Are digital natives a myth or reality? University students’ use of digital technologies

This study investigated the extent and nature of university students’ use of digital technologies for learning and socialising. The findings show that students use a limited range of mainly established technologies. Use of collaborative knowledge creation tools, virtual worlds, and social networking sites was low. ‘Digital natives’ and students of a technical discipline (Engineering) used more technology tools when compared to ‘digital immigrants’ and students of a non-technical discipline (Social Work). This relationship may be mediated by the finding that Engineering courses required more intensive and extensive access to technology than Social Work courses. However, the use of technology between these groups is only quantitatively rather than qualitatively different. The study did not find evidence to support popular claims that young people adopt radically different learning styles. Their attitudes to learning appear to be influenced by lecturers’ teaching approaches. Students appear to conform to traditional pedagogies, albeit with minor uses of tools delivering content. The outcomes suggest that although the calls for transformations in education may be legitimate it would be misleading to ground the arguments for such change in students’ shifting patterns of learning and technology use.     

Melanocytes Affect Nodal Expression and Signaling in Melanoma Cells: A Lesson from Pediatric Large Congenital Melanocytic Nevi

Expression of Nodal, a Transforming Growth Factor-beta (TGF-β) related growth factor, is associated with aggressive melanoma. Nodal expression in adult dysplastic nevi may predict the development of aggressive melanoma in some patients. A subset of pediatric patients diagnosed with giant or large congenital melanocytic nevi (LCMN) has shown increased risk for development of melanoma. Here, we investigate whether Nodal expression can help identify the rare cases of LCMN that develop melanoma and shed light on why the majority of these patients do not. Immunohistochemistry (IHC) staining results show varying degree of Nodal expression in pediatric dysplastic nevi and LCMN. Moreover, median scores from Nodal IHC expression analysis were not significantly different between these two groups. Additionally, none of the LCMN patients in this study developed melanoma, regardless of Nodal IHC levels. Co-culture experiments revealed reduced tumor growth and lower levels of Nodal and its signaling molecules P-SMAD2 and P-ERK1/2 when melanoma cells were grown in vivo or in vitro with normal melanocytes. The same was observed in melanoma cells cultured with melanocyte conditioned media containing pigmented melanocyte derived melanosomes (MDM). Since MDM contain molecules capable of inactivating radical oxygen species, to investigate potential anti-oxidant effect of MDM on Nodal expression and signaling in melanoma, melanoma cells were treated with either N-acetyl-l-cysteine (NAC), a component of the anti-oxidant glutathione or synthetic melanin, which in addition to providing pigmentation can also exert free radical scavenging activity. Melanoma cells treated with NAC or synthetic melanin showed reduced levels of Nodal, P-SMAD2 and P-ERK1/2 compared to untreated melanoma cells. Thus, the potential role for Nodal in melanoma development in LCMN is less evident than in adult dysplastic nevi possibly due to melanocyte cross-talk in LCMN capable of offsetting or delaying the pro-melanoma effects of Nodal via anti-oxidant effects of MDM.     

Dependence of thermo-mechanical and mechanical properties of novel fluorophosphate glass on various rare earth dopants

The dependence of thermo-mechanical, and mechanical properties on various rare earth dopants (RE) including Nd₂O₃, Er₂O₃, and Yb₂O₃ in 0.4MgF₂-0.4BaF₂-0.1Ba(PO₃)₂-0.1Al(PO₃)₃ glasses (MBBA system) is systematically investigated. MBBA system doped with RE dopants presented the potential application in the field of communication and high power layer system in the previous reports. In this work, it is found that the density of the doped glass increases with an increasing of RE concentration, which could be understood in terms of cationic field strength (CFS) effect. The Knoop hardness is found to decrease with the loading time and dopant concentration due to the indentation size effect (ISE) effect. The observed decrease of thermal expansion coefficient and the increase of glass transition temperature T _g with increasing dopant concentration are elucidated in terms of the increasing number of strong covalent bonds with increasing RE dopant concentration. Those results will be of paramount importance before designing optical devices.     

Male-Produced Pheromone of the Green Lacewing, Chrysopa nigricornis

Gas chromatographic–electroantennographic detection (GC–EAD) analysis showed that male antennae of the green lacewing, Chrysopa nigricornis Burmeister, the most common lacewing species in the U.S. Pacific Northwest, consistently responded to two compounds in thoracic extracts of conspecific males: 1-tridecene and (1R,2S,5R,8R)-iridodial. These compounds were not detected in extracts of the abdominal cuticle, and no other antennally active compounds were found in the abdominal samples. In field-trapping experiments, traps baited with iridodial significantly attracted large numbers of C. nigricornis males (both western and eastern forms) during summer and early fall, plus a few individuals of conspecific females only in early fall. Iridodial also attracted males of the goldeneyed lacewing, C. oculata Say, and, to a lesser extent, C. coloradensis Banks males. Methyl salicylate (MS), reported as an attractant for both sexes of C. nigricornis and C. oculata, was inactive by itself at the concentration tested in our study, but in a few instances slightly enhanced the responses of Chrysopa spp. to iridodial. However, MS alone and its binary blend with iridodial seemed to attract the hoverfly, Metasyrphus americanus (Weidemann). 2-Phenylethanol, a reported attractant for another lacewing, Chrysoperla plorabunda (Fitch) [=carnea (Say)], did not capture any lacewings. Our assays indicated that the lacewing pheromone, iridodial, loaded onto either rubber septa or as a binary blend with MS in polyethylene bags could last at least 5 wk in the field during the summer season. Based on this study, a new attractant system for green lacewings is being developed for both domestic and international markets.     

Spectroscopic properties of Yb in heavy metal contained fluorophosphate glasses

A new series of 20Bi(PO₃)₃–10Sr(PO₃)₂–35BaF₂–35MgF₂ doped with Yb³⁺ is introduced for fiber and waveguide laser applications. The stimulated emission cross-section σ_emi, which was found to be 1.37 pm² at the lasing wavelength of 996 nm, is the highest one among fluorophosphate glasses. It has been found that an extremely high gain coefficient of G = 1.65 ms pm⁴ and high quantum efficiency of η = 93% for 1 wt.% Yb₂O₃ doped systems. The various concentration effects on laser performance properties including minimum pumping intensity I_min, the minimum fraction of excited ions β_min and the saturation pumping intensity I_sat are analyzed as a function of Yb₂O₃ concentration. Those results obtained in current system had advantage over some fluorophosphate glasses reported.     

Novel alkaline-free Er-doped fluorophosphate glasses for broadband optical fiber lasers and amplifiers

Two sets of Er³⁺-doped alkaline-free glass systems, MgF₂–BaF₂–Ba(PO₃)₂–Al(PO₃)₃ (MBBA) and Bi(PO₃)₃–Ba(PO₃)₂–BaF₂–MgF₂ (BBBM), have been prepared and investigated with the aim of using them as active media. Radiative lifetimes (τ_rad) and branching ratios (β) have been obtained for the excited states of Er³⁺. The absorption spectra were recorded to obtain the intensity parameters (Ω_t) which are found to be Ω₂ = 4.47 × 10⁻²⁰ cm², Ω₄ = 1.31 × 10⁻²⁰ cm², Ω₆ = 0.81 × 10⁻²⁰ cm² for the MBBA system and Ω₂ = 4.03 × 10⁻²⁰ cm², Ω₄ = 1.34 × 10⁻²⁰ cm², Ω₆ = 0.53 × 10⁻²⁰ for the BBBM system, respectively. The emission cross-section for the ⁴I_13/2 → ⁴I_15/2 transition is determined by the Fuchtbauer–Ladenburg method and found to be 2.35 × 10⁻²⁰ cm² and 3.54 × 10⁻²⁰ cm² for the MBBA and BBBM system, respectively. Comparison of the measured values to those of Er³⁺ transitions in other glass hosts suggests that our new glass systems are good candidates for broadband compact optical fiber and waveguide amplifier applications.     

Effects of β-amyloid (1-42) Administration on the Main Neurogenic Niches of the Adult Brain: Amyloid-Induced Neurodegeneration Influences Neurogenesis

Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder and warrants further study as well as timely treatment. Additionally, the mechanisms of the brain’s intrinsic defense against chronic injury are not yet fully understood. Herein, we examined the response of the main neurogenic niches to amyloid exposure and the associated changes in structure and synaptic activity. Flow cytometry of Nestin-, Vimentin-, Nestin/Vimentin-, NeuN-, GFAP-, NeuN/GFAP-, NSE-, BrdU-, Wnt-, BrdU/Wnt-, VEGF-, Sox14-, VEGF/Sox14-, Sox10-, Sox2-, Sox10/Sox2-, Bax-, and Bcl-xL-positive cells was performed in the subventricular zone (SVZ), hippocampus, and cerebral cortex of rat brains on 90th day after intracerebroventricular (i.c.v.) single injection of a fraction of β-amyloid (Aβ) (1-42). The relative structural changes in these areas and disruptions to synaptic activity in the entorhinal cortex–hippocampus circuit were also evaluated. Our flow analyses revealed a reduction in the numbers of Nestin-, Vimentin-, and Nestin/Vimentin-positive cells in neurogenic niches and the olfactory bulb. These changes were accompanied by an increased number of BrdU-positive cells in the hippocampus and SVZ. The latter changes were strongly correlated with changes in the numbers of VEGF- and VEGF/Sox14-positive cells. The morphological changes were characterized by significant neural loss, a characteristic shift in entorhinal cortex–hippocampus circuit activity, and decreased spontaneous alternation in a behavioral test. We conclude that although an injection of Aβ (1-42) induced stem cell proliferation and triggered neurogenesis at a certain stage, this process was incomplete and led to neural stem cell immaturity. We propose the idea of enhancing adult neurogenesis as a promising strategy for preventing dementia at healthy elderly people andpeople at high risk for developing AD, or treating patients diagnosed with AD.     

Pour-point depressing and thickening properties of polymethacrylate additives

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 9, pp. 33–34, September, 1990.