35,942 research outputs found
A hermeneutic inquiry into user-created personas in different Namibian locales
Persona is a tool broadly used in technology design to support communicational interactions between designers and users. Different Persona types and methods have evolved mostly in the Global North, and been partially deployed in the Global South every so often in its original User-Centred Design methodology. We postulate persona conceptualizations are expected to differ across cultures. We demonstrate this with an exploratory-case study on user-created persona co-designed with four Namibian ethnic groups: ovaHerero, Ovambo, ovaHimba and Khoisan. We follow a hermeneutic inquiry approach to discern cultural nuances from diverse human conducts. Findings reveal diverse self-representations whereby for each ethnic group results emerge in unalike fashions, viewpoints, recounts and storylines. This paper ultimately argues User-Created Persona as a potentially valid approach for pursuing cross-cultural depictions of personas that communicate cultural features and user experiences paramount to designing acceptable and gratifying technologies in dissimilar locales
A study of ingestion and dispersion of engine exhaust products in trailing vortex systems
Analysis has been made of the ingestion and dispersion of engine exhaust products into the trailing vortex system of supersonic aircraft flying in the stratosphere. The rate of mixing between the supersonic jet and the co-flowing supersonic stream was found to be an order of magnitude less than would be expected on the basis of subsonic eddy-viscosity results. The length of the potential core was 66 nozzle exit radii so that the exhaust gases remain at elevated temperatures and concentrations over much longer distances than previsously estimated. Ingestion started at the end of the potential core and all hot gas from the engine was ingested into the trailing vortex within two core lengths. Comparison between the buoyancy calculations for the supersonic case with nondimensionalized subsonic aircraft contrail data on wake spreading showed good agreement. Velocity and temperature profiles have been specified at various stages of the wake, and the analysis in this report can be used to predict variations of concentrations of species such as nitrogen oxides under conditions of chemical reaction
Factorization and entanglement in general XYZ spin arrays in non-uniform transverse fields
We determine the conditions for the existence of a pair of degenerate parity
breaking separable eigenstates in general arrays of arbitrary spins connected
through couplings of arbitrary range and placed in a transverse field,
not necessarily uniform. Sufficient conditions under which they are ground
states are also provided. It is then shown that in finite chains, the
associated definite parity states, which represent the actual ground state in
the immediate vicinity of separability, can exhibit entanglement between any
two spins regardless of the coupling range or separation, with the reduced
state of any two subsystems equivalent to that of pair of qubits in an
entangled mixed state. The corresponding concurrences and negativities are
exactly determined. The same properties persist in the mixture of both definite
parity states. These effects become specially relevant in systems close to the
limit. The possibility of field induced alternating separable solutions
with controllable entanglement side limits is also discussed. Illustrative
numerical results for the negativity between the first and the
spin in an open spin chain for different values of and are as well
provided.Comment: 6 pages, figures adde
Optical observations of the AMPTE artificial comet and magnetotail barium releases
The first AMPTE artificial comet was observed with a low light level television camera operated aboard the NASA CV990 flying out of Moffett Field, California. The comet head, neutral cloud, and comet tail were all observed for four minutes with an unifiltered camera. Brief observations at T + 4 minutes through a 4554A Ba(+) filter confirmed the identification of the structures. The ion cloud expanded along with the neutral cloud at a rate of 2.3 km/sec (diameter) until it reached a final diameter of approx. 170 km at approx. T + 90 s. It also drifted with the neutral cloud until approx. 165 s. By T + 190 s it had reached a steady state velocity of 5.4 km/sec southward. A barium release in the magnetotail was observed from the CV990 in California, Eagle, Alaska, and Fairbanks, Alaska. Over a twenty-five minute period, the center of the barium streak drifted southward (approx. 500 m/sec), upward (24 km/sec) and eastward (approx 1 km/sec) in a nonrotating reference frame. An all-sky TV at Eagle showed a single auroral arc in the far North during this period
Mode-Field Radius of Photonic Crystal Fibers Expressed by the V-parameter
We numerically calculate the equivalent mode-field radius of the fundamental
mode in a photonic crystal fiber (PCF) and show that this is a function of the
V-parameter only and not the relative hole size. This dependency is similar to
what is found for graded-index standard fibers and we furthermore show that the
relation for the PCF can be excellently approximated with the same general
mathematical expression. This is to our knowledge the first semi-analytical
description of the mode-field radius of a PCF.Comment: Accepted for Opt. Let
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