Virtual acoustics displays

The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events

Documenting Nursing and Medical Students’ Stereotypes about Hispanic and American Indian Patients

Objective: Hispanic Americans and American Indians face significant health disparities compared with White Americans. Research suggests that stereotyping of minority patients by members of the medical community is an important antecedent of race and ethnicity-based health disparities. This work has primarily focused on physicians’ perceptions, however, and little research has examined the stereotypes healthcare personnel associate with Hispanic and American Indian patients. The present study assesses: 1) the health-related stereotypes both nursing and medical students hold about Hispanic and American Indian patients, and 2) nursing and medical students’ motivation to treat Hispanic and American Indian patients in an unbiased manner. Design: Participants completed a questionnaire assessing their awareness of stereotypes that healthcare professionals associate with Hispanic and American Indian patients then completed measures of their motivation to treat Hispanics and American Indians in an unbiased manner. Results: Despite being highly motivated to treat Hispanic and American Indian individuals fairly, the majority of participants reported awareness of stereotypes associating these patient groups with noncompliance, risky health behavior, and difficulty understanding and/or communicating health-related information. Conclusion: This research provides direct evidence for negative health-related stereotypes associated with two understudied minority patient groups—Hispanics and American Indians—among both nursing and medical personnel

Genetic dissection of MHC-associated susceptibility to Lepeophtheirus salmonis in Atlantic salmon

Background: Genetic variation has been shown to play a significant role in determining susceptibility to the salmon louse, Lepeophtheirus salmonis. However, the mechanisms involved in differential response to infection remain poorly understood. Recent findings in Atlantic salmon (Salmo salar) have provided evidence for a potential link between marker variation at the major histocompatibility complex (MHC) and differences in lice abundance among infected siblings, suggesting that MHC genes can modulate susceptibility to the parasite. In this study, we used quantitative trait locus (QTL) analysis to test the effect of genomic regions linked to MHC class I and II on linkage groups (LG) 15 and 6, respectively. Results: Significant QTL effects were detected on both LG 6 and LG 15 in sire-based analysis but the QTL regions remained unresolved due to a lack of recombination between markers. In dam-based analysis, a significant QTL was identified on LG 6, which accounted for 12.9% of within-family variance in lice abundance. However, the QTL was located at the opposite end of DAA, with no significant overlap with the MHC class II region. Interestingly, QTL modelling also revealed evidence of sex-linked differences in lice abundance, indicating that males and females may have different susceptibility to infection. Conclusion: Overall, QTL analysis provided relatively weak support for a proximal effect of classical MHC regions on lice abundance, which can partly be explained by linkage to other genes controlling susceptibility to L. salmonis on the same chromosom

Identifying Optimal Methods for Addressing Confounding Bias When Estimating the Effects of State-Level Policies

Background: Policy evaluation studies that assess how state-level policies affect health-related outcomes are foundational to health and social policy research. The relative ability of newer analytic methods to address confounding, a key source of bias in observational studies, has not been closely examined. Methods: We conducted a simulation study to examine how differing magnitudes of confounding affected the performance of four methods used for policy evaluations: (1) the two-way fixed effects (TWFE) difference-in-differences (DID) model; (2) a one-period lagged autoregressive (AR) model; (3) augmented synthetic control method (ASCM); and (4) the doubly robust DID approach with multiple time periods from Callaway-Sant'Anna (CSA). We simulated our data to have staggered policy adoption and multiple confounding scenarios (i.e., varying the magnitude and nature of confounding relationships). Results: Bias increased for each method: (1) as confounding magnitude increases; (2) when confounding is generated with respect to prior outcome trends (rather than levels), and (3) when confounding associations are nonlinear (rather than linear). The AR and ASCM have notably lower root mean squared error than the TWFE model and CSA approach for all scenarios; the exception is nonlinear confounding by prior trends, where CSA excels. Coverage rates are unreasonably high for ASCM (e.g., 100%), reflecting large model-based standard errors and wide confidence intervals in practice. Conclusions: Our simulation study indicated that no single method consistently outperforms the others. But a researcher's toolkit should include all methodological options. Our simulations and associated R package can help researchers choose the most appropriate approach for their data.Comment: 4 figures, 1 table, supplemental material including cod

Apportionment of primary and secondary organic aerosols in Southern California during the 2005 Study of Organic Aerosols in Riverside (SOAR-1)

Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionment techniques. The secondary organic aerosol (SOA) mass is estimated by elemental carbon and carbon monoxide tracer methods, water soluble organic carbon content, chemical mass balance of organic molecular markers, and positive matrix factorization of high-resolution aerosol mass spectrometer data. Estimates obtained from each of these methods indicate that the organic fraction in ambient aerosol is overwhelmingly secondary in nature during a period of several weeks with moderate ozone concentrations and that SOA is the single largest component of PM1 aerosol in Riverside. Average SOA/OA contributions of 70−90% were observed during midday periods, whereas minimum SOA contributions of ~45% were observed during peak morning traffic periods. These results are contrary to previous estimates of SOA throughout the Los Angeles Basin which reported that, other than during severe photochemical smog episodes, SOA was lower than primary OA. Possible reasons for these differences are discussed

The Gulf Stream Front, Its Role in Larval Fish Survival and Recruitment in Florida: Hydrographic Station and Plankton Data

The goal of this project was to develop a clearer understanding of the role that the Gulf Stream system plays in larval fish survival and recruitment in Florida waters. The specific objectives of this study were to: Determine whether the biomass of fish larva, other zooplankton, microzooplankton and phytoplankton is higher at the shoreward front of the Gulf Stream than on either side of it. Characterize the assemblages of fish larvae predators and prey both at the front and on either side of it. Determine if the composition, abundance and size frequency distribution of larval and juvenile fishes in the front is different from that in the coastal zone or in the Gulf Stream. Monitor the position of the Gulf Stream by continuous measurements of physical variables at moorings located in the Gulf Stream off Fort Lauderdale and within Port Everglades. This project was a first effort to characterize the coupling between physical and biological processes that may influence the early life histories of fishes in Florida\u27s coastal waters. This report contains the hydrographic and plankton data from the project. It is intended to facilitate data access by the scientific and management communities. Interpretations and detailed analyses of these data are being given in meeting presentations, peer-reviewed journal articles (Stone et al. draft manuscript, Braker et al. draft manuscript, Frazel et al. in preparation) and graduate theses (Stone 1993; Braker 1993)

Recognition of O6-benzyl-2′-deoxyguanosine by a perimidinone-derived synthetic nucleoside: a DNA interstrand stacking interaction

The 2′-deoxynucleoside containing the synthetic base 1-[(2R,4S,5R)-4-hydroxy-5-(hydroxymethyl)-tetrahydrofuran-2-yl)-1H-perimidin-2(3H)-one] (dPer) recognizes in DNA the O6-benzyl-2′-deoxyguanosine nucleoside (O6-Bn-dG), formed by exposure to N-benzylmethylnitrosamine. Herein, we show how dPer distinguishes between O6-Bn-dG and dG in DNA. The structure of the modified Dickerson-Drew dodecamer (DDD) in which guanine at position G4 has been replaced by O6-Bn-dG and cytosine C9 has been replaced with dPer to form the modified O6-Bn-dG:dPer (DDD-XY) duplex [5′-d(C1G2C3X4A5A6T7T8Y9G10C11G12)-3′]2 (X = O6-Bn-dG, Y = dPer) reveals that dPer intercalates into the duplex and adopts the syn conformation about the glycosyl bond. This provides a binding pocket that allows the benzyl group of O6-Bn-dG to intercalate between Per and thymine of the 3′-neighbor A:T base pair. Nuclear magnetic resonance data suggest that a similar intercalative recognition mechanism applies in this sequence in solution. However, in solution, the benzyl ring of O6-Bn-dG undergoes rotation on the nuclear magnetic resonance time scale. In contrast, the structure of the modified DDD in which cytosine at position C9 is replaced with dPer to form the dG:dPer (DDD-GY) [5′-d(C1G2C3G4A5A6T7T8Y9G10C11G12)-3′]2 duplex (Y = dPer) reveals that dPer adopts the anti conformation about the glycosyl bond and forms a less stable wobble pairing interaction with guanin

The Ames Virtual Environment Workstation: Implementation issues and requirements

This presentation describes recent developments in the implementation of a virtual environment workstation in the Aerospace Human Factors Research Division of NASA's Ames Research Center. Introductory discussions are presented on the primary research objectives and applications of the system and on the system's current hardware and software configuration. Principle attention is then focused on unique issues and problems encountered in the workstation's development with emphasis on its ability to meet original design specifications for computational graphics performance and for associated human factors requirements necessary to provide compelling sense of presence and efficient interaction in the virtual environment

Source apportionment of organic carbon in Centreville, AL using organosulfates in organic tracer-based positive matrix factorization

Organic tracer-based positive matrix factorization (PMF) was used to apportion fine particulate (PM_(2.5)) organic carbon (OC) to its sources in Centreville, AL, USA, a rural forested site influenced by anthropogenic emissions, during the Southern Oxidant and Aerosol Study (SOAS) in the summer of 2013. Model inputs included organosulfates, a group of organic compounds that are tracers of anthropogenically-influenced biogenic secondary organic aerosols (SOA), as well as, OC, elemental carbon, water-soluble organic carbon, and other organic tracers for primary and secondary sources measured during day and night. The organic tracer-based PMF resolved eight factors that were identified as biomass burning (11%, average contribution to PM_(2.5) OC), vehicle emissions (8%), isoprene SOC formed under low-NO_x conditions (13%), isoprene SOC formed under high-NO_x conditions (11%), SOC formed by photochemical reactions (9%), oxidatively aged biogenic SOC (6%), sulfuric acid-influenced SOC (21%, that also includes isoprene and monoterpene SOC), and monoterpene SOC formed under high-NO_x conditions (21%). These results indicate that OC in Centreville during summer is mainly secondary in origin (81%). Fossil fuel combustion is the major source of NO_x, ozone, and sulfuric acid that play a key role in SOA formation in the southeastern US. Fossil fuel was found to influence 61–76% of OC through vehicle emissions and SOA formation. Together with prescribed burns, which were the major type of biomass burning during this study, the OC influenced by anthropogenic activities reached 87%. The organic tracer-based PMF results were further compared with two complementary source apportionment techniques: PMF factors resolved for submicron organic aerosols measured using aerosol mass spectrometry (AMS) by Xu et al. (2015a) in Centreville during SOAS; biomass burning organic aerosols (BBOA, 11% of OC), isoprene-derived organic aerosols (isoprene-OA, 20% of OC), more-oxidized oxygenated organic aerosols (MO-OOA, 34% of OC), and less-oxidized oxygenated organic aerosols (LO-OOA, 35% of OC); and PM_(2.5) OC apportioned by chemical-mass balance model (CMB), considering the same chemical species as this study, save for organosulfates; biomass burning (5%), diesel engines (2%), gasoline smokers (3%), vegetative detritus (1%), isoprene SOC (23%) and monoterpene SOC (34%), and other (likely biogenic secondary) sources (33%). Overall, this study indicates the primary and secondary sources resolved by the organic tracer-based PMF are in good agreement with CMB and AMS-PMF results, while the organic tracer-based PMF provides additional insight to the SOC formation pathways through the inclusion of organosulfates and other organic tracers measured during day and night