Human navigation in nested environments.

Navigation in humans and many other animals relies on spatial representations of their environments. Three experiments examined how humans maintain sense of orientation between nested environments. Subjects can acquire new spatial representations easily without integrating them into their existing spatial knowledge system. While navigating between nested environments, subjects seemed to constantly switch between the currently processed environment by reorienting to approaching environments and losing track of old environments at given spatial regions. These results suggest that spatial updating in naturalistic, nested environments does not occur for all environments at the same time. Implications for the hierarchical theory of spatial representations and the path integration theory of navigation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human Resource Management for Continuous Improvement

This paper investigates the relationship between HRM practices and Continuous Improvement (CI) activities in order to gain an understanding of how the HRM function may be utilized to improve CI implementation success, and consequently, company performance. The paper begins with a brief review of the HRM and CI literature and then presents statistical analyses of data collected from the Continuous Improvement Network Survey (2003), which demonstrate that HRM has a significant effect on CI behaviour and company performance, with the strongest relationship between HRM, CI and performance occurring when companies align their CI activities with their strategic objectives and use systems, procedures and processes to measure the results of their CI activities.     

Quantitative effects of acquisition duration and temporal resolution on the measurement accuracy of prostate dynamic contrast-enhanced MRI data: a phantom study

Objectives

The aim of this study was to investigate the effect of the temporal resolution (T _res) and acquisition duration (AD) on the measurement accuracy of contrast concentration–time curves (CTCs), and derived phenomenological and pharmacokinetic parameter values, in a dynamic contrast-enhanced MRI experiment using a novel phantom test device.

Materials and methods

‘Ground truth’ CTCs were established using a highly precise optical imaging system. These precisely known CTCs were produced in an anthropomorphic environment, which mimicked the male pelvic region, and presented to the MRI scanner for measurement. The T _res was varied in the range [2–24.4 s] and the AD in the range [30–600 s], and the effects on the measurement accuracy were quantified.

Results

For wash-in parameter measurements, large underestimation errors (up to 40%) were found using T _res values ≥16.3 s; however, the measured wash-out rate did not vary greatly across all T _res values tested. Errors in derived K ^trans and v _e values were below 14 and 12% for acquisitions with {T _res ≤ 8.1 s, AD ≥ 360 s} and {T _res ≤ 16.3 s, AD ≥ 360 s}, respectively, but increased dramatically outside these ranges.

Conclusions

Errors in measured wash-in, wash-out, K ^trans, and v _e parameters were minimised using T _res ≤ 8.1 s and AD ≥ 360 s, with large errors recorded outside of this range.

     

Partially observed epidemics in wildlife hosts: modelling an outbreak of dolphin morbillivirus in the northwestern Atlantic,June 2013–2014

Morbilliviruses cause major mortality in marine mammals, but the dynamics of transmission and persistence are ill understood compared to terrestrial counterparts such as measles; this is especially true for epidemics in cetaceans. However, the recent outbreak of dolphin morbillivirus in the northwestern Atlantic Ocean can provide new insights into the epidemiology and spatio-temporal spread of this pathogen. To deal with uncertainties surrounding the ecology of this system (only stranded animals were observed), we develop a statistical framework that can extract key information about the underlying transmission process given only sparse data. Our self-exciting Poisson process model suggests that individuals are infectious for at most 24 days and can transfer infection up to two latitude degrees (220 km) within this time. In addition, the effective reproduction number is generally below one, but reaches 2.6 during a period of heightened stranding numbers near Virginia Beach, Virginia, in summer 2013. Network analysis suggests local movements dominate spatial spread, with seasonal migration facilitating wider dissemination along the coast. Finally, a low virus transmission rate or high levels of pre-existing immunity can explain the lack of viral spread into the Gulf of Mexico. More generally, our approach illustrates novel methodologies for analysing very indirectly observed epidemics.     

Issues in the development of reliable measures in addiction research: Introduction to Project MATCH assessment strategies.

This article provides an introduction to the 5 instrument articles in this special section, each of which presents a psychometric evaluation of a self-administered questionnaire developed for use in addictions treatment research. An overview of measurement theory is presented, and social-psychological factors that affect reliability and validity are considered. The instruments evaluated in this issue are summarized, and the 2 common data sources for the 5 reports, the Project MATCH baseline data set and the Project MATCH Reliability Study, are described. The article concludes with a brief summary that offers recommendations regarding how psychometric investigation should be undertaken and applied to the development of self-report questionnaires in addictions research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rheological behaviour and related granulometric properties of dense aggregated suspensions during an ultrafine comminution process

The rheological behaviour of calcite suspensions made of particles with different size distributions, obtained by means of a wet comminution process, have been studied versus the operating conditions (volume concentration, use of dispersing agent). The suspension properties (size distribution, specific surface area [SSA]) were investigated in order to characterize the microstructure of the aggregated suspensions. The suspension acts as a thinning fluid with a yield value, and the viscosity increases when the particle size decreases (colloidal dispersions) due to attractive interparticle forces. The use of a polyelectrolyte (sodium polyacrylate [SPA]) during the size-reduction process allows strong reduction of the viscosity of the ground suspensions. The polymer is adsorbed onto the surface of the particles and, consequently, prevents aggregation and allows improvement of the process efficiency.     

Protective and risk factors in health-enhancing behavior among adolescents in china and the United States: Does social context matter?

An explanatory model of adolescent health-enhancing behavior based on protective and risk factors at the individual level and in 4 social contexts was used in a study of school-based samples from the People's Republic of China (n = 1,739) and the United States (n = 1,596). A substantial account of variation in health-enhancing behavior--and of its developmental change over time--was provided by the model for boys and girls, and for the 3 grade cohorts, in both samples. In both samples, social context protective and risk factors accounted for more unique variance than did individual-level protective and risk factors, and context protection moderated both contextual and individual-level risk. Models protection and controls protection were of particular importance in the explanatory account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

awaywithwords: On the possibilities in unavailable designs

Constraints in our use of communication materials are often socially and historically produced; to ask after the constraints as we teach or compose can help us understand how material choices in producing communications articulate to social practices we may not otherwise wish to reproduce. In this writing, I consider the constraints Gunther Kress often applied to “word” and “image,” questioning their temporal and spatial structures.     

An A to Z guide to DSM-IV conundrums.

The work on the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) poses many puzzling conundrums that touch on complicated and important theoretical and practical issues. None of these can be resolved in the DSM-IV, but the authors hope that the Task Force's decisions will be informed by thorough reviews of the currently available evidence and extensive input from all sectors of the mental health field. A. J. Frances et al provide an alphabetical guide to DSM-IV conundrums that they hope will stimulate comments, suggestions, and criticisms about the work of the Task Force. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depression and gender: An international review.

This article reviews and updates major research findings on depressive disorders and gender relationships in the United States and abroad. It also considers some of the World Health Organization's assessment instruments that may clarify the relationship between depression and gender and its cross-cultural ramifications. With psychology converging across national boundaries and with gender being a variable in psychological research both nationally and internationally, gender and its relationship to depressive states is emerging as a focal point of interest and concern. (PsycINFO Database Record (c) 2010 APA, all rights reserved)