Electrical excitation of surface plasmons

We exploit a plasmon mediated two-step momentum downconversion scheme to convert low-energy tunneling electrons into propagating photons. Surface plasmon polaritons (SPPs) propagating along an extended gold nanowire are excited on one end by low-energy electron tunneling and are then converted to free-propagating photons at the other end. The separation of excitation and outcoupling proofs that tunneling electrons excite gap plasmons that subsequently couple to propagating plasmons. Our work shows that electron tunneling provides a non-optical, voltage-controlled and low-energy pathway for launching SPPs in nanostructures, such as plasmonic waveguide

Preliminary design study of nuclear Brayton cycle/Heat Exchanger and Duct Assembly /HXDA/, phase 3 Topical report

Nuclear Brayton cycle heat exchanger and duct assembl

Pressure containment tests in support of the nuclear Brayton cycle heat exchanger and duct assembly /HXDA/, phase 2

Plate-fin heat exchangers for nuclear reactor Brayton cycl

An HTS flux pump operated by directly driving a superconductor into flux flow region in the E- J curve

High $\textit{T}$$_C$ Superconducting (HTS) flux pumps are capable of compensating the persistent current decay in HTS magnets without electrical contact. In this paper, following the work of an LTS self-switching flux pump, we propose a new HTS flux pump by directly driving high $\textit{T}$$_C$ superconductor into flux flow region in the $\textit{E-J}$ curve. The flux pump consists of a transformer which has a superconducting secondary winding shorted by an YBCO coated conductor bridge. A high alternating current with much higher positive peak value than the negative peak value is induced in the secondary winding. The current always drives the bridge superconductor into flux flow region only at around its positive peak value, thus resulting in flux pumping. The proposed flux pump is much simpler than existing HTS flux pumps.Cambridge Trust (Cambridge International Scholarship)This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by IOP Science

Modeling methodology for a HTS flux pump using a 2D H-formulation

Flux pumps are the kind of devices that can magnetize closed superconducting magnets in a gradual manner. High-Tc Superconducting (HTS) flux pumps are particularly promising for high field applications, due to the fact that lossless HTS coils are unavailable. The physics of these devices is also attractive. In this paper, we propose a modeling methodology for a transformer-rectifier HTS flux pump switched by dynamic resistance. A finite element model is built in Comsol and solved by 2D H-formulation. The simulation result is verified by experimental data. The simulation will give a clear picture of how flux pumping occurs in the superconductor. It will show flux motion across a superconductor by shifting the electric central line, which is a unique nature of type-II superconductors. This work may be interesting in the understanding of magnetization of High-Tc Superconductors

Brooksville Shipping Receipt: Ada Francis, 1862

https://digitalmaine.com/blue_hill_documents/1101/thumbnail.jp

Bloodstream form trypanosoma brucei depend upon multiple metacaspases associated with RAB11-positive endosomes

Trypanosoma brucei possesses five metacaspase genes. Of these, MCA2 and MCA3 are expressed only in the mammalian bloodstream form of the parasite, whereas MCA5 is expressed also in the insect procyclic form. Triple RNAi analysis showed MCA2, MCA3 and MCA5 to be essential in the bloodstream form, with parasites accumulating pre-cytokinesis. Nevertheless, triple null mutants (Δmca2/3Δmca5) could be isolated after sequential gene deletion. Thereafter, Δmca2/3Δmca5 mutants were found to grow well both in vitro in culture and in vivo in mice. We hypothesise that metacaspases are essential for bloodstream form parasites, but they have overlapping functions and their progressive loss can be compensated for by activation of alternative biochemical pathways. Analysis of Δmca2/3Δmca5 revealed no greater or lesser susceptibility to stresses reported to initiate programmed cell death, such as treatment with prostaglandin D2. The metacaspases were found to colocalise with RAB11, a marker for recycling endosomes. However, variant surface glycoprotein (VSG) recycling processes and the degradation of internalised anti-VSG antibody were found to occur similarly in wild type, Δmca2/3Δmca5 and triple RNAi induced parasites. Thus, the data provide no support for the direct involvement of T. brucei metacaspases in programmed cell death and suggest that the proteins have a function associated with RAB11 vesicles that is independent of known recycling processes of RAB11-positive endosomes

LDEF data: Comparisons with existing models

The relationship between the observed cratering impact damage on the Long Duration Exposure Facility (LDEF) versus the existing models for both the natural environment of micrometeoroids and the man-made debris was investigated. Experimental data was provided by several LDEF Principal Investigators, Meteoroid and Debris Special Investigation Group (M&D SIG) members, and by the Kennedy Space Center Analysis Team (KSC A-Team) members. These data were collected from various aluminum materials around the LDEF satellite. A PC (personal computer) computer program, SPENV, was written which incorporates the existing models of the Low Earth Orbit (LEO) environment. This program calculates the expected number of impacts per unit area as functions of altitude, orbital inclination, time in orbit, and direction of the spacecraft surface relative to the velocity vector, for both micrometeoroids and man-made debris. Since both particle models are couched in terms of impact fluxes versus impactor particle size, and much of the LDEF data is in the form of crater production rates, scaling laws have been used to relate the two. Also many hydrodynamic impact computer simulations were conducted, using CTH, of various impact events, that identified certain modes of response, including simple metallic target cratering, perforations and delamination effects of coatings