bluuebunny/crossref_metadata_2025 huggingface dataset:
Language revolution behind the cultural curtain
Authors: PROSHINA ZOYA G.
Published: February 2014

This paper focuses on the innovative, revolutionary features of the World Englishes paradigm that shook the education world in the late 20th century. I speak about key concepts that are salient to the paradigm, such as pluricentricity, diversity, functionality, and equality as articulated by Kachru, such as inclusivity and variability, as well as the controversies emerging in and related to education, for example, the struggle between prescriptive and descriptive approaches, and norms and usage. With reference to Expanding Circle contexts such as China and Russia, I emphasize the cultural underpinnings that create the greatest challenge for intervarietal communicators, as measured in terms of Smith's (; 1992) notion of interpretability. Such challenges help explain the significant role assigned to intercultural communication studies in tertiary education curricula in these countries. Revealing cultural identity when speaking in English as a communicative mediating tool is not an easy task for individuals and requires a special training. No easier is the listening and negotiating of other cultural meanings, all of which sets new perspectives for researchers and educators, while also encouraging cooperation between them.
English on Korean television
Authors: LEE JAMIE SHINHEE
Published: February 2014

This study discusses verbal humor in entertainment media and examines polarizing representations of English on Korean television. English is a source of stress as well as a medium of humor. Language anxiety about English speaking skills is frequently focalized and viewed as a personal challenge by Korean celebrities, but they often transform their linguistic ‘complex’ into humorous talk. This study argues that using English, possibly the most revered and yet the most feared language in Korea, in humor is sociolinguistically significant, embodying attitudinal, emotional, and experiential ambivalence about English in globalization‐minded contemporary Korea. The findings of the study suggest that generation‐conscious ageism regarding English proficiency typically characterizes senior citizens as sociolinguistically underperforming, which sometimes forces them to be in a vulnerable position both in familial and social contexts. Increasing use of English on Korean television divides bilingual viewers and monolingual viewers and whether one can be entertained and humored by television programs may become another English‐related stratification variable in Korea.
Linguistic chutzpah and the Speak Good Singlish movement
Authors: WEE LIONEL
Published: February 2014

This paper discusses the Speak Good Singlish Movement, which was started as a response to the Speak Good English Movement, the latter having been initiated by the Singapore government. The Speak Good Singlish Movement represents a good example of linguistic chutzpah, where speakers demonstrate confidence in their language choices while also having the metalinguistic awareness and sophistication needed to articulate rationales for these choices. The paper argues that linguistic chutzpah is especially important in relation to the global spread of English, where speakers are often confronted with the need to make decisions about language while not being able to rely on traditional sources of authority (such as the speech community or prescriptive grammars). Under such circumstances, speakers need to be able to adopt confident stances about their language choices, even while knowing that these choices may be met with criticism. To make this point, the paper also describes two cases involving anxieties about appropriate language use.
New reflections on the evolutionary dynamics of world Englishes
Authors: SCHNEIDER EDGAR W.
Published: February 2014

The ongoing expansion and diversification of English, especially in the Expanding Circle, calls for a comparative analysis of these processes and a deepened theoretical understanding of this dynamism. A key question asked in this paper is whether or to what extent the ‘Dynamic Model’ of the evolution of Postcolonial Englishes is able to explain these processes and can be applied to Extending Circle countries as well. A decade after its first influential publication, reactions to the model are surveyed systematically, including some new applications, modifications, approaches at testing it, and some criticism. Applying the comparative‐descriptive framework of this model and some of its constituent components, the progress of English is outlined in China, Korea, and (less broadly) Japan, the ASEAN, Thailand, Namibia, and Rwanda. Furthermore, it is argued that a similar dynamism is driving the widespread emergence of hybrid mixes between local languages and English and phenomena of ‘poststructuralist diffusion,’ English being adopted by whatever means, in fragments and unconstrained of norm concerns, driven by strongly utilitarian considerations. A tabular summary assessment compares these processes with constituents of the Dynamic Model and finds that despite some similarities it is not well suited to grasp the vibrant developments of the Expanding Circle. Instead, the notion of ‘transnational attraction’ is defined and proposed as an appropriate conceptual framework.
Singapore English and styling the Ah Beng
Authors: BROWN DAVID WEST , JIE TEO SHI
Published: February 2014

This paper explores stylized renderings of Singapore English as such ‘verbal art’ is used by Singaporean youth in popular online forums. In order to analyze these stylizations, this study uses corpora collected from two forums frequented by Singaporean students. The data suggests that posters often use stylized representations to perform or to ventriloquize the identity of an Ah Beng (a kind of hustler or gangster). Implicated in such performances are sometimes complex negotiations of class, gender, and ethnicity. The relationship among the linguistic features central to our study and the social meanings signaled by those features suggest the value of approaches that emphasize the range of pragmatic and metapragmatic meanings or indexicalities that accrue to features in modeling variation in Singapore English.
Diachronic stability in Indian English lexis
Authors: LAMBERT JAMES
Published: February 2014

In the late 1930s two British commentators, A.F. Kindersley and R.C. Goffin, published articles on various linguistic features (semantic, grammatical, orthographical, and phonological) of the English language as used in India. These two glossaries offer a valuable insight into late‐Raj Indian English. In order to assess the extent of change over the intervening 70‐plus years, a comparison of the content of those glossaries to present‐day Indian English has been made. The overall picture is one of surprising stability, especially given the strong resistance by educationalists and others who have long stigmatised local variations as ‘errors’. This stability over time suggests a long‐standing endonormativity that has hitherto not been recognised. Many of the features discussed have even longer stable histories, suggesting an even lengthier endonormativity. This type of diachronic investigation may have similar implications for many other varieties of English.
English in the Kingdom of Saudi Arabia
Authors: MAHBOOB AHMAR , ELYAS TARIQ
Published: February 2014

This paper examines the history, politics and discourses around the (teaching of) English language in the Kingdom of Saudi Arabia (KSA). In addition to discussing the issues and debates around English language, this paper also looks at whether and how English has been localised to suit the local needs and practices. Based on an analysis of English language textbooks used in KSA, the paper shows that Saudi English mostly follows and ascribes to the grammatical norms of standard Englishes. The paper does identify some deviations in the grammar of English in these textbooks; however, these are within the range of features of varieties of Englishes found in other Inner, Outer and Expanding circle varieties of Englishes. The paper then identifies a number of discursive and multimodal features of Saudi English that are much more locally oriented and reflect local cultural norms and practices. The findings of this paper suggest that English in Saudi Arabia is in the process of being nativised and that this Saudi English reflects recognisably local cultural, religious and social values and beliefs.
Acute effect of dietary fatty acid composition on postprandial metabolism in women
Authors: Clevenger Hui C. , Kozimor Amanda L. , Paton Chad M. , Cooper Jamie A.
Published: February 2014

New Findings

What is the central question of this study?

We wanted to determine the effect of three high‐fat meals enriched with different fatty acids [monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs) or saturated fatty acids (SFAs)] on diet‐induced thermogenesis and substrate oxidation in premenopausal women of normal weight.

What is the main finding and its importance?

We found that a PUFA‐rich high‐fat meal led to a greater diet‐induced thermogenesis in normal‐weight premenopausal women compared with SFA‐ or MUFA‐rich high‐fat meals. The greater diet‐induced thermogenesis for PUFA‐rich meals could contribute to differences in long‐term overall energy balance, and thus, weight maintenance. Substrate utilization was not different between treatments.

The composition of fatty acids in a diet may differentially affect metabolism, thus playing a role in the development of obesity. Our aim was to study the effects of three high‐fat (HF) meals with different degrees of saturation on diet‐induced thermogenesis (DIT) and substrate oxidation in premenopausal women of normal weight. Fifteen healthy, normal‐weight women, aged 18–35 years, participated in a randomized cross‐over study, in which they consumed isocaloric HF meals (70% of energy from fat) rich in saturated fat (SFA; 40% of total energy), monounsaturated fat (MUFA; 42% of total energy) or polyunsaturated fat (PUFA; 42% of total energy). Indirect calorimetry was used to measure respiratory gases for a 5 h postprandial period. The data collected were used to determine respiratory exchange ratio for assessing substrate oxidation, as well as energy expenditure for the determination of DIT. The area under the curve for DIT following the PUFA‐rich HF meal was greater than that of the SFA‐ or MUFA‐rich HF meals [10.0 ± 0.7, 8.6 ± 0.8 and 8.9 ± 1.2 kcal (5 h)−1 (P = 0.02) for PUFA, MUFA and SFA, respectively]. No significant difference was found in respiratory exchange ratio (0.86 ± 0.01, 0.85 ± 0.01 and 0.85 ± 0.01 for PUFA‐, MUFA‐ and SFA‐rich HF meals, respectively) or substrate utilization following the three different HF meals (12.2 ± 1.0, 11.2 ± 0.5 and 11.6 ± 0.9 g for cumulative postprandial carbohydrate oxidation following the PUFA‐, MUFA‐ and SFA‐rich HF meals, respectively; and 3.8 ± 0.4, 4.1 ± 0.2 and 4.1 ± 0.3 g for cumulative fat oxidation of the PUFA‐, MUFA‐ and SFA‐rich HF meals, respectively). In conclusion, acute ingestion of a PUFA‐rich HF meal induced a greater DIT in normal‐weight women compared with SFA‐ or MUFA‐rich HF meals. No significant differences were found for substrate utilization.
Intermittent and continuous high‐intensity exercise training induce similar acute but different chronic muscle adaptations
Authors: Cochran Andrew J. R. , Percival Michael E. , Tricarico Steven , Little Jonathan P. , Cermak Naomi , Gillen Jenna B. , Tarnopolsky Mark A. , Gibala Martin J.
Published: February 2014

New Findings

What is the central question of this study?

How important is the interval in high‐intensity interval training (HIIT)?

What is the main finding and its importance?

The intermittent nature of HIIT is important for maximizing skeletal muscle adaptations to this type of exercise, at least when a relatively small total volume of work is performed in an ‘all‐out’ manner. The protein signalling responses to an acute bout of HIIT were generally not predictive of training‐induced outcomes. Nonetheless, a single session of exercise lasting <10 min including warm‐up, performed three times per week for 6 weeks, was sufficient to improve maximal aerobic capacity.

High‐intensity interval training (HIIT) performed in an ‘all‐out’ manner (e.g. repeated Wingate tests) is a time‐efficient strategy to induce skeletal muscle remodelling towards a more oxidative phenotype. A fundamental question that remains unclear, however, is whether the intermittent or ‘pulsed’ nature of the stimulus is critical to the adaptive response. In study 1, we examined whether the activation of signalling cascades linked to mitochondrial biogenesis was dependent on the manner in which an acute high‐intensity exercise stimulus was applied. Subjects performed either four 30 s Wingate tests interspersed with 4 min of rest (INT) or a bout of continuous exercise (CONT) that was matched for total work (67 ± 7 kJ) and which required ∼4 min to complete as fast as possible. Both protocols elicited similar increases in markers of adenosine monophosphate‐activated protein kinase (AMPK) and p38 mitogen‐activated protein kinase activation, as well as Peroxisome proliferator‐activated receptor gamma coactivator 1‐alpha (PGC‐1α) mRNA expression (main effects for time, P ≤ 0.05). In study 2, we determined whether 6 weeks of the CONT protocol (3 days per week) would increase skeletal muscle mitochondrial content to a similar extent to what we have previously reported after 6 weeks of INT. Despite similar acute signalling responses to the CONT and INT protocols, training with CONT did not increase the maximal activity or protein content of a range of mitochondrial markers. However, peak oxygen uptake was higher after CONT training (from 45.7 ± 5.4 to 48.3 ± 6.5 ml kg−1 min−1; P < 0.05) and 250 kJ time trial performance was improved (from 26:32 ± 4:48 to 23:55 ± 4:16 min:s; P < 0.001) in our recreationally active participants. We conclude that the intermittent nature of the stimulus is important for maximizing skeletal muscle adaptations to low‐volume, all‐out HIIT. Despite the lack of skeletal muscle mitochondrial adaptations, our data show that a training programme based on a brief bout of high‐intensity exercise, which lasted <10 min per session including warm‐up, and performed three times per week for 6 weeks, improved peak oxygen uptake in young healthy subjects.
Introducing a rat model of prenatal androgen‐induced polycystic ovary syndrome in adulthood
Authors: Tehrani Fahimeh Ramezani , Noroozzadeh Mahsa , Zahediasl Saleh , Piryaei Abbas , Azizi Fereidoun
Published: February 2014

New Findings

What is the central question of this study?

Would it be possible to produce a rat model of polycystic ovary syndrome (PCOS), in which the fetuses are exposed to testosterone for a short time and exhibit both endocrine and ovarian disturbances similar to PCOS, while maintaining normal reproductive system morphology in adulthood?

What is the main finding and its importance?

Prenatal exposure to a single dose of testosterone during the critical period of fetal development facilitates the production of a functional rat model of PCOS with minimal morphological disorders in adulthood. Production of a functional rat model that resembles many features of PCOS may contribute to a better understanding of this syndrome.

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women, with a prevalence of 8–12% during the reproductive years. In the present study, using prenatal exposure to a single dose of testosterone during the critical period of fetal development, we aimed to introduce an enhanced rat model that would exhibit both endocrine and ovarian disturbances similar to PCOS, while maintaining normal reproductive system morphology in adulthood. Ten pregnant rats were injected s.c. with 5 mg free testosterone on gestational day 20, while control rats received only solvent. The development and function of the reproductive system in female offspring were examined in adulthood. Prenatally androgenized offspring had irregular oestrous cycles compared with control animals, and their anogenital and anovaginal distances were increased compared with control rats (P < 0.001). No significant differences were observed in the lengths of the vagina and clitoris or the number of nipples between the two groups. Levels of testosterone and luteinizing hormone and the luteinizing hormone/follicle‐stimulating hormone ratio were increased in prenatally androgenized offspring compared with control animals (P < 0.05). The numbers of preantral and antral follicles in the ovaries of prenatally androgenized offspring were also increased compared with control rats (P = 0.07 and P < 0.01, respectively). The number of corpora lutea was decreased in prenatally androgenized offspring compared with control rats. Cystic follicles were observed in the ovaries of prenatally androgenized offspring. Prenatal exposure to a single dose of testosterone during the critical period of fetal development could facilitate the development a functional rat model of PCOS in adulthood, with minimal morphological disorders in the reproductive system.
Chalenges and Opportunities in Mathematical and Theoretical Biology and Medicine: Foreword to Volume 2 (2013) of Biomath
Authors: Castillo-Chavez Carlos
Published: February 2014

The challenges faced today at the interface of the computational, life, social, mathematical and data sciences expand as the world's population approaches the seven billion mark. Today, we are asked to address questions over multiple temporal and spatial scales as well as across various levels of organization. In the process, the world has placed mathematical scientists, broadly defined to include computational, computer, statistics and data science experts, at the heart of trans-disciplinary and interdisciplinary efforts aimed primarily at assessing arguably the most important technical challenge of our times, namely, how to model and quantify uncertainty. Twenty first century research is driven to a great extent by questions involving the study of the dynamics of biological process. And so, we have been forced to account for the impact of social systems, bringing the role of human-decisions to the forefront of most efforts to put the power of the quantitative sciences into the hands of policy and decision makers.The challenges faced by mathematical scientist include ...
Shear Layer Driven Acoustic Modes in a Cylindrical Cavity
Authors: Stephens David B. , Verdugo Francisco R. , Bennett Gareth J.
Published: February 2014

This paper describes the interior acoustic pressure of a cylindrical cavity driven by a shear layer. Existing cavity flow literature is generally focused on rectangular cavities, where the resonance is either longitudinal or the result of excited depth modes inside the cavity. The design of the present circular cavity is such that azimuthal duct modes can be excited in various combinations with depth modes depending on free stream velocity. An acoustic simulation of the system was used to identify the modes as a function of frequency when the system is driven by an acoustic point source. With appropriate manipulation of the free stream flow, abrupt mode switching and mode oscillation were both observed, and a condition with a dominant azimuthal mode was found. The strength of the lock-on was documented for the various resonance conditions, and the effects of the cavity opening size and location were studied.
Vibrational spectra of CO adsorbed on oxide thin films: A tool to probe the surface defects and phase changes of oxide thin films
Authors: Savara Aditya
Published: February 2014

Thin films of iron oxide were grown on Pt(111) single crystals using cycles of physical vapor deposition of iron followed by oxidative annealing in an ultrahigh vacuum apparatus. Two procedures were utilized for film growth of ∼15–30 ML thick films, where both procedures involved sequential deposition+oxidation cycles. In procedure 1, the iron oxide film was fully grown via sequential deposition+oxidation cycles, and then the fully grown film was exposed to a CO flux equivalent to 8 × 10−7 millibars, and a vibrational spectrum of adsorbed CO was obtained using infrared reflection-absorption spectroscopy. The vibrational spectra of adsorbed CO from multiple preparations using procedure 1 show changes in the film termination structure and/or chemical nature of the surface defects—some of which are correlated with another phase that forms (“phase B”), even before enough of phase B has formed to be easily detected using low energy electron diffraction (LEED). During procedure 2, CO vibrational spectra were obtained between deposition+oxidation cycles, and these spectra show that the film termination structure and/or chemical nature of the surface defects changed as a function of sequential deposition+oxidation cycles. The authors conclude that measurement of vibrational spectra of adsorbed CO on oxide thin films provides a sensitive tool to probe chemical changes of defects on the surface and can thus complement LEED techniques by probing changes not visible by LEED. Increased use of vibrational spectra of adsorbed CO on thin films would enable better comparisons between films grown with different procedures and by different groups.
Effect of thermal annealing on the properties of transparent conductive In–Ga–Zn oxide thin films
Authors: Li Ling , Fan Lina , Li Yanhuai , Song Zhongxiao , Ma Fei , Liu Chunliang
Published: February 2014

Amorphous In–Ga–Zn oxide (IGZO) thin films were prepared using radio frequency magnetron sputtering at room temperature. Upon thermal annealing at temperatures even up to 500 °C, the amorphous characteristics were still maintained, but the electronic properties could be considerably enhanced. This could be ascribed to the increased optical band gap and the increased oxygen vacancies, as corroborated by the microstructure characterizations. In addition, the surface became smoother upon thermal annealing, guaranteeing good interface contact between electrode and a-IGZO. The optical transmittance at 400–800 nm exceeded 90% for all samples. All in all, thermal annealing at appropriate temperatures is expected to improve the performances of relevant a-IGZO thin film transistors.
Self‐assessed performance improves statistical fusion of image labels
Authors: Bryan Frederick W. , Xu Zhoubing , Asman Andrew J. , Allen Wade M. , Reich Daniel S. , Landman Bennett A.
Published: February 2014

Purpose:

Expert manual labeling is the gold standard for image segmentation, but this process is difficult, time‐consuming, and prone to inter‐individual differences. While fully automated methods have successfully targeted many anatomies, automated methods have not yet been developed for numerous essential structures (e.g., the internal structure of the spinal cord as seen on magnetic resonance imaging). Collaborative labeling is a new paradigm that offers a robust alternative that may realize both the throughput of automation and the guidance of experts. Yet, distributing manual labeling expertise across individuals and sites introduces potential human factors concerns (e.g., training, software usability) and statistical considerations (e.g., fusion of information, assessment of confidence, bias) that must be further explored. During the labeling process, it is simple to ask raters to self‐assess the confidence of their labels, but this is rarely done and has not been previously quantitatively studied. Herein, the authors explore the utility of self‐assessment in relation to automated assessment of rater performance in the context of statistical fusion.

Methods:

The authors conducted a study of 66 volumes manually labeled by 75 minimally trained human raters recruited from the university undergraduate population. Raters were given 15 min of training during which they were shown examples of correct segmentation, and the online segmentation tool was demonstrated. The volumes were labeled 2D slice‐wise, and the slices were unordered. A self‐assessed quality metric was produced by raters for each slice by marking a confidence bar superimposed on the slice. Volumes produced by both voting and statistical fusion algorithms were compared against a set of expert segmentations of the same volumes.

Results:

Labels for 8825 distinct slices were obtained. Simple majority voting resulted in statistically poorer performance than voting weighted by self‐assessed performance. Statistical fusion resulted in statistically indistinguishable performance from self‐assessed weighted voting. The authors developed a new theoretical basis for using self‐assessed performance in the framework of statistical fusion and demonstrated that the combined sources of information (both statistical assessment and self‐assessment) yielded statistically significant improvement over the methods considered separately.

Conclusions:

The authors present the first systematic characterization of self‐assessed performance in manual labeling. The authors demonstrate that self‐assessment and statistical fusion yield similar, but complementary, benefits for label fusion. Finally, the authors present a new theoretical basis for combining self‐assessments with statistical label fusion.
Toward an organ based dose prescription method for the improved accuracy of murine dose in orthovoltage x‐ray irradiators
Authors: Belley Matthew D. , Wang Chu , Nguyen Giao , Gunasingha Rathnayaka , Chao Nelson J. , Chen Benny J. , Dewhirst Mark W. , Yoshizumi Terry T.
Published: February 2014

Purpose:

Accurate dosimetry is essential when irradiating mice to ensure that functional and molecular endpoints are well understood for the radiation dose delivered. Conventional methods of prescribing dose in mice involve the use of a single dose rate measurement and assume a uniform average dose throughout all organs of the entire mouse. Here, the authors report the individual average organ dose values for the irradiation of a 12, 23, and 33 g mouse on a 320 kVp x‐ray irradiator and calculate the resulting error from using conventional dose prescription methods.

Methods:

Organ doses were simulated in the Geant4 application for tomographic emission toolkit using the MOBY mouse whole‐body phantom. Dosimetry was performed for three beams utilizing filters A (1.65 mm Al), B (2.0 mm Al), and C (0.1 mm Cu + 2.5 mm Al), respectively. In addition, simulated x‐ray spectra were validated with physical half‐value layer measurements.

Results:

Average doses in soft‐tissue organs were found to vary by as much as 23%–32% depending on the filter. Compared to filters A and B, filter C provided the hardest beam and had the lowest variation in soft‐tissue average organ doses across all mouse sizes, with a difference of 23% for the median mouse size of 23 g.

Conclusions:

This work suggests a new dose prescription method in small animal dosimetry: it presents a departure from the conventional approach of assigninga single dose value for irradiation of mice to a more comprehensive approach of characterizing individual organ doses to minimize the error and uncertainty. In human radiation therapy, clinical treatment planning establishes the target dose as well as the dose distribution, however, this has generally not been done in small animal research. These results suggest that organ dose errors will be minimized by calibrating the dose rates for all filters, and using different dose rates for different organs.
Improved proton computed tomography by dual modality image reconstruction
Authors: Hansen David C. , Petersen Jørgen Breede Baltzer , Bassler Niels , Sørensen Thomas Sangild
Published: February 2014

Purpose:

Proton computed tomography (CT) is a promising image modality for improving the stopping power estimates and dose calculations for particle therapy. However, the finite range of about 33 cm of water of most commercial proton therapy systems limits the sites that can be scanned from a full 360° rotation. In this paper the authors propose a method to overcome the problem using a dual modality reconstruction (DMR) combining the proton data with a cone‐beam x‐ray prior.

Methods:

A Catphan 600 phantom was scanned using a cone beam x‐ray CT scanner. A digital replica of the phantom was created in the Monte Carlo code Geant4 and a 360° proton CT scan was simulated, storing the entrance and exit position and momentum vector of every proton. Proton CT images were reconstructed using a varying number of angles from the scan. The proton CT images were reconstructed using a constrained nonlinear conjugate gradient algorithm, minimizing total variation and the x‐ray CT prior while remaining consistent with the proton projection data. The proton histories were reconstructed along curved cubic‐spline paths.

Results:

The spatial resolution of the cone beam CT prior was retained for the fully sampled case and the 90° interval case, with the MTF = 0.5 (modulation transfer function) ranging from 5.22 to 5.65 linepairs/cm. In the 45° interval case, the MTF = 0.5 dropped to 3.91 linepairs/cm For the fully sampled DMR, the maximal root mean square (RMS) error was 0.006 in units of relative stopping power. For the limited angle cases the maximal RMS error was 0.18, an almost five‐fold improvement over the cone beam CT estimate.

Conclusions:

Dual modality reconstruction yields the high spatial resolution of cone beam x‐ray CT while maintaining the improved stopping power estimation of proton CT. In the case of limited angles, the use of prior image proton CT greatly improves the resolution and stopping power estimate, but does not fully achieve the quality of a 360° proton CT scan.
Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound
Authors: Gruber Matthew J. , Bader Kenneth B. , Holland Christy K.
Published: February 2014

Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (<1 MHz) and low amplitudes (<0.5 MPa). The objective of this study was to determine cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity®) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540–900 kHz) and a broad frequency bandwidth (0.54–1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 ± 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle.
Dynamic adjustment of echolocation pulse structure of big-footed myotis (Myotis macrodactylus) in response to different habitats
Authors: Wang Lei , Luo Jinhong , Wang Hongna , Ou Wei , Jiang Tinglei , Liu Ying , Lyle Dennis , Feng Jiang
Published: February 2014

Studying relationships between characteristics of sonar pulses and habitat clutter level is important for the understanding of signal design in bat echolocation. However, most studies have focused on overall spectral and temporal parameters of such vocalizations, with focus less on potential variation in frequency modulation rates (MRs) occurring within each pulse. In the current study, frequency modulation (FM) characteristics were examined in echolocation pulses recorded from big-footed myotis (Myotis macrodactylus) bats as these animals searched for prey in five habitats differing in relative clutter level. Pulses were analyzed using ten parameters, including four structure-related characters which were derived by dividing each pulse into three elements based on two knees in the FM sweep. Results showed that overall frequency, pulse duration, and MR all varied across habitat. The strongest effects were found for MR in the body of the pulse, implying that this particular component plays a major role as M. macrodactylus, and potentially other bat species, adjust to varying clutter levels in their foraging habitats.
Mosquito (Aedes aegypti) flight tones: Frequency, harmonicity, spherical spreading, and phase relationships
Authors: Arthur Benjamin J. , Emr Kevin S. , Wyttenbach Robert A. , Hoy Ronald R.
Published: February 2014

Mosquito flight produces a tone as a side effect of wing movement; this tone is also a communication signal that is frequency-modulated during courtship. Recordings of tones produced by tethered flying male and female Aedes aegypti were undertaken using pairs of pressure-gradient microphones above and below, ahead and behind, and to the left and right over a range of distances. Fundamental frequencies were close to those previously reported, although amplitudes were lower. The male fundamental frequency was higher than that of the female and males modulated it over a wider range. Analysis of harmonics shows that the first six partials were nearly always within 1 Hz of integer multiples of the fundamental, even when the fundamental was being modulated. Along the front-back axis, amplitude attenuated as a function of distance raised to the power 2.3. Front and back recordings were out of phase, as were above and below, while left and right were in phase. Recordings from ahead and behind showed quadratic phase coupling, while others did not. Finally, two methods are presented for separating simultaneous flight tones in a single recording and enhancing their frequency resolution. Implications for mosquito behavior are discussed.
Analog model for thermoviscous propagation in a cylindrical tube
Authors: Thompson Stephen C. , Gabrielson Thomas B. , Warren Daniel M.
Published: February 2014

Modeling acoustic propagation in tubes including the effects of thermoviscous losses at the tube walls is important in applications such as thermoacoustics, hearing aids, and wind musical instruments. Frequency dependent impedances for a tube transmission line model in terms of the so-called thermal and viscous functions are well established, and form the basis for frequency domain analysis of systems that include tubes. However, frequency domain models cannot be used for systems in which significant nonlinearities are important, as is the case with the pressure-flow relationship through the reed in a woodwind instrument. This paper describes a cylindrical tube model based on a continued fraction expansion of the thermal and viscous functions. The model can be represented as an analog circuit model which allows its use in time domain system modeling. This model avoids problems with fractional derivatives in the time domain.
A model that predicts the binaural advantage to speech intelligibility from the mixed target and interferer signals
Authors: Cosentino Stefano , Marquardt Torsten , McAlpine David , Culling John F. , Falk Tiago H.
Published: February 2014

A model is presented that predicts the binaural advantage to speech intelligibility by analyzing the right and left recordings at the two ears containing mixed target and interferer signals. This auditory-inspired model implements an equalization-cancellation stage to predict the binaural unmasking (BU) component, in conjunction with a modulation-frequency estimation block to estimate the “better ear” effect (BE) component of the binaural advantage. The model's performance was compared to experimental data obtained under anechoic and reverberant conditions using a single speech-shaped noise interferer paradigm. The internal BU and BE components were compared to those of the speech intelligibility model recently proposed by Lavandier et al. [J. Acoust. Soc. Am. 131, 218–231 (2012)], which requires separate inputs for target and interferer. The data indicate that the proposed model provides comparably good predictions from a mixed-signals input under both anechoic and reverberant conditions.
Simulation studies of a recorder in three dimensions
Authors: Giordano N.
Published: February 2014

The aeroacoustics of a recorder are explored using a direct numerical simulation based on the Navier–Stokes equations in three dimensions. The qualitative behavior is studied using spatial maps of the air pressure and velocity to give a detailed picture of jet dynamics and vortex shedding near the labium. In certain cases, subtle but perhaps important differences in the motion of the air jet near the edge of the channel as compared to the channel center are observed. These differences may be important when analyzing experimental visualizations of jet motion. The quantitative behavior is studied through analysis of the spectrum of the sound pressure outside the instrument. The effect of chamfers and of changes in the position of the labium relative to the channel on the tonal properties are explored and found to be especially important in the attack portion of the tone. Changes in the spectrum as a result of variations in the blowing speed are also investigated as well as the behavior of the spectrum when the dominant spectral component switches from the fundamental to the second harmonic mode of the resonator tube.
Variation in low-frequency estimates of sound levels based on different units of analysis
Authors: Hawkins Russell S. , Miksis-Olds Jennifer L. , Smith Chad M.
Published: February 2014

The measurement and analysis of underwater sound is a complicated process because of the variable durations of contributing sources and constantly changing water column dynamics. Because the ambient sound distribution does not always follow a Gaussian structure and may be nonstationary in time, analysis over an extended period is required to accurately characterize the data. Utilizing recordings from the Indian Ocean, the temporal variation in ambient sound including transient signals was examined using multiple processing window lengths and subsampling intervals. Results illustrate the degree of uncertainty in sound levels based on different units of analysis. The average difference between sound level estimates in the 10–30 Hz band due to subsampling was 2 dB and as high as 4 dB. The difference in the full band (5–110 Hz) was as high as 6 dB. Longer averaging windows (200 vs 60 s) resulted in larger variations over different subsampling intervals. This work demonstrates how sampling protocols within a single dataset can influence results and acknowledges that comparative studies at the same location but with different sampling protocols can be substantial if signal processing parameters are not statistically accounted for to confirm interpretation of results and observed trends.
Acoustic mode coupling induced by nonlinear internal waves: Evaluation of the mode coupling matrices and applications
Authors: Yang T. C.
Published: February 2014

This paper applies the mode coupling equation to calculate the mode-coupling matrix for nonlinear internal waves appearing as a train of solitons. The calculation is applied to an individual soliton up to second order expansion in sound speed perturbation in the Dyson series. The expansion is valid so long as the fractional sound speed change due to a single soliton, integrated over range and depth, times the wavenumber is smaller than unity. Scattering between the solitons are included by coupling the mode coupling matrices between the solitons. Acoustic fields calculated using this mode-coupling matrix formulation are compared with that obtained using a parabolic equation (PE) code. The results agree very well in terms of the depth integrated acoustic energy at the receivers for moving solitary internal waves. The advantages of using the proposed approach are: (1) The effects of mode coupling can be studied as a function of range and time as the solitons travel along the propagation path, and (2) it allows speedy calculations of sound propagation through a packet or packets of solitons saving orders of magnitude computations compared with the PE code. The mode coupling theory is applied to at-sea data to illustrate the underlying physics.
Binaural interference: Effects of temporal interferer fringe and interstimulus interval
Authors: Camalier Corrie R. , Wesley Grantham D. , Bernstein Leslie R.
Published: February 2014

Binaural interference refers to the phenomenon in which the potency of binaural cues conveyed by a “target” stimulus occupying one spectral region is degraded by the presence of an “interferer” stimulus occupying a spectral region remote from the target. It is typified by conditions in which thresholds for detection of interaural temporal difference conveyed by a high-frequency target are elevated when the target is accompanied by a spectrally remote low-frequency interferer. This study explored effects of temporal relations between targets and interferers on binaural interference. In the first experiment, duration by which the interferer preceded and/or trailed the target (onset and offset “fringes”) was varied. Results indicated binaural interference decreased with total duration of the temporal fringe, but did not depend on whether that duration was composed of onset, offset, or onset + offset fringes. In the second experiment, binaural interference was measured as a function of the interstimulus interval (ISI) between the two presentations of the target. Results indicated that shorter ISIs increased thresholds in both the interferer and no-interferer conditions, but did not affect binaural interference. These results suggest that the mechanisms underlying the effects of manipulations of the interferer temporal fringe and manipulation of the ISI are essentially independent.
The role of syntax in maintaining the integrity of streams of speech
Authors: Kidd Gerald , Mason Christine R. , Best Virginia
Published: February 2014

This study examined the ability of listeners to utilize syntactic structure to extract a target stream of speech from among competing sounds. Target talkers were identified by voice or location, which was held constant throughout a test utterance, and paired with correct or incorrect (random word order) target sentence syntax. Both voice and location provided reliable cues for identifying target speech even when other features varied unpredictably. The target sentences were masked either by predominantly energetic maskers (noise bursts) or by predominantly informational maskers (similar speech in random word order). When the maskers were noise bursts, target sentence syntax had relatively minor effects on identification performance. However, when the maskers were other talkers, correct target sentence syntax resulted in significantly better speech identification performance than incorrect syntax. Furthermore, conformance to correct syntax alone was sufficient to accurately identify the target speech. The results were interpreted as supporting the idea that the predictability of the elements comprising streams of speech, as manifested by syntactic structure, is an important factor in binding words together into coherent streams. Furthermore, these findings suggest that predictability is particularly important for maintaining the coherence of an auditory stream over time under conditions high in informational masking.
A computational model for the dynamic stabilization of Rayleigh-Bénard convection in a cubic cavity
Authors: Carbo Randy M. , Smith Robert W. M. , Poese Matthew E.
Published: February 2014

The dynamic stability of Rayleigh-Bénard convection with vertical vibration in a cubic container is computationally modeled. Two parametric drives are considered (sinusoidal and rectangular), as well as two thermal boundary conditions on the sidewalls (insulating and conducting). The linearized equations are solved using a spectral Galerkin method and Floquet analysis. Both the synchronous and the subharmonic regions of instability are recovered. The conditions necessary for dynamic stability are reported for a range of Rayleigh numbers from critical to 107 and for Prandtl numbers in the range of 0.1–7. The linear model is compared to the data set available in the literature where the performance of an inverted pulse tube cryocooler is measured.
Acoustic and vibration response of a structure with added noise control treatment under various excitations
Authors: Rhazi Dilal , Atalla Noureddine
Published: February 2014

The evaluation of the acoustic performance of noise control treatments is of great importance in many engineering applications, e.g., aircraft, automotive, and building acoustics applications. Numerical methods such as finite- and boundary elements allow for the study of complex structures with added noise control treatment. However, these methods are computationally expensive when used for complex structures. At an early stage of the acoustic trim design process, many industries look for simple and easy to use tools that provide sufficient physical insight that can help to formulate design criteria. The paper presents a simple and tractable approach for the acoustic design of noise control treatments. It presents and compares two transfer matrix-based methods to investigate the vibroacoustic behavior of noise control treatments. The first is based on a modal approach, while the second is based on wave-number space decomposition. In addition to the classical rain-on-the-roof and diffuse acoustic field excitations, the paper also addresses turbulent boundary layer and point source (monopole) excitations. Various examples are presented and compared to a finite element calculation to validate the methodology and to confirm its relevance along with its limitations.
Evidence for independent time-unit processing of speech using noise promoting or suppressing masking release
Authors: Healy Eric W. , Youngdahl Carla L. , Apoux Frédéric
Published: February 2014

The relative independence of time-unit processing during speech reception was examined. It was found that temporally interpolated noise, even at very high levels, had little effect on sentence recognition using masking-release conditions similar to those of Kwon et al. [(2012). J. Acoust. Soc. Am. 131, 3111−3119]. The current data confirm the earlier conclusions of Kwon et al. involving masking release based on the relative timing of speech and noise. These data also indicate substantial levels of independence in the time domain, which has implications for current theories of speech perception in noise.
Binaural detection with narrowband and wideband reproducible noise maskers. IV. Models using interaural time, level, and envelope differences
Authors: Mao Junwen , Carney Laurel H.
Published: February 2014

The addition of out-of-phase tones to in-phase noises results in dynamic interaural level difference (ILD) and interaural time difference (ITD) cues for the dichotic tone-in-noise detection task. Several models have been used to predict listeners' detection performance based on ILD, ITD, or different combinations of the two cues. The models can be tested using detection performance from an ensemble of reproducible-noise maskers. Previous models cannot predict listeners' detection performance for reproducible-noise maskers without fitting the data. Here, two models were tested for narrowband and wideband reproducible-noise experiments. One model was a linear combination of ILD and ITD that included the generally ignored correlation between the two cues. The other model was based on a newly proposed cue, the slope of the interaural envelope difference (SIED). Predictions from both models explained a significant portion of listeners' performance for detection of a 500-Hz tone in wideband noise. Predictions based on the SIED approached the predictable variance in the wideband condition. The SIED represented a nonlinear combination of ILD and ITD, with the latter cue dominating. Listeners did not use a common strategy (cue) to detect tones in the narrowband condition and may use different single frequencies or different combinations of frequency channels.