A Reanalysis of the Voicing Effect in English: With Implications for Featural Specification.

The voicing effect is among the most studied and robust of phonetic phenomena. Yet there remains a lack of consensus on why vowels preceding voiced obstruents should be longer than vowels preceding voiceless obstruents. In this paper we provide an analysis of the voicing effect in a corpus of natural speech, and using production data from a metronome-timed word repetition study. From this evidence, as well as the existing literature, we conclude that vowel duration differences follow from consonant duration differences. The characteristic voicing effect in English is largely limited to words of especially long duration, and preceding vowel duration does not reliably cue obstruent voicing under the following circumstances: when obstruent voicing or duration cues conflict; for lax or unstressed vowels; and for most conversational speech. We show that this behavior can be modeled using a competing-constraints framework, where all segments resist expanding or compressing past a preferred duration. Inherent segment elasticity determines the degree of resistance, but segment duration is ultimately determined by the interaction of these segmental constraints with constraints on the distribution of the lengthening force within the syllable, and how closely target durations are matched. This account of the voicing effect has a number of implications for phonological theory, especially the central role that the concept of prominence plays in the analysis of underlying features.

Implications of an exemplar-theoretic model of phoneme genesis: a velar palatalization case study.

Diachronic velar palatalization is taken as the case study for modeling the emergence of a new phoneme category. The spread of a palatalized variant through the lexicon is treated as a stochastic classification task for the listener/learner. The model combines two measures of similarity to determine classification within an exemplar-theoretic framework: acoustic distance and phonotactic expectation. There are three model outcomes: contrast, allophony, or contextual neutralization between the plain and palatalized velars. It is shown, through a series of simulations, that these can be predicted from the distribution of sounds within the pre-change lexicons, namely, the ratio of the /k-vowel/ sequences containing naturally palatalizing vowels (i, I, e), to those containing non-palatalizers. "Unnatural" phonotactic associations can arise in individual lexicons, but are sharply limited due to the large size of the lexicon and the local nature of the phoneme changes. "Anti-natural" distributions, which categorically violate the proposed implicational relationship between palatalization and frontness/height, are absent. This work provides an explicit and restrictive model of phoneme change. The results also serve as an existence proof for an outcome-blind mechanism of avoiding over-generation.

A systematic review of housing interventions and health: introduction, methods, and summary findings.

Subject matter experts systematically reviewed evidence on the effectiveness of specific housing interventions in improving health. The panelists reviewed housing interventions associated with exposure to biological and chemical agents, structural injury hazards, and community-level interventions. Intervention studies were grouped together according to recommendations in the Guide to Community Preventive Services, which identifies similarities in the type of intervention, its delivery and setting, and the target population. Review panelists found that 11 interventions had sufficient evidence of effectiveness, 15 required more field evaluation, 19 needed formative research, and 7 either had no evidence of effectiveness or were ineffective. Although many housing conditions are associated with adverse health outcomes, sufficient evidence now shows that specific housing interventions can improve certain health outcomes. The results of these evidence reviews can inform a robust agenda for widespread implementation and further research. This article highlights the project's research methods and summary findings, and its companion articles detail the evidence reviews for specific housing interventions.

Housing interventions at the neighborhood level and health: a review of the evidence.

A panel of subject matter experts systematically reviewed evidence linking neighborhood-level housing interventions, such as housing programs or policies, to health outcomes. One of the 10 interventions reviewed--the Housing Choice Voucher Program--had sufficient evidence for implementation or expansion. The evidence showed that voucher holders are less likely to suffer from overcrowding, malnutrition due to food insecurity, and concentrated neighborhood poverty than non-voucher holders. Of the other reviewed interventions, 2 needed more field evaluation and 7 needed more formative research. None were determined to be ineffective. Although many of the reviewed interventions lacked sufficient evidence for widespread implementation solely based on their health benefits, this evidence review shows that many interventions positively affect other areas of social, economic, and environmental well-being. Efforts to improve neighborhood environments and to maintain and increase the number of affordable housing units are critical to ensuring safe, healthy, and affordable housing for all people in the United States. Given that people of color disproportionately reside in high-poverty neighborhoods, neighborhood-level interventions may be particularly important in efforts to eliminate health disparities.

Mold and endotoxin levels in the aftermath of Hurricane Katrina: a pilot project of homes in New Orleans undergoing renovation.

BACKGROUND: After Hurricane Katrina, many New Orleans homes remained flooded for weeks, promoting heavy microbial growth. OBJECTIVES: A small demonstration project was conducted November 2005-January 2006 aiming to recommend safe remediation techniques and safe levels of worker protection, and to characterize airborne mold and endotoxin throughout cleanup. METHODS: Three houses with floodwater lines between 0.3 and 2 m underwent intervention, including disposal of damaged furnishings and drywall, cleaning surfaces, drying remaining structure, and treatment with a biostatic agent. We measured indoor and outdoor bioaerosols before, during, and after intervention. Samples were analyzed for fungi [culture, spore analysis, polymerase chain reaction (PCR)] and endotoxin. In one house, realtime particle counts were also assessed, and respirator-efficiency testing was performed to establish workplace protection factors (WPF). RESULTS: At baseline, culturable mold ranged from 22,000 to 515,000 colony-forming units/m3, spore counts ranged from 82,000 to 630,000 spores/m3, and endotoxin ranged from 17 to 139 endotoxin units/m3. Culture, spore analysis, and PCR indicated that Penicillium, Aspergillus, and Paecilomyces predominated. After intervention, levels of mold and endotoxin were generally lower (sometimes, orders of magnitude). The average WPF against fungal spores for elastomeric respirators was higher than for the N95 respirators. CONCLUSIONS: During baseline and intervention, mold and endotoxin levels were similar to those found in agricultural environments. We strongly recommend that those entering, cleaning, and repairing flood-damaged homes wear respirators at least as protective as elastomeric respirators. Recommendations based on this demonstration will benefit those involved in the current cleanup activities and will inform efforts to respond to future disasters.