5,630 research outputs found
Double Threefold Degeneracies for Active and Sterile Neutrinos
We explore the possibility that the 3 active (doublet) neutrinos have nearly
degenerate masses which are split only by the usual seesaw mechanism from 3
sterile (singlet) neutrinos in the presence of a softly broken symmetry.
We take the unconventional view that the sterile neutrinos may be light, i.e.
less than 1 keV, and discuss some very interesting and novel phenomenology,
including a connection between the LSND neutrino data and solar neutrino
oscillations.Comment: 8 pages, no figur
Systematic perturbation calculation of integrals with applications to physics
In this paper we generalize and improve a method for calculating the period
of a classical oscillator and other integrals of physical interest, which was
recently developed by some of the authors. We derive analytical expressions
that prove to be more accurate than those commonly found in the literature, and
test the convergence of the series produced by the approach.Comment: 11 pages, 5 figure
Co-evolution of RDF Datasets
Linking Data initiatives have fostered the publication of large number of RDF
datasets in the Linked Open Data (LOD) cloud, as well as the development of
query processing infrastructures to access these data in a federated fashion.
However, different experimental studies have shown that availability of LOD
datasets cannot be always ensured, being RDF data replication required for
envisioning reliable federated query frameworks. Albeit enhancing data
availability, RDF data replication requires synchronization and conflict
resolution when replicas and source datasets are allowed to change data over
time, i.e., co-evolution management needs to be provided to ensure consistency.
In this paper, we tackle the problem of RDF data co-evolution and devise an
approach for conflict resolution during co-evolution of RDF datasets. Our
proposed approach is property-oriented and allows for exploiting semantics
about RDF properties during co-evolution management. The quality of our
approach is empirically evaluated in different scenarios on the DBpedia-live
dataset. Experimental results suggest that proposed proposed techniques have a
positive impact on the quality of data in source datasets and replicas.Comment: 18 pages, 4 figures, Accepted in ICWE, 201
Robust stability analysis of formation control in local frames under time-varying delays and actuator faults
This paper investigates the robust stability of a multiagent system moving to a desired rigid formation in presence of unknown time-varying communication delays and actuator faults. Each agent uses relative position measurements to implement the proposed control method, which does not require common coordinate references. However, the presence of time delays in the measurements, which is inherent to the communication links between agents, has a negative impact in the control system performance leading, in some cases, to instability. Furthermore, the robust stability analysis becomes more complex if failures on actuators are taken into account. In addition, delays may be subject to time variations, depending on network load, availability of communication resources, dynamic routing protocols, or other environmental conditions. To cope with these problems, a sufficient condition based on Linear Matrix Inequalities (LMI) is provided to ensure the robust asymptotic convergence of the agents to the desired formation. This condition is valid for any arbitrarily fast time-varying delays and actuator faults, given a worst-case point-to-point delay. Finally, simulation results show the performance of the proposed approach
Supersymmetric Flavor Models and the B --> phi K_S Anomaly
We consider the flavor structure of supersymmetric theories that can account
for the deviation of the observed time-dependent CP asymmetry in B --> phi K_S
from the standard model prediction. Assuming simple flavor symmetries and
effective field theory, we investigate possible correlations between sizable
supersymmetric contributions to b --> s transitions and to flavor changing
processes that are more tightly constrained. With relatively few assumptions,
we determine the properties of minimal Yukawa and soft mass textures that are
compatible with the desired supersymmetric flavor-changing effect and
constraints. We then present explicit models that are designed (at least
approximately) to realize these textures. In particular, we present an Abelian
model based on a single U(1) factor and a non-trivial extra-dimensional
topography that can explain the CP asymmetry in B --> phi K_S, while
suppressing other supersymmetric flavor changing effects through a high degree
of squark-quark alignment.Comment: 18 pages LaTeX, 3 eps figure
Constraints on Natural MNS Parameters from |U_e3|
The MNS matrix structure emerging as a result of recent neutrino measurements
strongly suggests two large mixing angles (solar and atmospheric) and one small
angle (|U_e3| << 1). Especially when combined with the neutrino mass hierarchy,
these values turn out to impose rather stringent constraints on possible flavor
models connecting the three active fermion generations. Specifically, we show
that an extremely small value of |U_e3| would require fine tuning of Majorana
mass matrix parameters, particularly in the context of seesaw models.Comment: 21 pages, ReVTeX, 2 .eps figure files, updated references and
acknowledgment
STRATEGy Seismic neTwoRk/Array in norThwEstern arGentina: Study of the 2015 El GalpĂłn earthquake and its aftershock sequence
After a damaging, medium-sized earthquake (Mw 5.8; October 17, 2015) in El GalpĂłn area in the Salta Province, we installed a local seismological network around the estimated epicenter covering also remarkable tectonic and geological orographic structures. The 2015 earthquake took place in the Andean foreland at about 17km depth. The so called Santa Bárbara System is the easternmost morphostructural region of the central Andes. As a part of the broken foreland it is bounded to the north by the Subandean Belt and the Sierras Pampeanas lying in the south; to the east joins the Chaco-Paraná basin.Eje: Estudio del Interior Terrestre.Facultad de Ciencias AstronĂłmicas y GeofĂsica
New archaeomagnetic directions from Portugal and evolution of the geomagnetic field in Iberia from Late Bronze Age to Roman Times
This study presents new archaeomagnetic results from 33 combustion structures (kilns and hearths) from the archaeological sites of Castelinho, Crestelos, Olival Poço da Barca and Fonte do Milho in NE Portugal. The age of the investigated structures ranges from 1210 BC to 200 AD according to calibrated radiocarbon dating, thermoluminescence dating and archaeological constraints. Stepwise thermal and alternating field demagnetization isolate a single, stable, characteristic remanence component with very well defined directions. Rock magnetic analyses suggest low-Ti titanomagnetite/maghemite as the main magnetic carrier of the remanence. Mean directions are well grouped in most structures. The effect of thermoremanent anisotropy on mean directions has been evaluated and was found to be important. Inclination increases of between 2° and 13° after applying the anisotropy correction at specimen level. This highlights the requirement of evaluating this effect on the directions of small and flattened thin kilns and hearths. The 31 new directional data improve both the temporal and spatial distribution of the Iberian archaeomagnetic dataset from Late Bronze Age to Roman Times.
Finally, a new directional palaeosecular variation curve for Iberia for the last twelve centuries BC is proposed. The curve has been computed using the bootstrap method and includes data coming from sites within 900 km of Madrid. The new palaeodirectional secular variation curve for Iberia is consistent with the Western European palaeosecular variation curve and with the prediction of regional European models
STRATEGy Seismic neTwoRk/Array in norThwEstern arGentina: Study of the 2015 El GalpĂłn earthquake and its aftershock sequence
After a damaging, medium-sized earthquake (Mw 5.8; October 17, 2015) in El GalpĂłn area in the Salta Province, we installed a local seismological network around the estimated epicenter covering also remarkable tectonic and geological orographic structures. The 2015 earthquake took place in the Andean foreland at about 17km depth. The so called Santa Bárbara System is the easternmost morphostructural region of the central Andes. As a part of the broken foreland it is bounded to the north by the Subandean Belt and the Sierras Pampeanas lying in the south; to the east joins the Chaco-Paraná basin.Eje: Estudio del Interior Terrestre.Facultad de Ciencias AstronĂłmicas y GeofĂsica
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