Technology and manufacturing in the seventh district

Technology ; Federal Reserve District, 7th ; Manufactures - North Central states

On the Definition of Gauge Field Operators in Lattice Gauge-Fixed Theories

We address the problem of defining the gauge four-potential on the lattice, in terms of the natural link variables. Different regularized definitions are shown, through non perturbative numerical computation, to converge towards the same continuum renormalized limit.Comment: 8 pages, LaTeX2e/LaTeX209, 3 eps figure

Reform for Midwest urban schools--conference summary

Education - Middle West - Chicago (Ill.)

Emerging urban markets in the Midwest

Chicago (Ill.) ; Community development ; Middle West

The binational Great Lakes economy

Great Lakes ; North American Free Trade Agreement ; Canada ; Manufactures

X-ray Flares of EV Lac: Statistics, Spectra, Diagnostics

We study the spectral and temporal behavior of X-ray flares from the active M-dwarf EV Lac in 200 ks of exposure with the Chandra/HETGS. We derive flare parameters by fitting an empirical function which characterizes the amplitude, shape, and scale. The flares range from very short (<1 ks) to long (10 ks) duration events with a range of shapes and amplitudes for all durations. We extract spectra for composite flares to study their mean evolution and to compare flares of different lengths. Evolution of spectral features in the density-temperature plane shows probable sustained heating. The short flares are significantly hotter than the longer flares. We determined an upper limit to the Fe K fluorescent flux, the best fit value being close to what is expected for compact loops.Comment: 9 pages; 9 figures; latex/emulateapj style; Submitted to The Astrophysical Journa

Bright hot impacts by erupted fragments falling back on the Sun: magnetic channelling

Dense plasma fragments were observed to fall back on the solar surface by the Solar Dynamics Observatory after an eruption on 7 June 2011, producing strong EUV brightenings. Previous studies investigated impacts in regions of weak magnetic field. Here we model the $\sim~300$ km/s impact of fragments channelled by the magnetic field close to active regions. In the observations, the magnetic channel brightens before the fragment impact. We use a 3D-MHD model of spherical blobs downfalling in a magnetized atmosphere. The blob parameters are constrained from the observation. We run numerical simulations with different ambient density and magnetic field intensity. We compare the model emission in the 171\AA~ channel of the Atmospheric Imaging Assembly with the observed one. We find that a model of downfall channelled in a $\sim~1$MK coronal loop confined by a magnetic field of $\sim~10-20$G, best explains qualitatively and quantitatively the observed evolution. The blobs are highly deformed, further fragmented, when the ram pressure becomes comparable to the local magnetic pressure and they are deviated to be channelled by the field, because of the differential stress applied by the perturbed magnetic field. Ahead of them, in the relatively dense coronal medium, shock fronts propagate, heat and brighten the channel between the cold falling plasma and the solar surface. This study shows a new mechanism which brightens downflows channelled by the magnetic field, such as in accreting young stars, and also works as a probe of the ambient atmosphere, providing information about the local plasma density and magnetic field.Comment: 17 pages, 14 figure

qqˉq\bar{q}-potential: a numerical study

We report the results of recent lattice simulations aimed at computing the $q$ and $\bar q$ potential energies in the singlet and the octet (adjoint) representation.Comment: 7 pages, 4 figures, poster presented at the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German

The extended structure of the dwarf irregular galaxy Sagittarius

We present a detailed study of the stellar and HI structure of the dwarf irregular galaxy Sagittarius. We use new deep and wide field photometry to trace the surface brightness profile of the galaxy out to ~5.0' (corresponding to ~1600 pc) and down to $\mu_V\simeq 30.0$ mag/arcsec$^2$, thus showing that the stellar body of the galaxy is much more extended than previously believed, and it is similarly (or more) extended than the overall HI distribution. The whole major-axis profile is consistent with a pure exponential, with a scale radius of $\simeq 340$ pc. The surface density maps reveal that the distribution of old and intermediate-age stars is smooth and remarkably flattened out to its edges, while the associated HI has a much rounder shape, is off-centred and presents multiple density maxima and a significant hole. No clear sign of systemic rotation is detectable in the complex HI velocity field. No metallicity gradient is detected in the old and intermediate age population of the galaxy, and we confirm that this population has a much more extended distribution than young stars (age$\lt 1$ Gyr).Comment: 11 pages, 14 figures, accepted for publication on A&A. arXiv admin note: text overlap with arXiv:1404.169