Using activity theory to understand intergenerational play: The case of Family Quest

We implemented a five-week family program called Family Quest where parents and children ages 9 to 13 played Quest Atlantis, a multiuser 3D educational computer game, at a local after-school club for 90-minute sessions. We used activity theory as a conceptual and an analytical framework to study the nature of intergenerational play, the collaborative activity between parents and children in the context of role-playing virtual game environment, and the opportunities and challenges of bringing parents and children together around an educational video game. Our analyses of five parent-child dyads revealed that the nature of intergenerational play is different for different parent-child dyads, but has positive outcomes. Implications of the study for supporting family learning and bonding through video games are discussed.     

Nickel-cobalt-oxide cathodes for hydrogen production by water electrolysis in acidic and alkaline media

Mixed NiCo-oxide cathodes of various compositions were fabricated by a thermal-decomposition method and used as electrocatalysts for hydrogen production by water electrolysis in acidic and alkaline media. The oxide electrodes were found to be of a semi-crystalline structure, yielding the surface morphology characterized by a surface roughness factor going up to 25. Linear potentiodynamic and potentiostatic electrochemical measurements revealed that the Volmer reaction step controlled the kinetics of the hydrogen evolution on all the NiCo-oxide cathodes, and also on the pure metal Ni electrode (control). The Ni_0.2Co_0.8-oxide was identified as the best electrode material candidate among the investigated metal oxides, which was linked to the surface-area effect. However, its intrinsic activity was found to be lower than that of pure metallic Ni. Nevertheless, the Ni_0.2Co_0.8-oxide electrode showed a significantly higher electrocatalytic stability (fouling/deactivation tolerance) in comparison to metallic Ni.     

Oxide heterogrowth on ion-exfoliated thin-film complex oxide substrates

Fabrication of a bilayer HfO₂/single-crystal LiNbO₃ film is demonstrated using deep high-energy He⁺ implantation in a LiNbO₃ wafer, followed by HfO₂ atomic layer deposition, and, then, selective etching exfoliation from the bulk LiNbO₃ crystal. The properties and morphology of these exfoliated bilayer films are characterized using a set of thin-film probes. Pre-exfoliation film patterning and one model application, in surface-refractive-index tuning of guided waves in a free-standing LiNbO₃ film, are also demonstrated.     

The invisible benefits of exercise.

Objective: To examine whether—and why—people underestimate how much they enjoy exercise. Design: Across four studies, 279 adults predicted how much they would enjoy exercising, or reported their actual feelings after exercising. Main Outcome Measures: Main outcome measures were predicted and actual enjoyment ratings of exercise routines, as well as intention to exercise. Results: Participants significantly underestimated how much they would enjoy exercising; this affective forecasting bias emerged consistently for group and individual exercise, and moderate and challenging workouts spanning a wide range of forms, from yoga and Pilates to aerobic exercise and weight training (Studies 1 and 2). We argue that this bias stems largely from forecasting myopia, whereby people place disproportionate weight on the beginning of a workout, which is typically unpleasant. We demonstrate that forecasting myopia can be harnessed (Study 3) or overcome (Study 4), thereby increasing expected enjoyment of exercise. Finally, Study 4 provides evidence for a mediational model, in which improving people's expected enjoyment of exercise leads to increased intention to exercise. Conclusion: People underestimate how much they enjoy exercise because of a myopic focus on the unpleasant beginning of exercise, but this tendency can be harnessed or overcome, potentially increasing intention to exercise. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impact of a mild scrotal heat stress on DNA integrity in murine spermatozoa

An increase in scrotal temperature can lead to the production of poor quality spermatozoa and infertility. In the present study we have used mice to examine the impact of mild, scrotal heat stress (42 degrees C for 30 min) on numbers of spermatozoa as well as on the integrity of their DNA. Spermatozoa recovered from the epididymides hours (1 to 24) or days (7 to 32) after treatment were analysed using COMET and sperm chromatin structure (SCSA) assays. The treatment induced a stress response in both the testis and the epididymis that was associated with reduced expression of the cold inducible RNA binding protein (Cirp) and an increase in germ cell apoptosis (Apotag positive cells). Although spermatozoa present in the epididymis at the time of heating contained correctly packaged DNA, its integrity was compromised by heat stress. In addition, although some germ cells, which were present within the testis at the time of heat stress, were removed by apoptosis, many germ cells completed their development and were recovered as motile spermatozoa with damaged DNA. In conclusion, these data demonstrate that scrotal heat stress can compromise the DNA integrity of spermatozoa and this may have clinical implications for patients undergoing IVF and intra-cytoplasmic sperm injection (ICSI).     

Self-citation: comparison between Radiology,European Radiology and Radiology for 1997–1998

This study investigates the incidence of self-citation (authors citing their own work) for scholarly articles in ten journals published by the American Physiological Society. We analysed authorship and referencing practices of all original research articles published in the first ordinary issue of each journal in both 2000 and 2010, comprising 271 and 212 articles, respectively. Self-citation is common in these journals and represents a total of 17.75% of all citations. Only 9 (1.86%) of the articles analysed did not self-cite. Author position significantly influenced the rate of self-citation with last authors being self-cited significantly more than any other author. This was likely a result of the cumulative nature of scientific research within a specific discipline and the necessary desire to promote ones own work for associated academic benefit. The country in which the work was conducted also influenced the rate of self-citation, with last authors based in North America self-citing more than last authors from Asian countries. A comparison of self-citation rates between decades (2000 and 2010) revealed an increase in the number of authors and number of citations per article between 2000 and 2010, however the mean percentage of self-cited articles did not differ between the years. Finally, there were no differences in the percentage of self-citation between the different journals analysed.     

Oxidase activity of the acyl-CoA dehydrogenases

The medium chain acyl-CoA dehydrogenase catalyzes the flavin-dependent oxidation of a variety of acyl-CoA thioesters with the transfer of reducing equivalents to electron-transferring flavoprotein. The binding of normal substrates profoundly suppresses the reactivity of the reduced enzyme toward molecular oxygen, whereas the oxidase reaction becomes significant using thioesters such as indolepropionyl-CoA (IP-CoA) and 4-(dimethylamino)-3-phenylpropionyl-CoA (DP-CoA). Steady-state and stopped-flow studies with IP-CoA led to a kinetic model of the oxidase reaction in which only the free reduced enzyme reacts with oxygen (Johnson, J. K., Kumar, N. R., and Srivastava, D. K. (1994) Biochemistry 33, 4738-4744). We have tested their proposal with IP-CoA and DP-CoA. The dependence of the oxidase reaction on oxygen concentration is biphasic with a major low affinity phase incompatible with a model predicting a simple Km for oxygen of 3 microM. If only free reduced enzyme reacts with oxygen, increasing IP-CoA would show strong substrate inhibition because it binds tightly to the reduced enzyme. Experimentally, IP-CoA shows simple saturation kinetics. The Glu376-Gln mutant of the medium chain dehydrogenase allows the oxygen reactivity of complexes of the reduced enzyme with IP-CoA and the corresponding product indoleacryloyl-CoA (IA-CoA) to be characterized without the subsequent redox equilibration that complicates analysis of the oxidase kinetics of the native enzyme. In sum, these data suggest that when bulky, nonphysiological substrates are employed, multiple reduced enzyme species react with molecular oxygen. The relatively high oxidase activity of the short chain acyl-CoA dehydrogenase from the obligate anaerobe Megasphaera elsdenii was studied by rapid reaction kinetics of wild-type and the Glu367-Gln mutant using butyryl-, crotonyl-, and 2-aza-butyryl-CoA thioesters. In marked contrast to those of the mammalian dehydrogenase, complexes of the reduced bacterial enzyme with these ligands react with molecular oxygen at rates similar to those of the free protein. Evolutionary and mechanistic aspects of the suppression of oxygen reactivity in the acyl-CoA dehydrogenases are discussed.     

Dendrimer-entrapped gold nanoparticles as a platform for cancer-cell targeting and imaging

We present a general approach for the targeting and imaging of cancer cells using dendrimer-entrapped gold nanoparticles (Au DENPs). Au DENPs were found to be able to covalently link with targeting and imaging ligands for subsequent cancer-cell targeting and imaging. The Au DENPs linked with defined numbers of folic acid (FA) and fluorescein isothiocyanate (FI) molecules are water soluble, stable, and biocompatible. In vitro studies show that the FA- and FI-modified Au DENPs can specifically bind to KB cells (a human epithelial carcinoma cell line) that overexpress high-affinity folate receptors and they are internalized dominantly into lysosomes of target cells within 2 h. These findings demonstrate that Au DENPs may serve as a general platform for cancer imaging and therapeutics.     

Planning trajectories in post-socialist cities: patterns of divergence and change

This article explores the new planning regimes and planning processes in post-socialist countries and their ability to influence the spatial transformation of cities. It views planning institutions as culturally embedded in the overall process of economic, social, and political transition, while recognizing the power of specific local imperatives and market pressures to shape their response. The research draws on empirical evidence in four countries and their capital cities to highlight the links between the transition to democracy, markets, and decentralized governance on the spatial transformation in post-socialist cities. The main argument is that the new planning institutions have different ability to direct these processes of change, depending on the legal framework, the availability of plans, and the institutionalization of the plan-implementation process. Despite the diverse mosaic of urban experiences in Prague, Riga, Belgrade, and Tirana, planning institutions are viewed as path dependent, influenced by a common socialist legacy. Further, changes in the exogenous environment – economic, social, and institutional – are perceived to be important sources of convergence, but tend to shape different planning responses and policy choices. The research explores these differences as well as the new patterns of spatial transformation in three principal domains: (1) spaces of production/consumption reflecting the economic transition; (2) differentiation in residential spaces associated with the social transition; and (3) new approaches to planning and service delivery resulting from the transition in governance. Central to the arguments in the article is that transition of this magnitude has created a complex urban world in which the patterns of divergence are going to become more explicit in the future, producing spatial and temporal differentiation among post-socialist cities.