Decay channels and charmonium mass-shifts

The discovery in the last few years of the $X, Y$ and $Z$ states of the extended charmonium family has highlighted the importance of the closeness of decay channels to an understanding of these mesons. We aid this debate by illustrating a simple calculational procedure for including the effect of open and nearby closed channels.Comment: 4 pages, 2 figures Revised version: (1) corrected 2 typos in Table II, (2) additional text in penultimate paragraph to clarify the calculation of mass-shifts for $\eta_c'$ and $\eta_c"$. We thank colleagues for pointing out confusing wording of previous tex

Visual Communications on the Road in Arkansas: Analysis of Secondary Students Videos

In the summer of 2010, the Visual Communications on the Road in Arkansas: Creative Photo and Video Projects to Promote Agriculture program was initiated. The program consisted of a two-week agricultural communications curriculum that would be taught by agricultural science teachers in Arkansas. The curriculum was composed of lessons about photography, writing, and videography, and the program introduced students to digital photography and videography equipment and the proper uses of equipment. Once the curriculum was taught in secondary schools, a mobile classroom unit—consisting of a travel trailer, photography and videography equipment, and laptop computers equipped with editing software—would visit the school to assist students with the creation of short promotional videos about agriculture. The student-created videos were used as a hands-on extension of the curriculum learned in the classroom. Completed videos were posted to YouTube and then analyzed to assess student application of competencies taught in the curriculum. The researchers created a coding sheet to systematically assess all posted videos and inter- and intrarater reliability was maintained. An analysis of data gathered from the video assessment showed that secondary students were able to effectively apply many of the techniques taught in the curriculum through the agricultural videos created. Additional findings and recommendations for application and future research are presented

Structure of the lightest scalar meson from the 1/Nc expansion of Unitarized Chiral Perturbation Theory and Regge Theory

One-loop unitarized Chiral Perturbation Theory (UChPT) calculations, suggest a different Nc behaviour for the sigma or f_0(600) and rho(770) mesons: while the rho meson becomes narrower with Nc, as is expected for a q-qbar meson, the sigma becomes broader, and its contribution to the total cross section is less and less important. On the other hand, local duality requires a cancellation between the sigma and rho amplitudes, but if there is a different Nc behaviour for them, there is a possible contradiction between the Inverse Amplitude Method (IAM) and local duality for large Nc. However, next to next to leading order UChPT calculations suggested a subdominant q-qbar component for the sigma with a mass around 1.2 GeV. In this work, we show that this subdominant q-qbar component is indeed needed to ensure local duality.Comment: To appear in the Proceedings of the Hadron09 International Conference. 29th Nov-4th Dec. 2009. Tallahassee, FL, USA. 5 page

Human activity was a major driver of the mid-Holocene vegetation change in southern Cumbria: Implications for the elm decline in the British Isles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The dramatic decline in elm (Ulmus) across a large swathe of north-west Europe in the mid-Holocene has been ascribed to a number of possible factors, including climate change, human activity and/or pathogens. A major limitation for identifying the underlying cause(s) has been the limited number of high-resolution records with robust geochronological frameworks. Here, we report a multiproxy study of an upland (Blea Tarn) and lowland (Urswick Tarn) landscape in southern Cumbria (British Isles) to reconstruct vegetation change across the elm decline in an area with a rich and well-dated archaeological record to disentangle different possible controls. Here we find a two-stage decline in Ulmus taking place between 6350–6150 and 6050–5850 cal a BP, with the second phase coinciding with an intensification of human activity. The scale of the decline and associated human impact is more abrupt in the upland landscape. We consider it likely that a combination of human impact and disease drove the Ulmus decline within southern Cumbria.This work was funded by a studentship for MJG from the University of Exeter and Sir John Fisher Foundation. Additional funding for 14C dating was from the Cumberland and Westmorland Antiquarian and Archaeological Society (Clare Fell Bursary to MJG), and the Australian Research Council (FL100100195)

Sonoma Persistent Surveillance System

Sonoma offers the first cost-effective, broad-area, high-resolution, real-time motion imagery system for surveillance applications. Sonoma is unique in its ability to provide continuous, real-time video imagery of an area the size of a small city with resolutions sufficient to track 8,000 moving objects in the field of view. At higher resolutions and over smaller areas, Sonoma can even track the movement of individual people. The visual impact of the data available from Sonoma is already causing a paradigm shift in the architecture and operation of other surveillance systems. Sonoma is expected to cost just one-tenth the price of comparably sized sensor systems. Cameras mounted on an airborne platform constantly monitor an area, feeding data to the ground for real-time analysis. Sonoma was designed to provide real-time data for actionable intelligence in situations such as monitoring traffic, special events, border security, and harbors. If a Sonoma system had been available in the aftermath of the Katrina and Rita hurricanes, emergency responders would have had real-time information on roads, water levels, and traffic conditions, perhaps saving many lives

Location, correlation, radiation: where is the σ\sigma, what is its structure and what is its coupling to photons?

Scalar mesons are a key expression of the infrared regime of QCD. The lightest of these is the $\sigma$. Now that its pole in the complex energy plane has been precisely located, we can ask whether this state is transiently ${\bar q}q$ or ${\bar {qq}} qq$ or a multi-meson molecule or largely glue? The two photon decay of the $\sigma$ can, in principle, discriminate between these possibilities. We review here how the $\gamma\gamma\to\pi^+\pi^-$, $\pi^0\pi^0$ cross-sections can be accurately computed. The result not only agrees with experiment, but definitively fixes the radiative coupling of the $\sigma$. This equates to a two photon width of $(4.1 \pm 0.3)$ keV, which accords with the simple non-relativistic quark model expectation for a ${\bar u}u, {\bar d}d$ scalar. Nevertheless, robust predictions from relativistic strong coupling QCD are required for each of the possible compositions before we can be sure which one really delivers the determined $\gamma\gamma$ coupling.Comment: 18 pages, 11 figures. To be published in Modern Physics Letters A A number of references updated and three sentences changed in the text to reflect thes

Temperature Dependence of the Cu(2) NQR Line Width in YBa2_2Cu3_3O7−y_{7-y}

Systematic measurements of the $^{63}$Cu(2) NQR line width were performed in underdoped YBa$_2$Cu$_3$O$_{7-y}$ samples over the temperature range 4.2 K $<T<300$ K. It was shown that the copper NQR line width monotonically increases upon lowering temperature in the below-critical region, resembling temperature behavior of the superconducting gap. The observed dependence is explained by the fact that the energy of a condensate of sliding charge-current states of the charge-density-wave type depends on the phase of order parameter. Calculations show that this dependence appears only at $T<T_c$. Quantitative estimates of the line broadening at $T<T_c$ agree with the measurement results.Comment: 4 pages, 2 figure