bluuebunny/crossref_metadata_2025 huggingface dataset:
Subharmonic tonal noise from backflow vortices radiated by a low-speed ring fan in uniform inlet flow
Authors: Magne Stéphan , Moreau Stéphane , Berry Alain
Published: January 2015

In order to highlight the mechanisms responsible for subharmonic tonal noise, a complete aeroacoustic study of a ring fan in presence of a uniform inlet flow is conducted. Unsteady RANS simulations with a compressible flow solver are used to compute the flow field and identify the acoustic sources on the rotor. The tip clearance recirculation shows upstream vortices that impinge the rotor blades and create the main source of unsteadiness on the fan. Since these vortices rotate at a lower speed than the rotor, the frequency of the impact is lower than the blade passing frequency. The acoustic signature is computed by propagating the noise sources located on the rotor surfaces using two methods: A Ffowcs-Williams and Hawkings analogy in the time-domain and an analytical model in the frequency-domain based on the compact rotating dipole formulation. A comparison with experimental results confirms that the aeroacoustic phenomena responsible for the subharmonic tonal noise are well captured and properly propagated by the acoustic codes.
Automated acoustic localization and call association for vocalizing humpback whales on the Navy's Pacific Missile Range Facility
Authors: Helble Tyler A. , Ierley Glenn R. , D'Spain Gerald L. , Martin Stephen W.
Published: January 2015

Time difference of arrival (TDOA) methods for acoustically localizing multiple marine mammals have been applied to recorded data from the Navy's Pacific Missile Range Facility in order to localize and track humpback whales. Modifications to established methods were necessary in order to simultaneously track multiple animals on the range faster than real-time and in a fully automated way, while minimizing the number of incorrect localizations. The resulting algorithms were run with no human intervention at computational speeds faster than the data recording speed on over forty days of acoustic recordings from the range, spanning multiple years. Spatial localizations based on correlating sequences of units originating from within the range produce estimates having a standard deviation typically 10 m or less (due primarily to TDOA measurement errors), and a bias of 20 m or less (due primarily to sound speed mismatch). An automated method for associating units to individual whales is presented, enabling automated humpback song analyses to be performed.
Active control of sound transmission through a rectangular panel using point-force actuators and piezoelectric film sensors
Authors: Sanada Akira , Higashiyama Kouji , Tanaka Nobuo
Published: January 2015

This study deals with the active control of sound transmission through a rectangular panel, based on single input, single output feedforward vibration control using point-force actuators and piezoelectric film sensors. It focuses on the phenomenon in which the sound power transmitted through a finite-sized panel drops significantly at some frequencies just below the resonance frequencies of the panel in the low-frequency range as a result of modal coupling cancellation. In a previous study, it was shown that when point-force actuators are located on nodal lines for the frequency at which this phenomenon occurs, a force equivalent to the incident sound wave can act on the panel. In this study, a practical method for sensing volume velocity using a small number of piezoelectric film strips is investigated. It is found that two quadratically shaped piezoelectric film strips, attached at the same nodal lines as those where the actuators were placed, can sense the volume velocity approximately in the low-frequency range. Results of simulations show that combining the proposed actuation method and the sensing method can achieve a practical control effect at low frequencies over a wide frequency range. Finally, experiments are carried out to demonstrate the validity and feasibility of the proposed method.
Compensating for the effects of site and equipment variation on delphinid species identification from their echolocation clicks
Authors: Roch Marie A. , Stinner-Sloan Johanna , Baumann-Pickering Simone , Wiggins Sean M.
Published: January 2015

A concern for applications of machine learning techniques to bioacoustics is whether or not classifiers learn the categories for which they were trained. Unfortunately, information such as characteristics of specific recording equipment or noise environments can also be learned. This question is examined in the context of identifying delphinid species by their echolocation clicks. To reduce the ambiguity between species classification performance and other confounding factors, species whose clicks can be readily distinguished were used in this study: Pacific white-sided and Risso's dolphins. A subset of data from autonomous acoustic recorders located at seven sites in the Southern California Bight collected between 2006 and 2012 was selected. Cepstral-based features were extracted for each echolocation click and Gaussian mixture models were used to classify groups of 100 clicks. One hundred Monte-Carlo three-fold experiments were conducted to examine classification performance where fold composition was determined by acoustic encounter, recorder characteristics, or recording site. The error rate increased from 6.1% when grouped by acoustic encounter to 18.1%, 46.2%, and 33.2% for grouping by equipment, equipment category, and site, respectively. A noise compensation technique reduced error for these grouping schemes to 2.7%, 4.4%, 6.7%, and 11.4%, respectively, a reduction in error rate of 56%–86%.
High-resolution bottom-loss estimation using the ambient-noise vertical coherence function
Authors: Muzi Lanfranco , Siderius Martin , Quijano Jorge E. , Dosso Stan E.
Published: January 2015

The seabed reflection loss (shortly “bottom loss”) is an important quantity for predicting transmission loss in the ocean. A recent passive technique for estimating the bottom loss as a function of frequency and grazing angle exploits marine ambient noise (originating at the surface from breaking waves, wind, and rain) as an acoustic source. Conventional beamforming of the noise field at a vertical line array of hydrophones is a fundamental step in this technique, and the beamformer resolution in grazing angle affects the quality of the estimated bottom loss. Implementation of this technique with short arrays can be hindered by their inherently poor angular resolution. This paper presents a derivation of the bottom reflection coefficient from the ambient-noise spatial coherence function, and a technique based on this derivation for obtaining higher angular resolution bottom-loss estimates. The technique, which exploits the (approximate) spatial stationarity of the ambient-noise spatial coherence function, is demonstrated on both simulated and experimental data.
Uncertainty analysis of standardized measurements of random-incidence absorption and scattering coefficients
Authors: Müller-Trapet Markus , Vorländer Michael
Published: January 2015

This work presents an analysis of the effect of some uncertainties encountered when measuring absorption or scattering coefficients in the reverberation chamber according to International Organization for Standardization/American Society for Testing and Materials standards. This especially relates to the uncertainty due to spatial fluctuations of the sound field. By analyzing the mathematical definition of the respective coefficient, a relationship between the properties of the chamber and the test specimen and the uncertainty in the measured quantity is determined and analyzed. The validation of the established equations is presented through comparisons with measurement data. This study analytically explains the main sources of error and provides a method to obtain the product of the necessary minimum number of measurement positions and the band center frequency to achieve a given maximum uncertainty in the desired quantity. It is shown that this number depends on the ratio of room volume to sample surface area and the reverberation time of the empty chamber.
Chinese speech intelligibility and its relationship with the speech transmission index for children in elementary school classrooms
Authors: Peng Jianxin , Yan Nanjie , Wang Dan
Published: January 2015

The present study investigated Chinese speech intelligibility in 28 classrooms from nine different elementary schools in Guangzhou, China. The subjective Chinese speech intelligibility in the classrooms was evaluated with children in grades 2, 4, and 6 (7 to 12 years old). Acoustical measurements were also performed in these classrooms. Subjective Chinese speech intelligibility scores and objective speech intelligibility parameters, such as speech transmission index (STI), were obtained at each listening position for all tests. The relationship between subjective Chinese speech intelligibility scores and STI was revealed and analyzed. The effects of age on Chinese speech intelligibility scores were compared. Results indicate high correlations between subjective Chinese speech intelligibility scores and STI for grades 2, 4, and 6 children. Chinese speech intelligibility scores increase with increase of age under the same STI condition. The differences in scores among different age groups decrease as STI increases. To achieve 95% Chinese speech intelligibility scores, the STIs required for grades 2, 4, and 6 children are 0.75, 0.69, and 0.63, respectively.
Cross-correlation, triangulation, and curved-wavefront focusing of coral reef sound using a bi-linear hydrophone array
Authors: Freeman Simon E. , Buckingham Michael J. , Freeman Lauren A. , Lammers Marc O. , D'Spain Gerald L.
Published: January 2015

A seven element, bi-linear hydrophone array was deployed over a coral reef in the Papahãnaumokuãkea Marine National Monument, Northwest Hawaiian Islands, in order to investigate the spatial, temporal, and spectral properties of biological sound in an environment free of anthropogenic influences. Local biological sound sources, including snapping shrimp and other organisms, produced curved-wavefront acoustic arrivals at the array, allowing source location via focusing to be performed over an area of 1600 m2. Initially, however, a rough estimate of source location was obtained from triangulation of pair-wise cross-correlations of the sound. Refinements to these initial source locations, and source frequency information, were then obtained using two techniques, conventional and adaptive focusing. It was found that most of the sources were situated on or inside the reef structure itself, rather than over adjacent sandy areas. Snapping-shrimp-like sounds, all with similar spectral characteristics, originated from individual sources predominantly in one area to the east of the array. To the west, the spectral and spatial distributions of the sources were more varied, suggesting the presence of a multitude of heterogeneous biological processes. In addition to the biological sounds, some low-frequency noise due to distant breaking waves was received from end-fire north of the array.
Treatment of a sloping fluid-solid interface and sediment layering with the seismo-acoustic parabolic equation
Authors: Collins Michael D. , Siegmann William L.
Published: January 2015

The parabolic equation method is extended to handle problems in seismo-acoustics that have multiple fluid and solid layers, continuous depth dependence within layers, and sloping interfaces between layers. The medium is approximated in terms of a series of range-independent regions, and a single-scattering approximation is used to compute transmitted fields across the vertical interfaces between regions. The approach is implemented in terms of a set of dependent variables that is well suited to piecewise continuous depth dependence in the elastic parameters, but one of the fluid-solid interface conditions in that formulation involves a second derivative that complicates the treatment of sloping interfaces. This issue is resolved by using a non-centered, four-point difference formula for the second derivative. The approach is implemented using a matrix decomposition that is efficient when the parameters of the medium have a general dependence within the upper layers of the sediment but only depend on depth in the water column and deep within the sediment.
A survey of acoustic conditions and noise levels in secondary school classrooms in England
Authors: Shield Bridget , Conetta Robert , Dockrell Julie , Connolly Daniel , Cox Trevor , Mydlarz Charles
Published: January 2015

An acoustic survey of secondary schools in England has been undertaken. Room acoustic parameters and background noise levels were measured in 185 unoccupied spaces in 13 schools to provide information on the typical acoustic environment of secondary schools. The unoccupied acoustic and noise data were correlated with various physical characteristics of the spaces. Room height and the amount of glazing were related to the unoccupied reverberation time and therefore need to be controlled to reduce reverberation to suitable levels for teaching and learning. Further analysis of the unoccupied data showed that the introduction of legislation relating to school acoustics in England and Wales in 2003 approximately doubled the number of school spaces complying with current standards. Noise levels were also measured during 274 lessons to examine typical levels generated during teaching activities in secondary schools and to investigate the influence of acoustic design on working noise levels in the classroom. Comparison of unoccupied and occupied data showed that unoccupied acoustic conditions affect the noise levels occurring during lessons. They were also related to the time spent in disruption to the lessons (e.g., students talking or shouting) and so may also have an impact upon student behavior in the classroom.
Equivalence of time and aperture domain additive noise in ultrasound coherence
Authors: Bottenus Nick B. , Trahey Gregg E.
Published: January 2015

Ultrasonic echoes backscattered from diffuse media, recorded by an array transducer and appropriately focused, demonstrate coherence predicted by the van Cittert–Zernike theorem. Additive noise signals from off-axis scattering, reverberation, phase aberration, and electronic (thermal) noise can all superimpose incoherent or partially coherent signals onto the recorded echoes, altering the measured coherence. An expression is derived to describe the effect of uncorrelated random channel noise in terms of the noise-to-signal ratio. Equivalent descriptions are made in the aperture dimension to describe uncorrelated magnitude and phase apodizations of the array. Binary apodization is specifically described as an example of magnitude apodization and adjustments are presented to minimize the artifacts caused by finite signal length. The effects of additive noise are explored in short-lag spatial coherence imaging, an image formation technique that integrates the calculated coherence curve of acquired signals up to a small fraction of the array length for each lateral and axial location. A derivation of the expected contrast as a function of noise-to-signal ratio is provided and validation is performed in simulation.
Mixing of two co-directional Rayleigh surface waves in a nonlinear elastic material
Authors: Morlock Merlin B. , Kim Jin-Yeon , Jacobs Laurence J. , Qu Jianmin
Published: January 2015

The mixing of two co-directional, initially monochromatic Rayleigh surface waves in an isotropic, homogeneous, and nonlinear elastic solid is investigated using analytical, finite element method, and experimental approaches. The analytical investigations show that while the horizontal velocity component can form a shock wave, the vertical velocity component can form a pulse independent of the specific ratios of the fundamental frequencies and amplitudes that are mixed. This analytical model is then used to simulate the development of the fundamentals, second harmonics, and the sum and difference frequency components over the propagation distance. The analytical model is further extended to include diffraction effects in the parabolic approximation. Finally, the frequency and amplitude ratios of the fundamentals are identified which provide maximum amplitudes of the second harmonics as well as of the sum and difference frequency components, to help guide effective material characterization; this approach should make it possible to measure the acoustic nonlinearity of a solid not only with the second harmonics, but also with the sum and difference frequency components. Results of the analytical investigations are then confirmed using the finite element method and the experimental feasibility of the proposed technique is validated for an aluminum specimen.
Musicians and non-musicians are equally adept at perceiving masked speech
Authors: Boebinger Dana , Evans Samuel , Rosen Stuart , Lima César F. , Manly Tom , Scott Sophie K.
Published: January 2015

There is much interest in the idea that musicians perform better than non-musicians in understanding speech in background noise. Research in this area has often used energetic maskers, which have their effects primarily at the auditory periphery. However, masking interference can also occur at more central auditory levels, known as informational masking. This experiment extends existing research by using multiple maskers that vary in their informational content and similarity to speech, in order to examine differences in perception of masked speech between trained musicians (n = 25) and non-musicians (n = 25). Although musicians outperformed non-musicians on a measure of frequency discrimination, they showed no advantage in perceiving masked speech. Further analysis revealed that non-verbal IQ, rather than musicianship, significantly predicted speech reception thresholds in noise. The results strongly suggest that the contribution of general cognitive abilities needs to be taken into account in any investigations of individual variability for perceiving speech in noise.
The role of recovered envelope cues in the identification of temporal-fine-structure speech for hearing-impaired listeners
Authors: Léger Agnès C. , Desloge Joseph G. , Braida Louis D. , Swaminathan Jayaganesh
Published: January 2015

Narrowband speech can be separated into fast temporal cues [temporal fine structure (TFS)], and slow amplitude modulations (envelope). Speech processed to contain only TFS leads to envelope recovery through cochlear filtering, which has been suggested to account for TFS-speech intelligibility for normal-hearing listeners. Hearing-impaired listeners have deficits with TFS-speech identification, but the contribution of recovered-envelope cues to these deficits is unknown. This was assessed for hearing-impaired listeners by measuring identification of disyllables processed to contain TFS or recovered-envelope cues. Hearing-impaired listeners performed worse than normal-hearing listeners, but TFS-speech intelligibility was accounted for by recovered-envelope cues for both groups.
The subjective effect of low frequency content in road traffic noise
Authors: Torija Antonio J. , Flindell Ian H.
Published: January 2015

Based on subjective listening trials, Torija and Flindell [J. Acoust. Soc. Am. 135, 1–4 (2014)] observed that low frequency content in typical urban main road traffic noise appeared to make a smaller contribution to reported annoyance than might be inferred from its objective or physical dominance. This paper reports a more detailed study which was aimed at (i) identifying the difference in sound levels at which low frequency content becomes subjectively dominant over mid and high frequency content and (ii) investigating the relationship between loudness and annoyance under conditions where low frequency content is relatively more dominant, such as indoors where mid and high frequency content is reduced. The results suggested that differences of at least +30 dB between the low frequency and the mid/high frequency content are needed for changes in low frequency content to have as much subjective effect as equivalent changes in mid and high frequency content. This suggests that common criticisms of the A-frequency weighting based on a hypothesized excessive downweighting of the low frequency content may be relatively unfounded in this application area.
Optimal virtual mechanical impedances for the vibroacoustic active control of a thin plate
Authors: Michau M. , Berry A. , Micheau Ph. , Herzog Ph.
Published: January 2015

In order to reduce the acoustic power radiated by a flexible panel, dual colocated actuator / sensor pairs are used to modify its vibration. The control strategy implemented for harmonic disturbances leads to locally impose a virtual mechanical impedance to the structure, using the linear relation between the actuator input and the control output of each pair. This virtual mechanical impedance is computed in order to minimize the radiated acoustic power. The proposed approach consists in two steps: (1) the matrix of optimal virtual mechanical impedance is calculated by measuring the primary disturbance and the transfer functions between actuators and structural/acoustic sensors and (2) the virtual mechanical impedance objective is achieved using a real-time integral controller. It is shown that such an optimal control approach leads to better sound power reduction than a classical active damping strategy where the virtual mechanical impedance is defined as real positive. Theoretical and experimental results are compared, also showing that the method proposed here is robust regarding variations of the primary disturbance.
Low frequency baleen whale calls detected on ocean-bottom seismometers in the Lau basin, southwest Pacific Ocean
Authors: Brodie Dana C. , Dunn Robert A.
Published: January 2015

Ten months of broadband seismic data, recorded on six ocean-bottom seismographs located in the Lau Basin, were examined to identify baleen whale species. As the first systematic survey of baleen whales in this part of the southwest Pacific Ocean, this study reveals the variety of species present and their temporal occurrence in and near the basin. Baleen whales produce species-specific low frequency calls that can be identified by distinct patterns in data spectrograms. By matching spectrograms with published accounts, fin, Bryde's, Antarctic blue, and New Zealand blue whale calls were identified. Probable whale sounds that could not be matched to published spectrograms, as well as non-biologic sounds that are likely of volcanogenic origin, were also recorded. Detections of fin whale calls (mid-June to mid-October) and blue whale calls (June through September) suggest that these species migrate through the region seasonally. Detections of Bryde's whale calls (primarily February to June, but also other times of the year) suggest this species resides around the basin nearly year round. The discovery of previously unpublished call types emphasizes the limited knowledge of the full call repertoires of baleen whales and the utility of using seismic survey data to enhance understanding in understudied regions.
ACOUSTICAL STANDARDS NEWS
Authors: Blaeser Susan B. , Schomer Paul D.
Published: January 2015

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes catalogs of Acoustical Standards, both National and International. To receive copies of the latest Standards catalogs, please contact Susan B. Blaeser.

Comments are welcomed on all material in Acoustical Standards News.

This Acoustical Standards News section in JASA, as well as the National and International Catalogs of Acoustical Standards, and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org.
Different Bacterial Populations Associated with the Roots and Rhizosphere of Rice Incorporate Plant-Derived Carbon
Authors: Hernández Marcela , Dumont Marc G. , Yuan Quan , Conrad Ralf
Published: January 2015

Microorganisms associated with the roots of plants have an important function in plant growth and in soil carbon sequestration. Rice cultivation is the second largest anthropogenic source of atmospheric CH
4
, which is a significant greenhouse gas. Up to 60% of fixed carbon formed by photosynthesis in plants is transported below ground, much of it as root exudates that are consumed by microorganisms. A stable isotope probing (SIP) approach was used to identify microorganisms using plant carbon in association with the roots and rhizosphere of rice plants. Rice plants grown in Italian paddy soil were labeled with
13
CO
2
for 10 days. RNA was extracted from root material and rhizosphere soil and subjected to cesium gradient centrifugation followed by 16S rRNA amplicon pyrosequencing to identify microorganisms enriched with
13
C. Thirty operational taxonomic units (OTUs) were labeled and mostly corresponded to
Proteobacteria
(13 OTUs) and
Verrucomicrobia
(8 OTUs). These OTUs were affiliated with the
Alphaproteobacteria
,
Betaproteobacteria
, and
Deltaproteobacteria
classes of
Proteobacteria
and the “
Spartobacteria
” and
Opitutae
classes of
Verrucomicrobia
. In general, different bacterial groups were labeled in the root and rhizosphere, reflecting different physicochemical characteristics of these locations. The labeled OTUs in the root compartment corresponded to a greater proportion of the 16S rRNA sequences (∼20%) than did those in the rhizosphere (∼4%), indicating that a proportion of the active microbial community on the roots greater than that in the rhizosphere incorporated plant-derived carbon within the time frame of the experiment.
Syntrophic Growth of Desulfovibrio alaskensis Requires Genes for H
2
and Formate Metabolism as Well as Those for Flagellum and Biofilm Formation
Authors: Krumholz Lee R. , Bradstock Peter , Sheik Cody S. , Diao Yiwei , Gazioglu Ozcan , Gorby Yuri , McInerney Michael J.
Published: January 2015

In anaerobic environments, mutually beneficial metabolic interactions between microorganisms (syntrophy) are essential for oxidation of organic matter to carbon dioxide and methane. Syntrophic interactions typically involve a microorganism degrading an organic compound to primary fermentation by-products and sources of electrons (i.e., formate, hydrogen, or nanowires) and a partner producing methane or respiring the electrons via alternative electron accepting processes. Using a transposon gene mutant library of the sulfate-reducing
Desulfovibrio alaskensis
G20, we screened for mutants incapable of serving as the electron-accepting partner of the butyrate-oxidizing bacterium,
Syntrophomonas wolfei
. A total of 17 gene mutants of
D. alaskensis
were identified as incapable of serving as the electron-accepting partner. The genes identified predominantly fell into three categories: membrane surface assembly, flagellum-pilus synthesis, and energy metabolism. Among these genes required to serve as the electron-accepting partner, the glycosyltransferase, pilus assembly protein (
tadC
), and flagellar biosynthesis protein showed reduced biofilm formation, suggesting that each of these components is involved in cell-to-cell interactions. Energy metabolism genes encoded proteins primarily involved in H
2
uptake and electron cycling, including a rhodanese-containing complex that is phylogenetically conserved among sulfate-reducing
Deltaproteobacteria
. Utilizing an mRNA sequencing approach, analysis of transcript abundance in wild-type axenic and cocultures confirmed that genes identified as important for serving as the electron-accepting partner were more highly expressed under syntrophic conditions. The results imply that sulfate-reducing microorganisms require flagellar and outer membrane components to effectively couple to their syntrophic partners; furthermore, H
2
metabolism is essential for syntrophic growth of
D. alaskensis
G20.
The Global Regulator CodY in Streptococcus thermophilus Controls the Metabolic Network for Escalating Growth in the Milk Environment
Authors: Lu W. W. , Wang Y. , Wang T. , Kong J.
Published: January 2015

CodY is a transcriptional regulator conserved in the low-GC group of Gram-positive bacteria. In this work, we demonstrated the presence in
Streptococcus thermophilus
ST2017 of a functional member of the CodY family of global regulatory proteins,
S. thermophilus
CodY (CodY
St
). The CodY
St
regulon was identified by transcriptome analysis; it consisted predominantly of genes involved in amino acid metabolism but also included genes involved in several other cellular processes, including carbon metabolism, nutrient transport, and stress response. It was revealed that CodY
St
repressed the transformation of the central metabolic pathway to amino acid metabolism and improved lactose utilization. Furthermore, the glutamate dehydrogenase gene (
gdhA
), repressed by CodY
St
, was suggested to coordinate the interconversion between carbon metabolism and amino acid metabolism and to play an important role on the optimal growth of
S. thermophilus
ST2017 in milk. A conserved CodY
St
box [AA(T/A)(A/T)TTCTGA(A/C)AATT] was indeed required for
in vitro
binding of CodY
St
to the target regions of DNA. These results provided evidence for the function of CodY
St
, by which this strain coordinately regulates its various metabolic pathways so as to adapt to the milk environment.
Anthranilate Deteriorates the Structure of Pseudomonas aeruginosa Biofilms and Antagonizes the Biofilm-Enhancing Indole Effect
Authors: Kim Soo-Kyoung , Park Ha-Young , Lee Joon-Hee
Published: January 2015

Anthranilate and indole are alternative degradation products of tryptophan, depending on the bacterial species. While indole enhances the biofilm formation of
Pseudomonas aeruginosa
, we found that anthranilate, the tryptophan degradation product of
P. aeruginosa
, had an opposite effect on
P. aeruginosa
biofilm formation, in which anthranilate deteriorated the mushroom structure of biofilm. The anthranilate effect on biofilm formation was differentially exerted depending on the developmental stage and the presence of shear force. Anthranilate slightly accelerated the initial attachment of
P. aeruginosa
at the early stage of biofilm development and appeared to build more biofilm without shear force. But anthranilate weakened the biofilm structure in the late stage, deteriorating the mushroom structure of biofilms with shear force to make a flat biofilm. To investigate the interplay of anthranilate with indole in biofilm formation, biofilms were cotreated with anthranilate and indole, and the results showed that anthranilate antagonized the biofilm-enhancing effect of indole. Anthranilate was able to deteriorate the preformed biofilm. The effect of anthranilate and indole on biofilm formation was quorum sensing independent. AntR, a regulator of anthranilate-degrading metabolism was synergistically activated by cotreatment with anthranilate and indole, suggesting that indole might enhance biofilm formation by facilitating the degradation of anthranilate. Anthranilate slightly but significantly affected the cyclic diguaniylate (c-di-GMP) level and transcription of major extracellular polysaccharide (Psl, Pel, and alginate) operons. These results suggest that anthranilate may be a promising antibiofilm agent and antagonize the effect of indole on
P. aeruginosa
biofilm formation.
Extrahuman Epidemiology of Acinetobacter baumannii in Lebanon
Authors: Rafei Rayane , Hamze Monzer , Pailhoriès Hélène , Eveillard Matthieu , Marsollier Laurent , Joly-Guillou Marie-Laure , Dabboussi Fouad , Kempf Marie
Published: January 2015

The presence of
Acinetobacter baumannii
outside hospitals is still a controversial issue. The objective of our study was to explore the extrahospital epidemiology of
A. baumannii
in Lebanon. From February 2012 to October 2013, a total of 73 water samples, 51 soil samples, 37 raw cow milk samples, 50 cow meat samples, 7 raw cheese samples, and 379 animal samples were analyzed by cultural methods for the presence of
A. baumannii
. Species identification was performed by
rpoB
gene sequencing. Antibiotic susceptibility was investigated, and the
A. baumannii
population was studied by two genotyping approaches: multilocus sequence typing (MLST) and
bla
OXA-51
sequence-based typing (SBT).
A. baumannii
was detected in 6.9% of water samples, 2.7% of milk samples, 8.0% of meat samples, 14.3% of cheese samples, and 7.7% of animal samples. All isolates showed a susceptible phenotype against most of the antibiotics tested and lacked carbapenemase-encoding genes, except one that harbored a
bla
OXA-143
gene. MLST analysis revealed the presence of 36 sequence types (STs), among which 24 were novel STs reported for the first time in this study.
bla
OXA-51
SBT showed the presence of 34 variants, among which 21 were novel and all were isolated from animal origins. Finally, 30 isolates had new partial
rpoB
sequences and were considered putative new
Acinetobacter
species. In conclusion, animals can be a potential reservoir for
A. baumannii
and the dissemination of new emerging carbapenemases. The roles of the novel animal clones identified in community-acquired infections should be investigated.
Long-Term Study of Vibrio parahaemolyticus Prevalence and Distribution in New Zealand Shellfish
Authors: Cruz C. D. , Hedderley D. , Fletcher G. C.
Published: January 2015

The food-borne pathogen
Vibrio parahaemolyticus
has been reported as being present in New Zealand (NZ) seawaters, but there have been no reported outbreaks of food-borne infection from commercially grown NZ seafood. Our study determined the current incidence of
V. parahaemolyticus
in NZ oysters and Greenshell mussels and the prevalence of
V. parahaemolyticus
tdh
and
trh
strains. Pacific (235) and dredge (21) oyster samples and mussel samples (55) were obtained from commercial shellfish-growing areas between December 2009 and June 2012. Total
V. parahaemolyticus
numbers and the presence of pathogenic genes
tdh
and
trh
were determined using the FDA most-probable-number (MPN) method and confirmed using PCR analysis. In samples from the North Island of NZ,
V. parahaemolyticus
was detected in 81% of Pacific oysters and 34% of mussel samples, while the numbers of
V. parahaemolyticus
tdh
and
trh
strains were low, with just 3/215 Pacific oyster samples carrying the
tdh
gene.
V. parahaemolyticus
organisms carrying
tdh
and
trh
were not detected in South Island samples, and
V. parahaemolyticus
was detected in just 1/21 dredge oyster and 2/16 mussel samples. Numbers of
V. parahaemolyticus
organisms increased when seawater temperatures were high, the season when most commercial shellfish-growing areas are not harvested. The numbers of
V. parahaemolyticus
organisms in samples exceeded 1,000 MPN/g only when the seawater temperatures exceeded 19°C, so this environmental parameter could be used as a trigger warning of potential hazard. There is some evidence that the total
V. parahaemolyticus
numbers increased compared with those reported from a previous 1981 to 1984 study, but the analytical methods differed significantly.
Unexplained weight loss in an 80-year-old woman
Authors: Taylor Imogen Aleksandra , Gill Isaac , Harripaul Azad
Published: January 2015

An 80-year-old woman presented with long-standing history of weight loss and malnutrition, which had caused her to become reliant on the use of a wheelchair. Her symptoms were initially attributed to her medical comorbidities, however, during admission it became apparent that she had been suffering from depression and had gone on to develop an eating disorder. Eating disorders are most common in young adults but can affect all age groups, including the elderly population. The diagnosis is rarely considered in such patients and easily overlooked, especially when in the presence of chronic conditions and cognitive decline. A pre-existing psychiatric issue, most often depression, may also be present in this age group. There are no current treatment methods targeting patients in this population, who may not respond as effectively to the available strategies directed at young adults. It is important to always consider an eating disorder as a contributor or direct cause of unexplained weight loss in elderly patients.
Systemic inflammatory disease resolution following cosmetic silicone breast implant removal
Authors: Chan Sue Ann , Malik Feryal , Wharton Simon , Klocke Rainer
Published: January 2015

A 37-year-old Caucasian woman presented with subacute, symmetrical inflammatory arthralgia, which was affecting her work. Apart from fatigue, she had no other constitutional symptoms. She had undergone cosmetic bilateral silicone breast implant surgery in 2008. Blood tests revealed erythrocyte sedimentation rate 53 mm/h, weakly positive antinuclear antibodies and IgG cardiolipin antibody, while breast ultrasound revealed a ruptured left silicone implant. The working diagnosis was systemic inflammatory disease of uncertain origin. She decided to have replacement, rather than removal, of her silicone breast implants privately, but her symptoms persisted postoperatively with a new erythema multiforme-like rash despite treatment with methotrexate and moderate dose prednisolone. Following further consultation with a National Health Service breast surgeon, her silicone implants were removed. Within 10 weeks of surgery, all immunomodulatory treatment was discontinued with complete symptom and inflammatory response resolution. This case illustrates that implant silicone can induce clinically significant systemic inflammatory disease and implant removal is essential for disease resolution.
Page kidney due to a renal pseudocyst in a setting of pancreatitis
Authors: Aswani Yashant , Anandpara Karan Manoj , Hira Priya
Published: January 2015

Pancreatic pseudocysts are notorious for their extension beyond the normal confines of the pancreatic bed due to dissection of the enzymatic pseudocyst fluid along fascial planes. Such collections of pancreatic juice may compress the kidney. Extension of the pseudocyst into the perirenal space is, however, uncommon. We report a case of pseudocyst of pancreas lying in the subcapsular plane of the left kidney with a patent communication with the pancreatic duct (pancreaticorenal fistula). The compressive effect of the pseudocyst on the kidney compromised intrarenal perfusion as evidenced by a faint nephrogram but a normal renal artery. This led to renin–angiotensin–aldosterone mediated hypertension—the Page kidney phenomenon. Extensive literature search revealed our case to be the only one to describe such an occurrence.
ECG phasic voltage changes associated with spontaneous pneumothorax in a patient with vanishing lung syndrome
Authors: Fei Jeffrey , Marill Keith A
Published: January 2015

Alternating or phasic ECG voltage changes are most commonly associated with intrinsic myocardial electrophysiological perturbations or mechanical oscillation within a pericardial effusion. Rare descriptions of electrical alternation have been reported with pneumothorax. We present a case of a 53-year-old woman with vanishing lung syndrome who presented with spontaneous left pneumothorax and phasic ECG voltage changes that resolved after re-expansion of the lung.
Spinal cysticercosis: an unusual presentation
Authors: Chaurasia Rameshwar Nath , Mishra Vijay Nath , Jaiswal Shalini
Published: January 2015

Spinal intramedullary cysticercosis is an uncommon clinical condition that may mimic an intramedullary tumour and can lead to irreversible neurological deficits if untreated. We report a case of a 35-year-old man who clinically presented as Brown-Sequard syndrome, having thoracic cord cysticercosis at T11 level. MRI of the spine revealed a well-defined round intramedullary inflammatory lesion with scolex and perilesional oedema at D11 level.
Fatal endotracheal tube obstruction due to the ball valve effect
Authors: Woittiez Karen Jante , Woittiez Arend Jan Jacob
Published: January 2015

In patients suffering from pulmonary haemorrhage, or in patients who recently received a tracheostomy, acute occlusion of the endotracheal tube due to a blood clot is a rare, but well-known complication. Acute and complete occlusion of the tube is easily recognisable. There are various methods of removing the obstructive clot, such as using a bronchoscope with forceps, topical thrombolysis, saline lavage and suctioning. There are no guidelines concerning preventive routine bronchoscopic lavage. When there is a partial obstruction of the endotracheal tube, ventilation is possible, although high inspiratory pressures are necessary. If the clot functions as a ball valve ventil, raised intrathoracic pressure will cause right-sided heart failure or tension pneumothorax. It is important to recognise a partially obstructed tube in time and remove the obstruction.
Severe colic mimicking intussusception: a new phenomenon
Authors: El-Gohary Mohamed Amin
Published: January 2015

Objective

To highlight a new phenomenon that we have encountered in children during the past 5 years. Children in this group have a pathognomonic clinical picture of sudden acute severe abdominal colic during which the child is continuously screaming for 1–2 min. All these patients were initially diagnosed on clinical and ultrasonographic grounds as acute intussusception. Careful interpretation of the radiological findings revealed faecal impaction of the terminal ileum and caecum.

Design

This is a retrospective study looking at children presenting between 2009 and 2014 with acute severe abdominal colic pain. These were 11 patients aged 9 months to 5 years. We reviewed our experience in the management and diagnosis of these patients.

Result

All patients were diagnosed initially as intussusception, which was confirmed by ultrasonography (US). US revealed an appearance mimicking intussusception, 3 cases of which were intermittent. This US appearance proved to be a hard stool filling the terminal ileum. In all patients, abdominal X-ray revealed stool at the right side of the colon filling the caecum. Diagnostic gastrografin enemas that were performed in four patients excluded intussusception and confirmed stool at the caecum and ascending colon. In none of those patients had contrast passed into the terminal ileum. There was dramatic response to fleet and/or gastrografin enemas. Five patients required a second dose of enema and two patients required three doses.

Conclusions

We highlight a new phenomenon of severe abdominal pain caused by faecal impaction of the terminal ileum and caecum. Increased awareness of this condition helps to avoid unnecessary investigations and/or surgical exploration.
Demystifying theory and its use in improvement
Authors: Davidoff Frank , Dixon-Woods Mary , Leviton Laura , Michie Susan
Published: January 2015

The role and value of theory in improvement work in healthcare has been seriously underrecognised. We join others in proposing that more informed use of theory can strengthen improvement programmes and facilitate the evaluation of their effectiveness. Many professionals, including improvement practitioners, are unfortunately mystified—and alienated—by theory, which discourages them from using it in their work. In an effort to demystify theory we make the point in this paper that, far from being discretionary or superfluous, theory (‘reason-giving’), both informal and formal, is intimately woven into virtually all human endeavour. We explore the special characteristics of grand, mid-range and programme theory; consider the consequences of misusing theory or failing to use it; review the process of developing and applying programme theory; examine some emerging criteria of ‘good’ theory; and emphasise the value, as well as the challenge, of combining informal experience-based theory with formal, publicly developed theory. We conclude that although informal theory is always at work in improvement, practitioners are often not aware of it or do not make it explicit. The germane issue for improvement practitioners, therefore, is notwhether they usetheory butwhether they make explicitthe particular theory or theories, informal and formal, they actually use.
Inter-rater reliability of J-point location and measurement of the magnitude of ST segment elevation at the J-point on ECGs of STEMI patients by emergency department doctors
Authors: Lim Hoon Chin Steven , Salandanan Edgar Azada , Phillips Rachel , Tan Jun Guan , Hezan Muhammad Azmi
Published: January 2015

Introduction and objectives

Identification of the J-point and measurement of ST segment elevation at the J-point are important for the diagnosis of ST-elevation myocardial infarction (STEMI). We conducted a study to determine the inter-rater reliability (IRR) of J-point location and measurement of the magnitude of ST elevation at the J-point on ECGs of patients with STEMI by emergency department (ED) doctors.

Subjects and methods

Each participant examined 20 STEMI ECGs during a 1-month period in 2013. The participants were required to locate the J-point by selecting the small 1 mm square within which the J-point is located and measure the magnitude of ST elevation at the J-point identified (rounded up to the nearest 0.5 mm). The intraclass correlation coefficient (ICC) was calculated to assess the IRR.

Results

Thirty doctors participated. The ICC assessing the degree to which all participants provided agreement in their assessment of the location of J-points across ECGs was 0.85 (95% CI 0.75 to 0.93), which is in the excellent range. The ICC for assessing the magnitude of ST elevation was 0.97 (95% CI 0.94 to 0.98), indicating excellent agreement as well.

Conclusions

ED doctors show a high level of agreement when determining the location of J-points and measuring the magnitude of ST elevation at those J-points on ECGs of patients with STEMI. The findings support the measurement of ST segment elevation at the J-point in STEMI cases and should be regarded as a consistent standard to avoid confusion.
New and emerging endoscopic haemostasis techniques
Authors: Palmer Rebecca , Braden Barbara
Published: January 2015

Endoscopic treatment has been accepted as first-line treatment of upper gastrointestinal bleeding, both for variceal as well as for non-variceal haemorrhage. Dual modality treatment including injection therapy with mechanical or thermal haemostatic techniques has shown superior outcome compared with injection monotherapy in non-variceal bleeding. During recent years, new endoscopic devices have been developed and existing endoscopic techniques have been adapted to facilitate primary control of bleeding or achieve haemostasis in refractory haemorrhage. For mechanical haemostasis, larger, rotatable and repositionable clips have been developed; multiple-preloaded clips are also available now. Over the scope clips allow to ligate larger vessels and can close ulcer defects up to 20 mm. Topical, easily applied substances withdraw fluid from the blood and thereby initiate blood clotting. This can be helpful in diffuse oozing bleeding, for example, from tumour or hypertensive gastropathy and has also shown promising results in variceal and arterial bleeding as bridging before definitive treatment is available. Radiofrequency ablation and multiband ligation have emerged as new tools in the endoscopic management of gastric antral vascular ectasia. In acute refractory variceal bleeding, a covered and removable oesophagus stent can provide tamponade and gain time for transport to an interventional endoscopic centre or for radiological intervention such as TIPS.