2,238 research outputs found

    Contracted Representation of Yang's Space-Time Algebra and Buniy-Hsu-Zee's Discrete Space-Time

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    Motivated by the recent proposition by Buniy, Hsu and Zee with respect to discrete space-time and finite spatial degrees of freedom of our physical world with a short- and a long-distance scales, lPl_P and L,L, we reconsider the Lorentz-covariant Yang's quantized space-time algebra (YSTA), which is intrinsically equipped with such two kinds of scale parameters, λ\lambda and RR. In accordance with their proposition, we find the so-called contracted representation of YSTA with finite spatial degrees of freedom associated with the ratio R/λR/\lambda, which gives a possibility of the divergence-free noncommutative field theory on YSTA. The canonical commutation relations familiar in the ordinary quantum mechanics appear as the cooperative Inonu-Wigner's contraction limit of YSTA, λ0\lambda \to 0 and $R \to \infty.

    Religious vs. Secular Communities: Sources of Social Support for Emerging Adult Black Gay and Bisexual Men

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    This research investigates factors that contribute to emerging adult black gay and bisexual men’s sources of social support. Participants were 20 Black, gay/bisexual men between 18-25 years old (Mage = 22.8, SD = 1.7). Researchers conducted semi-structured interviews and utilized grounded theory to determine intersectionality between participants’ religious upbringing as well as their racial, spiritual, sexual, and HIV identities. Participants who self-identified as bisexual continued to seek social support within churches despite having endured repeated exposure to negative religious rhetoric pertaining to same-sex behavior in religious settings. Participants who self-identified as queer did not seek social support within churches. While a majority of participants who self-identified as gay did not seek social support from churches, gay participants who did seek social support from churches were also HIV positive. A majority of participants indicated having to seek social support from communities that did not encompass all of their identities (racial, sexual, religious/spiritual, HIV) and expressed feelings of not belonging or being fully accepted by those communities as a result. Data from this research indicates a need for further research examining Black men’s sexual and religious identity self-labeling tendencies as well as HIV status as predictors of likelihood to seek social support in religious communities, specifically, black churches. A greater understanding of the factors that contribute to emerging adult, Black, gay/bisexual men’s selection of communities for social support may benefit community organizers in the development of groups that could act as sources of resiliency, especially for individuals who are living with HIV

    Textile additive manufacturing: An overview

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    Additive manufacturing (3D-printing) is a rapidly emerging technology grouped under the heading of Industry 4.0 and revolutionises the way products are created. One emerging area is textiles (apparel) where additive manufacturing allows the rapid fabrication of products that are not easily produced using traditional manufacturing approaches. In this review, we provide an overview of recent developments in textile additive manufacturing highlighting this exciting and rapidly growing research area and offer insights into the future perspectives of this promising and innovative technology

    Dynamical mass generation in quantum field theory : some methods with application to the Gross-Neveu model and Yang-Mills theory

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    We introduce some techniques to investigate dynamical mass generation. The Gross-Neveu model (GN) is used as a toy model, because the GN mass gap is exactly known, making it possible to check reliability of the various methods. Very accurate results are obtained. Also application to SU(N) Yang-Mills (YM) is discussed.Comment: 8 LaTeX2e pages, uses Kluwer class file crckbked.cls. Kluwer package included. To appear in: Proceedings of the NATO Advanced Research Workshop on "Confinement, Topology, and other Non-Perturbative Aspects of QCD", Stara Lesna, Slovakia, 21-27 jan 200

    External vs. Innate: Sources of Resiliency Among Emerging Adults, Black Gay and Bisexual Men

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    The purpose of this research was to examine the main sources and origins of resiliency that are present among Black gay and bisexual men. Resiliency refers to one’s response to adversity and ability to positively adapt to difficult situations. Twenty participants ranging in age between 18-25 years old (M = 22.8 years, SD = 1.7 years) participated in a semi-structured interview. Participants indicated varying sources of resiliency, which they utilize to encounter hardships. Innate sources (i.e., I was born this way) and external sources (i.e., music, my grandmother’s spirit) were conveyed by participants as mechanisms to overcome adversity. The current findings seek to increase social understanding of the means through which these emerging adults overcome adversity, in effort to decrease social marginalization, stigmatization, and discrimination

    T-Branes and Monodromy

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    We introduce T-branes, or "triangular branes," which are novel non-abelian bound states of branes characterized by the condition that on some loci, their matrix of normal deformations, or Higgs field, is upper triangular. These configurations refine the notion of monodromic branes which have recently played a key role in F-theory phenomenology. We show how localized matter living on complex codimension one subspaces emerge, and explain how to compute their Yukawa couplings, which are localized in complex codimension two. Not only do T-branes clarify what is meant by brane monodromy, they also open up a vast array of new possibilities both for phenomenological constructions and for purely theoretical applications. We show that for a general T-brane, the eigenvalues of the Higgs field can fail to capture the spectrum of localized modes. In particular, this provides a method for evading some constraints on F-theory GUTs which have assumed that the spectral equation for the Higgs field completely determines a local model.Comment: 110 pages, 5 figure

    Counting Exceptional Instantons

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    We show how to obtain the instanton partition function of N=2 SYM with exceptional gauge group EFG using blow-up recursion relations derived by Nakajima and Yoshioka. We compute the two instanton contribution and match it with the recent proposal for the superconformal index of rank 2 SCFTs with E6, E7 global symmetry.Comment: 16 pages, references adde

    Use of Screen-printed Electrodes Modified by Prussian Blue and Analogues in Sensing of Cysteine

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    © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The utilisation of screen-printing technology allows for a mass scalable approach for the production of electrochemical screen-printed electrodes (SPEs) and the presence of a redox mediator can add new possibilities to the electrochemical properties of the SPEs. Among the materials used as redox mediators, cyanidoferrates polymers can be used for electro-oxidation of cysteine. In this work, two monomers, namely, [Fe(CN) 6 ] 4− and [Fe(CN) 5 NH 3 ] 3− were used to produce Prussian blue (PB) and Prussian blue-Ammine (PB-Ammine), respectively. In addition, two modification methods were compared, firstly via a drop-casting and secondly by the incorporation of these materials into a printable ink. The SPE modified by PB-Ammine (drop-casting) exhibits the highest electroactive area, however the highest heterogeneous rate constant was found with the SPE modified by PB-Ammine that was incorporated into the ink. The highest value of the constant of electro-oxidation of cysteine and lowest limit of detection was also observed in the SPE modified by PB incorporated into the ink. These studies suggest that the electrocatalytic properties of SPE modified by PB and PB-Ammine are dependent upon the availability of Fe 3+ catalytic sites and the increased kinetics of the chemical reaction between the catalytic sites and the analyte

    Ni−Fe (Oxy)hydroxide Modified Graphene Additive Manufactured (3D-Printed) Electrochemical Platforms as an Efficient Electrocatalyst for the Oxygen Evolution Reaction

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    © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim We demonstrate that polylactic acid (PLA)/graphene additive manufactured (3D-printed) electrodes (Gr/AMEs) electrodeposited with Ni−Fe (oxy)hydroxide can efficiently catalyse the oxygen evolution reaction (OER). X-ray photoelectron spectroscopy (XPS) depth profiling combined with Atomic Force Microscopy (AFM) and Tip Enhanced Raman Spectroscopy (TERS) deduced the composition and depth of the Ni−Fe (oxy)hydroxide layer. The composition of the resulting electrocatalytic surfaces are tailored through altering the concentrations of nickel and iron within the electrodeposited solutions, which give rise to optimised AMEs OER performance (within 0.1 M KOH). The optimal OER performance was observed from a Ni−Fe (oxy)hydroxide with a 10 % content of Fe, which displayed an OER onset potential and overpotential of+1.47 V (vs. RHE) and 519 mV, respectively. These values arecomparable to that of polycrystalline Iridium (+ 1.43 V (vs. RHE) and ca. 413 mV), as well as being significantly less electropositive than a bare/unmodified AME. This work is essential for those designing, fabricating and modulating additive manufactured electrodes
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