Microscopic laser-driven high-energy colliders

The concept of a laser-guided $e^+e^-$ collider in the high-energy regime is presented and its feasibility discussed. Ultra-intense laser pulses and strong static magnetic fields are employed to unite in one stage the electron and positron acceleration and their head-on-head collision. We show that the resulting coherent collisions in the GeV regime yield an enormous enhancement of the luminosity with regard to conventional incoherent colliders

Aerodynamic Interference on Finned Slender Body

Aerodynamic interference can occur between high-speed slender bodies when in close proximity. A complex flowfield develops where shock and expansion waves from a generator body impinge upon the adjacent receiver body and modify its aerodynamic characteristics in comparison to the isolated case. The aim of this research is to quantify and understand the multibody interference effects that arise between a finned slender body and a second disturbance generator body. A parametric wind tunnel study was performed in which the effects of the receiver incidence and axial stagger were considered. Computational fluid dynamic simulations showed good agreement with the measurements, and these were used in the interpretation of the experimental results. The overall interference loads for a given multibody configuration were found to be a complex function of the pressure footprints from the compression and expansion waves emanating from the generator body as well as the flow pitch induced by the generator shockwave. These induced interference loads change sign as the shock impingement location moves aft over the receiver and in some cases cause the receiver body to become statically unstable. Overall, the observed interference effects can modify the subsequent body trajectories and may increase the likelihood of a collision

A simple interpretation of the Fe2(-) photoelectron spectrum

The photoelectron spectrum of Fe2(-) can be simply interpreted in terms of electron detachment from the mildly bonding 4s sigma sup * sub u orbital of a (4s sigma sub s)(sup 2) (4s sigma sup * sub u)(sup 2) (3d)(sup 13) anion. This interpretation implies a (4s sigma sub g)(sup 2) (4s sigma sup * sub u)(sup1) (3d)(sup13) configuration for the ground state of Fe2, correlating with one ground state (4s2 3d6) and one excited state (4s1 3d7) Fe atom. A comparison of the bond length and vibrational frequency of Fe2 to values for transition metal dimers containing single 4s-4s bonds is suggestive of 3d-3d bonding in this molecule. The results of preliminary full-valence configuration interaction calculations provide stron support for the proposed Fe2 and Fe2(-) configurations

Satellite power system: Concept development and evaluation program. Volume 3: Power transmission and reception. Technical summary and assessment

Efforts in the DOE/NASA concept development and evaluation program are discussed for the solar power satellite power transmission and reception system. A technical summary is provided together with a summary of system assessment activities. System options and system definition drivers are described. Major system assessment activities were in support of the reference system definition, solid state system studies, critical technology supporting investigations, and various system and subsystem tradeoffs. These activities are described together with reference system updates and alternative concepts for each of the subsystem areas. Conclusions reached as a result of the numerous analytical and experimental evaluations are presented. Remaining issues for a possible follow-on program are identified

The Determination of Sex

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Sulfate attack and embedded steel corrosion resistances of volcanic-aggregate concrete with fly ash and silica fume

Construction materials are increasingly on high demand in the developing world. The construction industry has a challenge of discovering, new  alternative construction materials to conventional materials which are locally available materials in environmentally friendly manner. The  experimental tests are conducted on volcanic concrete system to analyze its properties especially corrosion resistance potential for its applicability in construction. The major aim is to investigate its suitability and corrosion resistance potential especially when used in construction of structures with embedded steel. The test results of the material show that volcanic concrete system with 30% fly ash and 10% silica fume cementing materials is an alternative green construction material. Permeability properties are reduced by 8% and 24% with 30% fly ash and 10% silica fume respectively. Tests also indicate that Compressive strength, Corrosion potential and polarization resistance in volcanic concrete system with supplementing  cement materials has more potential to resist sulfate attack when compared with conventional volcanic concrete systems. The supplementary cementing materials (SCM) reduce the pore system and hence decrease the ingress of corrosive ions an  water in concrete. Corrosive ions, moisture and air would initiate corrosion to the embedded steel in concrete leading to reduced service life such structures. Key word: Supplementary Cementing Materials, Sulfate attack, volcanic concrete system, Granite powder, river sand, Corrosion of embedded stee

Functional Layer-By-Layer Design of Xerogel-Based 1st Generation Amperometric Glucose Biosensors

Xerogel-based first-generation amperometric glucose biosensors, constructed through specific layer-by-layer assembly of films featuring glucose oxidase doped xerogel, a diffusion-limiting xerogel layer, and capped with both electropolymerized polyphenol and blended polyurethane semipermeable membranes, are presented. The specific combination of xerogels formed from specific silane precursors, including propyl-trimethoxysilane, isobutyl-trimethoxysilane, octyl-trimethoxysilane, and hydroxymethyl-triethoxysilane, exhibit impressive dynamic and linear ranges of detection (e.g., ≥24–28 mM glucose) and low response times, as well as significant discrimination against common interferent species such as acetaminophen, ascorbic acid, sodium nitrite, oxalic acid, and uric acid as determined by selectivity coefficients. Additionally, systematic electrochemical and contact angle studies of different xerogel silane precursors, varying in structure, chain length, and/or functional group, reveal that sensor performance is more dependent on the tunable porosity/permeability of the layered interfaces rather than the hydrophobic character or functional groups within the films. While the sensing performance largely exceeds that of existing electrochemical glucose sensing schemes in the literature, the presented layered approach establishes the specific functionality of each layer working in concert with each other and suggests that the strategy may be readily adaptable to other clinically relevant targets and is amenable to miniaturization for eventual in situ or in vivo sensing

Excitation of Small Quantum Systems by High-Frequency Fields

The excitation by a high frequency field of multi--level quantum systems with a slowly varying density of states is investigated. A general approach to study such systems is presented. The Floquet eigenstates are characterized on several energy scales. On a small scale, sharp universal quasi--resonances are found, whose shape is independent of the field parameters and the details of the system. On a larger scale an effective tight--binding equation is constructed for the amplitudes of these quasi--resonances. This equation is non--universal; two classes of examples are discussed in detail.Comment: 4 pages, revtex, no figure