12,671 research outputs found
On --domains and star operations
Let be a star operation on an integral domain . Let \f(D) be the
set of all nonzero finitely generated fractional ideals of . Call a
--Pr\"ufer (respectively, --Pr\"ufer) domain if
(respectively, ) for all F\in
\f(D). We establish that --Pr\"ufer domains (and --Pr\"ufer
domains) for various star operations span a major portion of the known
generalizations of Pr\"{u}fer domains inside the class of --domains. We also
use Theorem 6.6 of the Larsen and McCarthy book [Multiplicative Theory of
Ideals, Academic Press, New York--London, 1971], which gives several equivalent
conditions for an integral domain to be a Pr\"ufer domain, as a model, and we
show which statements of that theorem on Pr\"ufer domains can be generalized in
a natural way and proved for --Pr\"ufer domains, and which cannot be. We
also show that in a --Pr\"ufer domain, each pair of -invertible
-ideals admits a GCD in the set of -invertible -ideals,
obtaining a remarkable generalization of a property holding for the "classical"
class of Pr\"ufer --multiplication domains. We also link being --Pr\"ufer (or --Pr\"ufer) with the group Inv of -invertible -ideals (under -multiplication) being
lattice-ordered
An exploratory study on internet addiction, somatic symptoms and emotional and behavioral functioning in school-aged adolescents
Objective: In the last two decades there has been a significant transformation regarding the use of new technologies. Despite growing acknowledgement concerning the different activities and functions of digital technologies, there remains a lack of understanding on how technology overuse may negatively impact both physical and psychosocial well-being. Although researchers have begun to explore the meaning and implications of excessive Internet use in non-clinical populations of children and adolescents, there is still little consistent knowledge on the topic. This study aimed to extend existing knowledge on the excessive use of the Internet among school-aged adolescents, focusing on its association with recurrent somatic symptoms, depressive risk and behavioral and emotional problems. Method: Two hundred and forty adolescents (51.9% females) aged between 10 and 15, participated in this study. Data was collected using the Children’s Somatization Inventory, the Internet Addiction Test, the Children’s Depression Inventory, the Youth Self Report and the Emotion Regulation Questionnaire. Structural Equation Model analysis was used to analyse the data. Results: Approximately 21.8% of participants reported excessive Internet use based on Young’s criteria. Higher levels of Internet use were associated with somatic and depressive symptoms as well as emotional and behavioral problems. Depressive Symptoms predicted both Internet Addiction (b = 0.304, p < 0.001) and Internalizing (b = 0.542, p <0.001) and Externalizing problems (b = 0.484, p < 0.001). Internet Addiction also significantly predicted both Internalizing (b = 0.162, p = 0.02) and Externalizing problems (b = 0.183, p = 0.02). Finally, Structural Equation Modeling showed that the indirect effect of Depressive Symptoms (via Internet Addiction) on Internalizing or Externalizing problems were significant. Conclusions: Longitudinal studies are needed to confirm these findings and to identify the mechanisms linking Internet use, somatic symptoms and adaptive functioning
Digital electric field induced switching of plasmonic nanorods using an electro-optic fluid fiber
We demonstrate the digital electric field induced switching of plasmonic
nanorods between 1 and 0 orthogonal aligned states using an electro-optic fluid
fiber component. We show by digitally switching the nanorods, that thermal
rotational diffusion of the nanorods can be circumvented, demonstrating an
approach to achieve submicrosecond switching times. We also show, from an
initial unaligned state, that the nanorods can be aligned into the applied
electric field direction in 110 nanoseconds. The high-speed digital switching
of plasmonic nanorods integrated into an all-fiber optical component may
provide novel opportunities for remote sensing and signaling applications
A Multistage Method for SCMA Codebook Design Based on MDS Codes
Sparse Code Multiple Access (SCMA) has been recently proposed for the future
generation of wireless communication standards. SCMA system design involves
specifying several parameters. In order to simplify the procedure, most works
consider a multistage design approach. Two main stages are usually emphasized
in these methods: sparse signatures design (equivalently, resource allocation)
and codebook design. In this paper, we present a novel SCMA codebook design
method. The proposed method considers SCMA codebooks structured with an
underlying vector space obtained from classical block codes. In particular,
when using maximum distance separable (MDS) codes, our proposed design provides
maximum signal-space diversity with a relatively small alphabet. The use of
small alphabets also helps to maintain desired properties in the codebooks,
such as low peak-to-average power ratio and low-complexity detection.Comment: Submitted to IEEE Wireless Communication Letter
Newton-Raphson Solution of Nonlinear Delay-Free Loop Filter Networks
For their numerical properties and speed of convergence, Newton-Raphson methods are frequently used to compute nonlinear audio electronic circuit models in the digital domain. These methods are traditionally employed regardless of preliminary considerations about their applicability, primarily because of a lack of flexible mathematical tools making the convergence analysis an easy task. We define the basin delimiter, a tool that can be applied to the case when the nonlinear circuit is modeled by a delay-free loop network. This tool is derived from a known convergence theorem providing a sufficient condition for quadratic speed of convergence of the method. After substituting the nonlinear characteristics with equivalent linear filters that compute Newton-Raphson on the existing network, through the basin delimiter, we figure out constraints guaranteeing quadratic convergence speed in the diode clipper. Further application to a ring modulator circuit does not lead to comparably useful constraints for quadratic convergence; however, also in this circuit, the basin delimiter has a magnitude roughly proportional to the number of iterations needed by the solver to find a solution. Together, such case studies foster refinement and generalization of this tool as a speed predictor, with potential application to the design of virtual analogue systems for real-time digital audio effects
Ergodicity breaking in strong and network-forming glassy system
The temperature dependence of the non-ergodicity factor of vitreous GeO,
, as deduced from elastic and quasi-elastic neutron scattering
experiments, is analyzed. The data are collected in a wide range of
temperatures from the glassy phase, up to the glass transition temperature, and
well above into the undercooled liquid state. Notwithstanding the investigated
system is classified as prototype of strong glass, it is found that the
temperature- and the -behavior of follow some of the predictions
of Mode Coupling Theory. The experimental data support the hypothesis of the
existence of an ergodic to non-ergodic transition occurring also in network
forming glassy systems
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