1,411 research outputs found
Signal estimation and threshold optimization using an array of bithreshold elements
We consider the problem of optimizing signal transmission through
multi-channel noisy devices. We investigate an array of bithreshold noisy
devices which are connected in parallel and convergent on a summing center.
Utilizing the concept of noise-induced linearization we derive an analytical
approximation of the normalized power norm and clarify the relation between the
optimum threshold and the standard deviation of noises. We show that the
optimum threshold value is 0.63 times the standard deviation of the noises.
This relation is applicable to both subthreshold and suprathreshold inputs.Comment: 14 pages, 6 figure
Long term variation of the solar diurnal anisotropy of galactic cosmic rays observed with the Nagoya multi-directional muon detector
We analyze the three dimensional anisotropy of the galactic cosmic ray (GCR)
intensities observed independently with a muon detector at Nagoya in Japan and
neutron monitors over four solar activity cycles. We clearly see the phase of
the free-space diurnal anisotropy shifting toward earlier hours around solar
activity minima in A>0 epochs, due to the reduced anisotropy component parallel
to the mean magnetic field. The average parallel component is consistent with a
rigidity independent spectrum, while the perpendicular component increases with
GCR rigidity. We suggest that this harder spectrum of the perpendicular
component is due to contribution from the drift streaming. We find that the
bidirectional latitudinal density gradient is positive in A>0 epoch, while it
is negative in A<0 epoch, in accord with the drift model prediction. The radial
density gradient, on the other hand, varies with ~11-year cycle with maxima
(minima) in solar maximum (minimum) periods, but there is no significant
difference seen between average radial gradients in A>0 and A<0 epochs. The
average parallel mean free path is larger in A0. We also find,
however, that parallel mean free path (radial gradient) appears to persistently
increase (decreasing) in the last three cycles of weakening solar activity. We
suggest that simple differences between these parameters in A>0 and A<0 epochs
are seriously biased by these long-term trends.Comment: accepted for the publication in the Astrophysical Journa
Are infants in the dark about hidden objects?
Infants appear to search for objects hidden by darkness earlier in development than they search for objects hidden by an occluder in the light. However, these two types of search tasks have differed in numerous ways that may have contributed to better performance in the dark (e.g. in whether the hidden objects made sound, in the number of familiarization trials with visible objects). The current studies controlled such incidental differences between search tasks, so that they could be directly compared. Six-and-a-half-month-olds received four types of test events, in which either a toy or no toy was presented and then hidden in the dark or under a cloth in the light. Infants searched more often on toy than no-toy trials in the dark than with a cloth. The advantage in searching for hidden objects in the dark thus appears to be genuine. Theoretical implications are discussed
Familiarity breeds searching. Infants reverse their novelty preferences when reaching for hidden objects.
What infants appear to know depends heavily on how they are tested. For example, infants seem to understand object permanence (what objects continue to exist when no longer perceptible) within the first few months of life when this understanding is assessed through looking measures, but not until several months later when it is assessed through search measures. One explanation of such results is that infants gradually develop stronger representations of objects through experience, and that stronger representations are required for some tasks than for others. The current study confirms one prediction from this account: Stronger representations of familiar objects (relative to novel objects) should support greater sensitivity to their continued existence. After seeing objects hidden, infants reached more for familiar than novel objects, in striking contrast to their robust novelty preferences with visible objects. Theoretical implications concerning the origins of knowledge are discussed
PCN71 Value of Progression-Free Survival (PFS) in Refractory Non-Small Cell Lung Cancer (NSCLC): An Exploratory Modeling Analysis
Entropy production and fluctuation theorems under feedback control: the molecular refrigerator model revisited
We revisit the model of a Brownian particle in a heat bath submitted to an
actively controlled force proportional to the velocity that leads to thermal
noise reduction (cold damping). We investigate the influence of the continuous
feedback on the fluctuations of the total entropy production and show that the
explicit expression of the detailed fluctuation theorem involves different
dynamics and observables in the forward and backward processes. As an
illustration, we study the analytically solvable case of a harmonic oscillator
and calculate the characteristic function of the entropy production in a
nonequilibrium steady state. We then determine the corresponding large
deviation function which results from an unusual interplay between 'boundary'
and 'bulk' contributions.Comment: 16 pages, 5 figures. References 9,10,13,14,15 added. A few changes in
the text. Accepted for publication in J. Stat. Mec
SOLAR CYCLE DEPENDENCE OF THE DIURNAL ANISOTROPY OF 0.6 TeV COSMIC-RAY INTENSITY OBSERVED WITH THE MATSUSHIRO UNDERGROUND MUON DETECTOR
We analyze the temporal variation of the diurnal anisotropy of sub-TeV cosmic-ray intensity observed with the Matsushiro (Japan) underground muon detector over two full solar activity cycles in 1985-2008. We find an anisotropy component in the solar diurnal anisotropy superimposed on the Compton-Getting anisotropy due to Earth's orbital motion around the Sun. The phase of this additional anisotropy is almost constant at similar to 15:00 local solar time corresponding to the direction perpendicular to the average interplanetary magnetic field at Earth's orbit, while the amplitude varies between a maximum (0.043% +/- 0.002%) and minimum (similar to 0.008% +/- 0.002%) in a clear correlation with the solar activity. We find a significant time lag between the temporal variations of the amplitude and the sunspot number (SSN) and obtain the best correlation coefficient of +0.74 with the SSN delayed for 26 months. We suggest that this anisotropy might be interpreted in terms of the energy change due to the solar-wind-induced electric field expected for galactic cosmic rays (GCRs) crossing the wavy neutral sheet. The average amplitude of the sidereal diurnal variation over the entire period is 0.034% +/- 0.003%, which is roughly one-third of the amplitude reported from air shower and deep-underground muon experiments monitoring multi-TeVGCR intensity suggesting a significant attenuation of the anisotropy due to the solar modulation. We find, on the other hand, only a weak positive correlation between the sidereal diurnal anisotropy and the solar activity cycle in which the amplitude in the "active" solar activity epoch is about twice the amplitude in the "quiet" solar activity epoch. This implies that only one-fourth of the total attenuation varies in correlation with the solar activity cycle and/or the solar magnetic cycle. We finally examine the temporal variation of the "single-band valley depth" (SBVD) quoted by the Milagro experiment and, in contrast with recent Milagro's report, we find no steady increase in the Matsushiro observations in a seven-year period between 2000 and 2007. We suggest, therefore, that the steady increase of the SBVD reported by the Milagro experiment is not caused by the decreasing solar modulation in the declining phase of the 23rd solar activity cycle.ArticleThe Astrophysical Journal. 712(2):1100-1106 (2010)journal articl
- âŠ