211 research outputs found

    Nanoscale LiZnN - luminescent half-Heusler quantum dots

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    Colloidal semiconductor quantum dots are a well-established technology, with numerous materials available either commercially or through the vast body of literature. The prevalent materials are cadmium-based and are unlikely to find general acceptance in most applications. While the III-V family of materials is a likely substitute, issues remain about its long-term suitability, and other earth-abundant materials are being explored. In this report, we highlight a nanoscale half-Heusler semiconductor, LiZnN, composed of readily available elements as a potential alternative system to luminescent II-VI and III-V nanoparticle quantum dots

    Stochastic population growth in spatially heterogeneous environments

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    Classical ecological theory predicts that environmental stochasticity increases extinction risk by reducing the average per-capita growth rate of populations. To understand the interactive effects of environmental stochasticity, spatial heterogeneity, and dispersal on population growth, we study the following model for population abundances in nn patches: the conditional law of Xt+dtX_{t+dt} given Xt=xX_t=x is such that when dtdt is small the conditional mean of Xt+dtiXtiX_{t+dt}^i-X_t^i is approximately [xiμi+j(xjDjixiDij)]dt[x^i\mu_i+\sum_j(x^j D_{ji}-x^i D_{ij})]dt, where XtiX_t^i and μi\mu_i are the abundance and per capita growth rate in the ii-th patch respectivly, and DijD_{ij} is the dispersal rate from the ii-th to the jj-th patch, and the conditional covariance of Xt+dtiXtiX_{t+dt}^i-X_t^i and Xt+dtjXtjX_{t+dt}^j-X_t^j is approximately xixjσijdtx^i x^j \sigma_{ij}dt. We show for such a spatially extended population that if St=(Xt1+...+Xtn)S_t=(X_t^1+...+X_t^n) is the total population abundance, then Yt=Xt/StY_t=X_t/S_t, the vector of patch proportions, converges in law to a random vector YY_\infty as tt\to\infty, and the stochastic growth rate limtt1logSt\lim_{t\to\infty}t^{-1}\log S_t equals the space-time average per-capita growth rate \sum_i\mu_i\E[Y_\infty^i] experienced by the population minus half of the space-time average temporal variation \E[\sum_{i,j}\sigma_{ij}Y_\infty^i Y_\infty^j] experienced by the population. We derive analytic results for the law of YY_\infty, find which choice of the dispersal mechanism DD produces an optimal stochastic growth rate for a freely dispersing population, and investigate the effect on the stochastic growth rate of constraints on dispersal rates. Our results provide fundamental insights into "ideal free" movement in the face of uncertainty, the persistence of coupled sink populations, the evolution of dispersal rates, and the single large or several small (SLOSS) debate in conservation biology.Comment: 47 pages, 4 figure

    Full Genome Characterization of the Culicoides-Borne Marsupial Orbiviruses: Wallal Virus, Mudjinbarry Virus and Warrego Viruses

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    Viruses belonging to the species Wallal virus and Warrego virus of the genus Orbivirus were identified as causative agents of blindness in marsupials in Australia during 1994/5. Recent comparisons of nucleotide (nt) and amino acid (aa) sequences have provided a basis for the grouping and classification of orbivirus isolates. However, full-genome sequence data are not available for representatives of all Orbivirus species. We report full-genome sequence data for three additional orbiviruses: Wallal virus (WALV); Mudjinabarry virus (MUDV) and Warrego virus (WARV). Comparisons of conserved polymerase (Pol), sub-core-shell 'T2' and core-surface 'T13' proteins show that these viruses group with other Culicoides borne orbiviruses, clustering with Eubenangee virus (EUBV), another orbivirus infecting marsupials. WARV shares <70% aa identity in all three conserved proteins (Pol, T2 and T13) with other orbiviruses, consistent with its classification within a distinct Orbivirus species. Although WALV and MUDV share <72.86%/67.93% aa/nt identity with other orbiviruses in Pol, T2 and T13, they share >99%/90% aa/nt identities with each other (consistent with membership of the same virus species - Wallal virus). However, WALV and MUDV share <68% aa identity in their larger outer capsid protein VP2(OC1), consistent with membership of different serotypes within the species - WALV-1 and WALV-2 respectively

    A weak group inverse for rectangular matrices

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    [EN] In this paper, we extend the notion of weak group inverse to rectangular matrices (called WweightedWGinverse) by using the weighted core EP inverse recently investigated. This new generalized inverse also generalizes the well-known weighted group inverse given by Cline and Greville. In addition, we give several representations of the W-weighted WG inverse, and derive some characterizations and properties.First author was partially supported by UNRC (Grant PPI 18/C472) and CONICET (Grant PIP 112-201501-00433CO). Third author was partially supported by Ministerio de Economia, Industria y Competitividad of Spain (Grants DGI MTM2013-43678-P and Red de Excelencia MTM2017-90682-REDT).Ferreyra, DE.; Orquera, V.; Thome, N. (2019). A weak group inverse for rectangular matrices. Revista de la Real Academia de Ciencias Exactas Físicas y Naturales Serie A Matemáticas. 113(4):3727-3740. https://doi.org/10.1007/s13398-019-00674-9S372737401134Ben-Israel, A., Greville, T.N.E.: Generalized Inverses: Theory and Applications, 2nd edn. Springer, New York (2003)Baksalary, O.M., Trenkler, G.: Core inverse of matrices. Linear Multilinear Algebra 58, 681–697 (2010)Baksalary, O.M., Trenkler, G.: On a generalized core inverse. Appl. Math. Comput. 236, 450–457 (2014)Bajodah, A.H.: Servo-constraint generalized inverse dynamics for robot manipulator control design. Int. J. Robot. Autom. 25, (2010). https://doi.org/10.2316/Journal.206.2016.1.206-3291Campbell, S.L., Meyer Jr., C.D.: Generalized Inverses of Linear transformations. SIAM, Philadelphia (2009)Cline, R.E., Greville, T.N.E.: A Drazin inverse for rectangular matrices. Linear Algebra Appl. 29, 53–62 (1980)Dajić, A., Koliha, J.J.: The weighted g-Drazin inverse for operators. J. Aust. Math. Soc. 2, 163–181 (2007)Doty, K.L., Melchiorri, C., Bonivento, C.: A theory of generalized inverses applied to robotics. Int. J. Rob. Res. 12, 1–19 (1993)Drazin, M.P.: Pseudo-inverses in associate rings and semirings. Am. Math. Mon. 65, 506–514 (1958)Ferreyra, D.E., Levis, F.E., Thome, N.: Revisiting of the core EP inverse and its extension to rectangular matrices. Quaest. Math. 41, 265–281 (2018)Ferreyra, D.E., Levis, F.E., Thome, N.: Maximal classes of matrices determining generalized inverses. Appl. Math. Comput. 333, 42–52 (2018)Gigola, S., Lebtahi, L., Thome, N.: The inverse eigenvalue problem for a Hermitian reflexive matrix and the optimization problem. J. Comput. Appl. Math. 291, 449–457 (2016)Hartwig, R.E.: The weighted * ∗ -core-nilpotent decomposition. Linear Algebra Appl. 211, 101–111 (1994)Kirkland, S.J., Neumann, M.: Group inverses of M-matrices and their applications. Chapman and Hall/CRC, London (2013)Malik, S., Thome, N.: On a new generalized inverse for matrices of an arbitrary index. Appl. Math. Comput. 226, 575–580 (2014)Male sˇ{{\check{\rm s}}} s ˇ ević, B., Obradović, R., Banjac, B., Jovović, I., Makragić, M.: Application of polynomial texture mapping in process of digitalization of cultural heritage. arXiv:1312.6935 (2013). Accessed 14 June 2018Manjunatha Prasad, K., Mohana, K.S.: Core EP inverse. Linear Multilinear Algebra 62, 792–802 (2014)Mehdipour, M., Salemi, A.: On a new generalized inverse of matrices. Linear Multilinear Algebra 66, 1046–1053 (2018)Meng, L.S.: The DMP inverse for rectangular matrices. Filomat 31, 6015–6019 (2017)Mosić, D.: The CMP inverse for rectangular matrices. Aequaetiones Math. 92, 649–659 (2018)Penrose, R.: A generalized inverse for matrices. Proc. Cambrid. Philos. Soc. 51, 406–413 (1955)Soleimani, F., Stanimirović, P.S., Soleymani, F.: Some matrix iterations for computing generalized inverses and balancing chemical equations. Algorithms 8, 982–998 (2015)Xiao, G.Z., Shen, B.Z., Wu, C.K., Wong, C.S.: Some spectral techniques in coding theory. Discrete Math. 87, 181–186 (1991)Wang, H.: Core-EP decomposition and its applications. Linear Algebra Appl. 508, 289–300 (2016)Wang, H., Chen, J.: Weak group inverse. Open Math. 16, 1218–1232 (2018)Wei, Y.: A characterization for the WW W -weighted Drazin inverse and a Crammer rule for the WW W -weighted Drazin inverse solution. Appl. Math. Comput. 125, 303–310 (2002

    National-wide data on the treatment of BPH in Korea

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    The healthcare system in Korea provides coverage to all the people who are residing in Korea, so the data of the Korea healthcare system are national-wide and relatively accurate. We obtained the recent 5-year data (2004–2008) on the treatment of BPH from the national health insurance system. We tried to determine the trends or changes of BPH treatments in Korea. Over 3.8 million men visited clinics and were prescribed one or more BPH medications, and more than 44 000 men underwent surgical treatment during 2004–2008. Compared with the year 2004, two times the patients were prescribed BPH medications in 2008. With respect to the surgical treatment, the number of cases was increased 1.6 times in 2006 compared with the previous years. The most commonly used surgical option was TURP before 2006, but laser therapy was carried out as much as TURP in 2006 and in the following years. The relative risk of laser therapy in the 50 s is 1.53 (95% CI is 1.47–1.59). In conclusion, our national-wide data for the Korean BPH patients show that these patients' medical treatment increased during the 5 years from 2004 to 2008. Laser treatment had increased and it might replace TURP in several years

    Anatomy and Taxonomic Status of the Chasmosaurine Ceratopsid Nedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U.S.A

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    Background: The validity of Nedoceratops hatcheri, a chasmosaurine ceratopsid dinosaur known from a single skull recovered in the Lance Formation of eastern Wyoming, U.S.A., has been debated for over a century. Some have argued that the taxon is an aberrant Triceratops, and most recently it was proposed that N. hatcheri represents an intermediate ontogenetic stage between ‘‘young adult’ ’ and ‘‘old adult’ ’ forms of a single taxon previously split into Triceratops and Torosaurus. Methodology/Principal Findings: The holotype skull of Nedoceratops hatcheri was reexamined in order to map reconstructed areas and compare the specimen with other ceratopsids. Although squamosal fenestrae are almost certainly not of taxonomic significance, some other features are unique to N. hatcheri. These include a nasal lacking a recognizable horn, nearly vertical postorbital horncores, and relatively small parietal fenestrae. Thus, N. hatcheri is tentatively considered valid, and closely related to Triceratops spp. The holotype of N. hatcheri probably represents an ‘‘old adult,’ ’ based upon bone surface texture and the shape of the horns and epiossifications on the frill. In this study, Torosaurus is maintained as a genus distinct from Triceratops and Nedoceratops. Synonymy of the three genera as ontogenetic stages of a single taxon would require cranial changes otherwise unknown in ceratopsids, including additions of ossifications to the frill and repeated alternation of bone surface texture between juvenile and adult morphotypes

    Secreted Phospholipase A2 Involvement in Neurodegeneration: Differential Testing of Prosurvival and Anti-Inflammatory Effects of Enzyme Inhibition

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    There is increased interest in the contribution of secreted phospholipase A2 (sPLA2) enzymes to neurodegenerative diseases. Systemic treatment with the nonapeptide CHEC-9, a broad spectrum uncompetitive inhibitor of sPLA2, has been shown previously to inhibit neuron death and aspects of the inflammatory response in several models of neurodegeneration. A persistent question in studies of sPLA2 inhibitors, as for several other anti-inflammatory and neuroprotective compounds, is whether the cell protection is direct or due to slowing of the toxic aspects of the inflammatory response. To further explore this issue, we developed assays using SY5Y (neuronal cells) and HL-60 (monocytes) cell lines and examined the effects of sPLA2 inhibition on these homogeneous cell types in vitro. We found that the peptide inhibited sPLA2 enzyme activity in both SY5Y and HL-60 cultures. This inhibition provided direct protection to SY5Y neuronal cells and their processes in response to several forms of stress including exposure to conditioned medium from HL-60 cells. In cultures of HL-60 cells, sPLA2 inhibition had no effect on survival of the cells but attenuated their differentiation into macrophages, with regard to process development, phagocytic ability, and the expression of differentiation marker CD36, as well as the secretion of proinflammatory cytokines TNF-α and IL-6. These results suggest that sPLA2 enzyme activity organizes a cascade of changes comprising both cell degeneration and inflammation, processes that could theoretically operate independently during neurodegenerative conditions. The effectiveness of sPLA2 inhibitor CHEC-9 may be due to its ability to affect both processes in isolation. Testing potential anti-inflammatory/neuroprotective compounds with these human cell lines and their conditioned media may provide a useful screening tool prior to in vivo therapeutic applications

    Species Interactions during Diversification and Community Assembly in an Island Radiation of Shrews

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    Closely related, ecologically similar species often have adjacent distributions, suggesting competitive exclusion may contribute to the structure of some natural communities. In systems such as island archipelagos, where speciation is often tightly associated with dispersal over oceanic barriers, competitive exclusion may prevent population establishment following inter-island dispersal and subsequent cladogenesis.) species in the Philippines are the result of competitive exclusion preventing secondary invasion of occupied islands. We first compare ecological niche models between two widespread, allopatric species and find statistical support for their ecological similarity, implying that competition for habitat between these species is possible. We then examine dispersion patterns among sympatric species and find some signal for overdispersion of body size, but not for phylogenetic branch length. Finally, we simulate the process of inter-island colonization under a stochastic model of dispersal lacking ecological forces. Results are dependent on the geographic scope and colonization probability employed. However, some combinations suggest that the number of inter-island dispersal events necessary to populate the archipelago may be much higher than the minimum number of colonization events necessary to explain current estimates of species richness and phylogenetic relationships. If our model is appropriate, these results imply that alternative factors, such as competitive exclusion, may have influenced the process of inter-island colonization and subsequent cladogenesis.We interpret the combined results as providing tenuous evidence that similarity in body size may prevent co-occurrence in Philippine shrews and that competitive exclusion among ecologically similar species, rather than an inability to disperse among islands, may have limited diversification in this group, and, possibly other clades endemic to island archipelagos

    New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism

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    Background:\ud During much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia. Remarkably, previous studies have postulated the occurrence of latitudinally arrayed dinosaur “provinces,” or “biomes,” on Laramidia. Yet this hypothesis has been challenged on multiple fronts and has remained poorly tested.\ud \ud Methodology/Principal Findings:\ud Here we describe two new, co-occurring ceratopsids from the Upper Cretaceous Kaiparowits Formation of Utah that provide the strongest support to date for the dinosaur provincialism hypothesis. Both pertain to the clade of ceratopsids known as Chasmosaurinae, dramatically increasing representation of this group from the southern portion of the Western Interior Basin of North America. Utahceratops gettyi gen. et sp. nov.—characterized by short, rounded, laterally projecting supraorbital horncores and an elongate frill with a deep median embayment—is recovered as the sister taxon to Pentaceratops sternbergii from the late Campanian of New Mexico. Kosmoceratops richardsoni gen. et sp. nov.—characterized by elongate, laterally projecting supraorbital horncores and a short, broad frill adorned with ten well developed hooks—has the most ornate skull of any known dinosaur and is closely allied to Chasmosaurus irvinensis from the late Campanian of Alberta.\ud \ud Conclusions/Significance:\ud Considered in unison, the phylogenetic, stratigraphic, and biogeographic evidence documents distinct, co-occurring chasmosaurine taxa north and south on the diminutive landmass of Laramidia. The famous Triceratops and all other, more nested chasmosaurines are postulated as descendants of forms previously restricted to the southern portion of Laramidia. Results further suggest the presence of latitudinally arrayed evolutionary centers of endemism within chasmosaurine ceratopsids during the late Campanian, the first documented occurrence of intracontinental endemism within dinosaurs
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