Two opinions dynamics generated by inflexibles and non-contrarian and contrarian floaters

We assume a community whose members adopt one of two opinions $A$ or $B$. Each member appears as an inflexible, or as a non-contrarian or contrarian floater. An inflexible sticks to its opinion, whereas a floater may change into a floater of the alternative opinion. The occurrence of this change is governed by the local majority rule: members meet in groups of a fixed size, and a floater then changes its opinion provided it is a minority in the group. Subsequently, a non-contrarian floater keeps the opinion as adopted under the local majority rule, whereas a contrarian floater adopts the alternative opinion. Whereas the effects of on the one hand inflexibles and on the other hand non-contrarians and contrarians have previously been studied seperately, the current approach allows us to gain insight in the effect of their combined presence in a community. Given fixed proportions of inflexibles $(\alpha_{A}, \alpha_{B})$ for the two opinions, and fixed fractions of contrarians $(\gamma_{A}, \gamma_{B})$ among the $A$ and $B$ floaters, we derive the update equation $p_{t+1}$ for the overall support for opinion $A$ at time $t+1$, given $p_{t}$. The update equation is derived respectively for local group sizes 1, 2 and 3. The associated dynamics generated by repeated local updates is then determined to identify its asymptotic steady configuration. The full opinion flow diagram is thus obtained, showing conditions in terms of the parameters for each opinion to eventually win the competing dynamics. Various dynamical scenarios are thus exhibited, and it is derived that relatively small densities of inflexibles allow for more variation in the qualitative outcome of the dynamics than higher densities of inflexibles.Comment: 45 pages and 13 figure

Transfer of Sulfamethazine from Contaminated Beeswax to Honey

A liquid chromatographic tandem mass spectrometric method for the determination of sulfa drugs in beeswax was developed. When performing residue control on beeswax intended for the fabrication of wax foundations, residues of sulfonamides were found. A migration test was set up to study whether sulfonamide-containing beeswax could lead to the contamination of honey. The higher the concentration of sulfamethazine doped in the wax, the higher was the concentration of sulfamethazine found in the honey. The maximum transfer was 15.6, 56.9, and 29.5% of the initial amount spiked in the wax foundation. In a second experiment, the percentage of sulfamethazine migrating from medicated winter feed to beeswax in relation to the concentration in the syrup and the contact time was studied. The maximum transfer of sulfamethazine from medicated sucrose syrup to beeswax was 3.1%

Influence of spray drying suspension on the morphology of Fe-based oxygen carriers for chemical looping

Chemical looping reforming (CLR) and chemical looping combustion (CLC) are promising technologies with inherent CO2 capture for transforming fuels into syngas and energy respectively. Circulating oxygen carriers (OC) are used to transfer oxygen from mostly air to the fuel inside the process. Over the past years a variety of materials have been proposed for the role of oxygen carriers, ranging from bulk mineral powders to oxygen carrier particles engineered for shape, size and composition. Iron based materials are very promising and cost effective candidates with minor impact on the environment as compared to the toxic Ni-based OCs. Granulation by the industrial spray-drying technique is suitable for producing oxygen carrier particles with high sphericity and dimensions fit for the fluidized-bed reactors of the CL-process. The lifetime of the oxygen carriers in these reactors however strongly depends on their mechanical properties (as measured by the crushing strength and the attrition resistance) which is related with their morphology and porosity. As this morphology depends on the spray drying suspension, the relation between the additives used in the iron-based suspension and the morphology of the spray-dried particles is investigated in this work [1]. The influence of the concentration of the binder, dispersing agent and solids in the spray-drying suspensions and the intensity of the milling procedure on the morphology and microstructure of the resulting particles is studied by Hg-porosimetry, tapped density, optical microscopy and SEM. A controlled sintering treatment is used during post-processing of these spray-dried particles in order to further improve their mechanical properties before investigating their performance as oxygen carriers in the chemical looping process

An Explanation for the Role of the Amygdala in Aesthetic Judgments

Contains fulltext : 168787.pdf (publisher's version ) (Open Access)It has been proposed that the top-down guidance of feature-based attention is the basis for the involvement of the amygdala in various tasks requiring emotional decision-making (Jacobs, Renken, Aleman & Cornelissen, 2012). Aesthetic judgements are correlated with particular visual features and can be considered emotional in nature (Jacobs et al., 2016). Moreover, we have previously shown that various aesthetic judgements result in observers preferentially attending to different visual features (Jacobs et al., 2010). Here, we argue that - together - this explains why the amygdalae become active during aesthetic judgements of visual materials. We discuss potential implications and predictions of this theory that can be tested experimentally.7 p

Identification of regulatory elements mediating responses of SOD and cystatin transcripts to salt stress and nitric oxide in soybean nodules

Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Nitric oxide (NO) has previously been shown to play a vital role in plants that are undergoing oxidative stress arising from abiotic stress. To better understand the role of NO on the antioxidative pathway, the effect of NO on Superoxide Dismutase (SOD) activity was studied during salt stress on soybean nodules. The enzymatic activity of specific MnSOD and FeSOD isoforms increased upon 1 week of exposure of nodules to NO or salt stress, the activity of CuZnSOD isoforms however increased in response to salt stress only. Furthermore, 4 putative FeSOD and MnSOD transcripts were identified and shown to increase in response to NO and salt stress. The promoter sequences of these NO-responsive putative SOD genes were analysed alongside a cystatin (AtCYS-1) which is also NO-inducible. Putative NO-responsive cis-acting elements as well as abiotic stress-responsive cis-acting elements were studied amongst these promoter sequences. The MYCL element and the AtMYB4 binding site were found to occur in all four NO-inducible SOD promoter sequences as well as in the AtCYS-1 promoter sequence. This suggests that NO acts via MYCL and/or AtMYB4 to up-regulate specific FeSODs and MnSODs, causing an increase in the activity of these SOD isoforms, thus reducing oxidative stress and cell death in soybean nodules. Furthermore, NO may also be up-regulating cystatins to inhibit cysteine proteases, thus preventing the onset of programmed cell death (PCD) and subsequently reducing salt stress-induced cell death.AFRIKAANSE OPSOMMING: Geen opsommin

Different judgments about visual textures invoke different eye movement patterns

Top-down influences on the guidance of the eyes are generally modeled as modulating influences on bottom-up salience maps. Interested in task-driven influences on how, rather than where, the eyes are guided, we expected differences in eye movement parameters accompanying beauty and roughness judgments about visual textures. Participants judged textures for beauty and roughness, while their gaze-behavior was recorded. Eye movement parameters differed between the judgments, showing task effects on how people look at images. Similarity in the spatial distribution of attention suggests that differences in the guidance of attention are non-spatial, possibly feature-based. During the beauty judgment, participants fixated on patches that were richer in color information, further supporting the idea that differences in the guidance of attention are feature-based. A finding of shorter fixation durations during beauty judgments may indicate that extraction of the relevant features is easier during this judgment. This finding is consistent with a more ambient scanning mode during this judgment. The differences in eye movement parameters during different judgments about highly repetitive stimuli highlight the need for models of eye guidance to go beyond salience maps, to include the temporal dynamics of eye guidance

In vivo imaging of the nucleus of the solitary tract with Magnetization Transfer at 7 Tesla

The nucleus of the solitary tract (NTS) is a nuclei complex with, among others, a high concentration of noradrenergic neurons (including the noradrenergic subnuclei named A1 and A2) in the medulla. The NTS regulates several cognitive, neuroendocrine and autonomic functions. No method currently exists to anatomically visualize the NTS in vivo. Several noradrenergic and dopaminergic nuclei have been successfully imaged using Magnetization Transfer (MT) contrast manipulation. We therefore hypothesized that an efficient, high-resolution MT-weighted sequence at 7 T might successfully image the NTS. In this study, we found a hyperintensity, similar to hyperintensities found in other noradrenergic and dopaminergic nuclei, consistent with the expected NTS location, and specific to the MT-weighted images. The localization of the hyperintensity was found to be consistent between individuals and slices and in good correspondence to a histological atlas and a meta-analytic map of fMRI-based NTS activation. We conclude that the method may, for the first time, achieve NTS imaging in vivo and within a clinically-feasible acquisition time. To facilitate NTS research at lower field strengths, an NTS template was created and made publicly available

The role of inflexible minorities in the breaking of democratic opinion dynamics

We study the effect of inflexible agents on two state opinion dynamics. The model operates via repeated local updates of random grouping of agents. While floater agents do eventually flip their opinion to follow the local majority, inflexible agents keep their opinion always unchanged. It is a quenched individual opinion. In the bare model (no inflexibles), a separator at 50% drives the dynamics towards either one of two pure attractors, each associated with a full polarization along one of the opinions. The initial majority wins. The existence of inflexibles for only one of the two opinions is found to shift the separator at a lower value than 50% in favor of that side. Moreover it creates an incompressible minority around the inflexibles, one of the pure attractors becoming a mixed phase attractor. In addition above a threshold of 17% inflexibles make their side sure of winning whatever the initial conditions are. The inflexible minority wins. An equal presence of inflexibles on both sides restores the balanced dynamics with again a separator at 50% and now two mixed phase attractors on each side. Nevertheless, beyond 25% the dynamics is reversed with a unique attractor at a fifty-fifty stable equilibrium. But a very small advantage in inflexibles results in a decisive lowering of the separator at the advantage of the corresponding opinion. A few percent advantage does guarantee to become majority with one single attractor. The model is solved exhaustedly for groups of size 3.Comment: 18 pages, 12 figure

Alzheimer's disease pathology:pathways between central norepinephrine activity, memory, and neuropsychiatric symptoms

The locus coeruleus (LC) supplies norepinephrine to the brain, is one of the first sites of tau deposition in Alzheimer's disease (AD) and modulates a variety of behaviors and cognitive functions. Transgenic mouse models showed that norepinephrine dysregulation after LC lesions exacerbates inflammatory responses, blood-brain barrier leakage (BBB), and cognitive deficits. Here, we investigated relationships between central norepinephrine metabolism, tau and beta-amyloid (Aβ), inflammation, BBB-dysfunction, neuropsychiatric problems, and memory in-vivo in a memory clinic population (total n = 111, 60 subjective cognitive decline, 36 mild cognitively impaired, and 19 AD dementia). Cerebrospinal fluid (CSF) and blood samples were collected and analyzed for 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG), CSF/plasma albumin ratio (Q-alb), Aβ, phosphorylated tau, and interleukins. The verbal word learning task and the neuropsychiatric inventory assessed memory functioning and neuropsychiatric symptoms. Structural equation models tested the relationships between all fluid markers, cognition and behavior, corrected for age, education, sex, and clinical dementia rating score. Our results showed that neuropsychiatric symptoms show strong links to both MHPG and p-tau, whereas memory deficits are linked to MHPG via a combination of p-tau and inflammation-driven amyloidosis (30-35% indirect effect contribution). These results suggest that the LC-norepinephrine may be pivotal to understand links between AD pathology and behavioral and cognitive deficits in AD