17,236 research outputs found

    Does Pyrrhonism Have Practical or Epistemic Value?

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    My purpose in this paper is to examine whether Pyrrhonian skepticism, as this stance is described in Sextus Empiricus’s extant works, has practical or epistemic value. More precisely, I would like to consider whether the Pyrrhonist’s suspension of judgment (ἐποχή) and undisturbedness (ἀταραξία) can be deemed to be of practical or epistemic value. By ‘practical’ value I mean both moral value and prudential value. Moral value refers to moral rightness and wrongness; prudential value to the value of well-being, personal or social. Hence, when I ask whether the Pyrrhonist’s suspension and undisturbedness have practical value, I mean whether they make us behave in a manner that is morally right or wrong, and whether they allow us to attain those goals that would make it possible to live well. As for ‘epistemic’ value, it refers basically to the values of attaining truth and avoiding error. Hence, when I ask whether the Pyrrhonist’s suspension has epistemic value, I mean whether it allows us to attain truth and avoid error. My main focus will be the practical value of both suspension and undisturbedness because this is the value on which ancient philosophy scholars critical of Pyrrhonism have laid emphasis. The reason for examining the epistemic value of suspension is that doing so will enable a fuller assessment of the significance of Pyrrhonism as a kind of philosophy, which is my primary concern

    Generalized Heine Identity for Complex Fourier Series of Binomials

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    In this paper we generalize an identity first given by Heinrich Eduard Heine in his treatise, {\it Handbuch der Kugelfunctionen, Theorie und Anwendungen (1881), which gives a Fourier series for 1/[zcosψ]1/21/[z-\cos\psi]^{1/2}, for z,ψRz,\psi\in\R, and z>1z>1, in terms of associated Legendre functions of the second kind with odd-half-integer degree and vanishing order. In this paper we give a generalization of this identity as a Fourier series of 1/[zcosψ]μ1/[z-\cos\psi]^\mu, where z,\mu\in\C, z>1|z|>1, and the coefficients of the expansion are given in terms of the same functions with order given by 12μ\frac12-\mu. We are also able to compute certain closed-form expressions for associated Legendre functions of the second kind.Comment: 12 page

    On the time variability of gamma-ray sources: A numerical analysis of variability indices

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    We present a Monte Carlo analysis of the recently introduced variability indices τ\tau (Tompkins 1999) and II (Zhang et al. 2000 & Torres et al. 2001) for γ\gamma-ray sources. We explore different variability criteria and prove that these two indices, despite the very different approaches used to compute them, are statistically correlated (5 to 7σ\sigma). This conclusion is maintained also for the subset of AGNs and high latitude (b>10|b|>10 deg) sources, whereas the correlation is lowered for the low latitude ones, where the influence of the diffuse galactic emission background is strong.Comment: Small changes to match published version in Astronomische Nachrichten (2001). Paper accepted in July 200

    Light emitting devices based on nanostructured semiconductors

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    Light emitting devices based on high-efficiency photoluminescence (PL) fluorescent nanocrystals have been investigated in terms of the generation of light from the structure using a variety of deposition methods. An automated modified layer-by-layer (LbL) self-assembly technique has been employed to produce multilayers of thiol-capped red fluorescing CdTe nanocrystals. Indium- tin-oxide (ITO) and aluminium electrodes were used as the electrodes. Morphological characterization was carried out through Schottky field effect (SFEG) SEM and atomic force microscopy (AFM). The structures built presented clear red electroluminescence (EL) to the naked eye. Turn on voltages were found to be in the range of 3-6 volts while the onset current was in the order of tens of microamperes. The role of structure homogeneity, the presence of pinholes and lifetime extension were features addressed during this investigation. Samples with a lifetime of continuous operation in air longer than 60 minutes and highly stable EL spectra were achieved; EL was visible to the unaided eye, although the brightness was still below the commercial standards and has not yet been qualified

    European Wireless 2019; 25th European Wireless Conference. Aarhus, Denmark

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    This paper describes a new design of Reed-Solomon (RS) codes when using composite extension fields. Our ultimate goal is to provide codes that remain Maximum Distance Separable (MDS), but that can be processed at higher speeds in the encoder and decoder. This is possible by using coefficients in the generator matrix that belong to smaller (and faster) finite fields of the composite extension and limiting the use of the larger (and slower) finite fields to a minimum. We provide formulae and an algorithm to generate such constructions starting from a Vandermonde RS generator matrix and show that even the simplest constructions, e.g., using only processing in two finite fields, can speed up processing by as much as two-fold compared to a Vandermonde RS and Cauchy RS while using the same decoding algorithm, and more than two-fold compared to other RS Cauchy and FFT-based RS

    Oral Clefts with Associated Anomalies: Findings in the Hungarian Congenital Abnormality Registry

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    BACKGROUND: Over the years, great efforts have been made to record the frequency of orofacial clefts in different populations. However, very few studies were able to account for the etiological and phenotypic heterogeneity of these conditions. Thus, data of cases with syndromic orofacial clefts from large population-based studies are infrequent. METHODS: Clinically recognized and notified syndromes and associations including cleft lip with or without cleft palate and other congenital anomalies were selected from the Hungarian Congenital Abnormality Registry (HCAR) between 1973 and 1982 and prevalence rates were calculated. RESULTS: Of 3,110 cases reported as having orofacial clefts, 653 had multiple congenital abnormalities. Of these, 60 (9.2%) had a known etiology (monogenic: 25 or 3.8%, chromosomal: 31 or 4.7%, teratogenic: 4 or 0.6%). Seventy-three subjects (11.2%) had schisis in addition to the oral cleft. Skeletal anomalies were the most common malformations among cases with cleft lip with/without cleft palate (CL/P) and cleft palate (CP). Disorders of the central nervous system and cardiovascular malformations were also frequently associated. CONCLUSION: Surveillance systems, such as the HCAR, provide useful information about prevalence rates of congenital anomalies in a population. However, in a field where new syndromes are being discovered and classifications regularly updated, these rates should only be accepted as provisional.Massachusetts Center for Birth Defects Research and Prevention of the Massachusetts Department of Public Health; Peer Foundation/Cleft Palate Foundation Etiology Gran

    Accelerating scientific codes by performance and accuracy modeling

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    Scientific software is often driven by multiple parameters that affect both accuracy and performance. Since finding the optimal configuration of these parameters is a highly complex task, it extremely common that the software is used suboptimally. In a typical scenario, accuracy requirements are imposed, and attained through suboptimal performance. In this paper, we present a methodology for the automatic selection of parameters for simulation codes, and a corresponding prototype tool. To be amenable to our methodology, the target code must expose the parameters affecting accuracy and performance, and there must be formulas available for error bounds and computational complexity of the underlying methods. As a case study, we consider the particle-particle particle-mesh method (PPPM) from the LAMMPS suite for molecular dynamics, and use our tool to identify configurations of the input parameters that achieve a given accuracy in the shortest execution time. When compared with the configurations suggested by expert users, the parameters selected by our tool yield reductions in the time-to-solution ranging between 10% and 60%. In other words, for the typical scenario where a fixed number of core-hours are granted and simulations of a fixed number of timesteps are to be run, usage of our tool may allow up to twice as many simulations. While we develop our ideas using LAMMPS as computational framework and use the PPPM method for dispersion as case study, the methodology is general and valid for a range of software tools and methods
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