The flavour projection of staggered fermions and the quarter-root trick

It is shown that the flavour projection of staggered fermions can be written as a projection between the fields on four separate, but parallel, lattices, where the fields on each are modified forms of the standard staggered fermion field. Because the staggered Dirac operator acts equally on each lattice, it respects this flavour projection. We show that the system can be gauged in the usual fashion and that this does not interfere with flavour projection. We also consider the path integral, showing that, prior to flavour projection, it evaluates to the same form on each lattice and that this form is equal to that used in the quarter-root trick. The flavour projection leaves a path integral for a single flavour of field on each lattice.Comment: 8 pages, including title pag

Excitations of torelon

The excitations of gluonic flux tube in a periodic lattice are examined. Monte Carlo simulations from an anisotropic lattice are presented and the comparison with effective string models is discussed.Comment: Talk at Lattice 2003; 3 pages, 4 figure

Effects of Surface Geology on Seismic Ground Motion Deduced from Ambient-Noise Measurements in the Town of Avellino, Irpinia Region (Italy)

The effects of surface geology on ground motion provide an important tool in seismic hazard studies. It is well known that the presence of soft sediments can cause amplification of the ground motion at the surface, particularly when there is a sharp impedance contrast at shallow depth. The town of Avellino is located in an area characterised by high seismicity in Italy, about 30 km from the epicentre of the 23 November 1980, Irpinia earthquake (M = 6.9). No earthquake recordings are available in the area. The local geology is characterised by strong heterogeneity, with impedance contrasts at depth. We present the results from seismic noise measurements carried out in the urban area of Avellino to evaluate the effects of local geology on the seismic ground motion. We computed the horizontal-to-vertical (H/V) noise spectral ratios at 16 selected sites in this urban area for which drilling data are available within the first 40 m of depth. A Rayleigh wave inversion technique using the peak frequencies of the noise H/V spectral ratios is then presented for estimating Vs models, assuming that the thicknesses of the shallow soil layers are known. The results show a good correspondence between experimental and theoretical peak frequencies, which are interpreted in terms of sediment resonance. For one site, which is characterised by a broad peak in the horizontal-to-vertical spectral-ratio curve, simple one-dimensional modelling is not representative of the resonance effects. Consistent variations in peak amplitudes are seen among the sites. A site classification based on shear-wave velocity characteristics, in terms of Vs30, cannot explain these data. The differences observed are better correlated to the impedance contrast between the sediments and basement. A more detailed investigation of the physical parameters of the subsoil structure, together with earthquake data, are desirable for future research, to confirm these data in terms of site response

Implication of Intestinal Barrier Dysfunction in Gut Dysbiosis and Diseases

The intestinal mucosal barrier, also referred to as intestinal barrier, is widely recognized as a critical player in gut homeostasis maintenance as it ensures the complex crosstalk between gut microbes (both commensals and pathogens) and the host immune system. Highly specialized epithelial cells constantly cope with several protective and harmful agents to maintain the multiple physiological functions of the barrier as well as its integrity. However, both genetic defects and environmental factors can break such equilibrium, thus promoting gut dysbiosis, dysregulated immune-inflammatory responses, and even the development of chronic pathological conditions. Here, we review and discuss the molecular and cellular pathways underlying intestinal barrier structural and functional homeostasis, focusing on potential alterations that may undermine this fine balance

The locality of the fourth root of staggered fermion determinant in the interacting case

The fourth root approximation in LQCD simulations with dynamical staggered fermions requires justification. We test its validity numerically in the interacting theory in a renormalization group framework.Comment: 6 pages, Talk presented at Lattice 2005 (Machines and Algorithms

Author Correction: High energy barriers for edge dislocation motion in body-centered cubic high entropy alloys (npj Computational Materials, (2021), 7, 1, (112), 10.1038/s41524-021-00577-7)

The original version of this Article contained an error in the Acknowledgements: ‘Project 200021_18198/1’ should have read ‘Project 200021_181987/1’. This has now been corrected in both the PDF and HTML versions of the Article

the role of human fatigue in the uncertainty of measurement

Abstract Risk of human error in measurement and testing is the result of the causal combination of factors and events that are involved in the process. This paper presents how to model technical and human errors and how these could interact in order to influences the reliability of measurement/test. Human errors were designed according with a System Dynamics approach with factors and states those are part of human's state and ability to handle with the process and procedures and instruments. Technical errors were related to the environment, its organization and suitability with standards. Human and Technical factors have been therefore integrated in order to predict states affecting the consistency of measure and uncertainty in range. Optimal combination of factors - based on a System Dynamics simulation and expert judgments - has been proposed according with a sampling analysis

High energy barriers for edge dislocation motion in body-centered cubic high entropy alloys

Recent theory proposes that edge dislocations in random body-centered cubic (BCC) high entropy alloys have high barriers for motion, conveying high strengths up to high temperatures. Here, the energy barriers for edge motion are computed for two model alloys, NbTaV and MoNbTaW as represented by interatomic potentials, using the Nudged Elastic Band method and compared to theoretical predictions. The average magnitude of the barriers and the average spacing of the barriers along the glide direction agree well with the analytical theory, with no adjustable parameters. The evolution of the barriers versus applied stress is modeled, and the mean strength is in reasonable agreement with the predicted zero-temperature strength. These findings validate the analytic theory. A reduced analytic model based on solute misfit volumes is then applied to Hf-Mo-Nb-Ta-Ti-Zr and Mo-Nb-Ta-Ti-V-W alloys, rationalizing the observed significant strength increases at room temperature and 1000 C-circle upon addition of solutes with large misfit into a base alloy. The analytic theory for edge motion is thus a powerful validated tool for guiding alloy selection

The Equation of State for QCD with 2+1 Flavors of Quarks

We report results for the interaction measure, pressure and energy density for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In our simulations we use a Symanzik improved gauge action and the Asqtad $O(a^2)$ improved staggered quark action for lattices with temporal extent $N_t=4$ and 6. The heavy quark mass $m_s$ is fixed at approximately the physical strange quark mass and the two degenerate light quarks have masses $m_{ud} =0.1m_s$ or $0.2m_s$. The calculation of the thermodynamic observables employs the integral method where energy density and pressure are obtained by integration over the interaction measure.Comment: 6 pages, 1 figure, 3 tables, contribution to the XXIIIrd International Symposium on Lattice Field Theory, 25-30 July 2005, Trinity College, Dublin, Irelan