40,970 research outputs found
Is it a face of woman or a man? Visual mismatch negativity is sensitive to gender category.
The present study investigated whether gender information for human faces was represented by the predictive mechanism indexed by the visual mismatch negativity (vMMN) event-related brain potential (ERP). While participants performed a continuous size-change-detection task, random sequences of cropped faces were presented in the background, in an oddball setting: either various female faces were presented infrequently among various male faces, or vice versa. In Experiment 1 the inter-stimulus-interval (ISI) was 400 ms, while in Experiment 2 the ISI was 2250 ms. The ISI difference had only a small effect on the P1 component, however the subsequent negativity (N1/N170) was larger and more widely distributed at longer ISI, showing different aspects of stimulus processing. As deviant-minus-standard ERP difference, a parieto-occipital negativity (vMMN) emerged in the 200–500 ms latency range (~350 ms peak latency in both experiments). We argue that regularity of gender on the photographs is automatically registered, and the violation of the gender category is reflected by the vMMN. In conclusion the results can be interpreted as evidence for the automatic activity of a predictive brain mechanism, in case of an ecologically valid category
The integrated Sachs-Wolfe effect in the AvERA cosmology
The recent AvERA cosmological simulation of R\'acz et al. (2017) has a
-like expansion history and removes the tension between
local and Planck (cosmic microwave background) Hubble constants. We contrast
the AvERA prediction of the integrated Sachs--Wolfe (ISW) effect with that of
. The linear ISW effect is proportional to the derivative
of the growth function, thus it is sensitive to small differences in the
expansion histories of the respective models. We create simulated ISW maps
tracing the path of light-rays through the Millennium XXL cosmological
simulation, and perform theoretical calculations of the ISW power spectrum.
AvERA predicts a significantly higher ISW effect than ,
times larger depending on the index of the spherical power
spectrum, which could be utilized to definitively differentiate the models. We
also show that AvERA predicts an opposite-sign ISW effect in the redshift range
, in clear contrast with . Finally,
we compare our ISW predictions with previous observations. While at present
these cannot distinguish between the two models due to large error bars, and
lack of internal consistency suggesting systematics, ISW probes from future
surveys will tightly constrain the models.Comment: 9 pages, 8 figures. Submitted to MNRA
On the evolutionary form of the constraints in electrodynamics
The constraint equations in Maxwell theory are investigated. In analogy with
some recent results on the constraints of general relativity it is shown,
regardless of the signature and dimension of the ambient space, that the
"divergence of a vector field" type constraints can always be put into linear
first order hyperbolic form for which global existence and uniqueness of
solutions to an initial-boundary value problem is guaranteed.Comment: 10 pages, 1 figure; The published version contains several updates of
former one. The introduction is extended, and new sections with an explicit
example and with concluding remarks had also been adde
Caching in Multidimensional Databases
One utilisation of multidimensional databases is the field of On-line
Analytical Processing (OLAP). The applications in this area are designed to
make the analysis of shared multidimensional information fast [9]. On one hand,
speed can be achieved by specially devised data structures and algorithms. On
the other hand, the analytical process is cyclic. In other words, the user of
the OLAP application runs his or her queries one after the other. The output of
the last query may be there (at least partly) in one of the previous results.
Therefore caching also plays an important role in the operation of these
systems. However, caching itself may not be enough to ensure acceptable
performance. Size does matter: The more memory is available, the more we gain
by loading and keeping information in there. Oftentimes, the cache size is
fixed. This limits the performance of the multidimensional database, as well,
unless we compress the data in order to move a greater proportion of them into
the memory. Caching combined with proper compression methods promise further
performance improvements. In this paper, we investigate how caching influences
the speed of OLAP systems. Different physical representations (multidimensional
and table) are evaluated. For the thorough comparison, models are proposed. We
draw conclusions based on these models, and the conclusions are verified with
empirical data.Comment: 14 pages, 5 figures, 8 tables. Paper presented at the Fifth
Conference of PhD Students in Computer Science, Szeged, Hungary, 27 - 30 June
2006. For further details, please refer to
http://www.inf.u-szeged.hu/~szepkuti/papers.html#cachin
- …