bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear compressional waves in marine sediments
Authors: McDonald B. Edward
Published: October 2013

A theory for nonlinear waves in marine sediments must account for the presence of a granular frame filled with water and possibly gas bubbles. When grains are in full contact, the stress–strain relation for the sediment contains a contribution varying as strain to the power 3/2, referred to as the Hertz force. The quadratic nonlinearity parameter derived from the second pressure derivative with respect to density thus diverges in the limit of small strain. We present a simple nonlinear wave equation model (a variant of the NPE) for compressional waves in marine sediments that avoids Taylor expansion and the problem of diverging nonlinearity parameter. An equation of state for partially consolidated sediments is derived from consolidation test results. Pressure is found to increase with overdensity to the power 5/2, indicating an increase in the number of contacts per grain as density increases. Numerical results for nonlinear compressional waves show agreement with analytic self-similar profiles derived from the nonlinear wave equation. [Work supported by the ONR.]
An autonomous underwater vehicle technique for in situ waveguide characterization
Authors: Holmes Jason D. , Carey William M. , Lynch James F.
Published: October 2013

Results from an autonomous underwater vehicle (AUV) towed hydrophone array experiment are presented as a demonstration of a new in situ measurement technique. In this technique, a source is deployed from a small vessel and the AUV navigates along a pre-programmed path towing the hydrophone array. The added degrees of freedom associated with an array towed by an AUV provides for rapid characterization of the shallow-water waveguide. Using a synthetic aperture, the horizontal wave number spectrum is measured and the modal eigenvalues are experimentally measured by picking off the peak locations in the wave number spectrum. The modal amplitudes are found by using the finite aperture array approximation to the Hankel transform in which the amplitude of the spectral peaks are finite and proportional to the mode excitation amplitude as shown by Frisk et al. [J. Acoust. Soc. Am. 86, 1928–1939 (1989)]. By measuring the modal attenuation, one can determine the effects of bottom interaction. Another measurement technique using the same towed hydrophone system is described in which signal path bottom reflection results are obtained using a parametric source.
Prediction of airplane aft-cabin noise using statistical energy analysis
Authors: Fung Andrew K. , Davis Evan B.
Published: October 2013

Statistical energy analysis (SEA) predictions of turbulent boundary layer and engine exhaust noise in the aft cabin of an airplane have been made and compared to flight data. Measurements of engine shock-cell sound pressure levels, characterized by relatively long correlation lengths and circumferential and axial variation along the fuselage surface, were extrapolated and used as source inputs to an SEA model of a widebody airplane fuselage. Turbulent boundary layer pressure fluctuations, characterized by relatively short circumferential correlation lengths and uniformity over the aft fuselage, were represented using Efimtsov empirical correlation functions. Model variance was predicted using the Langley method and combined with estimates of measurement uncertainty to verify the prediction process.
On spectral and amplitude properties of first- and zeroth- order head waves, and implications for geoacoustic inversion
Authors: Choi Jee Woong , Dahl Peter H.
Published: October 2013

Head waves and ground waves are strongly linked with properties of the seabed, and thus provide a useful measure for geoacoustic inversion. For a Pekeris waveguide, the ground wave can be interpreted as sequence of first-order (or classical) head waves, called a head-wave sequence [Choi and Dahl, J. Acoust. Soc. Am. 116, 2529 (2004)]. (The term first-order originates from a ray series classification.) The presence of a sound-speed gradient in the sediment gives rise to very different effects. Here, the first-order head wave is replaced by either a lower-amplitude interference head wave whose properties are akin to a first-order head wave, or a higher-amplitude interference head wave or related diving wave whose properties are zeroth-order. There is also a shift in the dominant frequency of the first-arriving head wave in the transition regime between these arrivals. In this talk, nomenclature for head waves based on the ray series classification is suggested, parametric dependencies for distinguishing these arrivals are discussed, the criterion to estimate the frequency shift is presented, and some implications for geoacoustic parameter estimation are discussed. Synthetic data and results are obtained using the RAM parabolic equation algorithm. [Research supported by ONR Ocean Acoustics.]
A unified approach for the spatial enhancement of sound
Authors: Choi Joung-Woo , Jang Ji-Ho , Kim Yang-Hann
Published: October 2013

This paper aims to control the sound field spatially, so that the desired or target acoustic variable is enhanced within a zone where a listener is located. This is somewhat analogous to having manipulators that can draw sounds in any place. This also means that one can somehow see the controlled shape of sound in frequency or in real time. The former assures its practical applicability, for example, listening zone control for music. The latter provides a mean of analyzing sound field. With all these regards, a unified approach is proposed that can enhance selected acoustic variables using multiple sources. Three kinds of acoustic variables that have to do with magnitude and direction of sound field are formulated and enhanced. The first one, which has to do with the spatial control of acoustic potential energy, enables one to make a zone of loud sound over an area. Otherwise, one can control directional characteristic of sound field by controlling directional energy density, or one can enhance the magnitude and direction of sound at the same time by controlling acoustic intensity. Throughout various examples, it is shown that these acoustic variables can be controlled successfully by the proposed approach.
Deconvolution for interference cancellation in underwater acoustics using Gibbs sampling
Authors: Michalopoulou Zoi-Heleni
Published: October 2013

Loud interfering sources often hinder efforts to localize a quiet source in shallow-water environments. Interference cancellation methods are sought that remove the field component from the extraneous sources, leaving the contribution of the source of interest intact as much as possible; this latter contribution can then be used for source localization using matched-field methods. In this work we develop a method that estimates locations and spectral characteristics (amplitude and phase) of multiple sources; the number of sources is estimated as well. The procedure is optimized with Gibbs sampling and is, in essence, a deconvolution process, since source amplitude and phase information is recovered. We find that the parameters of the strongest sources can be reliably estimated within a few iterations. The field components attributed to those interfering sources are then estimated and removed from the total acoustic field; the remaining field component can be readily used for localization of the quiet source(s) using a simple Bartlett processor. [Work supported by ONR.]
Comparison of Helmholtz equation least squares and other methods in diagnosing stationary and nonstationary vehicle noises
Authors: Wu Sean
Published: October 2013

This paper gives a brief overview of current near-field acoustic holography (NAH) techniques. In particular, it compares the analyses of vehicle transaxle noise under run-up and coast-down conditions using spatial transformation of sound field (STSF) and Helmholtz equation least-squares (HELS) based NAH. It also demonstrates an application of HELS to visualizing brake squeals and compares its advantages and disadvantages to those of a laser vibrometer.
Vibration response of buildings to rail transit groundborne vibration
Authors: Phillips James
Published: October 2013

The FTA guidelines for detailed analysis and prediction of groundborne noise and vibration generated by rail transit systems are based on established empirical methods. The procedures for the measurement of vehicle/track system source strength and the attenuation of vibration as it propagates with distance through the ground are generally accepted practice at this time. However, characterization of the building response is open to debate, due in part to the wide array of building construction encountered adjacent to transit systems. Numerous measurements that have been obtained in a variety of building construction types are presented and preliminary conclusions are drawn regarding the responses of several common building types to rail transit groundborne vibration.
Sparse channel estimation for underwater acoustic communication channels
Authors: Song Aijun , Badiey Mohsen
Published: October 2013

In underwater communication channels, acoustic arrivals often form a cluster structure. The number of significant taps is limited although the length of the channel can be very large. As shown in the previously reported research, channel estimation can benefit the performance of the coherent communication and promise to support high data rate and reliable underwater acoustic communication. Since underwater communication channels are sparse in time domain, channel-estimation algorithms can have lower complexity and higher accuracy by exploiting the sparse property. Various sparse channel estimation techniques, including threshold recursive least-squares (RLS), matching-pursuit, and on-off keying detection algorithms, are investigated in underwater communication channels. Their effectiveness and complexity are compared using communication data measured from the Kauai experiment, July 2003. Their impacts on the communication performance are also presented.
Wavefront control by wave number domain focusing
Authors: Choi Joung-Woo , Jang Ji-Ho , Kim Yang-Hann
Published: October 2013

This study introduces a novel method that can manipulate propagating direction of wavefronts within a selected region using source array. The idea of the proposed method stems from a method of acoustic contrast maximization, which has been used to focus sound energy within a zone of interest. This paper attempts to focus sound energy in the wave number domain, so that the sound energy of a selected region is concentrated on a desired wave number area. This makes it possible to generate a plane wave that propagates to a desired direction. The simple pure-tone case is considered to express the idea in the wave number domain; then, the method is extended to more general case, where an excitation signal has a broadband spectrum. Numerical and experimental results obtained in various conditions certainly validate that the direction of the wavefront can be manipulated for some finite region in space. [Work supported by the BK21 project initiated by Ministry of Education and Human Resources Development of Korea.]
Focalization in environments with stochastic sediment uncertainties
Authors: Baer Ralph N. , Collins Michael D.
Published: October 2013

Focalization has recently been generalized to problems involving internal waves [R. N. Baer and M. D. Collins, J. Acoust. Soc. Am. 115, 2550 (2004)]. Although there are basic differences between this stochastic focalization problem and the deterministic focalization problems that were considered previously, the essential concept of a parameter hierarchy applies to both problems. Stochastic focalization is currently being implemented and tested for problems involving uncertainties in the sediment. This source localization problem is of practical importance since there are often significant uncertainties in sediments. Like internal waves, ocean sediments can be highly complex. Although it is often desirable to invert for ocean bottom parameters, this is not always practical when source localization is the main goal. Due to the parameter hierarchy, it is often possible to determine the correct source position without determining the correct sediment parameters. [Work supported by the ONR.]
Analysis and control of air compressor noise
Authors: Song Wonjoon , Pattnaik Shrikant , Zhao Wancheng , Bapat Milind , Kim Hyunsoo
Published: October 2013

Study of noise characteristics of a small air compressor used in typical construction sites was conducted to develop possible noise reduction strategies of the compressor as a student group project. Operating the compressor at the steady-state condition, the sound power of the tool was measured by using a 10-microphone measurement method in the semianechoic chamber. The SPL spectrum from each of the microphones was carefully compared and studied. A sound intensity measurement was conducted to identify major noise sources of the compressor, which identified the electric motor and inlet air pulsation as the major noise sources. Several possible measures were applied for noise reduction of the compressor, which included a newly designed intake muffler, an absorptive liner around the motor area and an improved mounting. The effect of each of these measures was measured one by one first, then in combinations. The resulting changes were measured and discussed in terms of the noise characteristics and noise levels.
Time synchronization and geoacoustic inversion using baleen whale sounds
Authors: Thode Aaron , Gerstoft Peter , Stokes Dale , Noad Mike , Burgess William , Cato Doug
Published: October 2013

In 1996 matched-field processing (MFP) and geoacoustic inversion methods were used to invert for range, depth, and source levels of blue whale vocalizations. [A. M. Thode, G. L. D’Spain, and W. A. Kuperman, J. Acoust. Soc. Am. 107, 1286–1300 (2000)]. Humpback whales also produce broadband sequences of sounds that contain significant energy between 50 Hz to over 1 kHz. In Oct. 2003 and 2004 samples of humpback whale song were collected on vertical and titled arrays in 24-m-deep water in conjunction with the Humpback Acoustic Research Collaboration (HARC). The arrays consisted of autonomous recorders attached to a rope, and were time synchronized by extending standard geoacoustic inversion methods to invert for clock offset as well as whale location. The diffuse ambient noise background field was then used to correct for subsequent clock drift. Independent measurements of the local bathymetry and transmission loss were also obtained in the area. Preliminary results are presented for geoacoustic inversions of the ocean floor composition and humpback whale locations and source levels. [Work supported by ONR Ocean Acoustic Entry Level Faculty Award and Marine Mammals Program.]
The articulatory and acoustical characteristics of the ‘‘apical vowels’’ in Beijing Mandarin
Authors: Lee Wai-Sum
Published: October 2013

The study investigates the articulatory and acoustical characteristics of the two so-called ‘‘apical vowels’’ in Beijing Mandarin, which have been referred to as ‘‘apical anterior vowel’’ and ‘‘apical posterior vowel’’ by the linguists in China. The ‘‘apical posterior vowel’’ has also been described as a retroflex. The results of an EMA (electromagnetic articulograph) analysis show that both vowels are apical, with the tip of tongue approaching the alveolar region for the ‘‘anterior vowel’’ and the postalveolar region for the ‘‘posterior vowel.’’ The ‘‘posterior vowel’’ is pharyngealized, as the body of tongue in particular the posterodorsal portion is pulled backward toward the pharynx. Acoustical data obtained using the CSL4400 speech analysis software show that the two ‘‘apical vowels’’ have similar F1 value. The F2 value is slightly larger for the ‘‘posterior vowel’’ than ‘‘anterior vowel.’’ Thus, the correlation between a larger F2 and the advanced tongue position is not applicable to these ‘‘apical vowels.’’ The main difference between the two ‘‘apical vowels’’ is in F3, where the value is much smaller for the ‘‘posterior vowel’’ than ‘‘anterior vowel.’’ It is assumed that the smaller F3 value for the ‘‘posterior vowel’’ is due to pharyngealization.
Guide source depth and range translation for robust matched field processing (MFP)
Authors: Zurk Lisa M.
Published: October 2013

The solutions to the modal wave equation have the well-known property of orthonormality. Previous work has suggested that mode functions also satisfy an approximate orthonormality condition formed when the product of the mode functions and their spatial derivatives are integrated over the water column. In the new orthogonality expression, unity is obtained when the integrand contains eigenfunctions from sequentially propagating modes (i.e., m=n+1), not alike modes (m=n). This relationship can be exploited in matched field processing (MFP) with a guide source to derive the replica vectors. In standard MFP formulation, the guide source measurement only provides a transfer function at the guide location. Using the new formulation, it is shown that the MFP peak shifts to a frequency-dependent depth that differs from the guide depth. This depth-shifting operation enables the generation of replica vectors for a range of target depths from a single broadband guide source. The operation does not require environmental information, and is thus robust to uncertainty. In this talk the theoretical background is developed and simulation results are presented for various geometries. In addition, recent extensions of this work to include combined range and depth shifting using the invariance principle are presented and discussed.
Achieving acoustical performance with fire safe products
Authors: Fritz Thomas
Published: October 2013

Recent serious fires in North and South America have pointed out potential problems with attempts to improve acoustical performance in building spaces at the expense of using acoustical treatments that may have poor performance in fire situations. Foam plastic products, sometimes not designed for exposed use in buildings, can ignite quickly and spread fire rapidly throughout a building space, resulting in fire victims being trapped within the building or not being afforded the needed safe egress time. There are ways of achieving equivalent and even superior acoustical performance without sacrificing fire safety. Acoustical products are available which can add comparable or superior acoustical treatment without the fire hazard associated with exposed foam plastic materials. This presentation is a review of the U.S. code requirements of interior finish materials, the various types of fire tests that are applied to these products, and a discussion of the achievable fire and acoustical performance.
Performance comparison of compact cylindrical and spherical windscreens
Authors: Shams Qamar A. , Zuckerwar Allan J. , Sealey Bradley S.
Published: October 2013

An improved and compact windscreen was conceived for a microphone of a type used outdoors to detect atmospheric infrasound from a variety of natural and artificial sources. This cylindrically shaped compact windscreen, made of closed-cell polyurethane foam, had dimensions of 0.0762 m i.d. ×0.2286 m height ×0.0127 m wall (3×9×0.5 in.). The low acoustic impedance of the foam showed a transmission coefficient near unity. The same closed-cell polyurethane foam was used to fabricate a spherical windscreen of 0.254 m (10 in.) diameter with 0.0127-m (0.5 in.) wall thickness. In this paper the effectiveness of cylindrical and spherical windscreens is evaluated using a low-speed wind tunnel facility that enables controlled and repeatable experiments. Wind noise levels are characterized for both windscreens as a function of frequency and mean wind velocity.
Where should we eat?: Predator and prey spatial relationships in the Antarctic krill ecosystem
Authors: Warren Joseph D. , Santora Jarrod , Demer David
Published: October 2013

Acoustic surveys of the distribution and abundance of Antarctic krill were conducted by two different vessels in February 2005 in the near-shore waters of Livingston Island, Antarctica. Multiple frequency acoustic backscatter, video observations, and net tow data were used to identify the acoustic scatterers and to estimate the abundance of krill. Hydrographic, meteorologic, and net tow data were used to examine physical forcing functions affecting the spatial distribution of krill. In addition, the behavior and distribution of several krill predators (penguins, petrels, and whales) were also measured during the survey to explore biological factors affecting the krill ecosystem. Both horizontal and vertical patterns of habitat utilization by prey (krill) and these predators were examined. The survey was interrupted midway through by a large storm event that limited ship-based observations for a day, but provided a picture of the ecosystem before and after the disturbance. [Work supported by the NSF Office of Polar Programs and NOAA.]
Does clear speech enhance the voice onset time contrast in Croatian and English?
Authors: Smiljanic Rajka , Bradlow Ann
Published: October 2013

This study investigates the effect of intelligibility-enhancing clear speech on voice onset time (VOT) in two languages with different phonetic realizations of a two-way voicing contrast. Specifically, it was explored whether the contrasts between prevoiced and short-lag categories in Croatian and short-lag and long-lag categories in English are enhanced along the VOT dimension in clear speech. Word-initial stops in words embedded in sentences read by native speakers of each language in conversational and clear speaking styles were examined. The results revealed that in English, the long-lag category (i.e., voiceless) extended somewhat in the positive VOT direction (longer aspiration), and in Croatian, the prevoiced category (i.e., voiced) extended somewhat in the negative VOT direction (longer prevoicing) in clear speech. However, in both languages, the short-lag tokens (i.e., voiced in English, voiceless in Croatian) were unchanged in clear versus conversational speech. Overall, then, the distance between the two voicing categories was rather stable across the two speaking styles in both languages. These results suggest that VOT is not a dimension of voicing category contrast enhancement. Rather, the language-specific pronunciation norms along this dimension are maintained in clear and conversational speech.
Radiation properties and sound quality characteristics of refrigerator noise
Authors: Jeon Jin Yong , Jeong Jeong Ho , You Jin
Published: October 2013

The characteristics of refrigerator noise in an anechoic chamber and in an actual environment were investigated. In order to predict the noise propagation in real apartment house, room acoustic simulations and measurements using different types of refrigerators were conducted. The sound-pressure level of the refrigerator noise in the real living room was much higher than in the anechoic chamber. In addition, an allowable sound-pressure level for refrigerator noise was determined by auditory experiments. For the stimuli of auditory experiments, the dry source of refrigerator noise was presented using a loud speaker at the position of the refrigerator. When the result of the subjective evaluation was at the level 2 (the noise rarely aware but comfortable), in which sound pressure level was about 25 dB(A), 95% of people were satisfied with the refrigerator noise. A semantic differential test using various adjectives was also conducted to evaluate the sound quality of refrigerator noise.
Echoic functional class formation by a bottlenose dolphin
Authors: Kastak David , Schusterman Ronald
Published: October 2013

A bottlenose dolphin was trained to perform separate two-choice simple discrimination tasks using echolocation and vision. The targets were air-filled shapes constructed from PVC pipe. Targets varied in length and width but not depth, and were separated into classes of letters and numbers. Target echoes were measured, and classes were set up so that they could not be grouped on the basis of perceptual similarities between class members. The subject showed successful learning set formation (win-stay, lose-shift) in visual and echoic discrimination reversals consisting of specific target pairings. The subject also successfully grouped targets into classes as shown by performance in a discrimination reversal procedure involving sets of targets rather than individual pairings. The subject was unable to group the same targets using vision instead of echolocation. No evidence of bimodal performance enhancement or immediate cross-modal transfer was shown. The results suggest that dolphins can arbitrarily classify dissimilar targets using echolocation, but that performance can be independent of visual information. Successful cross-modal class formation likely results from high levels of experience associating echoic and visual stimuli, therefore is more likely to be shown in the context of a conditional discrimination rather than a simple discrimination task. [Work supported by ONR.]
Effect of discharge duct geometry on centrifugal fan performance and noise emission
Authors: Nelson David A. , Butrymowicz William , Thomas Christopher
Published: October 2013

Non-ideal inlet and discharge duct geometries can cause significant changes to both the aerodynamic performance (‘‘fan curve’’) and specific sound power emission of a fan. A proper understanding of actual installed performance, as well as a good estimate of the system backpressure curve, is critical to achieving flow and acoustic goals as well as other criteria such as power consumption, mass and volume. To this end a battery of ISO 10302 tests was performed on a blower assembly which supports the Advanced Animal Habitat, being developed by ORBITEC for deployment on the International Space Station. The blower assembly consists of (4) identical centrifugal fans that, amongst themselves and across two prototypes, incorporated several discharge geometries. The inlet geometries were identical in all cases. Thus by comparing the dimensionless pressure-flow and noise emission characteristics across the cases, significant insight into the nature and potential magnitude of these effects is gained.
Sound quality in the assessment of noise annoyance in air-conditioned buildings
Authors: Cirillo Ettore , Martellotta Francesco
Published: October 2013

The results of the search for a new parameter to be used in describing the subjective sensation of noise annoyance in air-conditioned offices are presented. The typical analysis technique in this field is to correlate objective parameters with subjective ratings by means of parametric statistics. A common procedure to find better objective descriptors of the subjective sensation is to combine different parameters. Previous studies used to combine a parameter measuring the continuous noise level with one measuring the fluctuations of noise levels. However, this approach neglected the effect that the quality of the noise produces on subjects. As the RC Mark II procedure for rating the noise of HVAC systems in buildings introduced the ‘‘Quality Assessment Index’’ QAI, which provides a measure of the spectral imbalance of a noise, the combination of this parameter with the RC criterion number (which only measures noise level) was proposed. A suitable combination coefficient was proposed based on the results of a noise environment survey involving both objective and subjective measurements. A second survey confirmed that the combination of these indices may significantly contribute to better describe noise annoyance.
A Bayesian approach to incorporating maximum entropy-derived signal parameter statistics into the receiver operating characteristic (ROC) curves
Authors: Culver R. Lee , Sibul Leon H. , Bradley David L. , Ballard Jeffrey A. , Camin H. John
Published: October 2013

Our goal is to develop a probabilistic sonar performance prediction methodology that can make use of limited knowledge of random or uncertain environment, target, and sonar system parameters, but does not make unwarranted assumptions. The maximum entropy method (MEM) can be used to construct probability density functions (pdfs) for relevant environmental and source parameters, and an ocean acoustic propagation model can use those pdfs to predict the variability of received signal parameter. At this point, the MEM can be used once again to produce signal parameter pdfs. A Bayesian framework allows these pdfs to be incorporated into the signal processor to produce ROC curves in which, for example, the signal-to-noise ratio (SNR) is a random variable for which a pdf has been calculated. One output of such a processor could be a range-dependent probability of detection for fixed probability of false alarm, which would be more useful than the conventional range of the day that is still in use in some areas. [Work supported by ONR Code 321US.]
Plumbing noise in multifamily dwellings: 50 years and counting
Authors: LoVerde John J. , Dong David W.
Published: October 2013

Historically, plumbing sound was only of concern in luxury buildings and plumbing noise was rarely addressed explicitly in building codes or design guidelines. The last couple of decades have seen marked increases in population density, occupant expectations and sensitivity to noise, and the number of noise-related lawsuits. These demographic factors have considerably increased the importance of adequately addressing plumbing noise in multifamily projects, as shown by the increasing number of published guidelines (such as in the latest ASHRAE Handbook). Over the course of our firm’s history, we have attempted to determine the relationship between the sound level from plumbing systems and the acceptability to the occupants. Our current criteria for plumbing noise and the reasoning behind them is discussed, including test cases and lawsuits, as well as the materials and methods available to meet those criteria, and their impact on the design of multifamily projects.
Syllable and phrase structure effects on consonant sequence timing
Authors: Byrd Dani , Choi Susie
Published: October 2013

Both syllable and phrasal structure are known to influence articulatory timing in consonant sequences. For example, onset clusters have been reported as less overlapped and more stable in their intergestural timing than coda clusters [e.g., Byrd, J. Phonetics (1996)]. Also, consonants spanning a phrasal boundary have been observed to be less overlapped than those spanning only a word boundary [Byrd et al., LabPhon (2003)]. However, interactions between these two types of structure are less well understood; for example, it is unclear whether the intergestural timing of word-onset clusters will be perturbed at phrase boundaries, though such perturbations have been predicted [Byrd and Saltzman (2003)]. An articulatory (EMA) investigation of /s/+stop sequences produced by three speakers in a variety of syllable and phrasal positions will present kinematic data on these structural influences. Preliminary data from one speaker indicate that word-onset consonant clusters are more sensitive to prosodic context than segmentally identical coda clusters, having less overlap at successively larger boundaries. Further, while coda and onset clusters do not show a mean difference in overlap for this speaker, onset clusters do exhibit more timing stability within each phrasal context compared to corresponding coda clusters. [Work supported by NIH.]
Observation of Floquet-Bloch States on the Surface of a Topological Insulator
Authors: Wang Y. H. , Steinberg H. , Jarillo-Herrero P. , Gedik N.
Published: October 2013

Topological Replicas

When a periodic perturbation couples strongly to electrons in a solid, replicas of the original electronic levels are predicted to develop at certain energies—the so-called Floquet-Bloch states. Such conditions can be achieved by shining light on a solid, but the effect is challenging to observe.

Wang
et al.

(p.
453
) used time- and angle-resolved photoemission spectroscopy to photoexcite Bi
2
Se
3
and observe its dispersion at various delay times. The replicas were seen at expected energy shifts, along with the gaps predicted to occur at the new energy-level crossings caused by the appearance of the replicas. Because Bi
2
Se
3
is a topological insulator, the breaking of the time-reversal symmetry caused by circularly polarized light resulted in the appearance of an energy gap at the Dirac point, indicating an interesting route toward manipulating electronic states in such materials.
Atypical Combinations and Scientific Impact
Authors: Uzzi Brian , Mukherjee Satyam , Stringer Michael , Jones Ben
Published: October 2013

Making an Impact

How big a role do unconventional combinations of existing knowledge play in the impact of a scientific paper? To examine this question,

Uzzi
et al.

(p.
468
) studied 17.9 million research articles across five decades of the Web of Science, the largest repository of scientific research. Scientific work typically appeared to draw on highly conventional, familiar mixtures of knowledge. The highest-impact papers were not the ones that had the greatest novelty, but had a combination of novelty and otherwise conventional combinations of prior work.
From Few to Many: Observing the Formation of a Fermi Sea One Atom at a Time
Authors: Wenz A. N. , Zürn G. , Murmann S. , Brouzos I. , Lompe T. , Jochim S.
Published: October 2013

Not Very Many

In physics, the behavior of a system sometimes becomes easier to grasp when the number of particles is large and statistics begin to matter, but knowing how large the system needs to be for that to happen is a challenging computational problem.

Wenz
et al.

(p.
457
) used a one-dimensional trapped gas of
6
Li atoms to study this crossover from few to many. To simplify the problem, they worked with one “impurity” atom that was in a state unlike the other—“majority”—atoms. For weak and intermediate interactions, the system approached the many-body limit with as few as four majority atoms.
Blooms Bite the Hand That Feeds Them
Authors: Paerl Hans W. , Otten Timothy G.
Published: October 2013

A positive feedback exists between eutrophication and the global proliferation of toxin-producing cyanobacterial blooms.
Ancient DNA Links Native Americans With Europe
Authors: Balter Michael
Published: October 2013

Ancient DNA from a Siberian boy offers surprising clues to the identity of the first Americans.
U.S. Shutdown Ends, but Not Budget Anxiety
Authors: Mervis Jeffrey
Published: October 2013

The U.S. government shutdown is over, but anxiety over future spending levels for science continues.
Efficient Activation of Human T Cells of Both CD4 and CD8 Subsets by Urease-Deficient Recombinant Mycobacterium bovis BCG That Produced a Heat Shock Protein 70-M. tuberculosis-Derived Major Membrane Protein II Fusion Protein
Authors: Mukai Tetsu , Tsukamoto Yumiko , Maeda Yumi , Tamura Toshiki , Makino Masahiko
Published: October 2013

For the purpose of obtainingMycobacterium bovisbacillus Calmette-Guérin (BCG) capable of activating human naive T cells, urease-deficient BCG expressing a fusion protein composed ofMycobacterium tuberculosis-derived major membrane protein II (MMP-II) and heat shock protein 70 (HSP70) of BCG (BCG-DHTM) was produced. BCG-DHTM secreted the HSP70-MMP-II fusion protein and effectively activated human monocyte-derived dendritic cells (DCs) by inducing phenotypic changes and enhanced cytokine production. BCG-DHTM-infected DCs activated naive T cells of both CD4 and naive CD8 subsets, in an antigen (Ag)-dependent manner. The T cell activation induced by BCG-DHTM was inhibited by the pretreatment of DCs with chloroquine. The naive CD8+T cell activation was mediated by the transporter associated with antigen presentation (TAP) and the proteosome-dependent cytosolic cross-priming pathway. Memory CD8+T cells and perforin-producing effector CD8+T cells were efficiently produced from the naive T cell population by BCG-DHTM stimulation. Single primary infection with BCG-DHTM in C57BL/6 mice efficiently produced T cells responsive toin vitrosecondary stimulation with HSP70, MMP-II, andM. tuberculosis-derived cytosolic protein and inhibited the multiplication of subsequently aerosol-challengedM. tuberculosismore efficiently than did vector control BCG. These results indicate that the introduction of MMP-II and HSP70 into urease-deficient BCG may be useful for improving BCG for control of tuberculosis.
Comparison of Sputum and Nasopharyngeal Aspirate Samples and of the PCR Gene Targets
lytA
and Spn9802 for Quantitative PCR for Rapid Detection of Pneumococcal Pneumonia
Authors: Strålin Kristoffer , Herrmann Björn , Abdeldaim Guma , Olcén Per , Holmberg Hans , Mölling Paula
Published: October 2013

We aimed to compare sputum and nasopharyngeal aspirate (NpA) samples and the PCR gene targets
lytA
and Spn9802 in quantitative PCR (qPCR) assays for rapid detection of pneumococcal etiology in community-acquired pneumonia (CAP). Seventy-eight adult patients hospitalized for radiologically confirmed CAP had both good-quality sputum and NpA specimens collected at admission. These samples were subjected to
lytA
qPCR and Spn9802 qPCR assays with analytical times of <3 h. Thirty-two patients had CAP with a pneumococcal etiology, according to conventional diagnostic criteria. The following qPCR positivity rates were noted in CAP cases with and without pneumococcal etiology: 96% and 15% (sputum
lytA
assay), 96% and 17% (sputum Spn9802 assay), 81% and 11% (NpA
lytA
assay), and 81% and 20% (NpA Spn9802 assay), respectively. The mean
lytA
and Spn9802 DNA levels were significantly higher in qPCR-positive sputum samples from cases with pneumococcal etiology than in qPCR-positive sputum samples from CAP cases without pneumococcal etiology or qPCR-positive NpA samples from cases with pneumococcal etiology (
P
< 0.02 for all comparisons). For detection of pneumococcal etiology, receiver operating characteristic curve analysis showed that sputum specimens were superior to NpA specimens as the sample type (
P
< 0.02 for both gene targets) and
lytA
tended to be superior to Spn9802 as the gene target. The best-performing test, the sputum
lytA
qPCR assay, showed high sensitivity (94%) and specificity (96%) with a cutoff value of 10
5
DNA copies/ml. In CAP patients with good sputum production, this test has great potential to be used for the rapid detection of pneumococcal etiology and to target penicillin therapy.
Frequency of Susceptibility Testing for Patients with Persistent Methicillin-Resistant Staphylococcus aureus Bacteremia
Authors: Giltner Carmen L. , Kelesidis Theodoros , Hindler Janet A. , Bobenchik April M. , Humphries Romney M.
Published: October 2013

Currently, no standards exist for determining the optimal frequency of repeat antimicrobial susceptibility testing (AST) when an organism is recurrently isolated from the same specimen source. Although testing every 2 to 5 days is thought sufficient, we present three cases of methicillin-resistant
Staphylococcus aureus
(MRSA) bacteremia where current laboratory protocol for repeating AST every 5 days was inadequate to identify resistant organisms.
Rapid Identification of Staphylococcus aureus Directly from Bactec Blood Culture Broth by the BinaxNOW S. aureus Test
Authors: Qian Qinfang , Eichelberger Karen , Kirby James E.
Published: October 2013

The BinaxNOW
Staphylococcus aureus
testing showed sensitivity, specificity, and positive and negative predicative values of 97.6%, 100%, 100%, and 98.4%, respectively, for identification of
S. aureus
from Bactec blood culture broth. Importantly, the test performed equally well on aerobic and anaerobic culture broth.
Use of Micafungin as a Surrogate Marker To Predict Susceptibility and Resistance to Caspofungin among 3,764 Clinical Isolates of Candida by Use of CLSI Methods and Interpretive Criteria
Authors: Pfaller Michael A. , Messer Shawn A. , Diekema Daniel J. , Jones Ronald N. , Castanheira Mariana
Published: October 2013

Due to unacceptably high interlaboratory variation in caspofungin MIC values, we evaluated the use of micafungin as a surrogate marker to predict the susceptibility ofCandidaspp. to caspofungin using reference methods and species-specific interpretive criteria. The MIC results for 3,764 strains ofCandida(eight species), including 73 strains withfksmutations, were used. Caspofungin MIC values and species-specific interpretive criteria were compared with those of micafungin to determine the percent categorical agreement (%CA) and very major error (VME), major error (ME), and minor error rates as well as their ability to detectfksmutant strains ofCandida albicans(11 mutants),Candida tropicalis(4 mutants),Candida krusei(3 mutants), andCandida glabrata(55 mutants). Overall, the %CA was 98.8% (0.2% VMEs and MEs, 0.8% minor errors) using micafungin as the surrogate marker. Among the 60 isolates ofC. albicans(9 isolates),C. tropicalis(5 isolates),C. krusei(2 isolates), andC. glabrata(44 isolates) that were nonsusceptible (either intermediate or resistant) to both caspofungin and micafungin, 54 (90.0%) contained a mutation infks1orfks2. An additional 10C. glabratamutants, twoC. albicansmutants, and one mutant each ofC. tropicalisandC. kruseiwere classified as susceptible to both antifungal agents. Using the epidemiological cutoff values (ECVs) of 0.12 μg/ml for caspofungin and 0.03 μg/ml for micafungin to differentiate wild-type (WT) from non-WT strains ofC. glabrata, 80% of theC. glabratamutants were non-WT for both agents (96% concordance). Micafungin may serve as an acceptable surrogate marker for the prediction of susceptibility and resistance ofCandidato caspofungin.
Monitoring of Patients Supported by Extracorporeal Membrane Oxygenation for Systemic Infections by Broad-Range rRNA Gene PCR Amplification and Sequence Analysis
Authors: Orszag Peter , Disqué Claudia , Keim Sonja , Lorenz Michael G. , Wiesner Olaf , Hadem Johannes , Stiesch Meike , Haverich Axel , Kühn Christian
Published: October 2013

The rRNA gene PCR and sequencing test, SepsiTest, was compared with blood culture (BC) regarding the diagnosis of pathogens in 160 blood samples drawn from 28 patients during extracorporeal membrane oxygenation. With 45% of positive samples, SepsiTest was 13 to 75 h faster than BC. SepsiTest indicated bacteremias in 25% of patients who were BC negative.
Recent Advances in Detection of Plasmodium ovale: Implications of Separation into the Two Species Plasmodium ovale wallikeri and Plasmodium ovale curtisi
Authors: Fuehrer Hans-Peter , Noedl Harald
Published: October 2013

Recent molecular studies indicate that
Plasmodium ovale
malaria is caused by two closely related species of protozoan parasites, thereby imposing new challenges for detection and species differentiation. This minireview explores the potential value of innovative methods for the molecular diagnosis of malaria with a strong emphasis on the discrimination and genotyping of
P. ovale wallikeri
and
P. ovale curtisi
as well as tools for the simultaneous detection of
P. ovale
sp. An update for the widely used NP-1993 to NP-2005 (SSU rRNA) protocols for all human malaria parasites is discussed.
A Novel Subnucleocapsid Nanoplatform for Mucosal Vaccination against Influenza Virus That Targets the Ectodomain of Matrix Protein 2
Authors: Hervé Pierre-Louis , Raliou Mariam , Bourdieu Christiane , Dubuquoy Catherine , Petit-Camurdan Agnès , Bertho Nicolas , Eléouët Jean-François , Chevalier Christophe , Riffault Sabine
Published: October 2013

In this study, subnucleocapsid nanorings formed by the recombinant nucleoprotein (N) of the respiratory syncytial virus were evaluated as a platform to anchor heterologous antigens. The ectodomain of the influenza virus A matrix protein 2 (M2e) is highly conserved and elicits protective antibodies when it is linked to an immunogenic carrier, making it a promising target to develop universal influenza vaccines. In this context, one or three M2e copies were genetically linked to the C terminus of N to produce N-M2e and N-3M2e chimeric recombinant nanorings. Mice were immunized intranasally with N-M2e or N-3M2e or with M2e or 3M2e control peptides. N-3M2e-vaccinated mice showed the strongest mucosal and systemic antibody responses. These mice presented a reduced viral load and minor weight loss, and all survived upon challenge with influenza virus A/PR8/34 (H1N1) (PR8). We compared the intranasal route to the subcutaneous route of N-3M2e immunization. Only the intranasal route induced a strong local IgA response and led to the protection of mice upon challenge. Finally, we demonstrated that the induction of anti-M2e antibodies by N-3M2e is not impaired by preexisting anti-N immunity. Overall, these results show that the N nanoring is a potent carrier for mucosal delivery of vaccinal antigens.
Adaptive Mutations in the Nuclear Export Protein of Human-Derived H5N1 Strains Facilitate a Polymerase Activity-Enhancing Conformation
Authors: Reuther Peter , Giese Sebastian , Götz Veronika , Kilb Normann , Mänz Benjamin , Brunotte Linda , Schwemmle Martin
Published: October 2013

The nuclear export protein (NEP) (NS2) of the highly pathogenic human-derived H5N1 strain A/Thailand/1(KAN-1)/2004 with the adaptive mutation M16I greatly enhances the polymerase activity in human cells in a concentration-dependent manner. While low NEP levels enhance the polymerase activity, high levels are inhibitory. To gain insights into the underlying mechanism, we analyzed the effect of NEP deletion mutants on polymerase activity after reconstitution in human cells. This revealed that the polymerase-enhancing function of NEP resides in the C-terminal moiety and that removal of the last three amino acids completely abrogates this activity. Moreover, compared to full-length NEP, the C-terminal moiety alone exhibited significantly higher activity and seemed to be deregulated, since even the highest concentration did not result in an inhibition of polymerase activity. To determine transient interactions between the N- and C-terminal domains in
cis
, we fused both ends of NEP to a split click beetle luciferase and performed fragment complementation assays. With decreasing temperature, increased luciferase activity was observed, suggesting that intramolecular binding between the C- and N-terminal domains is preferentially stabilized at low temperatures. This stabilizing effect was significantly reduced with the adaptive mutation M16I or a combination of adaptive mutations (M16I, Y41C, and E75G), which further increased polymerase activity also at 34°C. We therefore propose a model in which the N-terminal moiety of NEP exerts an inhibitory function by back-folding to the C-terminal domain. In this model, adaptive mutations in NEP decrease binding between the C- and N-terminal domains, thereby allowing the protein to “open up” and become active already at a low temperature.