233 research outputs found
Three Applications to Rational Relations of the High Undecidability of the Infinite Post Correspondence Problem in a Regular omega-Language
It was noticed by Harel in [Har86] that "one can define -complete
versions of the well-known Post Correspondence Problem". We first give a
complete proof of this result, showing that the infinite Post Correspondence
Problem in a regular -language is -complete, hence located
beyond the arithmetical hierarchy and highly undecidable. We infer from this
result that it is -complete to determine whether two given infinitary
rational relations are disjoint. Then we prove that there is an amazing gap
between two decision problems about -rational functions realized by
finite state B\"uchi transducers. Indeed Prieur proved in [Pri01, Pri02] that
it is decidable whether a given -rational function is continuous, while
we show here that it is -complete to determine whether a given
-rational function has at least one point of continuity. Next we prove
that it is -complete to determine whether the continuity set of a
given -rational function is -regular. This gives the exact
complexity of two problems which were shown to be undecidable in [CFS08].Comment: To appear in: Special Issue: Frontier Between Decidability and
Undecidability and Related Problems, International Journal of Foundations of
Computer Scienc
A Survey on Continuous Time Computations
We provide an overview of theories of continuous time computation. These
theories allow us to understand both the hardness of questions related to
continuous time dynamical systems and the computational power of continuous
time analog models. We survey the existing models, summarizing results, and
point to relevant references in the literature
Geographic origin as a determinant of left ventricular mass and diastolic function - the Cardiovascular Risk in Young Finns Study
Aims: Eastern Finns have higher risk of coronary heart disease (CHD) and carotid intima-media thickness than western Finns although current differences in CHD risk factors are minimal. Left ventricular (LV) mass and diastolic function predict future cardiovascular events but their east-west differences are unknown. We examined the association of eastern/western baseline origin with LV mass and diastolic function. Methods : The study population included 2045 subjects of the Cardiovascular Risk in Young Finns Study with data from the baseline survey (1980) and the latest follow-up (2011) when echocardiography was performed at the age of 34-49 years. Results: Subjects with eastern baseline origin had in 2011 higher LV mass (139 +/- 1.0 vs. 135 +/- 1.0 g, p=0.006) and E/e-ratio indicating weaker LV diastolic function (4.86 +/- 0.03 vs. 4.74 +/- 0.03, p=0.02) than western subjects. Results were independent of age, sex, area of examination and CHD risk factors such as blood pressure and BMI (LV mass indexed with height: pPeer reviewe
Solving analytic differential equations in polynomial time over unbounded domains
In this paper we consider the computational complexity of solving initial-value problems de ned with analytic ordinary diferential
equations (ODEs) over unbounded domains of Rn and Cn, under the Computable Analysis setting. We show that the solution can be computed in polynomial time over its maximal interval of de nition, provided it satis es a very generous bound on its growth, and that the function admits an analytic extension to the complex plane
A Dip Into a Deep Well: Online Political Advertisements, Valence, and European Electoral Campaigning
Online political advertisements have become an important element in electoral
campaigning throughout the world. At the same time, concepts such as
disinformation and manipulation have emerged as a global concern. Although
these concepts are distinct from online political ads and data-driven electoral
campaigning, they tend to share a similar trait related to valence, the
intrinsic attractiveness or averseness of a message. Given this background, the
paper examines online political ads by using a dataset collected from Google's
transparency reports. The examination is framed to the mid-2019 situation in
Europe, including the European Parliament elections in particular. According to
the results based on sentiment analysis of the textual ads displayed via
Google's advertisement machinery, (i) most of the political ads have expressed
positive sentiments, although these vary greatly between (ii) European
countries as well as across (iii) European political parties. In addition to
these results, the paper contributes to the timely discussion about data-driven
electoral campaigning and its relation to politics and democracy
Increased Energy Expenditure, Lipolysis and Hyperinsulinemia Confer Resistance to Central Obesity and Type 2 Diabetes in Mice Lacking Alpha2α-Adrenoceptors
The α2A-adrenoceptors (ARs) are Gi-coupled receptors, which prejunctionally inhibit the release of norepinephrine (NE) and epinephrine (Epi), and postjunctionally insulin secretion and lipolysis. We have earlier shown that α2A-/- mice display sympathetic hyperactivity, hyperinsulinemia and improved glucose tolerance. Here we employed α2A-/- mice and placed the mice on a high-fat diet (HFD) to test the hypothesis that lack of α2A-ARs protects from diet-induced obesity (DIO) and type 2 diabetes (T2D). In addition, high caloric diet was combined with running wheel exercise to test the interaction of diet and exercise. HFD was obesogenic in both genotypes, but α2A-/- mice accumulated less visceral fat than their WT controls, were protected from T2D, and their insulin secretion was unaltered by the diet. Lack of α2A-ARs associated with increased sympatho-adrenal tone, which resulted in increased energy expenditure and fat oxidation rate potentiated by HFD. Fittingly, α2A-/- mice displayed enhanced lipolytic responses to Epi, and increased fecal lipids suggesting altered fat mobilization and absorption. Subcutaneous white fat appeared to be thermogenically more active (measured as Ucp1 mRNA expression) in α2A-/- mice, and brown fat showed an increased response to norepinephrine. Exercise was effective in reducing total body adiposity and increasing lean mass in both genotypes, but there was a significant diet-genotype interaction, as even modestly increased physical activity combined with lack of α2A-AR signalling promoted weight loss more efficiently than exercise with normal α2A-AR function. These results suggest that blockade of α2A-ARs may be exploited to reduce visceral fat and to improve insulin secretion.
Effect of Contour Shape of Nervous System Electromagnetic Stimulation Coils on the Induced Electrical Field Distribution
BACKGROUND: Electromagnetic stimulation of the nervous system has the advantage of reduced discomfort in activating nerves. For brain structures stimulation, it has become a clinically accepted modality. Coil designs usually consider factors such as optimization of induced power, focussing, field shape etc. In this study we are attempting to find the effect of the coil contour shape on the electrical field distribution for magnetic stimulation. METHOD AND RESULTS: We use the maximum of the induced electric field stimulation in the region of interest as the optimization criterion. This choice required the application of the calculus of variation, with the contour perimeter taken as a pre-set condition. Four types of coils are studied and compared: circular, square, triangular and an 'optimally' shaped contour. The latter yields higher values of the induced electrical field in depths up to about 30 mm, but for depths around 100 mm, the circular shape has a slight advantage. The validity of the model results was checked by experimental measurements in a tank with saline solution, where differences of about 12% were found. In view the accuracy limitations of the computational and measurement methods used, such differences are considered acceptable. CONCLUSION: We applied an optimization approach, using the calculus of variation, which allows to obtain a coil contour shape corresponding to a selected criterion. In this case, the optimal contour showed higher intensities for a longer line along the depth-axis. The method allows modifying the induced field structure and focussing the field to a selected zone or line
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