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Biomedical subjects

Michal Lahav

Publications and source records attributed to Michal Lahav.

6 recordsLinked to original sources

Unobtrusive vehicle motion prediction cues reduced simulator sickness during passive travel in a driving simulator.

This study investigated cues that permit prediction of turns during passive movement through a virtual environment. Effects on simulator sickness (SS), presence and enjoyment were examined. Subjects were exposed to complex visual motion through a cartoon-like simulated environment in a driving simulator. Forward velocity remained constant and the motion path was the same across all experimental conditions. Using a within-subject design, we examined visual paths that provided different levels of cue salience - detailed, simplified and no cues - for the upcoming simulated vehicle motion. Following each trial, participants completed questionnaires on SS, presence and enjoyment. After all of the trials were completed, a debriefing determined participants' perceptions of vehicle motion attributes and their awareness of the prediction cues. The results showed that SS in the no-cue condition was significantly greater than that in the conditions that provided vehicle motion cues. Presence and enjoyment responses were not different across the conditions. No participants reported differences between prediction cue conditions or recognized that the vehicle motion followed the same path across trials. However, participants tended to report that the motion was smoother for the detailed-cue than the no-cue condition. Participants ranked turn predictability as higher in conditions with prediction cues. The results support the hypothesis that unobtrusive and unreported motion cues may alleviate SS in a virtual environment.

Adolescent↗

Approaching zero: using fractured crystals in metrology for replica molding.

This report presents a simple and convenient method to generate nanoscale fractures (cracks) in smooth, single-crystalline Si substrates. The cracks propagated as approximately straight lines along the {100} crystal planes with controllable length defined by a stabilizing backlayer. Close to its tip, the crack presented a vertical offset of the two planes as step of smoothly decreasing height, ranging from the microscale to the atomic scale. The edges of a crack were in close contact at the tip of the crack but were separated at the edge where the crack was initiated. These steps served as ideal test features for probing the limits of the replication of soft lithography. Analysis of topography of original and replicated features (in "hard" poly(dimethylsiloxane and polyurethane) by atomic force microscopy demonstrated that steps down to 0.4 nm could be reproduced; these features approach the dimensions of atoms.

Crystallization↗

Biological sensing using transmission surface plasmon resonance spectroscopy.

Ultrathin gold island films evaporated on transparent substrates offer promising transducers for chemical and biological sensing in the transmission surface plasmon resonance (T-SPR) mode. In the present work, the applicability of T-SPR-based systems to biosensing is demonstrated, using a well-established biological model system. Au island films were evaporated on polystyrene slides and modified with a biotinylated monolayer via a multistep surface reaction, the latter assisted by the good adhesion of metal islands to polystyrene. The biotin-derivatized Au island film was then used as a biological recognition surface for selective sensing of avidin binding, distinguishing between specific and nonspecific binding to the substrate. Transduction of the binding event into an optical signal was achieved by T-SPR spectroscopy, using plasmon intensity measurements, rather than wavelength change, for maximal sensitivity and convenience. T-SPR spectroscopy of Au island films is shown to be an effective tool for monitoring the binding of biological molecules to receptor layers on the Au surface and a promising approach to label-free optical biosensing.

Biosensing Techniques↗

Hydration of Alkynes by a PtCl(4)-CO Catalyst.

Treatment of PtCl(4) with CO at 40-110 degrees C forms a powerful alkyne hydration catalyst that operates both under homogeneous conditions in wet THF and under phase-transfer conditions in (CHCl(2))(2)/H(2)O in the presence of tricaprylmethylammonium chloride (Aliquat 336). Complex HPtCl(CO)(2) is regarded as the active hydration catalyst. It is assumed to be formed by initial transformation of PtCl(4) to H(2)[Pt(3)(CO)(6)](n) (n = 5, 6) followed by reaction with HCl (generated by decomposition of the starting platinum salt).

Journal Article↗