Development of a task analysis tool to facilitate user interface design

A good user interface is one that facilitates the user in carrying out his task. Such interfaces are difficult and costly to produce. The most important aspect in producing a good interface is the ability to communicate to the software designers what the user's task is. The Task Analysis Tool is a system for cooperative task analysis and specification of the user interface requirements. This tool is intended to serve as a guide to development of initial prototypes for user feedback

Harmonic oscillator in a background magnetic field in noncommutative quantum phase-space

We solve explicitly the two-dimensional harmonic oscillator and the harmonic oscillator in a background magnetic field in noncommutative phase-space without making use of any type of representation. A key observation that we make is that for a specific choice of the noncommutative parameters, the time reversal symmetry of the systems get restored since the energy spectrum becomes degenerate. This is in contrast to the noncommutative configuration space where the time reversal symmetry of the harmonic oscillator is always broken.Comment: 7 pages Late

Non-commutative Quantum Mechanics in Three Dimensions and Rotational Symmetry

We generalize the formulation of non-commutative quantum mechanics to three dimensional non-commutative space. Particular attention is paid to the identification of the quantum Hilbert space in which the physical states of the system are to be represented, the construction of the representation of the rotation group on this space, the deformation of the Leibnitz rule accompanying this representation and the implied necessity of deforming the co-product to restore the rotation symmetry automorphism. This also implies the breaking of rotational invariance on the level of the Schroedinger action and equation as well as the Hamiltonian, even for rotational invariant potentials. For rotational invariant potentials the symmetry breaking results purely from the deformation in the sense that the commutator of the Hamiltonian and angular momentum is proportional to the deformation.Comment: 21 page

SPS pilot signal design and power transponder analysis, volume 2, phase 3

The problem of pilot signal parameter optimization and the related problem of power transponder performance analysis for the Solar Power Satellite reference phase control system are addressed. Signal and interference models were established to enable specifications of the front end filters including both the notch filter and the antenna frequency response. A simulation program package was developed to be included in SOLARSIM to perform tradeoffs of system parameters based on minimizing the phase error for the pilot phase extraction. An analytical model that characterizes the overall power transponder operation was developed. From this model, the effects of different phase noise disturbance sources that contribute to phase variations at the output of the power transponders were studied and quantified. Results indicate that it is feasible to hold the antenna array phase error to less than one degree per power module for the type of disturbances modeled

Twist Deformation of Rotationally Invariant Quantum Mechanics

Non-commutative Quantum Mechanics in 3D is investigated in the framework of the abelian Drinfeld twist which deforms a given Hopf algebra while preserving its Hopf algebra structure. Composite operators (of coordinates and momenta) entering the Hamiltonian have to be reinterpreted as primitive elements of a dynamical Lie algebra which could be either finite (for the harmonic oscillator) or infinite (in the general case). The deformed brackets of the deformed angular momenta close the so(3) algebra. On the other hand, undeformed rotationally invariant operators can become, under deformation, anomalous (the anomaly vanishes when the deformation parameter goes to zero). The deformed operators, Taylor-expanded in the deformation parameter, can be selected to minimize the anomaly. We present the deformations (and their anomalies) of undeformed rotationally-invariant operators corresponding to the harmonic oscillator (quadratic potential), the anharmonic oscillator (quartic potential) and the Coulomb potential.Comment: 20 page

Formulation, Interpretation and Application of non-Commutative Quantum Mechanics

In analogy with conventional quantum mechanics, non-commutative quantum mechanics is formulated as a quantum system on the Hilbert space of Hilbert-Schmidt operators acting on non-commutative configuration space. It is argued that the standard quantum mechanical interpretation based on Positive Operator Valued Measures, provides a sufficient framework for the consistent interpretation of this quantum system. The implications of this formalism for rotational and time reversal symmetry are discussed. The formalism is applied to the free particle and harmonic oscillator in two dimensions and the physical signatures of non commutativity are identified.Comment: 11 page

A Helix Propensity Scale Based on Experimental Studies of Peptides and Proteins

AbstractThe average globular protein contains 30% α-helix, the most common type of secondary structure. Some amino acids occur more frequently in α-helices than others; this tendency is known as helix propensity. Here we derive a helix propensity scale for solvent-exposed residues in the middle positions of α-helices. The scale is based on measurements of helix propensity in 11 systems, including both proteins and peptides. Alanine has the highest helix propensity, and, excluding proline, glycine has the lowest, ∼1kcal/mol less favorable than alanine. Based on our analysis, the helix propensities of the amino acids are as follows (kcal/mol): Ala=0, Leu=0.21, Arg=0.21, Met=0.24, Lys=0.26, Gln=0.39, Glu=0.40, Ile=0.41, Trp=0.49, Ser=0.50, Tyr=0.53, Phe=0.54, Val=0.61, His=0.61, Asn=0.65, Thr=0.66, Cys=0.68, Asp=0.69, and Gly=1

Logistics-related customer complaints in the South African retail industry

Abstract: Intense competition in the South African fast-moving customer goods (FMCG) retailing industry often results in price wars that encourage customer switching behaviour. Time and place utility provided by distribution, equates to customer service and forms part of the competitive strategy of retailers. Solving last-mile logistical problems in-store could be a valuable strategy in differentiation and building customer loyalty. The purpose of this study was to explore the nature of logistics-related customer complaints concerning South African mass grocery retailers (MGR) as lodged on customer complaints website Hellopeter.com, pertaining to the three largest MGR groups for the period of one year ending August 2016..

Noncommutative quantum mechanics -- a perspective on structure and spatial extent

We explore the notion of spatial extent and structure, already alluded to in earlier literature, within the formulation of quantum mechanics on the noncommutative plane. Introducing the notion of average position and its measurement, we find two equivalent pictures: a constrained local description in position containing additional degrees of freedom, and an unconstrained nonlocal description in terms of the position without any other degrees of freedom. Both these descriptions have a corresponding classical theory which shows that the concept of extended, structured objects emerges quite naturally and unavoidably there. It is explicitly demonstrated that the conserved energy and angular momentum contain corrections to those of a point particle. We argue that these notions also extend naturally to the quantum level. The local description is found to be the most convenient as it manifestly displays additional information about structure of quantum states that is more subtly encoded in the nonlocal, unconstrained description. Subsequently we use this picture to discuss the free particle and harmonic oscillator as examples.Comment: 25 pages, no figure

Evidence of extended cold molecular gas and dust haloes around z ∼ 2.3 extremely red quasars with ALMA

Large-scale outflows are believed to be an important mechanism in the evolution of galaxies. We can determine the impact of these outflows by studying either current galaxy outflows and their effect in the galaxy or by studying the effect of past outflows on the gas surrounding the galaxy. In this work, we examine the CO(7-6), [C I] (3P1→ 3P0), H2O 211-202, and dust continuum emission of 15 extremely red quasars at z ∼2.3 using ALMA. By investigating the radial surface brightness profiles of both the individual sources and the stacked emission, we detect extended cold gas and dust emission on scales of ∼14 kpc in CO(7-6), [C I](2-1), and dust continuum. This is the first time that the presence of a large amount of molecular gas was detected on large, circumgalactic medium scales around quasar host galaxies using [C i] extended emission. We estimate the dust and molecular gas mass of these haloes to be 107.6 and 1010.6 M⊙, indicating significant dust and molecular gas reservoirs around these extreme quasars. By estimating the time-scale at which this gas can reach these distances by molecular gas outflows (7-32 Myr), we conclude that these haloes are a relic of past AGN or starburst activity, rather than an effect of the current episode of extreme quasar activity