1,142 research outputs found

    Mapping spaces in Quasi-categories

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    We apply the Dwyer-Kan theory of homotopy function complexes in model categories to the study of mapping spaces in quasi-categories. Using this, together with our work on rigidification from [DS1], we give a streamlined proof of the Quillen equivalence between quasi-categories and simplicial categories. Some useful material about relative mapping spaces in quasi-categories is developed along the way

    Sporotrichosis: The Significance of Variations in Morphology of Spores in the Tissues

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    The histopathological diagnosis of sporotrichosis is briefly reviewed. The primary lesion consists basically of pseudo-epitheliomatous hyperplasia of the epidermis, intra-epidermal micro-abscesses, a non-specific dermal infiltrate and granulomata composed of central micro-abscess surrounded by a zone of histiocytes and multinucleated giant cells. The significance of the asteroid body is discussed. Evidence is presented to support the view that the development of asteroid bodies and the amount of eosinophilic material in these bodies is related to host resistance and that cigar bodies are found in those cases with little or no resistance and in whom the disease disseminates rapidly and wildly. Avenues of research are suggested

    Rigidification of quasi-categories

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    We give a new construction for rigidifying a quasi-category into a simplicial category, and prove that it is weakly equivalent to the rigidification given by Lurie. Our construction comes from the use of necklaces, which are simplicial sets obtained by stringing simplices together. As an application of these methods, we use our model to reprove some basic facts from Lurie's "Higher Topos Theory" regarding the rigidification process.Comment: 26 page

    Factors associated with postharvest ripening heterogeneity of "Hass" avocados (Persea americana Mill)

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    Indexación: Web of ScienceIntroduction. 'Hass' is the main avocado cultivar commercialized worldwide. The extended flowering period, very low percentage of fruit set and inability to ripen on the tree renders the fruit heterogeneous and unpredictable during postharvest management. The "triggered" and "ready-to-eat" growing markets for 'Hass' avocados are affected by the variable postharvest ripening or ripening heterogeneity which creates severe logistical problems for marketers and inconsistent quality delivery to consumers. Synthesis. The dry matter content, the current avocado harvest index that correlates very well with oil content, has been extensively used to harvest 'Hass' avocados to comply with the minimum standards to guarantee consumer satisfaction. However, previous work and empirical experience demonstrate that dry matter does not correlate on a fruit-to-fruit basis with time to reach edible ripeness. Thus, avocados of very different ages are harvested from individual trees, resulting in heterogeneous postharvest ripening of fruit within a specific batch. Several preharvest factors related to environmental and growing conditions and crop management as well as postharvest technology strategies influence the observed variability of postharvest ripening. Conclusion. Modern approaches based on studying the composition of individual fruits displaying contrasting postharvest ripening behavior, combined with non-destructive phenotyping techniques, seem to offer practical solutions for the fresh supply chain of avocados to sort fruit based on their ripening capacity.http://www.pubhort.org/fruits/2016/5/fruits160045.ht

    4q32-q35 and 6q16-q22 are valuable candidate regions for split hand/foot malformation

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    On the basis of the Human Cytogenetic Database, a computerized catalog of the clinical phenotypes associated with cytogenetically detectable human chromosome aberrations, we collected from the literature 102 cases with chromosomal aberrations and split hand/foot malformation or absent fingers/toes. Statistical analysis revealed a highly significant association (P<0.001) between the malformation and the chromosomal bands 4q32-q35, 5q15, 6q16-q22 and 7q11.2-q22 (SHFM1). Considering these findings, we suggest additional SHFM loci on chromosome 4q, 6q and probably 5q. The regions 4q and 6q have already been discussed in the literature as additional SHFM loci. We now show further evidence. In the proposed regions, there are interesting candidate genes such as, on 4q: HAND2, FGF2, LEF1 and BMPR1B; on 5q: MSX2, FLT4, PTX1 and PDLIM7; and on 6q: SNX3, GJA1, HEY2 and Tbx18.European Journal of Human Genetics advance online publication, 18 February 2009; doi:10.1038/ejhg.2009.11

    Deuteron-equivalent and phase-equivalent interactions within light nuclei

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    Background: Phase-equivalent transformations (PETs) are well-known in quantum scattering and inverse scattering theory. PETs do not affect scattering phase shifts and bound state energies of two-body system but are conventionally supposed to modify two-body bound state observables such as the rms radius and electromagnetic moments. Purpose: In order to preserve all bound state observables, we propose a new particular case of PETs, a deuteron-equivalent transformation (DET-PET), which leaves unchanged not only scattering phase shifts and bound state (deuteron) binding energy but also the bound state wave function. Methods: The construction of DET-PET is discussed; equations defining the simplest DET-PETs are derived. We apply these simplest DET-PETs to the JISP16 NNNN interaction and use the transformed NNNN interactions in calculations of 3^3H and 4^4He binding energies in the No-core Full Configuration (NCFC) approach based on extrapolations of the No-core Shell Model (NCSM) basis space results to the infinite basis space. Results: We demonstrate the DET-PET modification of the npnp scattering wave functions and study the DET-PET manifestation in the binding energies of 3^3H and 4^4He nuclei and their correlation (Tjon line). Conclusions: It is shown that some DET-PETs generate modifications of the central component while the others modify the tensor component of the NNNN interaction. DET-PETs are able to modify significantly the npnp scattering wave functions and hence the off-shell properties of the NNNN interaction. DET-PETs give rise to significant changes in the binding energies of 3^3H (in the range of approximately 1.5 MeV) and 4^4He (in the range of more than 9 MeV) and are able to modify the correlation patterns of binding energies of these nuclei

    A Design of a Material Assembly in Space-Time Generating and Storing Energy

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    The paper introduces a theoretical background of the mechanism of electromagnetic energy and power accumulation and its focusing in narrow pulses travelling along a transmission line with material parameters variable in 1D-space and time. This mechanism may be implemented due to a special material geometry- a distribution of two different dielectrics in a spatio-temporal checkerboard. We concentrate on the practically reasonable means to bring this mechanism into action in a device that may work both as energy generator and energy storage. The basic ideas discussed below appear to be fairly general; we have chosen their electromagnetic implementation as an excellent framework for the entire concept

    Database queries and constraints via lifting problems

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    Previous work has demonstrated that categories are useful and expressive models for databases. In the present paper we build on that model, showing that certain queries and constraints correspond to lifting problems, as found in modern approaches to algebraic topology. In our formulation, each so-called SPARQL graph pattern query corresponds to a category-theoretic lifting problem, whereby the set of solutions to the query is precisely the set of lifts. We interpret constraints within the same formalism and then investigate some basic properties of queries and constraints. In particular, to any database π\pi we can associate a certain derived database \Qry(\pi) of queries on π\pi. As an application, we explain how giving users access to certain parts of \Qry(\pi), rather than direct access to π\pi, improves ones ability to manage the impact of schema evolution

    Electromagnetic multipole moments of elementary spin-1/2, 1, and 3/2 particles

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    We study multipole decompositions of the electromagnetic currents of spin-1/2, 1, and 3/2 particles described in terms of Lagrangians designed to reproduce representation specific wave equations which are second order in the momenta and which emerge within the recently elaborated Poincar\'e covariant projector method. We calculate the electric multipoles of the above spins for the spinor, the four-vector, and the four-vector--spinor representations, attend to the most general non-Lagrangian spin-3/2 currents which are allowed by Lorentz invariance to be of third order in the momenta and construct the linear current equivalent of identical multipole moments of one of them. We conclude that such non-Lagrangian currents are not necessarily more general than the two-term currents emerging within the covariant projector method. We compare our results with those of the conventional Proca-, and Rarita-Schwinger frameworks. Finally, we test the representation dependence of the multipoles by placing spin-1 and spin-3/2 in the respective (1,0)\oplus(0,1), and (3/2,0)\oplus(0,3/2) single-spin representations. We observe representation independence of the charge monopoles and the magnetic dipoles, in contrast to the higher multipoles, which turn out to be representation dependent. In particular, we find the bi-vector (1,0)(0,1)(1,0)\oplus (0,1) to be characterized by an electric quadrupole moment of opposite sign to the one found in (1/2,1/2)(1/2,1/2), and consequently, to the WW boson. Our finding points toward the possibility that the ρ\rho meson could transform as part of an antisymmetric tensor with an a1a_{1} meson-like state as its representation companion.Comment: 27 pages, 2 figure
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