1,466 research outputs found
Spin-dependent effective interactions for halo nuclei
We discuss the spin-dependence of the effective two-body interactions
appropriate for three-body computations. The only reasonable choice seems to be
the fine and hyperfine interactions known for atomic electrons interacting with
the nucleus. One exception is the nucleon-nucleon interaction imposing a
different type of symmetry. We use the two-neutron halo nucleus 11Li as
illustration. We demonstrate that models with the wrong spin-dependence are
basically without predictive power. The Pauli forbidden core and valence states
must be consistently treated.Comment: TeX file, 6 pages, 3 postscript figure
Modeling Nonequilibrium Phase Transitions and Critical Behavior in Complex Systems
We comment on some recent, yet unpublished results concerning instabilities
in complex systems and their applications. In particular, we briefly describe
main observations during extensive computer simulations of two lattice
nonequilibrium models. One exhibits robust and efficient processes of pattern
recognition under synaptic coherent activity; the second example exhibits
interesting critical behavior and simulates nucleation and spinodal
decomposition processes in driven fluids.Comment: 6 pages, 4 figure
A new ornithopod dinosaur from the Santonian of Northern Patagonia (Rincón de los Sauces, Argentina)
In recent decades, the Argentinian ornithopod record – which includes eight species that have been described – has increased as a result of the discovery of diverse new bone remains from the Upper Cretaceous. The area near the town of Rincón de los Sauces (Neuquén Province) presents rich fossiliferous outcrops that have provided new ornithopod remains. These bones are from two units: the Plottier and Bajo de la Carpa formations. In the latter, several isolated postcranial bones and a partial articulated skeleton (MAU-Pv-CO-596) have been found. The holotype of Mahuidacursor lipanglef gen. et sp. nov. (MAU-Pv-CO-596) comes from the Cerro Overo site (Santonian, Upper Cretaceous). The skeleton preserves elements from the cervical and dorsal series, the pectoral girdle and the right forelimb. It corresponds to a medium-bodied ornithopod with a gracile general appearance. Histological analysis suggests that the specimen was a sexually mature but not fully grown individual. Some distinctive characters present in Mahuidacursor, such as the strongly bowed humeral shaft and the weakly developed deltopectoral crest, are shared with other South American basal ornithopods. A phylogenetic analysis including Mahuidacursor within a large ornithischian dataset was performed. The results show Mahuidacursor to be a basal ornithopod recovered within a polytomy along with Notohypsilophodon and the clade Elasmaria (Talenkauen + Macrogryphosaurus)
Cinemática rotacional del cabalgamiento basal surpirenaico en las Sierras Exteriores Aragonesas: Datos magnetotectónicos
The magnetotectonic analysis of 32 sites located along the External Sierras (mainly in Middle Eocene marls) shows the primary character of the magnetisation and pennits the differences between the paleovectors obtained to be interpreted as a result of the rotational kinematics of the southpyrenean floor thrust in the study area. The constancy of the directions of the defined unblocking intervals (300"-425°C for the thermal treatment) and the homogeneity of the magnetic carriers (these were always low coercitivity phases, probably sulphides andlor magnetite) prove the stability of the magnetisation. On the other hand, the primary character of the magnetisation (Middle Eocene) can be demonstrated by: a) the constancy of the magnetic inclination (47.3 +/- 1.7) and its similarity with the reference direction; b) the occurrence of reversals, and the positive result of the fold-test made in the Pico del Águila anticline; c) the consistency between the reference direction (DEC = 005", INC = 51°, a95=6 ") and the direction obtained for the authocthonous footwall (DEC = 005", INC = 38", a95= 8") which crops out in the western sector of the Sierras Exteriores thrust front. The interpretation of the paleomagnetic data within the External Sierras structural framework clearly shows that the kinematics of individual thrust sheets involves a clockwise component, at least during a period of their evolution. The maximum rotation values were found in the western and central sectors (42" and 30" respectively). The age of the rotation decreases towards the west along with the age of deformation of the cover rocks. Starting in late Priabonian the kinematics of the thrust front resulted in a lack of rotation in the central sector of the Sierras, while the western sector undenvent a clockwise rotation. The differential movement between both sectors gave rise to the development or reactivation of structures (i. e. Rasal-Anzáñigo anticlines) that articulated the deformation of adjacent zones with different rotational components
Relativistic description of 3He(e,e'p)2H
The Relativistic Distorted-Wave Impulse Approximation is used to describe the
He()H process. We describe the He nucleus within the
adiabatic hyperspherical expansion method with realistic nucleon-nucleon
interactions. The overlap between the He and the deuteron wave functions
can be accurately computed from a three-body calculation. The nucleons are
described by solutions of the Dirac equation with scalar and vector (S-V)
potentials. The wave function of the outgoing proton is obtained by solving the
Dirac equation with a S-V optical potential fitted to elastic proton scattering
data on the residual nucleus. Within this theoretical framework, we compute the
cross section of the reaction and other observables like the
transverse-longitudinal asymmetry, and compare them with the available
experimental data measured at JLab.Comment: 4 pages, 3 figures. Proceedings of the 21st European Few Body
Conference held in Salamanca (Spain) in August-September 201
Performance Evaluation of Single-Channel Receivers for Wireless Optical Communications by Numerical Simulations
Tagging and recapture activities carried out by the Spanish Confederation of Responsible Recreational fishing (ceprr) with the Scientific Coordination of the Spanish Institute of Oceanography (IEO) in the Mediterranean (2008-2011)
During the 2008-2011 period, 1548 specimens of tuna and tuna-like species were tagged by the
Spanish Confederation of Responsible Recreational Fishing (CEPRR) with the scientific
coordination of the Spanish Institute of Oceanography (IEO). Of these, 1031 bluefin tuna were
tagged with conventional tags, whereas 10 other specimens of the same species were tagged
with pop-up satellite electronic tags in the Mediterranean. Five pop-up electronic tags
remained on the adult specimens up to 110 days. In this period, the specimens stayed in the
tagging area except for one of them, which reached Algerian waters in the winter. Similarly,
333 long-finned tuna and up to 184 specimens belonging to other species such as swordfish,
little tunny, bonito, frigate tuna and spearfish, were also tagged. Eight bluefin tuna were
recaptured, including one adult tuna which was found in the same area where it was tagged
(Balearic Islands) 1343 days after release. A juvenile tuna tagged in the Mediterranean was
recaptured more than two years after release in the Cantabrian Sea. Over the 2008-2011
period, the IEO provided a number of training courses on conventional and electronic tagging
techniques at the different ports where tournaments and/or tagging and release campaigns
were carried out. This promoted participation of the CEPRR in the tagging design of the
GBYP-ICCAT Atlantic-wide Research Programme on Bluefin Tuna, as well as strategic and
scientific interest.Postprin
A Fuzzy k-Nearest Neighbors Classifier to Deal with Imperfect Data
© 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This document is the Accepted version of a Published Work that appeared in final form in Soft Computing. To access the final edited and published work see https://doi.org/10.1007/s00500-017-2567-xThe k-nearest neighbors method (kNN) is a nonparametric, instance-based method used for regression and
classification. To classify a new instance, the kNN method computes its k nearest neighbors and generates a class value from them. Usually, this method requires that the information available in the datasets be precise and accurate, except for the existence of missing values. However, data imperfection is inevitable when dealing with real-world scenarios. In this paper, we present the kNNimp classifier, a k-nearest neighbors method to perform classification from datasets with imperfect value. The importance of each neighbor in the output decision is based on relative distance and its degree of imperfection. Furthermore, by using external parameters, the classifier enables us to define the maximum allowed imperfection, and to decide if the final output could be derived solely from the greatest weight class (the best class) or from the best class and a weighted combination of the closest classes to the best one. To test the proposed method, we performed several experiments with both synthetic and realworld datasets with imperfect data. The results, validated through statistical tests, show that the kNNimp classifier is robust when working with imperfect data and maintains a
good performance when compared with other methods in the literature, applied to datasets with or without imperfection
High quality InAlN single layers lattice-matched to GaN grown by molecular beam epitaxy
We report on properties of high quality ~60 nm thick InAlN layers nearly in-plane lattice-matched to GaN, grown on c-plane GaN-on-sapphire templates by plasma-assisted molecular beam epitaxy. Excellent crystalline quality and low surface roughness are confirmed by X-ray diffraction, transmission electron microscopy, and atomic force microscopy. High annular dark field observations reveal a periodic in-plane indium content variation (8 nm period), whereas optical measurements evidence certain residual absorption below the band-gap. The indium fluctuation is estimated to be +/- 1.2% around the nominal 17% indium content via plasmon energy oscillations assessed by electron energy loss spectroscopy with sub-nanometric spatial resolution
A new primitive Neornithischian dinosaur from the Jurassic of Patagonia with gut contents
We describe a new species of an ornithischian dinosaur, Isaberrysaura mollensis gen. et sp. nov. The specimen, consisting in an almost complete skull and incomplete postcranium was collected from the marine-deltaic deposits of the Los Molles Formation (Toarcian-Bajocian), being the first reported dinosaur for this unit, one of the oldest from Neuquén Basin, and the first neornithischian dinosaur known from the Jurassic of South America. Despite showing a general stegosaurian appearance, the extensive phylogenetic analysis carried out depicts Isaberrysaura mollensis gen. et sp. nov. as a basal ornithopod, suggesting that both Thyreophora and neornithischians could have achieved significant convergent features. The specimen was preserved articulated and with some of its gut content place in the middle-posterior part of the thoracic cavity. Such stomach content was identified as seeds, most of them belonging to the Cycadales group. This finding reveals a possible and unexpected role of this ornithischian species as seed-dispersal agent
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