49 research outputs found
Do not let the dead bite! : different scenarios of the zombie epidemic reexamined
The Zombie Epidemic is a fun framework for investigating different scenarios of spreading disease. An extended Kermack - McKendrick model is analyzed. The only thing that can save humanity is to not get bitten or to find a remedy for the "zombie virus" (both almost impossible)
In silico study of liquid crystalline phases formed by bent-shaped molecules with excluded volume type interactions
What impact does the mesogens’ shape have on the formation of the liquid crystalline phase? Using Monte Carlo and molecular dynamics simulations we numerically studied a liquid composed of achiral, bent-shaped molecules built of tangent spheres. The system is known to spontaneously break mirror symmetry, as it forms a macroscopically chiral, twist-bend nematic phase [Phys. Rev. Lett. 115, 147801 (2015)]. We examined a full phase diagram by altering the molecules’ curvature along with packing fractions and observed several phases characterized by the orientational and/or translational ordering of molecules. Apart from conventional nematic, smectic A, and the aforementioned twist-bend nematic phase, we identified splay-bend smectic phase. For large densities and strongly curved molecules, another smectic phase emerged, where the polarization vector rotates within a single smectic layer
Studies of new antiferroelectric liquid crystal based on quantum-chemical model
Physical properties of new thermotropic antiferroelectric liquid crystal have been studied. Experiments were done by use of complementary methods such as differential scanning calorimetry, polarizing optical microscopy and X-ray powder diffractometry. Acquired data from X-ray powder diffractometry was examined under application of quantum chemical approach. It has been found that compound studied exhibits stable enantiotropic antiferroelectric SmC_{A}^{*} phase in the wide temperature range while ferroelectric phase SmC^{*} is very narrow
Assessment of dental caries among children and adults inhabiting Starorypin (11th–12th c.) compared to other Early Medieval populations from Poland
Dental caries testing provides information about diet, hygiene and eating habits. This information can be useful in reconstructing the living conditions of historical populations. The aim of this study was to determine the frequency of dental caries in adults and children in the Early Middle Ages population from Starorypin (Poland) and compare the results with other early medieval populations from Poland.A total of 346 adult permanent teeth and 131 deciduous teeth were included in the study. Both the macroscopic method and imaging methods (X-ray and a light-induced fluorescence technique) were applied in the study.Dental caries were recorded in 33% (115/346) of the permanent teeth and in 10% (13/131) of the deciduous teeth. In permanent teeth, dental caries were diagnosed on the approximal surface, while dental caries in deciduous teeth are most often diagnosed on the occlusal surface. Early childhood caries (ECC) were mainly diagnosed on the teeth of individuals within the 3.0–5.5 years age group.The frequency of dental caries seemed to be high compared to other early medieval populations. The obtained results may have been influenced by ‘broadband’ odontological research methods, not limited to the macroscopic method alone. However, it can be also argued that the frequency of dental caries observed in this study might have been influenced by a highly varied diet, as indicated by archaeozoological and archaeobotanical studies. The surfaces affected by dental caries correspond to findings of other studies showing that in adults, these were the approximal surfaces, while they were the labial/occlusion surfaces on the deciduous teeth
Multifractal organization of EEG signals in Multiple Sclerosis
Quantifying the complex/multifractal organization of the brain signals is
crucial to fully understanding the brain processes and structure. In this
contribution, we performed the multifractal analysis of the
electroencephalographic (EEG) data obtained from a controlled multiple
sclerosis (MS) study, focusing on the correlation between the degree of
multifractality, disease duration, and disability level. Our results reveal a
significant correspondence between the complexity of the time series and
multiple sclerosis development, quantified respectively by scaling exponents
and the Expanded Disability Status Scale (EDSS). Namely, for some brain
regions, a well-developed multifractality and little persistence of the time
series were identified in patients with a high level of disability, whereas the
control group and patients with low EDSS were characterised by persistence and
monofractality of the signals. The analysis of the cross-correlations between
EEG signals supported these results, with the most significant differences
identified for patients with EDSS and the combined group of patients with
EDSS and controls. No association between the multifractality and
disease duration was observed, indicating that the multifractal organisation of
the data is a hallmark of developing the disease. The observed
complexity/multifractality of EEG signals is hypothetically a result of
neuronal compensation -- i.e., of optimizing neural processes in the presence
of structural brain degeneration. The presented study is highly relevant due to
the multifractal formalism used to quantify complexity and due to scarce
resting-state EEG evidence for cortical reorganization associated with
compensation.Comment: 39 pages, including supplementary materials (11 figures, 4 tables
Indication and discussion of flaws in "Properties of binary mixtures derived from hydrogen bonded liquid crystals" by M. Fouzai et al. [J. Mol. Liq. 249 (2018) 1279-1286]
This Letter comprises comments, in brief form, about the doubtful results from dielectric spectroscopy measurements and drawbacks in data presentation in the paper by M. Fouzai et al. [J. Mol. Liq. 249 (2018) 1279-1286]
Comments on the published article "The effect of optical purity on the coexistence phenomenon and on the polarization - electric field hysteresis behavior in SmC* and SmC*A phases" by M. Chemingui et al., Journal of Molecular Liquids, 222 (2016) 1101-1108
This letter concerns error in assumed theoretical model and incorrect interpretation and presentation of experimental data in the article by M. Chemingui et al., “The effect of optical purity on the coexistence phenomenon and on the polarization – electric field hysteresis behavior in SmC* and SmC*A phases”, Journal of Molecular Liquids, 222 (2016) 1101–1108
Comment on the published article "Dichroic ratio and order parameters of some sudan dyes doped in nematic liquid crystalline matrix" by A. Maleki et al., Optik, 126 (2015) 5473-5477
This short note concerns the error in the article by A. Maleki et al., "Dichroic ratio and order parameters of some sudan dyes doped in nematic liquid crystalline matrix", Optik, 126 (2015) 5473-5477