The effect of interactive technology on informal learning and performance in a social setting

This study is based on a qualitative multiple case study research design using a mixed methods approach to provide insight into the effect of interactive technology on informal learning and performance in a social business setting inhabited by knowledge workers. The central phenomenon examined is the variance in behavioral intention towards interactive Web 2.0 technologies in learning and performance-related activities, depending on social and cultural setting, observable in individual and group usage patterns. The theoretical foundation for this study is drawn primarily from the activity theory model developed by Engeström (1987) and related research enabled by an ongoing review of the literature. Two new research frameworks have been developed and presented in the analysis and discussion chapters, respectively, of this study: 1.) A three-stage framework for data analysis in qualitative research; and 2.) A matrix of mutually exclusive categorical themes affecting behavioral intention, aligned with primary and secondary mediators of activity identified in the activity theory model. Current research covering activity theory and workplace learning, and implications for social learning related to performance has been synthesized with the findings from this study, and included in the discussion chapter. The results of this study demonstrate that there are six identifiable mediators of activity tied to informal learning and performance in an organizational setting. The mediators identified are: tools, rules, division of labor, collaboration, cultural/social setting, and personal perception of role. These mediators were derived from the activity theory model and subsequently addressed by the research questions using an in-depth interview protocol. Existing research models for behavioral intention in technology acceptance were also applied, producing a validated survey instrument that yielded a set of mutually exclusive categorical themes for analysis of categories associated with each research question during the analysis phase of the study. The categorical themes shown to have an affect on behavioral intention are: performance expectancy, effort expectancy, explicit social influence, facilitating conditions, and implicit social influence. The net result is a framework for analyzing human performance that aligns each of the categorical themes shown to affect behavioral intention within each of the mediators for activity, based on an activity systems view of informal learning and performance. Further research is needed to validate these constructs by studying activity systems within other organizational and institutional settings

High-Contrast 3.8 Micron Imaging Of The Brown Dwarf/Planet-Mass Companion to GJ 758

We present L' band (3.8 $\mu m$) MMT/Clio high-contrast imaging data for the nearby star GJ 758, which was recently reported by Thalmann et al. (2009) to have one -- possibly two-- faint comoving companions (GJ 758B and ``C", respectively). GJ 758B is detected in two distinct datasets. Additionally, we report a \textit{possible} detection of the object identified by Thalmann et al as ``GJ 758C" in our more sensitive dataset, though it is likely a residual speckle. However, if it is the same object as that reported by Thalmann et al. it cannot be a companion in a bound orbit. GJ 758B has a H-L' color redder than nearly all known L--T8 dwarfs. Based on comparisons with the COND evolutionary models, GJ 758B has T$_{e}$ $\sim$ 560 K$^{^{+150 K}_{-90K}}$ and a mass ranging from $\sim$ 10--20 M$_{J}$ if it is $\sim$ 1 Gyr old to $\sim$ 25--40 M$_{J}$ if it is 8.7 Gyr old. GJ 758B is likely in a highly eccentric orbit, e $\sim$ 0.73$^{^{+0.12}_{-0.21}}$, with a semimajor axis of $\sim$ 44 AU$^{^{+32 AU}_{-14 AU}}$. Though GJ 758B is sometimes discussed within the context of exoplanet direct imaging, its mass is likely greater than the deuterium-burning limit and its formation may resemble that of binary stars rather than that of jovian-mass planets.Comment: 14 pages, 3 figures. Accepted for publication in The Astrophysical Journal Letter

Fish growth changes over time in a Midwestern USA lake

Growth of Walleye Sander vitreus, Yellow Bass Morone mississippiensis, Common Carp Cyprinus carpio, and Black Bullhead Ameiurus melas was assessed in Clear Lake, Iowa, USA, over several decades and in relation to environmental variables. Growth of Common Carp was positively correlated with phytoplankton concentration. Recent Black Bullhead growth was faster than in the 1950s and 1990s, which may be a consequence of their recent decline in abundance. Growth of Common Carp and Yellow Bass was faster in the 1940s than in more recent time periods. Relative to their entire range, Common Carp first year growth was below average whereas length at later ages was above average. Walleye relative growth showed a similar pattern. The large changes in growth over several decades suggest that as the Clear Lake ecosystem continues to change, growth rates of its important fish species are also likely to continue changing

Ray representation of sound scattering by weakly scattering deformed fluid cylinders : simple physics and application to zooplankton

Author Posting. © Acoustical Society of America, 1993. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 94 (1993): 3454-3462, doi:10.1121/1.407199.Data indicate that certain important types of marine organisms behave acoustically like weakly scattering fluid bodies (i.e., their material properties appear fluidlike and similar to those of the surrounding fluid medium). Use of this boundary condition, along with certain assumptions, allows reduction of what is a very complex scattering problem to a relatively simple, approximate ray-based solution. Because of the diversity of this problem, the formulation is presented in two articles: this first one in which the basic physics of the scattering process is described where the incident sound wave is nearly normally incident upon a single target (i.e., the region in which the scattering amplitude is typically at or near a maximum value for the individual) and the second one [Stanton et al., J. Acoust. Soc. Am. 94, 3463–3472 (1993)] where the formulation is heuristically extended to all angles of incidence and then statistically averaged over a range of angles and target sizes to produce a collective echo involving an aggregation of randomly oriented different sized scatterers. In this article, a simple ray model is employed in the deformed cylinder formulation [Stanton, J. Acoust. Soc. Am. 86, 691–705 (1989)] to describe the scattering by finite length deformed fluid bodies in the general shape of elongated organisms. The work involves single realizations of the length and angle of orientation. Straight and bent finite cylinders and prolate spheroids are treated in separate examples. There is reasonable qualitative comparison between the structure of the data collected by Chu et al. [ICES J. Mar. Sci. 49, 97–106 (1992)] involving two decapod shrimp and this single-target normal-incidence theory. This analysis forms the basis for successful comparison (presented in the companion article) between the extended formulation that is averaged over an ensemble of realizations of length and angle of orientation and scattering data involving aggregations of up to 100's of animals.This work was supported by the U.S. Office of Naval Research Grant No. N00014-89-J-1729 and National Science Foundation Grant No. OCE-8817171

Effects of Grade Control Structures on Fish Passage, Biological Assemblages and Hydraulic Environments in Western Iowa Streams: A Multidisciplinary Review

Land use changes and channelization of streams in the deep loess region of western Iowa have led to stream channel incision, altered flow regimes, increased sediment inputs, decreased habitat diversity and reduced lateral connectivity of streams and floodplains. Grade control structures (GCSs) are built in streams to prevent further erosion, protect infrastructure and reduce sediment loads. However, GCS can have a detrimental impact on fisheries and biological communities. We review three complementary biological and hydraulic studies on the effects of GCS in these streams. GCS with steep (≥1:4 rise : run) downstream slopes severely limited fish passage, but GCS with gentle slopes (≤1:15) allowed greater passage. Fish assemblages were dominated by species tolerant of degradation, and Index of Biotic Integrity (IBI) scores were indicative of fair or poor biotic integrity. More than 50% of fish species had truncated distributions. After modification of GCS to reduce slopes and permit increased passage, IBI scores increased and several species were detected further upstream than before modification. Total macroinvertebrate density, biomass and taxonomic diversity and abundance of ecologically sensitive taxa were greater at GCS than in reaches immediately upstream, downstream or ≥1 km from GCS. A hydraulic study confirmed results from fish passage studies; minimum depths and maximum current velocities at GCS with gentle slopes (≤1:15) were more likely to meet minimum criteria for catfish passage than GCS with steeper slopes. Multidisciplinary approaches such as ours will increase understanding of GCS-associated factors influencing fish passage, biological assemblage structure and other ecological relationships in streams

Average echoes from randomly oriented random-length finite cylinders : zooplankton models

Author Posting. © Acoustical Society of America, 1993. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 94 (1993): 3463-3472, doi:10.1121/1.407200.By heuristically extending the previously developed ray solution [Stanton et al. J. Acoust. Soc. Am. 94, 3454–3462 (1993)] to predict the scattering by cylinders over all angles of incidence, approximate expressions are derived which describe the echo energy due to sound scattered by finite cylinders averaged over orientation and length. Both straight and bent finite length cylinders of high aspect ratio are considered over the full range of frequencies (Rayleigh through geometric scattering). The results show that for a sufficiently broad range of orientation, the average echo is largely independent of the degree of bend—that is, the results are essentially the same for both the straight and bent cylinders of various radii of curvature (provided the bend is not too great). Also, in the limit of high frequency (i.e., the acoustic wavelength is much smaller than the cross-sectional radius of the object), the averages are independent of frequency. The resultant formulas derived herein are useful in describing the scattering by elongated zooplankton whose shape may not necessarily be known in the natural ocean environment. The average echo is shown to depend directly upon standard deviation (s.d.) of the angle of orientation as well as size. If independent measurements of size are made (such as from trawling samples), then the properties of the angle distribution and hence behavior may be inferred from the data. Averages over both angle and a narrow distribution of size are shown to only partially smooth out deep nulls in the scatter versus frequency curves. The formulas compare favorably with laboratory data involving aggregations of animals and a broad range of frequencies (38 kHz to 1.2 MHz).This research was supported by the Oceanic Biology and Ocean Acoustics Programs of the U.S. Office of Naval Research Grant No. N00014-89-J-1729 and the Office of Naval Technology (through the U.S. Naval Undersea Warfare Center, Newport, Contract No. N66604- 91-C-5401)

Violence Increases Psychological Distress Among Women Trafficking Survivors in Ghana

Human trafficking is a crime that is often shaped by violence, particularly for women who are trafficked. Additionally, trafficking survivors often report severe psychological distress, though research on the causes of this psychological distress is lacking, as there is little longitudinal data available on trafficking survivors. Informed by past literature on the links between violence and mental health among other traumatized groups of women, we investigate how experiences of violence influence posttraumatic stress, depression, and suicide ideation among a unique longitudinal sample of 116 labor-trafficked women in Ghana. We find that experiencing sexual violence while being trafficked is associated with higher levels of both depression and posttraumatic stress years after the trafficking period ended. This indicates both the long-term effects of stress and the enduring nature of psychological distress among the women in this study. Our analytic account of how violent experiences while trafficked impact mental health over the period of reintegration contributes to the general literature on violence and mental health among women, as well as to literature on the health implications of human traffickin