Age differences in item manipulation span: The case of letter-number sequencing.

The authors report 2 experiments in which they examined age differences in working memory tasks involving complex item manipulation (i.e., letter-number sequencing). In Experiment 1, age differences on tasks involving item manipulation were not greater than age differences on tasks requiring recall of items in the order in which they appeared, suggesting that older adults do not have difficulty with item manipulation per se. In Experiment 2, slower presentation rates increased age differences in item manipulation spans, although age differences at the fastest rate may be attributed to differences in strategy use. In both experiments, age differences were largest when participants were most likely to be remembering familiar sequences, suggesting that older adults may have difficulties dampening the representations of such sequences once they are activated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Longitudinal factor structure of posttraumatic stress symptoms related to intimate partner violence.

Confirmatory factor analysis (CFA) studies have suggested that a model of posttraumatic stress disorder (PTSD) that is characterized by 4 factors is preferable to competing models. However, the composition of these 4 factors has varied across studies, with 1 model splitting avoidance and numbing symptoms (e.g., D. W. King, G. A. Leskin, L. A. King, & F. W. Weathers, 1998) and the other including a dysphoria factor that combines numbing and nonspecific hyperarousal symptoms (L. J. Simms, D. Watson, & B. N. Doebbeling, 2002). Using the PTSD Checklist (F. W. Weathers, B. T. Litz, D. S. Herman, J. A. Huska, & T. M. Keane, 1993) and CFA, the authors compared these models with competing models. A model of PTSD with 4 intercorrelated factors of Intrusions, Avoidance, Dysphoria, and Hyperarousal was found superior among 396 medical patients who screened positive for intimate partner violence (IPV) and 405 women seeking services for IPV. Structural invariance testing indicated that this 4-factor model remains stable across service setting and time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adhesive forces significantly affect elastic modulus determination of soft polymeric materials in nanoindentation

The present study investigated the effects of adhesion on the elastic modulus determined from nanoindentation curves for soft polydimethylsiloxane (PDMS) elastomers with five different crosslink concentrations. Indentation load-displacement curves were obtained for samples of all concentrations at four different peak loads. All load-displacement curves were nearly linear, resulting in load independent contact stiffnesses (p < 0.003) for the range of loads tested. As a result, elastic modulus calculated from nanoindentation curves with the Hertz contact model exhibited significant differences (p < 0.004) both at different peak loads for a single PDMS concentration and between different PDMS concentrations at a single peak load (p < 0.001). The differences for different peak loads were attributed to the presence of substantial adhesive forces at the tip-sample interface. By taking these adhesive interactions into account with the Johnson, Kendall, Roberts (JKR) contact model, the differences in elastic modulus at different peak loads could be reconciled. Significant differences (p < 0.001) in moduli between different PDMS concentrations were still present. The results highlight the importance of considering adhesive forces in nanoindentation analyses of low modulus polymeric materials.     

散落在云南的日子

阳光下,圣洁的雪峰屹立着古老的沧桑,现代的神秘,让我一如既往地憧憬那天边的金色殿堂。大假。约驴友共赴春城。除了路途颠簸的两整天,剩余的八个日子有如繁星,轻轻地散落在云南的各个角落,以至长时间里几度提笔,也不曾找到自己被     

Remote electronic voting systems: an exploration of voters' perceptions and intention to use

Coupling telephone and web interfaces with computers for balloting outside the polling place, remote electronic voting systems (REVS) give the voter a choice: polling booth, absentee ballot, or remote voting. Not only does this e-Government technology raises issues such as security, voter participation, and accessibility, REVS technologies themselves differ in features and enabling conditions. How users (voters) perceive REVS's availability, mobility, accuracy, privacy protection, and ease of use, is likely to affect their use intention. Intention to use or not to use a voting technology can translate into a decision to vote or not – and there are no ‘do-overs’. We develop a model and report on a survey of potential voters – people waiting to be impaneled on a jury – in regard to the impact of REVS characteristics on voting intentions and how the two most discussed REVS technologies of telephone- and web-based interfaces are perceived.     

The optimal level of fuzz: case studies in a methodology for psychological research

Cognitive science research is hard to conduct, because researchers must take phenomena from the world and turn them into laboratory tasks for which a reasonable level of experimental control can be achieved. Consequently, research necessarily makes tradeoffs between internal validity (experimental control) and external validity (the degree to which a task represents behaviour outside of the lab). Researchers are thus seeking the best possible trade-off between these constraints, which we refer to as the optimal level of fuzz. We present two principles for finding the optimal level of fuzz, in research, and then illustrate these principles using research from motivation, individual differences and cognitive neuroscience.     

WAVELET-BASED STEGANOGRAPHY

Wavelets, which are used to separate data into different components, have many applications. Steganography, one such application, is a form of secret communication where the existence of a message is concealed. Methods for applying univariate and bivariate wavelets to steganography include embedding messages into the insignificant wavelet coefficients of decomposed signals and images. Recomposing then creates stego-objects that appear unaltered from the original cover-objects. First demonstrated is a technique for hiding messages in strings of data with linear trends using the univariate Daubechies D ₄ wavelets. Then, after developing the bivariate Haar wavelets and filters, a unique process of decomposing and recomposing an image in greyscale in order to implement steganography will be illustrated.     

Using digital cameras for river plume and water quality measurements

The results from a pilot study in coastal waters off the east coast of Ireland using both an in situ and airborne mounted digital camera are described. In situ digital pictures are significantly affected by sea surface reflection. This can be eliminated with the use of a hollow pipe, attached to the camera lens, which intersects the sea surface such that a picture of light upwelled from beneath the surface is obtained. Used in this way, linear relations between both the ratio of red/green digital output (O/P) values (at a particular camera exposure) and the difference in green–red digital camera O/P were found with mineral suspended solid (MSS) concentration. A good comparison was also found between the ratios of red/green upwelling light measured with the camera and a conventional irradiance sensor. Semi‐empirical or analytical relationships between camera O/P and the inherent optical properties of the water could not be established, however. This was probably due, in part, to a lack of range in values for the water constituent parameters. An airborne mounted digital camera was used to successfully monitor the dynamics of a river plume discharging into the coastal water. The high dissolved organic material (CDOM) levels within the plume caused the plume to be easily visible in the digital imagery, with a significantly increased signal in the camera's red/green O/P values marking the spatial extent of the plume. The plume dynamics were principally controlled by the tidal flows in the coastal waters. During the ebb tide strong fronts, and inferred convergence zones, marked the edge of the river plume and were associated with increased values of the camera‐derived red/green ratio. As slack water commenced, the plume expanded away from the source and became thinner, with a decreased red/green signal. Associated with this time internal fronts were present within the plume's extent, marked by step changes, or spikes, in the camera's red/green values.