Action adaptation during natural unfolding social scenes influences action recognition and inferences made about actor beliefs.

When observing another individual's actions, we can both recognize their actions and infer their beliefs concerning the physical and social environment. The extent to which visual adaptation influences action recognition and conceptually later stages of processing involved in deriving the belief state of the actor remains unknown. To explore this we used virtual reality (life-size photorealistic actors presented in stereoscopic three dimensions) to see how visual adaptation influences the perception of individuals in naturally unfolding social scenes at increasingly higher levels of action understanding. We presented scenes in which one actor picked up boxes (of varying number and weight), after which a second actor picked up a single box. Adaptation to the first actor's behavior systematically changed perception of the second actor. Aftereffects increased with the duration of the first actor's behavior, declined exponentially over time, and were independent of view direction. Inferences about the second actor's expectation of box weight were also distorted by adaptation to the first actor. Distortions in action recognition and actor expectations did not, however, extend across different actions, indicating that adaptation is not acting at an action-independent abstract level but rather at an action-dependent level. We conclude that although adaptation influences more complex inferences about belief states of individuals, this is likely to be a result of adaptation at an earlier action recognition stage rather than adaptation operating at a higher, more abstract level in mentalizing or simulation systems.

Use of Nitrogen-15-Enriched Escherichia coli as a Bacterial Tracer in Karst Aquifers.

Karst aquifers are susceptible to contamination by microorganisms, but relatively few studies have used bacteria as tracers. We demonstrate the utility of Escherichia coli enriched in the stable isotope nitrogen-15 (15 N) as a novel bacterial tracer. Nonpathogenic E. coli from two springs in central Kentucky were grown on 15 N-enriched media. Survival of E. coli and persistence of the isotopic signal were assessed in two sets of laboratory experiments conducted with sterilized spring water in dark microcosms at 14 °C. First, isotopically labeled bacteria survived for 130 d at concentrations within one log unit of the average initial value, and there was no significant difference in δ15 N values from Day 1 to Day 130. Second, water samples with E. coli were inoculated with either of two different species of protozoa (Tetrahymena pyriformis or Colpoda steinii). During 7 d, δ15 N values increased in T. pyriformis while bacterial populations decreased. In a field test, following a 2.1-cm rainfall, 15 N-labeled E. coli, solutes (rhodamine WT dye and bromide), and latex microspheres were injected into a sinkhole approximately 530 m upgradient of a spring. Breakthrough of all tracers coincided, but microspheres were remobilized by subsequent storms, unlike other tracers. Enriched E. coli exhibited more tailing than solute tracers during the initial storm-flow recession. These results indicate that 15 N-enriched E. coli is a viable tracer of bacterial transport in karst aquifers, although predation may attenuate the isotopic signal in systems that are not rapidly flushed.

African Americans' perceptions of access to workplace opportunities: a survey of employees in Houston, Texas.

Although increasing numbers of African Americans are employed in predominantly white organizations, anecdotal and scholarly evidence suggests that they still must overcome barriers to have similar career trajectories as their white counterparts. This study is motivated by other studies pertaining to racial discrimination and inequalities at the workplace as experienced by blacks. We examined how African Americans perceive their own access to workplace opportunities and rewards, their views of other minority employees' work remuneration and career trajectory, as well as gender bias in their organizations. The findings indicated that many respondents believed that in crucial areas of job advancement (e.g., advanced training, mentoring, and promotion), they do not receive what they consider to be a fair share of opportunities from their organizations. Some respondents felt that other minority employees receive more attention and favorable treatment at work than they do. Considering gender bias, many thought that women of all ethnicities had more access to work benefits than their male counterparts.

Haptic feedback can provide an objective assessment of arthroscopic skills.

UNLABELLED: The outcome of arthroscopic procedures is related to the surgeon's skills in arthroscopy. Currently, evaluation of such skills relies on direct observation by a surgeon trainer. This type of assessment, by its nature, is subjective and time-consuming. The aim of our study was to identify whether haptic information generated from arthroscopic tools could distinguish between skilled and less skilled surgeons. A standard arthroscopic probe was fitted with a force/torque sensor. The probe was used by five surgeons with different levels of experience in knee arthroscopy performing 11 different tasks in 10 standard knee arthroscopies. The force/torque data from the hand and tool interface were recorded and synchronized with a video recording of the procedure. The torque magnitude and patterns generated were analyzed and compared. A computerized system was used to analyze the force/torque signature based on general principles for quality of performance using such measures as economy in movement, time efficiency, and consistency in performance. The results showed a considerable correlation between three haptic parameters and the surgeon's experience, which could be used in an automated objective assessment system for arthroscopic surgery. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Immersive visualization training of radiotherapy treatment.

External radiation beam treatment of cancer tumours involves delivery of invisible radiation beams through the body where internal structures can not be seen. Beam targeting of patient anatomy has to very accurate to achieve the desired therapeutic result. Good understanding of radiotherapy treatment (RT) concepts is essential to training. This paper presents a virtual environment simulator developed by the authors for training and education of intensity modulated radiotherapy (IMRT) treatment of cancer. This simulator employs immersive visualization to provide a high fidelity spatial awareness of the complex relationships between tumour, organs at risk, treatment beam and radiation dose. All these visualization are provided by a 3D virtual environment based on the patient in a RT treatment room. Immersive visualization using this simulator is being used to train radiation oncologist and radiation physicists about radiotherapy treatment.

Enhanced stereographic x-ray images.

This project extends previous work on stereographic projection of 2D x-ray images and aims to overcome a number of problems, namely: confusing stereo cues; distortion between stereo pairs; and increased radiation exposure from additional x-ray images. Images are distortion corrected and a polygonal representation of a bone fitted to the x-ray image, to approximate the bone surface. The polygonal representation is rendered and blended with the x-ray image to add surface detail, without obscuring salient features within the original x-ray. A reduction in x-ray exposure by using a stereo pair of computer-generated polygonal bone images blended with a mono x-ray image is investigated. An experiment provides evidence that depth perception is increased with the inclusion of bone surface rendering, and is achievable with a mono x-ray image.