bluuebunny/crossref_metadata_2025 huggingface dataset:
Using attachment theory to inform the design and delivery of mental health services: A systematic review of the literature
Authors: Bucci Sandra , Roberts Nicola H. , Danquah Adam N. , Berry Katherine
Published: April 2014

Purpose

The aim of this review was to propose and describe the design and delivery of an attachment‐informed general mental health service.

Method

We systematically searched the PsycINFO, MEDLINE, Web of Knowledge, COPAC, CINAHL, and Science Direct databases from 1960 to 2013. We also searched reference lists of relevant papers and directly contacted authors in the field. Literature describing attachment theory and its applicability in designing and delivering general mental health services was synthesized using thematic analysis. Papers published in English, books or chapters in edited books that described applying attachment theory in designing and delivering mental health services for adults and adolescents were included in the review. Of the 1,105 articles identified, 14 met inclusion criteria for the review. Eight key themes, and four subthemes, were extracted and organized to reflect the experience of a service user moving through the mental health system.

Results

Key themes extracted were as follows: service policy and evaluation; referrals; assessment and formulation; intervention; support for staff; support for carers; moving on; and potential service benefits. Papers reviewed suggested that service users with severe mental health problems have attachment needs that should be met in general mental health services.

Conclusions

Attachment theory provides a useful framework to inform the design and delivery of general mental health services. The resource implications for services are discussed, as are limitations of the review and recommendations for future research.

Practitioner points

Attachment theory should be used to inform the design and delivery of general mental health services.

Mental health services should evaluate the extent to which they meet service users' attachment needs.

Attachment‐informed mental health services should assess outcomes, including cost‐effectiveness over time.

Papers included in this review focus on long‐stay residential care or secure services and there is a limited experimental evidence base to show that providing an attachment‐informed service improves patient outcomes.
Significance of new lung infiltrates in outpatients after lung and heart–lung transplantation
Authors: Díaz‐Ravetllat V. , Greer M. , Haverich A. , Warnecke G. , Dierich M. , Welte T. , Gottlieb J.
Published: April 2014

Background

Infection and rejection represent major complications following lung transplantation and are often associated with pulmonary infiltrates. The differential diagnosis of these infiltrates depends on their timing after transplantation. The aim of this study was to characterize lung transplant recipients (LTR) presenting with new pulmonary infiltrates.

Methods

A retrospective analysis of all LTR and heart–lung transplant recipients attending outpatient follow‐up at our institution between September 1, 2006 and October 14, 2011 was performed. All patients presenting with new pulmonary infiltrates on chest x‐ray who underwent bronchoscopy were included.

Results

A total of 913 patients accounted for 13,156 attendances, with 3,912 bronchoscopies being performed. Seventy‐eight patients (9%) exhibited new pulmonary infiltrates and proceeded to bronchoscopy. Infiltrates occurred at a median 15 (interquartile range [IQR] 5–39) months after transplantation. Forty‐eight patients (62%) were male, and median patient age was 47 (IQR 29–57) years. Subsequent investigation revealed pneumonia to be the underlying cause in 63 patients (81%). In the remaining patients, chronic lung allograft dysfunction (CLAD) was responsible in 6 (8%), acute rejection in 5 (6%), and toxic pneumonitis in 4 (5%) patients. Overall 1‐year survival in LTR presenting with new infiltrates was 97%, compared with 96% for all LTR attending our Outpatient Department.

Conclusions

New pulmonary infiltrates occurring after the first month in LTR are most likely due to infection. Through prompt diagnosis and treatment, early mortality appears unaffected. Late mortality remains attributable to CLAD.
The Arabidopsis STRESS RESPONSE SUPPRESSOR DEAD‐box RNA helicases are nucleolar‐ and chromocenter‐localized proteins that undergo stress‐mediated relocalization and are involved in epigenetic gene silencing
Authors: Khan Asif , Garbelli Anna , Grossi Serena , Florentin Assa , Batelli Giorgia , Acuna Tania , Zolla Gaston , Kaye Yuval , Paul Laju K. , Zhu Jian‐Kang , Maga Giovanni , Grafi Gideon , Barak Simon
Published: April 2014

DEAD‐box RNA helicases are involved in many aspects of RNA metabolism and in diverse biological processes in plants. Arabidopsis thaliana mutants of two DEAD‐box RNA helicases, STRESS RESPONSE SUPPRESSOR1 (STRS1) and STRS2 were previously shown to exhibit tolerance to abiotic stresses and up‐regulated stress‐responsive gene expression. Here, we show that Arabidopsis STRS‐overexpressing lines displayed a less tolerant phenotype and reduced expression of stress‐induced genes confirming the STRSs as attenuators of Arabidopsis stress responses. GFP–STRS fusion proteins exhibited localization to the nucleolus, nucleoplasm and chromocenters and exhibited relocalization in response to abscisic acid (ABA) treatment and various stresses. This relocalization was reversed when stress treatments were removed. The STRS proteins displayed mis‐localization in specific gene‐silencing mutants and exhibited RNA‐dependent ATPase and RNA‐unwinding activities. In particular, STRS2 showed mis‐localization in three out of four mutants of the RNA‐directed DNA methylation (RdDM) pathway while STRS1 was mis‐localized in the hd2c mutant that is defective in histone deacetylase activity. Furthermore, heterochromatic RdDM target loci displayed reduced DNA methylation and increased expression in the strs mutants. Taken together, our findings suggest that the STRS proteins are involved in epigenetic silencing of gene expression to bring about suppression of the Arabidopsis stress response.
Exercise performance is regulated during repeated sprints to limit the development of peripheral fatigue beyond a critical threshold
Authors: Hureau Thomas J. , Olivier Nicolas , Millet Guillaume Y. , Meste Olivier , Blain Gregory M.
Published: April 2014

New Findings

What is the central question of this study?

We asked whether exercise performance is regulated during all‐out repeated sprints (involving peak cycling‐specific muscle activation and limited pacing strategy) in order to restrain the total degree of peripheral fatigue development.

What is the main finding and its importance?

Our results showed that power output is adjusted during repeated sprints to limit the development of peripheral fatigue to a critical threshold, independently of the degree of pre‐existing fatigue. These findings emphasize the important role of peripheral fatigue in adjustment of power output during exercise.

We hypothesized that exercise performance is adjusted during repeated sprints in order not to surpass a critical threshold of peripheral fatigue. Twelve men randomly performed three experimental sessions on different days, i.e. one single 10 s all‐out sprint and two trials of 10 × 10 s all‐out sprints with 30 s of passive recovery in between. One trial was performed in the unfatigued state (CTRL) and one following electrically induced quadriceps muscle fatigue (FTNMES). Peripheral fatigue was quantified by comparing pre‐ with postexercise changes in potentiated quadriceps twitch force (ΔQtw‐pot) evoked by supramaximal magnetic stimulation of the femoral nerve. Central fatigue was estimated by comparing pre‐ with postexercise voluntary activation of quadriceps motor units. The root mean square (RMS) of the vastus lateralis and vastus medialis EMG normalized to maximal M‐wave amplitude (RMS.Mmax−1) was also calculated during sprints. Compared with CTRL condition, pre‐existing quadriceps muscle fatigue in FTNMES (ΔQtw‐pot = −29 ± 4%) resulted in a significant (P < 0.05) reduction in power output (−4.0 ± 0.9%) associated with a reduction in RMS.Mmax−1. However, ΔQtw‐pot postsprints decreased by 51% in both conditions, indicating that the level of peripheral fatigue was identical and independent of the degree of pre‐existing fatigue. Our findings show that power output and cycling EMG are adjusted during exercise in order to limit the development of peripheral fatigue beyond a constant threshold. We hypothesize that the contribution of peripheral fatigue to exercise limitation involves a reduction in central motor drive in addition to the impairment in muscular function.
Calibration of tip and sample temperature of a scanning tunneling microscope using a superconductive sample
Authors: Stocker Matthias , Pfeifer Holger , Koslowski Berndt
Published: April 2014

The temperature of the electrodes is a crucial parameter in virtually all tunneling experiments. The temperature not only controls the thermodynamic state of the electrodes but also causes thermal broadening, which limits the energy resolution. Unfortunately, the construction of many scanning tunneling microscopes inherits a weak thermal link between tip and sample in order to make one side movable. Such, the temperature of that electrode is badly defined. Here, the authors present a procedure to calibrate the tip temperature by very simple means. The authors use a superconducting sample (Nb) and a standard tip made from W. Due to the asymmetry in the density of states of the superconductor (SC)—normal metal (NM) tunneling junction, the SC temperature controls predominantly the density of states while the NM controls the thermal smearing. By numerically simulating the I-V curves and numerically optimizing the tip temperature and the SC gap width, the tip temperature can be accurately deduced if the sample temperature is known or measureable. In our case, the temperature dependence of the SC gap may serve as a temperature sensor, leading to an accurate NM temperature even if the SC temperature is unknown.
Bloch-wave expansion technique for predicting wave reflection and transmission in two-dimensional phononic crystals
Authors: Kulpe Jason A. , Sabra Karim G. , Leamy Michael J.
Published: April 2014

In this paper acoustic wave reflection and transmission are studied at the interface between a phononic crystal (PC) and a homogeneous medium using a Bloch wave expansion technique. A finite element analysis of the PC yields the requisite dispersion relationships and a complete set of Bloch waves, which in turn are employed to expand the transmitted pressure field. A solution for the reflected and transmitted wave fields is then obtained using continuity conditions at the half-space interface. The method introduces a group velocity criterion for Bloch wave selection, which when not enforced, is shown to yield non-physical results. Following development, the approach is applied to example PCs and results are compared to detailed numerical solutions, yielding very good agreement. The approach is also employed to uncover bands of incidence angles whereby perfect acoustic reflection from the PC occurs, even for frequencies outside of stop bands.
Performance of active feedforward control systems in non-ideal, synthesized diffuse sound fields
Authors: Misol Malte , Bloch Christian , Monner Hans Peter , Sinapius Michael
Published: April 2014

The acoustic performance of passive or active panel structures is usually tested in sound transmission loss facilities. A reverberant sending room, equipped with one or a number of independent sound sources, is used to generate a diffuse sound field excitation which acts as a disturbance source on the structure under investigation. The spatial correlation and coherence of such a synthesized non-ideal diffuse-sound-field excitation, however, might deviate significantly from the ideal case. This has consequences for the operation of an active feedforward control system which heavily relies on the acquisition of coherent disturbance source information. This work, therefore, evaluates the spatial correlation and coherence of ideal and non-ideal diffuse sound fields and considers the implications on the performance of a feedforward control system. The system under consideration is an aircraft-typical double panel system, equipped with an active sidewall panel (lining), which is realized in a transmission loss facility. Experimental results for different numbers of sound sources in the reverberation room are compared to simulation results of a comparable generic double panel system excited by an ideal diffuse sound field. It is shown that the number of statistically independent noise sources acting on the primary structure of the double panel system depends not only on the type of diffuse sound field but also on the sample lengths of the processed signals. The experimental results show that the number of reference sensors required for a defined control performance exhibits an inverse relationship to control filter length.
Consonant identification using temporal fine structure and recovered envelope cues
Authors: Swaminathan Jayaganesh , Reed Charlotte M. , Desloge Joseph G. , Braida Louis D. , Delhorne Lorraine A.
Published: April 2014

The contribution of recovered envelopes (RENVs) to the utilization of temporal-fine structure (TFS) speech cues was examined in normal-hearing listeners. Consonant identification experiments used speech stimuli processed to present TFS or RENV cues. Experiment 1 examined the effects of exposure and presentation order using 16-band TFS speech and 40-band RENV speech recovered from 16-band TFS speech. Prior exposure to TFS speech aided in the reception of RENV speech. Performance on the two conditions was similar (∼50%-correct) for experienced listeners as was the pattern of consonant confusions. Experiment 2 examined the effect of varying the number of RENV bands recovered from 16-band TFS speech. Mean identification scores decreased as the number of RENV bands decreased from 40 to 8 and were only slightly above chance levels for 16 and 8 bands. Experiment 3 examined the effect of varying the number of bands in the TFS speech from which 40-band RENV speech was constructed. Performance fell from 85%- to 31%-correct as the number of TFS bands increased from 1 to 32. Overall, these results suggest that the interpretation of previous studies that have used TFS speech may have been confounded with the presence of RENVs.
The origins of ambient biological sound from coral reef ecosystems in the Line Islands archipelago
Authors: Freeman Simon E. , Rohwer Forest L. , D'Spain Gerald L. , Friedlander Alan M. , Gregg Allison K. , Sandin Stuart A. , Buckingham Michael J.
Published: April 2014

Although ambient biological underwater sound was first characterized more than 60 years ago, attributing specific components of ambient sound to their creators remains a challenge. Noise produced by snapping shrimp typically dominates the ambient spectra near tropical coasts, but significant unexplained spectral variation exists. Here, evidence is presented indicating that a discernible contribution to the ambient sound field over coral reef ecosystems in the Line Islands archipelago originates from the interaction of hard-shelled benthic macro-organisms with the coral substrate. Recordings show a broad spectral peak centered between 14.30 and 14.63 kHz, incoherently added to a noise floor typically associated with relatively “white” snapping shrimp sounds. A 4.6 to 6.2 dB increase of pressure spectral density level in the 11 to 17 kHz band occurs simultaneously with an increase in benthic invertebrate activity at night, quantified through time-lapse underwater photography. Spectral-level-filtered recordings of hermit crabs Clibanarius diugeti in quiet aquarium conditions reveal that transient sounds produced by the interaction between the crustaceans' carapace, shell, and coral substrate are spectrally consistent with Line Islands recordings. Coral reef ecosystems are highly interconnected and subtle yet important ecological changes may be detected quantitatively through passive monitoring that utilizes the acoustic byproducts of biological activity.
A viscoelastic laryngeal muscle model with active components
Authors: Smith Simeon L. , Hunter Eric J.
Published: April 2014

Accurate definitions of both passive and active tissue characteristics are important to laryngeal muscle modeling. This report tested the efficacy of a muscle model which added active stress components to an accurate definition of passive properties. Using the previously developed three-network Ogden model to simulate passive stress, a Hill-based contractile element stress equation was utilized for active stress calculations. Model input parameters were selected based on literature data for the canine cricothyroid muscle, and simulations were performed in order to compare the model behavior to published results for the same muscle. The model results showed good agreement with muscle behavior, including appropriate tetanus response and contraction time for isometric conditions, as well as accurate stress predictions in response to dynamic strain with activation.
Effect of boundary diffusers in a reverberation chamber: Standardized diffuse field quantifiers
Authors: Bradley David T. , Müller-Trapet Markus , Adelgren Jacob , Vorländer Michael
Published: April 2014

The sound field inside a reverberation chamber must have a high degree of diffusivity to allow for the accurate measurement of various acoustic quantities. Typically, hanging or rotating diffuser panels are installed in the chamber in an effort to achieve this diffusivity. However, both of these diffuser types have certain limitations, and adequate sound field diffusivity is often difficult to realize. A 1:5 scale reverberation chamber has been used to systematically analyze the relative effectiveness of hanging diffusers versus an alternative diffuser type referred to as a boundary diffuser. To characterize sound field diffusivity, three quantifiers from the ASTM E90, ASTM C423, and ISO 354 standards have been used: maximum absorption coefficient, standard deviation of decay rate, and total confidence interval. Analysis of the quantifier data reveals that boundary diffusers and hanging diffusers produce roughly equivalent diffusion in the sound field. The data also show that the standards have certain inconsistencies that can obfuscate the characterization of sound field diffusivity, which may explain reproducibility and repeatability issues previously documented in the literature.
Attenuation of standing waves in a large water tank using arrays of large tethered encapsulated bubbles
Authors: Lee Kevin M. , Wilson Preston S. , Wochner Mark S.
Published: April 2014

The use of bubble resonance effects to attenuate low-frequency underwater sound was investigated experimentally in a large water tank. A compact electromechanical sound source was used to excite standing wave fields at frequencies ranging between 50 and 200 Hz in the tank. The source was then surrounded by a stationary array of tethered encapsulated air bubbles, and reduction in standing wave amplitude by as much as 26 dB was observed. The bubbles consisted of either thin-shelled latex balloons with approximately 5 cm radii or thicker-shelled vinyl boat fenders with 6.9 cm radii. The effects of changing the material and thickness of the bubble shells were found to be in qualitative agreement with predictions from Church's model for sound propagation in a liquid containing encapsulated bubbles [J. Acoust. Soc. Am. 97, 1510–1521 (1995)]. Although demonstrated here for low frequency noise abatement within a tank, which is useful for quieting acoustic test facilities and large tanks used for marine life husbandry, the eventual aim of this work is to use stationary arrays of large tethered encapsulated bubbles to abate low frequency underwater noise from anthropogenic sources in the marine environment.
Closed-cell crystalline foams: Self-assembling, resonant metamaterials
Authors: Spadoni Alessandro , Höhler Reinhard , Cohen-Addad Sylvie , Dorodnitsyn Vladimir
Published: April 2014

Internal degrees of freedom and periodic structure are critical requirements in the design of acoustic/elastic metamaterials since they can give rise to extraordinary properties like negative effective mass and stiffness. However, they are challenging to realize in three dimensions. Closed-cell, crystalline foams are a particularly advantageous basis to develop metamaterials as they intrinsically have a complex microstructure, exhibiting internal resonances. Recently self-assembly techniques have been implemented to produce such foams: a Kelvin (body centered cubic) foam, a face centered cubic foam, and a Weaire-Phelan structure. Numerical models are employed to demonstrate that such foams are superanisotropic, selectively behaving as a fluid or a solid, pentamode solids as a result of fluid–structure interaction, in addition to having regimes characterized by film resonances and high density of states. Microstructural deformations obtained from numerical models allow the derivation of equivalent mechanical models.
Bi-stable vocal fold adduction: A mechanism of modal-falsetto register shifts and mixed registration
Authors: Titze Ingo R.
Published: April 2014

The origin of vocal registers has generally been attributed to differential activation of cricothyroid and thyroarytenoid muscles in the larynx. Register shifts, however, have also been shown to be affected by glottal pressures exerted on vocal fold surfaces, which can change with loudness, pitch, and vowel. Here it is shown computationally and with empirical data that intraglottal pressures can change abruptly when glottal adductory geometry is changed relatively smoothly from convergent to divergent. An intermediate shape between large convergence and large divergence, namely, a nearly rectangular glottal shape with almost parallel vocal fold surfaces, is associated with mixed registration. It can be less stable than either of the highly angular shapes unless transglottal pressure is reduced and upper stiffness of vocal fold tissues is balanced with lower stiffness. This intermediate state of adduction is desirable because it leads to a low phonation threshold pressure with moderate vocal fold collision. Achieving mixed registration consistently across wide ranges of F0, lung pressure, and vocal tract shapes appears to be a balancing act of coordinating laryngeal muscle activation with vocal tract pressures. Surprisingly, a large transglottal pressure is not facilitative in this process, exacerbating the bi-stable condition and the associated register contrast.
Dynamic characterization of viscoelastic porous foams used in vehicles based on an inverse finite element method
Authors: Finnveden Svante , Hörlin Nils-Erik , Barbagallo Mathias
Published: April 2014

Viscoelastic properties of porous materials, typical of those used in vehicles for noise insulation and absorption, are estimated from measurements and inverse finite element procedures. The measurements are taken in a near vacuum and cover a broad frequency range: 20 Hz to 1 kHz. The almost cubic test samples were made of 25 mm foam covered by a “heavy layer” of rubber. They were mounted in a vacuum chamber on an aluminum table, which was excited in the vertical and horizontal directions with a shaker. Three kinds of response are measured allowing complete estimates of the viscoelastic moduli for isotropic materials and also providing some information on the degree of material anisotropicity. First, frequency independent properties are estimated, where dissipation is described by constant loss factors. Then, fractional derivative models that capture the variation with frequency of the stiffness and damping are adapted. The measurement setup is essentially two-dimensional and calculations are three-dimensional and for a state of plane strain. The good agreement between measured and calculated response provides some confidence in the presented procedures. If, however, the material model cannot fit the measurements well, the inverse procedure yields a certain degree of arbitrariness to the parameter estimation.
Accommodating to new ears: The effects of sensory and sensory-motor feedback
Authors: Carlile Simon , Balachandar Kapilesh , Kelly Heather
Published: April 2014

Changing the shape of the outer ear using small in-ear molds degrades sound localization performance consistent with the distortion of monaural spectral cues to location. It has been shown recently that adult listeners re-calibrate to these new spectral cues for locations both inside and outside the visual field. This raises the question as to the teacher signal for this remarkable functional plasticity. Furthermore, large individual differences in the extent and rate of accommodation suggests a number of factors may be driving this process. A training paradigm exploiting multi-modal and sensory-motor feedback during accommodation was examined to determine whether it might accelerate this process. So as to standardize the modification of the spectral cues, molds filling 40% of the volume of each outer ear were custom made for each subject. Daily training sessions for about an hour, involving repetitive auditory stimuli and exploratory behavior by the subject, significantly improved the extent of accommodation measured by both front-back confusions and polar angle localization errors, with some improvement in the rate of accommodation demonstrated by front-back confusion errors. This work has implications for both the process by which a coherent representation of auditory space is maintained and for accommodative training for hearing aid wearers.
Cartilage conduction hearing
Authors: Shimokura Ryota , Hosoi Hiroshi , Nishimura Tadashi , Yamanaka Toshiaki , Levitt Harry
Published: April 2014

Sound information is known to travel to the cochlea via either air or bone conduction. However, a vibration signal, delivered to the aural cartilage via a transducer, can also produce a clearly audible sound. This type of conduction has been termed “cartilage conduction.” The aural cartilage forms the outer ear and is distributed around the exterior half of the external auditory canal. In cartilage conduction, the cartilage and transducer play the roles of a diaphragm and voice coil of a loudspeaker, respectively. There is a large gap between the impedances of cartilage and skull bone, such that cartilage vibrations are not easily transmitted through bone. Thus, these methods of conduction are distinct. In this study, force was used to apply a transducer to aural cartilage, and it was found that the sound in the auditory canal was amplified, especially for frequencies below 2 kHz. This effect was most pronounced at an application force of 1 N, which is low enough to ensure comfort in the design of hearing aids. The possibility of using force adjustments to vary amplification may also have applications for cell phone design.
Producing undistorted acoustic sine waves
Authors: Boutin Henri , Smith John , Wolfe Joe
Published: April 2014

A simple digital method is described that can produce an undistorted acoustic sine wave using an amplifier and loudspeaker having considerable intrinsic distortion, a common situation at low frequencies and high power. The method involves, first, using a pure sine wave as the input and measuring the distortion products. An iterative procedure then progressively adds harmonics with appropriate amplitude and phase to cancel any distortion products. The method is illustrated by producing a pure 52 Hz sine wave at 107 dB sound pressure level with harmonic distortion reduced over the audible range to >65 dB below the fundamental.
Two dimensional sound field reproduction using higher order sources to exploit room reflections
Authors: Betlehem Terence , Poletti Mark A.
Published: April 2014

In this paper, sound field reproduction is performed in a reverberant room using higher order sources (HOSs) and a calibrating microphone array. Previously a sound field was reproduced with fixed directivity sources and the reverberation compensated for using digital filters. However by virtue of their directive properties, HOSs may be driven to not only avoid the creation of excess reverberation but also to use room reflection to contribute constructively to the desired sound field. The manner by which the loudspeakers steer the sound around the room is determined by measuring the acoustic transfer functions. The requirements on the number and order N of HOSs for accurate reproduction in a reverberant room are derived, showing a 2N + 1-fold decrease in the number of loudspeakers in comparison to using monopole sources. HOSs are shown applicable to rooms with a rich variety of wall reflections while in an anechoic room their advantages may be lost. Performance is investigated in a room using extensions of both the diffuse field model and a more rigorous image-source simulation method, which account for the properties of the HOSs. The robustness of the proposed method is validated by introducing measurement errors.
Characterization of the spatio-temporal response of optical fiber sensors to incident spherical waves
Authors: Veres István A. , Burgholzer Peter , Berer Thomas , Rosenthal Amir , Wissmeyer Georg , Ntziachristos Vasilis
Published: April 2014

In this study a theoretical framework for calculating the acoustic response of optical fiber-based ultrasound sensors is presented. The acoustic response is evaluated for optical fibers with several layers of coating assuming a harmonic point source with arbitrary position and frequency. First, the fiber is acoustically modeled by a layered cylinder on which spherical waves are impinged. The scattering of the acoustic waves is calculated analytically and used to find the normal components of the strains on the fiber axis. Then, a strain-optic model is used to calculate the phase shift experienced by the guided mode in the fiber owing to the induced strains. The framework is showcased for a silica fiber with two layers of coating for frequencies in the megahertz regime, commonly used in medical imaging applications. The theoretical results are compared to experimental data obtained with a sensing element based on a pi-phase-shifted fiber Bragg grating and with photoacoustically generated ultrasonic signals.
Experimental study on acoustic subwavelength imaging of holey-structured metamaterials by resonant tunneling
Authors: Su Haijing , Zhou Xiaoming , Xu Xianchen , Hu Gengkai
Published: April 2014

A holey-structured metamaterial is proposed for near-field acoustic imaging beyond the diffraction limit. The structured lens consists of a rigid slab perforated with an array of cylindrical holes with periodically modulated diameters. Based on the effective medium approach, the structured lens is characterized by multilayered metamaterials with anisotropic dynamic mass, and an analytic model is proposed to evaluate the transmission properties of incident evanescent waves. The condition is derived for the resonant tunneling, by which evanescent waves can completely transmit through the structured lens without decaying. As an advantage of the proposed lens, the imaging frequency can be modified by the diameter modulation of internal holes without the change of the lens thickness in contrast to the lens due to the Fabry–Pérot resonant mechanism. In this experiment, the lens is assembled by aluminum plates drilled with cylindrical holes. The imaging experiment demonstrates that the designed lens can clearly distinguish two sources separated in the distance below the diffraction limit at the tunneling frequency.
A quasianalytical time domain solution for scattering from a homogeneous sphere
Authors: Li Jie , Dault Daniel , Shanker Balasubramaniam
Published: April 2014

A transient spherical multipole expansion-like solution for acoustic scattering from a spherical object is derived within a mesh-free and singularity-free time domain integral equation (TDIE) framework for the sound-soft, sound-rigid and penetrable cases. The method is based on an expansion of the time domain Green's function that allows independent evaluation of spatial and temporal convolutions. The TDIE system is solved by descretizing the integral equations in space and time, forming a matrix system via the method of moments, and solving the system with the marching on in time algorithm. Spatial discretization using tesseral harmonics leads to closed form expressions for spatial integrals, and use of a strictly band limited temporal interpolant permits efficient, accurate computation of temporal convolutions via numerical quadrature. The accuracy of these integrations ensures late time stability and accuracy of the deconvolution data. Results presented demonstrate the accuracy and convergence of the approach for broadband simulations compared with Fourier transformed analytical data.
Correlating Microbial Diversity Patterns with Geochemistry in an Extreme and Heterogeneous Environment of Mine Tailings
Authors: Liu Jun , Hua Zheng-Shuang , Chen Lin-Xing , Kuang Jia-Liang , Li Sheng-Jin , Shu Wen-Sheng , Huang Li-Nan
Published: April 2014

Recent molecular surveys have advanced our understanding of the forces shaping the large-scale ecological distribution of microbes in Earth's extreme habitats, such as hot springs and acid mine drainage. However, few investigations have attempted dense spatial analyses of specific sites to resolve the local diversity of these extraordinary organisms and how communities are shaped by the harsh environmental conditions found there. We have applied a 16S rRNA gene-targeted 454 pyrosequencing approach to explore the phylogenetic differentiation among 90 microbial communities from a massive copper tailing impoundment generating acidic drainage and coupled these variations in community composition with geochemical parameters to reveal ecological interactions in this extreme environment. Our data showed that the overall microbial diversity estimates and relative abundances of most of the dominant lineages were significantly correlated with pH, with the simplest assemblages occurring under extremely acidic conditions and more diverse assemblages associated with neutral pHs. The consistent shifts in community composition along the pH gradient indicated that different taxa were involved in the different acidification stages of the mine tailings. Moreover, the effect of pH in shaping phylogenetic structure within specific lineages was also clearly evident, although the phylogenetic differentiations within the
Alphaproteobacteria
,
Deltaproteobacteria
, and
Firmicutes
were attributed to variations in ferric and ferrous iron concentrations. Application of the microbial assemblage prediction model further supported pH as the major factor driving community structure and demonstrated that several of the major lineages are readily predictable. Together, these results suggest that pH is primarily responsible for structuring whole communities in the extreme and heterogeneous mine tailings, although the diverse microbial taxa may respond differently to various environmental conditions.
Impact of UV and Peracetic Acid Disinfection on the Prevalence of Virulence and Antimicrobial Resistance Genes in Uropathogenic Escherichia coli in Wastewater Effluents
Authors: Biswal Basanta Kumar , Khairallah Ramzi , Bibi Kareem , Mazza Alberto , Gehr Ronald , Masson Luke , Frigon Dominic
Published: April 2014

Wastewater discharges may increase the populations of pathogens, including
Escherichia coli
, and of antimicrobial-resistant strains in receiving waters. This study investigated the impact of UV and peracetic acid (PAA) disinfection on the prevalence of virulence and antimicrobial resistance genes in uropathogenic
Escherichia coli
(UPEC), the most abundant
E. coli
pathotype in municipal wastewaters. Laboratory disinfection experiments were conducted on wastewater treated by physicochemical, activated sludge, or biofiltration processes; 1,766
E. coli
isolates were obtained for the evaluation. The target disinfection level was 200 CFU/100 ml, resulting in UV and PAA doses of 7 to 30 mJ/cm
2
and 0.9 to 2.0 mg/liter, respectively. The proportions of UPECs were reduced in all samples after disinfection, with an average reduction by UV of 55% (range, 22% to 80%) and by PAA of 52% (range, 11% to 100%). Analysis of urovirulence genes revealed that the decline in the UPEC populations was not associated with any particular virulence factor. A positive association was found between the occurrence of urovirulence and antimicrobial resistance genes (ARGs). However, the changes in the prevalence of ARGs in potential UPECs were different following disinfection, i.e., UV appears to have had no effect, while PAA significantly reduced the ARG levels. Thus, this study showed that both UV and PAA disinfections reduced the proportion of UPECs and that PAA disinfection also reduced the proportion of antimicrobial resistance gene-carrying UPEC pathotypes in municipal wastewaters.
Evolved Osmotolerant Escherichia coli Mutants Frequently Exhibit Defective
N
-Acetylglucosamine Catabolism and Point Mutations in Cell Shape-Regulating Protein MreB
Authors: Winkler James D. , Garcia Carlos , Olson Michelle , Callaway Emily , Kao Katy C.
Published: April 2014

Biocatalyst robustness toward stresses imposed during fermentation is important for efficient bio-based production. Osmotic stress, imposed by high osmolyte concentrations or dense populations, can significantly impact growth and productivity. In order to better understand the osmotic stress tolerance phenotype, we evolved sexual (capable of
in situ
DNA exchange) and asexual
Escherichia coli
strains under sodium chloride (NaCl) stress. All isolates had significantly improved growth under selection and could grow in up to 0.80 M (47 g/liter) NaCl, a concentration that completely inhibits the growth of the unevolved parental strains. Whole genome resequencing revealed frequent mutations in genes controlling
N
-acetylglucosamine catabolism (
nagC
,
nagA
), cell shape (
mrdA
,
mreB
), osmoprotectant uptake (
proV
), and motility (
fimA
). Possible epistatic interactions between
nagC
,
nagA
,
fimA
, and
proV
deletions were also detected when reconstructed as defined mutations. Biofilm formation under osmotic stress was found to be decreased in most mutant isolates, coupled with perturbations in indole secretion. Transcriptional analysis also revealed significant changes in
ompACGL
porin expression and increased transcription of sulfonate uptake systems in the evolved mutants. These findings expand our current knowledge of the osmotic stress phenotype and will be useful for the rational engineering of osmotic tolerance into industrial strains in the future.
hypD
as a Marker for [NiFe]-Hydrogenases in Microbial Communities of Surface Waters
Authors: Beimgraben Christian , Gutekunst Kirstin , Opitz Friederike , Appel Jens
Published: April 2014

Hydrogen is an important trace gas in the atmosphere. Soil microorganisms are known to be an important part of the biogeochemical H
2
cycle, contributing 80 to 90% of the annual hydrogen uptake. Different aquatic ecosystems act as either sources or sinks of hydrogen, but the contribution of their microbial communities is unknown. [NiFe]-hydrogenases are the best candidates for hydrogen turnover in these environments since they are able to cope with oxygen. As they lack sufficiently conserved sequence motifs, reliable markers for these enzymes are missing, and consequently, little is known about their environmental distribution. We analyzed the essential maturation genes of [NiFe]-hydrogenases, including their frequency of horizontal gene transfer, and found
hypD
to be an applicable marker for the detection of the different known hydrogenase groups. Investigation of two freshwater lakes showed that [NiFe]-hydrogenases occur in many prokaryotic orders. We found that the respective
hypD
genes cooccur with oxygen-tolerant [NiFe]-hydrogenases (groups 1 and 5) mainly of
Actinobacteria
,
Acidobacteria
, and
Burkholderiales
; cyanobacterial uptake hydrogenases (group 2a) of cyanobacteria; H
2
-sensing hydrogenases (group 2b) of
Burkholderiales
,
Rhizobiales
, and
Rhodobacterales
; and two groups of multimeric soluble hydrogenases (groups 3b and 3d) of
Legionellales
and cyanobacteria. These findings support and expand a previous analysis of metagenomic data (M. Barz et al., PLoS One 5:e13846, 2010,
http://dx.doi.org/10.1371/journal.pone.0013846
) and further identify [NiFe]-hydrogenases that could be involved in hydrogen cycling in aquatic surface waters.
High Prevalence of Enterocytozoon bieneusi in Asymptomatic Pigs and Assessment of Zoonotic Risk at the Genotype Level
Authors: Zhao Wei , Zhang Weizhe , Yang Fengkun , Cao Jianping , Liu Hua , Yang Dong , Shen Yujuan , Liu Aiqin
Published: April 2014

Enterocytozoon bieneusi
is an emerging and clinically significant enteric parasite infecting humans and animals and can cause life-threatening diarrhea in immunocompromised people. Pigs are considered to be one of the main reservoir hosts of
E. bieneusi
based on their high prevalence rates and zoonotic genotypes in pigs. As an opportunistic pathogen,
E. bieneusi
infection of pigs can be inapparent, which leads to neglect in detecting this parasite in pigs and assessing the epidemiological role of pigs in the transmission of human microsporidiosis. In the present study, 95 healthy pigs aged 2 or 3 months were randomly selected from three areas in Heilongjiang Province, China.
E. bieneusi
isolates were identified and genotyped based on the small-subunit (SSU) rRNA and internal transcribed spacer (ITS) regions of the rRNA gene by PCR and sequencing. A high prevalence of
E. bieneusi
was observed, 83.2% (79/95) at the SSU rRNA locus versus 89.5% (85/95) at the ITS locus. Ten ITS genotypes were obtained, comprising six known genotypes—EbpA (
n
= 30), D (
n
= 19), H (
n
= 18), O (
n
= 11), CS-1 (
n
= 1), and LW1 (
n
= 1)—and four novel genotypes named HLJ-I to HLJ-IV; 70.6% (60/85) of
E. bieneusi
genotypes were zoonotic (genotypes EbpA, D, and O). The findings of a high prevalence of
E. bieneusi
in pigs and a large percentage of zoonotic genotypes indicate that pigs may play a role in the transmission of
E. bieneusi
to humans and may become an important source of water contamination in our investigated areas.
Verrucomicrobia Are Candidates for Polysaccharide-Degrading Bacterioplankton in an Arctic Fjord of Svalbard
Authors: Cardman Z. , Arnosti C. , Durbin A. , Ziervogel K. , Cox C. , Steen A. D. , Teske A.
Published: April 2014

In Arctic marine bacterial communities, members of the phylumVerrucomicrobiaare consistently detected, although not typically abundant, in 16S rRNA gene clone libraries and pyrotag surveys of the marine water column and in sediments. In an Arctic fjord (Smeerenburgfjord) of Svalbard, members of theVerrucomicrobia, together withFlavobacteriaand smaller proportions ofAlpha- andGammaproteobacteria, constituted the most frequently detected bacterioplankton community members in 16S rRNA gene-based clone library analyses of the water column. Parallel measurements in the water column of the activities of six endo-acting polysaccharide hydrolases showed that chondroitin sulfate, laminarin, and xylan hydrolysis accounted for most of the activity. SeveralVerrucomicrobiawater column phylotypes were affiliated with previously sequenced, glycoside hydrolase-rich genomes of individualVerrucomicrobiacells that bound fluorescently labeled laminarin and xylan and therefore constituted candidates for laminarin and xylan hydrolysis. In sediments, the bacterial community was dominated by different lineages ofVerrucomicrobia,Bacteroidetes, andProteobacteriabut also included members of multiple phylum-level lineages not observed in the water column. This community hydrolyzed laminarin, xylan, chondroitin sulfate, and three additional polysaccharide substrates at high rates. Comparisons with data from the same fjord in the previous summer showed that the bacterial community in Smeerenburgfjord changed in composition, most conspicuously in the changing detection frequency ofVerrucomicrobiain the water column. Nonetheless, in both years the community hydrolyzed the same polysaccharide substrates.
Development and Evaluation of a Novel Multicopy-Element-Targeting Triplex PCR for Detection of Mycobacterium avium subsp. paratuberculosis in Feces
Authors: Sevilla Iker A. , Garrido Joseba M. , Molina Elena , Geijo María V. , Elguezabal Natalia , Vázquez Patricia , Juste Ramón A.
Published: April 2014

The enteropathy called paratuberculosis (PTB), which mainly affects ruminants and has a worldwide distribution, is caused by
Mycobacterium avium
subsp.
paratuberculosis
. This disease significantly reduces the cost-effectiveness of ruminant farms, and therefore, reliable and rapid detection methods are needed to control the spread of the bacterium in livestock and in the environment. The aim of this study was to identify a specific and sensitive combination of DNA extraction and amplification to detect
M. avium
subsp.
paratuberculosis
in feces. Negative bovine fecal samples were inoculated with increasing concentrations of two different bacterial strains (field and reference) to compare the performance of four extraction and five amplification protocols. The best results were obtained using the JohnePrep and MagMax extraction kits combined with an in-house triplex real-time PCR designed to detect IS
900
, IS
Map02
(an insertion sequence of
M. avium
subsp.
paratuberculosis
present in 6 copies per genome), and an internal amplification control DNA simultaneously. These combinations detected 10
M. avium
subsp.
paratuberculosis
cells/g of spiked feces. The triplex PCR detected 1 fg of genomic DNA extracted from the reference strain K10. The performance of the robotized version of the MagMax extraction kit combined with the IS
900
and IS
Map02
PCR was further evaluated using 615 archival fecal samples from the first sampling of nine Friesian cattle herds included in a PTB control program and followed up for at least 4 years. The analysis of the results obtained in this survey demonstrated that the diagnostic method was highly specific and sensitive for the detection of
M. avium
subsp.
paratuberculosis
in fecal samples from cattle and a very valuable tool to be used in PTB control programs.
Identification of Obscure yet Conserved Actin-Associated Proteins in Giardia lamblia
Authors: Paredez Alexander R. , Nayeri Arash , Xu Jennifer W. , Krtková Jana , Cande W. Zacheus
Published: April 2014

Consistent with its proposed status as an early branching eukaryote,
Giardia
has the most divergent actin of any eukaryote and lacks core actin regulators. Although conserved actin-binding proteins are missing from
Giardia
, its actin is utilized similarly to that of other eukaryotes and functions in core cellular processes such as cellular organization, endocytosis, and cytokinesis. We set out to identify actin-binding proteins in
Giardia
using affinity purification coupled with mass spectroscopy (multidimensional protein identification technology [MudPIT]) and have identified >80 putative actin-binding proteins. Several of these have homology to conserved proteins known to complex with actin for functions in the nucleus and flagella. We validated localization and interaction for seven of these proteins, including 14-3-3, a known cytoskeletal regulator with a controversial relationship to actin. Our results indicate that although
Giardia
lacks canonical actin-binding proteins, there is a conserved set of actin-interacting proteins that are evolutionarily indispensable and perhaps represent some of the earliest functions of the actin cytoskeleton.