Gasgevulde microgestructureerde stralingsdetectoren

Applied Science

A model for the effect of disturbances in the optical media on the OCT image quality.

PURPOSE. The loss of quality of optical coherence tomography (OCT) images resulting from disturbances in the optical media has been modeled. METHODS. OCT measurements were performed in two healthy volunteers using time domain (TD)-OCT (StratusOCT; Carl Zeiss Meditec, Dublin, CA). Optical disturbances were approached in three ways simulated with filters. The studied effects were: light attenuation (absorptive and reflective filters), refractive aberrations (defocusing lenses), and light scattering/straylight (scattering filters). The same examiner scanned the subjects with the filters placed in front of the eye. The signal strength (SS) values of the scans were then collected. The strength of the filters were expressed in optical density (OD), determined for the 830 nm central wavelength of the OCT, (OD lambda=830). RESULTS. A linear relationship has been found between the OD lambda=830 of the absorptive and reflective filters and the SS of the corresponding OCT images. Assuming that reduction of light from the OCT scanning spot on the retina is the critical factor, this light loss was determined for the scattering filters and defocusing lenses. A comparable linear relationship was found between the SS value and the OD lambda=830 of these filters. CONCLUSIONS. The model indicates that the loss of OCT image quality in patients with disturbances in the optical media is explained by attenuation of the light in the OCT scanning spot on the retina. A linear relationship between the SS and the single pass logarithmic attenuation of the OCT signal is shown, according to SS = constant-(9.9 [-9.4 to-10.6] . OD lambda=830). (Invest Ophthalmol Vis Sci. 2009;50:787-792) DOI:10.1167/iovs.08-236

Sales presentation anxiety, cortisol levels, self-reports, and gene-gene interactions

We study sales presentation anxiety (SPA) using multilevel analysis of a quasi-natural field experiment: the final exam of an executive training course where sales professionals (n = 128) compete in teams to present an account plan to a critical audience who then ask questions and evaluate their performance. The best team is announced the winner of the competition. Compared to pre-presentation levels, overall cortisol (C) levels first increased after the question period and subsequently decreased 20 and 50 minutes after, indicating a relatively fast recovery rate. Negative significant correlations were found between self-reported experience of stress and C levels in periods 3 and 4 which might indicate affect labeling, a coping technique that focuses on the underlying physiological response. Using two candidate genes, DRD2 and DRD4, we investigated associations between C levels in the four periods. Carriers of DRD2 Taq A1+ and DRD4 7R+ alleles had lower C levels compared to non-carriers, both right after the question period and 20 minutes later which might indicate flexibility in using coping strategies involving distraction from the task. The gained insights reveal that SPA entails multilevel processes that affect one another reciprocally

Theory of mind and empathic explanations of Machiavellianism: a neuroscience perspective

We study theory of mind (ToM) and empathic underpinnings of Machiavellianism by use of functional magnetic resonance imaging, where account managers are used as participants in 3 studies. Study 1 finds evidence for activation of the medial prefrontal cortex, left and right temporo-parietal junction, and left and right precuneus regions; all five regions are negatively correlated with Machiavellianism, suggesting that Machiavellians are less facile than non-Machiavellians with ToM skills. Study 2 presents evidence for activation of the left and right pars opercularis, left and right insula, and left precuneus regions; the former four regions of the motor neuron system were positively associated, and the latter negatively associated, with Machiavellianism, implying that Machiavellians resonate more readily with the emotions of others than non-Machiavellians. This is the first study to our knowledge to show a negative correlation between perspective taking and emotional sharing in empathic processes in general and Machiavellianism in particular. Study 3 tests implications of managerial control on both performance and organizational citizenship behaviors, as moderated by Machiavellianism in the field. Our study grounds the functioning of Machiavellianism in organizations in basic neuroscience processes, resolves some long-standing ambiguities with self-report investigations, and points to conditions under which Machiavellianism both inhibits and promotes performance and citizenship behavior

Gas gain stability of MSGCs operating at high rate

Micro Strip Gas Counters (MSGCs) with coated and uncoated borosilicate glass substrates have been investigated on their high rate capability and long-term gas gain stability. It is shown that the gain remains almost constant at count rates up to 105 mm-2 s-1 when a semiconductive layer of S8900 glass or polydiamond is applied under or over the strips. The application of such a coating also favours the gain stability at long-term operation. However, the maximum attainable gas gain for coated substrates is 4-10 times smaller than for bare borosilicate glass supports. For the latter substrate type, we observe less ageing when the strips are made of nickel instead of aluminium or copper.SCOPUS: ar.jinfo:eu-repo/semantics/publishe