Functional anatomy of the masking level difference, an fMRI study

Introduction: Masking level differences (MLDs) are differences in the hearing threshold for the detection of a signal presented in a noise background, where either the phase of the signal or noise is reversed between ears. We use N0/Nπ to denote noise presented in-phase/out-of-phase between ears and S0/Sπ to denote a 500 Hz sine wave signal as in/out-of-phase. Signal detection level for the noise/signal combinations N0Sπ and NπS0 is typically 10-20 dB better than for N0S0. All combinations have the same spectrum, level, and duration of both the signal and the noise. Methods: Ten participants (5 female), age: 22-43, with N0Sπ-N0S0 MLDs greater than 10 dB, were imaged using a sparse BOLD fMRI sequence, with a 9 second gap (1 second quiet preceding stimuli). Band-pass (400-600 Hz) noise and an enveloped signal (.25 second tone burst, 50% duty-cycle) were used to create the stimuli. Brain maps of statistically significant regions were formed from a second-level analysis using SPM5. Results: The contrast NπS0- N0Sπ had significant regions of activation in the right pulvinar, corpus callosum, and insula bilaterally. The left inferior frontal gyrus had significant activation for contrasts N0Sπ-N0S0 and NπS0-N0S0. The contrast N0S0-N0Sπ revealed a region in the right insula, and the contrast N0S0-NπS0 had a region of significance in the left insula. Conclusion: Our results extend the view that the thalamus acts as a gating mechanism to enable dichotic listening, and suggest that MLD processing is accomplished through thalamic communication with the insula, which communicate across the corpus callosum to either enhance or diminish the binaural signal (depending on the MLD condition). The audibility improvement of the signal with both MLD conditions is likely reflected by activation in the left inferior frontal gyrus, a late stage in the what/where model of auditory processing. © 2012 Wack et al

Vaginal Microbicide Preferences Among Midwestern Urban Adolescent Women

Purpose The purpose of this study was to assess adolescent women's preferences for specific microbicide characteristics including pregnancy prevention, timing of application, potential for side effects, and whether it targeted human immunodeficiency virus (HIV) or other sexually transmitted infections (STI). Potential differences in microbicide preferences by adolescent age group and behavioral patterns including engaging in sexual intercourse and use of hormonal contraception were examined, as it was hypothesized that as adolescents progress into adulthood and gain sexual experience their preferences in microbicide characteristics may shift. Method Adolescent and young women (N = 405, 56.0% African American; 24.0% Euro-American) between the ages of 14 and 20 (mean = 17.0, SD = 1.8) were recruited from urban community-based clinics. Video-Audio Computer-Assisted Self-Interviews were conducted with the young women, during which they were asked about their preferences regarding the characteristics of hypothetical vaginal microbicides. Conjoint analysis was utilized to determine adolescent women's relative preferences for each microbicide characteristic and intent-to-purchase microbicides based upon a combination of the selected properties. Results Overall, the results suggest adolescent and young women had an ordered preference for a microbicide with (1) no side effects, (2) pregnancy prevention, (3) postcoital application, and (4) protection against HIV. Age and behavioral group conjoint analyses resulted in the same pattern of preferences as those reported for the entire group. However, women having sex and not using hormonal contraception had a stronger preference for postcoital application. Conclusion The findings suggest that young women's ratings of microbicides were sensitive to characteristics such as side effects, pregnancy prevention, and timing of application and should be considered in microbicide development. The conjoint analysis approach is useful in understanding microbicide preferences, and should be utilized with other populations to assess preferences for specific microbicide characteristics

Mathematics Teacher Educators\u27 Exploring Self-Based Methodologies

Historically underused methodologies in mathematics teacher education such as narrative inquiry, self-study, and autoethnography (i.e., self-based methodologies) are becoming a more frequent choice of mathematics teacher educators (MTEs). This has opened new challenges for MTEs as they try to disseminate their findings in mathematics education journals. Building from our working group at PME-NA 2018, we respond to the need for creating spaces (communities) where MTEs can feel supported in their study design, implementation, representation of findings, and publication using self-based methodologies. This year, we shift our focus from discussion to mentoring and scholarship on self-based methodologies. We invite MTEs with research projects in any stage of preparation to join us to in discussions meant to promote growth, sustainability, and continued insight into the use of self-based methodologies

Differences in one-year health outcomes and resource utilization by definition of prolonged mechanical ventilation: a prospective cohort study

Abstract Introduction The outcomes of patients ventilated for longer than average are unclear, in part because of the lack of an accepted definition of prolonged mechanical ventilation (PMV). To better understand the implications of PMV provision, we compared one-year health outcomes between two common definitions of PMV as well as between PMV patients and those ventilated for shorter periods of time. Methods We conducted a secondary analysis of prospectively collected data from medical and surgical intensive care units at an academic tertiary care medical center. The study included 817 critically ill patients ventilated for ≥ 48 hours, 267 (33%) of whom received PMV based on receipt of a tracheostomy and ventilation for ≥ 96 hours. A total of 114 (14%) patients met the alternate definition of PMV by being ventilated for ≥ 21 days. Survival, functional status, and costs were measured at baseline and at 2, 6, and 12 months after discharge. Of one-year survivors, 71 (17%) were lost to follow up. Results PMV patients ventilated for ≥ 21 days had greater costs ($140,409 versus$143,389) and higher one-year mortality (58% versus 48%) than did PMV patients with tracheostomies who were ventilated for ≥ 96 hours. The majority of PMV deaths (58%) occurred after hospital discharge whereas 67% of PMV patients aged 65 years or older had died by one year. At one year PMV patients on average had limitations in two basic and five instrumental elements of functional status that exceeded both their pre-admission status and the one-year disability of those ventilated for < 96 hours. Costs per one-year survivor were $423,596,$266,105, and $165,075 for patients ventilated ≥ 21 days, ≥ 96 hours with a tracheostomy, and < 96 hours, respectively. Conclusion Contrasting definitions of PMV capture significantly different patient populations, with ≥ 21 days of ventilation specifying the most resource-intensive recipients of critical care. PMV patients, particularly the elderly, suffer from a significant burden of costly, chronic critical illness and are at high risk for death throughout the first year after intensive care

Mathematics Teacher Educators Using Self-Based Methodologies

Narrative inquiry, self-study, and autoethnography (i.e., self-based methodologies) are becoming a more common choice of mathematics teacher educators (MTEs). This has opened new possibilities and challenges for early career MTEs as they try to disseminate their findings in mathematics education journals. Building from our working group at PME-NA 2018 and 2019, we respond to the need for creating a community where MTEs can feel supported in their study design, implementation, representation of findings, and publication using self-based methodologies. This year, we continue our focus on mentoring and scholarship on self-based methodologies. We invite English- and Spanish-speaking MTEs with research projects in any stage of preparation to join us in discussions meant to promote growth, sustainability, and continued insight into the use of self-based methodologies

Revision of Paschen's Law Relating to the ESD of Aerospace Vehicle Surfaces

The purpose of this work is to develop a version of Paschens law that takes into account the flow of ambient gas past electrode surfaces. Paschens law does not consider the flow of gas past an aerospace vehicle whose surfaces may be triboelectrically charged by dust or ice crystal impingement while traversing the atmosphere. The basic hypothesis of this work is that the number of electron-ion pairs created per unit distance between electrode surfaces is mitigated by the electron-ion pairs removed per unit distance by the flow of gas. The revised theoretical model must be a function of the mean velocity vxm of the ambient gas and reduce to Paschens law when the mean velocity is zero. A new theoretical formulation of Paschens law, taking into account the Mach number and compressible dynamic pressure, derived by the authors, will be discussed. This equation has been evaluated by wind tunnel experimentation. Initial data of the baseline wind tunnel experiments show results consistent with the hypothesis. This work may enhance the safety of aerospace vehicles through a redefinition of electrostatic launch commit criteria. It is also possible for new products, such as antistatic coatings, to be formulated based on this data

Dynamic Gas Flow Effects on the ESD of Aerospace Vehicle Surfaces

The purpose of this work is to develop a dynamic version of Paschen's Law that takes into account the flow of ambient gas past aerospace vehicle surfaces. However, the classic Paschen's Law does not take into account the flow of gas of an aerospace vehicle, whose surfaces may be triboelectrically charged by dust or ice crystal impingement, traversing the atmosphere. The basic hypothesis of this work is that the number of electron-ion pairs created per unit distance by the electric field between the electrodes is mitigated by the electron-ion pairs removed per unit distance by the flow of gas. The revised Paschen equation must be a function of the mean velocity, v(sub xm), of the ambient gas and reduces to the classical version of Paschen's law when the gas mean velocity, v(sub xm) = 0. New formulations of Paschen's Law, taking into account Mach number and dynamic pressure, derived by the authors, will be discussed. These equations will be evaluated by wind tunnel experimentation later this year. Based on the results of this work, it is hoped that the safety of aerospace vehicles will be enhanced with a redefinition of electrostatic launch commit criteria. It is also possible that new products, such as new anti-static coatings, may be formulated from this data