High-efficiency Dc to Dc Converter-regulators

High efficiency dc to dc converter regulators for spacecraft power suppl

Transmission Lines and Meta-Materials based on Quantum Hall Plasmonics

The characteristic impedance of a microwave transmission line is typically constrained to a value $Z_0$ = 50 $\Omega$, in-part because of the low impedance of free space and the limited range of permittivity and permeability realizable with conventional materials. Here we suggest the possibility of constructing high-impedance transmission lines by exploiting the plasmonic response of edge states associated with the quantum Hall effect in gated devices. We analyze various implementations of quantum Hall transmission lines based on distributed networks and lumped-element circuits, including a detailed account of parasitic capacitance and Coulomb drag effects, which can modify device performance. We additionally conceive of a meta-material structure comprising arrays of quantum Hall droplets and analyze its unusual properties. The realization of such structures holds promise for efficiently wiring-up quantum circuits on chip, as well as engineering strong coupling between semiconductor qubits and microwave photons

X-band scattering measurements of earth surfaces from an aircraft

Airborne equipment for measuring X band scattering of earth surface

Flight tests of a radar scattering-coefficient measuring instrument. Part 1 - Summary

Flight tests of radar scattering coefficient measuring instrumen

The Challenges to Mission and Ministry in the COVID-19 Moment in Jesuit Higher Education

In this Reflection, Father Bosco examines the adaptations and adjustments made at Georgetown University as students, faculty and staff managed with the impact of the coronavirus

Patrons d'utilització dels recursos durant la temporada de creixement de les cries per gavines i xatracs reproductors a una llacuna mediterrània

Patterns of resource utilization, habitat use for feeding and foraging techniques within a gull and tern breeding community were evaluated in a coastal lagoon of the western Mediterranean (l’Albufera de València, E Spain) during the chick rearing season. Five habitat types were identified as foraging habitats at the study site; all were exploited to a variable extent indicating different access to food resources and foraging divergence among the species. Our analyses suggested differences in resource exploitation and structured the species into three groups of (1) species foraging the rice paddies and the lagoon (Mediterranean gull Larus melanocephalus, Audouin's gull L. audouinii, yellow-legged gull L. michahellis, gull-billed tern Gelochelidon nilotica and whiskered tern Chlidonias hybrida); (2) species combining the rice paddies and the brackish marshes (black-headed gull Chroicocephalus ridibundus, slender-billed gull C. genei); and (3) species foraging the open waters, particularly at sea (sandwich tern S. sandvicensis, common tern S. hirundo, little tern Sternula albifrons). Our results showed that the species with larger local breeding population (i.e., common tern, black-headed gull, sandwich tern, Audouin's gull, and gull-billed tern) were successfully exploiting the most advantageous resources (i.e., rice field marshes and marine waters) in terms of prey abundance and timing with brood rearing. The extensive transformation of natural wetland habitats at the study site and the lack of alternative, productive foraging habitats during the breeding season may endanger the thriving gull and tern colonies that came along with recent conservation efforts.S’avaluen els patrons d'utilització dels recursos, l’ús de l'hàbitat per a l’alimentació i les tècniques d’alimentació dins d'una comunitat de gavines i xatracs reproductors a una llacuna litoral de la Mediterrània Occidental (l'Albufera de València, Est d’Espanya) durant l’estació de creixement de les seves cries. Cinc tipus d'hàbitat van ser identificats com a hàbitats d’alimentació al lloc d'estudi; tots van ser explotats en un grau variable la qual cosa indica diferent accés als recursos alimentaris i divergències d'alimentació entre les espècies. Les nostres anàlisis van suggerir diferències d’explotació dels recursos i van assignar les espècies en tres grups: (1) alimentant-se als camps d'arròs i la llacuna (gavina capnegra Larus melanocephalus, gavina corsa L. audouinii, gavià argentat mediterrani L. michahellis, curroc Gelochelidon nilotica i fumarell de galta blanca Chlidonias hybrida); (2) espècies que combinen els camps d'arròs i els estanys salobrencs (gavina vulgar Chroicocephalus ridibundus, gavina capblanca C. genei); i (3) espècies alimentant-se a aigües obertes, particularment a la mar (xatrac becllarg S. sandvicensis, xatrac comú S. hirundo, mongeta Sternula albifrons). Els nostres resultats van mostrar que les espècies amb les poblacions reproductores locals més grans (i.e., xatrac comú, gavina vulgar, xatrac becllarg, gavina corsa, i curroc) explotaven amb èxit els recursos més avantatjosos (i.e., arrossars i aigües marines) en termes d'abundància de preses i de sincronització amb el creixement de les cries. L'extensa transformació dels hàbitats palustres naturals al lloc d'estudi i la manca d’hàbitats d’alimentació alternatius i productius durant l'estació reproductora, poden posar en perill les colònies de gavines i xatracts que es van establir tot seguint esforços recents de conservació

Quantum erasure in the presence of a thermal bath: the effects of system-environment microscopic correlations

We investigate the role of the environment in a quantum erasure setup in the cavity quantum electrodynamics domain. Two slightly different schemes are analyzed. We show that the effects of the environment vary when a scheme is exchanged for another. This can be used to estimate the macroscopic parameters related to the system-environment microscopic correlations.Comment: 10 pages, 2 figure

Effects of Hypohydration on Work Performance and Tolerance to plus Gz Acceleration in Man

Hypohydration effects on work performance and tolerance to acceleration stress in ma

Interfacial Intermetallic Growth and Strength of Composite Lead-Free Solder Alloy Through Isothermal Aging

The effects of particle reinforcement of Sn-4.0wt.%Ag-0.5wt.%Cu (SAC405) lead-free solder on interfacial intermetallic layer growth and strength of the ensuing joints through short-term isothermal aging (150°C) were studied. Composite solders were prepared by either incorporating 2wt.% Cu (3μm to 20μm) or Cu2O (∼150nm) particles into SAC405 paste. Aggressive flux had the effect of reducing the Cu2O nanoparticles into metallic Cu which subsequently reacted with the solder alloy to form the Cu6Sn5 intermetallic. While all solders had similar interfacial intermetallic growth upon reflow, both of the composite solders' growth rates slowed through aging to reach a common growth rate exponent of approximately 0.38, considerably lower than that of the nonreinforced solder (n=0.58). The nanoscale reinforced solder additionally exhibited the highest tensile strength in both the initial and aged conditions, behavior also attributed to its quick conversion to a stable microstructur