6,606 research outputs found
Evidence for new unidentified TeV gamma-ray sources from angularly-correlated hot-spots observed by independent TeV gamma-ray sky surveys
We have examined the directional cross-correlation of statistical `hot-spots'
between a Northern Sky TeV Gamma Ray Survey by the Milagro Observatory and a
similar survey by the Tibet Array. We find the directions of these hot-spots
are angularly uncorrelated between the two surveys for large angular
separations (Delta theta > 4 degrees), but there appears to be a statistically
significant correlation between hot-spot directions for Delta theta < 1.5
degrees. Independent simulations indicate the chance probability for the
occurrence of this correlation is approximately 10^-4, implying the existence
of one or more previously unobserved TeV gamma-ray sources in these directions.
The data sets are consistent with both point-like sources or diffuse sources
with extent of 1 - 2 degrees.Comment: 12 pages, 2 figures, 3 tables. Submitted to Astrophysical Journal
Letter
An optimal controller based on linear approximation of an acoustical test facility, part B Final report
Optimal digital controller based on linear approximation of acoustical test facility, for determining effects of supersonic rocket engine noise on vehicle surfac
A study of poultry processing plant noise characteristics and potential noise control techniques
The noise environment in a typical poultry processing plant was characterized by developing noise contours for two representative plants: Central Soya of Athens, Inc., Athens, Georgia, and Tip Top Poultry, Inc., Marietta, Georgia. Contour information was restricted to the evisceration are of both plants because nearly 60 percent of all process employees are stationed in this area during a normal work shift. Both plant evisceration areas were composed of tile walls, sheet metal ceilings, and concrete floors. Processing was performed in an assembly-line fashion in which the birds travel through the area on overhead shackles while personnel remain at fixed stations. Processing machinery was present throughout the area. In general, the poultry processing noise problem is the result of loud sources and reflective surfaces. Within the evisceration area, it can be concluded that only a few major sources (lung guns, a chiller component, and hock cutters) are responsible for essentially all direct and reverberant sound pressure levels currently observed during normal operations. Consequently, any effort to reduce the noise problem must first address the sound power output of these sources and/or the absorptive qualitities of the room
Brane world models need low string scale
Models with large extra dimensions offer the possibility of the Planck scale being of order the electroweak scale, thus alleviating the gauge hierarchy problem. We show that these models suffer from a breakdown of unitarity at around three quarters of the low effective Planck scale. An obvious candidate to fix the unitarity problem is string theory. We therefore argue that it is necessary for the string scale to appear below the effective Planck scale and that the first signature of such models would be string resonances. We further translate experimental bounds on the string scale into bounds on the effective Planck scale
Influence of Logging on Douglas Fir Beetle Populations
All species of bark beetles of economic importance prefer to attack freshly-killed host material. Logging slash, wind-throw, and fire-killed timber provide ideal breeding grounds for bark beetles. A few species, mostly in the Dendroctonus group, are able to kill living trees. When beetles in the group, raised in preferred host material, cannot find any or enough freshly-killed trees, logs, or slash to enter, they may attack living trees. In the interior of British Columbia, infestations of the Douglas fir beetle can often be traced to logging disturbance
Making music for mental health: how group drumming mediates recovery
BACKGROUND: While music-making interventions are increasingly recognised as enhancing mental health, little is known of why music may engender such benefit. The objective of this article is to elucidate the features of a programme of group drumming known to enable mental health recovery. METHODS: Qualitative research was conducted with 39 mental health patients and carers who had demonstrated recovery following engagement with a programme of group djembe drumming in the UK. Data were collected through semi-structured individual interviews and focus group interviews designed to understand the connection between drumming and recovery and analysed using Interpretative Phenomenological Analysis (IPA). RESULTS: Results revealed three overarching features of the drumming intervention: (1) the specific features of drumming, including drumming as a form of non-verbal communication, as a connection with life through rhythm, and as a grounding experience that both generates and liberates energy; (2) the specific features of the group, including the group as a space of connection in and through the rhythmic features of the drumming, as well as facilitating feelings of belonging, acceptance, safety and care, and new social interactions; (3) the specific features of the learning, including learning as an inclusive activity in which the concept of mistakes is dissolved and in which there is musical freedom, supported by an embodied learning process expedited by the musical facilitator. CONCLUSION: The findings provide support for the conceptual notion of 'creative practice as mutual recovery', demonstrating that group drumming provides a creative and mutual learning space in which mental health recovery can take place
Kinetic Energy Density Study of Some Representative Semilocal Kinetic Energy Functionals
There is a number of explicit kinetic energy density functionals for
non-interacting electron systems that are obtained in terms of the electron
density and its derivatives. These semilocal functionals have been widely used
in the literature. In this work we present a comparative study of the kinetic
energy density of these semilocal functionals, stressing the importance of the
local behavior to assess the quality of the functionals. We propose a quality
factor that measures the local differences between the usual orbital-based
kinetic energy density distributions and the approximated ones, allowing to
ensure if the good results obtained for the total kinetic energies with these
semilocal functionals are due to their correct local performance or to error
cancellations. We have also included contributions coming from the laplacian of
the electron density to work with an infinite set of kinetic energy densities.
For all the functionals but one we have found that their success in the
evaluation of the total kinetic energy are due to global error cancellations,
whereas the local behavior of their kinetic energy density becomes worse than
that corresponding to the Thomas-Fermi functional.Comment: 12 pages, 3 figure
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