random fields
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BACKGROUND AND OBJECTIVE: Capturing the population variability of bone properties is of paramount importance to biomedical engineering. The aim of the present paper is to describe variability and correlations in bone mineral density with a spatial random field inferred from routine computed tomography data. METHODS: Random fields were simulated by transforming pairwise uncorrelated Gaussian random variables into correlated variables through the spectral decomposition of an age-detrended correlation matrix. The validity of the random field model was demonstrated in the spatiotemporal analysis of bone mineral density. The similarity between the computed tomography samples and those generated via random fields was analyzed with the energy distance metric. RESULTS: The random field of bone mineral density was found to be approximately Gaussian/slightly left-skewed/strongly right-skewed at various locations. However, average bone density could be simulated well with the proposed Gaussian random field for which the energy distance, i.e., a measure that quantifies discrepancies between two distribution functions, is convergent with respect to the number of correlation eigenpairs. CONCLUSIONS: The proposed random field model allows the enhancement of computational biomechanical models with variability in bone mineral density, which could increase the usability of the model and provides a step forward in in-silico medicine.
- MeSH
- kosti a kostní tkáň * MeSH
- kostní denzita * MeSH
- počítačová rentgenová tomografie MeSH
- Publikační typ
- časopisecké články MeSH
Cell phones and other communication devices have become the primary source of socialization, especially among adolescents. The aim of the study was to assess the levels of radiated radiofrequency (RF) power (1788.5 MHz, max. 30 V/m) around the head of adolescents. The measurements were performed in 2016 at the Department of Medical Biophysics of Jessenius Faculty of Medicine in Martin. The sample group consisted of 44 adolescents of Viliam Pauliny-Toth, Grammar School in Martin. To measure the performance levels of electromagnetic fields (EMF), we used selective radiation meter NARDA SRM 3006 (9 kHz–6 GHz) with the function of a spectrum analyzer. The average values of power were recorded in eight positions around the head with six minutes exposure length of each of them. Every adolescent filled out a short questionnaire on personal perception of the effects of RF radiation on the body after the exposure. The statistical evaluation showed a significant decrease in the intensity of power on the left side of the adolescent’s head compared to the right side (p < 0.01–0.001), which confirmed different degrees of absorption by the head tissues. The highest level of absorption was measured at temporal area of the head connecting both ears. Shortterm exposure to RF radiation did not cause strong adverse health effects in adolescents, however in a few cases tachycardia, drowsiness, headache, fatigue and restlessness appeared. It is necessary to pay more attention to the examination of the relationship between exposure to RF EMF and the potential adverse health reactions mainly in adolescents.
- MeSH
- elektromagnetická pole * škodlivé účinky MeSH
- hlava účinky záření MeSH
- lidé MeSH
- mladiství MeSH
- mobilní telefon MeSH
- průzkumy a dotazníky MeSH
- rádiové vlny klasifikace škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- práce podpořená grantem MeSH
Microtubules are electrically polar structures fulfilling prerequisites for generation of oscillatory electric field in the kHz to GHz region. Energy supply for excitation of elasto-electrical vibrations in microtubules may be provided from GTP-hydrolysis; motor protein-microtubule interactions; and energy efflux from mitochondria. We calculated electric field generated by axial longitudinal vibration modes of microtubules for random, and coherent excitation. In case of coherent excitation of vibrations, the electric field intensity is highest at the end of microtubule. The dielectrophoretic force exerted by electric field on the surrounding molecules will influence the kinetics of microtubule polymerization via change in the probability of the transport of charge and mass particles. The electric field generated by vibrations of electrically polar cellular structures is expected to play an important role in biological self-organization.
- MeSH
- biologické hodiny fyziologie MeSH
- elektromagnetická pole MeSH
- eukaryotické buňky fyziologie MeSH
- mikrotubuly fyziologie MeSH
- náhodné rozdělení MeSH
- polarita buněk fyziologie MeSH
- sušené kvasnice MeSH
- vibrace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- MeSH
- alergie diagnóza krev moč MeSH
- elektrokardiografie metody MeSH
- elektromagnetická pole škodlivé účinky MeSH
- krevní tlak MeSH
- leukocyty MeSH
- lidé MeSH
- melatonin analogy a deriváty moč MeSH
- nemoc vyvolaná prostředím diagnóza krev moč MeSH
- průzkumy a dotazníky MeSH
- Check Tag
- lidé MeSH
- Geografické názvy
- Itálie MeSH
Using random chemical mutagenesis we obtained the mutant of Cupriavidus necator H16 which was capable of improved (about 35 %) production of poly(3-hydroxybuytrate) (PHB) compared to the wild-type strain. The mutant exhibited significantly enhanced specific activities of enzymes involved in oxidative stress response such as malic enzyme, NADP-dependent isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase and glutamate dehydrogenase. Probably, due to the activation of these enzymes, we also observed an increase of NADPH/NADP⁺ ratio. It is likely that as a side effect of the increase of NADPH/NADP⁺ ratio the activity of PHB biosynthetic pathway was enhanced, which supported the accumulation of PHB. Furthermore, the mutant was also able to incorporate propionate into copolymer poly(3-hydroxybuytyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] more efficiently than the wild-type strain (Y3HV/prec = 0.17 and 0.29 for the wild-type strain and the mutant, respectively)). We assume that it may be caused by lower availability of oxaloacetate for the utilization of propionyl-CoA in 2-methylcitrate cycle due to increased action of malic enzyme. Therefore, propionyl-CoA was incorporated into copolymer rather than transformed to pyruvate via 2-methylcitrate cycle. Thus, the mutant was capable of the utilization of waste frying oils and the production of P(3HB-co-3HV) with better yields and improved content of 3HV resulting in better mechanical properties of copolymer than the wild-type strain. The results of this work may be used for the development of innovative fermentation strategies for the production of PHA and also it might help to define novel targets for the genetic manipulations of PHA producing bacteria.
- MeSH
- acylkoenzym A metabolismus MeSH
- bakteriální proteiny genetika metabolismus MeSH
- bioreaktory MeSH
- biosyntetické dráhy MeSH
- Brassica rapa MeSH
- Cupriavidus necator účinky léků genetika metabolismus MeSH
- fermentace MeSH
- hydroxybutyráty metabolismus MeSH
- mutageneze * MeSH
- oleje rostlin chemie metabolismus MeSH
- oxidační stres MeSH
- polyestery metabolismus MeSH
- polyhydroxyalkanoáty metabolismus MeSH
- průmyslový odpad MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Working from home during the Covid-19 pandemic was perceived differently by men and women working in STEM fields. The aim of this paper is to highlight the unexpected benefits generated by working from home during the pandemic. METHODS: Qualitative methodology was used to analyze data, collected via survey. The survey designed and conducted by WiMPBME targeted both males and females working in medical-related STEM fields (physics and engineering) and was answered by 921 individuals from 76 countries across all continents. This report analysed the responses to one open-ended question of the survey, namely: "What is the one positive that you have learnt/experienced as a result of working from home during this pandemic?". RESULTS: 594 responded to the question of interest. Access to home office was reported by 72.2% of survey participants. Males were more likely than females to report no positives of working from home (62.9%). Females were more likely to cite quality time, physical and mental health as positive factors than males, and to mention children in their responses. The most commonly coded thematic unit for males was remote working, with many males reporting the feasibility of working from home. Increased work productivity, better time management and work organisation were other common themes highlighted by responders irrespective of gender. CONCLUSION: The findings of the survey show the diversity of perceptions about remote working in STEM fields, while highlighting the importance of considering family dynamics, individual circumstances as well as gender when evaluating varied experiences of STEM professionals.
- MeSH
- COVID-19 * epidemiologie MeSH
- inženýrství MeSH
- lidé MeSH
- pandemie MeSH
- práce na dálku MeSH
- průzkumy a dotazníky MeSH
- sexuální faktory MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Heteronuclear and homonuclear direct (D) and indirect (J) spin-spin interactions are important sources of structural information about nucleic acids (NAs). The Hamiltonians for the D and J interactions have the same functional form; thus, the experimentally measured apparent spin-spin coupling constant corresponds to a sum of J and D. In biomolecular NMR studies, it is commonly presumed that the dipolar contributions to Js are effectively canceled due to random molecular tumbling. However, in strong magnetic fields, such as those employed for NMR analysis, the tumbling of NA fragments is anisotropic because the inherent magnetic susceptibility of NAs causes an interaction with the external magnetic field. This motional anisotropy is responsible for non-zero D contributions to Js. Here, we calculated the field-induced D contributions to 33 structurally relevant scalar coupling constants as a function of magnetic field strength, temperature and NA fragment size. We identified two classes of Js, namely (1)JCH and (3)JHH couplings, whose quantitative interpretation is notably biased by NA motional anisotropy. For these couplings, the magnetic field-induced dipolar contributions were found to exceed the typical experimental error in J-coupling determinations by a factor of two or more and to produce considerable over- or under-estimations of the J coupling-related torsion angles, especially at magnetic field strengths >12 T and for NA fragments longer than 12 bp. We show that if the non-zero D contributions to J are not properly accounted for, they might cause structural artifacts/bias in NA studies that use solution NMR spectroscopy.
Přecitlivělost na elektromagnetické pole (Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields) je relativně nový fenomén, který budí stále více pozornosti laické i odborné veřejnosti. Jsou zakládány společnosti, které mají za úkol pomoci takto postiženým, probíhá výzkum tohoto jevu a veřejné instituce vydávají svá stanoviska a doporučení k opatřením. Tento článek přináší přehled výsledků důležitých výzkumů a metaanalýz, které se zaměřily především na to, zda je elektromagnetické záření skutečně etiologickým činitelem, a dále přináší přehled hypotetických vysvětlení tohoto jevu.
Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields is a relatively new phenomenon, which is not fully understood. Extensive research has been carried out to exclude or confirm out that symptoms reported by sufferers are caused by electromagnetic field. This article describes outcomes of recent experiments and meta-analyses. The article may answer to the question if electromagnetic field does really cause reported symptoms, furthermore, it provides hypothetical explanation of this phenomenon.
Several groups of mammals use the Earth's magnetic field for orientation, but their magnetosensory organ remains unknown. The Ansell's mole-rat (Fukomys anselli, Bathyergidae, Rodentia) is a microphthalmic subterranean rodent with innate magnetic orientation behaviour. Previous studies on this species proposed that its magnetoreceptors are located in the eye. To test this hypothesis, we assessed magnetic orientation in mole-rats after the surgical removal of their eyes compared to untreated controls. Initially, we demonstrate that this enucleation does not lead to changes in routine behaviours, including locomotion, feeding and socializing. We then studied magnetic compass orientation by employing a well-established nest-building assay under four magnetic field alignments. In line with previous studies, control animals exhibited a significant preference to build nests in magnetic southeast. By contrast, enucleated mole-rats built nests in random magnetic orientations, suggesting an impairment of their magnetic sense. The results provide robust support for the hypothesis that mole-rats perceive magnetic fields with their minute eyes, probably relying on magnetite-based receptors in the cornea.
- MeSH
- lokomoce MeSH
- magnetické pole MeSH
- magnetismus MeSH
- mikroftalmičtí podzemní hlodavci * MeSH
- orientace * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
