1. The document describes a known solution to Einstein's field equations that represents the formation of non-spherical black holes through the collapse of pure electromagnetic monochromatic radiation.
2. The solution describes a metric with electromagnetic radiation modeled as a null electromagnetic field. The radiation can be linearly, circularly, or elliptically polarized depending on the choice of functions.
3. The metric can describe the formation of black holes in anti-de Sitter space, the destruction of naked singularities, or the evaporation of white holes through the ingoing or outgoing flow of electromagnetic radiation.
On elements of deterministic chaos and cross links in non- linear dynamical s...iosrjce
In this paper we examine the existing definitions of deterministic chaos and the characterisation of
its various ingredients. We then make use of some classical examples to provide cross links between the
different chaotic behaviour of some simple but interesting maps which are then explained in a precise manner.
I am Samantha K. I am a Physics Assignment Expert at eduassignmenthelp.com. I hold a Ph.D. in Physics, from McGill University, Canada. I have been helping students with their homework for the past 8 years. I solve assignments related to Physics.
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I am Anthony F. I am a Digital Signal Processing Assignment Expert at matlabassignmentexperts.com. I hold a Ph.D. in Matlab, University of Cambridge, UK. I have been helping students with their homework for the past 8 years. I solve assignments related to Digital Signal Processing.
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IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
On elements of deterministic chaos and cross links in non- linear dynamical s...iosrjce
In this paper we examine the existing definitions of deterministic chaos and the characterisation of
its various ingredients. We then make use of some classical examples to provide cross links between the
different chaotic behaviour of some simple but interesting maps which are then explained in a precise manner.
I am Samantha K. I am a Physics Assignment Expert at eduassignmenthelp.com. I hold a Ph.D. in Physics, from McGill University, Canada. I have been helping students with their homework for the past 8 years. I solve assignments related to Physics.
Visit eduassignmenthelp.com or email info@eduassignmenthelp.com.
You can also call on +1 678 648 4277 for any assistance with Physics Assignments.
I am Anthony F. I am a Digital Signal Processing Assignment Expert at matlabassignmentexperts.com. I hold a Ph.D. in Matlab, University of Cambridge, UK. I have been helping students with their homework for the past 8 years. I solve assignments related to Digital Signal Processing.
Visit matlabassignmentexperts.com or email info@matlabassignmentexperts.com.
You can also call on +1 678 648 4277 for any assistance with Digital Signal Processing Assignments.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Contact geometry is the study of certain geometric structures on odd dimensional smooth manifolds. A contact structure is a hyperplane field specified by a one form which satisfies a maximum nondegeneracy condition called complete non-integrability. The associated one form is called a contact form and uniquely determines a Hamiltonian-like vector field called the Reeb vector field on the manifold. I will give some background on this subject, including motivation from classical mechanics. I will also explain how to make use of J-holomorphic curves to obtain a Floer theoretic contact invariant, contact homology, whose chain complex is generated by closed Reeb orbits. This talk will feature numerous graphics to acclimate people to the realm of contact geometry.
Computation of electromagnetic fields scattered from dielectric objects of un...Alexander Litvinenko
Computational tools for characterizing electromagnetic scattering from objects with uncertain shapes are needed in various applications ranging from remote sensing at microwave frequencies to Raman spectroscopy at optical frequencies. Often, such computational tools use the Monte Carlo (MC) method to sample a parametric space describing geometric uncertainties. For each sample, which corresponds to a realization of the geometry, a deterministic electromagnetic solver computes the scattered fields. However, for an accurate statistical characterization the number of MC samples has to be large. In this work, to address this challenge, the continuation multilevel Monte Carlo (\CMLMC) method is used together with a surface integral equation solver.
The \CMLMC method optimally balances statistical errors due to sampling of
the parametric space, and numerical errors due to the discretization of the geometry using a hierarchy of discretizations, from coarse to fine.
The number of realizations of finer discretizations can be kept low, with most samples
computed on coarser discretizations to minimize computational cost.
Consequently, the total execution time is significantly reduced, in comparison to the standard MC scheme.
This presentation is about electromagnetic fields, history of this theory and personalities contributing to this theory. Applications of electromagnetism. Vector Analysis and coordinate systems.
This article continues the study of concrete algebra-like structures in our polyadic approach, where the arities of all operations are initially taken as arbitrary, but the relations between them, the arity shapes, are to be found from some natural conditions ("arity freedom principle"). In this way, generalized associative algebras, coassociative coalgebras, bialgebras and Hopf algebras are defined and investigated. They have many unusual features in comparison with the binary case. For instance, both the algebra and its underlying field can be zeroless and nonunital, the existence of the unit and counit is not obligatory, and the dimension of the algebra is not arbitrary, but "quantized". The polyadic convolution product and bialgebra can be defined, and when the algebra and coalgebra have unequal arities, the polyadic version of the antipode, the querantipode, has different properties. As a possible application to quantum group theory, we introduce the polyadic version of braidings, almost co-commutativity, quasitriangularity and the equations for the R-matrix (which can be treated as a polyadic analog of the Yang-Baxter equation). Finally, we propose another concept of deformation which is governed not by the twist map, but by the medial map, where only the latter is unique in the polyadic case. We present the corresponding braidings, almost co-mediality and M-matrix, for which the compatibility equations are found.
A Tau Approach for Solving Fractional Diffusion Equations using Legendre-Cheb...iosrjce
In this paper, a modified numerical algorithm for solving the fractional diffusion equation is
proposed. Based on Tau idea where the shifted Legendre polynomials in time and the shifted Chebyshev
polynomials in space are utilized respectively.
The problem is reduced to the solution of a system of linear algebraic equations. From the computational point
of view, the solution obtained by this approach is tested and the efficiency of the proposed method is confirmed.
Contact geometry is the study of certain geometric structures on odd dimensional smooth manifolds. A contact structure is a hyperplane field specified by a one form which satisfies a maximum nondegeneracy condition called complete non-integrability. The associated one form is called a contact form and uniquely determines a Hamiltonian-like vector field called the Reeb vector field on the manifold. I will give some background on this subject, including motivation from classical mechanics. I will also explain how to make use of J-holomorphic curves to obtain a Floer theoretic contact invariant, contact homology, whose chain complex is generated by closed Reeb orbits. This talk will feature numerous graphics to acclimate people to the realm of contact geometry.
Computation of electromagnetic fields scattered from dielectric objects of un...Alexander Litvinenko
Computational tools for characterizing electromagnetic scattering from objects with uncertain shapes are needed in various applications ranging from remote sensing at microwave frequencies to Raman spectroscopy at optical frequencies. Often, such computational tools use the Monte Carlo (MC) method to sample a parametric space describing geometric uncertainties. For each sample, which corresponds to a realization of the geometry, a deterministic electromagnetic solver computes the scattered fields. However, for an accurate statistical characterization the number of MC samples has to be large. In this work, to address this challenge, the continuation multilevel Monte Carlo (\CMLMC) method is used together with a surface integral equation solver.
The \CMLMC method optimally balances statistical errors due to sampling of
the parametric space, and numerical errors due to the discretization of the geometry using a hierarchy of discretizations, from coarse to fine.
The number of realizations of finer discretizations can be kept low, with most samples
computed on coarser discretizations to minimize computational cost.
Consequently, the total execution time is significantly reduced, in comparison to the standard MC scheme.
This presentation is about electromagnetic fields, history of this theory and personalities contributing to this theory. Applications of electromagnetism. Vector Analysis and coordinate systems.
This article continues the study of concrete algebra-like structures in our polyadic approach, where the arities of all operations are initially taken as arbitrary, but the relations between them, the arity shapes, are to be found from some natural conditions ("arity freedom principle"). In this way, generalized associative algebras, coassociative coalgebras, bialgebras and Hopf algebras are defined and investigated. They have many unusual features in comparison with the binary case. For instance, both the algebra and its underlying field can be zeroless and nonunital, the existence of the unit and counit is not obligatory, and the dimension of the algebra is not arbitrary, but "quantized". The polyadic convolution product and bialgebra can be defined, and when the algebra and coalgebra have unequal arities, the polyadic version of the antipode, the querantipode, has different properties. As a possible application to quantum group theory, we introduce the polyadic version of braidings, almost co-commutativity, quasitriangularity and the equations for the R-matrix (which can be treated as a polyadic analog of the Yang-Baxter equation). Finally, we propose another concept of deformation which is governed not by the twist map, but by the medial map, where only the latter is unique in the polyadic case. We present the corresponding braidings, almost co-mediality and M-matrix, for which the compatibility equations are found.
A Tau Approach for Solving Fractional Diffusion Equations using Legendre-Cheb...iosrjce
In this paper, a modified numerical algorithm for solving the fractional diffusion equation is
proposed. Based on Tau idea where the shifted Legendre polynomials in time and the shifted Chebyshev
polynomials in space are utilized respectively.
The problem is reduced to the solution of a system of linear algebraic equations. From the computational point
of view, the solution obtained by this approach is tested and the efficiency of the proposed method is confirmed.
Within the framework of the general theory of relativity (GR) the modeling of the central symmetrical
gravitational field is considered. The mapping of the geodesic motion of the Lemetr and Tolman basis on
their motion in the Minkowski space on the world lines is determined. The expression for the field intensity
and energy where these bases move is obtained. The advantage coordinate system is found, the coordinates
and the time of the system coincide with the Galilean coordinates and the time in the Minkowski space.
Within the framework of the general theory of relativity (GR) the modeling of the central symmetrical
gravitational field is considered. The mapping of the geodesic motion of the Lemetr and Tolman basis on
their motion in the Minkowski space on the world lines is determined. The expression for the field intensity
and energy where these bases move is obtained. The advantage coordinate system is found, the coordinates
and the time of the system coincide with the Galilean coordinates and the time in the Minkowski space.
Também conhecido como o “Time Lock Puzzle”, o LCS35 é um desafio em forma de criptografia projetado em 1999 pelo pesquisador Ron Rivest, do Instituto de Tecnologia de Massachusetts (MIT). Quando este problema matemático for resolvido, uma cápsula do tempo de chumbo será aberta no MIT.
O puzzle envolve a divisão de um número incrivelmente enorme, por um número que é apenas um pouco menor que o da conta (mas ainda com mais de 600 dígitos).
Ninguém sabe o que está dentro da capsula e, segundo os dados de Rivest, estima-se que levaria cerca de 35 anos para que o enigma seja resolvido. Os interessados ainda terão de esperar para descobrir o que de fato tem na capsula.
Wow! Signal Decoded as Foundations of Theory of EverythingXequeMateShannon
The Wow! signal was a strong narrowband radio signal received on August 15, 1977, by Ohio State University's Big Ear radio telescope in the United States, then used to support the search for extraterrestrial intelligence. The signal appeared to come from the constellation Sagittarius and bore the expected hallmarks of extraterrestrial origin.
Em Matemática, um número normal é um número real cujos algarismos são distribuídos de maneira aleatória no seu desenvolvimento decimal, isto é, os algarismos aparecem todos com a mesma freqüência. Os "algarismos" se referem aos algarismos antes da vírgula e a seqüência infinita de algarismos após a vírgula.
Um algoritmo genético é uma técnica de busca utilizada na ciência da computação para achar soluções aproximadas em problemas de otimização e busca, fundamentado principalmente pelo americano John Henry Holland.
Hamiltonian design in readout from room-temperature Raman atomic memory XequeMateShannon
We present an experimental demonstration of the Hamiltonian manipulation in light-atom interface in Raman-type warm rubidium-87 vapor atomic memory. By adjusting the detuning of the driving beam we varied the relative contributions of the Stokes and anti-Stokes scattering to the process of four-wave mixing which reads out a spatially multimode state of atomic memory. We measured the temporal evolution of the readout fields and the spatial intensity correlations between write-in and readout as a function of detuning with the use of an intensified camera. The correlation maps enabled us to resolve between the anti-Stokes and the Stokes scattering and to quantify their contributions. Our experimental results agree quantitatively with a simple, plane-wave theoretical model we provide. They allow for a simple interpretation of the coaction of the anti-Stokes and the Stokes scattering at the readout stage. The Stokes contribution yields additional, adjustable gain at the readout stage, albeit with inevitable extra noise. Here we provide a simple and useful framework to trace it and the results can be utilized in the existing atomic memories setups. Furthermore, the shown Hamiltonian manipulation offers a broad range of atom-light interfaces readily applicable in current and future quantum protocols with atomic ensembles.
Good cryptography requires good random numbers. This paper evaluates the hardwarebased Intel Random Number Generator (RNG) for use in cryptographic applications.
Almost all cryptographic protocols require the generation and use of secret values that must be unknown to attackers. For example, random number generators are required to generate public/private keypairs for asymmetric (public key) algorithms including RSA, DSA, and Diffie-Hellman. Keys for symmetric and hybrid cryptosystems are also generated randomly. RNGs are also used to create challenges, nonces (salts), padding bytes, and blinding values. The one time pad – the only provably-secure encryption system – uses as much key material as ciphertext and requires that the keystream be generated from a truly random process.
A palavra aleatoriedade exprime quebra de ordem, propósito, causa, ou imprevisibilidade em uma terminologia não científica. Um processo aleatório é o processo repetitivo cujo resultado não descreve um padrão determinístico, mas segue uma distribuição de probabilidade.
Quantum cryptography can, in principle, provide unconditional security guaranteed by the law of physics only. Here, we survey the theory and practice of the subject and highlight some recent developments.
The Security of Practical Quantum Key DistributionXequeMateShannon
Quantum key distribution (QKD) is the first quantum information task to reach the level of mature technology, already fit for commercialization. It aims at the creation of a secret key between authorized partners connected by a quantum channel and a classical authenticated channel. The security of the key can in principle be guaranteed without putting any restriction on the eavesdropper's power.
The first two sections provide a concise up-to-date review of QKD, biased toward the practical side. The rest of the paper presents the essential theoretical tools that have been developed to assess the security of the main experimental platforms (discrete variables, continuous variables and distributed-phase-reference protocols).
Experimental realisation of Shor's quantum factoring algorithm using qubit r...XequeMateShannon
Quantum computational algorithms exploit quantum mechanics to solve problems exponentially faster than the best classical algorithms. Shor's quantum algorithm for fast number factoring is a key example and the prime motivator in the international effort to realise a quantum computer. However, due to the substantial resource requirement, to date, there have been only four small-scale demonstrations. Here we address this resource demand and demonstrate a scalable version of Shor's algorithm in which the n qubit control register is replaced by a single qubit that is recycled n times: the total number of qubits is one third of that required in the standard protocol. Encoding the work register in higher-dimensional states, we implement a two-photon compiled algorithm to factor N=21. The algorithmic output is distinguishable from noise, in contrast to previous demonstrations. These results point to larger-scale implementations of Shor's algorithm by harnessing scalable resource reductions applicable to all physical architectures.
The usual theory of inflation breaks down in eternal inflation. We derive a dual description of eternal inflation in terms of a deformed Euclidean CFT located at the threshold of eternal inflation. The partition function gives the amplitude of different geometries of the threshold surface in the no-boundary state. Its local and global behavior in dual toy models shows that the amplitude is low for surfaces which are not nearly conformal to the round three-sphere and essentially zero for surfaces with negative curvature. Based on this we conjecture that the exit from eternal inflation does not produce an infinite fractal-like multiverse, but is finite and reasonably smooth.
The different faces of mass action in virus assemblyXequeMateShannon
The spontaneous encapsulation of genomic and non-genomic polyanions by coat proteins of simple icosahedral viruses is driven, in the first instance, by electrostatic interactions with polycationic RNA binding domains on these proteins. The efficiency with which the polyanions can be encapsulated in vitro, and presumably also in vivo, must in addition be governed by the loss of translational and mixing entropy associated with co-assembly, at least if this co-assembly constitutes a reversible process. These forms of entropy counteract the impact of attractive interactions between the constituents and hence they counteract complexation. By invoking mass action-type arguments and a simple model describing electrostatic interactions, we show how these forms of entropy might settle the competition between negatively charged polymers of different molecular weights for co-assembly with the coat proteins. In direct competition, mass action turns out to strongly work against the encapsulation of RNAs that are significantly shorter, which is typically the case for non-viral (host) RNAs. We also find that coat proteins favor forming virus particles over nonspecific binding to other proteins in the cytosol even if these are present in vast excess. Our results rationalize a number of recent in vitro co-assembly experiments showing that short polyanions are less effective at attracting virus coat proteins to form virus-like particles than long ones do, even if both are present at equal weight concentrations in the assembly mixture.
A Digital Signature Based on a Conventional Encryption FunctionXequeMateShannon
A new digital signature based only on a conventional encryption function (such as DES) is described which is as secure as the underlying encryption function -- the security does not depend on the difficulty of factoring and the high computational costs of modular arithmetic are avoided. The signature system can sign an unlimited number of messages, and the signature size increases logarithmically as a function of the number of messages signed. Signature size in a ‘typical’ system might range from a few hundred bytes to a few kilobytes, and generation of a signature might require a few hundred to a few thousand computations of the underlying conventional encryption function.
Quantum algorithm for solving linear systems of equationsXequeMateShannon
Solving linear systems of equations is a common problem that arises both on its own and as a subroutine in more complex problems: given a matrix A and a vector b, find a vector x such that Ax=b. We consider the case where one doesn't need to know the solution x itself, but rather an approximation of the expectation value of some operator associated with x, e.g., x'Mx for some matrix M. In this case, when A is sparse, N by N and has condition number kappa, classical algorithms can find x and estimate x'Mx in O(N sqrt(kappa)) time. Here, we exhibit a quantum algorithm for this task that runs in poly(log N, kappa) time, an exponential improvement over the best classical algorithm.
Countermeasures Against High-Order Fault-Injection Attacks on CRT-RSAXequeMateShannon
In this paper we study the existing CRT-RSA countermeasures against fault-injection at-tacks. In an attempt to classify them we get to achieve deep understanding of how they work. We show that the many countermeasures that we study (and their variations) actually share a number of common features, but optimize them in different ways. We also show that there is no conceptual distinction between test-based and infective countermeasures and how either one can be transformed into the other. Furthermore, we show that faults on the code (skipping instructions) can be captured by considering only faults on the data. These intermediate results allow us to improve the state of the art in several ways: (a) we fix an existing and that was known to be broken countermeasure (namely the one from Shamir); (b) we drastically optimize an existing countermeasure (namely the one from Vigilant) which we reduce to 3 tests instead of 9 in its original version, and prove that it resists not only one fault but also an arbitrary number of randomizing faults; (c) we also show how to upgrade countermeasures to resist any given number of faults: given a correct first-order countermeasure, we present a way to design a prov-able high-order countermeasure (for a well-defined and reasonable fault model). Finally, we pave the way for a generic approach against fault attacks for any modular arithmetic computations, and thus for the automatic insertion of countermeasures.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Salas, V. (2024) "John of St. Thomas (Poinsot) on the Science of Sacred Theol...Studia Poinsotiana
I Introduction
II Subalternation and Theology
III Theology and Dogmatic Declarations
IV The Mixed Principles of Theology
V Virtual Revelation: The Unity of Theology
VI Theology as a Natural Science
VII Theology’s Certitude
VIII Conclusion
Notes
Bibliography
All the contents are fully attributable to the author, Doctor Victor Salas. Should you wish to get this text republished, get in touch with the author or the editorial committee of the Studia Poinsotiana. Insofar as possible, we will be happy to broker your contact.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Deep Software Variability and Frictionless Reproducibility
Black hole formation by incoming electromagnetic radiation
1. NOTE
Black hole formation by incoming electromagnetic
radiation
Jos´e M M Senovilla1
1
F´ısica Te´orica, Universidad del Pa´ıs Vasco, Apartado 644, 48080 Bilbao, Spain
E-mail: josemm.senovilla@ehu.es
Abstract. I revisit a known solution of the Einstein field equations to show that
it describes the formation of non-spherical black holes by the collapse of pure
electromagnetic monochromatic radiation. Both positive and negative masses are
feasible without ever violating the dominant energy condition. The solution can also
be used to model the destruction of naked singularities and the evaporation of white
holes by emission or reception of light.
PACS numbers: 04.70.Bw, 04.40.Nr, 04.20.Jb
Today there are many models describing the formation, or the evaporation, of black
holes in General Relativity, some of them deal with the collapse of matter or fluids, others
with out- or in-coming “incoherent radiation”. However, there is no identified case of the
formation/evaporation of a black hole by means of electromagnetic radiation solely. The
purpose of this sort Note is to call attention to a family of solutions which describe the
formation/destruction of black holes (also naked singularities) by reception or emission
of pure monochromatic light. Actually, the solution is known since long ago, and has
been used to describe the collapse of null dust to non-spherical black holes with negative
cosmological constant [13, 14], and to analyze the first example of a dynamical horizon
with toroidal topology [5]. However, the fundamental point is that the radiation can
be properly identified as monochromatic light —it should not be treated as “incoherent
radiation”.
The line-element of the solution was first presented —among many other exact
solutions— by Robinson and Trautman in their celebrated paper [22], and is given in
local coordinates {u, r, x, y} by (see also [24], p.430)
ds2
= r2
(dx2
+ dy2
) + 2 dvdr +
2m(v)
r
+
Λ
3
r2
dv2
(1)
where r > 0, = ±1 determines the retarded ( = −1) or advanced ( = 1) character of
the null coordinate v, k = −dv is a null one-form chosen to be future pointing, Λ is the
cosmological constant (allowed to have any sign) and m(v) is a function of v.
The metric (1) is a solution of the Einstein-Maxwell equations with Λ for a null
electromagnetic field given by
F = dv ∧ (hx(v)dx + hy(v)dy) (2)
arXiv:1408.2778v2[gr-qc]18Aug2014
2. Black hole formation by electromagnetic radiation 2
so that k is the wave vector of this pure radiation field. Here, hx(v) and hy(v) are
arbitrary functions. An appropriate observer with unit timelike tangent vector u
orthogonal to the {x, y} surfaces and with uµ
kµ = −1 will measure electric E and a
magnetic B fields given by
E = hx(v)dx + hy(v)dy, B = hy(v)dx − hx(v)dy .
Therefore, by choosing the functions hx, hy judiciously one can describe light that is
linearly polarized (e.g. hy = 0), circularly polarized (e.g. hx = A cos v, hy = A sin v), or
elliptically polarized.
The energy-momentum tensor of the electromagnetic radiation reads
Tµν =
h2
x(v) + h2
y(v)
r2
kµkν (3)
from where one determines the function m(v) on the line-element (1):
m(v) =
4πG
c4
v
v0
[h2
x(w) + h2
y(w)]dw + M (4)
where v0 is a fixed value of v and M = m(v0) is an integration constant (v0 can be −∞).
The energy-momentum tensor (3) always satisfies the dominant energy condition, and
we have
˙m(v) =
4πG
c4
[h2
x(v) + h2
y(v)]
where dots denote derivatives with respect to v, so that the function m(v) is non-
decreasing for = 1 and non-increasing for = −1. Observe that M can have any
sign.
The metric (1) is the unique Petrov type D solution of the Einstein-Maxwell
equations with a null electromagnetic field [25]. It must be remarked that there exists
no analogue solution in higher dimensions [21].
The space-time has three independent Killing vectors in general given by
{∂x, ∂y, y∂x − x∂y}, the corresponding isometry group acts transitively on spacelike 2-
dimensional surfaces spanned by {∂x, ∂y}. Thus, the third Killing vector is an isotropy.
There is also a Kerr-Schild vector field [4] ξ = ∂v satisfying
£ξgµν =
2 ˙m
r
kµkν £ξkµ = 0 . (5)
This vector field is analogous to the Kodama vector field in spherically symmetric
spacetimes [10, 1]. The electromagnetic field inherits the symmetry {∂x, ∂y} but not
the isotropy:
£y∂x−x∂y F = dv ∧ (hydx − hxdy), £ξF = dv ∧ ˙hxdx + ˙hydy .
Observe that the Kerr-Schild vector field is a symmetry of the electromagnetic field
whenever hx, hy are both constant, in which case the function m(v) is linear in v.
The surfaces of transitivity, defined by constant values of v and r, can describe (i)
flat tori if one identifies x ↔ x + a and y ↔ y + b, in which case they are compact
3. Black hole formation by electromagnetic radiation 3
with an area equal to abr2
; (ii) flat cylinders if only one of the previous identifications
is performed; and (iii) flat planes when −∞ < x, y < ∞. The mean curvature one-form
[11, 1] for these surfaces is simply H = dr from where their two future null expansions
can be easily extracted
θ1 = − , θ2 = −
2m(v)
r
+
Λ
3
r2
.
Hence, the surfaces of transitivity are trapped if and only if 2m/r + Λr2
/3 > 0. They
are future- or past-trapped for = 1 or −1, respectively. Notice that the transitivity
surfaces are always trapped for large enough r if Λ > 0 (de Sitter behavior at infinity),
and for small enough r if m(v) > 0 independently of the sign of Λ. Actually, they are
always trapped in the region with m(v) > 0 if Λ = 0. For Λ < 0, the transitivity surfaces
are trapped only in the region with 2m(v) > −Λr3
/3 > 0 if this exists, and they can
never be trapped for large enough r (anti-de Sitter behavior).
The hypersurface defined by
H : 2m(v) +
Λ
3
r3
= 0 (6)
(if this is feasible) is a marginally trapped tube, that is, a hypersurface foliated by
marginally trapped surfaces. Observe that H exists for Λ > 0, = 0 or < 0 only if m(v)
is negative, zero or positive, respectively, somewhere. One can easily compute the causal
character of H: it is non-spacelike if Λ > 0 and actually timelike or null whenever ˙m = 0
or ˙m = 0 respectively; non-timelike if Λ < 0 with null portions wherever ˙m = 0 and
spacelike parts where ˙m = 0, in the last case these parts are dynamical horizons [5]; if
Λ = 0 it is given by the null hypersurfaces v = ˆv such that m(ˆv) = 0.
There is a curvature singularity at r → 0 unless m(v) = 0 (in which case there is no
electromagnetic radiation). This particular case with m(v) = 0 has constant curvature
Λ/3, so that the metric represents a region of de Sitter, flat, or anti-de Sitter space-time
depending on the sign of Λ. In these cases r = 0 is actually a horizon through which the
metric is extendible. Black holes in anti-de Sitter space-time obtained by identification
along one symmetry generator were deeply analyzed in [6]. Other interesting particular
cases arise if the electromagnetic radiation is absent (hx = hy = 0) but we retain a
non-vanishing constant m(v) = M = 0. These are metrics describing planar, cylindrical
or toroidal black holes when Λ < 0, and have been largely studied in the literature
[7, 12, 3, 15, 17, 26, 9]. These cases, as follows from (5), have ξ as another Killing vector,
so that they are stationary outside H which is a Killing horizon in this situation. One
can check [7, 12, 3, 15, 17, 26, 9] that then m(v) = M is proportional to the mass in the
toroidal case, to mass per unit length in the cylindrical case, and to mass per unit area
in the planar case. Therefore, negative values of m(v) can be interpreted, at least when
Λ < 0, as negative values of the mass. Black holes with negative mass were discussed in
[16], but the remarkable thing about solution (1) is that the dominant energy condition
holds everywhere. This may be related to recent discussions on similar situations in de
Sitter backgrounds [2, 19]. When Λ = 0 but keeping m(v) = M the metric can be seen
4. Black hole formation by electromagnetic radiation 4
to be isometric to the Kasner space-time [24] with exponents p1 = p2 = 2/3, p3 = −1/3
if M > 0, and isometric to the plane-symmetric Taub solution [24] if M < 0.
The collapse to form non-spherical stationary black holes with a constant m(v) = M
and Λ < 0 has been studied in several papers, such as for instance in [23] where the
toroidal case treated herein was not explicitly considered but was later carried out in
[20]. In this reference [20], the collapse of perfect fluids describing anisotropic, as well
as spatially inhomogeneous, interiors was fully described by matching these interiors to
an exterior (1) with constant m(v) = M. A collapse by matching was also considered
in [13], where the dynamical metric (1) was studied without realizing that the incoming
flow of radiation is actually a null electromagnetic field, but this matching is incorrect.‡
The point I want to make in this sort Note is that the metric (1) describes,
appropriately, the generation of black holes by collapse of fully identified matter content:
pure electromagnetic monochromatic waves with a well defined polarization. And there
is no need for a matching procedure. Actually, this is just one situation of interest
among a rich family of different behaviors that can be properly represented by (1).
Some outstanding cases are enumerated and briefly analyzed next.
1. Formation of a toroidal, cylindrical or planar black hole by sending light into an
anti-de Sitter background By choosing Λ < 0, = 1 and letting hx(v) = hy(v) = 0 for
all v < v0 the function m(v) = M is constant for all v < v0. When M is set to zero
then the space-time is anti-de Sitter in this entire region. If light is then sent into the
space-time by letting hx(v), hy(v) to be non-zero in the interval v0 ≤ v ≤ v1, a black hole
enclosing a future singularity censored by an event horizon forms with a final constant
m(v) = Mf > 0 given by
Mf =
4πG
c4
v1
v0
[h2
x(v) + h2
y(v)]dv . (7)
A Penrose-like diagram of this example is given in figure 1.
2. Transformation of a naked singularity into a black hole enclosing a clothed singularity
by sending light into the former When M is not set to zero but rather is a negative
constant in the previous situation, the space-time has a naked timelike singularity at
r = 0 for all v ≤ v0. Sending light again as before, and assuming that
Mf =
4πG
c4
v1
v0
[h2
x(v) + h2
y(v)]dv + M (8)
is strictly positive, the singularity at r = 0 transmutes into a spacelike one clothed by
an event horizon which merges with the dynamical horizon H. An illustrative diagram
is presented in Figure 2. Similar situations arise for Λ > 0 and Λ = 0, but now without
‡ In [13] the metric (1) is claimed to be matched to an interior Robertson-Walker metric for dust.
However, this is impossible, as the Israel conditions [8, 18] for a matching would require that the
normal components of the energy momentum tensor be continuous at the matching hypersurface, and
this cannot happen with a dust on one side and (3) on the other side.
5. Black hole formation by electromagnetic radiation 5
r = 0 singularity
r
=
0
v
=
−
∞
v
=
v0
EH
E
H
v
=
v
1
H
AdS
AdS
J
Figure 1. Schematic diagram of the formation of a toroidal (cylindrical or planar)
black hole by sending light into an anti-de Sitter (AdS) background. As usual, null
radial lines are drawn at 45o
and the future direction is upwards. The spacetime
is AdS until monochromatic light enters from J (an infinity that is timelike) at
v = v0 and flows along null hypersurfaces until it ceases at v = v1. Thus, the shaded
region contains a non-vanishing energy-momentum content due to the electromagnetic
radiation solely. In the AdS part, the null hypersurfaces labeled as r = 0 and v = −∞
are horizons through which the space-time can be regularly extended. The spacetime
has a final mass proportional to Mf in (7). When the first photon reaches the r = 0-
horizon a dynamical horizon H develops that eventually (at v = v1) merges with the
event horizon EH of the black hole, which encloses a future spacelike singularity r = 0.
Observe that EH starts developing in the AdS region.
the formation of event horizons; in the former case there is a marginally trapped tube
H which is partly null and partly timelike but not in the latter. Moreover, in the former
case there is a past infinity J −
which is spacelike while in the latter it is null.
3. Annihilation of a naked singularity by sending a fine-tuned amount of light Under
the same assumptions as in the previous case, if M < 0 and hx(v), hy(v) are fine tuned
together with v1 − v0 such that the final Mf in (8) vanishes, the original timelike naked
singularity simply disappears and the final outcome is a portion of anti-de Sitter , de
Sitter, or flat space-time for negative, positive or vanishing Λ, respectively. The case
with Λ > 0 is the only one containing future trapped surfaces and a marginally trapped
tube H —which in this case is non-spacelike everywhere. Corresponding diagrams are
6. Black hole formation by electromagnetic radiation 6
r = 0 singularity
r=0singularity
J
v
=
ˆv
v
=
v
0
EH
E
Hv
=
v
1
H
Figure 2. Schematic diagram of the transmutation of a naked singularity into a
clothed one of a toroidal (cylindrical or planar) black hole by sending light into the
former. The spacetime has a naked timelike singularity at r = 0 with negative
m(v) = M until monochromatic light enters from infinity J at v = v0 and flows
along null hypersurfaces until it ceases at v = v1, so the shaded region contains
electromagnetic radiation solely. The spacetime has a final mass proportional to
Mf > 0 given in (8) and therefore there is a value v = ˆv where m(ˆv) = 0. When
the photons traveling along this hypersurface v = ˆv reach the naked singularity —as
shown— a dynamical horizon H develops that eventually (at v = v1) merges with the
event horizon EH of the black hole, enclosing a future spacelike singularity r = 0.
given in figure 3.
4. Time reversals By setting = −1 in (1) one describes situations where the
electromagnetic radiation is emitted outwardly towards the future; observe that now
˙m ≤ 0. Then, for instance, models for the evaporation of a white hole by pure emission
of light leading to anti-de Sitter space-time arise: this is simply the time reversal of
1. and the corresponding diagram is the same as in figure 1 but turned upside down.
Similarly, one can model the appearance of a naked timelike singularity in vacuum (with
arbitrary Λ) by spontaneous emission of photons. Again, these are the time reversals of
3. and the corresponding diagrams are the same as in figure 3 interchanging future and
past.
Acknowledgements
Thanks to I. Bengtsson for bringing [6] to my attention. Supported by grants FIS2010-
15492 (MICINN), GIU12/15 (Gobierno Vasco), P09-FQM-4496 (J. Andaluc´ıa—
FEDER) and UFI 11/55 (UPV/EHU).
7. Black hole formation by electromagnetic radiation 7
r=0singularityv
=
ˆv
=
v1
v
=
v
0
r
=
0
J
AdS
r=0singularity
v
=
∞
J −
v
=
ˆv
=
v1v
=
v
0
r
=
0
dS
H
H
r=0singularity
v
=
∞
J
−
v
=
ˆv
=
v
1
v
=
v
0
r
=
0
flat
Figure 3. Diagrams of the complete annihilation of naked timelike singularities leading
to a constant-curvature space-time. As in the previous figure, the spacetime has a
naked timelike singularity at r = 0 with negative m(v) = M until monochromatic light
enters from infinity J at v = v0 and stops flowing in at v = v1 = ˆv with m(ˆv) = 0, so
the shaded regions contain only electromagnetic radiation. The spacetimes possess a
final vanishing mass (m(v) = 0 for all v > ˆv) and therefore they become anti-de Sitter,
de Sitter or flat spacetimes according to whether Λ is negative, positive or vanishing.
These three cases are shown in that order from left to right. In the last two cases
the null hypersurface marked by v = ∞ is a regular horizon and the metric can be
extended beyond them. In all three cases the null hypersurfaces labeled as r = 0 are
horizons through which the space-time can be regularly extended too. A marginally
trapped tube H which is partly null and then timelike exists only in the case with
Λ > 0, as shown.
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