968 research outputs found

    Neutrino speed anomaly as signal of Lorentz violation

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    We make a reanalysis on the issue of neutrino speed anomaly by taking into account the newly reported data from the ICARUS experiment and other CNGS collaborations. We examine the consequence of the Lorentz violation on the neutrino speed in a new framework of standard model supplement (SMS), and find that the Lorentz violating parameters are constrained at least one order stronger than that of the earlier OPERA report. The combination with other phenomenological considerations puts more stringent constraints on the Lorentz violation of neutrinos.Comment: 14 pages. Significantly improved version with updated analysis on the relevant experiments related to neutrino speed. Matches to the final published versio

    A Theoretical Diagnosis on Light Speed Anisotropy from GRAAL Experiment

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    The light speed anisotropy, i.e., the variation of the light speed with respect to the direction in an "absolute" reference frame, is a profound issue in physics. The one-way experiment, performed at the GRAAL facility of the European Synchrotron Radiation Facility (ESRF) in Grenoble, reported results on the light speed anisotropy by Compton scattering of laser photons on high-energy electrons. So far, most articles concerned with the GRAAL data have established only the upper bounds on the anisotropy parameters based on available theories. We use a new theory of the Lorentz invariance violation to analyse the available GRAAL data and obtain the stringent upper limit of the order 2.4×10−142.4\times10^{-14} on the Lorentz violation parameters. In the meantime, we also can reproduce the allowed light speed anisotropy appearing in the azimuthal distribution of the GRAAL experimental data, and find that the best-fit parameters are compatible with the competitive upper bounds.Comment: 13 pages, 2 figures, final version in journal publicatio

    Lorentz Violation of the Photon Sector in Field Theory Models

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    We compare the Lorentz violation terms of the pure photon sector between two field theory models, namely the minimal standard model extension (SME) and the standard model supplement (SMS). From the requirement of the identity of the intersection for the two models, we find that the free photon sector of the SMS can be a subset of the photon sector of the minimal SME. We not only obtain some relations between the SME parameters, but also get some constraints on the SMS parameters from the SME parameters. The CPT-odd coefficients (kAF)α(k_{AF})^{\alpha} of the SME are predicted to be zero. There are 15 degrees of freedom in the Lorentz violation matrix Δαβ\Delta^{\alpha\beta} of free photons of the SMS related with the same number of degrees of freedom in the tensor coefficients (kF)αβμν(k_F)^{\alpha\beta\mu\nu}, which are independent from each other in the minimal SME, but are inter-related in the intersection of the SMS and the minimal SME. With the related degrees of freedom, we obtain the conservative constraints (2σ2\sigma) on the elements of the photon Lorentz violation matrix. The detailed structure of the photon Lorentz violation matrix suggests some applications to the Lorentz violation experiments for photons.Comment: 9 pages, no figure, three tables. Final version for journal publicatio

    AMG: Automated Efficient Approximate Multiplier Generator for FPGAs via Bayesian Optimization

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    Approximate computing is a promising approach to reduce the power, delay, and area in hardware design for many error-resilient applications such as machine learning (ML) and digital signal processing (DSP) systems, in which multipliers usually are key arithmetic units. Due to the underlying architectural differences between ASICs and FPGAs, existing ASIC-based approximate multipliers do not offer symmetrical gains when they are implemented by FPGA resources. In this paper, we propose AMG, an open-source automated approximate multiplier generator for FPGAs driven by Bayesian optimization (BO) with parallel evaluation. The proposed method simplifies the exact half adders (HAs) for the initial partial product (PP) compression in a multiplier while preserving coarse-grained additions for the following accumulation. The generated multipliers can be effectively mapped to lookup tables (LUTs) and carry chains provided by modern FPGAs, reducing hardware costs with acceptable errors. Compared with 1167 multipliers from previous works, our generated multipliers can form a Pareto front with 28.70%-38.47% improvements in terms of the product of hardware cost and error on average. All source codes, reproduced multipliers, and our generated multipliers are available at https://github.com/phyzhenli/AMG.Comment: 7 pages, 2023 IEEE International Conference on Field-Programmable Technology (ICFPT

    P38 Plays an Important Role in Glucolipotoxicity-Induced Apoptosis in INS-1 Cells

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    Objectives. The mechanism underlying the regulation of glucolipotoxicity-induced apoptosis by MAPKs was examined in INS-1 cells. Methods. The rat insulinoma cell line INS-1 was cotreated with glucose (30 mM) and palmitic acid (0.2 mM) (GLU+PA). Apoptosis was assessed by cell morphology and detection of PARP cleavage. The activation of MAPKs was examined by Western blotting using specific antibodies against the phosphorylated forms of JNK, ERK1/2, and P38. Results. (1) Live cell imaging studies showed that treatment with GLU+PA for 72 h induced significant cell death, concomitant with PARP-1 cleavage and caspase-3 activation, which peaked at 96 h of treatment. (2) Western blot analysis of the activation of MAPKs during GLU+PA-induced INS-1 cell apoptosis showed that phosphorylation of P38 increased gradually and reached a peak at 96 h, which coincided with PARP-1 cleavage. A transient increase of ERK activation was followed by a rapid decline at 96 h, whereas JNK phosphorylation status remained unchanged in response to GLU+PA. (3) Phosphorylation of insulin receptor substrate (IRS)-2 at 48 h of treatment triggered its degradation, which coincided with P38 activation. (4) Inhibition of P38, but not JNK or ERK, blocked GLU+PA-induced INS-1 cell apoptosis. Conclusions. P38 may be involved in the regulation of glucolipotoxicity-induced apoptosis through the phosphorylation of IRS-2

    Fast Adjustable NPN Classification Using Generalized Symmetries

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    NPN classification of Boolean functions is a powerful technique used in many logic synthesis and technology mapping tools in FPGA design flows. Computing the canonical form of a function is the most common approach of Boolean function classification. In this paper, a novel algorithm for computing NPN canonical form is proposed. By exploiting symmetries under different phase assignments and higher-order symmetries of Boolean functions, the search space of NPN canonical form computation is pruned and the runtime is dramatically reduced. The algorithm can be adjusted to be a slow exact algorithm or a fast heuristic algorithm with lower quality. For exact classification, the proposed algorithm achieves a 30× speedup compared to a state-of-the-art algorithm. For heuristic classification, the proposed algorithm has similar performance as the state-of-the-art algorithm with a possibility to trade runtime for quality

    The influence of crystal chemistry on lithium isotopic fractionation in pegmatite minerals

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    The understanding of lithium (Li) isotopic fractionation controlled by mineral species, especially those containing trace or minor amounts of Li (e.g., a few to tens of ppm), is hindered by lack of knowledge about the crystal chemistry of Li-bearing minerals. In this study, we performed solid-state Nuclear Magnetic Resonance (NMR) experiments, employing the Li7 Magic Angle Spinning (MAS) to investigate the local coordination environments of Li in minerals and their impact on Li isotopic fractionation. Our investigation focused on four coexisting minerals sourced from the Koktokay No. 3 pegmatite dike in the Xinjiang, China, namely quartz, K-feldspar, muscovite, and tourmaline, which has Li content and δLi7 value of 14.6 ppm and 3.90‰, 19.3 ppm and 7.09‰, 430 ppm and − 14.2‰, and 108 ppm and 13.42‰, respectively. Muscovite displayed the lowest δLi7 value, whereas tourmaline exhibited the highest value, and a considerable variation of 27.62‰ in δLi7 value was observed between muscovite and tourmaline. The analysis of Li7 MAS-NMR spectra further revealed distinct Li coordination environments among these minerals. A notable counterintuitive negative correlation exists between the δLi7 value and the chemical shift for the four Li-bearing minerals. This negative correlation contrasts to the expected Li isotopic fractionation under equilibrium conditions, in which enrichment of heavy Li isotopes is accompanied with large chemical shifts in Li-bearing minerals. This unexpected observation can be potentially attributed to nonequilibrium conditions of crystallization of the investigated minerals, coupled with fast diffusion of Li6 in minerals, boasting abnormally high coordination numbers due to weak Li[sbnd]O chemical bonds. Essentially, our study suggests that Li isotopic fractionation among Li-bearing minerals in pegmatite can be significant and is intricately influenced by both crystal chemistry and chemical diffusion.</p

    Isolation and Functional Characterization of an AGAMOUS-LIKE 18 (AGL18) MADS-box Gene from Cucumber (Cucumis sativus L.)

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    MADS-box proteins play vital roles in plant growth and development. However, few studies have addressed the biological functions of MADS-box genes in cucumber. In this study, a MADS-box gene, CsMADS25, was cloned from cucumber (Cucumis sativus L.). The open reading frame (ORF) of CsMADS25 was 810 bp in length and encoded a deduced protein consisting of 269 amino acids with a calculated MW of 30.53 kDa and a theoretical pI of 5.38. Sequence alignment showed that CsMADS25 shared the highest amino acid identity with CmMADS09 from Cucumis melo. Phylogenetic tree analysis indicated that CsMADS25 was clustered with AGL18 proteins with high bootstrap values. qRT-PCR analysis showed that the expression of CsMADS25 was observably regulated by various abiotic stresses and GAtreatments. Overexpression of CsMADS25 resulted in dwarf and small-leaf phenotypes in transgenic Arabidopsis plants, and the leaf index value (leaf length/width ratio) of transgenic plants was dramatically increased compared with that of wild-type (WT) plants. These findings suggest that CsMADS25 might play important roles in various developmental processes and in response to abiotic stress of cucumber
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