Geometric Knot Spaces and Polygonal Isotopy

The space of n-sided polygons embedded in three-space consists of a smooth manifold in which points correspond to piecewise linear or ``geometric'' knots, while paths correspond to isotopies which preserve the geometric structure of these knots. The topology of these spaces for the case n = 6 and n = 7 is described. In both of these cases, each knot space consists of five components, but contains only three (when n = 6) or four (when n = 7) topological knot types. Therefore ``geometric knot equivalence'' is strictly stronger than topological equivalence. This point is demonstrated by the hexagonal trefoils and heptagonal figure-eight knots, which, unlike their topological counterparts, are not reversible. Extending these results to the cases n \ge 8 is also discussed.Comment: AMS LaTeX, 23 pages, 14 figures, 1 table; submitted to Journal of Knot Theory and its Ramifications, and to Proceedings of the International Knot Theory Meeting (Knots in Hellas 1998), Delphi, Greece, 7 - 15 August 1998. Also available from http://www.williams.edu/Mathematics/jcalvo/abstract.htm

Novos restos de Notosuchus terrestris Woodward, 1896 (Crocodyliformes: Mesoeucrocodylia) do Cretáceo Superior de Neuquén, Patagônia, Argentina

New materials of Notosuchus terrestris are here described. They were found on Bajo de la Carpa Formation outcrops, near the Universidad Nacional del Comahue, Neuquén City. Descriptions were based on five specimens, one of them the only specimen of Notosuchus with postcranial remains articulated to the skull. As in Sphagesaurus, it presents triangular teeth in cross-section and oblique molariforms with worn facet surface. As in Mariliasuchus, it possesses procumbent mandibular incisiform teeth and, like in other notosuchians and basal crocodyliforms, it was able of proal mandibular movement. The centra of cervical vertebrae possess ventral keel as in Chimaerasuchus. Elongated cervical neural spines and suprapostzygapophyseal laminae in cervicodorsal vertebrae are observed. The scapular dorsal end is greatly enlarged, while the coracoid ventromedial process end is moderately developed. The dorsal surface of the ilium is lateromedially wide with a greatly expanded acetabular roof and a prominent anteromedial process in the femoral shaft. Based on diverse cranial and postcranial characters, we infer that Notosuchus possessed facial and perioral musculature well developed and an herbivore diet, confirming the suggestions of previous authors. Notosuchus represents, based on phylogenetic studies, the sister taxon of Mariliasuchus and the monophyly of Notosuchia is demonstrated. Paleobiogeographycally, the occurrence of Chimaerasuchus in China evidences the faunistic interchange between Gondwana and Central Asia during the Early Cretaceous.Novos materiais de Notosuchus terrestris são aqui descritos. Eles provêm de afloramentos da Formação Bajo de la Carpa, localizados próximos à Universidad Nacional del Comahue, na cidade de Neuquén. As descrições foram baseadas em cinco exemplares, um deles o único espécime de Notosuchus com restos pós-cranianos articulados ao crânio. Como em Sphagesaurus, N. terrestris apresenta dentes triangulares em seção cruzada e molariformes oblíquos com superfície da faceta com desgaste. Como em Mariliasuchus, a espécie possui dentes mandibulares incisiformes procumbentes e, como em outros notossúquios e crocodiliformes basais, era possível realizar o movimento antero-posterior mandibular. Os centros das vértebras cervicais possuem uma quilha ventral como em Chimaerasuchus. Espinhos neurais cervicais alongados e lâminas suprapószigapofiseais em vértebras cérvico-dorsais são observados. A extremidade escapular dorsal é amplamente alargada, enquanto a extremidade do processo ventro-medial do coracóide é pouco desenvolvida. A superfície dorsal do ilium é larga látero-medialmente com um teto acetabular amplamente expandido e processo ântero-medial proeminente na diáfise femoral. Baseado em diversos caracteres cranianos e pós-cranianos, infere-se que Notosuchus apresentava grande desenvolvimento da musculatura facial e perioral e tinha uma dieta herbívora, confirmando o que foi sugerido anteriormente por outros autores. Notosuchus representa, baseado em estudos filogenéticos, o táxon irmão de Mariliasuchus e a monofilia de Notosuchia é demonstrada. Paleobiogeograficamente, a ocorrência de Chimaerasuchus na China evidencia o intercâmbio faunístico entre o Gondwana e a Ásia Central durante o Cretáceo Inferior.Fil: Fiorelli, Lucas Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina. Universidad Nacional del Comahue. Centro Paleontológico Lago Barreales; ArgentinaFil: Calvo, Jorge. Universidad Nacional del Comahue. Centro Paleontológico Lago Barreales; Argentin

The first “Protosuchian” (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana

El primer “protosuquio” (Archosauria: Crocodyliformes) del Cretácico (Santoniano) de Gondwana. Los restos de “protosuquios” del Cretácico provienen, a excepción del “crocodyliforme de Las Hoyas” del Cretácico Inferior de España, exclusivamente de Asia Central: Zaraasuchus, Gobiosuchus, Zosuchus y Artzosuchus del Cretácico Superior de Mongolia; Tagarosuchus del Cretácico Inferior del sur de Siberia; Edentosuchus, Sichuanosuchus y Shantungosuchus del Cretácico Inferior de China. Aquí reportamos un nuevo taxón de crocodyliforme basal, Neuquensuchus universitas gen.nov., sp.nov., de la provincia de Neuquén, Argentina, correspondiente a la Formación Bajo de la Carpa, representando el primer y único “protosuquio” del Cretácico de Gondwana. Los materiales fragmentarios y articulados corresponden a una especie esbelta y delgada, con extremidades largas y delgadas. Al igual que en Shantungosuchus, los centros cervicales son alargados, con una quilla ventral prominente y parapófisis anteroventrales bien desarrolladas. Como en los crocodyliformes basales, Neuquensuchus posee dos vértebras sacras. Además, una hoja escapular muy expandida, con un puente acromial bien desarrollado y el borde posterior similar a Sichuanosuchus. La cresta deltopectoral pronunciada en el húmero es equivalente a la de Sichuanosuchus y al igual que este, la diáfisis es circular, alargada y delgada con el cóndilo medial mayor que el lateral. Asimismo, las proporciones del radio y la úlna son similares a Sichuanosuchus. Como este, el pubis es alargado, muy delgado en su sección media y poco expandido distalmente. El fémur, tibia y fíbula son alargados y similares a otros crocodyliformes no derivados. Además de representar el primer “protosuquio” cretácico de Gondwana, su presencia fuera de Asia y Europa durante el Cretácico ofrece nueva evidencia de un evento de dispersión pre-Albiano entre Gondwana y Asia Central a través de Europa.The remains of “protosuchians” from the Cretaceous come, to exception of “Las Hoyas crocodyliform” from the Lower Cretaceous of Spain, exclusively of Central Asia: Zaraasuchus, Gobiosuchus, Zosuchus, and Artzosuchus from the Upper Cretaceous of Mongolia; Tagarosuchus from Lower Cretaceous of Southern Siberia; Edentosuchus, Sichuanosuchus, and Shantungosuchus from Lower Cretaceous of China. We report a new basal crocodyliform taxon, Neuquensuchus universitas gen.nov., sp.nov., from Neuquén Province, Argentina, belonging to Bajo de la Carpa Formation, representing the first and only “protosuchian” from the Cretaceous of Gondwana. The articulated and fragmentary materials belonged to a willowy, slender species, with very long and thin extremities. As in Shantungosuchus, the cervical centers are lengthened, with prominent ventral keel and well developed anteroventral parapophyses. As in basal crocodylomorphs, it possesses two sacral vertebrae. Also, a much enlarged scapular blade, with well developed acromial ridge and the posterior edge similar to Sichuanosuchus. The pronounced deltopectoral crest in the complete humerus is equivalent to Sichuanosuchus and as this, a circular, elongated and thin shaft with the medial condyle longer than the lateral one. Also, the complete ulna and radius is similar in their proportions to Sichuanosuchus. As this, the pubis is lengthened, very thin in the half section and not very expanded distally. The femur, tibia and fibula are elongated and similar to other non-derivated crocodyliforms. Besides representing the first Cretaceous “protosuchian” of Gondwana, the occurrence of these outside of Asia and Europe during the Cretaceous offers new evidence of pre-Albian dispersion between Gondwana and Central Asia through Europe.Fil: Fiorelli, Lucas Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Calvo, Jorge Orlando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Centro Paleontológico Lago Barreales; Argentin

High-energy constraints from low-energy neutrino non-standard interactions

Many scenarios of new physics predict the existence of neutrino Non-Standard Interactions, new vector contact interactions between neutrinos and first generation fermions beyond the Standard Model. We obtain model-independent constraints on the Standard Model Effective Field Theory at high energies from bounds on neutrino non-standard interactions derived at low energies. Our analysis explores a large set of new physics scenarios and includes full one-loop running effects below and above the electroweak scale. Our results show that neutrino non-standard interactions already push the scale of new physics beyond the TeV. We also conclude that bounds derived by other experimental probes, in particular by low-energy precision measurements and by charged lepton flavor violation searches, are generally more stringent. Our study constitutes a first step towards the systematization of phenomenological analyses to evaluate the impact of neutrino Non-Standard Interactions for new physics scenarios at high energies.Comment: 25 pages, 7 figures, 2 tables. Merry Christmas and happy new year

"Yo [tampoco] soy marxista". Reflexiones teóricas en torno a la relación entre marxismo y arqueología. "I’m not marxist". Theoretical reflections on the marxism-archaeology relationship

El trabajo es el mediador fundamental de las relaciones sociales en el capitalismo, así como el terreno primordial de la dominación en ese modo de producción. La interpretación propuesta por el «materialismo histórico», según fue formulado por K. Kautsky con unas intenciones políticas muy concretas, convierte este enunciado, en nombre de Marx, en un axioma antropológico. Éste ha sido reproducido, con más o menos exactitud, en el terreno de la arqueología prehistórica. Ante un planteamiento político distinto, centrado en el carácter combativo de la investigación y en el antagonismo e historicidad de las relaciones sociales desde la prehistoria reciente, es posible plantear otra lectura de Marx y de su propuesta sobre la «determinación material» de las formas sociales.Labor is the essential mediator of social relations in capitalism, as well as the primordial ground of domination in that mode of production. The interpretation proposed by «historical materialism», as formulated by K. Kautsky with very specific political purposes, transforms this proposition, in the name of Marx, into an anthropological axiom. This has been reproduced, more or less exactly, in the field of prehistoric archaeology. Adopting a different political approach, focused in the combative character of research and in the antagonism and historicity of social relations since recent prehistory, we may address in a different way Marx and his proposal relating to a «material determination» of social forms

Simulating Extraocular Muscle Dynamics. A Comparison between Dynamic Implicit and Explicit Finite Element Methods

The finite element method has been widely used to investigate the mechanical behavior of biological tissues. When analyzing these particular materials subjected to dynamic requests, time integration algorithms should be considered to incorporate the inertial effects. These algorithms can be classified as implicit or explicit. Although both algorithms have been used in different scenarios, a comparative study of the outcomes of both methods is important to determine the performance of a model used to simulate the active contraction of the skeletal muscle tissue. In this work, dynamic implicit and dynamic explicit solutions are presented for the movement of the eye ball induced by the extraocular muscles. Aspects such as stability, computational time and the influence of mass-scaling for the explicit formulation were assessed using ABAQUS software. Both strategies produced similar results regarding range of movement of the eye ball, total deformation and kinetic energy. Using the implicit dynamic formulation, an important amount of computational time reduction is achieved. Although mass-scaling can reduce the simulation time, the dynamic contraction of the muscle is drastically altered

Práctica arqueológica y política. Un diálogo con Marx a través de la acción local. Archaeological and political practice. A dialogue with Marx through the local action

La práctica arqueológica puede ser definida en un sentido científico y político al mismo tiempo. Esto lo demuestra el esfuerzo de algunos arqueólogos por conocer diversas formas materiales de poder a lo largo de la historia, en aras de una transformación libertaria de las realidades que vivimos. La investigación de esas formas de poder insiste, en el marco del debate marxista, en una perspectiva histórica matizada que contempla la tensión entre identidad y alteridad en las experiencias del poder. La práctica de esa investigación se desarrolla en el seno de las comunidades locales y las problemáticas y resistencias específicas que aparecen en ellas. Se confía en que con ese enfoque la contribución a la transformación sea eficaz.Archaeological practice can be defined scientifically as well as politically, as it emerges from the efforts made by some archaeologists to know different material forms of power through history, with a view to a libertarian transformation of present reality. The investigation of those forms of power focuses, in the context of a Marxist debate, on a qualified historical perspective underlining the existing tension between identity and alterity in power experiences. That investigation is carried out within local communities and taking into account the specific problems and resistances that arise inside them. This approach should contribute, it is hoped, to an effective transformation

Recognition of pen-based music notation with finite-state machines

This work presents a statistical model to recognize pen-based music compositions using stroke recognition algorithms and finite-state machines. The series of strokes received as input is mapped onto a stochastic representation, which is combined with a formal language that describes musical symbols in terms of stroke primitives. Then, a Probabilistic Finite-State Automaton is obtained, which defines probabilities over the set of musical sequences. This model is eventually crossed with a semantic language to avoid sequences that does not make musical sense. Finally, a decoding strategy is applied in order to output a hypothesis about the musical sequence actually written. Comprehensive experimentation with several decoding algorithms, stroke similarity measures and probability density estimators are tested and evaluated following different metrics of interest. Results found have shown the goodness of the proposed model, obtaining competitive performances in all metrics and scenarios considered.This work was supported by the Spanish Ministerio de Educación, Cultura y Deporte through a FPU Fellowship (Ref. AP2012–0939) and the Spanish Ministerio de Economía y Competitividad through the TIMuL Project (No. TIN2013-48152-C2-1-R, supported by UE FEDER funds)