bluuebunny/crossref_metadata_2025 huggingface dataset:
Effectiveness of the “Baby Think It Over” Teen Pregnancy Prevention Program
Authors: Somers Cheryl L. , Fahlman Mariane M.
Published: October 2009

ABSTRACT: In an effort to reduce teen pregnancy, schools are purchasing a program called “Baby Think It Over,” a computerized infant simulator intended to provide a realistic infant care experience. However, little empirical, especially experimental, program effectiveness data exist. This study determined if the program changed participants' attitudes toward parenting, as well as sexual and contraceptive behaviors linked to avoidance of teen pregnancy. Development of measurement tools was a part of the purpose. The study also asked teen‐agers, through narrative questions, about their conscious perceptions of the baby's utility and impact. Participants included experimental (n = 151) and control (n = 62) groups of primarily White, middle class, suburban high school students (mean age = 16.2). The quasi‐experimental portion of the study failed to reveal a statistically significant effect. Narrative data revealed several positive and notable program effects.
Self‐Reported School Difficulties and Tobacco Use Among Fourth‐ to Seventh‐Grade Students
Authors: Lee David J. , Trapido Edward , Rodriguez Richard
Published: October 2009

ABSTRACT: This study examined the relationship between academic and behavioral difficulties at school, and tobacco use in students. Participants included 1,219 students in fourth to seventh grade at the time of enrollment. Interviews were repeated eight months later with 85% of baseline participants. Telephone interviews assessed use of cigarettes, cigars, and chewing tobacco; students also were asked if they liked school, how often they got in trouble at school, and how well they were doing in school. At baseline, students reporting school difficulties were 1.4 – 5.6 times more likely to report a lifetime history of cigarette, cigar, and chewing tobacco use relative to students who did not report these difficulties. Average to below‐average academic performance at baseline was predictive of new cigarette use at the eight‐month follow‐up (Relative Risk = 3.35; 95% Confidence Interval = [1.36, 8.22]). Self‐reported school difficulties are associated with lifetime use of all major forms of tobacco and are predictive of future cigarette use in fourth‐ to seventh‐grade students.
Opinions of Illinois Voters About Coordinated School Health Programs
Authors: Temple Mark A.
Published: October 2009

ABSTRACT: A random‐digit dialed telephone survey was conducted in Illinois to determine support for coordinated school health programs (CSHP). Survey data were obtained from 469 registered voters in June and July 2000. Results demonstrated that most Illinois registered voters: 1) supported the concept and practice of CSHP; 2) were uncertain if current school health education and services were adequate; 3) believed Illinois schools should set a goal of creating a “healthier state;” and 4) although supportive of concept, were not familiar with term CSHP. Characteristics of supportive and nonsupportive registered voters are reported. Results of this study may assist in developing educational and marketing strategies to build support for coordinated school health programs in Illinois. (J Sch Health. 2002;72(1):8–12)
Factors Influencing the Performance of Volunteers Who Provide Physical Activity in Middle Schools
Authors: Strelow Jamie S. , Larsen Judith S. , Sallis James F. , Conway Terry L. , Powers Holly S. , McKenzie Thomas L.
Published: October 2009

ABSTRACT: Increasing physical activity among youth represents a national health goal, and using volunteer activity providers at schools offers one possible solution. This paper describes results from a program to recruit volunteer physical activity providers in middle schools. Twenty‐one volunteers provided 850 physical activity hours at seven schools, including 575 activity sessions and 7,186 student contacts. Volunteers who received incentives offered more minutes of activity, conducted more activity sessions, reached a greater number of students, and logged more student‐minutes of physical activity than those who received none. Male volunteers provided more activity minutes than female volunteers, but females were marginally more successful in engaging female students. Results can help guide schools to more effectively increase student physical activity throughout the school day. (J Sch Health 2002;72(4):147–151)
The Alcohol‐Related Psychosocial and Behavioral Risks of a Nationally Representative Sample of Adolescents
Authors: Maney Dolores W. , Higham‐Gardill D. A. , Mahoney Beverly S.
Published: October 2009

ABSTRACT: This study, a secondary analysis of the National Longitudinal Study of Adolescent Health, used a representative sample of 7th‐ through 12th‐grade students enrolled in US public schools between April and December 1995. Data were collected in respondents' homes using trained interviewers. A subset of 4,485 adolescents aged 12–17 were surveyed with regard to alcohol‐use practices and related health‐risk behavior, interpersonal problems, and demographic characteristics. Results showed adolescent males as significantly more likely to drink at high risk than adolescent females. Among those who drank one or more times in the past year, older adolescents were significantly more likely to report high‐risk drinking than younger adolescents. Significantly more high‐risk adolescents reported having a hangover, vomiting, regretting a behavior, having trouble with parents, regretting a sexual activity, having dating problems, fighting, having trouble with friends, and experiencing school trouble than did low‐risk adolescents. These findings underscore the long‐range significance of a coordinated school health program; in particular, school health services, school health instruction, and school health environment. Implications for school‐based and community‐based prevention and intervention programs are presented.
Evaluation of a Theater Production About Eating Behavior of Children
Authors: Perry Cheryl L. , Zauner Marguerite , Oakes J. Michael , Taylor Gretchen , Bishop Donald B.
Published: October 2009

ABSTRACT: This study evaluated “All's Well That Eats Well,” a theater production performed in 20 schools in the Twin Cities, Minn., metropolitan area in winter 2000. The production sought to change food‐related knowledge and food choices concerning fruits and vegetables among children in grades 1–6. The study used a pretest‐posttest design with two randomly‐assigned, sequential intervention‐control groups (N = 4,093). All students completed surveys prior to and then following the theater production and the classroom and home activities. No differences existed between the groups at pretest. Significant differences occurred in food‐related knowledge, food choices, and food recall from pretest to posttest for all students. Significant differences also occurred between intervention groups in food‐related knowledge and food choices. The study indicates that professional theater productions in schools can create at least a short‐term effect on children's nutrition knowledge and behavior.
A Statewide School Tobacco Policy Review: Process, Results, and Implications
Authors: Stephens Yvonne D. , English Gary
Published: October 2009

ABSTRACT: The federal Pro‐Children's Act of 1994 and other public health laws prompted most schools to create policies that address tobacco issues. To date, however, the literature is devoid of research that assesses the quality of a district's tobacco policy. This article describes the process and results from a large‐scale, tobacco policy review. An Interagency Tobacco Task Group requested that tobacco policies of all New York State schools be reviewed. A policy rubric was developed using the documents Fit, Healthy, and Ready to Learn and the School Health Index. The rubric assessed five policy components. Aggregate data were calculated for each policy component and for the final score. School policies also were evaluated for compliance with state and federal laws. Overall policy review scores were quite low, suggesting greater effort be placed on helping schools to develop more effective tobacco policies. Initial efforts included sending letters and a “tobacco tool kit” to schools containing recommendations and resources to improve their district's tobacco policy.
A Meta‐Evaluation of 11 School‐Based Smoking Prevention Programs
Authors: Tingle Lynne R. , DeSimone Marie , Covington Benjamin
Published: October 2009

ABSTRACT: Eleven school‐based smoking prevention programs were subjected to a meta‐ evaluation. Criteria for the meta‐evalua‐tion included: 1) adequacy of the research design, 2) evidence of reliability, 3) evidence of validity, 4) appropriate statistical analyses and interpretations, 5) reporting of effect sizes or practical significance, 6) accounting for attrition, and 7) tracking of fidelity to the program. A three‐point rating scale was used ranging from 0 – 2. Criteria with the best ratings were research design and statistical analysis. The lowest ratings occurred for reliability and validity. The remainder of the criteria ranged between 1 and 2 with minor factors accounting for the difference in ratings. Recommendations include increasing the number of evaluations that included tests of reliability and validity and calculated effect size estimates.
Differences in Behavior, Psychological Factors, and Environmental Factors Associated with Participation in School Sports and Other Activities in Adolescence
Authors: Harrison Patricia A. , Narayan Gopalakrishnan
Published: October 2009

ABSTRACT: This study examined whether participation in school team sports, exclusively or in combination with other extracurricular activities, is associated with higher levels of psychosocial functioning and healthy behavior than participation in other extracurricular activities alone or nonparticipation. The study sample includes 50,168 ninth grade public school students who completed an anonymous, voluntary statewide survey in 2001. Students were classified into four groups based on their participation in sports and other activities (such as clubs, volunteer work, band, choir, or music lessons): neither, both, other activities only, and sports only. Odds ratios for the group involved in both types of activities were significantly higher than those for all the other groups for all healthy behaviors and measures of connectedness, and significantly lower for all but one of the unhealthy behaviors. Students involved in sports, alone or in combination with other activities, had significantly higher odds than the other two groups for exercise, milk consumption, and healthy self‐image, and significantly lower odds for emotional distress, suicidal behavior, family substance abuse, and physical and sexual abuse victimization. Students involved in other activities, alone or in combination with sports, had significantly higher odds than the other two groups for doing homework and significantly lower odds for alcohol consumption, mari‐juana use, and vandalism. The finding that abuse victims appeared to avoid sports but not other group activities raises concern and merits further research. Considering the potential benefits of participation in sports and other activities, more research is needed to identify and overcome barriers or deterrents, particularly for youth from low‐income families.
Feasibility of School‐Based Spirometry Screening for Asthma
Authors: Abramson Jill M. , Wollan Peter , Kurland Marge , Yawn Barbara P.
Published: October 2009

ABSTRACT: To determine the feasibility and value of spirometry in school‐based asthma screening, spirometry testing was coupled with parent questionnaires in a school‐based asthma screening project. Children in grades five to eight of the Catholic school system in Rochester, Minn., performed spirometry with coaching and data acquisition by nurses trained for this activity. Most students completed three tests. For each student, the best test was selected for interpretation. Tests were considered technically unacceptable for screening purposes if the FEVI was less than 85% and the curve showed evidence of cough, delayed start, poor initial effort, incomplete effort, or non‐reproducibility. Students with acceptable tests and FEVI <85% as predicted for age, race, and BMI were classified as appropriate for referral for further evaluation of potential asthma. A sensitivity analysis was conducted using different FEVI thresholds for referral. Children (119, 17.6% of all) with known asthma based on parent‐completed questionnaire were not considered for referral. Of the remaining 557 students screened, 535 had technically acceptable tests, and 498 had normal spirometry performance. Using a threshold for referral of FEVI <85%, 37 children were candidates for referral for further evaluation of potential asthma. Only four (11%) of these also had questionnaire responses that made them candidates for referral. School‐based spirometry screening for asthma is technically feasible but there is little overlap between those who are referral candidates based on spirometry data and those who are referral candidates based on parent‐reported symptoms on screening questionnaires. Without further study, spirometry cannot be recommended for school‐based asthma screening.
Symptoms of Nicotine Dependence and Other Predictors of Student Smoking at School: Implications for School Smoking Policy
Authors: Soteriades Elpidoforos S. , DiFranza Joseph R. , Savageau Judith A. , Nicolaou Michael
Published: October 2009

ABSTRACT: Students who violate school smoking policies present a difficult health and disciplinary issue for school officials. Professionals know little about the characteristics of students who smoke at school. In a prospective study of 679 students in two cities in central Massachusetts, researchers examined how nicotine dependence contributes to the problem of smoking at school. After three years of follow up, smoking at school was reported by 10.3% of students. Among subjects who admitted to smoking at school, 63% reported that symptoms of nicotine dependence preceded their smoking at school. After adjusting for other variables, student smokers with symptoms of nicotine dependence were nine times more likely to report smoking in school (OR 9.1, 95% CI 2.9 – 28.5) than were student smokers without symptoms. Smoking at school was more common among daily smokers and those who paid for their own cigarettes. Age, gender, race, and parental smoking status were not significantly associated with students' reports of smoking at school. These data suggest nicotine dependence as an important contributor to the problem of smoking at school, but not the only reason why students violate school smoking policies. Disciplinary action against students caught violating school smoking policies should he supplemented with an offer of treatment for nicotine dependence.
Injuries to Preschool Children and Infection Control Practices in Childcare Programs
Authors: Waibel Ruth , Misra Ranjita
Published: October 2009

ABSTRACT: Injuries represent the leading cause of death for children aged 0 to 12 years, and exposure to blood or bodily fluids at the time of injury may pose a health and safety problem. More than 800,000 injuries were reported in 2000, and many occurred in childcare programs. This survey examined rate, type, and extent of injuries in centers and the infection control practices employed by staff. Participants included 131 children aged six weeks to seven years, enrolled in two childcare programs in an urban setting. Eight hundred ninety‐seven injury reports with 1,023 (126 simultaneous) injuries were recorded over a one‐year period. Results indicated the majority of injuries (39%) were for bites and 11% were self‐inflicted. Injuries were classified as minor (99%) or moderate (1%) with 73% receiving first aid by staff. Bleeding from injuries was minimal in 14% of injuries, while no injuries reported moderate or severe bleeding. The rate of medically attended (first aid treatment) injury was 5.31 per 100,000 child hours. Injury rates decreased with age in the center (P = .001), were higher for males (P = .036), and occurred most frequently in the morning (P = .001). Age, gender, and time of the day were significant predictors of injuries in the multivariate model.
Physical Activity Behaviors and Perceived Life Satisfaction Among Public High School Adolescents
Authors: Valois Robert F. , Zullig Keith J. , Huebner E. Scott , Drane J. Wanzer
Published: October 2009

ABSTRACT: This study explored relationships between perceived life satisfaction and physical activity behaviors in a statewide sample of adolescents in South Carolina (n = 4,758) using the CDC Youth Risk Behavior Survey (YRBS) and the Brief Multidimensional Student Life Satisfaction Scale (BMSLSS). Adjusted logistic regression analyses and multivariate models constructed separately revealed significant race by gender results. Not exercising for 20 minutes over the past 7 days (sweating and hard breathing), not performing stretching exercising (past 7 days), not exercising to strengthen or tone muscles (past 7 days), spending < 20 minutes actually exercising or playing sports in PE class, not playing on sport teams run by school, and not playing on sport teams run by outside school organizations were associated (p = .05) with reduced life satisfaction for specific race/gender groups. Results suggest implications for school and community‐based physical activity programs. Future research should consider measures of life satisfaction as a component of comprehensive assessments of adolescent physical activity behaviors infieldwork, research, and program evaluation.
Options for Sustaining School‐Based Health Centers
Authors: Swider Susan M. , Valukas Amy
Published: October 2009

ABSTRACT: Several methods exist for financing and sustaining operations of school‐based health centers (SBHCs). Promising sources of funds include private grants, federal grants, and slate funding. Recently, federal regulation changes mandated that federal funding specifically for SBHCs go only to SBHCs affiliated with a Federally Qualified Health Center (FQHC). Becoming a FQHC allows a SBHC to bill Medicaid at a higher rate, be notified about federal grants, and access the federal drug‐pricing program. However, FQHCs must bill for services, including a sliding‐fee scale based on ability to pay; develop a governance board with a majority of consumer members; provide a set of designated primary care services; and serve all people regardless of ability to pay. Private grants impose fewer restrictions and usually provide start‐up and demonstration funds for specific program needs. Such funds are generally time limited, so new programs need to be incorporated into the operational budget of the center. State funding proves relatively stable, but fiscal challenges in some states made these funds less available. Using a variety of funding sources will enable ongoing provision of health care to students. Overall, SBHCs should consider infrastructure development that allows a variety of funding options, including formalizing existing partnership commitments, engaging in a needs assessment and strategic planning process, developing the infrastructure for FQHC status, and implementing a billing system for client services.
HIV/AIDS Knowledge, Attitudes, Related Behaviors, and Sources of Information Among Korean Adolescents
Authors: Yoo Hyera , Lee Sun Hae , Kwon Bo Eun , Chung Sulki , Kim Sanghee
Published: October 2009

ABSTRACT: To examine HIV/AIDS knowledge, attitudes, related behaviors, and sources of HIV/AIDS information among high school‐aged students in South Korea. One thousand and seventy‐seven students (586 females and 491 males) from 5 high schools from 5 representative school districts participated in the survey. A self‐administered questionnaire measuring knowledge (19 true‐false items), attitudes (4 items, 5‐point Likert‐type scale), sources of information (6 items, yes/no), and sexual behaviors (8 items, yes/no) was utilized. The level of HIV/AIDS knowledge among Korean adolescents was moderate, with the mean scores of 13.93 out of 19 for males and 13.35 for females (p < .01). Attitudes toward persons with HIV/AIDS were negative, with the mean scores of 3.06 for males and 3.09 for females. Of 42 respondents (4.4%) who had engaged in sexual intercourse, 18 (40%) had used condoms. Almost half of the total respondents reported they were not concerned about HIV/AIDS (46.0%), and 94.4% indicated the need for receiving HIV prevention education in the future. The respondents identified TV (52.5%) and school classes (32.1%) as the two major sources of information on HIV/AIDS. Only a few pointed to their parents (1.3%) as a source of information. This preliminary study summarizes the current status of prevention education on HIV/AIDS available in Korea and can provide implications for developing more differentiated intervention strategies specific to culture, age, and gender.
School Tobacco Policies in a Tobacco‐Growing State
Authors: Hahn Ellen J. , Rayens Mary Kay , Rasnake Rob , York Nancy , Okoli Chizimuzo T.C. , Riker Carol A.
Published: October 2009

ABSTRACT: This study examined factors associated with tobacco‐free policies and tobacco cessation in schools serving children in grades 6 to 12 in a tobacco‐growing state using a cross‐sectional telephone survey of school administrators from public and private middle and high schools (N = 691), representing 117 of the 120 Kentucky counties. Trained health department staff contacted 1028 schools; 691 (67%) participated in a phone survey, which lasted an average of 19 minutes. Variables of interest were indoor and outdoor smoking policies, fund‐raising in Bingo halls, provision of cessation and prevention programs, owning or leasing a tobacco base, if the school received money from tobacco companies, type of school (public vs private), and school setting (urban vs rural). Only 20% of Kentucky schools reported comprehensive tobacco‐free policies. Urban area schools were nearly twice as likely to have a tobacco‐free campus than rural schools. Schools that did fund‐raising in smoky Bingo halls were 30% less likely to have tobacco‐free school policies. While few schools had a tobacco affiliation, those that received money from tobacco companies or grew tobacco were nearly 3 times as likely to provide cessation resources, compared to schools without tobacco affiliation. Rural schools were less likely to be tobacco free and provide cessation services. School‐related, off‐campus, extracurricular events might be considered as an element of tobacco‐free school policy. Schools with tobacco affiliation may provide more cessation resources due to the increased prevalence of tobacco use in these areas.
Addition of an aerated iron‐rich waste‐activated sludge to control the soluble sulphide concentration in sewage
Authors: Zhang Lehua , De Gusseme Bart , Cai Lankun , De Schryver Peter , Marzorati Massimo , Boon Nico , Lens Piet , Verstraete Willy
Published: October 2009

Hydrogen sulphide emission in sewers is associated with toxicity, corrosion and odour and also yields considerable costs. The purpose of this study was to evaluate whether the soluble sulphide concentration in raw sewage can be controlled by dosing an iron‐rich waste‐activated sludge (WAS) or an iron‐rich aerated waste‐activated sludge (AWAS). An average soluble sulphide elimination of 99% was achieved at an iron‐rich AWAS to sewage ratio (v/v) of 16%, whereas dosage of iron‐poor AWAS at the same ratio decreased the soluble sulphide in the raw sewage by only 53%. Our lab‐scale tests suggest that dosing iron‐rich AWAS to sewage did not affect the chemical oxygen demand (COD) and total ammonia nitrogen (TAN) removal as well as the nitrification efficiency in the receiving activated sludge system. The results indicate that iron‐rich AWAS dosage is a feasible technique to remediate the sulphide problem in sewers.
The use of restaurant inspection disclosure systems as a means of communicating food safety information
Authors: Filion Katie , Powell Douglas A.
Published: October 2009

The World Health Organization estimates that up to 30% of individuals in developed countries become ill from food or water each year. Up to 70% of these illnesses are estimated to be linked to food prepared at foodservice establishments. Consumer confidence in the safety of food prepared in restaurants is fragile, varying significantly from year to year, with many consumers attributing foodborne illness to foodservice. One of the key drivers of restaurant choice is consumer perception of the hygiene of a restaurant. Restaurant hygiene information is something consumers desire, and when available, may use to make dining decisions.
Clean restrooms: how important are they to restaurant consumers?
Authors: Barber Nelson , Scarcelli Joseph M.
Published: October 2009

There are many choices to make in restaurant dining, and for experienced consumers, the expectation of safe, quality food has increased. The foodservice industry is in a challenging and competitive environment. Determining what factors of customer satisfaction are important to maintain or increase market share is critical to success. For consumers, there are few opportunities to evaluate food handling, safety and cleanliness practices of a restaurant. Research has shown that consumers are concerned with restroom cleanliness, with a functioning restroom having a positive influence on customers' perception of the restaurant; and has also been shown to impact the choice of where to eat or whether to return to a restaurant. This study tested these assumptions by using a data set from the southwestern US, finding that consumers are concerned with restaurant cleanliness and food safety, with restrooms an important factor to consumers when assessing the cleanliness of an eating establishment.
A Generalized Method for Estimating Multiaxial Elastic-Plastic Notch Stresses and Strains, Part 1: Theory
Authors: Hoffmann M. , Seeger T.
Published: October 2009

The well known approximation formulas valid for uniaxial notch stresses are extended to multiaxial stress states in order to establish a load - equivalent notch stress and strain relationship. The correlation between equivalent and principal notch stresses and strains is obtained by applying theory of plasticity in combination with an assumption concerning one stress or strain component. The approximation method is summarized in a solution scheme. Finally aspects of accuracy are discussed.
On an Improved Time Integration Scheme for Stiff Constitutive Models of Inelastic Deformation
Authors: Banthia Vinod , Mukherjee Subrata
Published: October 2009

For the time-integration of stiff constitutive models of inelastic deformation, the explicit (one step Euler) integration scheme can be used provided the time step size is closely monitored and controlled. The time step size control scheme based on prescribed error bounds is of limited use because it requires an a priori estimate of the maximum nonelastic strain rate for the selection of a proper error bound. In this paper, a new scheme for time-step size control is presented. This scheme automatically scales the time-step size by the maximum nonelastic strain rate. That the new scheme is superior to the old one is evident from the results of the various problems presented here.
Simultaneous measures of electropalatography and intraoral pressure in selected voiceless lingual consonants and consonant sequences of German
Authors: Fuchs Susanne , Koenig Laura L.
Published: October 2009

This work assessed relationships among intraoral pressure (IOP), electropalatographic (EPG) measures, and consonant sequence duration, in the following obstruents, clusters, and affricates of German: /t/, /ʃ/, /ʃt/, and /ʧ͜/. The data showed significant correlations between IOP and percentage of articulatory contact (PC) for all speakers, whereas duration and place of articulation (measured by the EPG center of gravity) contributed less to IOP changes. Speakers differed in the strength of this relationship, possibly reflecting differences in vocal tract morphology or degree of laryngeal abduction. Single-point EPG and IOP measures in fricatives showed consistent correspondences across consonantal contexts, but the relationships for the stops were more complex and reflected positional effects. Temporal compression was observed for both members of the cluster, but only the fricative portion of the affricate. Conversely, coarticulation was observed for both the stop and fricative portion of the affricate, but only for the stop portion of the cluster, possibly reflecting biomechanical constraints. No clear differences were observed in coarticulatory resistance for stops and fricatives. These data contribute to a limited literature on articulatory-aerodynamic relationships in voiceless consonants and consonant sequences, and will provide a baseline for considering longer combinations of obstruents.
Why do Chinese alligators (Alligator sinensis) form bellowing choruses: A playback approach
Authors: Wang Xianyan , Wang Ding , Zhang Song , Wang Chaolin , Wang Renping , Wu Xiaobing
Published: October 2009

Crocodilians are quite vocal relative to other reptile groups, and the alligators are among the most vocal of the crocodilians. The Chinese alligator, Alligator sinensis, is usually solitary but engages in bellowing choruses in certain waters during the mating season. This paper reports the organization of Chinese alligator’s bellowing choruses based upon field observations and playback experiments. Alligators of both genders engaged in the choruses, remaining immobile throughout and inclining toward bellowing synchronously (i.e., starting and finishing at about the same time). The choruses lasted about 10 min with abrupt onset and offset. Moreover, playback experiments revealed that both male and female alligators responded equally to bellowing stimuli from the same and opposite sexes and that none of the tested alligators approached the loudspeaker in spite of playback of male or female stimuli. These suggest that Chinese alligators may not bellow to compete for or attract mates during the choruses. Instead, when their ecological behaviors, namely, dispersed inhabitation, multi-copulation, restricted mating season, etc., are considered, we hypothesize that they may synchronize bellows to enhance group detectability for assembling individuals into certain waters for subsequent copulations.
Numerical investigation of nonlinear propagation distortion effects in helicopter rotor noise
Authors: Menounou Penelope , Vitsas Panagiotis A.
Published: October 2009

The effect of nonlinear propagation distortion on helicopter rotor noise is presented based on measured data for low-speed descent and numerical calculations that predict the noise level away from the helicopter with and without nonlinear effects. It is shown that for some frequency bands the difference between linear and nonlinear calculations can be as high as 7 dB. Blade vortex interaction (BVI) noise, the dominant noise contributor during descent, is mainly examined. It is shown that advancing side BVI noise is affected by nonlinear distortion, while retreating side BVI noise is not. Based on signal characteristics at source, two quantities are derived. The first quantity (termed polarity) is based on the pressure gradient of the source signal and can be used to determine whether a BVI signal will evolve as an advancing or a retreating side signal. The second quantity (termed weighted rise time) is a measure of the impulsiveness of the BVI signal and can be used to determine at which frequency nonlinear effects start to appear. Finally, polarity and weighted rise time are shown to be applicable in cases of BVI noise generated from different blade tips, as well as in cases of non-BVI noise.
Wave scattering from encapsulated microbubbles subject to high-frequency ultrasound: Contribution of higher-order scattering modes
Authors: Chen Jiusheng , Hunter Kendall S. , Shandas Robin
Published: October 2009

The theoretical understanding of encapsulated microbubble response to high-frequency ultrasound (HFUS) excitation is still limited although some novel experimental HFUS contrast imaging techniques have been well developed. In this paper, the higher-order modal (HOM) contributions to the scattered field are studied for such microbubbles driven by 1–100 MHz ultrasound. An exact solution of all small-amplitude vibrational modes of a single encapsulated microbubble in water is given by the wave scattering theory (WST) method and compared to results obtained from Church’s Rayleigh–Plesset-like model for the small-amplitude radial oscillation of a microbubble in an incompressible fluid. From numerical results, we show that the HOM field contribution is significant for scattering properties from individual Nycomed microbubbles with normalized frequency ≥0.2. It is also shown that the multiple scattering is strengthened for monodispersed Definity® microbubbles of 3 μm radius at frequencies >40 MHz. However, comparisons between the authors' analyses and known experimental data for polydispersed Definity® microbubbles indicate that the HOM contributions are insignificant in attenuation estimation at frequencies <50 MHz. In conclusion, the WST model analysis suggests that HOM scattering is an important consideration for single bubbles but may be less critical in the modeling of polydispersed Definity® bubbles at high frequencies.
Simulation of shear wave propagation in a soft medium using a pseudospectral time domain method
Authors: Bastard Cécile , Remeniéras Jean-Pierre , Callé Samuel , Sandrin Laurent
Published: October 2009

Elastography applications require the use of efficient models to simulate the propagation of shear waves in soft media such as human tissues. These models are needed to improve understanding of the measured displacement field, to reconstruct the viscoelasticity of heterogeneous tissues, and to test inversion algorithms. This paper reports a numerical model based on a pseudospectral time domain method developed to simulate shear and compression wave propagation in an axisymmetric heterogeneous viscoelastic medium. This model was adapted to the study of soft tissues where the ratio between the compression and the shear wave velocity was about a thousand and validated in the homogeneous situation by comparison with an analytical model based on elastodynamic Green’s functions. Displacements obtained experimentally using transient elastography are presented, compared with simulation results, and discussed.
Utilizing reciprocal maximum length sequences within a multichannel context to generate a natural, spatial sounding reverberation.
Authors: Trivedi Uday S. , Xiang Ning
Published: October 2009

The development of artificial reverberation has made considerable progress in recent years. Simultaneous advances in knowledge and computational power have allowed for a rapid development and application in the design of virtual room environments. Within such situations, simulating room acoustics is critical for producing a convincing immersive experience. This research explores the application of a multi-channel loudspeaker setup that can be employed in simulating such an environment. An algorithm to shape and vary the spaciousness within the context of an artificially generated reverberation is implemented. The pseudo-random properties of reciprocal maximum-length sequences (R-MLSs) allow for a deterministic decorrelation between all channels. The use of R-MLS also provides several advantages over using traditional random noise. This paper will discuss the potential applications in creating virtual spaces and variable acoustic environments using multiple channel systems.
Binaural reproduction of spherical microphone array signals.
Authors: Atkins Joshua D.
Published: October 2009

An efficient method for the production of binaural audio signals from spherical microphone array signals using head related impulse responses (HRIRs) is presented. The processing is done directly in the spherical Fourier transform domain which offers significant speed advantages over the conventional method of beamforming toward each HRIR measurement point. The encoding of HRIRs into the spherical Fourier domain is complicated by the fact that the available HRIR databases (CIPIC, MIT, KEMAR) use irregular sampling positions around the sphere and do not contain data for sound coming from angles below the subject. However, for spatially bandlimited processing it is possible to use an LMS technique with regularization to perform the spherical Fourier transform of these HRIRs. A real-time system with head-tracking using the eigenmike (TM) and the CIPIC HRIR database is presented which processes spherical harmonics up to third order. Since the head-rotation operation is performed digitally, this technique is especially useful for remote surveillance and virtual reality systems with complex acoustic scenes.
Sound transmission through a fluctuating ocean (1979) and ocean acoustic tomography (1995): An intertwined history.
Authors: Worcester Peter F. , Munk Walter H.
Published: October 2009

Early attempts at understanding scintillations in sound transmission through the ocean assumed that ocean fine structure is homogeneous and isotropic. It is, in fact, dominated by internal waves, which are neither homogeneous nor isotropic. Sound Transmission Through a Fluctuating Ocean (Flatté et al., Cambridge University Press, Cambridge, England 1979) combined recently developed internal-wave models with path-integral methods to predict the fluctuations of resolved acoustic multipaths. At that time, Ocean Acoustic Tomography (Munk et al., Cambridge University Press, Cambridge, England 1995), which uses ray travel times to determine large-scale ocean structure, had just been proposed. The wideband acoustic sources and receivers required to make travel-time measurements for tomography also provided the technology needed to quantify acoustic fluctuations. Conversely, internal-wave-induced scattering limits travel-time measurement precision. Tomography experiments at 25-km range provided some of the earliest tests of path-integral predictions. Subsequent tomography experiments provided data at ever-increasing ranges and decreasing frequencies. The Acoustic Thermometry of Ocean Climate project made measurements at megameter ranges with 1400-m vertical line array receivers. The next step is a modular distributed VLA capable of spanning the full water column that is under development to enable separation of acoustic modes using spatial filtering and to fully characterize deep-water acoustic time fronts.
Characterization of deep acoustic shadow zone arrivals.
Authors: Van Uffelen Lora J. , Worcester Peter F.
Published: October 2009

Acoustic shadow-zone arrivals first observed in the late 1990s on horizontal receiving arrays in the North Pacific Ocean revealed significant acoustic energy penetrating the geometric shadow by an estimated 500–1000 m. An extensive vertical line array deployed in conjunction with 250-Hz acoustic sources at ranges of 500- and 1000-km during SPICEX, a long-range propagation experiment conducted from June to November 2004 in the North Pacific, confirmed the presence of these anomalously deep arrivals and enabled an examination of their vertical structure. Parabolic equation simulations incorporating scattering consistent with the Garrett–Munk internal-wave spectrum at full strength are able to describe both the energy contained in and vertical extent of deep shadow-zone arrivals. Several hundred acoustic receptions were recorded during the experimental deployment, enabling a statistical characterization of the energy and vertical extent of these arrivals as well as an investigation of the evolution of the arrivals throughout the nearly 6 months of acoustic receptions.
Internal wave strength inversion based on the shape of the axial finale.
Authors: Heaney Kevin D.
Published: October 2009

Flatte had a significant impact on my dissertation and early education in the field of ocean acoustic propagation. In particular, Flatte’s work on the impact of internal wave scattering on deep ocean propagation was central to my early work in adiabatic mode scattering in the presence of deep water internal waves. In this paper, we will revisit some of Flatte’s wave propagation in a random media theory and show its phenomenological impact on deep water propagation, primarily within his explanation of the Slice89 experiment. In this experiment the axial finale (latest arriving energy) is broadened in depth. Flatte correctly asserted that this was due to internal wave scattering to higher modes (with larger depth extents) and used this as a method for heuristically determining the internal wave strength. Results from Heaney [Ph.D. thesis, SIO-UCSD (1997)] will be presented using the ATOC experiment. More recent results using NPAL data as well as more recent modeling will be presented. The impact of these results on deep water anti-submarine warfare and the extension of these results to basin scale propagation (>10000-km ranges) will be made.
Convergence of Born series using Padé approximants.
Authors: Tsui Jing M. , Denis Max , Thompson Charles
Published: October 2009

The solution of acoustic wave scattering can be calculated in terms of Born series in the low contrast limit. Recasting the Born series in terms of Padé approximants allows one to extend its validity at higher contrast. However, as the value of the contrast is further increased, the direct calculation of the scattering field using the Padé approximant coefficients may exhibit local divergence in the scattering volume. Origin of this problem and its possible solution will be discussed. The results will be presented.
Generation of cavitation in mercury by means of an electromagnetic acoustic source.
Authors: Wang Qi , Manzi Nicholas J. , Holt Glynn R. , Roy Ronald A. , Cleveland Robin O.
Published: October 2009

An electromagnetic acoustic source (EMAS) consists of a flat electrical coil, a thin insulating membrane, and a metal plate. The EMAS is excited by discharging a capacitor through the coil, and the resulting eddy currents produce a repulsive force on the metal plate launching acoustic waves. Here an EMAS was used to excite acoustic waves in a cylindrical chamber of mercury (75-mm ID and 75-mm long) with the metal plate bonded to the bottom of the tank. The lid of the chamber had a re-entrant cylinder such that a steel plate was positioned 50 mm from the EMAS face. A laser Doppler vibrometer was used to monitor the deflection of the plate to ascertain the acoustic field. A 75-mm-diameter coil was wound with either 18, 27, or 36 turns. The EMAS plate was steel, aluminum, or just a Mylar insulating membrane with no metallic plate. Experiments were carried out for capacitances of 0.5, 2, and 4 μF, charging voltage of 0–10 kV, number of coils, and properties of the plate. For a 4-μF capacitor charged to 10 kV, cavitation was produced in the mercury with duration of 150 μs.[Supported by the ORNL Spallation Neutron Source US-DOE Contract DE-AC05-00OR22725]
Boundary element simulation of fully three-dimensional bubble dynamics.
Authors: Kurtz Jason P. , Hamilton Mark F.
Published: October 2009

A three-dimensional boundary element method is presented for simulating bubble dynamics in incompressible, inviscid fluids (such that the fluid velocity is the gradient of a potential). The method is applied to simulate the migration and collapse of bubbles near rigid boundaries. The motivation is to model multiple cavitation bubble interactions near the hard surfaces of kidney stones that occur in shock-wave lithotripsy. In order to accurately compute the fluid velocity, the method employs a novel curvilinear representation of the bubble geometry that enforces the global continuity of the unit normal vector. Contrary to the axisymmetric setting, the global continuity of the derivative of the parametrization, known as C1 continuity, cannot be enforced. Enforcing the continuity of the unit normal, known as G1 continuity, guarantees that the surface gradient of the velocity potential is orthogonal to the normal vector and enables a more accurate computation of the total gradient. The presentation concludes with several movies showing the simulated bubble migration and collapse, which are in good agreement with other known simulations (that assume axisymmetry) and experimentally obtained photographs. Results for multiple-bubble scenarios in non-axisymmetric configurations will also be presented. [Work supported by the ARL:UT Postdoctoral Fellow Program and NIH DK070618.]
Acoustic streaming caused by the oscillation of an irregular surface.
Authors: Aho Katherine , Vejar Elaine , Thompson Charles
Published: October 2009

The analysis of acoustic streaming generated by oscillatory flow over a two-dimensional flexible boundary will be presented. The time-averaged slip velocity that results from the gradient of the Reynolds stress is obtained. Of particular interest is the coupling between transverse motion of boundary and longitudinal oscillation of the fluid.
Low-back vowel merger in Minnesotan English.
Authors: Arctander Kaitlyn , Kinney Hannah , Esposito Christina M.
Published: October 2009

Current linguistic observation suggests that the low-back vowels (specifically, international phonetic alphabet [ɑ] and [ɔ]) are merging in the majority of American English dialects. There has yet to be a phonetic study of this merger which would provide empirical support for this observation in the mid-western varieties of English. The current study investigates this merger experimentally. Speakers of Minnesotan English were asked to read a list of 100 monosyllabic words containing the low-back vowels (filler words were also produced). The first (F1) and second (F2) formants were measured automatically for each vowel. Observations of speakers suggest three possible outcomes: (1) both vowels merge to [ɑ], (2) both merge to [ɔ], or (3) that the merger results in a novel vowel which is slightly higher than [ɑ] but lower than [ɔ].
The role of gender and ethnicity in the specification of American English vowels.
Authors: Trent-Brown Sonja A. , Woodworth Kyle P. , Dreyer Joline C.
Published: October 2009

This study explores acoustic variation in vowel phoneme production for adult speakers of General American English. Peterson and Barney (1952) conducted an analysis of the acoustic features of American English vowels in order to map the phonological vowel space; Hillenbrand et al. (1995) replicated and extended their classic study. Both studies presented acoustic measures for men and women. The findings across the two studies include target values for various acoustic cues in the speaker productions, including fundamental frequency (F0), formant frequencies, and duration measures. However, no mention is made of speaker ethnic background, and studies have since suggested that there is evidence of both perceptual and acoustic variations with respect to speaker ethnicity [Thomas & Reaser, (2004)]. The purpose of the current research is to replicate and extend the findings of the previous studies to determine whether differences exist with respect to ethnicity that do not arise from dialect features. Speakers were recorded producing words and sentences containing /hVd/ target stimuli. Speaker productions were screened for dialectal features. Temporal and spectral steady-state vowel measures of acoustic variation (F0, formant values, and vowel duration) were obtained for all speakers. Results are presented for the variations across the speaker gender/ethnic groups. [Hope College Psychology Department, The Carl Frost Center for Social Science Research, The Jacob E. Nyenhuis Student/Faculty Cooperative Grant