Hard sphere fluids in annular wedges: density distributions and depletion potentials

We analyze the density distribution and the adsorption of solvent hard spheres in an annular slit formed by two large solute spheres or a large solute and a wall at close distances by means of fundamental measure density functional theory, anisotropic integral equations and simulations. We find that the main features of the density distribution in the slit are described by an effective, two--dimensional system of disks in the vicinity of a central obstacle. For large solute--solvent size ratios, the resulting depletion force has a straightforward geometrical interpretation which gives a precise "colloidal" limit for the depletion interaction. For intermediate size ratios 5...10 and high solvent packing fractions larger than 0.4, the explicit density functional results show a deep attractive well for the depletion potential at solute contact, possibly indicating demixing in a binary mixture at low solute and high solvent packing fraction.Comment: 39 page

Atypical susceptibility to the rubber hand illusion linked to sensory-localised vicarious pain perception

The Rubber Hand Illusion (RHI) paradigm has been widely used to investigate the sense of body ownership. People who report experiencing the pain of others are hypothesised to have differences in computing body ownership and, hence, we predicted that they would perform atypically on the RHI. The Vicarious Pain Questionnaire (VPQ), was used to divide participants into three groups: 1) non-responders (people who report no pain when seeing someone else experiencing physical pain), 2) sensory-localised responders (report sensory qualities and a localised feeling of pain) and 3) affective-general responders (report a generalised and emotional feeling of pain). The sensory-localised group, showed susceptibility to the RHI (increased proprioceptive drift) irrespective of whether stimulation was synchronous or asynchronous, whereas the other groups only showed the RHI in the synchronous condition. This is not a general bias to always incorporate the dummy hand as we did not find increased susceptibility in other conditions (seeing touch without feeling touch, or feeling touch without seeing touch), but there was a trend for this group to incorporate the dummy hand when it was stroked with a laser light. Although individual differences in the RHI have been noted previously, this particular pattern is rare. It suggests a greater malleability (i.e. insensitivity to asynchrony) in the conditions in which other bodies influence own-body judgments

Different psychophysiological and clinical symptoms are linked to affective versus sensory vicarious pain experiences

For some people, seeing pain in others triggers a pain‐like experience in themselves: these experiences can either be described in sensory terms and localized to specific body parts (sensory‐localized, or S/L) or in affective terms and nonlocalized or whole‐body experiences (affective‐general, or A/G). In two studies, it is shown that these are linked to different clinical and psychophysiological profiles relative to controls. Study 1 shows that the A/G profile is linked to symptoms of Blood‐Injection‐Injury Phobia whereas the S/L profile shows some tendency toward eating disorders. Study 2 shows that the A/G profile is linked to poor interoceptive accuracy (for heartbeat detection) whereas the S/L profile is linked to higher heart‐rate variability (HRV) when observing pain, which is typically regarded as an index of good autonomic emotion regulation. Neither group showed significant differences in overall heart rate, systolic blood pressure (SBP), or skin conductance response (SCR) when observing pain, and no overall differences in state or trait anxiety. Overall, the research points to different underlying mechanisms linked to different manifestations of vicarious pain response. Affective‐General pain responders have strong subjective bodily experiences (likely of central origin given the absence of major differences in autonomic responsiveness) coupled with a worse ability to read objective interoceptive signals. Sensory‐localized pain responders have differences in their ability to construct a multi‐sensory body schema (as evidenced by prior research on the Rubber Hand Illusion) coupled with enhanced cardiovagal (parasympathetic) reactivity often indicative of better stress adaptation

Vicarious pain is an outcome of atypical body ownership: evidence from the rubber hand illusion and enfacement illusion

Some people report localised pain on their body when seeing other people in pain (sensory-localised vicarious pain responders). In this study we assess whether this is related to atypical computations of body ownership which, in paradigms such as the Rubber Hand Illusion (RHI), can be conceptualised as a Bayesian inference as to whether multiple sources of sensory information (visual, somatosensory) belong together on a single body (one’s own) or are distributed across several bodies (vision=other, somatosensory=self). According to this model, computations of body ownership depend on the degree (and precision) of sensory evidence, rather than synchrony per se. Sensory-localised vicarious pain responders exhibit the RHI following synchronous stroking and – unusually – also after asynchronous stroking. Importantly, this occurs only in asynchronous conditions in which the stroking is predictable (alternating) rather than unpredictable (random). There was no evidence that their bottom-up proprioceptive signals are less precise, suggesting individual differences in the top-down weighting of sensory evidence. Finally, the Enfacement illusion (EI) was also employed as a conceptually-related bodily illusion paradigm that involves a completely different response judgment (based on vision rather than proprioception). Sensory-localised responders show a comparable pattern on this task after synchronous and asynchronous stroking. This is consistent with the idea that they have top-down (prior) differences in the way body ownership is inferred that transcends the exact judgment being made (visual or proprioceptive)

Two-Dimensional Spectroscopy of Extended Molecular Systems: Applications to Energy Transport and Relaxation in an α-Helix

A simulation study of the coupled dynamics of amide I and amide II vibrations in an α-helix dissolved in water shows that two-dimensional (2D) infrared spectroscopy may be used to disentangle the energy transport along the helix through each of these modes from the energy relaxation between them. Time scales for both types of processes are obtained. Using polarization-dependent 2D spectroscopy is an important ingredient in the method we propose. The method may also be applied to other two-band systems, both in the infrared (collective vibrations) and the visible (excitons) parts of the spectrum.

Trait phenomenological control predicts experience of mirror synaesthesia and the rubber hand illusion

In hypnotic responding, expectancies arising from imaginative suggestion drive striking experiential changes (e.g., hallucinations) — which are experienced as involuntary — according to a normally distributed and stable trait ability (hypnotisability). Such experiences can be triggered by implicit suggestion and occur outside the hypnotic context. In large sample studies (of 156, 404 and 353 participants), we report substantial relationships between hypnotisability and experimental measures of experiential change in mirror-sensory synaesthesia and the rubber hand illusion comparable to relationships between hypnotisability and individual hypnosis scale items. The control of phenomenology to meet expectancies arising from perceived task requirements can account for experiential change in psychological experiments

Voluntary disclosure of corporate strategy: determinants and outcomes. An empirical study into the risks and payoffs of communicating corporate strategy.

Business leaders increasingly face pressure from stakeholders to be transparent. There appears however little consensus on the risks and payoffs of disclosing vital information such as corporate strategy. To fill this gap, this study analyzes firm-specific determinants and organisational outcomes of voluntary disclosure of corporate strategy. Stakeholder theory and agency theory help to understand whether companies serve their interest to engage with stakeholders and overcome information asymmetries. I connect these theories and propose a comprehensive approach to measure voluntary disclosure of corporate strategy. Hypotheses from the theoretical framework are empirically tested through panel regression of data on identified determinants and outcomes and of disclosed strategy through annual reports, corporate social responsibility reports, corporate websites and corporate press releases by the 70 largest publicly listed companies in the Netherlands from 2003 through 2008. I found that industry, profitability, dual-listing status, national ranking status and listing age have significant effects on voluntary disclosure of corporate strategy. No significant effects are found for size, leverage and ownership concentration. On outcomes, I found that liquidity of stock and corporate reputation are significantly influenced by voluntary disclosure of corporate strategy. No significant effect is found for volatility of stock. My contributions to theory, methodology and empirics offers a stepping-stone for further research into understanding how companies can use transparency to manage stakeholder relations

The infrared driven cis-trans isomerization reaction of nitrous acid (HONO) and energy transport in peptide helices

This thesis contains the results of two distinct scientific inquiries. The first part investigates a model system for ground state chemical reactions whereas the second part examines the energy transport in peptide helices. The cis-trans isomerization of nitrous acid (HONO) in solid matrices is a model system of a chemical reaction in the electronic ground state. The isomerization reaction is reversible and can be triggered by the photo-excitation of the OH stretch. Exciting OHcis in an IR pump - IR probe experiment, we observed vibrationally hot trans molecules on an ultrafast time scale (20-50 ps) with the isomerization following a two step process. The first step corresponds to the direct coupling of the vibrational excited state with the reaction channel state(s), whereas the second step represents the energy that is re-fed in the reaction channel from intermediate states (states that get populated by the OHcis). The quantum yield of the cis!trans isomerization reaction after exciting OHcis increases by 30% when cooling the matrix from 30 K to 15 K, being (at the low temperature) 50-70%. We also estimated that the quantum yield of the backward reaction decreases by approximatively 40% in the same temperature range. This behavior is explained in the framework of Marcus theory of electron and proton transfer in the barrierless regime. In this regime, the theory predicts a 40% increase in quantum yield of the forward reaction, in agreement with the 30% from experiment. Hence, quantum yield could go up to 100% at sufficiently low temperatures. A wealth of information about the dynamics of the isomerization reaction and the cooling process following excitation was obtained by performing two color experiments, in which OH stretch, N=O stretch and HON bend were excited and probed in different combinations. The rotational dynamics of the cis and trans isomers were investigated in the Kr matrix at 30 K. We observed that the central atoms of the molecule rotate in a hula hoop motion upon the H isomerization. With these series of experiments, we were the first to study the ultrafast dynamics of a ground state reaction in the low excitation regime. To investigate the mechanism of heat transport in peptide helices, we designed an eight amino acid peptide helix to which we attached an azobenzene chromophore. After exciting the azobenzene with a UV pulse, we followed the heat propagation through the helix using the shifts in the amide I band in the IR. With the help of isotope labeling, we were able to spectroscopically isolate specific amino acids in the sequence at different positions along the helix. We found that the heat does not propagate through the hydrogen bonds, as it was theoretically suggested, but rather through the backbone of the helix. Furthermore, fitting our data to a rate equation system, we estimated a heat diffusion coefficient D=2 Å2/ps. Exciting the molecule with IR light, we calculated a heat diffusivity coefficient four times higher than the one when UV excitation was used. Below 270 K, the heat transport is inefficient and mostly ballistic whereas above this temperature it is more efficient and diffusive in character. These studies are the first steps towards the investigation of vibrational energy transport in large bio-polymers and proteins