bluuebunny/crossref_metadata_2025 huggingface dataset:
TH‐C‐213A‐01: Prostate Brachytherapy Ultrasound Quality Assurance Following AAPM TG‐128
Authors: Pfeiffer D , Sutlief S
Published: April 2010

The goal of AAPM Task Group 128 is to provide guidance to physicists who are responsible for the quality assurance of ultrasound units used in prostate brachytherapy. Accurate imaging guidance and dosimetry calculation for prostate brachytherapy depend upon the quality and accuracy of the ultrasound image. Therefore, a robust quality assurance program for the ultrasound system is essential. Completion of the TG‐128 tests requires use of a specialized ultrasound phantom, a water bath, and other equipment. Some care and creativity is needed to complete these tests. Quality assurance should include each link in the process from ultrasound image acquisition to visualization on the treatment planning system. The recommended tests include grayscale visibility, depth of penetration, axial and lateral resolution, distance measurement, area measurement, volume measurement, needle template/electronic grid alignment, and geometric consistency with the treatment planning computer.

Learning Objectives:

1. To describe the methods of TG‐128: Quality assurance tests for prostate brachytherapy ultrasound systems

2. To highlight special techniques which may be used to accomplish the tests described in TG‐128.

3. To assess the relative likelihoods and significance of potential QA findings.

4. To review the materials and time needed to complete the TG‐128 tests.
TH‐C‐213A‐02: Preliminary Report On the Application of TG154 Recommendations in the Clinical Setting
Authors: Molloy J
Published: April 2010

Ultrasound (US) imaging is used in radiotherapy for soft tissue target localization. Its primary application is for prostate localization, but has an evolving role for breast and other treatment sites. Guidance regarding quality assurance of these systems is derived primarily from manufacturer recommendations which vary between systems. US imaging possesses characteristics that differentiate it from other radiotherapy image‐guided localization techniques, including good soft tissue contrast, the absence of additional radiation risk and cost‐effectiveness. Image interpretation can be challenging due to limited penetration depth and image noise. The AAPM charged Task Group 154 to devise quality assurance recommendations for radiotherapy US localization systems.

Guidance regarding periodic quality assurance is provided in the report and will be presented. Emphasis is placed on spatial, mechanical and imaging quality assurance techniques. Recommendations regarding initial user training and ongoing competency credentialing are discussed, as well as practical usage issues that have the potential to improve image quality and localization accuracy. The evolution of the role that US imaging plays in radiotherapy localization is discussed in the context of other image‐guidance techniques, including kV imaging and gold seed markers.

Learning Objectives:

1. Understand the recommended periodic quality assurance procedures for US localization technologies.

2. Become familiar with the role of US localization in the context of other image‐guidance techniques.

3. Understand the importance and structure of user training programs.
TH‐D‐BRD‐04: Increased Tumor Radioresistance by Imaging Doses From Volumetric Image Guided Radiation Therapy
Authors: Yang W , Wang L , Read P , Larner J , Sheng K
Published: April 2010

Purpose: The radiation dose delivered from volumetric imaging guidance is normally between 1–10 cGy, depending on the imaging modalities, tumor sites and patient thickness. To correctly compensate for such doses, their biological effects on tumor and endothelial cells are investigated. Methods and materials: A lung carcinoma cell line (H460), a breast cancer cell line (MCF‐7) and a prostate cancer cell line (PC3) and a human umbilical vein endothelial cell line (HUVEC) were studied for their responses to small doses of radiation ranging from 5 cGy to 50 cGy. Specifically, a MTT assay was used to quantify their proliferation over time. To measure the impact of image guidance doses on cell survival, 5 cGy or 10 cGy were delivered to H460 cells before a 200 cGy therapeutic dose. The tumor cell survival was measured by clonogenic assay and compared with cells that received 200 cGy only. Results: Accelerated proliferation was observed among all tumor cell lines but not the HUVEC to low dose irradiation. The acceleration was statistically significant (p<0.05) for H460 and MFC7 cells but not for the PC3 cells. A 12.6% increase in the H460 cell survival was observed for cells receiving 5cGy before 200 cGy radiation compared to those that received 200 cGy alone (p<0.02), while cells receiving 10 cGy prior to 200 cGy had the same survival as cells receiving 200 cGy alone. Conclusions: Small pre‐treatment doses of radiation may increase the radioresistance of tumor cells. In this study, we demonstrated that the imaging dose from image guided radiation therapy is sufficient to trigger accelerated proliferation when delivered alone and increased tumor survival when delivered prior to a therapeutic dose. Our results suggest that subtracting the imaging dose from the therapeutic dose may adversely affect the tumor control probability.
High-frequency transient evoked otoacoustic emissions acquisition with auditory canal compensated clicks using swept-tone analysis
Authors: Bennett Christopher L. , Özdamar Özcan
Published: April 2010

The meatus (auditory canal) plays a role in altering the waveform of incident sound, distorting time- and frequency-domain characteristics. Often in transient-evoked otoacoustic emission (TEOAE) recording protocols, a 75μs click is utilized to elicit a click-evoked response. TEOAEs are recorded by a probe microphone placed in the meatus and last for about 20ms. Time-domain ringing in the meatal response (MR) creates a stimulus artifact that lasts up to 5+ms, obscuring early-latency TEOAEs. This research is motivated by the need for a real-time, ear and probe placement dependent method for minimizing the magnitude and phase distortions of the meatus. The MR is first obtained using swept-tone analysis, from which a compensated stimulus is created. Usage of a compensated click from normally hearing adult subjects show an improvement to the flatness of the magnitude response and linearization of the phase response. Furthermore, a reduction in effective duration of the MR is found, attenuating the meatal artifact for click stimuli. The high frequency TEOAE content found in the early latencies of the response that is typically obscured by the MR artifact is revealed with the use of a compensated click.
Characteristics of second harmonic generation of Lamb waves in nonlinear elastic plates
Authors: Müller Martin F. , Kim Jin-Yeon , Qu Jianmin , Jacobs Laurence J.
Published: April 2010

This paper investigates the characteristics of the second harmonic generation of Lamb waves in a plate with quadratic nonlinearity. Analytical asymptotic solutions to Lamb waves are first obtained through the use of a perturbation method. Then, based on a careful analysis of these asymptotic solutions, it is shown that the cross-modal generation of a symmetric second harmonic mode by an antisymmetric primary mode is possible. These solutions also demonstrate that modes showing internal resonance—nonzero power flux to the second harmonic mode, plus phase velocity matching—are most useful for measurements. In addition, when using finite wave packets, which is the case in most experimental measurements, group velocity matching is required for a cumulative increase in the second harmonic amplitude with propagation distance. Finally, five mode types (which are independent of material properties) that satisfy all three requirements for this cumulative increase in second harmonic amplitude—nonzero power flux, plus phase and group velocity matching—are identified. These results are important for the development of an experimental procedure to measure material nonlinearity with Lamb waves.
A psychoacoustic method to find the perceptual cues of stop consonants in natural speech
Authors: Li Feipeng , Menon Anjali , Allen Jont B.
Published: April 2010

Synthetic speech has been widely used in the study of speech cues. A serious disadvantage of this method is that it requires prior knowledge about the cues to be identified in order to synthesize the speech. Incomplete or inaccurate hypotheses about the cues often lead to speech sounds of low quality. In this research a psychoacoustic method, named three-dimensional deep search (3DDS), is developed to explore the perceptual cues of stop consonants from naturally produced speech. For a given sound, it measures the contribution of each subcomponent to perception by time truncating, highpass/lowpass filtering, or masking the speech with white noise. The AI-gram, a visualization tool that simulates the auditory peripheral processing, is used to predict the audible components of the speech sound. The results are generally in agreement with the classical studies that stops are characterized by a short duration burst followed by a F2 transition, suggesting the effectiveness of the 3DDS method. However, it is also shown that /ba/ and /pa/ may have a wide band click as the dominant cue. F2 transition is not necessary for the perception of /ta/ and /ka/. Moreover, many stop consonants contain conflicting cues that are characteristic of competing sounds. The robustness of a consonant sound to noise is determined by the intensity of the dominant cue.
One-dimensional transport equation models for sound energy propagation in long spaces: Theory
Authors: Jing Yun , Larsen Edward W. , Xiang Ning
Published: April 2010

In this paper, a three-dimensional transport equation model is developed to describe the sound energy propagation in a long space. Then this model is reduced to a one-dimensional model by approximating the solution using the method of weighted residuals. The one-dimensional transport equation model directly describes the sound energy propagation in the “long” dimension and deals with the sound energy in the “short” dimensions by prescribed functions. Also, the one-dimensional model consists of a coupled set of N transport equations. Only N=1 and N=2 are discussed in this paper. For larger N, although the accuracy could be improved, the calculation time is expected to significantly increase, which diminishes the advantage of the model in terms of its computational efficiency.
Coherent reflection without traveling waves: On the origin of long-latency otoacoustic emissions in lizards
Authors: Bergevin Christopher , Shera Christopher A.
Published: April 2010

Lizard ears produce otoacoustic emissions with characteristics often strikingly reminiscent of those measured in mammals. The similarity of their emissions is surprising, given that lizards and mammals manifest major differences in aspects of inner ear morphology and function believed to be relevant to emission generation. For example, lizards such as the gecko evidently lack traveling waves along their basilar membrane. Despite the absence of traveling waves, the phase-gradient delays of gecko stimulus-frequency otoacoustic emissions (SFOAEs) are comparable to those measured in many mammals. This paper describes a model of emission generation inspired by the gecko inner ear. The model consists of an array of coupled harmonic oscillators whose effective damping manifests a small degree of irregularity. Model delays increase with the assumed sharpness of tuning, reflecting the build-up time associated with mechanical resonance. When tuning bandwidths are chosen to match those of gecko auditory-nerve fibers, the model reproduces the major features of gecko SFOAEs, including their spectral structure and the magnitude and frequency dependence of their phase-gradient delays. The same model with appropriately modified parameters reproduces the features of SFOAEs in alligator lizards. Analysis of the model demonstrates that the basic mechanisms operating in the model are similar to those of the coherent-reflection model developed to describe mammalian emissions. These results support the notion that SFOAE delays provide a noninvasive measure of the sharpness of cochlear tuning.
Dependence of phonation threshold pressure and frequency on vocal fold geometry and biomechanics
Authors: Zhang Zhaoyan
Published: April 2010

Previous studies show that phonation onset occurs as two eigenmodes of the vocal folds are synchronized by the interaction between the vocal folds and the glottal flow. This study examines the influence of the geometrical and biomechanical properties of the vocal folds on this eigenmode-synchronization process, with a focus on phonation threshold pressure and frequency. The analysis showed that phonation threshold pressure was determined by the frequency spacing and coupling strength between the two natural modes that were synchronized by the fluid-structure interaction. The phonation frequency at onset was the root mean square value of the two natural frequencies plus a correction due to the added stiffness of the glottal flow. When higher-order modes of the vocal fold structure were included, more than one group of eigenmodes was synchronized as the system moved toward phonation onset. Changes in vocal fold biomechanics may change the relative dominance between different groups and cause phonation onset to occur at a different eigenmode, which was often accompanied by an abrupt change in onset frequency. Due to the synchronization of multiple pairs of eigenmodes and the mode-switching possibility, a complete and accurate description of vocal fold biomechanical properties is needed to determine the final synchronization pattern and obtain a reliable calculation of the dependence of phonation threshold pressure and frequency on vocal fold geometry and other biomechanical properties.
Whistle emissions of Indo-Pacific bottlenose dolphins (Tursiops aduncus) differ with group composition and surface behaviors
Authors: Hawkins Elizabeth R. , Gartside Donald F.
Published: April 2010

The intricate and highly developed acoustic communication system of bottlenose dolphins reflects the complexities of their social organization. Indo-Pacific bottlenose dolphins (Tursiops aduncus) produce numerous types of acoustic emissions, including a diverse repertoire of whistles used for communicative purposes. The influence of group composition on whistle production and the function of different whistles produced by dolphins in wild contexts are relatively unknown. Recordings of acoustic emissions and behavior of dolphins were made concurrently during vessel-based surveys along the coast of northern New South Wales, Australia. Whistles were divided into five tonal classes (sine, rise, down-sweep, flat, and concave) and categorized into distinct whistle types. It is shown that while whistle repetition rate and whistle diversity was influenced by group composition, it is not influenced by behavior. Noncalf groups produced a significantly higher whistle repetition rate and whistle diversity than calf groups. In contrast, the types of whistles produced were related to the behavior in which the dolphins were engaged in: some tonal classes and distinct whistle types were related to different behavior states. Findings suggested that some whistle types may be used to communicate specific information on the behavioral context of the individuals involved.
Whistles emitted by Atlantic spotted dolphins (Stenella frontalis) in southeastern Brazil
Authors: Azevedo Alexandre F. , Flach L. , Bisi Tatiana L. , Andrade Luciana G. , Dorneles Paulo R. , Lailson-Brito J.
Published: April 2010

The whistles of Atlantic spotted dolphins have been studied in a few localities of the North Atlantic Ocean and those studies revealed that the species emits whistles within a broad frequency range, with a high number of inflection points and presence of harmonics. In the South Atlantic Ocean, there is no information about the sounds produced by Atlantic spotted dolphins. A total of 1092 whistles emitted by free-ranging Atlantic spotted dolphins in Southeastern Brazilian coastal waters were analyzed. Whistles recorded in this study had a broad frequency range from 1.15 to 23.44 kHz. Whistles without harmonics were frequently emitted (N=701; 64.2%) and those signals with zero up to two inflection points corresponded to 94% of all whistles. Some differences in whistle characteristics (inflection points and duration) were found in relation to areas in North Atlantic Ocean and whistles were shorter and with a smaller number of inflection points in Brazil. Whistles produced by Atlantic spotted dolphins varied between the two behavioral states in which dolphins were engaged. Whistles were more frequently emitted when dolphins presented behaviors that included fast movement at surface, prey pursuit, aerial behavior, and physical contact. In these situations, whistles were on average longer and had higher frequency parameters than those emitted when animals were engaged in slowly and moderate traveling. The findings presented herewith reveal that dolphins modified whistle structures within behavioral states.
The effect of whisper and creak vocal mechanisms on vocal tract resonances
Authors: Swerdlin Yoni , Smith John , Wolfe Joe
Published: April 2010

The frequencies of vocal tract resonances estimated using whisper and creak phonations are compared with those in normal phonation for subjects who produced pairs of these phonations in the same vocal gesture. Peaks in the spectral envelope were used to measure the frequencies of the first four resonances (R1–R4) for the non-periodic phonations, and broadband excitation at the mouth was used to measure them with similar precision in normal phonation. For resonances R1–R4, whispering raises the average resonant frequencies by 255 Hz with standard deviation 90 Hz, 115±105, 125±125, and 75±120 Hz, respectively. A simple one dimensional model of the vocal tract is presented and used to show how an effective glottal area can be estimated from shifts in resonance frequency measured during the same vocal gesture. Calculations suggest that the effective glottal area thus defined increases to 40±30 mm2 during whispering. Creak phonation raised significantly only the first and third resonant frequencies, by 45±50 and 65±120 Hz respectively. It thus appears possible to use creak phonation to determine resonances with more precision than is available from the spectral envelope of voiced speech, and this supports its use in teaching resonance tuning to singers.
A new adaptive resonance frequency of piezoelectric components used for vibration damping
Authors: Faiz A. , Petit L. , Guyomar D. , Ducourneau J.
Published: April 2010

This paper describes two methods for vibration damping in a broad band frequency range using a piezoelectric patch. The first method, applied to an adaptive device, uses a bias (static voltage control), which applies stresses or releases stresses in a piezoelectric component to modify its mechanical characteristics and thereby its resonance frequency. The second method is based on a semipassive approach [synchronized switch damping (SSD)], developed to control structural vibration damping using a piezoelectric component. Attenuations of 10 and 4.8 dB in vibration velocity have been obtained using the adaptive frequency and SSD methods.
Physically constrained maximum likelihood mode filtering
Authors: Papp Joseph C. , Preisig James C. , Morozov Andrey K.
Published: April 2010

Mode filtering is most commonly implemented using the sampled mode shapes or pseudoinverse algorithms. Buck et al. [J. Acoust. Soc. Am. 103, 1813–1824 (1998)] placed these techniques in the context of a broader maximum a posteriori (MAP) framework. However, the MAP algorithm requires that the signal and noise statistics be known a priori. Adaptive array processing algorithms are candidates for improving performance without the need for a priori signal and noise statistics. A variant of the physically constrained, maximum likelihood (PCML) algorithm [A. L. Kraay and A. B. Baggeroer, IEEE Trans. Signal Process. 55, 4048–4063 (2007)] is developed for mode filtering that achieves the same performance as the MAP mode filter yet does not need a priori knowledge of the signal and noise statistics. The central innovation of this adaptive mode filter is that the received signal’s sample covariance matrix, as estimated by the algorithm, is constrained to be that which can be physically realized given a modal propagation model and an appropriate noise model. Shallow water simulation results are presented showing the benefit of using the PCML method in adaptive mode filtering.
Multimode radiation from an unflanged, semi-infinite circular duct with uniform flow
Authors: Sinayoko Samuel , Joseph Phillip , McAlpine Alan
Published: April 2010

Multimode sound radiation from an unflanged, semi-infinite, rigid-walled circular duct with uniform subsonic mean flow everywhere is investigated theoretically. The multimode directivity depends on the amplitude and directivity function of each individual cut-on mode. The amplitude of each mode is expressed as a function of cut-on ratio for a uniform distribution of incoherent monopoles, a uniform distribution of incoherent axial dipoles, and for equal power per mode. The directivity function of each mode is obtained by applying a Lorentz transformation to the zero-flow directivity function, which is given by a Wiener–Hopf solution. This exact numerical result is compared to an analytic solution, valid in the high-frequency limit, for multimode directivity with uniform flow. The high-frequency asymptotic solution is derived assuming total transmission of power at the open end of the duct, and gives the multimode directivity function with flow in the forward arc for a general family of mode amplitude distribution functions. At high frequencies the agreement between the exact and asymptotic solutions is shown to be excellent.
Experimental modeling and design optimization of push-pull electret loudspeakers
Authors: Bai Mingsian R. , Wang Chun-Jen , Chiang Dar-Ming , Lin Shu-Ru
Published: April 2010

A fully experimental modeling technique and a design optimization procedure are presented in this paper for push-pull electret loudspeakers. Conventional electrical impedance-based parameter identification methods are not completely applicable to electret speakers due to the extremely weak electromechanical coupling. This prompts the development of an experimental technique for identifying the electroacoustic parameters of the electret speakers. Mechanical parameters are identified from the membrane velocity measured using a laser vibrometer. The voltage-force conversion factor and the motional impedance are estimated, with the aid of a test-box method. This experimentally identified model serves as the simulation platform for predicting the response of the electret loudspeaker and optimizing the design. Optimal parameters are calculated by using the simulated annealing (SA) algorithm to fulfill various design goals and constraints. Either the comprehensive search for various parameters or the simple search for the optimal gap distance can be conducted by this SA procedure. The results reveal that the optimized design has effectively enhanced the performance of the electret loudspeaker.
Are urban noise pollution levels decreasing?
Authors: Arana M.
Published: April 2010

The majority of acoustic impact studies developed over the last 50 years have used a similar acoustic parameter (Leq, Ldn) but the noise mapping methodology has been very uneven. The selection of the measurement points, the measurement periods, or the evaluation indices have not followed a unique criterion. Therefore, it is not possible to compare the sound pollution levels between different cities from those studies, at least in a rigorous sense. Even more, different studies carried out in the same city by different researchers during different years and using different methodologies are not conclusive whether the acoustic pollution increases or decreases. The present paper shows results, with statistical significance, about the evolution of the acoustic pollution obtained for two Spanish cities, Pamplona and Madrid. In both cases, it can be concluded that noise pollution decreases over time (P<0.01).
Third- and fourth-order elasticities of biological soft tissues
Authors: Destrade Michel , Gilchrist Michael D. , Ogden Raymond W.
Published: April 2010

In the theory of weakly nonlinear elasticity, Hamilton et al. [J. Acoust. Soc. Am. 116, 41–44 (2004)] identified W=μI2+(A/3)I3+DI22 as the fourth-order expansion of the strain-energy density for incompressible isotropic solids. Subsequently, much effort focused on theoretical and experimental developments linked to this expression in order to inform the modeling of gels and soft biological tissues. However, while many soft tissues can be treated as incompressible, they are not in general isotropic, and their anisotropy is associated with the presence of oriented collagen fiber bundles. Here the expansion of W is carried up to fourth order in the case where there exists one family of parallel fibers in the tissue. The results are then applied to acoustoelasticity, with a view to determining the second- and third-order nonlinear constants by employing small-amplitude transverse waves propagating in a deformed soft tissue.
Response to “Comments on ‘Pore fluid viscosity and the wave properties of saturated granular materials including marine sediments [J. Acoust. Soc. Am. 127, 2095–2098 (2010)]’ ”
Authors: Buckingham Michael J.
Published: April 2010

Chotiros and Isakson [J. Acoust. Soc. Am. 127, 2095–2098 (2010)] raised three main issues concerning the grain-shearing and viscous-grain-shearing (VGS) theories of wave propagation in saturated marine sediments. (1) They introduced the R-ratio as a test of the two theories, (2) they then used the R-ratio to compare the theories with published measurements of compressional and shear wave properties of laboratory sediments under high confinement pressures, and (3) they pointed out that the VGS theory overestimates the shear attenuation measured during the Sediment Acoustics Experiment 1999 (SAX99) by about an order of magnitude. With regard to the R-ratio, it provides an incomplete test of the theories and, moreover, it returns ambiguous results. As for the tests against measurements made under high confinement pressures, they are invalid because the theories are not applicable under such conditions. The third point is correct, but a minor modification to the VGS theory resolves the difficulty.
Masked speech priming: Neighborhood size matters
Authors: Davis Chris , Kim Jeesun , Barbaro Angelo
Published: April 2010

The current study investigated the robustness of priming from a masked speech priming method introduced by Kouider and Dupoux [(2005). Psychol. Sci. 16, 617–625]. In this procedure, a compressed spoken prime is embedded in auditory masking stimuli and presented immediately prior to an uncompressed auditory target. The degree to which spoken stimuli could be compressed without significant data loss was first determined. Using this compression level, repetition and form priming were measured for the target words with a high versus low number of phonological neighbors. The results indicated that robust masked speech priming occurred only for word targets that had few neighbors.
Regulation of G Protein–Coupled Receptor Signaling: Specific Dominant-Negative Effects of Melanocortin 2 Receptor Accessory Protein 2
Authors: Sebag Julien A. , Hinkle Patricia M.
Published: April 2010

Two homologous accessory proteins exert opposing effects on the responsiveness of the melanocortin 2 receptor to the hormone ACTH.
Rod-Derived Cone Viability Factor for Treating Blinding Diseases: From Clinic to Redox Signaling
Authors: Léveillard Thierry , Sahel José-Alain
Published: April 2010

A neuroprotective protein may be broadly useful for treating
degenerative retinal diseases caused by mutations in a number of
different genes.
Training Translators for Smart Drug Discovery
Authors: Skarke Carsten , FitzGerald Garret A.
Published: April 2010

Human capital is a rate-limiting constraint in translational medicine
and therapeutics.
Microbial Links between Sulfate Reduction and Metal Retention in Uranium- and Heavy Metal-Contaminated Soil
Authors: Sitte Jana , Akob Denise M. , Kaufmann Christian , Finster Kai , Banerjee Dipanjan , Burkhardt Eva-Maria , Kostka Joel E. , Scheinost Andreas C. , Büchel Georg , Küsel Kirsten
Published: April 2010

Sulfate-reducing bacteria (SRB) can affect metal mobility either directly by reductive transformation of metal ions, e.g., uranium, into their insoluble forms or indirectly by formation of metal sulfides. This study evaluated
in situ
and biostimulated activity of SRB in groundwater-influenced soils from a creek bank contaminated with heavy metals and radionuclides within the former uranium mining district of Ronneburg, Germany.
In situ
activity of SRB, measured by the
35
SO
4
2−
radiotracer method, was restricted to reduced soil horizons with rates of ≤142 ± 20 nmol cm
−3
day
−1
. Concentrations of heavy metals were enriched in the solid phase of the reduced horizons, whereas pore water concentrations were low. X-ray absorption near-edge structure (XANES) measurements demonstrated that ∼80% of uranium was present as reduced uranium but appeared to occur as a sorbed complex. Soil-based
dsrAB
clone libraries were dominated by sequences affiliated with members of the
Desulfobacterales
but also the
Desulfovibrionales
,
Syntrophobacteraceae
, and
Clostridiales
. [
13
C]acetate- and [
13
C]lactate-biostimulated soil microcosms were dominated by sulfate and Fe(III) reduction. These processes were associated with enrichment of SRB and
Geobacteraceae
; enriched SRB were closely related to organisms detected in soils by using the
dsrAB
marker. Concentrations of soluble nickel, cobalt, and occasionally zinc declined ≤100% during anoxic soil incubations. In contrast to results in other studies, soluble uranium increased in carbon-amended treatments, reaching ≤1,407 nM in solution. Our results suggest that (i) ongoing sulfate reduction in contaminated soil resulted in
in situ
metal attenuation and (ii) the fate of uranium mobility is not predictable and may lead to downstream contamination of adjacent ecosystems.
Nonmagnetotactic Multicellular Prokaryotes from Low-Saline, Nonmarine Aquatic Environments and Their Unusual Negative Phototactic Behavior
Authors: Lefèvre Christopher T. , Abreu Fernanda , Lins Ulysses , Bazylinski Dennis A.
Published: April 2010

Magnetotactic multicellular prokaryotes (MMPs) are unique magnetotactic bacteria of theDeltaproteobacteriaclass and the first found to biomineralize the magnetic mineral greigite (Fe3S4). Thus far they have been reported only from marine habitats. We questioned whether MMPs exist in low-saline, nonmarine environments. MMPs were observed in samples from shallow springs in the Great Boiling Springs geothermal field and Pyramid Lake, both located in northwestern Nevada. The temperature at all sites was ambient, and salinities ranged from 5 to 11 ppt. These MMPs were not magnetotactic and did not contain magnetosomes (called nMMPs here). nMMPs ranged from 7 to 11 μm in diameter, were composed of about 40 to 60 Gram-negative cells, and were motile by numerous flagella that covered each cell on one side, characteristics similar to those of MMPs. 16S rRNA gene sequences of nMMPs show that they form a separate phylogenetic branch within the MMP group in theDeltaproteobacteriaclass, probably representing a single species. nMMPs exhibited a negative phototactic behavior to white light and to wavelengths of ≤480 nm (blue). We devised a “light racetrack” to exploit this behavior, which was used to photoconcentrate nMMPs for specific purposes (e.g., DNA extraction) even though their numbers were low in the sample. Our results show that the unique morphology of the MMP is not restricted to marine and magnetotactic prokaryotes. Discovery of nonmagnetotactic forms of the MMP might support the hypothesis that acquisition of the magnetosome genes involves horizontal gene transfer. To our knowledge, this is the first report of phototaxis in bacteria of theDeltaproteobacteriaclass.
Application of Real-Time PCR To Estimate Toxin Production by the Cyanobacterium
Planktothrix
sp
Authors: Ostermaier Veronika , Kurmayer Rainer
Published: April 2010

Quantitative real-time PCR methods are increasingly being applied for the enumeration of toxic cyanobacteria in the environment. However, to justify the use of real-time PCR quantification as a monitoring tool, significant correlations between genotype abundance and actual toxin concentrations are required. In the present study, we aimed to explain the concentrations of three structural variants of the hepatotoxin microcystin (MC) produced by the filamentous cyanobacterium
Planktothrix
sp., [Asp, butyric acid (Dhb)]-microcystin-RR (where RR means two arginines), [Asp, methyl-dehydro-alanine (Mdha)]-microcystin-RR, and [Asp, Dhb]-microcystin-homotyrosine-arginine (HtyR), by the abundance of the microcystin genotypes encoding their synthesis. Three genotypes of microcystin-producing cyanobacteria (denoted the Dhb, Mdha, and Hty genotypes) in 12 lakes of the Alps in Austria, Germany, and Switzerland from 2005 to 2007 were quantified by means of real-time PCR. Their absolute and relative abundances were related to the concentration of the microcystin structural variants in aliquots determined by high-performance liquid chromatography (HPLC). The total microcystin concentrations varied from 0 to 6.2 μg liter
−1
(mean ± standard error [SE] of 0.6 ± 0.1 μg liter
−1
) among the samples, in turn resulting in an average microcystin content in
Planktothrix
of 3.1 ± 0.7 μg mm
−3
biovolume. Over a wide range of the population density (0.001 to 3.6 mm
3
liter
−1
Planktothrix
biovolume), the Dhb genotype and [Asp, Dhb]-MC-RR were most abundant, while the Hty genotype and MC-HtyR were found to be in the lowest proportion only. In general, there was a significant linear relationship between the abundance/proportion of specific microcystin genotypes and the concentration/proportion of the respective microcystin structural variants on a logarithmic scale. We conclude that estimating the abundance of specific microcystin genotypes by quantitative real-time PCR is useful for predicting the concentration of microcystin variants in water.
Using Epstein-Barr Viral Load Assays To Diagnose, Monitor, and Prevent Posttransplant Lymphoproliferative Disorder
Authors: Gulley Margaret L. , Tang Weihua
Published: April 2010

Epstein-Barr virus (EBV) DNA measurement is being incorporated into routine medical practice to help diagnose, monitor, and predict posttransplant lymphoproliferative disorder (PTLD) in immunocompromised graft recipients. PTLD is an aggressive neoplasm that almost always harbors EBV DNA within the neoplastic lymphocytes, and it is often fatal if not recognized and treated promptly. Validated protocols, commercial reagents, and automated instruments facilitate implementation of EBV load assays by real-time PCR. When applied to either whole blood or plasma, EBV DNA levels reflect clinical status with respect to EBV-related neoplasia. While many healthy transplant recipients have low viral loads, high EBV loads are strongly associated with current or impending PTLD. Complementary laboratory assays as well as histopathologic examination of lesional tissue help in interpreting modest elevations in viral load. Circulating EBV levels in serial samples reflect changes in tumor burden and represent an effective, noninvasive tool for monitoring the efficacy of therapy. In high-risk patients, serial testing permits early clinical intervention to prevent progression toward frank PTLD. Restoring T cell immunity against EBV is a major strategy for overcoming PTLD, and novel EBV-directed therapies are being explored to thwart virus-driven neoplasia.
Schistosomiasis in the People's Republic of China: the Era of the Three Gorges Dam
Authors: McManus Donald P. , Gray Darren J. , Li Yuesheng , Feng Zheng , Williams Gail M. , Stewart Donald , Rey-Ladino Jose , Ross Allen G.
Published: April 2010

The potential impact of the Three Gorges Dam (TGD) on schistosomiasis transmission in China has invoked considerable global concern. The TGD will result in changes in the water level and silt deposition downstream, favoring the reproduction of
Oncomelania
snails. Combined with blockages of the Yangtze River's tributaries, these changes will increase the schistosomiasis transmission season within the marshlands along the middle and lower reaches of the Yangtze River. The changing schistosome transmission dynamics necessitate a comprehensive strategy to control schistosomiasis. This review discusses aspects of the epidemiology and transmission of
Schistosoma japonicum
in China and considers the pathology, clinical outcomes, diagnosis, treatment, immunobiology, and genetics of schistosomiasis japonica together with an overview of current progress in vaccine development, all of which will have an impact on future control efforts. The use of synchronous praziquantel (PZQ) chemotherapy for humans and domestic animals is only temporarily effective, as schistosome reinfection occurs rapidly. Drug delivery requires a substantial infrastructure to regularly cover all parts of an area of endemicity. This makes chemotherapy expensive and, as compliance is often low, a less than satisfactory control option. There is increasing disquiet about the possibility that PZQ-resistant schistosomes will develop. Consequently, as mathematical modeling predicts, vaccine strategies represent an essential component in the future control of schistosomiasis in China. With the inclusion of focal mollusciciding, improvements in sanitation, and health education into the control scenario, China's target of reducing the level of schistosome infection to less than 1% by 2015 may be achievable.
The Changing Microbial Epidemiology in Cystic Fibrosis
Authors: LiPuma John J.
Published: April 2010

Infection of the airways remains the primary cause of morbidity and mortality in persons with cystic fibrosis (CF). This review describes salient features of the epidemiologies of microbial species that are involved in respiratory tract infection in CF. The apparently expanding spectrum of species causing infection in CF and recent changes in the incidences and prevalences of infection due to specific bacterial, fungal, and viral species are described. The challenges inherent in tracking and interpreting rates of infection in this patient population are discussed.
Bacillus cereus, a Volatile Human Pathogen
Authors: Bottone Edward J.
Published: April 2010

Bacillus cereusis a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. WhileB. cereusis associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal non-gastrointestinal-tract infections. The pathogenicity ofB. cereus, whether intestinal or nonintestinal, is intimately associated with the production of tissue-destructive exoenzymes. Among these secreted toxins are four hemolysins, three distinct phospholipases, an emesis-inducing toxin, and proteases. The major hurdle in evaluatingB. cereuswhen isolated from a clinical specimen is overcoming its stigma as an insignificant contaminant. Outside its notoriety in association with food poisoning and severe eye infections, this bacterium has been incriminated in a multitude of other clinical conditions such as anthrax-like progressive pneumonia, fulminant sepsis, and devastating central nervous system infections, particularly in immunosuppressed individuals, intravenous drug abusers, and neonates. Its role in nosocomial acquired bacteremia and wound infections in postsurgical patients has also been well defined, especially when intravascular devices such as catheters are inserted. Primary cutaneous infections mimicking clostridial gas gangrene induced subsequent to trauma have also been well documented.B. cereusproduces a potent β-lactamase conferring marked resistance to β-lactam antibiotics. Antimicrobials noted to be effective in the empirical management of aB. cereusinfection while awaiting antimicrobial susceptibility results for the isolate include ciprofloxacin and vancomycin.
Cultivation and Genomic, Nutritional, and Lipid Biomarker Characterization of
Roseiflexus
Strains Closely Related to Predominant
In Situ
Populations Inhabiting Yellowstone Hot Spring Microbial Mats
Authors: van der Meer Marcel T. J. , Klatt Christian G. , Wood Jason , Bryant Donald A. , Bateson Mary M. , Lammerts Laurens , Schouten Stefan , Sinninghe Damsté Jaap S. , Madigan Michael T. , Ward David M.
Published: April 2010

Roseiflexus
sp. strains were cultivated from a microbial mat of an alkaline siliceous hot spring in Yellowstone National Park. These strains are closely related to predominant filamentous anoxygenic phototrophs found in the mat, as judged by the similarity of small-subunit rRNA, lipid distributions, and genomic and metagenomic sequences. Like a Japanese isolate,
R. castenholzii
, the Yellowstone isolates contain bacteriochlorophyll
a
, but not bacteriochlorophyll
c
or chlorosomes, and grow photoheterotrophically or chemoheterotrophically under dark aerobic conditions. The genome of one isolate,
Roseiflexus
sp. strain RS1, contains genes necessary to support these metabolisms. This genome also contains genes encoding the 3-hydroxypropionate pathway for CO
2
fixation and a hydrogenase, which might enable photoautotrophic metabolism, even though neither isolate could be grown photoautotrophically with H
2
or H
2
S as a possible electron donor. The isolates exhibit temperature, pH, and sulfide preferences typical of their habitat. Lipids produced by these isolates matched much better with mat lipids than do lipids produced by
R. castenholzii
or
Chloroflexus
isolates.
Rehabilitation of shoulder impingement syndrome and rotator cuff injuries: an evidence-based review
Authors: Ellenbecker Todd S , Cools Ann
Published: April 2010

Rehabilitation of the patient with glenohumeral impingement requires a complete understanding of the structures involved and the underlying mechanism creating the impingement response. A detailed clinical examination and comprehensive treatment programme including specific interventions to address pain, scapular dysfunction and rotator cuff weakness are recommended. The inclusion of objective testing to quantify range of motion and both muscular strength and balance in addition to the manual orthopaedic clinical tests allows clinicians to design evidencebased rehabilitation programmes as well as measure progression and patient improvement.
The effects of an exercise intervention on forward head and rounded shoulder postures in elite swimmers
Authors: Lynch Stephanie S , Thigpen Charles A , Mihalik Jason P , Prentice William E , Padua Darin
Published: April 2010

Objectives

To examine the correction of posture, increase in strength and decrease in shoulder pain and dysfunction in varsity swimmers.

Design and Setting

Randomised clinical trial.

Participants

Twenty-eightNational Collegiate Athletic Associationdivision I varsity swimmers.

Measurements

Two testing sessions were conducted before and after an 8-week time period. Posture, strength and shoulder pain and function were assessed. Forward head angle was measured using a digital inclinometer, forward head translation was measured using a ruler and total scapular distance was measured with unmarked string. Average and peak values (N) of strength were measured with the hand-held dynamometer. The intervention subjects then participated in an 8-week exercise training programme to correct posture. The procedures were then repeated in the post-test.

Results

Significant group by time interactions (p<0.05) were found in forward head angle and forward shoulder translation indicating a decrease in forward head angle and forward shoulder translation. Significant main effects for time (p<0.05) were found in strength measures for all muscle groups indicating increased strength for shoulder girdle muscles tested.

Conclusions

The exercise intervention was successful at decreasing forward head and rounded shoulder postures in elite swimmers. This study supports the theoretical basis for clinical rehabilitation of posture and the shoulder.
A workplace intervention for sick-listed employees with distress: results of a randomised controlled trial
Authors: van Oostrom Sandra H , van Mechelen Willem , Terluin Berend , de Vet Henrica C W , Knol Dirk L , Anema Johannes R
Published: April 2010

Objectives

To evaluate the effectiveness of a participatory workplace intervention compared with usual care for sick-listed employees with distress, with regard to return to work (RTW) within the 12-month follow-up.

Methods

Employees with distress and sick-listed for 2–8 weeks were randomised to a workplace intervention (n=73) or to usual care (n=72). The participatory workplace intervention is a stepwise process involving the sick-listed employee and their supervisor, aimed at reducing obstacles for RTW by reaching consensus about an action plan for RTW. Outcome variables were lasting RTW, cumulative sickness absence and stress-related symptoms.

Results

Overall, an HR of 0.99 (95% CI 0.70 to 1.39) indicated no effect of the workplace intervention on lasting RTW. However, the workplace intervention significantly reduced the time until lasting RTW for employees who at baseline intended to return to work despite symptoms with an HR of 2.05 (95% CI 1.22 to 3.45). Employees who intended to return to work despite symptoms returned to work after 55 days in the workplace intervention group and 120 days in the usual care group. No such effect of the intervention was found for employees without baseline intentions to return to work despite symptoms (HR=0.78, 95% CI 0.47 to 1.28).

Conclusions

No overall effect of the participatory workplace intervention on lasting RTW was found. The workplace intervention appeared effective on lasting RTW for employees who at baseline intended to return to work despite symptoms. For employees who showed no baseline intention to return to work, the intervention did not have any effect. Other approaches are needed for this subgroup.

This trial has been registered at the Dutch National Trial Register

ISRCTN92307123.
Drained instability of sand in plane strain
Authors: Wanatowski Dariusz , Chu Jian , Loke Wai Lay
Published: April 2010

Flowslide or failure of loose granular soil slopes is often explained using liquefaction or instability data obtained from undrained triaxial tests. However, under static loading conditions, the assumption of an undrained condition is not realistic for sand, particularly clean sand. Case studies have indicated that instability of granular soil can occur under essentially drained conditions (e.g., the Wachusett Dam failure in 1907). Laboratory studies on Changi sand by Chu et al. in 2003 have shown that sand can become unstable under completely drained conditions. However, these studies were carried out under axisymmetric conditions and thus, cannot be applied directly to the analysis of slope failures. In this paper, experimental data obtained from plane-strain tests are presented to study the instability behaviour of loose and dense sand under plane-strain conditions. Based on these test data, the conditions for the occurrence of drained instability in plane strain are established. Using the modified state parameter, the conditions for instability under both axisymmetric and plane-strain conditions can be unified. A framework for interpreting the instability conditions of sandy slopes developed under axisymmetric conditions also extends into plane-strain conditions.