290 research outputs found
Modeling Vocal Fold Motion with a New Hydrodynamic Semi-Continuum Model
Vocal fold (VF) motion is a fundamental process in voice production, and is
also a challenging problem for direct numerical computation because the VF
dynamics depend on nonlinear coupling of air flow with the response of elastic
channels (VF), which undergo opening and closing, and induce internal flow
separation. A traditional modeling approach makes use of steady flow
approximation or Bernoulli's law which is known to be invalid during VF
opening. We present a new hydrodynamic semi-continuum system for VF motion. The
airflow is modeled by a quasi-one dimensional continuum aerodynamic system, and
the VF by a classical lumped two mass system. The reduced flow system contains
the Bernoulli's law as a special case, and is derivable from the two
dimensional compressible Navier-Stokes equations. Since we do not make steady
flow approximation, we are able to capture transients and rapid changes of
solutions, e.g. the double pressure peaks at opening and closing stages of VF
motion consistent with experimental data. We demonstrate numerically that our
system is robust, and models in-vivo VF oscillation more physically. It is also
much simpler than a full two-dimensional Navier-Stokes system.Comment: 27 pages,6 figure
Ariel - Volume 6 Number 4 (Alternate Version)
Editors
Mark Dembert
J.D. Kanofsky
Frank Chervenak
John Lammie
Curt Cummings
Entertainment
Robert Breckenridge
Joe Conti
Gary Kaskey
Photographer
Larry Glazerman
Overseas Editor
Mike Sinason
Humorist
Jim McCann
Staff
Kenn Jaffe
Bob Sklaroff
Halley Faust
Jim Burke
Jay Amsterdam
Morton A. Klein
Nancy Redfer
Nature of orchestral noise
Professional orchestral musicians are at risk of exposure to excessive noise when at work. This is an industry-wide problem that threatens not only the hearing of orchestral musicians but also the way orchestras operate. The research described in this paper recorded noise levels within a professional orchestra over three years in order to provide greater insight to the orchestral noise environment; to guide future research into orchestral noise management and hearing conservation strategies; and to provide a basis for the future education of musicians and their managers. Every rehearsal, performance, and recording from May 2004 to May 2007 was monitored, with the woodwind, brass, and percussion sections monitored in greatest detail. The study recorded dBALEQ and dBC peak data, which are presented in graphical form with accompanying summarized data tables. The findings indicate that the principal trumpet, first and third horns, and principal trombone are at greatest risk of exposure to excessive sustained noise levels and that the percussion and timpani are at greatest risk of exposure to excessive peak noise levels. However, the findings also strongly support the notion that the true nature of orchestral noise is a great deal more complex than this simple statement would imply
A randomised pilot Phase II study of doxorubicin and cyclophosphamide (AC) or epirubicin and cyclophosphamide (EC) given 2 weekly with pegfilgrastim (accelerated) vs 3 weekly (standard) for women with early breast cancer
Accelerated (dose-dense) chemotherapy, in which the frequency of administration is increased without changing total dose or duration, may increase the efficacy of cancer chemotherapy. We performed a randomised Phase II study to assess the safety and relative toxicity of AC (doxorubicin; cyclophosphamide) vs E(epirubicin)C given by conventional or accelerated schedules as neoadjuvant or adjuvant chemotherapy for early breast cancer. Furthermore, the relative toxicity of doxorubicin and epirubicin remains uncertain. Patients were randomised to one of four arms; four courses of standard 3 weekly cyclophosphamide 600 mg m−2 in combination with doxorubicin 60 mg m−2 (AC) vs epirubicin 90 mg m−2 (EC) 3 weekly vs the same regimens administered every 2 weeks with pegfilgrastim (G-CSF). A total of 126 patients were treated, 42 with standard AC, 42 with accelerated AC, 19 with standard EC and 23 with accelerated EC. Significantly more grade 3/4 day one neutropenia was seen with standard (6/61, 10%) compared to accelerated (0/65,) regimens (P=0.01). A trend towards more neutropenic sepsis was seen in the combined standard and accelerated AC arms (12/84, 14%) compared to the combined EC arms (1/42, 2%), P=0.06. Falls in left ventricular ejection fraction were not increased with accelerated treatment. Accelerated AC and EC with pegfilgrastim are safe and feasible regimens in the treatment of early breast cancer with less neutropenia than conventional 3 weekly schedules
Pathological complete response and residual DCIS following neoadjuvant chemotherapy for breast carcinoma
Patients who have no residual invasive cancer following neoadjuvant chemotherapy for breast carcinoma have a better overall survival than those with residual disease. Many classification systems assessing pathological response to neoadjuvant chemotherapy include residual ductal carcinoma in situ (DCIS) only in the definition of pathological complete response. The purpose of this study was to investigate whether patients with residual DCIS only have the same prognosis as those with no residual invasive or in situ disease. A retrospective analysis of a prospectively maintained database identified 435 patients, who received neoadjuvant chemotherapy for operable breast cancer between February 1985 and February 2003. Of these, 30 (7%; 95% CI 5–9%) had no residual invasive disease or DCIS and 20 (5%; CI 3–7%) had residual DCIS only. With a median follow-up of 61 months, there was no statistical difference in disease-free survival, 80% (95% CI 60–90%) in those with no residual invasive or in situ disease and 61% (95% CI 35–80%) in those with DCIS only (P=0.4). No significant difference in 5-year overall survival was observed, 93% (95% CI 75–98%) in those with no residual invasive or in situ disease and 82% (95% CI 52–94%) in those with DCIS only (P=0.3). Due to the small number of patients and limited number of events in each group, it is not possible to draw definitive conclusions from this study. Further analyses of other databases are required to confirm our finding of no difference in disease-free and overall survival between patients with residual DCIS and those with no invasive or in situ disease following neoadjuvant chemotherapy for breast cancer
Effectiveness of an Intervention to Increase Construction Workers' Use of Hearing Protection
In this project we tested the effectiveness of a theory-based intervention (video, pamphlets, and guided practice session) to increase the use of hearing protection devices (HPDs) among Midwestern construction workers and a national group of plumber/pipefitter trainers. Posttest measures were collected 10--12 months following this intervention. Pender's Health Promotion Model (1987) provided the conceptual basis for development of the training program. A total of 837 highnoise- exposed workers were included in the analysis: 652 regional Midwestern construction workers and 185 national plumber/pipefitter trainers. Effectiveness of the intervention was determined through the sequence of analyses recommended by Braver and Braver (1988) for the Solomon Four-Group Design. Analysis of variance and covariance of postintervention use and intention to use HPDs and a meta-analytic test were done. These analyses indicated that the intervention significantly increased use of HPDs but had no effect on intention to use HPDs in the future. Pretesting had no effect on use. Actual or potential applications of this research include guidance in the development of successful theorybased interventions to increase use of HPDs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68025/2/10.1518_001872099779610969.pd
Hearing effects from intermittent and continuous noise exposure in a study of Korean factory workers and firefighters
<p>Abstract</p> <p>Background</p> <p>South Korea and surrounding countries in East Asia are believed to have the highest proportion in the world of high frequency hearing loss due to occupational noise exposure, yet there has been limited information published in international journals, and limited information for control of noise in local workplaces beyond strategies from western countries. We exploit medical surveillance information from two worker groups to enhance local knowledge about noise-induced hearing loss and explore the possible importance of shift work to risk.</p> <p>Methods</p> <p>Four-years of hearing data were evaluated for 81 male farm machine factory workers and 371 male firefighters who had successfully completed a health examination and questionnaires for the duration of the study period. The averages of hearing thresholds at 2, 3, and 4 kHz were used as the primary end-point for comparison. Repeat measure analysis adjusted for age, exposure duration and smoking status was used to measure the difference in hearing threshold between the two groups.</p> <p>Results</p> <p>Noise levels were measured in the factory at a mean of 82 dBA, with a range of 66-97. No concurrent measurements were taken for the firefighters, but historic comparison values showed a wider range but a similar mean of 76-79 dBA. Although losses during follow-up were negligible, the factory workers had significantly (<it>P </it>< 0.0001) more hearing loss at the baseline of the study than the firefighters in both ears at 2, 3, and 4 kHz, adjusted for age, duration of employment and smoking status. Among those with 10 years of employment, mean losses at these frequencies among the factory workers fell into the impairment range (> 25 dB loss). Firefighters also showed increased losses associated with longer exposure duration, but these were significantly less marked. Losses at lower frequencies (< or = 1 kHz) were negligible in both groups.</p> <p>Conclusions</p> <p>Korean work environments with continuous noise exposure in the measured range should consider implementation of a hearing conservation program. Further evaluation of hearing loss in workers exposed to irregular or intermittent high noise levels, such as firefighters, is also warranted.</p
Molecular alterations in key-regulator genes among patients with T4 breast carcinoma
Background: Prognostic factors in patients who are diagnosed with T4 breast carcinomas are widely awaited. We
here evaluated the clinical role of some molecular alterations involved in tumorigenesis in a well-characterized
cohort of T4 breast cancer patients with a long follow-up period.
Methods: A consecutive series of 53 patients with T4 breast carcinoma was enrolled between 1992 and 2001 in
Sardinia, and observed up for a median of 125 months. Archival paraffin-embedded tissue sections were used for
immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) analyses, in order to assess alterations in expression levels of survivin, p53, and pERK1-2 proteins as well as in amplification of CyclinD1 and h-prune genes.
The Kaplan-Meier and Cox regression methods were used for survival assessment and statistical analysis.
Results: Overall, patients carrying increased expression of pERK1-2 (p = 0.027) and survivin (p = 0.008) proteins as
well as amplification of h-prune gene (p = 0.045) presented a statistically-significant poorer overall survival in comparison with cases found negative for such alterations. After multivariate analysis, the pathological response to primary chemotherapy and the survivin overexpression in primary carcinoma represented the main parameters with a role as independent prognostic factors in our series.
Conclusions: Although retrospective, our study identified some molecular parameters with a significant impact on prediction of the response to therapy or prognosis among T4 breast cancer patients. Further large prospective studies are needed in order to validate the use of such markers for the management of these patients
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