Reentrant glass transition in a colloid-polymer mixture with depletion attractions

Performing light scattering experiments we show that introducing short-ranged attraction to a colloidal suspension of nearly hard spheres by addition of free polymer produces new glass transition phenomena. We observe a dramatic acceleration of the density fluctuations amounting to the melting of a colloidal glass. Increasing the strength of the attractions the system freezes into another nonergodic state sharing some qualitative features with gel states occurring at lower colloid packing fractions. This reentrant glass transition is in qualitative agreement with recent theoretical predictions.Comment: 14 pages, 3 figure

Lie experts' beliefs about non-verbal indicators of deception

ABSTRACT.. Beliefs about behavioral clues to deception were investigated in 212 people, consisting of prisoners, police detectives, patrol police officers, prison guards, customs officers, and college students. Previous studies, mainly conducted with college students as subjects, showed that people have some incorrect beliefs about behavioral clues to deception. It was hypothesized that prisoners would have the best notion about clues of deception, due to the fact that they receive the most adequate feedback about successful deception strategies. The results supported this hypothesis

The effect of cognitive load on faking interrogative suggestibility on the Gudjonsson Suggestibility Scale

In the light of recent studies into the impact of cognitive load on detecting deception, the impact of cognitive load on faking on the Gudjonsson Suggestibility Scale (GSS) was investigated. Eighty undergraduate students participated in the study, and were randomly assigned to one of four conditions resulting from a combination of the factors: instruction type (genuine or instructed faking, see Hansen, Smeets, & Jelicic, 2009) and concurrent task (yes or no). Findings show that instructed fakers, not performing a concurrent task, score significantly higher on yield 1 in comparison to genuine interviewees. This is in line with previous studies into faking on the GSS. However, instructed fakers, performing a concurrent task, achieved significantly lower yield 1 scores than instructed fakers not performing a concurrent task. Genuine (non fakers) showed a different response to increased cognitive load during the dual-task paradigm. This study suggests that increasing cognitive load may potentially indicate (and preclude) faking attempts on the yield dimension of the Gudjonsson Suggestibility Scale

Glasslike Arrest in Spinodal Decomposition as a Route to Colloidal Gelation

Colloid-polymer mixtures can undergo spinodal decomposition into colloid-rich and colloid-poor regions. Gelation results when interconnected colloid-rich regions solidify. We show that this occurs when these regions undergo a glass transition, leading to dynamic arrest of the spinodal decomposition. The characteristic length scale of the gel decreases with increasing quench depth, and the nonergodicity parameter exhibits a pronounced dependence on scattering vector. Mode coupling theory gives a good description of the dynamics, provided we use the full static structure as input.Comment: 14 pages, 4 figures; replaced with published versio

Capillary Waves in a Colloid-Polymer Interface

The structure and the statistical fluctuations of interfaces between coexisting phases in the Asakura-Oosawa (AO) model for a colloid--polymer mixture are analyzed by extensive Monte Carlo simulations. We make use of a recently developed grand canonical cluster move with an additional constraint stabilizing the existence of two interfaces in the (rectangular) box that is simulated. Choosing very large systems, of size LxLxD with L=60 and D=120, measured in units of the colloid radius, the spectrum of capillary wave-type interfacial excitations is analyzed in detail. The local position of the interface is defined in terms of a (local) Gibbs surface concept. For small wavevectors capillary wave theory is verified quantitatively, while for larger wavevectors pronounced deviations show up. For wavevectors that correspond to the typical distance between colloids in the colloid-rich phase, the interfacial fluctuations exhibit the same structure as observed in the bulk structure factor. When one analyzes the data in terms of the concept of a wavevector-dependent interfacial tension, a monotonous decrease of this quantity with increasing wavevector is found. Limitations of our analysis are critically discussed.Comment: 12 pages, 15 figure

Are there non-verbal signals of guilt?

Guilt is a complex emotion with a potentially important social function of stimulating cooperative behaviours towards and from others, but whether the feeling of guilt is associated with a recognisable pattern of nonverbal behaviour is unknown. We examined the production and perception of guilt in two different studies, with a total of 238 participants with various places of origin. Guilt was induced experimentally, eliciting patterns of movement that were associated with both the participants’ self-reported feelings of guilt and judges’ impressions of their guilt. Guilt was most closely associated with frowning and neck touching. While there were differences between self-reported guilt and perception of guilt the findings suggest that there are consistent patterns that could be considered a non-verbal signal of guilt in humans