614 research outputs found
Improved bounds on heavy quark electric dipole moments
New bounds on the electric dipole moment (EDM) of charm and bottom quarks are
derived using the stringent limits on their chromo-EDMs. The new limits,
and , improve the previous ones by about three orders of
magnitude. These indirect bounds have implications for different models of new
physics, including two-Higgs-doublet, leptoquarks, and supersymmetry models.Comment: 5 pages, 4 figure
A fast and light stream cipher for smartphones
We present a stream cipher based on a chaotic dynamical system. Using a
chaotic trajectory sampled under certain rules in order to avoid any attempt to
reconstruct the original one, we create a binary pseudo-random keystream that
can only be exactly reproduced by someone that has fully knowledge of the
communication system parameters formed by a transmitter and a receiver and
sharing the same initial conditions. The plaintext is XORed with the keystream
creating the ciphertext, the encrypted message. This keystream passes the NISTs
randomness test and has been implemented in a videoconference App for
smartphones, in order to show the fast and light nature of the proposed
encryption system
Phonological prediction in speech processing
Auditory speech perception can be described as the task of mapping an auditory
signal into meaning. We routinely perform this task in an automatic and effortless
manner, which might conceal the complexity behind this process. It should be
noted that the speech signal is highly variable, ambiguous and usually perceived in
noise. One possible strategy the brain might use to handle this task is to generate
predictions about the incoming auditory stream.
Prediction occupies a prominent role in cognitive functions ranging from perception
to motor control. In the specific case of speech perception, evidence shows
that listeners are able to make predictions about incoming speech stimuli. Word
processing, for example, is facilitated by the context of a sentence. Furthermore,
electroencephalography studies have shown neural correlates that behave like error
signals triggered when an unexpected word is encountered.
But these examples of prediction in speech processing occur between words, and
rely on semantic and or syntactic knowledge. Given the salient role of prediction
in other cognitive domains, we hypothesize that prediction might serve a role in
speech processing, even at the phonological level (within words) and independently
from higher level information such as syntax or semantics. In other words, the brain
might use the first phonemes of a word to anticipate which should be the following
ones.
To test this hypothesis, we performed three electroencephalography experiments
with an oddball design. This approach allowed us to present individual words in
a context that does not contain neither semantic nor syntactic information. Additionally,
this type of experimental design is optimal for the elicitation of event
related potentials that are well established marker of prediction violation, such as
the Mismatch Negativity (MMN) and P3b responses.
In these experiments, participants heard repetitions of standard words, among
which, deviant words were presented infrequently. Importantly, deviant words were
composed by the same syllables as standard words, although in different combinations.
For example if in an experiment XXX and YYY were two standard words,
XXY could be a deviant word. We expected that if as we proposed, the first
phonemes of a word are used to predict which should be the following ones, encountering
a deviant of this kind would elicit a prediction error signal.
In Chapter 3, we establish that as we expected, the presentation of deviant
words, composed of an unexpected sequence of phonemes, generates a chain of well
established prediction error signals, which we take as evidence of the prediction of
the forthcoming phonemes of a word. Furthermore, we show that the amplitude of
these error signals can be modulated by the amount of congruent syllables presented
before the point of deviance, which suggests that prediction strength can increase
within a word as previous predictions prove to be successful.
In Chapter 4, we study the modulating role of attentional set on the chain
of prediction error signals. In particular we show that while high level prediction
(indexed by the P3b response) is strategically used depending on the task at hand,
early prediction error signals such as the MMN response are generated automatically,
even when participants are simply instructed to listen to all the words. These results
imply that phonological predictions are automatically deployed while listening to
words, regardless of the task at hand.
In Chapter 5, we extend our results to a more complex stimulus set that resemble
natural speech more closely. Furthermore we show that the amplitude of the
MMN and P3b prediction error signals is correlated with participant's reaction time
in an on-line deviant detection task. This provides a strong argument in favor of a
functional role of phonological predictions in speech processing.
Taken together, this work shows that phonological predictions can be generated
even in the absence higher level information such as syntax and semantics. This
might help the human brain to complete the challenging task of mapping such a
variable and noisy signal as speech, into meaning, in real time
Battle of oral anticoagulants in the field of atrial fibrillation scrutinized from a clinical practice (the real world) perspective
Warfarin has a long history of benefit and has become the gold standard medication for the prevention of ischemic stroke in patients with atrial fibrillation. Nevertheless, it is far from perfect and there is no doubt that new drugs must be found to replace warfarin. The new oral anticoagulants that are on the market or awaiting approval or under research offer some benefits but not enough to replace warfarin until results of additional studies can show an adequate balance between effectiveness/safety and cost/benefit. There are several issues concerning the new oral anticoagulants. It is essential that the effect of any anticoagulant can be measured in plasma. But to date, there is no test to assess the effect or therapeutic range for the new oral anticoagulants. There is no antidote to neutralize the action of the new drugs in cases of bleeding or when acute surgical intervention is necessary. Dabigatran requires dose adjustment in patients with moderate renal impairment and is contraindicated in patients with severe renal failure. Rivaroxaban should be used with caution in patients with severe renal impairment. Apixaban excretion is also partly dependent on renal function, although the impact of renal insufficiency has not yet been determined. How anticoagulant bridging can be done before surgery has not yet been established. In conclusion, although thousands of patients have been treated in phase III studies, additional data are necessary before conclusions can be drawn on the potential for these new anticoagulant drugs to replace warfarin in patients with atrial fibrillation
Una propuesta multimétodo para un abordaje transaccional del espacio público en la escala de barrio
La perspectiva transaccional resulta muy atractiva para analizar y actuar sobre el espacio público en la escala de barrio. Sin embargo, las diferencias metodológicas y de lenguaje entre las distintas disciplinas implicadas lo hacen bastante complejo. En este artÃculo se presenta una estrategia cualitativa de análisis multimétodo, como una propuesta que integra los diferentes lenguajes gráficos y textuales que dominan en los análisis unidisciplinares del espacio público, a través de un trabajo de espacialización gráfica de resultados. Se triangularon diversas técnicas y se sometieron a un mismo proceso analÃtico (Grounded Theory), lo que apoyado por los programas de procesamiento Atlas/ti y Arcgis hicieron posible ligar aspectos gráficos (mapas e imágenes) con observaciones de los investigadores y narraciones biográficas de los participantes, asociando de esta manera, espacios fÃsicos concretos con la evolución y construcción de significados y usos espaciales.The transactional perspective is very attractive in order to analyze and intervene in public space on neighborhood scale. However, language and methodological differences between the various disciplines involved make it quite complex. In this article we present a multi-method qualitative strategy of analysis, integrating various results graphically, in an attempt to bring together the graphic and textual languages that dominate single-discipline approaches of public space. Diverse techniques were triangulated and underwent the same analytical process (Grounded Theory), supported by Atlas / ti and Arcgis software. Using this techniques it was possible to link graphic aspects (maps and images) with comments from researchers and biographical accounts of the participants. So, specific physical spaces were associated with the development and construction of spatial meanings and uses
A multi-method proposal to study the public space in the scale of neighborhood from a transactional approach
La perspectiva transaccional resulta muy atractiva para analizar y actuar sobre el espacio público en la escala de barrio. Sin embargo, las diferencias metodológicas y de lenguaje entre las distintas disciplinas implicadas lo hacen bastante complejo. En este artÃculo se presenta una estrategia cualitativa de análisis multimétodo, como una propuesta que integra los diferentes lenguajes gráficos y textuales que dominan en los análisis unidisciplinares del espacio público, a través de un trabajo de espacialización gráfica de resultados. Se triangularon diversas técnicas y se sometieron a un mismo proceso analÃtico (Grounded Theory), lo que apoyado por los programas de procesamiento Atlas/ti y Arcgis hicieron posible ligar aspectos gráficos (mapas e imágenes) con observaciones de los investigadores y narraciones biográficas de los participantes, asociando de esta manera, espacios fÃsicos concretos con la evolución y construcción de significados y usos espaciales.The transactional perspective is very attractive in order to analyze and intervene in public space on neighborhood scale. However, language and methodological differences between the various disciplines involved make it quite complex. In this article we present a multi-method qualitative strategy of analysis, integrating various results graphically, in an attempt to bring together the graphic and textual languages that dominate single-discipline approaches of public space. Diverse techniques were triangulated and underwent the same analytical process (Grounded Theory), supported by Atlas / ti and Arcgis software. Using this techniques it was possible to link graphic aspects (maps and images) with comments from researchers and biographical accounts of the participants. So, specific physical spaces were associated with the development and construction of spatial meanings and uses
Dynamics of two coupled chaotic systems driven by external signals
Setting-up a controlled or synchronized state in a space-time chaotic structure targeting an unstable periodic orbit is a key feature of many problems in high dimensional physical, electronics,
biological and ecological systems (among others). Formerly, we have shown numerically and experimentally that phase synchronization [M.G. Rosenblum, A.S. Pikovsky, J. Kurths, Phys. Rev. Lett. 78, 4193 (1997)] can be achieved in time dependent hydrodynamic flows [D. Maza, A. Vallone, H.L. Mancini, S. Boccaletti, Phys. Rev. Lett. 85, 5567 (2000)]. In that case the flow was generated in a small container
with inhomogeneous heating in order to have a single roll structure produced by a B´enard-Marangoni instability [E.L. Koshmieder, B´enard Cells and Taylor Vortices (Cambridge University Press, 1993)]. Phase
synchronization was achieved by a small amplitude signal injected at a subharmonic frequency obtained from the measured Fourier temperature spectrum. In this work, we analyze numerically the effects of driving
two previously synchronized chaotic oscillators by an external signal. The numerical system represents a convective experiment in a small container with square symmetry, where boundary layer instabilities are coupled by a common flow. This work is an attempt to control this situation and overcome some difficulties to select useful frequency values for the driving force, analyzing the influence of different harmonic injection signals on the synchronization in a system composed by two identical chaotic Takens-Bogdanov equations
(TBA and TBB) bidirectionally coupled
Complexity control in a synchronized complex system
We numerically analyze the problem of how to drive a synchronized state in a complex system to other state with diferent complexity, keeping synchronization. The complex system used is obtained by synchronizing two identical chaotic Takens-Bogdanov sub-systems specially coupled to recover in the global system the symmetries of each oscillator. The global state is adjusted to have an initial synchronized hyperchaotic state (with two positive Lyapunov exponents). This work is an attempt, using small amplitude external signals, to drive the global system to other complex state keeping the synchronized state. The method used to overcome the problems that we had to select a useful frequency value for the driving signal will be discussed, together with a possible experiment in a thermo-convective flow for validating the results obtained
Gestión deportiva y desempeño docente en profesores de dos instituciones educativas públicas de Arequipa, 2023
La investigación se propuso como objetivo determinar la influencia de la gestión
deportiva en el desempeño docente en profesores de dos instituciones públicas
de Arequipa, 2023. El tipo de investigación fue básica de nivel explicativo, de
enfoque cuantitativo; de diseño no experimental, corte transversal – correlacional
causal. Por ello se contó con una población de 60 docentes de la institución
educativa. Por lo tanto, una muestra 52 docentes y el muestreo probabilÃstico
aleatoria simple. La técnica empleada para el recojo de información fue la
encuesta y como instrumento se utilizó dos cuestionarios validados a través de
juicio de expertos y estableciendo su confiabilidad a través del estadÃstico Alfa
de Cronbach que demuestra fuerte y alta confiabilidad. Como conclusión se
demostró, según el coeficiente de Nagelkerke, se evidencia que el desempeño
docente depende al 35.9% de la gestión deportiva. Concluyó que existe
influencia de la gestión deportiva en el desempeño docente en profesores de dos
instituciones públicas, Arequipa, 2023
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