1,019 research outputs found

    Linearity and Scaling of a Statistical Model for the Species Abundance Distribution

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    We derive a linear recursion relation for the species abundance distribution in a statistical model of ecology and demonstrate the existence of a scaling solution

    Equalities of ideals associated with two projections in rings with involution

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    In this article we study various right ideals associated with two projections (self-adjoint idempotents) in a ring with involution. Results of O.M. Baksalary, G. Trenkler, R. Piziak, P.L. Odell and R. Hahn about orthogonal projectors (complex matrices which are Hermitian and idempotent) are considered in the setting of rings with involution. New proofs based on algebraic arguments, rather than finite-dimensional and rank theory, are given.The authors thank the anonymous reviewer for his\her useful suggestions, which helped to improve the original version of this article. The second author is supported by Grant No. 174007 of the Ministry of Science, Technology and Development, Republic of Serbia.BenĂ­tez LĂłpez, J.; Cvetkovic-Ilic, D. (2013). Equalities of ideals associated with two projections in rings with involution. Linear and Multilinear Algebra. 61(10):1419-1435. doi:10.1080/03081087.2012.743026S141914356110Baksalary, O. M., & Trenkler, G. (2009). Column space equalities for orthogonal projectors. Applied Mathematics and Computation, 212(2), 519-529. doi:10.1016/j.amc.2009.02.042BenĂ­tez, J. (2008). Moore–Penrose inverses and commuting elements of C∗-algebras. Journal of Mathematical Analysis and Applications, 345(2), 766-770. doi:10.1016/j.jmaa.2008.04.062Green, J. A. (1951). On the Structure of Semigroups. The Annals of Mathematics, 54(1), 163. doi:10.2307/1969317Harte, R. (1992). On generalized inverses in C*-algebras. Studia Mathematica, 103(1), 71-77. doi:10.4064/sm-103-1-71-77Harte, R. (1993). Generalized inverses in C*-algebras II. Studia Mathematica, 106(2), 129-138. doi:10.4064/sm-106-2-129-138Koliha, J. J. (2000). Elements of C*-algebras commuting with their Moore-Penrose inverse. Studia Mathematica, 139(1), 81-90. doi:10.4064/sm-139-1-81-90Koliha, J. J., Cvetković-Ilić, D., & Deng, C. (2012). Generalized Drazin invertibility of combinations of idempotents. Linear Algebra and its Applications, 437(9), 2317-2324. doi:10.1016/j.laa.2012.06.005Koliha, J. J., & Rakočević, V. (2003). Invertibility of the Difference of Idempotents. Linear and Multilinear Algebra, 51(1), 97-110. doi:10.1080/030810802100023499Mary, X. (2011). On generalized inverses and Green’s relations. Linear Algebra and its Applications, 434(8), 1836-1844. doi:10.1016/j.laa.2010.11.045Von Neumann, J. (1936). On Regular Rings. Proceedings of the National Academy of Sciences, 22(12), 707-713. doi:10.1073/pnas.22.12.707Patrı́cio, P., & Puystjens, R. (2004). Drazin–Moore–Penrose invertibility in rings. Linear Algebra and its Applications, 389, 159-173. doi:10.1016/j.laa.2004.04.006Piziak, R., Odell, P. L., & Hahn, R. (1999). Constructing projections on sums and intersections. Computers & Mathematics with Applications, 37(1), 67-74. doi:10.1016/s0898-1221(98)00242-

    Wireless sensor node design for heterogeneous networks

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    Two complementary wireless sensor nodes for building two-tiered heterogeneous networks are presented. A larger node with a 25 mm by 25 mm size acts as the backbone of the network, and can handle complex data processing. A smaller, cheaper node with a 10 mm by 10 mm size can perform simpler sensor-interfacing tasks. The 25mm node is based on previous work that has been done in the Tyndall National Institute that created a modular wireless sensor node. In this work, a new 25mm module is developed operating in the 433/868 MHz frequency bands, with a range of 3.8 km. The 10mm node is highly miniaturised, while retaining a high level of modularity. It has been designed to support very energy efficient operation for applications with low duty cycles, with a sleep current of 3.3 ÎŒA. Both nodes use commercially available components and have low manufacturing costs to allow the construction of large networks. In addition, interface boards for communicating with nodes have been developed for both the 25mm and 10mm nodes. These interface boards provide a USB connection, and support recharging of a Li-ion battery from the USB power supply. This paper discusses the design goals, the design methods, and the resulting implementation

    Peptide Co-Agonists for Combined Activation of the APJ and GLP-1 Receptors with Insulinotropic and Satiety Actions Show Potential for Alleviation of Metabolic Dysfunction in Type 2 Diabetes †

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    Stable analogues of the adipokine apelin-13 have shown promising therapeutic potential via APJ receptor activation in isolated ÎČ-cells and in animal models of obesity-related diabetes. Incretin mimetics such as exenatide that bind to GLP-1 receptors are well-established Type 2 diabetes treatment options. We developed novel hybrid co-agonist peptide analogues incorporating both exendin-4(1-30) covalently linked to apelin (ELA). The dose-dependent (10−12 to 10−6 M) actions of ELA and component peptides were tested on acute (20 min) insulin secretion from cultured pancreatic BRIN-BD11 ÎČ-cells at 5.6 mmol/L glucose. In addition, separate tests were performed in the presence or absence of specific APJ and GLP-1 receptor antagonists. The co-agonist ELA peptide showed markedly greater insulinotropic actions (1.6 to 3.3-fold) than equimolar concentrations of either component peptide alone or in combination (p < 0.001). ELA and related acylated analogues (25 nmol/kg i.p. injection) were also tested on cumulative food intake in trained 21 h-fasted adult mice (n = 8), with food intake measured at 30 min intervals up to 180 min. The ELA co-agonist peptides significantly reduced food intake (3.1-fold by 180 min) in mice (p < 0.001) versus saline-treated controls. ELA peptides showed marked improvements in both insulin secretion and appetite control, raising interest in their therapeutic potential

    Land use change through the lens of macroecology : insights from Azorean arthropods and the maximum entropy theory of ecology

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    Human activity and land management practices, in particular land use change, have resulted in the global loss of biodiversity. These types of disturbance affect the shape of macroecological patterns, and therefore analyzing these patterns can provide insights into how ecosystems are affected by land use change. We here use arthropod census data from 96 sites at Terceira Island in the Azores archipelago across four different land uses of increasing management intensity: native forest, exotic forest, semi-natural pasture and intensive pasture, to examine the effects of land use type on three macroecological patterns: the species abundance distribution, the metabolic rate distribution of individuals and the species–area relationship. The maximum entropy theory of ecology (METE) has successfully predicted these patterns across habitats and taxa in undisturbed ecosystems, and thus provides a null expectation for their shapes. Across these patterns, we find that the forest habitats are the best fit by METE predictions, while the semi-natural pasture is consistently the worst fit, and the intensive pasture is intermediately well fit. We show that the direction of failure of the METE predictions at the pasture sites is likely due to the hyper-dominance of introduced spider species present there. We hypothesize that the particularly poor fit for the semi-natural pasture is due to the mix of arthropod communities out of equilibrium, leading to greater heterogeneity in composition and complex dynamics that violate METE's assumption of static state variables. The comparative better fit for the intensive pasture plausibly results from more homogeneous arthropod communities that are well adapted to intensive management, and thus whose state variables are less in flux. Analyzing deviations from theoretical predictions across land use type provides useful information about how land use and disturbance affect ecosystems, and such comparisons could be useful across other habitats and taxa.Funding for this project was provided in part by grant DEB 1751380 from the US National Science Foundation, as well as by grants to PAVB FCT-UIDP/00329/2020-2024 (Thematic Line 1 – integrated ecological assessment of environmental change on biodiversity) and MACRISK – PTDC/BIA-CBI/0625/2021, through the FCT – Fundação para a CiĂȘncia e a Tecnologia. MB acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) (PGSD2-517114-2018). Data acquisition was provided by the projects: ‘Consequences of land use change on Azorean fauna and flora – the 2010 Target' (Ref: Direcção Regional de CiĂȘncia e Tecnologia M.2.1.2/I/003/2008) and ‘Direcção Regional dos Recursos Florestais' (‘Secretaria Regional da Agricultura e Pescas') through the Project ‘Reservas Florestais dos Açores: Cartografia e Inventariação dos ArtrĂłpodes EndĂ©micos dos Açores' (PROJ. 17.01 – 080203).info:eu-repo/semantics/publishedVersio

    Modeling power in multi-functionality sensor network applications

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    Rachit Agarwal, Rafael V. Martinez-Catala, Sean Harte, Cedric Segard, Brendan O'Flynn, "Modeling Power in Multi-functionality Sensor Network Applications," sensorcomm, pp.507-512, 2008 Proceedings of the Second International Conference on Sensor Technologies and Applications, August 25-August 31 2008, Cap Esterel, FranceWith the migration of a Wireless Sensor Network (WSN) over various evolving applications, power estimation and profiling during the design cycle become critical issues and present hurdles in reducing the design time. Furthermore, with a growing size of the network, simulating the behavior of each sensor node is not feasible. It is important to devise an approach that provides a network-wide picture of power consumption and of variations in power usage under changes in the network and/or node application in the network. In this paper, we present a modular power estimation technique which simplifies the power modeling of any sensor network application. In particular, we are interested in analyzing the behavior of power consumption if one or more modules of the WSN platform in the application are changed during the design cycle or after the deployment. The proposed technique is susceptible to applications changes on the fly and is particularly beneficial in networks with large number of nodes. We perform experiments modifying parameters of a ZigBee based sensor network application such as packet size, sampling rate, functionality (encryption) and sensor types. We present the results, demonstrating an error less than 3% in all the experiments performed, and insights into the results

    InterProScan: protein domains identifier

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    InterProScan [E. M. Zdobnov and R. Apweiler (2001) Bioinformatics, 17, 847–848] is a tool that combines different protein signature recognition methods from the InterPro [N. J. Mulder, R. Apweiler, T. K. Attwood, A. Bairoch, A. Bateman, D. Binns, P. Bradley, P. Bork, P. Bucher, L. Cerutti et al. (2005) Nucleic Acids Res., 33, D201–D205] consortium member databases into one resource. At the time of writing there are 10 distinct publicly available databases in the application. Protein as well as DNA sequences can be analysed. A web-based version is accessible for academic and commercial organizations from the EBI (). In addition, a standalone Perl version and a SOAP Web Service [J. Snell, D. Tidwell and P. Kulchenko (2001) Programming Web Services with SOAP, 1st edn. O'Reilly Publishers, Sebastopol, CA, ] are also available to the users. Various output formats are supported and include text tables, XML documents, as well as various graphs to help interpret the results

    The role of orthographic neighbourhood effects in lateralized lexical decision: a replication study and meta-analysis

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    The effect of orthographic neighbourhood size (N) on lexical decision reaction time differs when words are presented in the left or right visual fields. Evidence suggests a facilitatory N effect (i.e., faster reaction times for words with larger neighbourhoods) in the left visual field. However, the N effect in the right visual field remains controversial: it may have a weaker facilitative role or it may even be inhibitory. In a pre-registered online experiment, we replicated the interaction between N and visual field and provided support for an inhibitory N effect in the right visual field. We subsequently conducted a pre-registered systematic review and meta-analysis to synthesise the available evidence and determine the direction of N effects across visual fields. Based on the evidence, it would seem the effect is inhibitory in the right visual field. Furthermore, the size of the N effect is considerably smaller in the right visual field. Both studies revealed considerable heterogeneity between participants and studies, and we consider the implications of this for future work
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