bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel MRI tests of orocecal transit time and whole gut transit time: studies in normal subjects
Authors: Chaddock G. , Lam C. , Hoad C. L. , Costigan C. , Cox E. F. , Placidi E. , Thexton I. , Wright J. , Blackshaw P. E. , Perkins A. C. , Marciani L. , Gowland P. A. , Spiller R. C.
Published: October 2013

Background

Colonic transit tests are used to manage patients with Functional Gastrointestinal Disorders. Some tests used expose patients to ionizing radiation. The aim of this study was to compare novel magnetic resonance imaging (MRI) tests for measuring orocecal transit time (OCTT) and whole gut transit time (WGT), which also provide data on colonic volumes.

Methods

21 healthy volunteers participated. Study 1: OCTT was determined from the arrival of the head of a meal into the cecum using MRI and the Lactose Ureide breath test (LUBT), performed concurrently. Study 2: WGT was assessed using novel MRI marker capsules and radio‐opaque markers (ROMs), taken on the same morning. Studies were repeated 1 week later.

Key Results

OCTT measured using MRI and LUBT was 225 min (IQR 180–270) and 225 min (IQR 165–278), respectively, correlation rs = 0.28 (ns). WGT measured using MRI marker capsules and ROMs was 28 h (IQR 4–50) and 31 h ± 3 (SEM), respectively, correlation rs = 0.85 (p < 0.0001). Repeatability assessed using the intraclass correlation coefficient (ICC) was 0.45 (p = 0.017) and 0.35 (p = 0.058) for MRI and LUBT OCTT tests. Better repeatability was observed for the WGT tests, ICC being 0.61 for the MRI marker capsules (p = 0.001) and 0.69 for the ROM method (p < 0.001) respectively.

Conclusions & Inferences

The MRI WGT method is simple, convenient, does not use X‐ray and compares well with the widely used ROM method. Both OCTT measurements showed modest reproducibility and the MRI method showed modest inter‐observer agreement.
Impairment of the proximal to distal tonic gradient in the human diabetic stomach
Authors: Min Y. W. , Hong Y. S. , Ko E.‐J. , Lee J. Y. , Min B.‐H. , Sohn T. S. , Kim J. J. , Rhee P.‐L.
Published: October 2013

Background

Little has been known about the contractile characteristics of diabetic stomach. We investigated spontaneous contractions and responses to acetylcholine in the gastric muscle in diabetic patients and non‐diabetic control subjects according to the region of stomach.

Methods

Gastric specimens were obtained from 26 diabetics and 55 controls who underwent gastrectomy at Samsung Medical Center between February 2008 and November 2011. Isometric force measurements were performed using circular muscle strips from the different regions of stomach under basal condition and in response to acetylcholine.

Key Results

Basal tone of control was higher in the proximal stomach than in the distal (0.63 g vs 0.46 g, p = 0.027). However, in diabetics, basal tone was not significantly different between the proximal and distal stomach (0.75 g vs 0.62 g, p = 0.32). The distal stomach of diabetics had higher basal tone and lower frequency than that of control (0.62 g vs 0.46 g, p = 0.049 and 4.0/min vs 4.9/min, p = 0.049, respectively). After exposure to acetylcholine, dose‐dependent increases of basal tone, peak, and area under the curve (AUC) were noticed in both proximal and distal stomach of the two groups. In the proximal stomach, however, the dose‐dependent increase of basal tone and AUC was less prominent in diabetics than in control.

Conclusions & Inferences

On the contrary to control, the proximal to distal tonic gradient was not observed in diabetic stomach. Diabetic stomach also had lower frequency of spontaneous contraction in the distal stomach and less acetylcholine‐induced positive inotropic effect in the proximal stomach than control.
Kaempferol 3‐O‐rhamnoside‐7‐O‐rhamnoside is an endogenous flavonol inhibitor of polar auxin transport in Arabidopsis shoots
Authors: Yin Ruohe , Han Kerstin , Heller Werner , Albert Andreas , Dobrev Petre I. , Zažímalová Eva , Schäffner Anton R.
Published: October 2013

Polar auxin transport (PAT) plays key roles in the regulation of plant growth and development. Flavonoids have been implicated in the inhibition of PAT. However, the active flavonoid derivative(s) involved in this process in vivo has not yet been identified. Here, we provide evidence that a specific flavonol bis‐glycoside is correlated with shorter plant stature and reduced PAT.

Specific flavonoid‐biosynthetic or flavonoid‐glycosylating steps were genetically blocked in Arabidopsis thaliana. The differential flavonol patterns established were analyzed by high‐performance liquid chromatography (HPLC) and related to altered plant stature. PAT was monitored in stem segments using a radioactive [3H]‐indole‐3‐acetic acid tracer.

The flavonoid 3‐O‐glucosyltransferase mutant ugt78d2 exhibited a dwarf stature in addition to its altered flavonol glycoside pattern. This was accompanied by reduced PAT in ugt78d2 shoots. The ugt78d2‐dependent growth defects were flavonoid dependent, as they were rescued by genetic blocking of flavonoid biosynthesis. Phenotypic and metabolic analyses of a series of mutants defective at various steps of flavonoid formation narrowed down the potentially active moiety to kaempferol 3‐O‐rhamnoside‐7‐O‐rhamnoside. Moreover, the level of this compound was negatively correlated with basipetal auxin transport.

These results indicate that kaempferol 3‐O‐rhamnoside‐7‐O‐rhamnoside acts as an endogenous PAT inhibitor in Arabidopsis shoots.
Body mass index and leukocyte telomere length in adults: a systematic review and meta‐analysis
Authors: Müezzinler A. , Zaineddin A. K. , Brenner H.
Published: October 2013

The objective of this study was to provide a systematic review and meta‐analysis of studies on the relationship between body mass index (BMI) and leukocyte telomere length (LTL). Relevant studies were identified by a systematic search of MEDLINE, Embase and Web of Knowledge databases. Pooled correlation and regression coefficients were calculated using meta‐analysis methods for both cross‐sectional and longitudinal studies. Studies without suitable data for meta‐analysis were summarized separately. Overall, 29 studies were included, of which 16 were eligible for meta‐analysis, including two longitudinal studies. The majority of studies reported an inverse relationship between BMI and telomere length. For cross‐sectional studies, the pooled estimates for correlation and regression coefficients were −0.057 (95% confidence interval [CI]: −0.102 to −0.012) and −0.008 kBP kg m−2 (95% CI: −0.016 to 0.000), respectively. The two longitudinal studies were small (70 and 311 subjects), covered different age ranges and yielded inconsistent results. No evidence of any gender difference was observed. Despite some variation between studies and very limited data from longitudinal studies, the results of this meta‐analysis suggest a biologically plausible inverse association between BMI and LTL in adults. However, the associations require clarification, in particular by large longitudinal studies with careful control for possible confounding factors in overall, age‐ and sex‐specific analyses.
Where to Do Things with Words
Authors: De Bruyn Ben
Published: October 2013

Inspired by Leah Price's recent plea on behalf of the study of ‘nonreading’ and literary logistics, this essay reconstructs a slice of the history of reading locations by analysing the decoration advice, the changing symbolic associations and the modes of print circulation connected with private libraries and toilets in the writings of two modern authors: Edith Wharton and Henry Miller.
‘But every man cannot be a surgeon’
Authors: Milota Megan
Published: October 2013

Although Elizabeth Gaskell's treatment of public health concerns, education, industrialization and workers' rights have all received ample attention in literary criticism, her various depictions of male medical practitioners, their patients and the complicated social and gender practices that affected their practice has yet to be thoroughly studied. Building upon the work of Michel Foucault and Thomas Laqueur, this article will show that while certain stereotypes of the doctor–patient relationship exist in Gaskell's fiction, her work also exposes a broader range of power structures, ones where women exerted various degrees of influence. Gaskell's fiction also reflects the significant roles that the British tripartite medical market and the social structure of nineteenth‐century society played in a doctor's perceived abilities and success.
Relire La poésie pure (1926) d'Henri Bremond
Authors: Baetens Jan , de Geest Dirk
Published: October 2013

Dans les discussions littéraires des années 20, au moment où triomphe le désir d'autonomie des écrivains, la notion de « poésie pure » est au cœur de tous les débats. Le concept, toutefois, n'a pas de sens bien défini. D'un côté, la « poésie pure » se distingue par son exploitation de toutes les ressources du langage littéraire. Elle est alors vue comme un contrepoids salutaire au lyrisme traditionnel qui insiste trop lourdement sur le « message » du texte, au détriment de sa forme et de son style. De l'autre côté, la « poésie pure » ouvre aussi la voie d'une expérience poétique d'un type nouveau, presque religieux. Auteur d'une conférence célèbre sur le sujet (1925), Henri Bremond a proposé une réflexion fouillée de la « poésie pure ». Ses textes, pourtant, sont plus cités que lus. La présente étude tente de faire une lecture détaillée de ses principales idées et de les situer dans un contexte européen plus large.
Three patients with mood disorders showing catatonia and frontotemporal lobes atrophy
Authors: Utumi Yushi , Iseki Eizo , Arai Heii
Published: October 2013

Here we report the cases of three patients with mood disorders showing catatonia and frontotemporal lobe atrophy. Catatonia is a syndrome linked to frontal dysfunction that most frequently occurs in patients with mood disorders. The diagnostic criteria of catatonia and frontotemporal dementia partly overlap. In the present patients, catatonia might be closely related to frontal dysfunction caused by frontotemporal lobe atrophy. With regard to therapeutics for catatonia, we found that administering a low dose of lorazepam alone or after electroconvulsive therapy may be useful for treating and preventing catatonia. We also found that administering glutaminate antagonists such as memantine may be useful for treating lorazepam‐resistant catatonia.
Are Real GDP Levels Stationary in African Countries?
Authors: Ying Zheng , Dong Chang‐Rui , Chang Hsu‐Ling , Su Chi‐Wei
Published: October 2013

In this study, we apply flexible Fourier stationary unit root test proposed by Enders and Lee (2012) to assess the non‐stationary properties of the per capita real gross domestic product (GDP) for 32 African countries. We find that Fourier stationary unit root test has higher power than linear method if the true data‐generating process of per capita real GDP is in fact a stationary nonlinear process of an unknown form with structural change using the low frequency components. We investigate the stationarity of per capita real GDP from the nonlinear point of view and provide robust evidence that clearly indicates that real output is well characterised by a nonlinear, mean‐reverting process, namely Benin, Botswana, Burundi, Cameroon, Senegal, Sierra Leone and South Africa. Our evidence points that these seven countries are nonlinear stationary, implying that per capita real GDP follows a steady rate of growth, and policy innovations then have temporary effects. These results have important policy implications for African countries.
Patient‐centred care in type 2 diabetes – an altered professional role for diabetes specialist nurses
Authors: Boström Eva , Isaksson Ulf , Lundman Berit , Lehuluante Abraraw , Hörnsten Åsa
Published: October 2013

Little research has been done to try to understand how patient‐centred care is understood and practised by healthcare professionals specialising in patients with diabetes. Experiences from patient‐centred practices need to be highlighted as a way of motivating diabetes specialist nurses to take a patient‐centred approach. The aim of this study was to describe diabetes specialist nurses' experiences of practising patient‐centred care in the context of a type 2 diabetes intervention. The study design was descriptive and used qualitative methods. Focus group interviews complemented by individual semi‐structured interviews were analysed by qualitative content analysis. The main theme of the diabetes specialist nurses' experiences of practising patient‐centred care was an altered professional role. The main theme was based on two themes: ambivalence towards practising patient‐centred care and enriched relationships with the patients. The ambivalence towards practising patient‐centred care was based on the three subthemes: a position of withdrawn expertise, inconvenience of changing routines and insights that patient‐centred care is difficult but possible. Their experiences of enriched relationships with patients were based on the two subthemes: courage to discuss the severity of diabetes and increased engagement in patients' daily lives. The diabetes specialist nurses' experiences with practising patient‐centred care included doubts about their ability to practise in such a way and about the feasibility of such care. At the same time, their enriched relationships with patients were seen as an opportunity to engage in patients' lives. Training and support for practising patient‐centred care may improve diabetes specialist nurses skills in patient‐centred care and self‐management support in type 2 diabetes.
Intravenous immunoglobulin‐induced haemolysis: a case report and review of the literature
Authors: Desborough M. J. , Miller J. , Thorpe S. J. , Murphy M. F. , Misbah S. A.
Published: October 2013

Objectives

To review the incidence and clinical features of intravenous immunoglobulin (IVIg)‐induced haemolysis.

Background

Haemolysis can be a severe complication of IVIg administration. It is due to the passive transfer of blood group antibodies and may result in significant anaemia and renal failure.

Methods

We report a case of severe IVIg‐induced haemolysis; review the data reported to vigilance groups (The Medicines and Healthcare Products Regulatory Agency, European Union Drug Regulatory Authorities, Food and Drug Administration and the Canada Vigilance Centre) between January 1998 and May 2012; and systematically review IVIg‐induced haemolysis case reports (between January 1948 and January 2013).

Results

Nine hundred‐twenty five cases of IVIg‐induced haemolysis were identified from a review of cases reported to vigilance groups; 62 case reports were included in the systematic review. The majority of these were due to administration of doses of at least 2 g kg−1 of IVIg (97%). IVIg‐induced haemolysis was reported most commonly for patients with blood group A (65%) or AB (26%). One case report noted that in two patients with IVIg‐induced haemolysis both received IVIg from the same batch.

Conclusion

We make the following recommendations for the management of suspected cases of IVIg‐induced haemolysis:

Stop IVIg infusion and perform tests for haemolysis.

Check titres of anti‐blood group antibodies in IVIg.

Provide supportive management for patient with fluid and/or red blood cell transfusions if necessary.

Consider quarantine of the IVIg batch if found to be high titre for anti‐A/B.

Report reaction to regulatory/vigilance body.
Interference of an algal nutritional supplement with a urinary metabolic screening test for glycosaminoglycans in a dog suspected to have a storage disease
Authors: Sewell Adrian C. , Pankraz Alexander
Published: October 2013

The finding of excess urinary glycosaminoglycans (GAG) is the first step in the laboratory diagnosis of mucopolysaccharidosis (MPS). Urinary screening tests are based upon the binding of GAG to dimethylmethylene blue. Alternatively, paper spot tests using toluidine blue are used in human and veterinary laboratory medicine. Positive samples undergo GAG isolation for subsequent characterization. Here, we describe a 3‐year‐old English Cocker Spaniel with a positive urinary GAG test, but without other clinical signs of MPS. Urine samples were strongly positive with the dimethylmethylene blue test, and isolated GAG subjected to electrophoresis on cellulose acetate revealed a band co‐migrating with dermatan sulfate. However, the isolated GAG were resistant to digestion with chondroitinase ABC, suggesting that the band did not represent dermatan sulfate. This was confirmed by mobility of the isolated GAG different from dermatan sulfate on agarose gel electrophoresis. MPS types VI and VII were excluded by enzyme assay. To test the hypothesis of a nutritional source, a healthy control dog was fed the same dog food as the index case. His urine showed a comparable abnormal GAG screening test and electrophoretic pattern. In addition, the analysis of an algal supplement present in the administered dog food showed a similar electrophoretic GAG pattern. The Cocker Spaniel was not available for further testing after withdrawal of the supplement. Algae contain highly sulfated fucans and galactans, and it appears that commercial dog food containing such algal, and possibly other, supplements can give rise to false‐positive urinary MPS screening tests.
Convective Instability of the Darcy Flow in a Horizontal Layer With Symmetric Wall Heat Fluxes and Local Thermal Nonequilibrium
Authors: Barletta A. , Celli M. , Kuznetsov A. V.
Published: October 2013

The linear stability of the parallel Darcy throughflow in a horizontal plane porous layer with impermeable boundaries subject to a symmetric net heating or cooling is investigated. The onset conditions for the secondary thermoconvective flow are expressed through a neutral stability bound for the Darcy–Rayleigh number associated with the uniform heat flux supplied or removed from the walls. The study is performed by taking into account a condition of local thermal nonequilibrium between the solid phase and the fluid phase. The linear stability analysis is carried out according to the normal modes' decomposition of the perturbations to the basic state. The governing equations for the disturbances are solved numerically as an eigenvalue problem leading to the neutral stability condition. If compared with the asymptotic condition of local thermal equilibrium, the regime of local nonequilibrium manifests an enhanced instability. This behavior is displayed by lower critical values of the Darcy–Rayleigh number, eventually tending to zero when the thermal conductivity of the solid phase is much larger than the conductivity of the fluid phase. In this special limit, which can be invoked as an approximate model of a gas-saturated metallic foam, the basic throughflow is always unstable to external disturbances of arbitrarily small amplitude.
Completely Spectral Collocation Solution of Radiative Heat Transfer in an Anisotropic Scattering Slab With a Graded Index Medium
Authors: Ma Jing , Sun Ya-Song , Li Ben-Wen
Published: October 2013

A completely spectral collocation method (CSCM) is developed to solve radiative transfer equation in anisotropic scattering medium with graded index. Different from the Chebyshev collocation spectral method based on the discrete ordinates method (SP-DOM), the CSCM is used to discretize both the angular domain and the spatial domain of radiative transfer equation. In this approach, the angular derivative term and the integral term are approximated by the high order spectral collocation scheme instead of the low order finite difference approximations. Compared with those available data in literature, the CSCM has a good accuracy for a wide range of the extinction coefficient, the scattering albedo, the scattering phase function, the gradient of refractive index and the boundary emissivity. The CSCM can provide exponential convergence for the present problem. Meanwhile, the CSCM is much more economical than the SP-DOM. Moreover, for nonlinear anisotropic scattering and graded index medium with space-dependent albedo, the CSCM can provide smoother results and mitigate the ray effect.
Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser
Authors: Kariya H. Arthur , Peters Teresa B. , Cleary Martin , Hanks Daniel F. , Staats Wayne L. , Brisson John G. , Wang Evelyn N.
Published: October 2013

Thermal management of modern electronics is rapidly becoming a critical bottleneck of their computational performance. Air-cooled heat sinks offer ease and flexibility in installation and are currently the most widely used solution for cooling electronics. We report the characterization of a novel loop heat pipe (LHP) with a wick in the condenser, developed for the integration into an air-cooled heat sink. The evaporator and condenser are planar (102 mm × 102 mm footprint) and allow for potential integration of multiple, stacked condensers. The condenser wick is used to separate the liquid and vapor phases during condensation by capillary menisci and enables the use of multiple condensers with equal condensation behavior and performance. In this paper, the thermal–fluidic cycle is outlined, and the requirements to generate capillary pressure in the condenser are discussed. The LHP design to fulfill the requirements is then described, and the experimental characterization of a single-condenser version of the LHP is reported. The thermal performance was dependent on the fan speed and the volume of the working fluid; a thermal resistance of 0.177  °C/W was demonstrated at a heat load of 200 W, fan speed of 5000 rpm and fluid volume of 67 mL. When the LHP was filled with the working fluid to the proper volume, capillary pressure in the condenser was confirmed for all heat loads tested, with a maximum of 3.5 kPa at 200 W. When overfilled with the working fluid, the condenser was flooded with liquid, preventing the formation of capillary pressure and significantly increasing the LHP thermal resistance. This study provides the detailed thermal–fluidic considerations needed to generate capillary pressure in the condenser for controlling the condensation behavior and serves as the basis of developing multiple-condenser LHPs with low thermal resistance.
Rewarming Machine Perfusion System for Liver Transplantation
Authors: Obara Hiromichi , Matsuno Naoto , Shigeta Takanobu , Enosawa Shin , Hirano Toshihiko , Mizunuma Hiroshi
Published: October 2013

The liver is one of the most essential organs, and transplantation is an established treatment for patients with end-stage disease who have lost their liver function. However, organ shortage is a critical problem in transplantation; thus, the development of an innovative preservation system to adopt critical grafts obtained from extended criteria donors or donation after cardiac death donors as viable organs for transplantation is necessary. We recently developed a novel rewarming machine perfusion preservation system for liver transplantation, and herein discuss this system, which allows the perfusion temperature to be controlled during the transition from hypothermic to subnormothermic conditions. This system has two functions: (1) the preservation and recovery of organ function and (2) screening the organ for viability. To achieve these functions, this system has three features: (1) temperature control of the preservation perfusate and liver graft, (2) dual-controlled perfusion of the portal vein and hepatic artery, and (3) real-time monitoring of the perfusion conditions, including the flow rate, perfusion pressure and temperature. This system was useful for liver preservation and for evaluating the graft viability and recovery of functions during machine perfusion before transplantation. This novel rewarming machine preservation system was tested in an experimental model using porcine liver grafts. We report that this system has certain advantages in liver preservation, and believe that this system will positively contribute to the expansion of the organ donor pool.
Determination of absorption coefficients for audience seating from in situ measurements
Authors: Gulsrud Timothy E. , Beamer C. Walter
Published: October 2013

Audience seating constitutes the majority of fixed sound absorption in most music performance venues. An understanding of the sound absorption characteristics of audience seating is therefore essential for accurately predicting reverberation times and for evaluating different chair constructions during the design process. Room acoustics measurements were recently conducted in a small concert hall immediately before and after installation of audience seating. These measurements allow the determination of absorption coefficients for audience seating for use in the Sabine equation [L.L. Beranek and T. Hidaka, J. Acoust. Soc. of Am. 104, 3169–3177 (1998)] and in room acoustics computer modeling software. A comparison of these in situ absorption coefficients along with those determined from reverberation room measurements will be discussed.
Segmented swept sine technique for room impulse response estimation
Authors: Paulo Joel P. , Bento Coelho Jose L. , Martins Carlos M.
Published: October 2013

The swept sine technique is very popular for the measurement of room impulse response due to its large signal-to-noise ratio (SNR) and immunity against subtle time-variance and nonlinearity of the room under test. However, the acoustical measurements in the presence of high background noise levels leads usually to unsatisfactory results. For situations of high level nonstationary noise, the mean square of the overall sequence must be minimized in order to increase the SNR. The new technique named segmented swept sine consists in exciting the room with a set of M swept sine signals with application of a dedicated weighting average method and a noise pattern recognition procedure. Each swept sine signal is segmented followed by the estimation of the mean square (MS) value of the respective segment. A weighting procedure is applied to each segment according to the MS value and the likelihood between them. The average technique is then applied. This procedure ensures that the resulting swept sine signal has the highest SNR value. Several examples are presented to compare the standard swept sine and the segmented swept sine techniques, giving advantages and disadvantages of each technique.
Swept sine-based technique for minimization of annoyance using a perceptual model
Authors: Paulo Joel P. , Bento Coelho Jose L. , Martins Carlos R.
Published: October 2013

The accurate estimation of the acoustical parameters of a space to be used by people, such as theaters, concert halls, conference rooms, sport stadiums, and other public areas, implies that the measurements should be evaluated in the presence of an audience. However, for reasons of annoyance, people are usually avoided and a correction factor related to the effective absorption of the audience area is applied to the results only. This procedure does not take into account the variability of some parameters such as the relative humidity during the event, which influences considerably the magnitude frequency response. The swept sine technique is very attractive in acoustical measurements due to the high signal-to-noise ratios (SNR) and robustness against nonlinearity of the measurement chain and time variance. The use of some convenient music tracks in agreement with the perceptual masking effect minimizes the annoyance and increases the SNR simultaneously. The sinusoidal synthesis algorithm is applied to some parts of the music. After questioning a set of persons, some results based on an annoyance indicator are presented giving advantages and disadvantages of this method.
Spatial variation of acoustic energy density in lightly damped rectangular enclosures
Authors: Xu Buye , Sommerfeldt Scott D.
Published: October 2013

Since the 1990’s, acoustic energy density (ED) has been investigated for applications such as active noise control and sound equalization problems. Thus far, the developments have generally relied on the reduced spatial variation of ED. Previous studies on the spatial variation of ED in lightly damped rectangular enclosures were limited to the low frequency range where only a small number of normal modes are excited, and the relatively high frequency range where statistical methods can be applied. In this work, the properties of ED in mid-frequency range have been studied, based on a computer simulation model. Different conditions for the enclosure and the sound source have been studied. The results show good consistency with previous studies in the overlap ranges of frequency. [Work supported by NSF Grant CMS-0409319.]
Acoustic absorbers made of micro-perforated stretched ceilings and other materials
Authors: Nocke Christian , Hilge Catja , Scherrer Jean-Marc
Published: October 2013

The manufacturer of stretched ceiling systems celebrates its 40th birthday in 2007. In 2001 a nearly invisible micro-perforation was introduced to the stretched material, making it highly sound absorptive. Over the last years different setups made of micro-perforated layers, porous materials, as well as plate resonators have been investigated. As a latest addition combinations of nonwoven materials with micro-perforated layers have been experimentally investigated. In this contribution measured sound absorption coefficients of various setups with micro-perforated stretched foils and different other acoustic materials will be presented. For these assemblies no closed calculation model exists so far.
Estimation of drop size distribution from the low frequency components in the rain generated underwater acoustic noise
Authors: Thundiyil Mani , Pillai PRS
Published: October 2013

Drop size distribution (DSD) is an important parameter that completely characterizes the rain and rain generated acoustic energy. This paper presents a simple and efficient method for measuring the DSD of rain by analyzing the low-frequency components in the spectrum of rain generated acoustic noise underwater. A specially designed sensor assembly captures the acoustic noise produced due to the raindrop impacts on the water surface. Every individual drop produces acoustic noise comprising the low frequency components which has distinct characteristics in the time domain. It has been found that these distinct features vary with the size of the droplets and its velocity. Experimental evidences show that the acoustic energy of the low frequency signal is related to the size of the drops that caused the acoustic noise and, hence, the energy of the drops generated acoustic signal is a measure of the drop size. An algorithm for detecting and computing the energy of these low frequency components leading to the estimation of DSD of rain is presented in this paper. This approach has been employed in developing a Disdrometer based automatic rain gauge, which is simple, reliable, and cost effective.
Effects of scattering by air bubbles on performance of an underwater acoustic array
Authors: Culver Richard Lee , Trujillo Mario F.
Published: October 2013

Analytical and numerical calculations of the effects of nearby air bubbles on performance of an underwater acoustic array are presented. Array performance is characterized by the array gain. Two effects of air bubbles on array gain are considered: (1) attenuation of the direct path signal of interest and (2) additive, correlated interference due to scattering by nearby bubbles. The incident acoustic field is taken to be locally planar. Bubble scattering contributions to the interference field are calculated using the single scattering approximation of Ishimaru (1977, Chap. 6) assuming contributions by resonant bubbles only. Comparison is made between the acoustic effects of homogeneous and inhomogeneous (clumpy) distributions of bubbles. One feature of this work is that bubble distribution can be generated using computational fluid dynamics calculations for a fluid field and momentum transport equations for the bubbles. [Work sponsored by Office of Naval Research, Code 321 Undersea Signal Processing.]
New techniques for measuring speech privacy and efficiency of sound masking systems
Authors: Mapp Peter
Published: October 2013

Traditionally, speech privacy has been measured by means of the Articulation Index (AI), transposed to rate privacy rather than intelligibility (PI=1-AI). However, this is an indirect and slightly cumbersome method that usually requires a spreadsheet calculation to yield the Privacy Index rating. Furthermore, the traditional AI approach does not take into account room reverberation effects (though the very much more complex SII does). The paper discusses the potential use of STI and STIPa as direct measures of speech privacy and shows that, potentially, they may be able to offer a superior approach. The benefits and limitations of the methods are highlighted together with the results from a number of case studies. It is concluded that while the method has potential merit, a number of the limiting factors require further research. It particular, it is shown that the index scale at lower levels of intelligibility may need to be revised.
A case study in measuring speech privacy in a flexible closed/open space
Authors: Good Kenneth
Published: October 2013

When we think about speech privacy we often think about the typical open plan office cubical or a small closed room such as a healthcare exam room. But an opportunity arose for an interesting case study with potential twists to the typical projects. This case study is for a flexible space within a church where a large common open room is used. This room is then divided off into several medium-sized Sunday school or meeting rooms in much the same concept as a hotel conference area—but with smaller rooms and low ceilings. The desire for privacy is to both minimize distraction from the adjacent space and provide a high level of confidentiality for sensitive conversations. This case study will explore the unique challenges in meeting and qualifying privacy expectations for this space.
Jamming avoidance reveals segregation of processing for detection and ranging in echolocating bats
Authors: Simmons James A. , Bates Mary , Stamper Sarah
Published: October 2013

Big brown bats emit frequency-modulated (FM) biosonar sounds that sweep from 50 to 23 kHz in the first harmonic. When searching for targets in the open or when detecting targets in wideband noise, bats lengthen their sounds and allow the FM sweep to tail off into a nearly constant-frequency (CF) segment, which boosts the energy in the sound over a narrow band of 24–28 kHz. When detecting a target in CF jamming sounds, bats shift their emitted frequencies up or down to move this terminal CF component from the interference when the CF frequency is 23–27 kHz. Other researchers have found a population of neurons in the bats inferior colliculus that is sharply tuned (Q10dB=30–40) to frequencies of 24–30 kHz and may be used to detect echoes. However, these same frequencies also contribute incrementally to determining echo-delay accuracy for target ranging, and a parallel population of neurons has only moderately sharp tuning (Q10dB <5–10). Sharper tuning in the cochlea might facilitate detection but could compromise time constants for reception, so these bats use neuronal inhibition in the inferior colliculus to create two parallel receivers at frequencies of 24–30 kHz. [Work supported by ONR and NIH.]
Rules-based front-end detector as a bootstrap method for model-based detection of microchiropteran calls
Authors: Skowronski Mark , Fenton Brock
Published: October 2013

Rules-based methods for automated acoustical signal processing of bat calls have been developed throughout the history of bat acoustics research, stemming from techniques developed by expert acousticians for hand analysis of bat calls. Recently, a model-based paradigm [Skowronski and Harris, J. Acoust. Soc. Am. 119(3), 1817–1833 (2006)], inspired by automatic speech recognition research, was introduced that improved the accuracy of detection and classification of echolocation calls by an order of magnitude over conventional techniques. However, the models require labeled data for training, and generating call end points by hand is time consuming and labor intensive. As an alternative, a rules-based front-end detector was developed to provide initial call end points for detection models. The combined system allows the models to be trained with unlabeled data, which greatly reduces the amount of time and effort needed to produce accurate detection models. With a sufficient amount of training data from across the spectrum of bat species, the model-based detector is superior to the rules-based detector and also generalizes to calls from species not present in the training data.
The acoustic function of flaps and furrows in the noseleaves of horseshoe bats
Authors: Müller Rolf , Zhuang Qiao , Wang Fuxun
Published: October 2013

The nostrils of horseshoe bats are surrounded by elaborate noseleaves which consist of three parts: anterior leaf, sella, and lancet. Of these parts, shape and location of the anterior leaf, which forms a baffle around the nostrils, are most suggestive of an acoustic function. While such an argument is not as readily made for them, the other two parts show more conspicuous structural features than the anterior leaf. In particular, the lancet is furrowed by deep horizontal grooves in most species and flaps can be attached to the bottom of the lancet in some species. The results of a numerical analysis presented here indicate that the lancet furrows and the sella flaps both have effects on the animals’ radiation pattern. The acoustic mechanisms behind these effects differ; however, Lancet furrows act as half-open resonance cavities whereas the sella flaps have a more complicated impact on the wavefield phase and amplitude. Despite the differences in the acoustic mechanisms, there are two important commonalities in the effects of these structural features: Both act as devices for beam dispersal widening the distribution of sound energy over angle and the effects of both are limited to the FM-component of the biosonar pulse.
Experiments on the origin of breaking wave noise
Authors: Deane Grant B.
Published: October 2013

The origin of wave noise has been of interest since the works of Wenz and Knudsen in the first half of the last century and remains an active area of research. Medwin made seminal contributions to this topic. His measurements of the sound generated by gently spilling breakers, along with those of Banner and Cato, settled the question of the origin of the noise: bubbles. An issue that remains unresolved is the nature of the excitation mechanism at bubble formation leading to acoustic emission. This will be discussed along with some recent laboratory measurements of fragmenting bubbles. [Work supported by ONR.]
Medwin’s maxim for finding good research questions: Listen to your students. Or a freshman’s approach to shallow water acoustics
Authors: Colosi John
Published: October 2013

Over the years, Hank Medwin worked with numerous students and postdoctoral scientists, making fundamental discoveries in almost every branch of ocean acoustics. Hank’s motivations were not so altruistic, but were based on a deep appreciation for the fact that young scientists would ask simple questions that the more seasoned scientist often did not. As a young faculty member of the Naval Postgraduate School, Hank wasted no time in passing this information onto me, the result of which is the freshman’s approach to shallow water acoustics discussed in this talk.
Hypotheses on the exploitation of bubble acoustics by cetaceans
Authors: Leighton Timothy , Finfer Daniel , White Paul
Published: October 2013

Man-made sonar does not operate well in bubbly water, and yet cetaceans not only function effectively in shallow coastal waters, but also at times generate large bubble fields to assist with catching prey. This paper outlines the challenges faced by cetaceans in using acoustics in such environments, and proposes acoustical techniques which would work. The validity of such proposed acoustical solutions is explored through theory, simulation, and experimentation. The scenarios in question relate to the circular and spiral bubble nets generated to trap prey by humpback whales, and solutions to difficulties associated with echolocation by dolphins and porpoises in bubbly water. Whether the solutions are exploited by cetaceans is uncertain, but their efficacy in test tanks and implications for man-made sonar are demonstrated.
Sorting out the racket: Acoustic footprints for ocean climate
Authors: Nystuen Jeffrey A.
Published: October 2013

Ocean ambient sound is a component of the physical marine environment that contains quantifiable information about physical processes, and patterns of biological and anthropogenic activity. Sorting out the different sound sources is a necessary component for utilizing ambient sound to monitor the environment. Hank Medwin played a fundamental role investigating the micro-physics of sound production by breaking waves and raindrops. These two sound sources, wind and rain, form the basis for distinctive acoustic footprints for different marine environments. During the past decade, passive aquatic listeners have been deployed from moorings in many different marine environments including deep ocean locations (SE Pacific, NE Pacific, Eastern and Western tropical Pacific), marginal seas (Bering and Ionian), and coastal/inland waterways (Cape Flattery, Puget Sound). Sound budgets developed for these different marine environments show distinctive patterns associated with different types of rainfall and storms present, and contain distinctive patterns of biological and anthropogenic activities. These sound budgets quantify acoustic ocean climate and can be used to monitor future changes in the marine environment. [Work supported by ONR Ocean Acoustics and NSF Physical Oceanography.]
Herman Medwin and forward scattering from rough surfaces near grazing incidence
Authors: D’Spain Gerald L.
Published: October 2013

Herman Medwin, ‘‘The Professor,’’ was a man of great energy who thrived on getting things done. One small indication of that were the athletic shoes he wore with his sports coat and tie when he attended Acoustical Society of America meetings; they allowed him to stay ‘‘on the run.’’ I worked with him and Ocean Acoustics Associates for a 3 year period in the early 1980’s. Our major research efforts then were devoted to laboratory-scale measurements of sound scattering from rough surfaces, in particular forward scattering near grazing incidence at low frequencies. A significant amount of the research was conducted by U.S. Navy officers in the physics department at the Naval Postgraduate School. The Professor had a gift of organizing the work into 6 month blocks appropriate for each student’s master’s thesis. A number of distinguished civilian scientists also passed through the laboratory. He was tremendously proud of Fundamentals of Acoustical Oceanography and liked to say that the book, co-authored with his friend Clarence Clay, put him on the map. In the Acknowledgments in my Ph.D. thesis appears the sentence [‘‘I want to specially thank The Professor, Herman Medwin, who helped put the fun back into science.’’]
Numerical modeling of groundfish target strength compared to in situ data
Authors: Sarangapani Sairajan , Miksis-Olds Jennifer L. , Reeder D. Benjamin
Published: October 2013

Acoustic scattering models of zooplankton and fish are an essential component of the process of converting in situ target strength of marine organisms into meaningful biological parameters such as size and numerical density. This study compared the numerical model of axisymmetrically shaped groundfish target strength (e.g., cod, dog fish, haddock) with measurements obtained in situ. Experimental target strength data were obtained using a bottom-mounted 200-kHz acoustical platform, fitted with four laser beams and an optical recording system to correlate species, length, and incidence angle to the measured target strength. Based on the length of the groundfish obtained from the data in situ, target strength modeling estimates were computed using the FMM (Fourier matching method), assuming an axisymmetrically shaped swim bladder with soft boundary conditions. The scattering coefficients for the truncated modal series solutions were predicted in quad precision, which added stability to the results. Data-model comparisons of target strength at 200 kHz are presented as a function of incidence angle for a number of groundfish of different lengths and species. [Work supported by NOAA.]
Mining in the U.S. Rocky Mountain West (circa 2007) and its environmental noise implications
Authors: Hankard Michael , Cerjan Jeff
Published: October 2013

There’s gold in them hills, and some oil, gas, and coal, too. Commodity prices are up, the desire to develop domestic energy supplies is strong, and the West has some (relatively) green fuels to be had. The relevance of this to acoustics is that it takes a lot of big, noisy equipment to get these resources to market. This, combined with the construction of homes advancing further into prime mining lands, tends to create noise conflicts between landowners and mineral rights owners. This study identifies the locations of existing mining operations in the West, and looks at which sectors are on the rise. The major noise producing activities associated with various mining activities are described, including earth moving, processing, transportation, and blast noise and vibration. A review of noise propagation models, applicable environmental noise regulations, and mitigation strategies is also provided. This report is intended to be a useful reference for those interested in gaining an understanding of the location and nature of current and projected mining operations in the U.S. West, the noise generated by these operations, and how noise conflicts between mining and homeowners are being addressed.
Noise controls for drills in the dimension stone industry
Authors: Argirakis Anthony S.
Published: October 2013

Drills in the dimension stone industry have proven to be a problem when it comes to overexposures to noise. These drills include, but are not limited to slot drills, down-hole drills, and horizontal lift-hole drills. Although drills with acoustically treated operator cabs exist for this industry, most drills encountered do not have them. Considerable effort has been made by both the Mine Safety and Health Administration (MSHA) and industry to achieve compliance with the noise standards stated in Code of Federal Regulations (CFR) Title 30, part 62 for the drills without operator cabs. Several individual noise controls are available for these drills. They include exhaust mufflers, operator control barriers, hammer covers, face shields, and three-sided enclosures. A joint noise study was conducted by MSHA and a cooperative mining company to determine the effectiveness of these individual noise controls alone and in various combinations. Previously, these noise controls were studied separately under varying conditions and some found to provide significant noise reductions. The study was conducted to determine their effectiveness under the same conditions and to quantify not only their reduction in sound level, but also overall noise dose.