Windows on Quantum Gravity Álvarez, Enrique
Fortschritte der Physik,
January 2021, 2021-01-00, 20210101, Letnik:
69, Številka:
1
Journal Article
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These are notes for a graduate course in quantum gravity planned at IFT‐UAM/CSIC for the spring term of 2020, but delayed for an indefinite period of time (although a shortened version was given in ...the Escuela de Física (Institute of Physics) in the University of Costa Rica.). The aim of the course was to highlight the most important conceptual problems in the field and to summarize some of the most imaginative solutions to them that have been proposed in the literature. The course can best be characterized as idiosyncratic rather than encyclopedic.
These are notes for a graduate course in quantum gravity planned at IFT‐UAM/CSIC for the spring term of 2020, but delayed for an indefinite period of time (although a shortened version was given in the Escuela de Física (Institute of Physics) in the University of Costa Rica.). The aim of the course was to highlight the most important conceptual problems in the field and to summarize some of the most imaginative solutions to them that have been proposed in the literature. The course can best be characterized as idiosyncratic rather than encyclopedic.
Selenium and selenocompounds have attracted the attention and the efforts of scientists worldwide due to their promising potential applications in cancer prevention and/or treatment. Different ...organic selenocompounds, with diverse functional groups that contain selenium, have been reported to exhibit anticancer and/or chemopreventive activity. Among them, selenocyanates, selenoureas, selenoesters, selenium-containing heterocycles, selenium nanoparticles, selenides and diselenides have been considered in the search for efficiency in prevention and treatment of cancer and other related diseases. In this review, we focus our attention on the potential applications of selenides and diselenides in cancer prevention and treatment that have been reported so far. The around 80 selenides and diselenides selected herein as representative compounds include promising antioxidant, prooxidant, redox-modulating, chemopreventive, anticancer, cytotoxic and radioprotective compounds, among other activities. The aim of this work is to highlight the possibilities that these novel organic selenocompounds can offer in an effort to contribute to inspire medicinal chemists in their search of new promising derivatives.
Several formulations of the first order approach to unimodular gravity are presented. There is always a particular one such that it is classically equivalent to the second order formulation; this we ...call educated. It is often at variance with the naive approach, in which the Lagrangian is taken as given exactly by the same expression as in the second order formulation; only the number and character of the independent variables changes. Namely, typically some of the momenta are now considered as coordinates. The ensuing Hamiltonians are thereby discussed, and their physical differences pointed out.
Accurate noninvasive blood pressure (BP) measurements are vital in preventing and treating many cardiovascular diseases. The "gold standard" for noninvasive procedures is the auscultatory method, ...which is based on detecting Korotkoff sounds while deflating an arm cuff. Using this method as a "gold standard" requires highly trained technicians and has an intrinsic uncertainty in its BP predictions. In this article, we analyze and characterize the origins of this uncertainty. This article defines an uncertainty model for two consecutive BP measurements. Our research group developed a computer-based simulation of auscultatory BP measurement uncertainty, and these results were compared to a human-subject experiment with a group of 20 diverse-conditioned individuals. Uncertainties were categorized and quantified. The total computer-simulated uncertainty ranged between −8.4 and 8.4 mmHg in systolic BP (SBP) and −8.4 and 8.3 mmHg in diastolic BP (DBP) at a 95% confidence interval (CI), while the limits in the human-based study ranged from −8.3 to 8.3 mmHg in SBP and −16.7 to 4.2 mmHg in DBP.
Abstract
The divergences coming from a particular sector of gravitational fluctuations around a generic background in general theories of quadratic gravity are analyzed. They can be summarized in a ...particular type of scalar model, whose properties are discussed. We analyze in particular with some care arguments against this particular scalar model being unitary. We also discussed the product anomaly in this context.
Abstract The multi-domain non-structural protein 3 of SARS-coronavirus is a component of the viral replication/transcription complex (RTC). Among other domains, it contains three sequentially ...arranged macrodomains: the X domain and subdomains SUD-N as well as SUD-M within the “SARS-unique domain”. The X domain was proposed to be an ADP-ribose-1”-phosphatase or a poly(ADP-ribose)-binding protein, whereas SUD-NM binds oligo(G)-nucleotides capable of forming G-quadruplexes. Here, we describe the application of a reverse genetic approach to assess the importance of these macrodomains for the activity of the SARS-CoV RTC. To this end, Renilla luciferase-encoding SARS-CoV replicons with selectively deleted macrodomains were constructed and their ability to modulate the RTC activity was examined. While the SUD-N and the X domains were found to be dispensable, the SUD-M domain was crucial for viral genome replication/transcription. Moreover, alanine replacement of charged amino-acid residues of the SUD-M domain, which are likely involved in G-quadruplex-binding, caused abrogation of RTC activity.
Despite of the progress that has been made in the field, the problem of adversarial attacks remains unresolved. The most up-to-date models are still vulnerable, and there is not a simple way to ...defend against these kinds of attacks; even transformers can be affected by this problem, although they have not been extensively studied yet. In this paper, we study transferability, which is a property of adversarial attacks in which images generated for one architecture can be transferred to another and still be effective. In real-world scenarios like self-driving cars, malware detection, and face recognition authentication systems, transferability can lead to security issues. In order to conduct a behavioral analysis, we select a diverse set of networks and measure how effectively the images produced by various attacks can be transferred among them. We generate adversarial samples for each network and then evaluate them with other networks to determine the corresponding transferability performance. We can observe that all networks are susceptible to transferability attacks, albeit in some cases at the expense of severely distorted images.
It is well-known that in unimodular gravity (UG) the cosmological constant is not sourced by a constant energy density, but rather appears as some sort of integration constant. In this work we try to ...flesh this out by studying in some detail a couple of examples, one from cosmology and the other from gravitational collapse.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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