by vascular phenotype, vessel stabilization, and maturation in malignant melanoma
Authors: Helfrich Iris , Scheffrahn Inka , Bartling Sönke , Weis Joachim , von Felbert Verena , Middleton Mark , Kato Masahi , Ergün Süleyman , Augustin Hellmut G. , Schadendorf Dirk
Published: March 2010

Angiogenesis is not only dependent on endothelial cell invasion and proliferation, it also requires pericyte coverage of vascular sprouts for stabilization of vascular walls. Clinical efficacy of angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway is still limited to date. We hypothesized that the level of vessel maturation is critically involved in the response to antiangiogenic therapies. To test this hypothesis, we evaluated the vascular network in spontaneously developing melanomas of MT/ret transgenic mice after using PTK787/ZK222584 for anti-VEGF therapy but also analyzed human melanoma metastases taken at clinical relapse in patients undergoing adjuvant treatment using bevacizumab. Both experimental settings showed that tumor vessels, which are resistant to anti-VEGF therapy, are characterized by enhanced vessel diameter and normalization of the vascular bed by coverage of mature pericytes and immunoreactivity for desmin, NG-2, platelet-derived growth factor receptor β, and the late-stage maturity marker α smooth muscle actin. Our findings emphasize that the level of mural cell differentiation and stabilization of the vascular wall significantly contribute to the response toward antiangiogenic therapy in melanoma. This study may be useful in paving the way toward a more rational development of second generation antiangiogenic combination therapies and in providing, for the first time, a murine model to study this.
Structural basis for the methylation of G1405 in 16S rRNA by aminoglycoside resistance methyltransferase Sgm from an antibiotic producer: a diversity of active sites in m 7 G methyltransferases
Authors: Husain Nilofer , Tkaczuk Karolina L. , Shenoy Rajesh T. , Kaminska Katarzyna H. , Čubrilo Sonja , Maravić-Vlahoviček Gordana , Bujnicki Janusz M. , Sivaraman J.
Published: March 2010

Sgm (Sisomicin-gentamicin methyltransferase) from antibiotic-producing bacterium Micromonospora zionensis is an enzyme that confers resistance to aminoglycosides like gentamicin and sisomicin by specifically methylating G1405 in bacterial 16S rRNA. Sgm belongs to the aminoglycoside resistance methyltransferase (Arm) family of enzymes that have been recently found to spread by horizontal gene transfer among disease-causing bacteria. Structural characterization of Arm enzymes is the key to understand their mechanism of action and to develop inhibitors that would block their activity. Here we report the structure of Sgm in complex with cofactors S-adenosylmethionine (AdoMet) and S-adenosylhomocysteine (AdoHcy) at 2.0 and 2.1 Å resolution, respectively, and results of mutagenesis and rRNA footprinting, and protein-substrate docking. We propose the mechanism of methylation of G1405 by Sgm and compare it with other m 7 G methyltransferases, revealing a surprising diversity of active sites and binding modes for the same basic reaction of RNA modification. This analysis can serve as a stepping stone towards developing drugs that would specifically block the activity of Arm methyltransferases and thereby re-sensitize pathogenic bacteria to aminoglycoside antibiotics.
A Homeobox Gene Is Essential for Conidiogenesis of the Rice Blast Fungus Magnaporthe oryzae
Authors: Liu Wende , Xie Shiyong , Zhao Xinhua , Chen Xin , Zheng Wenhui , Lu Guodong , Xu Jin-Rong , Wang Zonghua
Published: March 2010

Magnaporthe oryzae starts its infection by the attachment of pyriform conidia on rice tissues, and severity of the disease epidemic is proportional to the quantity of conidia produced in the rice blast lesions. However, the mechanism of conidial production is not well understood. Homeodomain proteins play critical roles in regulating various growth and developmental processes in fungi and other eukaryotes. Through targeted gene replacement, we find that deletion of HTF1, one of seven homeobox genes in the fungal genome, does not affect mycelial growth but causes total defect of conidial production. Further observation revealed that the Δhtf1 mutant produces significantly more conidiophores, which curve slightly near the tip but could not develop sterigmata-like structures. Although the Δhtf1 mutant fails to form conidia, it could still develop melanized appressoria from hyphal tips and infect plants. The expression level of HTF1 is significantly reduced in the Δmgb1 G-β and ΔcpkA deletion mutant, and the ACR1 but not CON7 gene that encodes transcription factor required for normal conidiogenesis is significantly downregulated in the Δhtf1 mutant. These data suggest that the HTF1 gene is essential for conidiogenesis, and may be functionally related to the trimeric G-protein signaling and other transcriptional regulators that are known to be important for conidiation in M. oryzae.
Molecular and Evolutionary Analyses of Pseudomonas syringae pv. tomato Race 1
Authors: Kunkeaw Suparat , Tan Steven , Coaker Gitta
Published: March 2010

Pseudomonas syringae pv. tomato, the causal agent of bacterial speck of tomato, has recently become an increasing problem in California due to the evolution and prevalence of highly aggressive race 1 strains. In resistant plant genotypes, the type III effectors AvrPto and AvrPtoB are recognized by the tomato proteins Pto and Prf. We investigated the prevalence of avrPto and avrPtoB in strains collected over the last 13 years in California. All race 1 strains retained avrPtoB but did not express AvrPtoB protein at detectable levels in vitro. However, deletion of avrPtoB indicated that this effector protein is still expressed at low levels in race 1 during infection. avrPto was detected in four race 1 strains but a key amino acid polymorphism prevents this new protein from interacting with and eliciting Pto-mediated resistance. Growth curve analyses demonstrate that this new avrPto allele is still functional and can enhance P. syringae virulence on tomato. Multilocus sequence typing was used to resolve phylogenetic relationships and revealed that the majority of race 0 and 1 strains were most closely related to P. syringae T1. Collectively, these data support the hypothesis that existing P. syringae populations evolved to overcome genetic resistance by altering the expression and sequence of avrPto and avrPtoB effectors.
Peroxisome Biogenesis Factor PEX13 Is Required for Appressorium-Mediated Plant Infection by the Anthracnose Fungus Colletotrichum orbiculare
Authors: Fujihara Naoki , Sakaguchi Ayumu , Tanaka Shigeyuki , Fujii Satoshi , Tsuji Gento , Shiraishi Tomonori , O'Connell Richard , Kubo Yasuyuki
Published: March 2010

Peroxisomes are ubiquitous organelles of eukaryotic cells that fulfill a variety of biochemical functions, including β-oxidation of fatty acids. Here, we report that an ortholog of the Saccharomyces cerevisiae peroxisome biogenesis gene PEX13 is required for pathogenicity of Colletotrichum orbiculare. CoPEX13 was identified by screening random insertional mutants for deficiency in fatty acid utilization. Targeted knockout mutants of CoPEX13 were unable to utilize fatty acids as a carbon source. Expression analysis using green fluorescent protein fused to the peroxisomal targeting signals PTS1 and PTS2 revealed that the import machinery for peroxisomal matrix proteins was impaired in copex13 mutants. Appressoria formed by the copex13 mutants were defective in both melanization and penetration ability on host plants, had thin cell walls, and lacked peroxisomes. Moreover, the concentration of intracellular glycerol was lower in copex13 appressoria than those of the wild type. These findings indicate that fatty acid oxidation in peroxisomes is required not only for appressorium melanization but also for cell wall biogenesis and metabolic processes involved in turgor generation, all of which are essential for appressorium penetration ability.
Armillaria melleaInduces a Set of Defense Genes in Grapevine Roots and One of Them Codifies a Protein with Antifungal Activity
Authors: Perazzolli Michele , Bampi Federica , Faccin Silvia , Moser Mirko , De Luca Federica , Ciccotti Anna Maria , Velasco Riccardo , Gessler Cesare , Pertot Ilaria , Moser Claudio
Published: March 2010

Grapevine root rot, caused by Armillaria mellea, is a serious disease in some grape-growing regions. Young grapevines start to show symptoms of Armillaria root rot from the second year after inoculation, suggesting a certain degree of resistance in young roots. We used a suppression subtractive hybridization approach to study grapevine's reactions to the first stages of A. mellea infection. We identified 24 genes that were upregulated in the roots of the rootstock Kober 5BB 24 h after A. mellea challenge. Real-time reverse-transcriptase polymerase chain reaction analysis confirmed the induction of genes encoding protease inhibitors, thaumatins, glutathione S-transferase, and aminocyclopropane carboxylate oxidase, as well as phase-change related, tumor-related, and proline-rich proteins, and gene markers of the ethylene and jasmonate signaling pathway. Gene modulation was generally stronger in Kober 5BB than in Pinot Noir plants, and in vitro inoculation induced higher modulation than in greenhouse Armillaria spp. treatments. The full-length coding sequences of seven of these genes were obtained and expressed as recombinant proteins. The grapevine homologue of the Quercus spp. phase-change-related protein inhibited the growth of A. mellea mycelia in vitro, suggesting that this protein may play an important role in the defense response against A. mellea.
Host–pathogen coevolution, secondary sympatry and species diversification
Authors: Ricklefs Robert E.
Published: March 2010

The build-up of species locally within a region by allopatric speciation depends on geographically separated (allopatric) sister populations becoming reproductively incompatible followed by secondary sympatry. Among birds, this has happened frequently in remote archipelagos, spectacular cases including the Darwin's finches (Geospizinae) and Hawaiian honeycreepers (Drepanidinae), but similar examples are lacking in archipelagos nearer to continental landmasses. Of the required steps in the speciation cycle, achievement of secondary sympatry appears to be limiting in near archipelagos and, by extension, in continental regions. Here, I suggest that secondary sympatry might be prevented by apparent competition mediated through pathogens that are locally coevolved with one population of host and are pathogenic in sister populations. The absence of numerous pathogens in remote archipelagos might, therefore, allow sister populations to achieve secondary sympatry more readily and thereby accelerate diversification. By similar reasoning, species should accumulate relatively slowly within continental regions. In this essay, I explore the assumptions and some implications of this model for species diversification.
The influence of gene flow and drift on genetic and phenotypic divergence in two species ofZosteropsin Vanuatu
Authors: Clegg Sonya M. , Phillimore Albert B.
Published: March 2010

Colonization of an archipelago sets the stage for adaptive radiation. However, some archipelagos are home to spectacular radiations, while others have much lower levels of diversification. The amount of gene flow among allopatric populations is one factor proposed to contribute to this variation. In island colonizing birds, selection for reduced dispersal ability is predicted to produce changing patterns of regional population genetic structure as gene flow-dominated systems give way to drift-mediated divergence. If this transition is important in facilitating phenotypic divergence, levels of genetic and phenotypic divergence should be associated. We consider population genetic structure and phenotypic divergence among two co-distributed, congeneric (Genus:Zosterops) bird species inhabiting the Vanuatu archipelago. The more recent colonist,Z. lateralis, exhibits genetic patterns consistent with a strong influence of distance-mediated gene flow. However, complex patterns of asymmetrical gene flow indicate variation in dispersal ability or inclination among populations. The endemic species,Z. flavifrons, shows only a partial transition towards a drift-mediated system, despite a long evolutionary history on the archipelago. We find no strong evidence that gene flow constrains phenotypic divergence in either species, suggesting that levels of inter-island gene flow do not explain the absence of a radiation across this archipelago.
How to save the rarest Darwin's finch from extinction: the mangrove finch on Isabela Island
Authors: Fessl Birgit , Young Glyn H. , Young Richard P. , Rodríguez-Matamoros Jorge , Dvorak Michael , Tebbich Sabine , Fa John E.
Published: March 2010

Habitat destruction and predation by invasive alien species has led to the disappearance of several island populations of Darwin's finches but to date none of the 13 recognized species have gone extinct. However, driven by rapid economic growth in the Galápagos, the effects of introduced species have accelerated and severely threatened these iconic birds. The critically endangered mangrove finch (Camarhynchus heliobates) is now confined to three small mangroves on Isabela Island. During 2006–2009, we assessed its population status and monitored nesting success, both before and after rat poisoning. Population size was estimated at around only 100 birds for the two main breeding sites, with possibly 5–10 birds surviving at a third mangrove. Before rat control, 54 per cent of nests during incubation phase were predated with only 18 per cent of nests producing fledglings. Post-rat control, nest predation during the incubation phase fell to 30 per cent with 37 per cent of nests producing fledglings. During the nestling phase, infestation by larvae of the introduced parasitic fly (Philornis downsi) caused 14 per cent additional mortality. Using population viability analysis, we simulated the probability of population persistence under various scenarios of control and showed that with effective management of these invasive species, mangrove finch populations should start to recover.