Dependence of Maximum Trappable Field on Superconducting Nb3Sn Cylinder Wall Thickness

Uniform dipole magnetic fields from 1.9 to 22.4 kOe were permanently trapped, with high fidelity to the original field, transversely to the axes of hollow Nb3Sn superconducting cylinders. These cylinders were constructed by helically wrapping multiple layers of superconducting ribbon around a mandrel. This is the highest field yet trapped, the first time trapping has been reported in such helically wound taped cylinders, and the first time the maximum trappable field has been experimentally determined as a function of cylinder wall thickness.Comment: 8 pages, 4 figures, 1 table. PACS numbers: 74.60.Ge, 74.70.Ps, 41.10.Fs, 85.25.+

Black Hole Radiation and Volume Statistical Entropy

The simplest possible equation for Hawking radiation, and other black hole radiated power is derived in terms of black hole density. Black hole density also leads to the simplest possible model of a gas of elementary constituents confined inside a gravitational bottle of Schwarzchild radius at tremendous pressure, which yields identically the same functional dependence as the traditional black hole entropy. Variations of Sbh can be obtained which depend on the occupancy of phase space cells. A relation is derived between the constituent momenta and the black hole radius which is similar to the Compton wavelength relation.Comment: 11 pages, no figures. Key Words: Black Hole Entropy, Hawking Radiation, Black Hole density. This is a better pdf versio

Phenomenological theory of cuprate superconductivity

Reasonably good agreement with the superconducting transitiontemperatures of the cuprate high‐T c superconductors can be obtained on the basis of an approximate phenomenological theory. In this theory, two criteria are used to calculate the superconducting transitiontemperature. One is that the quantum wavelength is of the order of the electron‐pair spacing. The other is that a fraction of the normal carriers exist as Cooper pairs at T c . The resulting simple equation for T c contains only two parameters: the normal carrier density and effective mass. We calculate specific transition temperatures for 12 cuprate superconductors

Anti-sense And Common-sense: Regulation of Food From Genetically Engineered Plants

Genetic engineering technology has recently generated techniques for making specific and precise alterations to the genetic composition of crops grown as food for humans and animals. These advances should facilitate the development of crops with enhanced resistance to diseases, pests and bad weather, improved tolerance of environmentally safer herbicides, and greater nutritional value. However, the very power of these techniques has raised fears of potential ecological catastrophe, as well as religious and aesthetic questions that arise from the prospect of vegetables containing genes ultimately derived from fish and animals. This essay briefly reviews the nature of the technology and its potential benefits and risks. It then discusses the regulatory framework with particular emphasis on the regulatory strategy adopted by FDA. Finally, it suggests that FDA's stance, while legally and scientifically defensible, is strategically misconceived in that stricter regulation would promote public acceptance of this technology

Frictional Behavior of Input Sediments to the Hikurangi Trench, New Zealand

AbstractThe Hikurangi subduction zone hosts shallow slow‐slip events, possibly extending to the seafloor. The mechanisms allowing for this behavior are poorly understood but are likely a function of the frictional properties of the downgoing seafloor sediments. We conducted friction experiments at a large range of effective stresses, temperatures, and velocities on incoming sediment to the Hikurangi subduction zone to explore the possible connection of frictional properties to slow‐slip events. These experiments were conducted on multiple apparatuses, allowing us to access a wider range of deformation conditions than is available on any one machine. We find that the material frictionally weakens and becomes less velocity strengthening with increasing effective stress, whereas temperature has only a small effect on both friction and frictional stability. When driven at the plate convergence rate, the sediment exhibits velocity‐weakening behavior. These results imply that the frictional properties of the sediment package subducting at Hikurangi could promote slow‐slip events at the pressures, temperatures, and strain rates expected along the plate boundary thrust up to 10‐km depth without requiring elevated pore fluid pressures. The transition to velocity‐strengthening behavior at faster slip rates could provide a mechanism for limiting unstable slip to slow‐sliding velocities, rather than accommodating deformation through ordinary earthquakes

Earthquake slip surfaces identified by biomarker thermal maturity within the 2011 Tohoku-Oki earthquake fault zone.

Extreme slip at shallow depths on subduction zone faults is a primary contributor to tsunami generation by earthquakes. Improving earthquake and tsunami risk assessment requires understanding the material and structural conditions that favor earthquake propagation to the trench. We use new biomarker thermal maturity indicators to identify seismic faults in drill core recovered from the Japan Trench subduction zone, which hosted 50 m of shallow slip during the Mw9.1 2011 Tohoku-Oki earthquake. Our results show that multiple faults have hosted earthquakes with displacement ≥ 10 m, and each could have hosted many great earthquakes, illustrating an extensive history of great earthquake seismicity that caused large shallow slip. We find that lithologic contrasts in frictional properties do not necessarily determine the likelihood of large shallow slip or seismic hazard

Discovery of near-Earth asteroids by CCD scanning

The found near-Earth asteroid are different objects with peculiar orbits. With the new technique of CCD scanning we entered the domain of the smallest, the fastest, and the closest near-Earth asteroids. The results are presented