1,119 research outputs found

    Scale invariant correlations and the distribution of prime numbers

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    Negative correlations in the distribution of prime numbers are found to display a scale invariance. This occurs in conjunction with a nonstationary behavior. We compare the prime number series to a type of fractional Brownian motion which incorporates both the scale invariance and the nonstationary behavior. Interesting discrepancies remain. The scale invariance also appears to imply the Riemann hypothesis and we study the use of the former as a test of the latter.Comment: 13 pages, 8 figures, version to appear in J. Phys.

    High quality InSAR data linked to seasonal change in hydraulic head for an agricultural area in the San Luis Valley, Colorado

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    In the San Luis Valley (SLV), Colorado legislation passed in 2004 requires that hydraulic head levels in the confined aquifer system stay within the range experienced in the years 1978–2000. While some measurements of hydraulic head exist, greater spatial and temporal sampling would be very valuable in understanding the behavior of the system. Interferometric synthetic aperture radar (InSAR) data provide fine spatial resolution measurements of Earth surface deformation, which can be related to hydraulic head change in the confined aquifer system. However, change in cm-scale crop structure with time leads to signal decorrelation, resulting in low quality data. Here we apply small baseline subset (SBAS) analysis to InSAR data collected from 1992 to 2001. We are able to show high levels of correlation, denoting high quality data, in areas between the center pivot irrigation circles, where the lack of water results in little surface vegetation. At three well locations we see a seasonal variation in the InSAR data that mimics the hydraulic head data. We use measured values of the elastic skeletal storage coefficient to estimate hydraulic head from the InSAR data. In general the magnitude of estimated and measured head agree to within the calculated error. However, the errors are unacceptably large due to both errors in the InSAR data and uncertainty in the measured value of the elastic skeletal storage coefficient. We conclude that InSAR is capturing the seasonal head variation, but that further research is required to obtain accurate hydraulic head estimates from the InSAR deformation measurements

    Kinetic Isotope Effect in Chromic Acid Oxidation of Acetophenone

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    280-28

    Kinetics & Mechanism of Cr(VI) Oxidation of Isobutyraldehyde

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    705-70

    Network enabled partial reconfiguration for distributed FPGA edge acceleration

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    Partial reconfiguration supports virtualisation of applications on FPGAs, enabling compute to dynamically adapt to workloads in distributed infrastructure and datecenters. While the latter often makes use of the PCIe interface and supporting infrastructure to allocate and load compute kernels via a host CPU, FPGAs are becoming increasingly popular as standalone resources in edge-computing, requiring them to manage ac- celerators autonomously. This paper presents a platform that supports the managing of accelerator bitstreams over the network interface on a Xilinx Zynq device without intervention by the Arm processor. We compare against traditional vendor provided PR management for both library accelerators and custom acceler- ators and show that we achieve a 29% decrease in reconfiguration trigger latency using this approach

    Synthesis and liquid crystalline behaviour of substituted (E)-phenyl-4-(phenyldiazenyl) benzoate derivatives and their photo switching ability

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    Azobenzene derivatives containing phenyl/4-halogen-phenyl 4-{(E)-[4-(pent-4-en-1-yloxy)phenyl] diazenyl}benzoate group with different electronegative substituent (H, F, Cl, Br and I) at other end was synthesised. These azo-based benzoate derivatives have been characterised by FTIR, 1H-NMR, 13C-NMR, elemental analyser, POM and UV-Vis spectroscopy. Photosaturation at 358 nm obtained after 82 s of UV irradiation and the longest thermal back relaxation time of 45 h recorded by UVVis. The azo derivative could be possible photolock under UV light, as observed by the improved thermal back relaxation time. The resulting photolockable chain of azobenzene might prove valuable in the development of optical device application. These azobenzene moieties also exhibit liquid crystalline behaviour with respect to the halogen substitution as an electron withdrawing group shows that strong structure property relationship exists among them

    Build automation and runtime abstraction for partial reconfiguration on Xilinx Zynq UltraScale+

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    Partial reconfiguration (PR) is fundamental to build- ing adaptive systems on modern FPGA SoCs, where hardware can be adapted dynamically at runtime. Vendor supported reconfiguration is performance limited, drivers entail complex memory management, and software/hardware design requires detailed knowledge of the underlying hardware. This paper presents a collection of abstractions that provide high performance reconfiguration of hardware from within the Linux userspace, automating the process of building PR applications, and adding support for the Xilinx Zynq UltraScale+ architecture. We compare our abstractions against vendor tooling for PR management and open source tools supporting PR within Linux. Our tools provides automation and abstraction layers, from defining PR configurations through to compiling and packaging Linux with support for userspace PR control, targeted for non- experts

    Bounds on second generation scalar leptoquarks from the anomalous magnetic moment of the muon

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    We calculate the contribution of second generation scalar leptoquarks to the anomalous magnetic moment of the muon (AMMM). In the near future, E-821 at Brookhaven will reduce the experimental error on this parameter to Δaμexp<4×1010\Delta a_\mu^{\rm exp}<4\times 10^{-10}, an improvement of 20 over its current value. With this new experimental limit we obtain a lower mass limit of mΦL>186m_{\Phi_L}>186\ GeV for the second generation scalar leptoquark, when its Yukawa-like coupling λΦL\lambda_{\Phi_L}\ to quarks and leptons is taken to be of the order of the electroweak coupling g2g_2.Comment: 5 pages, plain tex, 1 figure (not included available under request

    Trapping dust particles in the outer regions of protoplanetary disks

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    In order to explain grain growth to mm sized particles and their retention in outer regions of protoplanetary disks, as it is observed at sub-mm and mm wavelengths, we investigate if strong inhomogeneities in the gas density profiles can slow down excessive radial drift and can help dust particles to grow. We use coagulation/fragmentation and disk-structure models, to simulate the evolution of dust in a bumpy surface density profile which we mimic with a sinusoidal disturbance. For different values of the amplitude and length scale of the bumps, we investigate the ability of this model to produce and retain large particles on million years time scales. In addition, we introduced a comparison between the pressure inhomogeneities considered in this work and the pressure profiles that come from magnetorotational instability. Using the Common Astronomy Software Applications ALMA simulator, we study if there are observational signatures of these pressure inhomogeneities that can be seen with ALMA. We present the favorable conditions to trap dust particles and the corresponding calculations predicting the spectral slope in the mm-wavelength range, to compare with current observations. Finally we present simulated images using different antenna configurations of ALMA at different frequencies, to show that the ring structures will be detectable at the distances of the Taurus Auriga or Ophiucus star forming regions.Comment: Pages 15, Figures 14. Accepted for publication in Astronomy and Astrophysic
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