Exact solutions for the Einstein-Gauss-Bonnet theory in five dimensions: Black holes, wormholes and spacetime horns

An exhaustive classification of certain class of static solutions for the five-dimensional Einstein-Gauss-Bonnet theory in vacuum is presented. The class of metrics under consideration is such that the spacelike section is a warped product of the real line with a nontrivial base manifold. It is shown that for generic values of the coupling constants the base manifold must be necessarily of constant curvature, and the solution reduces to the topological extension of the Boulware-Deser metric. It is also shown that the base manifold admits a wider class of geometries for the special case when the Gauss-Bonnet coupling is properly tuned in terms of the cosmological and Newton constants. This freedom in the metric at the boundary, which determines the base manifold, allows the existence of three main branches of geometries in the bulk. For negative cosmological constant, if the boundary metric is such that the base manifold is arbitrary, but fixed, the solution describes black holes whose horizon geometry inherits the metric of the base manifold. If the base manifold possesses a negative constant Ricci scalar, two different kinds of wormholes in vacuum are obtained. For base manifolds with vanishing Ricci scalar, a different class of solutions appears resembling "spacetime horns". There is also a special case for which, if the base manifold is of constant curvature, due to certain class of degeneration of the field equations, the metric admits an arbitrary redshift function. For wormholes and spacetime horns, there are regions for which the gravitational and centrifugal forces point towards the same direction. All these solutions have finite Euclidean action, which reduces to the free energy in the case of black holes, and vanishes in the other cases. Their mass is also obtained from a surface integral.Comment: 31 pages, 1 figure, minor changes and references added. Final version to be published in PR

Higher Dimensional Gravity, Propagating Torsion and AdS Gauge Invariance

The most general theory of gravity in d-dimensions which leads to second order field equations for the metric has [(d-1)/2] free parameters. It is shown that requiring the theory to have the maximum possible number of degrees of freedom, fixes these parameters in terms of the gravitational and the cosmological constants. In odd dimensions, the Lagrangian is a Chern-Simons form for the (A)dS or Poincare groups. In even dimensions, the action has a Born-Infeld-like form. Torsion may occur explicitly in the Lagrangian in the parity-odd sector and the torsional pieces respect local (A)dS symmetry for d=4k-1 only. These torsional Lagrangians are related to the Chern-Pontryagin characters for the (A)dS group. The additional coefficients in front of these new terms in the Lagrangian are shown to be quantized.Comment: 10 pages, two columns, no figures, title changed in journal, final version to appear in Class. Quant. Gra

Supersymmetry of gravitational ground states

A class of black objects which are solutions of pure gravity with negative cosmological constant are classified through the mapping between the Killing spinors of the ground state and those of the transverse section. It is shown that these geometries must have transverse sections of constant curvature for spacetime dimensions d below seven. For d > 6, the transverse sections can also be Euclidean Einstein manifolds. In even dimensions, spacetimes with transverse section of nonconstant curvature exist only in d = 8 and 10. This classification goes beyond standard supergravity and the eleven dimensional case is analyzed. It is shown that if the transverse section has negative scalar curvature, only extended objects can have a supersymmetric ground state. In that case, some solutions are explicitly found whose ground state resembles a wormhole.Comment: 16 pages, CECS style, minor correction

Reproductions of Nahua Manuscripts

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One Month, One Class, No Bags

According to the website, theworldcounts.com, we consume about 5 trillion plastic bags per year. This translates to roughly 160,000 bags per second. This rapidly increasing consumption of plastics has led to the harming of natural ecosystems and the endangerment of many species. At the College of DuPage, our Honors English Composition class decided to address this issue and propose a solution at the local level. As a class, we broke up into several research groups, each tackling a different section of research related to plastic bags: its history, nationwide legislation, counterarguments, and connection to Illinois’ plastic bag legislation. The groups gathered news articles and legislative documents, as well as conducted interviews and surveys to understand plastic bag consumption and its impacts on the environment. We also participated in what we called the “Plastic Bag Challenge”, where we refrained from using plastic bags for one month. Each student recorded video diaries to recount their experiences, as well as conflicts and obstacles that surfaced. Once the research component of our project was complete, we brainstormed ways to present our findings to the public. Our goal was to persuade the State of Illinois to enact legislation banning the use of plastic bags. During our course, we studied the history of rhetoric, its persuasive appeals and the effectiveness of the classical argument. We knew our argument would use rhetoric and follow the structure of the “classical argument” to persuade our audience. However, the presentation of this structural argument was something we had to discuss as a class; we wanted something that would be able to reach a large audience. We decided to create a video and a website that would present our research and advocate for the ban of plastic bags in Illinois. We formed two main groups to finish this part of the project -- one to make the video and the other to make the website. Once we were finished, we critiqued the projects before releasing them to the public. However, our work was not done when we published the video and website. We analyzed the public feedback (or lack thereof), and the results were somewhat disappointing. Our video received about 100 views, with 14 likes and 1 dislike. The video analytics also showed that we lost most viewers one minute into the video. While the results themselves were not very promising, we gained a favorable learning experience. The results led to a class discussion on why our project was not as successful as we wanted and ways we could have improved it. Now, we hope to inform our audience at the HCIR Student Symposium about our experience with trying to develop a rhetorical argument in modern-day society

Comparing species detection success between molecular markers in DNA metabarcoding of coastal macroinvertebrates

DNA metabarcoding has great potential to improve marine biomonitoring programs by providing a rapid and accurate assessment of species composition in zoobenthic communities. However, some methodological improvements are still required, especially regarding failed detections, primers efficiency and incompleteness of databases. Here we assessed the efficiency of two different marker loci (COI and 18S) and three primer pairs in marine species detection through DNA metabarcoding of the macrozoobenthic communities colonizing three types of artificial substrates (slate, PVC and granite), sampled between 3 and 15 months of deployment. To accurately compare detection success between markers, we also compared the representativeness of the detected species in public databases and revised the reliability of the taxonomic assignments. Globally, we recorded extensive complementarity in the species detected by each marker, with 69% of the species exclusively detected by either 18S or COI. Individually, each of the three primer pairs recovered, at most, 52% of all species detected on the samples, showing also different abilities to amplify specific taxonomic groups. Most of the detected species have reliable reference sequences in their respective databases (82% for COI and 72% for 18S), meaning that when a species was detected by one marker and not by the other, it was most likely due to faulty amplification, and not by lack of matching sequences in the database. Overall, results showed the impact of marker and primer applied on species detection ability and indicated that, currently, if only a single marker or primer pair is employed in marine zoobenthos metabarcoding, a fair portion of the diversity may be overlooked.project ATLANTIDA – Platform for the monitoring of the North Atlantic Ocean and tools for the sustainable exploitation of the marine resources, with the reference NORTE-01-0145-FEDER-000040, co-financed by the European Regional Development Fund (ERDF), through Programa Operacional Regional do Norte (NORTE 2020). BRL benefitted from an FCT fellowship PD/BD/127994/2016. The authors would like to thank Sofia Duarte (University of Minho) for the availability and support during practical stages of the research

Artificial seaweed substrates complement ARMS in DNA metabarcoding-based monitoring of temperate coastal macrozoobenthos

We used DNA metabarcoding to compare macrozoobenthic species colonization between autonomous reef monitoring structures (ARMS) and artificial seaweed monitoring systems (ASMS). We deployed both substrates in two different locations (Ría de Vigo and Ría de Ferrol, NW Iberian coast) and collected them after 6, 9, and 12 months to assess species composition of the colonizing communities through high-throughput sequencing of amplicons within the barcode region of the mitochondrial cytochrome c oxidase I (COI-5P) and the V4 domain of the 18S rRNA genes. We observed a consistently low similarity in species composition between substrate types, independently of sampling times and sites. A large fraction of exclusive species was recorded for a given substrate (up to 72%), whereas only up to 32% of species were recorded in both substrates. The shape and structural complexity of the substrate strongly affected the colonization preferences, with ASMS detecting more exclusive crustacean and gastropod species and a broader diversity of taxonomic groups (e.g., Entoprocta and Pycnogonida were detected exclusively in ASMS). We demonstrate that despite the customary use of ARMS for macrozoobenthos monitoring, by using ASMS we complemented the recovery of species and enlarged the scope of the taxonomic diversity recorded.This study was supported by the project ATLANTIDA (NORTE-01-0145-FEDER-000040), funded by Programa Operacional Regional do Norte (NORTE2020) and by the “Contrato-Programa” UIDB/04050/2020 funded by national funds through the FCT I.P. (Foundation for Science and Technology). Financial support granted by the FCT to BRL (PD/BD/127994/2016) and SD (CEECIND/00667/2017) is also acknowledged.We would like to thank all the members of the Marine Biology Station of A Graña and all the members of the ECIMAT Marine Station for providing the resources and support during sampling campaigns. We also acknowledge the two anonymous reviewers for their valuable comments

Black holes with topologically nontrivial AdS asymptotics

Asymptotically locally AdS black hole geometries of dimension d > 2 are studied for nontrivial topologies of the transverse section. These geometries are static solutions of a set of theories labeled by an integer 0 < k < [(d-1)/2] which possess a unique globally AdS vacuum. The transverse sections of these solutions are d-2 surfaces of constant curvature, allowing for different topological configurations. The thermodynamic analysis of these solutions reveals that the presence of a negative cosmological constant is essential to ensure the existence of stable equilibrium states. In addition, it is shown that these theories are holographically related to [(d-1)/2] different conformal field theories at the boundary.Comment: 13 Pages, 3 figures, two columns, Revtex, last version for PR

Effectively four-dimensional spacetimes emerging from d=5 Einstein-Gauss-Bonnet Gravity

Einstein-Gauss-Bonnet gravity in five-dimensional spacetime provides an excellent example of a theory that, while including higher-order curvature corrections to General Relativity, still shares many of its features, such as second-order field equations for the metric. We focus on the largely unexplored case where the coupling constants of the theory are such that no constant-curvature solution is allowed, leaving open the question of what the vacuum state should then be. We find that even a slight deviation from the anti-de Sitter Chern-Simons theory, where the vacuum state is five-dimensional AdS spacetime, leads to a complete symmetry breakdown, with the fifth dimension either being compactified into a small circle or shrinking away exponentially with time. A complete family of solutions, including duality relations among them, is uncovered and shown to be unique within a certain class. This dynamical dimensional reduction scenario seems particularly attractive as a means for higher-dimensional theories to make contact with our four-dimensional world.Comment: 9 pages, 4 figures. v2: New section on geometrical significance of solutions. Final version for CQ

Utilización de cotilos 3D en defectos acetabulares graves

Introducción: Ante el aumento de las artroplastias de cadera en el último siglo, los defectos acetabulares graves son eventos cada vez más frecuentes. Su tratamiento representa un verdadero desafío, debido al déficit y la pobre calidad ósea, habitual en estos pacientes. Materiales y Métodos: Se presentan 6 pacientes tratados entre 2016 y 2021. Cinco casos de disrupción pélvica por revisiones fallidas, clasificadas como tipo IIIB de Paprosky y una fractura transversal de acetábulo, posible opción de tratamiento en casos de pacientes osteoporóticos. Resultados: Los pacientes tratados con esta técnica multidisciplinaria fueron controlados durante un promedio de 20 meses, ninguno presentó complicaciones posoperatorias. Los resultados valorados con escalas analógicas son prometedores e invitan a establecer este procedimiento como el patrón de referencia. Conclusiones: La evaluación estricta es necesaria en los defectos acetabulares. La inclusión de ingeniería informática médica permite estudiar la necesidad de usar injerto de banco, fabricar implantes a medida de titanio/tantalio trabecular multiporos, lo que es ideal para lograr la osteointegración, sumado a la posibilidad de planificar la dirección y la longitud de los tornillos al hueso remanente, según su calidad. La cementación de un cotilo de doble movilidad dentro del implante a medida disminuye el riesgo de luxación y de sobrecarga de este último, al eliminar la fricción metal-metal