13,608 research outputs found
Super D-branes
We present a manifestly Lorentz invariant, spacetime supersymmetric, and
`-invariant' worldvolume action for all type II Dirichlet p-branes,
, in a general type II supergravity background, including massive
backgrounds in the IIA case. The cases are rederived from D=11. The
case provides a supersymmetrization of the D=10 Born-Infeld action.Comment: 27pp. Typos corrected. To appear in Nucl. Phys.
Solitons on the Supermembrane
Energy bounds are derived for planar and compactified M2-branes in a
hyper-K\"ahler background. These bounds are saturated, respectively, by lump
and Q-kink solitons, which are shown to preserve a half of the worldvolume
supersymmetry. The Q-kinks have a dual IIB interpretation as strings that
migrate between fivebranes.Comment: 18 pp. Latex; v2: minor corrections, version as published in JHE
The unidirectional relationship of nightmares on self-harmful thoughts and behaviors
Understanding the direction of the predictive relationship between nightmares and suicidal behaviors is important to model its underlying mechanisms. We examine the direction of this relationship and the mediating role of negative affect. A fixed interval diary study obtained pre-sleep and post-sleep measures of affect, nightmares, and self-harmful thoughts and behaviors (SHTBs) from 72 university students (88.9% female). The results show predictive utility of nightmares on SHTBs - indicating a fourfold increased risk of SHTBs. Additionally, results support the suggestion of a unidirectional predictive influence (of nightmares on likelihood of SHTBs but not vice versa). Moreover, postsleep negative affect partially mediated the relationship between nightmares and postsleep SHTBs. This empirically validates assumptions of directionality for future models
The Heterotic Dyonic Instanton
The static Yang-Mills-Higgs dyonic instanton is shown to have a
non-vanishing, but anti-self-dual, angular momentum 2-form with skew
eigenvalues equal to the electric charge; for large charge the angular momentum
causes the instanton to expand into a hyper-spherical shell. A class of exact
multi dyonic instantons is then found and then generalized to a new class of
1/4 supersymmetric, non-singular, stationary, exact solutions of the
ten-dimensional supergravity/Yang-Mills theory. These self-gravitating dyonic
instantons yield new heterotic string solitons, to leading order in the inverse
string tension.Comment: 18 pages, LaTeX, no figures. Previous revision was to include exact
multi-solitons. Third version corrects typos and ADM energy formul
Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears
Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears
Evergreen Leasing of Aquaculture Sites
Government policy on siting of aquaculture must balance the objective of providing a long planning horizon for the industry against a broader social interest of adapting lease terms to new environmental information. Evergreen leases are proposed to balance these objectives. Under an evergreen lease, the lease renewal occurs not at the end of the lease, but rather at midterm. For example, a 20-year lease might be renewed at year five or year 10. The mid-term renewal process avoids end-point biases and also creates incentives for the two parties to successfully bargain a renewal. Evergreen leases are an appropriate institution when two parties want a long-term relationship but recognize that terms of the relationship must evolve to reflect new information.aquaculture, evergreen leases, Resource /Energy Economics and Policy, Q22,
Comparisons of modified Vasco X-2 and AISI 9310 gear steels
Endurance tests were conducted with four groups of spur gears manufactured from three heats of consumable electrode vacuum melted (CVM) modified Vasco X-2. Endurance tests were also conducted with gears manufactured from CVM AISI 9310. Bench type rolling element fatigue tests were conducted with both materials. Hardness measurements were made to 811 K. There was no statistically significant life difference between the two materials. Life differences between the different heats of modified Vasco X-2 can be attributed to heat treat variation and resultant hardness. Carburization of gear flanks only can eliminate tooth fracture as a primary failure mode for modified Vasco X-2. However, a tooth surface fatigue spall can act as a nucleus of a tooth fracture failure for the modified Vasco X-2
Axion-Dilaton Domain Walls and Fake Supergravity
Dynamical systems methods are used to investigate domain-wall solutions of a
two-parameter family of models in which gravity is coupled to an axion, and to
a dilaton with an exponential potential of either sign. A complete global
analysis is presented for (i) constant axion and (ii) flat walls, including a
study of bifurcations and a new exact domain-wall solution with non-constant
axion. We reconsider `fake supergravity' issues in light of these results. We
show, by example, how domain walls determine multi-valued superpotentials that
branch at stationary points that are not stationary points of the potential,
and we apply this result to potentials with anti-de Sitter vacua. We also show
by example that `adapted' truncation to a single-scalar model is sometimes
inconsistent, and we propose a `generalized' fake supergravity formalism that
applies in some such cases.Comment: 43pp, 19 figures; minor corrections and extensions; one additional
figur
Effect of five lubricants on life of AISI 9310 spur gears
Spur-gear surface fatigue tests were conducted with five lubricants using a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 spur gears. The lot of gears was divided into five groups, each of which was tested with a different lubricant. The test lubricants are classified as either a synthetic hydrocarbon, mineral oil, or ester-based lubricant. All five lubricants have imilar viscosity and pressure-viscosity coefficients. A pentaerythritol base stock without sufficient antiwear additives produced a surface fatigue life pproximately 22 percent that of the same base stock with chlorine and phosphorus type additives. The presence of sulfur type antiwear additives in the lubricant did not appear to affect the surface fatigue life of the gears tested. No statistical difference in the 10-percent surface fatigue life was produced with four of the five lubricants
Effects of antiwear and extreme pressure additives in a synthetic paraffinic lubricant on ball spinning torque
Effects of antiwear and extreme-pressure additives in synthetic paraffinic oil on ball spinning torqu
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