553 research outputs found
Point-to-Multipoint Communication Enablers for the Fifth Generation of Wireless Systems
(c) 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.[EN] 3GPP has enhanced the point-to-multipoint
(PTM) communication capabilities of 4G LTE in all
releases since the adoption of eMBMS in Release-9.
Recent enhancements cover not only television services, but also critical machine-type and vehicular
communications, following the backward-compatibility design philosophy of LTE. This article discusses
the opportunity in the design and standardization
of 5G to break with the existing paradigm for PTM
transmissions in 4G LTE, where broadcast PTM
transmissions were initially conceived as an add-on
and pre-positioned service. 5G brings the opportunity to incorporate PTM capabilities as built-in delivery
features from the outset, integrating point-to-point
and PTM modes under one common framework
and enabling dynamic use of PTM to maximize network and spectrum efficiency. This approach will
open the door to completely new levels of network
management and delivery cost efficiency. The article
also discusses the implications of PTM for network
slicing to customize and optimize network resources
on a common 5G infrastructure to accommodate
different use cases and services taking into account
user densityThis work was supported in part by the European Commission under the 5G-PPP project Broadcast and Multicast Communication Enablers for the Fifth-(H2020-ICT-2016-2 call, grant number 761498).
The views expressed in this contribution are those
of the authors and do not necessarily represent
the project.Generation of Wireless Systems 5G-XcastGomez-Barquero, D.; Navratil, D.; Appleby, S.; Stagg, M. (2018). Point-to-Multipoint Communication Enablers for the Fifth Generation of Wireless Systems. IEEE Communications Standards Magazine. 2(1):53-59. https://doi.org/10.1109/MCOMSTD.2018.170006953592
The general harmonic-oscillator brackets: compact expression, symmetries, sums and Fortran code
We present a very simple expression and a Fortran code for the fast and
precise calculation of three-dimensional harmonic-oscillator transformation
brackets. The complete system of symmetries for the brackets along with
analytical expressions for sums, containing products of two and three brackets,
is given.Comment: 13 pages, accepted for publication in Nuclear Physics
Discrepancy between experimental and theoretical -decay rates resolved from first principles
-decay, a process that changes a neutron into a proton (and vice
versa), is the dominant decay mode of atomic nuclei. This decay offers a unique
window to physics beyond the standard model, and is at the heart of
microphysical processes in stellar explosions and the synthesis of the elements
in the Universe. For 50 years, a central puzzle has been that observed
-decay rates are systematically smaller than theoretical predictions.
This was attributed to an apparent quenching of the fundamental coupling
constant 1.27 in the nucleus by a factor of about 0.75 compared
to the -decay of a free neutron. The origin of this quenching is
controversial and has so far eluded a first-principles theoretical
understanding. Here we address this puzzle and show that this quenching arises
to a large extent from the coupling of the weak force to two nucleons as well
as from strong correlations in the nucleus. We present state-of-the-art
computations of -decays from light to heavy nuclei. Our results are
consistent with experimental data, including the pioneering measurement for
Sn. These theoretical advances are enabled by systematic effective
field theories of the strong and weak interactions combined with powerful
quantum many-body techniques. This work paves the way for systematic
theoretical predictions for fundamental physics problems. These include the
synthesis of heavy elements in neutron star mergers and the search for
neutrino-less double--decay, where an analogous quenching puzzle is a
major source of uncertainty in extracting the neutrino mass scale.Comment: 20 pages, 18 figure
Beyond the Shell Model: The Canonical Nuclear Many-Body Problem as an Effective Theory
We describe a strategy for attacking the canonical nuclear structure problem
---bound-state properties of a system of point nucleons interacting via a
two-body potential---which involves an expansion in the number of particles
scattering at high momenta, but is otherwise exact. The required
self-consistent solutions of the Bloch-Horowitz equation for effective
interactions and operators are obtained by an efficient Green's function method
based on the Lanczos algorithm. We carry out this program for the simplest
nuclei, d and He, to contrast a rigorous effective theory with the shell
model, thereby illustrating several of the uncontrolled approximations in the
latter.Comment: Revtex; two columns; four pages; two figures; submitted to Phys. Rev.
Let
The Shell Model, the Renormalization Group and the Two-Body Interaction
The no-core shell model and the effective interaction can
both be derived using the Lee-Suzuki projection operator formalism. The main
difference between the two is the choice of basis states that define the model
space. The effective interaction can also be derived using
the renormalization group. That renormalization group derivation can be
extended in a straight forward manner to also include the no-core shell model.
In the nuclear matter limit the no-core shell model effective interaction in
the two-body approximation reduces identically to . The same
considerations apply to the Bloch-Horowitz version of the shell model and the
renormalization group treatment of two-body scattering by Birse, McGovern and
Richardson
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2-Oxoesters: A Novel Class of Potent and Selective Inhibitors of Cytosolic Group IVA Phospholipase A2.
Cytosolic phospholipase A2 (GIVA cPLA2) is the only PLA2 that exhibits a marked preference for hydrolysis of arachidonic acid containing phospholipid substrates releasing free arachidonic acid and lysophospholipids and giving rise to the generation of diverse lipid mediators involved in inflammatory conditions. Thus, the development of potent and selective GIVA cPLA2 inhibitors is of great importance. We have developed a novel class of such inhibitors based on the 2-oxoester functionality. This functionality in combination with a long aliphatic chain or a chain carrying an appropriate aromatic system, such as the biphenyl system, and a free carboxyl group leads to highly potent and selective GIVA cPLA2 inhibitors (X I(50) values 0.00007-0.00008) and docking studies aid in understanding this selectivity. A methyl 2-oxoester, with a short chain carrying a naphthalene ring, was found to preferentially inhibit the other major intracellular PLA2, the calcium-independent PLA2. In RAW264.7 macrophages, treatment with the most potent 2-oxoester GIVA cPLA2 inhibitor resulted in over 50% decrease in KLA-elicited prostaglandin D2 production. The novel, highly potent and selective GIVA cPLA2 inhibitors provide excellent tools for the study of the role of the enzyme and could contribute to the development of novel therapeutic agents for the treatment of inflammatory diseases
Why the cells look like that - the influence of learning with emotional design and elaborative interrogations
We investigated emotional design features that may influence multimedia learning with a self-generated learning (SGL) activity, namely answering elaborative interrogations. We assumed that a positive emotional design would be associated with a higher motivation to accomplish the additional SGL activity. Moreover, an interaction was expected: Learners learning with a positive emotional design should profit from learning with elaborative interrogations whereas learners learning with a negative emotional design would not profit from this strategy to the same extent but would rather benefit through reading. Since no negative emotional design existed yet, we additionally took the challenge to construct one. In a preliminary study, the emotional design features were pre-tested for their influence on emotional state and according to evaluation results, emotional design features were modified for the final versions. For the main study, German students (N = 228) were randomly assigned to one of six conditions that resulted from a 3 × 2 Design with emotional design (intended-positive vs. intended-neutral vs. intended-negative) and SGL activity (elaborative interrogations vs. no elaborative interrogations). Contrary to expectations, the intended-negative design worked not out as intended, but was rather comparable with the positive emotional design with respect to learners’ emotional states. Learner motivation was higher when learning with the intended-negative emotional than the neutral design. The quality of the elaborated answers and learner motivation correlated positively with the performance of all learning outcome scores. For transfer questions which addressed the elaborated concepts, an interaction can be reported: learners learning with the positive emotional design benefitted from learning by reading compared to answering the elaborative interrogations. Regarding transfer questions whose concepts were explicitly described in the instructional material, it was better to learn with the intended-negative emotional than the neutral design. According to results of mediation analyses, the influence of motivation on learning outcomes could mostly be explained by the influence of motivation on answering the elaborative interrogations. Implications for creating emotional design as well as its effect on learning are discussed
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