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Quantum gravity wormholes and topological teleporter

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arXiv 2019年

作者： Nikitin, Igor Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53757 Germany

The question of a possibility of opening a wormhole due to the deformation of the equation of state of the matter caused by quantum gravity effects is considered. As a wormhole environment, the previously considered model of a galaxy with radial flows of dark matter is selected. The calculation shows, that for a wormhole solution in the framework of this model, after the nominal classical density exceeds a critical value in the Planck range, the components of the energy-momentum tensor become negative in a certain order. First, the mass density becomes negative, then the radial pressure, then the tangential pressure. In this case, at some point the flare-out conditions necessary and sufficient to open the wormhole are fulfilled. Calculations are made to open a wormhole in a model with parameters of the Milky Way galaxy. It is shown that the opening of the wormhole is accompanied by a separation of the bubble of space, completely detached from the wormhole and the outer space. In addition to this solution, a topologically dual one is found, looking like an instant swapping of two volumes in space, which can be interpreted as an event of teleportation. Copyright © 2019, The Authors. All rights reserved.

关键词： Galaxies

New dark matter scenarios with low energy photons and neutrinos

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arXiv 2023年

作者： Nikitin, Igor Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53757 Germany

In this paper, a cosmological model is considered, in which dark matter is emitted by T-symmetric quasi-black holes distributed over galaxies. Low energy photons and neutrinos are taken as candidates for dark matter particles. Photon case can be closed due to the suppression of electromagnetic waves by interstellar/intergalactic medium. For neutrinos, two scenarios are considered. In the first, light neutrinos pair to bosonic quasiparticles that form massive halos around galaxies. In the second, heavier sterile neutrinos form massive halos without pairing. At the observables level, both scenarios turn out to be equivalent to the standard LambdaCDM model. At the same time, the considered model possesses additional sources – quasi-black holes – that can produce the required number of neutrinos in addition to the Big Bang. This opens up additional possibilities for cosmological constructions. The matching of the model with early cosmology and ongoing neutrino experiments is discussed. In addition, the possibility of solving general cosmological problems, including horizon, flatness and cosmological constant problems, as well as Hubble tension, within the framework of the considered model, is discussed. © 2023, CC BY.

关键词： Photons

Identifying gene-specific variations in biomedical text

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Journal of Bioinformatics and Computational Biology 2007年第6期5卷 1277-1296页

作者： Klinger, Roman Friedrich, Christoph M. Mevissen, Heinz Theodor Fluck, Juliane Hofmann-apitius, Martin Furlong, Laura I. Sanz, Ferran Department of Bioinformatics Fraunhofer Institute for Algorithms and Scientific Computing 53754 Sankt Augustin Schloss Birlinghoven Germany Research Unit on Biomedical Informatics (GRIB) IMIM UPF PRBB E-08003 Barcelona c/ Dr. Aiguader 88 Spain

The influence of genetic variations on diseases or cellular processes is the main focus of many investigations, and results of biomedical studies are often only accessible through scientific publications. Automatic extraction of this information requires recognition of the gene names and the accompanying allelic variant information. In a previous work, the OSIRIS system for the detection of allelic variation in text based on a query expansion approach was communicated. Challenges associated with this system are the relatively low recall for variation mentions and gene name recognition. To tackle this challenge, we integrate the ProMiner system developed for the recognition and normalization of gene and protein names with a conditional random field (CRF)-based recognition of variation terms in biomedical text. Following the newly developed normalization of variation entities, we can link textual entities to Single Nucleotide Polymorphism database (dbSNP) entries. The performance of this novel approach is evaluated, and improved results in comparison to state-of-the-art systems are reported. © 2007 Imperial College Press.

关键词： Conditional random field Named entity recognition Normalization Single nucleotide polymorphism SNP Variants

RDM-stars and galactic rotation curves

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arXiv 2019年

作者： Nikitin, Igor Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53757 Germany

The recently formulated model of black holes coupled to the radial flows of dark matter (RDM-stars) is considered and the shape of the galactic rotation curves predicted by the model is evaluated. Under the assumption that the density of black holes is proportional to the density of luminous matter, the model perfectly fits the experimental data, both for the universal rotation curve, describing the spiral galaxies of a general form, and for the grand rotation curve, describing the orbital velocities of Milky Way galaxy in a wide range of distances. The modeling of the galactic gravitational field at large distances from the center and out of the galactic plane is also discussed. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

Galactic model with a phase transition from dark matter to dark energy

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arXiv 2021年

作者： Nikitin, Igor Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53757 Germany

This work continues the construction of a recently proposed model of dark matter stars. In this model, dark matter quanta are sterile massless particles that are emitted from the central regions of the galaxy in the radial direction. As a result, at large distances r from the center of the galaxy, the mass density of dark matter has the form ρ ∼ r−2, in contrast to the homogeneous model ρ = Const. In the cosmological context, the homogeneous model with massless particles corresponds to the radiation epoch of the expansion of the universe, while the proposed inhomogeneous model turns out to be equivalent to ΛCDM. In this paper, scenarios will be considered in which the radial emission of dark matter is brought into hydrostatic equilibrium with a uniform background. It is shown that solutions exist if the uniform background has an equation of state typical for dark energy. Thus, this model describes a phase transition from dark matter inside the galaxy to dark energy outside of it. The specific mechanism for such a transition could be Bose-Einstein condensation. In addition, the question of what happens if dark matter particles are not sterile, for example, are photons of the Standard Model, is considered. © 2021, CC BY.

关键词： Galaxies

Optimization of retrieval algorithms on large scale knowledge graphs

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arXiv 2020年

作者： Dörpinghaus, Jens Stefan, Andreas Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin Germany

Knowledge graphs have been shown to play an important role in recent knowledge mining and discovery, for example in the field of life sciences or bioinformatics. Although a lot of research has been done on the field of query optimization, query transformation and of course in storing and retrieving large scale knowledge graphs the field of algorithmic optimization is still a major challenge and a vital factor in using graph databases. Few researchers have addressed the problem of optimizing algorithms on large scale labeled property graphs. Here, we present two optimization approaches and compare them with a naive approach of directly querying the graph database. The aim of our work is to determine limiting factors of graph databases like Neo4j and we describe a novel solution to tackle these challenges. For this, we suggest a classification schema to differ between the complexity of a problem on a graph database. We evaluate our optimization approaches on a test system containing a knowledge graph derived biomedical publication data enriched with text mining data. This dense graph has more than 71M nodes and 850M relationships. The results are very encouraging and – depending on the problem – we were able to show a speedup of a factor between 44 and 3839. Copyright © 2020, The Authors. All rights reserved.

关键词： Knowledge graph

Towards context in large scale biomedical knowledge graphs

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arXiv 2020年

作者： Dörpinghaus, Jens Stefan, Andreas Schultz, Bruce Jacobs, Marc Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin Germany

Contextual information is widely considered for NLP and knowledge discovery in life sciences since it highly influences the exact meaning of natural language. The scientific challenge is not only to extract such context data, but also to store this data for further query and discovery approaches. Here, we propose a multiple step knowledge graph approach using labeled property graphs based on polyglot persistence systems to utilize context data for context mining, graph queries, knowledge discovery and extraction. We introduce the graph-theoretic foundation for a general context concept within semantic networks and show a proof-of-concept based on biomedical literature and text mining. Our test system contains a knowledge graph derived from the entirety of PubMed and SCAIView data and is enriched with text mining data and domain specific language data using BEL. Here, context is a more general concept than annotations. This dense graph has more than 71M nodes and 850M relationships. We discuss the impact of this novel approach with 27 real world use cases represented by graph queries. Copyright © 2020, The Authors. All rights reserved.

关键词： Data mining

Stability of white holes revisited

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arXiv 2018年

作者： Nikitin, Igor Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53757 Germany

It is shown that the models of white hole interacting with external matter can be made stable by introduction of a negative central mass. Similar results are obtained for the models of white hole, interacting with null shells, with radial flows of matter and with photon gas. In realistic models, a naked timelike singularity corresponding to the negative mass is hidden under a coat of positive mass, providing an extremely strong redshift for photons born in the Planck neighborhood of the singularity and observed at infinity, thereby realizing the principle of cosmic censorship in a relaxed form. Copyright © 2018, The Authors. All rights reserved.

关键词： Stars

Wormholes and Teleporters

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arXiv 2021年

作者： Nikitin, Igor Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53757 Germany

In general relativity, there is a class of solutions that currently do not have observed analogues, but on which the theory is shaped, giving an understanding what is fundamentally possible within its framework. Such solutions include wormholes, tunnels that connect distant regions in spacetime. Although not a single wormhole has yet been discovered, there is a large number of works devoted to their study, thanks to which wormholes as a class of solutions become firmly established in modern science. In this paper, we consider two topologically nontrivial types of solutions related to wormholes. First: Wormholes that can open and close. In this relation, we will discuss topological censorship theorems, which under certain conditions prohibit changing topology. We will also discuss known ways to circumvent these theorems. Using analytical and numerical methods, as well as visualization, we will construct an example of an opening and closing wormhole with the dimensions of the central black hole in the Milky Way galaxy. Our construction continues the work by Kardashev, Novikov and Shatskiy, in which a static wormhole with the same parameters was considered. The second type is a modification of Visser's dihedral wormhole solution for a dynamic case, which can be considered as a model of a teleportation event. © 2021, CC BY.

关键词： Topology