The Analyst's View of Complex Systems Projects

The general systems model based on inputs, processes, and outputs is useful for defining and documenting a development project, but it may not be the mental model that analysts and programmers actually use to differentiate system elements. An exploratory study using multidimensional scaling suggests that employing other dimensions during requirements analysis, functional decomposition, and even final documentation may help manage some of the complexity of today's software.     

Decomposition of Ni2SiO4 in an Oxygen Potential Gradient

Polycrystalline Ni₂SiO₄ was exposed to a gradient in oxygen potential at 1336°C to cause kinetic decomposition into its component oxides, NiO and SO2. At the higher-oxygen-potential side NiO formed, and at the lower-oxygen-potential side SiO₂ formed. This spatial distribution of SiO₂ and NiO is consistent with diffusion data for silicate olivines which indicate that Ni diffuses much faster than either Si or O.     

Depression and preference for self-focusing stimuli after success and failure.

Hypothesized that depressives, unlike nondepressives, do not find self-focus more aversive after failure than after success, and thus either (a) show no differential preference for self-focusing stimuli after success vs after failure (weak hypothesis) or (b) prefer self-focusing stimuli after failure over self-focusing stimuli after success (strong hypothesis). 36 female and 20 male undergraduate students, selected on the basis of their scores on the Beck Depression Inventory, were randomly assigned to outcome conditions in a 2?×?2 (nondepressed vs depressed?×?success vs failure) factorial design. Ss succeeded or failed on a supposed test of verbal intelligence and then worked on 2 sets of puzzles, 1 in the presence and 1 in the absence of a self-focusing stimulus (mirror). Results indicate that, whereas nondepressed Ss liked the mirror-associated puzzle more after success than after failure, depressed Ss did not; depressed Ss tended to like the mirror-associated puzzle more after failure than after success. Nondepressed Ss also exhibited a self-serving pattern of attributions, viewing the test as less valid and luck as more responsible for their performance after failure than after success; depressed Ss showed no such differences. Consistent with their failure to use defensive strategies, depressed Ss showed a decrease in self-esteem after failure; nondepressed Ss showed no such change. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neon Ion Beam Lithography (NIBL)

Existing techniques for electron- and ion-beam lithography, routinely employed for nanoscale device fabrication and mask/mold prototyping, do not simultaneously achieve efficient (low fluence) exposure and high resolution. We report lithography using neon ions with fluence <1 ion/nm(2), ～1000× more efficient than using 30 keV electrons, and resolution down to 7 nm half-pitch. This combination of resolution and exposure efficiency is expected to impact a wide array of fields that are dependent on beam-based lithography.     

Measurement of the repeatability of the prompt flashlamp-induced wavefront aberration on beamlines at the National Ignition Facility

We have undertaken a measurement campaign to determine the repeatability of the prompt flashlamp-induced wavefront aberration on beamlines at the National Ignition Facility (NIF) and determine the extent to which shot-to-shot variations in this aberration may degrade the performance of a proposed adaptive optics system for the short-pulse Advanced Radiographic Capability beamline on NIF. In this paper we will describe the unique NIF configuration that was required to make this measurement, present the results of the experiment, and discuss the implications of these results for the adaptive optics system design.     

The effect of dopants on the morphology, microstructure and electrical properties of transparent zinc oxide films prepared by the sol-gel method

The influence of doping on the morphology, physical and electrical properties of zinc oxide produced by the sol-gel method was examined. Undoped zinc oxide was observed to form relatively porous films. Addition of an Al dopant influenced the sheet resistance, but did not result in a change in morphology, examined by atomic force microscopy when compared to undoped films. In the case of electrical measurements, undoped ZnO films were extremely resistive. A minimum dopant concentration of 2 at.%. Al was required to produce materials which were more conductive, as observed by sheet resistance measurements, which were shown to vary with annealing temperature. The versatile nature of sol-gel processing was demonstrated by selective ink-jet deposition of sol-gel droplets which were annealed to form oxide materials.     

Plasticity in small-sized metallic systems: Intrinsic versus extrinsic size effect

A material strength depends on its microstructure, which in turn, is controlled by an engineering process. Strengthening mechanisms like work hardening, precipitate, and grain boundary strengthening can alter the strength of a material in a predictive, quantitative manner and are readily linked to the deformation mechanism. This quantification strongly depends on the characteristic length scale of a particular microstructure, thereby dictating bulk material’s strength as a function of, for example, grain or precipitate size, twin boundary spacing, or dislocation density. This microstructural, or intrinsic, size governs the mechanical properties and post-elastic material deformation at all sample dimensions, as the classical definition of “ultimate tensile strength” deems it to be “an intensive property, therefore its value does not depend on the size of the test specimen.” Yet in the last 5 years, the vast majority of uniaxial deformation experiments and computations on small-scale metallic structures unambiguously demonstrated that at the micron and sub-micron scales, this definition no longer holds true. In fact, it has been shown that in single crystals the ultimate tensile strength and the yield strength scale with external sample size in a power law fashion, sometimes attaining a significant fraction of material’s theoretical strength, and exhibiting the now-commonly-known phenomenon “smaller is stronger.” Understanding of this “extrinsic size effect” at small scales is not yet mature and is currently a topic of rigorous investigations. As both the intrinsic (i.e. microstructural) and extrinsic (i.e. sample size) dimensions play a non-trivial role in the mechanical properties and material deformation mechanisms, it is critical to develop an understanding of their interplay and mutual effects on the mechanical properties and material deformation, especially in small-scale structures. This review focuses on providing an overview of metal-based material classes whose properties as a function of external size have been investigated and provides a critical discussion on the combined effects of intrinsic and extrinsic sizes on the material deformation behavior.     

Anthropocene streams and base-level controls from historic dams in the unglaciated mid-Atlantic region, USA

Recently, widespread valley-bottom damming for water power was identified as a primary control on valley sedimentation in the mid-Atlantic US during the late seventeenth to early twentieth century. The timing of damming coincided with that of accelerated upland erosion during post-European settlement land-use change. In this paper, we examine the impact of local drops in base level on incision into historic reservoir sediment as thousands of ageing dams breach. Analysis of lidar and field data indicates that historic milldam building led to local base-level rises of 2-5 m (typical milldam height) and reduced valley slopes by half. Subsequent base-level fall with dam breaching led to an approximate doubling in slope, a significant base-level forcing. Case studies in forested, rural as well as agricultural and urban areas demonstrate that a breached dam can lead to stream incision, bank erosion and increased loads of suspended sediment, even with no change in land use. After dam breaching, key predictors of stream bank erosion include number of years since dam breach, proximity to a dam and dam height. One implication of this work is that conceptual models linking channel condition and sediment yield exclusively with modern upland land use are incomplete for valleys impacted by milldams. With no equivalent in the Holocene or late Pleistocene sedimentary record, modern incised stream-channel forms in the mid-Atlantic region represent a transient response to both base-level forcing and major changes in land use beginning centuries ago. Similar channel forms might also exist in other locales where historic milling was prevalent.     

Disentangling the prospective relations between maladaptive cognitions and depressive symptoms.

In a four-wave, cohort-longitudinal design with a community sample of 515 children and adolescents (grades 2 through 9), this study examined the longitudinal structure of and prospective interrelations between maladaptive cognitions and depressive symptoms. Multigroup structural equation modeling generated four major findings. First, the longitudinal structures of maladaptive cognitions and depressive symptoms consist of a single time-invariant factor and a series of time-varying factors. Second, evidence supported a model in which depressive symptoms predicted negative cognitions but not the reverse. Third, the time-invariant components of cognition and depression were highly correlated. Fourth, the strength of the depression-to-cognition relation increased with age. Implications regarding the mechanisms underlying clinical interventions with depressed children are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Merging expert and empirical data for rare event frequency estimation: Pool homogenisation for empirical Bayes models

Empirical Bayes provides one approach to estimating the frequency of rare events as a weighted average of the frequencies of an event and a pool of events. The pool will draw upon, for example, events with similar precursors. The higher the degree of homogeneity of the pool, then the Empirical Bayes estimator will be more accurate. We propose and evaluate a new method using homogenisation factors under the assumption that events are generated from a Homogeneous Poisson Process. The homogenisation factors are scaling constants, which can be elicited through structured expert judgement and used to align the frequencies of different events, hence homogenising the pool. The estimation error relative to the homogeneity of the pool is examined theoretically indicating that reduced error is associated with larger pool homogeneity. The effects of misspecified expert assessments of the homogenisation factors are examined theoretically and through simulation experiments. Our results show that the proposed Empirical Bayes method using homogenisation factors is robust under different degrees of misspecification.