Steven J. Pierce

Object identification without foveal vision: Evidence from an artificial scotoma paradigm

The purpose of the present study was to investigate the degree to which foveal information is necessary for object identification. To explore this question, we used an artificial moving scotoma paradigm to eliminate a region of a currently viewed display in real time as a function of eye position. Subjects examined linear arrays of four line drawings of objects while their eye movements were recorded. Immediately following each array, a test probe was presented to test the degree to which the subject had identified those objects. Three conditions were compared, one in which a central foveal scotoma was created, one in which an extrafoveal scotoma was created, and a control condition in which the scotoma was absent. The main result was that identification accuracy was very good, but eye-movement behavior was disrupted when a foveal scotoma was present. These results suggest that foveal information is not necessary but is beneficial for perceptual encoding during object identification; the loss of foveal information can be overcome as long as compensatory extrafoveal processing is possible.

Who Participates and Why: Building a Process Model of Citizen Participation

Initiating and sustaining sufficient levels of participation among residents in low-income and urban neighborhoods have become significant focuses of many initiatives that strive to develop healthy communities. This study examines the factors associated with citizen participation levels in resident leaders and followers in seven low-income neighborhoods in one community. Overall, the findings suggest that different factors facilitate participation in leaders and followers. Leaders are more likely to actively participate in neighborhood and community affairs if they perceive themselves as having the skills needed to organize others and make change happen. Whereas perceived skill levels also matter for followers, these residents are strongly influenced by the norms for activism within their neighborhood. These norms mediate the impact of neighborhood readiness and capacity for change on citizen participation levels. Implications for funders and practitioners interested in promoting healthy communities are discussed.

Climate and Landscape Factors Associated with Buruli Ulcer Incidence in Victoria, Australia

Background Buruli ulcer (BU), caused by Mycobacterium ulcerans (M. ulcerans), is a necrotizing skin disease found in more than 30 countries worldwide. BU incidence is highest in West Africa; however, cases have substantially increased in coastal regions of southern Australia over the past 30 years. Although the mode of transmission remains uncertain, the spatial pattern of BU emergence in recent years seems to suggest that there is an environmental niche for M. ulcerans and BU prevalence. Methodology/Principal Findings Network analysis was applied to BU cases in Victoria, Australia, from 1981–2008. Results revealed a non-random spatio-temporal pattern at the regional scale as well as a stable and efficient BU disease network, indicating that deterministic factors influence the occurrence of this disease. Monthly BU incidence reported by locality was analyzed with landscape and climate data using a multilevel Poisson regression approach. The results suggest the highest BU risk areas occur at low elevations with forested land cover, similar to previous studies of BU risk in West Africa. Additionally, climate conditions as far as 1.5 years in advance appear to impact disease incidence. Warmer and wetter conditions 18–19 months prior to case emergence, followed by a dry period approximately 5 months prior to case emergence seem to favor the occurrence of BU. Conclusions/Significance The BU network structure in Victoria, Australia, suggests external environmental factors favor M. ulcerans transmission and, therefore, BU incidence. A unique combination of environmental conditions, including land cover type, temperature and a wet-dry sequence, may produce habitat characteristics that support M. ulcerans transmission and BU prevalence. These findings imply that future BU research efforts on transmission mechanisms should focus on potential vectors/reservoirs found in those environmental niches. Further, this study is the first to quantitatively estimate environmental lag times associated with BU outbreaks, providing insights for future transmission investigations.

Identifying HIV prevention service needs of African American men who have sex with men: an application of spatial analysis techniques to service planning.

BACKGROUND Black men who have sex with men (MSM) are a priority population for HIV prevention. METHOD We applied spatial analysis techniques to map the availability of HIV prevention services to young black MSM in Chicago to guide prevention planning. GIS was used to map characteristics of ZIP codes in Chicago. Choropleth maps and descriptive statistics were used to visualize and analyze the data. RESULTS Areas where young black MSM reside typically have low HIV service densities. HIV service density also corresponds poorly to some ZIP codes in which young black MSM who report high rates of unprotected sexual behavior reside. CONCLUSION Spatial analysis can show whether services are located near specific populations of interest. Data from multiple sources can be integrated to explore relationships among characteristics of geographic zones.

Should Rape Kit Testing Be Prioritized by Victim–Offender Relationship?

Research Summary This study examined the DNA forensic testing outcomes from 894 previously untested sexual assault kits (SAKs) from Detroit, Michigan. At issue was how many of these SAKs would produce DNA profiles eligible for upload into CODIS (Combined DNA Index System), the national forensic DNA database maintained by the Federal Bureau of Investigation, and then how many would produce CODIS hits (DNA matches) to other crimes. Fifty-four percent of the SAKs associated with stranger-perpetrated sexual assaults yielded CODIS-eligible DNA profiles, producing 156 CODIS hits (DNA matches) and 51 hits matched prior sexual assault offenses in CODIS (i.e., serial sexual assault hit). Forty percent of the SAKs from nonstranger rapes had CODIS-eligible profiles, producing 103 CODIS hits and 18 serial sexual assault hits. CODIS entry rates and CODIS hit rates were equivalent between stranger and nonstranger SAKs; serial sexual assault hit rates were significantly higher for stranger SAKs. Policy Implications These results highlight the importance of testing both stranger and nonstranger SAKs as they have an equivalent likelihood of producing CODIS hits. The findings do not support policy recommendations that stranger-perpetrated SAKs should have testing priority over nonstranger SAKs. Prioritizing stranger SAKs may have unintended negative consequences on the utility of CODIS by limiting the number and type of eligible DNA profiles that are referenced in the federal DNA database.

Should Rape Kit Testing Be Prioritized by Victim-Offender Relationship?: Empirical Comparison of Forensic Testing Outcomes for Stranger and Nonstranger Sexual Assaults Campbell et al. Rape Kit Testing

Research Summary This study examined the DNA forensic testing outcomes from 894 previously untested sexual assault kits (SAKs) from Detroit, Michigan. At issue was how many of these SAKs would produce DNA profiles eligible for upload into CODIS (Combined DNA Index System), the national forensic DNA database maintained by the Federal Bureau of Investigation, and then how many would produce CODIS hits (DNA matches) to other crimes. Fifty-four percent of the SAKs associated with stranger-perpetrated sexual assaults yielded CODIS-eligible DNA profiles, producing 156 CODIS hits (DNA matches) and 51 hits matched prior sexual assault offenses in CODIS (i.e., serial sexual assault hit). Forty percent of the SAKs from nonstranger rapes had CODIS-eligible profiles, producing 103 CODIS hits and 18 serial sexual assault hits. CODIS entry rates and CODIS hit rates were equivalent between stranger and nonstranger SAKs; serial sexual assault hit rates were significantly higher for stranger SAKs. Policy Implications These results highlight the importance of testing both stranger and nonstranger SAKs as they have an equivalent likelihood of producing CODIS hits. The findings do not support policy recommendations that stranger-perpetrated SAKs should have testing priority over nonstranger SAKs. Prioritizing stranger SAKs may have unintended negative consequences on the utility of CODIS by limiting the number and type of eligible DNA profiles that are referenced in the federal DNA database.

Electromyographic activity of rectus capitis posterior minor muscles associated with voluntary retraction of the head.

BACKGROUND CONTEXT The functional role of rectus capitis posterior minor (RCPm) muscles is not well defined. To the best of our knowledge, electromyographic (EMG) data from RCPm muscles in humans have never been collected and analyzed. PURPOSE To test the null hypothesis that there will be no difference in normalized levels of EMG activity measured from RCPm muscles with the head in a neutral position and with the head in a retracted position. STUDY DESIGN A repeated measures design intended to quantify normalized levels of EMG activity measured from RCPm muscles. METHODS Disposable 25-gauge, bipolar fine wire hooked electrodes were used to collect EMG data from both right and left RCPm muscles from 17 asymptomatic subjects. Data were collected while subjects performed five trials with the head maintained in a neutral position; performed three maximal voluntary isometric contraction efforts; performed four trials with the head maintained in a retracted position. Mixed effects beta regression models were used to analyze the data. RESULTS Normalized EMG activity of RCPm muscles collected with the subjects head held in a retracted position was significantly higher (p<.0001) than normalized EMG activity collected with the subjects head held in a self-selected, neutral position. CONCLUSIONS Rectus capitis posterior minor muscles are active when the head is held in a neutral position and show a significant increase in activity when the head is held in a retracted position.

Parkinson's disease-associated genetic variation is linked to quantitative expression of inflammatory genes

Genome-wide association studies (GWAS) have linked dozens of single nucleotide polymorphisms (SNPs) with Parkinson’s disease (PD) risk. Ascertaining the functional and eventual causal mechanisms underlying these relationships has proven difficult. The majority of risk SNPs, and nearby SNPs in linkage disequilibrium (LD), are found in intergenic or intronic regions and confer risk through allele-dependent expression of multiple unknown target genes. Combining GWAS results with publicly available GTEx data, generated through eQTL (expression quantitative trait loci) identification studies, enables a direct association of SNPs to gene expression levels and aids in narrowing the large population of potential genetic targets for hypothesis-driven experimental cell biology. Separately, overlapping of SNPs with putative enhancer segmentations can strengthen target filtering. We report here the results of analyzing 7,607 PD risk SNPs along with an additional 23,759 high linkage disequilibrium-associated variants paired with eQTL gene expression. We found that enrichment analysis on the set of genes following target filtering pointed to a single large LD block at 6p21 that contained multiple HLA-MHC-II genes. These MHC-II genes remain associated with PD when the genes were filtered for correlation between GWAS significance and eQTL levels, strongly indicating a direct effect on PD etiology.

Activation of rectus capitis posterior major muscles during voluntary retraction of the head in asymptomatic subjects

OBJECTIVE The purpose of this study was to assess levels of electromyographic activity measured from rectus capitis posterior major (RCPM) muscles of asymptomatic subjects as their heads moved from a self-defined neutral position to a retracted position. METHODS A 2 × 2 within-subjects factorial research design was used. Disposable, intramuscular electrodes were used to collect electromyographic data from asymptomatic subjects between the ages of 20 and 40 years old. Data analysis was performed using mixed effects β regression models. RESULTS Activation of RCPM muscles was found to significantly increase (P < .0001) as the head moved from a self-defined neutral position to a retracted position. Rectus capitis posterior major muscle activation levels, measured as a function of head position, have not been previously reported. CONCLUSIONS The findings from this study showed that RCPM muscle activation significantly increases during voluntary retraction of the head.

Sex determination of human skeletal populations using latent profile analysis.

Accurately estimating biological sex from the human skeleton can be especially difficult for fragmentary or incomplete remains often encountered in bioarchaeological contexts. Where typical anatomically dimorphic skeletal regions are incomplete or absent, observers often take their best guess to classify biological sex. Latent profile analysis (LPA) is a mixture modeling technique which uses observed continuous data to estimate unobserved categorical group membership using posterior probabilities. In this study, sex is the latent variable (male and female are the two latent classes), and the indicator variables used here were eight standard linear measurements (long bone lengths, diaphyseal and articular breadths, and circumferences). Mplus (Muthén and Muthén: Mplus users guide, 6th ed. Los Angeles: Muthén & Muthén, 2010) was used to obtain maximum likelihood estimates for latent class membership from a known sample of individuals from the forensic data bank (FDB) (Jantz and Moore-Jansen: Database for forensic anthropology in the United States 1962-1991, Ann Arbor, MI: Interuniversity Consortium for Political and Social Research, 2000) (n = 1,831), yielding 87% of correct classification for sex. Then, a simulation extracted 5,000 different random samples of 206 complete cases each from the FDB (these cases also had known sex). We then artificially imposed patterns of missing data similar to that observed in a poorly preserved bioarchaeological sample from Medieval Asturias, Spain (n = 206), and ran LPA on each sample. This tested the efficacy of LPA under extreme conditions of poor preservation (missing data, 42%). The simulation yielded an average of 82% accuracy, indicating that LPA is robust to large amounts of missing data when analyzing incomplete skeletons.