418 research outputs found
A longitudinal study of adolescent Internet addiction: the role of conscientiousness and classroom hostility
Over the last decade, research on Internet Addiction (IA) has increased. However, almost all studies in this area are cross-sectional and do not examine the context in which internet use takes place. Therefore, a longitudinal study examined the role of conscientiousness (as a personality trait) and classroom hostility (as a contextual factor) in the development of IA. The participants comprised 648 adolescents and were assessed over a two-year period (while aged 16–18 years). A three-level hierarchical linear model was carried out on the data collected. Findings revealed that: (i) lower conscientiousness was associated with IA and this did not change over time; and (ii) although being in a more hostile classroom did not initially have a significant effect, it increased girls’ IA vulnerability over time and functioned protectively for boys. Results indicated that the contribution of individual and contextual IA factors may differ across genders and over time. More specifically, although the protective effect of conscientiousness appeared to hold, the over-time effect of classroom hostility increased the risk of IA for girls. These findings are discussed in relation to the psychological literature. The study’s limitations and implications are also discussed
Vasospastic Phenomena on the Luminal Replica of Rat Brain Vessels
Strikingly localized ring-like constrictions (other than sphincters, cushions and offshoot furrows) have appeared on the casted vessels of some of our preparations. Morphology of the phenomena reveals diverse degree of active contraction of the vessel wall, ranging from corrugation of the luminal surface to near severance of the acrylic cast. Distribution of the vasospastic phenomena reveals as particularly affected the arteries in the diameter range between 25 and 75 μm, that belong either to intra-arterial anastomoses between the branches of each of the three major cerebral arteries or to their terminal junctions in the border zones (inter-arterial anastomoses). Among the possible causes for the occurrence of the observed vasospasms, we indicate the susceptibility to raised intraluminal pressure during injection, producing contraction of the smooth muscle cell. Reactivity appears heightened in the anastomotic districts of the circulation. The evidence of so-called plastic strips clinging to constricted sections of affected vessels prompts re-examination of their proposed origin as plastic wrapping . Rather, they appear to be remnants of dynamic elements of the vascular wall (smooth muscle cells) that resisted corrosion
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Risks and opportunities for youth in the digital era: a cyber-developmental approach to mental health
Due to continued groundbreaking digital advancements, Internet use has increased significantly. This has led to a heated debate in relation to weighing the many advantages of the technology against its potentially deleterious effects. To address such questions, experts converge on the need for greater knowledge around the way individual differences, partly shaped by an individual’s unique experiences of engaging with the medium, and partly by other real-life experiences, lead to different developmental trajectories. Consequently, the goals of the present review are to (i) broadly describe differences in digital media applications, users, and usage; (ii) introduce the Cyber-Developmental Framework (CDF), as an overarching framework for understanding individual differences in adaptive and maladaptive digital media use among youth; (iii) delineate the cyber-component of this framework in relation to users’ experience of the digital context, their activity within it, as well as their digital self-presence, which may have an impact on their digital media use; and (iv) summarize priorities and future directions through the lens of this CDF. Within this context, this review particularly emphasizes the effect of digital media use on youth’s psychological well-being. It is argued that the trajectory youth will follow in their use of the Internet is a function of the interplay between their characteristics, their proximate and distal contexts, and the particular features of the digital application(s) that the individual is engaged in. The review points to the need to conduct research focusing on better understanding the developmental and digital-context-related influences on youth’s trajectories of Internet use
The Capillary Bed in the Choroid Plexus of the Lateral Ventricles: A Study of Luminal Casts
Micro-angioarchitecture of the choroid plexus of the lateral ventricles is investigated in microcorrosion casts of animal and human preparations studied with the scanning electron microscope. The capillary bed in the diverse regions of the tissue belongs to one of three patterns: (1)-a network of capillary meshes that envelop the larger arteries and veins predominates in the central segment. (2)-in the villous regions a leaf-like organization of sinusoids is found together with (3)-fronds of glomerular formations. Glomeruli are formed when arterial afferents and venous efferents converge in a quasi hilar structure before branching in arterio-venous loops. Nodular thickenings are observed on glomerular capillaries The preparations studied (rat, dog, human) are remarkably similar and differ mostly in degree of occurrence of common architectural patterns. Arterio-venous communications are found at the hilus of human glomerular formations
Using bacterial extract along with differential gene expression in Acropora millepora Larvae to decouple the processes of attachment and metamorphosis
Biofilms of the bacterium Pseudoalteromonas induce metamorphosis of acroporid coral larvae. The bacterial metabolite tetrabromopyrrole (TBP), isolated from an extract of Pseudoalteromonas sp. associated with the crustose coralline alga (CCA) Neogoniolithon fosliei, induced coral larval metamorphosis (100%) with little or no attachment (0-2%). To better understand the molecular events and mechanisms underpinning the induction of Acropora millepora larval metamorphosis, including cell proliferation, apoptosis, differentiation, migration, adhesion and biomineralisation, two novel coral gene expression assays were implemented. These involved the use of reverse-transcriptase quantitative PCR (RT-qPCR) and employed 47 genes of interest (GOI), selected based on putative roles in the processes of settlement and metamorphosis. Substantial differences in transcriptomic responses of GOI were detected following incubation of A. millepora larvae with a threshold concentration and 10-fold elevated concentration of TBP-containing extracts of Pseudoalteromonas sp. The notable and relatively abrupt changes of the larval body structure during metamorphosis correlated, at the molecular level, with significant differences (p<0.05) in gene expression profiles of 24 GOI, 12 hours post exposure. Fourteen of those GOI also presented differences in expression (p<0.05) following exposure to the threshold concentration of bacterial TBP-containing extract. The specificity of the bacterial TBP-containing extract to induce the metamorphic stage in A. millepora larvae without attachment, using a robust, low cost, accurate, ecologically relevant and highly reproducible RT-qPCR assay, allowed partially decoupling of the transcriptomic processes of attachment and metamorphosis. The bacterial TBP-containing extract provided a unique opportunity to monitor the regulation of genes exclusively involved in the process of metamorphosis, contrasting previous gene expression studies that utilized cues, such as crustose coralline algae, biofilms or with GLW-amide neuropeptides that stimulate the entire onset of larval metamorphosis and attachment. © 2012 Siboni et al
New nickel(II) and iron(II) helicates and tetrahedra derived from expanded quaterpyridines
As an extension of prior studies involving the linear quaterpyridine ligand, 5,5'''-dimethyl-2,2':5',5'':2'',2'''-quaterpyridine 1, the synthesis of the related expanded quaterpyridine derivatives 2 and 3 incorporating dimethoxy-substituted 1,4-phenylene and tetramethoxy-substituted 4,4'-biphenylene bridges between pairs of 2,2'-bipyridyl groups has been carried out via double-Suzuki coupling reactions between 5-bromo-5'-methyl-2'-bipyridine and the appropriate di-pinacol-diboronic esters using microwave heating. Reaction of 2 and 3 with selected Fe(II) or Ni(II) salts yields a mixture of both [M2L3]4+ triple helicates and [M4L6]8+ tetrahedra, in particular cases the ratio of the products formed was shown to be dependent on the reaction conditions; the respective products are all sufficiently inert to allow their chromatographic separation and isolation. Longer reaction times and higher concentrations were found to favour tetrahedron formation. The X-ray structures of solvated [Ni2(2)3](PF6)4, [(PF6) ⊂ Fe4(2)6](PF6)7, [Fe4(3)6](PF6)8 and [Ni4(3)6](PF6)8 have been determined, while the structure of the parent Fe(II) cage in the series, [(PF6) ⊂ Fe4(1)6](PF6)7, was reported previously. The internal volumes of the Fe(II) tetrahedral cages have been calculated and increase from 102 Å3 for [Fe4(1)6]8+ to 227 Å3 for [Fe4(2)6]8+ to 417 Å3 for [Fe4(3)6]8+ and to an impressive 839 Å3 for [Ni4(3)6]8+. The corresponding void volume in the triple helicate [Ni2(2)3]4+ is 29 Å3
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Draconian policy measures are unlikely to prevent disordered gaming
In August of 2021, China imposed severe restrictions on children’s online gaming time. We argue that such a policy may seem useful on the surface but does not reflect the current evidence concerning prevention of disordered gaming. Videogame play is normal for children worldwide, and like other leisure activities can lead to benefits for the majority and problems for a minority. Problematic or disordered play results from the interaction of multiple risk factors that are not addressed by draconian policy measures. Identifying these factors through stakeholder-engaged research and current evidence will be much more likely to succeed in preventing disordered gaming and promoting youth wellbeing
An integrated ultra-high vacuum apparatus for growth and in situ characterization of complex materials
Here we present an integrated ultra-high vacuum apparatus \u2013 named MBE-Cluster \u2013 dedicated to the growth
and in situ structural, spectroscopic and magnetic characterization of complex materials. Molecular Beam
Epitaxy (MBE) growth of metal oxides, e.g. manganites, and deposition of patterned metallic layers can be
fabricated and in situ characterized by reflection high-energy electron diffraction (RHEED), low-energy
electron diffraction (LEED) - Auger Electron Spectroscopy, X-ray photoemission spectroscopy (PES) and
azimuthal longitudinal magneto-optic Kerr effect (MOKE). The temperature can be controlled in the range
from 5 to 580 K, with the possibility of application of magnetic fields H up to \ub17 kOe and electric fields E for
voltages up to \ub1500 V. The MBE-Cluster operates for in-house research as well as user facility in combination
with the APE beamlines at Sincrotrone-Trieste and the high harmonic generator (HHG) facility for timeresolved
spectroscopy
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