Macroscopic Properties of Open-Cell Foams Based on Micromechanical Modelling

This paper presents a micromechanical analysis for the assessment of macroscopic behaviour of threedimensional open-cell solid foams. The analysis is based on material properties of a solid phase and topological arrangement of cell structure. A foam structure consists of idealized tetrahedral unit cells, which are built of four identical half-struts forming a diamond-like structure and identified as Plateau borders. Such a unit cell represents the essential microstructural features of foam. An analytical formulation of force-displacement relations for struts can be found by considering the affinity of node displacements in tensile, bending, and shear deformation. The elements of the stiffness matrix for a single cell are expressed as functions of the compliance coefficients for stretching and bending of struts. The effective elastic constants for metallic foam considered as isotropic material are determined as functions of foam relative density and compared with available results. In this paper we define an energy-based limit condition of linear elasticity for open-cell foams and calculate the critical energy density pertinent to a particular orthogonal energy state accounting for elementary interactions in a microstructure. The study based on the assumption of linear elasticity leads to simple analytical formulas. Nevertheless, it should be stressed that the proposed theoretical basis of micromechanical modelling could be also applied for the analysis of nonlinear elastic behaviour, plasticity, and failure of foams. Such problems require, however, a more complex numerical approach

Effect of multi-component fertilizers on seeds yield, yield components and physiological parameters of winter oilseed rape (Brassica napus L.)

ArticleSubject of the discussed studies was an analysis of the impact of mineral multicomponent fertilizers, from Polish and foreign producers, on the yield and yield components of winter oilseed rape (Brassica napus var. oleifera). Two field experiments were carried out in 2015–2017 in Lipnik. The experimental crop was winter oilseed rape, hybrid cultivar DK EXPLICIT. Two factors were studied in the experiment A: 4 multi-component mineral fertilizers - two Belarusian (1 i 2), one Russian and one Polish (Polifoska 6) and 4 doses of fertilization (250, 500 and 750 kg ha-1 ). In the experiment (B) were compared two factors: 3 multi-component mineral fertilizers - Belarusian, Russian and Polish production - Polifoska 8 and 4 doses of fertilization (200, 400 and 600 kg ha-1 ). The fertilizers applied in the experiments, manufactured in Belarus, Russia and Poland, did not show variations in the amount of yield of winter rape. The number of winter rapeseed plants on the area unit (in autumn and spring) was independent of the type of fertilizers. In the experiment B, higher number of rapeseed siliques was obtained after application of Polifoska 8, than other fertilizers. Rapeseed grown on soil with the fertilizers manufactured in Belarus showed a lower value of greenness index (SPAD) and leaf area index (LAI). As a result of the application of multi-component fertilizers, manufactured in Belarus, Russia and Poland, the recorded differences in the winter rapeseed yield, yield components and physiological parameters did not exceed 10%

Binaries with total eclipses in the LMC: potential targets for spectroscopy

35 Eclipsing binaries presenting unambiguous total eclipses were selected from a subsample of the list of Wyrzykowski et al. (2003). The photometric elements are given for the I curve in DiA photometry, as well as approximate Teff and masses of the components. The interest of these systems is stressed in view of future spectroscopic observations.Comment: 4 pages, 1 figure; poster presented at the conference "Close binaries in the 21st Century: new opportunities and challenges", Syros, 27-30 June 200

Genetic imaging of the association of oxytocin receptor gene (OXTR) polymorphisms with positive maternal parenting

Background: Well-validated models of maternal behavior in small-brain mammals posit a central role of oxytocin in parenting, by reducing stress and enhancing the reward value of social interactions with offspring. In contrast, human studies are only beginning to gain insights into how oxytocin modulates maternal behavior and affiliation. Methods: To explore associations between oxytocin receptor genes and maternal parenting behavior in humans, we conducted a genetic imaging study of women selected to exhibit a wide range of observed parenting when their children were 4-6 years old. Results: In response to child stimuli during functional magnetic resonance imaging (fMRI), hemodynamic responses in brain regions that mediate affect, reward, and social behavior were significantly correlated with observed positive parenting. Furthermore, single nucleotide polymorphisms (SNPs) (rs53576 and rs1042778) in the gene encoding the oxytocin receptor were significantly associated with both positive parenting and hemodynamic responses to child stimuli in orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and hippocampus. Conclusions: These findings contribute to the emerging literature on the role of oxytocin in human social behavior and support the feasibility of tracing biological pathways from genes to neural regions to positive maternal parenting behaviors in humans using genetic imaging methods. © 2014 Michalska, Decety, Liu, Chen, Martz, Jacob, Hipwell, Lee, Chronis-Tuscano, Waldman and Lahey

Digital Politics: Mobilization, Engagement, and Participation

The article provides insights into the driving forces that underpin new forms of political participation. Digital technologies offer opportunities for engaging in a wide range of civicallyoriented activities, each of which can contribute to deeper democratic engagement. Conventional acts of political participation are argued to be driven primarily by intrinsic motivations relating to self-efficacy and empowerment with participants feeling they can have influence over decision makers. Little research explores whether similar motivations drive participation in less conventional acts, as well as whether mobilisation attempts via social media by peers or political organisations mediate those motivations. Drawing on data from a survey among a representative sample of the UK electorate, we find the offline and online spheres of agency remain fairly distinct. Intrinsic and extrinsic motivations both matter but extrinsic motivations have the strongest explanatory power independent of the sphere of activity. The mediating effect of mobilisation tactics has a minimal effect on extrinsic motivations, online or offline, but online intrinsic motivations lose their explanatory power. As intrinsic factors offer little explanatory power some forms of online political participation may lack meaning to the individual. Rather, these non-conventional acts result from reward seeking and are more likely to be encouraged by non-governmental campaigning organizations suggesting social media users are most likely to perform simple acts in support of non-contentious causes

Atypical empathic responses in adolescents with aggressive conduct disorder: A functional MRI investigation

Abstract Because youth with aggressive conduct disorder (CD) often inflict pain on others, it is important to determine if they exhibit atypical empathic responses to viewing others in pain. In this initial functional magnetic resonance imaging (fMRI) study, 8 adolescents with aggressive CD and 8 matched controls were scanned while watching animated visual stimuli depicting other people experiencing pain or not experiencing pain. Furthermore, these situations involved either an individual whose pain was caused by accident or an individual whose pain was inflicted on purpose by another person. After scanning, participants rated how painful the situations were. In both groups the perception of others in pain was associated with activation of the pain matrix, including the ACC, insula, somatosensory cortex, supplementary motor area and periaqueductal gray. The pain matrix was activated to a significantly greater extent in participants with CD, who also showed strong amygdala, ventral striatum, and temporal pole activation. When watching situations in which pain was intentionally inflicted, control youth also exhibited signal increase in the medial prefrontal frontal cortex, lateral obitofrontal cortex, and temporoparietal junction, whereas youth with CD only exhibited activation in the insula. Furthermore, connectivity analyses demonstrated that youth with CD exhibited less amygdala/prefrontal coupling when watching pain inflicted by another than did control youth. These preliminary findings suggest that youth with aggressive CD exhibit an atypical pattern of neural response to viewing others in pain that should be explored in further studies

UVSat: a concept of an ultraviolet/optical photometric satellite

Time-series photometry from space in the ultraviolet can be presently done with only a few platforms, none of which is able to provide wide-field long-term high-cadence photometry. We present a concept of UVSat, a twin space telescope which will be capable to perform this kind of photometry, filling an observational niche. The satellite will host two telescopes, one for observations in the ultraviolet, the other for observations in the optical band. We also briefly show what science can be done with UVSat.Comment: 6 pages, 2 figures, accepted for publication in the Proceedings of the PAS (Proc. of the 2nd BRITE Science conference, Innsbruck