709 research outputs found
Swain Committee Report
Letter addressed to the Secretary of the Navy, the Honorable Josephus H. Daniels, from the Committee appointed by the President of the Society for the Promotion of Engineering Education, to visit the U.S. Naval Academy in Annapolis, MD. The purpose was to evaluate the work of the Post Graduate School. The committee recommended enlarging the enrollment of the Post Graduate School and providing for appropriate funding for buildings, equipment and curricula
Toxicology and Epidemiology: Improving the Science with a Framework for Combining Toxicological and Epidemiological Evidence to Establish Causal Inference
Historically, toxicology has played a significant role in verifying conclusions drawn on the basis of epidemiological findings. Agents that were suggested to have a role in human diseases have been tested in animals to firmly establish a causative link. Bacterial pathogens are perhaps the oldest examples, and tobacco smoke and lung cancer and asbestos and mesothelioma provide two more recent examples. With the advent of toxicity testing guidelines and protocols, toxicology took on a role that was intended to anticipate or predict potential adverse effects in humans, and epidemiology, in many cases, served a role in verifying or negating these toxicological predictions. The coupled role of epidemiology and toxicology in discerning human health effects by environmental agents is obvious, but there is currently no systematic and transparent way to bring the data and analysis of the two disciplines together in a way that provides a unified view on an adverse causal relationship between an agent and a disease. In working to advance the interaction between the fields of toxicology and epidemiology, we propose here a five-step "Epid-Toxâ process that would focus on: (1) collection of all relevant studies, (2) assessment of their quality, (3) evaluation of the weight of evidence, (4) assignment of a scalable conclusion, and (5) placement on a causal relationship grid. The causal relationship grid provides a clear view of how epidemiological and toxicological data intersect, permits straightforward conclusions with regard to a causal relationship between agent and effect, and can show how additional data can influence conclusions of causalit
The Perturbative Pole Mass in QCD
It is widely believed that the pole mass of a quark is infrared-finite and
gauge-independent to all orders in perturbation theory. This seems not to have
been proved in the literature. A proof is provided here.Comment: 12 pages REVTeX with 2 figures; archiving published version with note
and references added. If you thought this was proven long ago see
http://www-theory.fnal.gov/people/ask/TeX/mPole
Brane Cosmology in the Background of D-Brane with NS B Field
We study the cosmological evolution of the four-dimensional universe on the
probe D3-brane in geodesic motion in the curved background of the source
Dp-brane with non-zero NS B field. The Friedman equations describing the
expansion of the brane universe are obtained and analyzed for various limits.
We elaborate on corrections to the cosmological evolution due to nonzero NS B
field.Comment: 13 pages, LaTeX, revised version with minor corrections to appear in
Phys. Rev.
T-Duality For String in Horava-Lifshitz Gravity
We continue our study of the Lorentz breaking string theories. These theories
are defined as string theory with modified Hamiltonian constraint which breaks
the Lorentz symmetry of target space-time. We analyze properties of this theory
in the target space-time that possesses isometry along one direction. We also
derive the T-duality rules for Lorentz breaking string theories and show that
they are the same as that of Buscher's T-duality for the relativistic strings.Comment: 17 pages, references adde
Five Dimensional Rotating Black Hole in a Uniform Magnetic Field. The Gyromagnetic Ratio
In four dimensional general relativity, the fact that a Killing vector in a
vacuum spacetime serves as a vector potential for a test Maxwell field provides
one with an elegant way of describing the behaviour of electromagnetic fields
near a rotating Kerr black hole immersed in a uniform magnetic field. We use a
similar approach to examine the case of a five dimensional rotating black hole
placed in a uniform magnetic field of configuration with bi-azimuthal symmetry,
that is aligned with the angular momenta of the Myers-Perry spacetime. Assuming
that the black hole may also possess a small electric charge we construct the
5-vector potential of the electromagnetic field in the Myers-Perry metric using
its three commuting Killing vector fields. We show that, like its four
dimensional counterparts, the five dimensional Myers-Perry black hole rotating
in a uniform magnetic field produces an inductive potential difference between
the event horizon and an infinitely distant surface. This potential difference
is determined by a superposition of two independent Coulomb fields consistent
with the two angular momenta of the black hole and two nonvanishing components
of the magnetic field. We also show that a weakly charged rotating black hole
in five dimensions possesses two independent magnetic dipole moments specified
in terms of its electric charge, mass, and angular momentum parameters. We
prove that a five dimensional weakly charged Myers-Perry black hole must have
the value of the gyromagnetic ratio g=3.Comment: 23 pages, REVTEX, v2: Minor changes, v3: Minor change
Mountain Home Air Force Base, Idaho Geothermal Resource Assessment and Future Recommendations
The U.S. Air Force is facing a number of challenges as it moves into the future, one of the biggest being how to provide safe and secure energy to support base operations. A team of scientists and engineers met at Mountain Home Air Force Base in early 2011 near Boise, Idaho, to discuss the possibility of exploring for geothermal resources under the base. The team identified that there was a reasonable potential for geothermal resources based on data from an existing well. In addition, a regional gravity map helped identify several possible locations for drilling a new well. The team identified several possible sources of funding for this wellâthe most logical being to use U.S. Department of Energy funds to drill the upper half of the well and U.S. Air Force funds to drill the bottom half of the well. The well was designed as a slimhole well in accordance with State of Idaho Department of Water Resources rules and regulations. Drilling operations commenced at the Mountain Home site in July of 2011 and were completed in January of 2012. Temperatures increased gradually, especially below a depth of 2000 ft. Temperatures increased more rapidly below a depth of 5500 ft. The bottom of the well is at 5976 ft, where a temperature of about 140°C was recorded. The well flowed artesian from a depth below 5600 ft, until it was plugged off with drilling mud. Core samples were collected from the well and are being analyzed to help understand permeability at depth. Additional tests using a televiewer system will be run to evaluate orientation and directions at fractures, especially in the production zone. A final report on the well exploitation will be forthcoming later this year. The Air Force will use it to evaluate the geothermal resource potential for future private development options at Mountain Home Air Force Base. In conclusion, Recommendation for follow-up efforts include the following
Recommended from our members
Exploration and Resource Assessment at Mountain Home Air Force Base, Idaho Using an Integrated Team Approach
The U.S. Air Force is facing a number of challenges as it moves into the future, one of the biggest being how to provide safe and secure energy to support base operations. A team of scientists and engineers met at Mountain Home Air Force Base near Boise, Idaho, to discuss the possibility of exploring for geothermal resources under the base. The team identified that there was a reasonable potential for geothermal resources based on data from an existing well. In addition, a regional gravity map helped identify several possible locations for drilling a new well. The team identified several possible sources of funding for this wellâthe most logical being to use U.S. Department of Energy funds to drill the upper half of the well and U.S. Air Force funds to drill the bottom half of the well. The well was designed as a slimhole well in accordance with State of Idaho Department of Water Resources rules and regulations. Drilling operations commenced at the Mountain Home site in July of 2011 and were completed in January of 2012. Temperatures increased gradually, especially below a depth of 2000 ft. Temperatures increased more rapidly below a depth of 5500 ft. The bottom of the well is at 5976 ft, where a temperature of about 140°C was recorded. The well flowed artesian from a depth below 5600 ft, until it was plugged off with drilling mud. Core samples were collected from the well and are being analyzed to help understand permeability at depth. Additional tests using a televiewer system will be run to evaluate orientation and directions at fractures, especially in the production zone. A final report on the well exploitation will be forthcoming later this year. The Air Force will use it to evaluate the geothermal resource potential for future private development options at Mountain Home AFB
G-Structures, Fluxes and Calibrations in M-Theory
We study the most general supersymmetric warped M-theory backgrounds with
non-trivial G-flux of the type R^{1,2} x M_8 and AdS_3 x M_8. We give a set of
necessary and sufficient conditions for preservation of supersymmetry which are
phrased in terms of G-structures and their intrinsic torsion. These equations
may be interpreted as calibration conditions for a static ``dyonic'' M-brane,
that is, an M5-brane with self-dual three-form turned on. When the electric
flux is turned off we obtain the supersymmetry conditions and non-linear PDEs
describing M5-branes wrapped on associative and special Lagrangian three-cycles
in manifolds with G_2 and SU(3) structures, respectively. As an illustration of
our formalism, we recover the 1/2-BPS dyonic M-brane, and also construct some
new examples.Comment: 40 pages; v2: one reference added, typos correcte
p-p' Branes in PP-wave Background
We present several supergravity solutions corresponding to both Dp, as well
as Dp-Dp' systems, in NS-NS and R-R PP-wave background originating from AdS_3
times S^3 times R^4. The Dp brane solutions, p=1,..,5 are fully localized,
whereas Dp-Dp' are localized along common transverse directions. We also
discuss the supersymmetry properties of these solutions and the worldsheet
construction for the p-p' system.Comment: 17 pages, v5: supergrav. solns. corrected, v6: more results added:
now includes p-p' branes in both NS-NS and R-R PP-wave background, some
restructuring of the tex
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