AI Approaches to Cognitive Systems – The Example of Spatial Cognition

Cognitive abilities can be studied by observing and interpreting natural systems or by developing artificial systems that interact with their environments in intelligent ways. Cognitive systems research connects both approaches. Typically, human requirements are in the focus of interest and systems are developed to interact with humans in as natural a way as possible. To achieve this goal, a deep understanding of human cognition is required. The present paper focuses on spatial cognition, i. e. the ability to perceive and conceive spatial environments and solve spatial tasks intelligently. It discusses artificial intelligence approaches to spatial cognition for supporting human activities.     

Making Epothilones Fluoresce: Design,Synthesis, and Biological Characterization of a Fluorescent N12‐Aza‐Epothilone (Azathilone)

A green fluorescent 12‐aza‐epothilone (azathilone) derivative has been prepared through the attachment of the 4‐nitro‐2,1,3‐benzoxadiazole (NBD) fluorophore to the 12‐nitrogen atom of the azamacrolide core structure. While less potent than natural epothilones or different N12‐acylated azathilone derivatives, NBD‐azathilone ( 3 ) promotes tubulin assembly, inhibits cancer cell proliferation in vitro and arrests the cell cycle at the G2/M transition. Most significantly, the binding of 3 to cellular microtubules (MTs) could be directly visualized by confocal fluorescence microscopy. Based on competition binding experiments with laulimalide‐stabilized MTs in vitro, the N12‐Boc substituted azathilone 1 , Epo A, and NBD‐azathilone ( 3 ) all interact with the same tubulin‐binding site. Computational studies provided a structural model of the complexes between β‐tubulin and 1 or 3 , respectively, in which the NBD moiety of 3 or the BOC moiety of 1 directly and specifically contribute to MT binding. Collectively, these data demonstrate that the cellular effects of 3 and, by inference, also of other azathilones are the result of their interactions with the cellular MT network.     

Atomic force microscopy and Raman scattering studies of femtosecond laser-induced nanohillocks on CR-39

The phenomenon of nanohillock-like defect formation on the surfaces of CR-39 by ultra-short laser irradiation is investigated using an Atomic Force Microscope (AFM) and Raman Scattering. A polymer CR-39 target was exposed to Ti:sapphire 25-fs laser pulses with a central wavelength at 800 nm. Samples were irradiated for different laser fluences both in air and vacuum. Detailed surface topographical features of the bombarded samples were characterized by atomic force microscopy in contact mode in air at room temperature. AFM reveals that the growth of nanohillocks and their features are strongly dependent on the ambient condition, target position from focus, and irradiation fluence. The appearance of these nanohillocks in the range 1–20 nm in height and 10–90 nm in diameter are regarded as typical features for fast electronic processes (correlated with existence of hot electrons) and are explained on the basis of Coulomb explosion. These nanostructures due to localization of laser energy deposition in small areas provide a possible pathway from dense electronic excitation to atomic motion causing permanent structural modification which are well correlated to structural alterations, like crosslinking and chain scissions, inferred from Raman spectroscopy.     

Properties of Aqueous, Plastic Izer-Containing Ethyl Cellulose Dispersions and Prepared Films in Respect to the Production of oral Extended Release Formulations

Plasticized aqueous ethyl cellulose (EC) dispersions (Aquacoat^R ECD-30) are incompatible with concentrated electrolytes but stable with nonelectrolytes. The minimum film formation temperature (MFT) decreases with increasing plasticizer content, from 81°C to about 30°C with 20% dibutyl sebacate (DBS) in the resulting film. The plasticiser has to penetrate completely into the EC particles before film formation to obtain optimal plastification, the lowest film formation temperature and high permeability of the resulting film. This takes more than 5 hours with 20% DBS. Films prepared from plasticized dispersion with short standing times show craters of former plasticizer droplets. With increasing plasticizer content the sticking point of the films decreases. The plasticizer induce a high water absorption of the films: more than 30% with 23-26% DBS or diethyl phthalate (DEP). DBS is hardly released from the films within 5 hours, in contrast to DEP. Thus, the absorbed water is completely swelling water in case of DBS and partially also substitution water in case of DEP. The films squeeze out cetylalcohol (CA) and also sodium lauryl sulfate (NaLS) during storage, this may change the permeability of the films. EC contains a small amount of carboxylic groups which explains the pH dependent release of drugs from pellets coated with aqueous EC dispersions.     

Computer attitude in psychiatric inpatients

Negative computer attitude has been shown to be a possible co-variable in computerized examinations of psychiatric patients, affecting patient–computer interaction as well as reliability and validity of assessments.It remains still uncertain if the psychological construct of computer attitude can be dependably measured in acute psychiatric inpatients or whether it is impeded by the effects of mental illness. For that reason a German translation of the Groningen Computer Attitude Scale (GCAS) was evaluated in 160 acute psychiatric inpatients under naturalistic conditions.General test criteria (internal structure, item analysis, internal consistency, split half reliability) to a large extent corresponded to those formerly found in healthy subjects and psychiatric outpatients. The mean GCAS score was calculated as 56.2 ± 10.8 points and a significantly better computer attitude was found in male, better educated and younger patients. Some diverging correlation patterns were found in diagnostic subgroups, indicating a possible minor impact of mental disorder on computer attitude.Overall, the GCAS was found to be a suitable instrument for measuring computer attitude in acute psychiatric inpatients. It should be used in identifying patients with a negative attitude to computers in order to ensure reliability and validity of computerized assessment.     

Infrared characterization of the surface intermediates in the oxidation of toluene on vanadyl pyrophosphate catalysts

The adsorption and reaction of toluene on vanadyl pyrophosphate catalysts was studied by in situ infrared spectroscopy. Strongly adsorbed benzaldehyde and physically adsorbed cyclic anhydride species were observed at temperatures above 523 K. Water formed during reaction generates acid hydroxyl groups which cause a stronger adsorption of benzaldehyde and consecutive oxidation reactions. By co-adsorption of pyridine the acid sites are blocked and the deeper oxidation is suppressed. This revised version was published online in August 2006 with corrections to the Cover Date.