1,286 research outputs found
Structural Game Characteristics and Problematic Gaming:Introduction of the Risk Characteristics Checklist for Games (RCCG)
Introduction: The current state of research suggests that personal, environmental, and product-related risk factors contribute to the development and maintenance of gaming disorder. Concerning game related risk factors, evidence points to certain game features contributing to the overall risk of gaming disorder, as for example reward features, social features, and monetization features. However, no standardized instrument is available to capture risk enhancing game characteristics. Methods: Based on theoretical considerations and stepwise conducted qualitative analyses of in-game content, risk-enhancing game features were identified and specified. Furthermore, a pilot study was conducted comprising N = 4,468 students (M[Age] = 14.54 years, SD = 1.37 years). Game features of the preferred games of the students were analyzed regarding their predictive value of gaming disorder. Results: Data suggests that two features are associated most strongly with gaming disorder: 1) mandatory social interactions (β = .20), and 2) number of reward categories (β = .12). Based on these findings and further updates, the RCCG was refined and finalized. Conclusions: With the RCCG, a structured instrument to capture, describe, and evaluate risk enhancing structural characteristics of video games is available. The RCCG enables a general risk assessment of games as well as recommended age-classifications based on certain structural features unsuitable for specific age groups
Coframe teleparallel models of gravity. Exact solutions
The superstring and superbrane theories which include gravity as a necessary
and fundamental part renew an interest to alternative representations of
general relativity as well as the alternative models of gravity. We study the
coframe teleparallel theory of gravity with a most general quadratic
Lagrangian. The coframe field on a differentiable manifold is a basic dynamical
variable. A metric tensor as well as a metric compatible connection is
generated by a coframe in a unique manner. The Lagrangian is a general linear
combination of Weitzenb\"{o}ck's quadratic invariants with free dimensionless
parameters \r_1,\r_2,\r_3.
Every independent term of the Lagrangian is a global SO(1,3)-invariant
4-form. For a special choice of parameters which confirms with the local
SO(1,3) invariance this theory gives an alternative description of Einsteinian
gravity - teleparallel equivalent of GR.
We prove that the sign of the scalar curvature of a metric generated by a
static spherical-symmetric solution depends only on a relation between the free
parameters. The scalar curvature vanishes only for a subclass of models with
\r_1=0. This subclass includes the teleparallel equivalent of GR. We obtain
the explicit form of all spherically symmetric static solutions of the
``diagonal'' type to the field equations for an arbitrary choice of free
parameters. We prove that the unique asymptotic-flat solution with Newtonian
limit is the Schwarzschild solution that holds for a subclass of teleparallel
models with \r_1=0. Thus the Yang-Mills-type term of the general quadratic
coframe Lagrangian should be rejected.Comment: 28 pages, Latex error is fixe
Psychologische Prädiktoren für das Auftreten einer Major Depression und einer PTBS nach schweren Unfällen
Theoretischer Hintergrund/Fragestellung: Ziel unserer prospektiven Studie war die Identifikation von Prädiktoren für das Auftreten einer Depression im ersten halben Jahr nach einem Unfall.
Methode: Es wurden 52 Unfallpatienten untersucht. Die Ersterhebung erfolgte innerhalb der ersten sechs Wochen nach dem Unfall.
Ergebnisse: Depressive Patienten gaben kurz nach dem Unfall eine geringere Lebenszufriedenheit und soziale Unterstützung an und berichteten häufiger über psychische Störungen und traumatische Erlebnisse vor dem Unfall als Nicht-Depressive. Außerdem litten sie zum Zeitpunkt der Ersterhebung häufiger unter psychischen Störungen und fühlten sich durch die psychischen Symptome stärker beeinträchtigt.
Schlussfolgerung: Die Ergebnisse legen nahe, dass Patienten mit einem Risiko für die Entwicklung einer Depression bereits kurz nach einem Unfall identifiziert werden können
Synthesis and Magnetic Characterization of Metal-filled Double-sided Porous Silicon Samples
A magnetic semiconductor/metal nanocomposite with a nanostructured silicon wafer as base material and incorporated metallic nanostructures (Ni, Co, NiCo) is fabricated in two electrochemical steps. First, the silicon template is anodized in an HF-electrolyte to obtain a porous structure with oriented pores grown perpendicular to the surface. This etching procedure is carried out either in forming a sample with a single porous layer on one side or in producing a double-sided specimen with a porous layer on each side. Second, this matrix is used for deposition of transition metals as Ni, Co or an alloy of these. The achieved hybrid material with incorporated Ni- and Co-nanostructures within one sample is investigated magnetically. The obtained results are compared with the ones gained from samples containing a single metal
Axial Torsion-Dirac spin Effect in Rotating Frame with Relativistic Factor
In the framework of spacetime with torsion and without curvature, the Dirac
particle spin precession in the rotational system is studied. We write out the
equivalent tetrad of rotating frame, in the polar coordinate system, through
considering the relativistic factor, and the resultant equivalent metric is a
flat Minkowski one. The obtained rotation-spin coupling formula can be applied
to the high speed rotating case, which is consistent with the expectation.Comment: 6 page
Compaction and dilation rate dependence of stresses in gas-fluidized beds
A particle dynamics-based hybrid model, consisting of monodisperse spherical
solid particles and volume-averaged gas hydrodynamics, is used to study
traveling planar waves (one-dimensional traveling waves) of voids formed in
gas-fluidized beds of narrow cross sectional areas. Through ensemble-averaging
in a co-traveling frame, we compute solid phase continuum variables (local
volume fraction, average velocity, stress tensor, and granular temperature)
across the waves, and examine the relations among them. We probe the
consistency between such computationally obtained relations and constitutive
models in the kinetic theory for granular materials which are widely used in
the two-fluid modeling approach to fluidized beds. We demonstrate that solid
phase continuum variables exhibit appreciable ``path dependence'', which is not
captured by the commonly used kinetic theory-based models. We show that this
path dependence is associated with the large rates of dilation and compaction
that occur in the wave. We also examine the relations among solid phase
continuum variables in beds of cohesive particles, which yield the same path
dependence. Our results both for beds of cohesive and non-cohesive particles
suggest that path-dependent constitutive models need to be developed.Comment: accepted for publication in Physics of Fluids (Burnett-order effect
analysis added
Injeção intracitoplasmatica de células espermáticas e suas aplicações na reprodução dos bovinos.
bitstream/CENARGEN/23223/1/doc084.pd
Motor Sequence Learning Deficits in Idiopathic Parkinson’s Disease Are Associated With Increased Substantia Nigra Activity
Previous studies have shown that persons with Parkinson’s disease (pwPD) share
specific deficits in learning new sequential movements, but the neural substrates of
this impairment remain unclear. In addition, the degree to which striatal dopaminergic
denervation in PD affects the cortico-striato-thalamo-cerebellar motor learning network
remains unknown. We aimed to answer these questions using fMRI in 16 pwPD and 16
healthy age-matched control subjects while they performed an implicit motor sequence
learning task. While learning was absent in both pwPD and controls assessed with
reaction time differences between sequential and random trials, larger error-rates during
the latter suggest that at least some of the complex sequence was encoded. Moreover,
we found that while healthy controls could improve general task performance indexed
by decreased reaction times across both sequence and random blocks, pwPD could
not, suggesting disease-specific deficits in learning of stimulus-response associations.
Using fMRI, we found that this effect in pwPD was correlated with decreased activity
in the hippocampus over time. Importantly, activity in the substantia nigra (SN) and
adjacent bilateral midbrain was specifically increased during sequence learning in
pwPD compared to healthy controls, and significantly correlated with sequence-specific
learning deficits. As increased SN activity was also associated (on trend) with higher
doses of dopaminergic medication as well as disease duration, the results suggest that
learning deficits in PD are associated with disease progression, indexing an increased
drive to recruit dopaminergic neurons in the SN, however, unsuccessfully. Finally, there
were no differences between pwPD and controls in task modulation of the cortico-striato-thalamo-cerebellar network. However, a restricted nigral-striatal model showed
that negative modulation of SN to putamen connection was larger in pwPD compared
to controls during random trials, while no differences between the groups were found
during sequence learning. We speculate that learning-specific SN recruitment leads to a
relative increase in SN- > putamen connectivity, which returns to a pathological reduced
state when no learning takes plac
Axial-Vector Torsion and the Teleparallel Kerr Spacetime
In the context of the teleparallel equivalent of general relativity, we
obtain the tetrad and the torsion fields of the stationary axisymmetric Kerr
spacetime. It is shown that, in the slow rotation and weak field
approximations, the axial-vector torsion plays the role of the gravitomagnetic
component of the gravitational field, and is thus the responsible for the
Lense-Thirring effect.Comment: 9 pages, no figures, to appear in Class. Quant. Gra
Quadro citológico vaginal, concentração plasmática de progesterona durante a gestação e medidas fetais em paca (Cuniculus paca Linnaeus, 1766).
Em 27 pacas (Cuniculus paca Linnaeus, 1766) objetivou-se descrever aos 30, 60 e 90 dias (D) de prenhez diagnosticada por ultrassonografia (US), os tipos celulares do epitélio vaginal em esfregaços vaginais, relatar as condições de abertura da vulva e as características do muco vaginal, determinar a concentração plasmática de progesterona (P4) por radioimunoensaio, e ainda, mensurar por ultrassonografia (US) o diâmetro biparietal (DBP) fetal aos 60 e 90 dias de prenhez. No D30, 40% das amostras exibiram células (com características estrogênicas) superficiais e presença de núcleos nus. Nos D60 e D90, células parabasais, intermediárias, superficiais e naviculares estavam presentes nas mesmas proporções, mas células endocervicais foram descritas em apenas 73,9% e 69% das amostras daqueles dias, respectivamente. No D30 a maior proporção de células naviculares e superficiais diferiu (p < 0,05) em relação aos outros tipos celulares presentes. O muco vaginal apresentou-se cristalino e fluido em 100% e em 70% das fêmeas nos D30 e D60, respectivamente. Observou-se o vestíbulo vaginal aberto em torno de 50% das fêmeas em todos os dias de exames. Valores mínimos detectáveis de P4 foram obtidos em 72% e em 83% das fêmeas, enquanto que as médias das medidas dos DBP foram 1,25 cm (± 0,16) e 2,34 cm (± 0,25) nos D60 e D90, respectivamente. O quadro citológico vaginal nos D30, D60 e D90 e o DBP fornecem elementos que contribuem para diagnóstico de gestação em pacas. A concentração de P4 demonstra a necessidade de maiores estudos da endocrinologia da gestação em pacas
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