Multi-mass solvers for lattice QCD on GPUs

Graphical Processing Units (GPUs) are more and more frequently used for lattice QCD calculations. Lattice studies often require computing the quark propagators for several masses. These systems can be solved using multi-shift inverters but these algorithms are memory intensive which limits the size of the problem that can be solved using GPUs. In this paper, we show how to efficiently use a memory-lean single-mass inverter to solve multi-mass problems. We focus on the BiCGstab algorithm for Wilson fermions and show that the single-mass inverter not only requires less memory but also outperforms the multi-shift variant by a factor of two.Comment: 27 pages, 6 figures, 3 Table

Absorption and wavepackets in optically excited semiconductor superlattices driven by dc-ac fields

Within the one-dimensional tight-binding minibands and on-site Coloumbic interaction approximation, the absorption spectrum and coherent wavepacket time evolution in an optically excited semiconductor superlattice driven by dc-ac electric fields are investigated using the semiconductor Bloch equations. The dominating roles of the ratios of dc-Stark to external ac frequency, as well as ac-Stark to external ac frequency, is emphasized. If the former is an integer ${\cal N}$, then also ${\cal N}$ harmonics are present within one Stark frequency, while the fractional case leads to the formation of excitonic fractional ladders. The later ratio determines the size and profile of the wavepacket. In the absence of excitonic interaction it controls the maximum size wavepackets reach within one cycle, while the interaction produces a strong anisotropy and tends to palliate the dynamic wavepacket localization.Comment: 14 pages, 7 postscript figure

Diagrammatic Quantum Monte Carlo for Two-Body Problem: Exciton

We present a novel method for precise numerical solution of the irreducible two-body problem and apply it to excitons in solids. The approach is based on the Monte Carlo simulation of the two-body Green function specified by Feynman's diagrammatic expansion. Our method does not rely on the specific form of the electron and hole dispersion laws and is valid for any attractive electron-hole potential. We establish limits of validity of the Wannier (large radius) and Frenkel (small radius) approximations, present accurate data for the intermediate radius excitons, and give evidence for the charge transfer nature of the monopolar exciton in mixed valence materials.Comment: 4 pages, 5 figure

Haematopinus Infestations and Mycoplasma Infections of Water Buffalo (Bubalus bubalis) Herds in National Parks of Hungary

The biology, epidemiology and pathology of sucking louse infestation and Mycoplasma infection of water buffalo (Bubalus bubalis) herds in Hungarian national parks were studied between 19 December 2011 and 4 May 2012. A total of 333 water buffaloes were examined in buffalo stocks of the Balaton Uplands, Fertő-Hanság and Kiskunság National Parks. The objective was to determine the prevalence and rate of sucking louse infestation and mycoplasma infection among water buffaloes. Always an area of identical size (2 cm2) was examined on the right or left side of the middle part of the animals' neck. A total of 3106 eggs, 10 nymphs and 105 adults of the sucking louse Haematopinus tuberculatus were identified with the help of a Conrad USB microscopic camera and a Wild-Leitz-Leica M420 photomacroscope. The data were evaluated using the Quantitative Parasitology software QP 3.0. The prevalence of mycoplasmas was determined in 20 randomly selected buffaloes of two national parks with the help of sterile nasal and vaginal transport swabs (Sarstedt). All of the 10 nasal swabs collected from buffaloes in the Balaton Uplands National Park contained Mycoplasma bovirhinis and three swab samples yielded M. bovis as well. Mycoplasma bovirhinis was cultured from 8 out of 10 swabs taken from the vagina, and three vaginal samples also yielded M. bovis. Similar results were obtained by testing samples collected from buffaloes in the Kiskunság National Park (Mórahalom). All ten nasal swab samples yielded M. bovirhinis. From two samples a mixture of M. bovirhinis and M. bovis was cultured. Nine out of the 10 vaginal swabs yielded M. bovirhinis while two showed a combined infection by M. bovis and M. bovirhinis

Light Hadron Masses from Lattice QCD

This article reviews lattice QCD results for the light hadron spectrum. We give an overview of different formulations of lattice QCD, with discussions on the fermion doubling problem and improvement programs. We summarize recent developments in algorithms and analysis techniques, that render calculations with light, dynamical quarks feasible on present day computer resources. Finally, we summarize spectrum results for ground state hadrons and resonances using various actions.Comment: 53 pages, 24 figures, one table; Rev.Mod.Phys. (published version); v2: corrected typ

The authorial delusion: counting lady Macbeth’s children

In 1933, literary critic L. C. Knights published a caustic essay against the notion cultivated by certain of his colleagues, predominantly A. C. Bradley, that Shakespeare is a ‘great creator of characters’. Knights (1973) regarded the examination of isolated particles such as ‘character’ as disorientating, alleging that an analysis of this sort obscures the greater merit of language. Knight’s polemic essentially stands in the threshold of the dissention between formalists and realists: the former consider the examination of the fictional narrative as anything but a textual construct a scholarly faux pas; the latter regard the referential relationship between text and the world as a foundation for the creation of fiction. This is a pseudo-dilemma. The notion that literature is denuded of its artistic merit once it is defined by its constituent artefacts is disorienting, for it completely bypasses the dynamics of its creation. Put differently, a post-event analysis can exist as a standalone act, albeit it cannot challenge or dismiss the foundational principles of the event’s creation process

Ethical preferences for influencing superiors: A 41-society study

With a 41-society sample of 9990 managers and professionals, we used hierarchical linear modeling to investigate the impact of both macro-level and micro-level predictors on subordinate influence ethics. While we found that both macro-level and micro-level predictors contributed to the model definition, we also found global agreement for a subordinate influence ethics hierarchy. Thus our findings provide evidence that developing a global model of subordinate ethics is possible, and should be based upon multiple criteria and multilevel variables