Chiral Perturbation Theory and Finite Size Effects on the Nucleon Mass in unquenched QCD

We calculate finite size effects on nucleon masses in chiral perturbation theory. We confront the theoretical predictions with N_f=2 lattice results and discuss chiral extrapolation formulae.Comment: talk at Lattice 03 (spectrum), 3 pages latex, 3 figures. Assignment of 2 data points to incorrect data sets in plot 1 and of 1 data point in plot 2 corrected. 1 fm lattice result updated. Conclusions unchange

The Nambu-Jona-Lasinio model with staggered fermions

We investigate the neighbourhood of the chiral phase transition in a lattice Nambu--Jona-Lasinio model, using both Monte Carlo methods and lattice Schwinger-Dyson equations.Comment: Talks at LAT93, Dallas, U.S.A. Postscript file, 6 pages, figures include

Productivity Constraints of Cholistani Farmers

This paper examines the factors behind low crop yield in Cholistan. Both the quantitative and qualitative analysis show how the low levels of agricultural productivity in this area may be linked to material and climatic factors. The quantitative analysis is mainly focused on physical factors. The qualitative analysis, however, emphasises that relative inefficiency of agricultural activity in Cholistan reflects the influence of physical, economic, social and, most importantly, climatic factors. The quantitative findings provide valuable insight into various ‘sources of productivity’ in terms of acreage effect, capital input effect and irrigation water availability effect. The size of the positive and significant coefficients on these variables suggest the extent to which one or the other variable effect is prominent in improving the crop yield. The qualitative analysis examines multiple interrelated factors which can be blamed on for relative inefficiency of Cholistani farmers. The hot climate of the area turns out to be the most critical variable in this analysis. Many specific technological drought-mitigating measures are proposed. However, for consistent policy formulation, a thorough study and quantitative evaluation of the potential and practicality of these measures in Cholistan is suggested.

Gauge invariant generalization of the 2D chiral Gross-Neveu model

By means of the Lee-Shrock transformation we generalize the 2D Gross-Neveu (GN$_2$) model to a U(1) gauge theory with charged fermion and scalar fields in 2D ($\chi U \phi_2$ model). The $\chi U \phi_2$ model is equivalent to the GN$_2$ model at infinite gauge coupling. We show that the dynamical fermion mass generation and asymptotic freedom in the effective four-fermion coupling persist also when the gauge coupling decreases. These phenomena are not influenced by the XY$_2$ model phase transition at weak coupling. This suggests that the $\chi U \phi_2$ model is in the same universality class as the GN$_2$ model and thus renormalizable.Comment: Contribution to Lattice 95, LaTeX file (4 pages), 4 ps-figures appended (uuencoded), abstract correcte

Assessing the Reliability of Template-Based Clustering for Tractography in Healthy Human Adults

Tractography is a non-invasive technique to investigate the brain’s structural pathways (also referred to as tracts) that connect different brain regions. A commonly used approach for identifying tracts is with template-based clustering, where unsupervised clustering is first performed on a template in order to label corresponding tracts in unseen data. However, the reliability of this approach has not been extensively studied. Here, an investigation into template-based clustering reliability was performed, assessing the output from two datasets: Human Connectome Project (HCP) and MyConnectome project. The effect of intersubject variability on template-based clustering reliability was investigated, as well as the reliability of both deep and superficial white matter tracts. Identified tracts were evaluated by assessing Euclidean distances from a dataset-specific tract average centroid, the volumetric overlap across corresponding tracts, and along-tract agreement of quantitative values. Further, two template-based techniques were employed to evaluate the reliability of different clustering approaches. Reliability assessment can increase the confidence of a tract identifying technique in future applications to study pathways of interest. The two different template-based approaches exhibited similar reliability for identifying both deep white matter tracts and the superficial white matter

HUNTING PHENOMENON STUDY OF RAILWAY CONVENTIONAL TRUCK ON TANGENT TRACKS DUE TO CHANGE IN RAIL WHEEL GEOMETRY

A mathematical dynamic model of railway conventional truck is presented with 12 degrees of freedom equations of motion. The presented dynamic system consists of conventional truck attached with two single wheelsets in which equipped with lateral, longitudinal and vertical linear stiffness and damping primary and secondary suspensions. This investigated model governs lateral displacement, vertical displacement, roll yaw angles of each of wheelset and the lateral displacement, vertical displacement, roll and yaw angle of conventional truck. Kalker's linear theory has been adopted to evaluate the creep forces which are introduced on rail wheels due to rail wheel contact. The railway truck mathematical equations of motion are solved using fourth order Rung-Kutta method which requires that differential equations to be transformed into a set of first order differential equations. The transformed state space equations are simulated with computer aided simulation to represent the dynamic behavior and time solution of dynamics of conventional truck moving on tangent tracks. Influences of the geometric parameters of the rail wheel such as wheel conicity and nominal rolling radius on the dynamic stability of the system are investigated. It is concluded that the geometric parameters of the rail wheel have different effects on the hunting instability and on the change of the critical hunting velocity of the system. In addition critical hunting velocity of rail trucks is proportional inversely with the square roots of wheel conicity but high critical hunting velocity obtained by increasing the nominal rolling radius of the rail wheel

Determination of Light and Strange Quark Masses from Full Lattice QCD

We compute the light and strange quark masses m_l = (m_u+m_d)/2 and m_s, respectively, in full lattice QCD with N_f=2 flavors of light dynamical quarks. The renormalization constants, which convert bare quark masses into renormalized quark masses, are computed nonperturbatively, including the effect of quark-line disconnected diagrams. We obtain m_l=4.7(2)(3) MeV and m_s=119(5)(8) MeV in the MSbar scheme at the scale 2 GeV.Comment: 7 pages, 8 figure