bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of relief on the amplitude and velocity of acoustic surface waves as applied to the tasks of passive seismic prospecting
Authors: Zhostkov Ruslan A.
Published: June 2021

Today, in geophysics, passive technologies of surface-wave tomography and methods that analyze the amplitude characteristics of surface waves are widely used. Unfortunately, the issues of taking into account the influence of the relief on the results of these methods have not yet been given due attention. The existing solutions are poorly corresponding to the real tasks of geophysics. Numerical models have been created for the study of surface waves. Their correctness is confirmed by comparison with the results of laboratory experiments. A study of the scattering of surface waves on the features of the relief of various shapes and sizes, including for the seabed and ice-covered water, has been carried out. It is shown that the effect of the relief at certain parameters can change the structure of the field more strongly than local inhomogeneities of the medium. A positive relief can lead to a significant change in the effective velocity of surface waves due to the effect of splitting of these waves discovered both by numerical simulation and laboratory experiment. [This work was financially supported by the Russian Foundation for Basic Research (Project No. 18-05-70034).]
Excellence of acoustics in India—Its heritage and recent research
Authors: Agrawal Shyam S.
Published: June 2021

Acoustics research and its applications have been an age-old tradition in India. In ancient times it has marvelous examples of achievement particularly in the areas of production of sounds, vocal recitations, musical instruments and in architectural acoustics. Rules for production of sounds, chanting Vedas, and methods of playing instruments were well designed. Similarly, the forts and temples were designed with great mathematical accuracy from the acoustics points of view. In recent times acoustic research have been pursued in several areas in R&D laboratories, educational institutions and in industries. Some of these include research in physical acoustics, ultrasonic, non-linear acoustics, transducers, material characterization, NDT, etc. Underwater and sonar acoustics; Speech processing and hearing, acoustic phonetics and development of Indian speech and language resources, etc.; Study on Indian classical music and musical instruments; Environmental and Noise control including industrial noise control; vibro- and aero-acoustics for acoustic protection systems; Building and architectural acoustics are getting great attention. Many projects are carried out with international collaboration. The standards in acoustic measurements, calibration are maintained and updated at the National level. AI and digital technologies play a vital role in development of Acoustical systems. This paper describes technologies and status of research in acoustics in India.
Acoustic research at the National University of Singapore
Authors: Lee Heow Pueh
Published: June 2021

Noise pollution is a major problem in many major cities in particular a small island state like Singapore with residential buildings very close to the major trunk roads and expressways. There are therefore increased interest in designs and solutions that will contribute to better sonic ambience. In this presentation, I will focus on the recent research and investigation in related to sonic crystals, acoustic metamaterials, noise barriers, and soundscape. The focus on sonic crystal research is on the use of sonic crystals in the form of sonic windows and sonic cage that would provide noise mitigation in addition to natural ventilation and day light. The design would also include the incorporation of Helmholtz’s resonators, labyrinth and micro-perforated features into the sonic crystal structures. The focus on acoustic metamaterials would be on ventilated acoustic meta-structures incorporating Helmholtz’s resonators and labyrinth or coiled-up space features. For soundscape research, a novel calibration method has been put forward for making the typical smartphone to be accurate enough as a sound level meter for the measurement of environmental noise. Some studies in terms of cabin noise of subway systems, aircraft cabins, high speed trains would be presented.
Mobile voice recording and analysis: Uncertainty and reproducibility
Authors: Hunter Eric J.
Published: June 2021

Mobile voice recording has been a staple of voice research, providing an authentic representation of speech outside a controlled environment; however, mobile recordings increase uncertainty with potential environmental sound contamination, as well as speech production differences due to variations in environment, purpose, or communication partner. Several studies will be reviewed to give context to uncertainty and reproducibility issues to be considered when conducting mobile voice recording.
Individual differences in speech perception: Evidence for gradiency in the face of category-driven perceptual warping
Authors: Kapnoula Efthymia C. , McMurray Bob
Published: June 2021

In contrast to the long-running debates around universally categorical vs. gradient speech perception, we find individual differences in listeners' sensitivity to subtle acoustic differences between speech sounds (within and between phoneme categories). Here, we used an EEG measure of listeners' early perceptual encoding of a primary acoustic cue and found that categorical listeners showed stronger perceptual warping around the boundary, even as sensitivity to within-category differences was present across the board.
Green's functions extraction between ships of opportunity using a vertical array
Authors: Byun Gihoon , Song Hee-Chun
Published: June 2021

This work describes a method for extracting the time-domain Green’s function between two ships in a shallow-water environment. First, the individual Green’s functions from each ship are estimated along the vertical receiver array using blind deconvolution. Then, the Green’s function between two ships is obtained simply by either correlation or convolution of the individual Green’s functions, depending on the array position with respect to the ships. Simulation and experimental results are presented and discussed to demonstrate the feasibility of extracting the Green’s functions between ships radiating random broadband noise (100–500 Hz), using a 56.25 m long vertical array in about 100-m deep shallow water.
Modeling time reversal focusing amplitudes in a reverberation chamber using a modal summation approach
Authors: Patchett Brian D. , Anderson Brian E. , Kingsley Adam D.
Published: June 2021

Time reversal (TR) is a signal processing technique often used to generate focusing at selected positions within reverberant environments. This study looks at the effect of the location of the focusing, with respect to the room wall boundaries, on the amplitude of the focusing and the uniformity of this amplitude at various room locations. A numerical model based on the summation of room modes was created to simulated the TR process in a large reverberation chamber. This model returned results that showed the peak amplitude of the focusing is quite uniform, and that there is also a notable increase in amplitude for each additional surface that is adjacent to the modeled focal location. With spatial uniformity of focusing within the room and uniform increases when the focusing is near adjacent walls. An experiment was conducted that verified the numerical findings, resulting in the confirmation of both the uniformity and uniform increases as the focusing position is moved near an adjacent wall.
Experiences on voice assessment and voice intervention programs implemented remotely among college professors
Authors: Cantor-Cutiva Lady Catherine
Published: June 2021

This is a meta-analysis of two longitudinal studies and one cross-sectional study with the aim of analyzing the response rate and adherence to voice programs implemented remotely. In the cross-sectional study, we collected responses of around 150 college professors, for 2 weeks, by means of a Google form. Around 30% of participants reported voice symptoms. In the longitudinal studies, we recruited around 50 college professors, who were followed between 15 days and 5 weeks. In the first study, college professors met (in Zoom meetings) with a Speech-language pathologist every day to fill-in a short questionnaire and to record two voice samples. The main result was that sleep quality was associated with reductions in the maximum sound pressure level for vowel /i/. In the second study, college professors had meetings (in a Moodle platform), where they discuss about vocal hygiene practices, voice training exercises and adjustments of teaching-learning process to avoid voice misuse inside the classrooms. The main result was an improvement in vocal quality, reduction in vocal fatigue, and reduction of 2.5% in time dose. In conclusion, voice assessments and voice intervention programs conducted remotely showed good performance and positive effect on voice functioning among college professors.
Long time-series analysis from a directional acoustic sensor near Monterey Bay
Authors: Smith Kevin B. , Leary Paul , Deal Thomas , Joseph John E. , Miller Chris , Ryan John P. , Dawe Craig
Published: June 2021

A reduction in commercial shipping was reported during the first half of 2020 in response to the COVID-19 pandemic. The goal of this analysis is to determine if this impact on shipping resulted in a corresponding reduction in low-frequency ambient noise levels off the coast of Monterey Bay, California. Data presented here was collected on a Naval Postgraduate School directional acoustic sensor deployed on the Monterey Accelerated Research System’s cabled observatory, managed by the Monterey Bay Aquarium Research Institute. The directional acoustic sensor was developed by GeoSpectrum Technologies, Inc for integration onto the observatory system, and was initially installed in February, 2019. Since then, the data has been continuously streaming to a server at the Naval Postgraduate School for subsequent processing. In this work, long time-series analysis is performed to compare year-to-year statistics of month-long data sets through the end of January, 2021. Spectral probability densities are computed for each month over the 1/3 octave band for both amplitude and direction. Annual variations of the 50th percentile statistics are evaluated to determine if the shipping reduction due to COVID-19 is a distinguishable feature in the data.
Long-term noise interferometry analysis in the northeast Pacific Ocean
Authors: Ragland John , Abadi Shima
Published: June 2021

Noise interferometry is the method of passively estimating acoustic propagation using ambient sound. It has been used for long-term ocean monitoring applications such as tomography, thermometry, and measuring flow velocity. Using noise interferometry, the time domain Greene’s function (TDGF) between two locations can be estimated. In this talk, we use 6 years (2015–2020) of acoustic data recorded by two hydrophones in the northeast Pacific Ocean to analyze the long-term TDGF. The hydrophones are deployed at the Cabled Array which is maintained by the Ocean Observatories Initiative (OOI). They are separated by 3.2 km, located on the ocean floor at a depth of 1500 m, and have a sampling rate of 200 Hz. We calculate the signal-to-noise ratio (SNR) of the TDGF estimate for different propagation paths and study how it varies for different average times, local shipping densities, and oceanographic variables such as sound speed. [Work supported by ONR.]
Tutorial on finite-difference time-domain (FDTD) methods for room acoustics simulation
Authors: Hamilton Brian
Published: June 2021

Wave-based simulation models for acoustics have remained an active area of research and development for the past three decades. Wave-based methods aim to solve the 3D wave equation directly and therefore have large computational costs relative to conventional ray-based methods, which tend to simplify wave-diffraction effects. However, wave-based methods offer the potential of complete numerical solutions, including all wave-scattering and diffraction effects over the full audible bandwidth. Additionally, wave-based methods are highly parallelisable, making them amenable to parallel computing architectures such as graphics processing units, which can greatly cut down lengthy simulation times. This tutorial will give an introduction to wave-based methods for room acoustics with a focus on the finite-difference time-domain (FDTD) method. The basic concepts behind FDTD methods, along with practical implementation issues, will be discussed and illustrated with examples. The relationship of FDTD methods to other wave-based methods, along with differences to ray-based methods, will be explained. Also, the use of graphics processing units (GPUs) with freely available FDTD software will be discussed.
Parabolic equations in motionless and moving media
Authors: Ostashev Vladimir , Wilson D. Keith
Published: June 2021

The narrow-angle parabolic equation (NAPE) provides a robust approach for sound propagation in inhomogeneous media such asthe atmosphere and ocean. Several numerical methods for solving the NAPE in a motionless medium have been developed. The Crank-Nicholson finite-difference method is one of the simplest and readily supports range-dependent environmental processes such as turbulence. The NAPE, boundary condition, and artificial absorbing layer are discretized, and the solution is written in a matrix form. A starting field, which approximates the sound source, is marched forward by solving a matrix equation. Because the matrices involved are triagonal, the solution is highly efficient. For many applications in atmospheric and ocean acoustics, the NAPE needs to be generalized for wide-angle propagation and moving media (winds or currents). Recently derived wide-angle parabolic equations (WAPEs) in moving media are reviewed including the phase errors pertinent to the equations. In the Pade (1,1) and high-frequency approximations, the WAPE in a moving medium with arbitrary Mach numbers is surprisingly simple. It can be implemented numerically with minimal modifications to existing Crank-Nicholson NAPE solvers.
Uncertainty quantification in acoustics through generalized polynomial chaos expansions
Authors: Wixom Andrew S. , Walters Gage S.
Published: June 2021

Modeling and simulation has become increasingly important within acoustics to support system design and evaluation while reducing the need for expensive or sometimes unattainable field experiments. Much time and money has been invested in developing computational models that propagate known (deterministic) input data through a deterministic, and often very complex system to generate the relevant outputs of interest. System performance in real environments is, however, subject to uncertainties arising from incomplete knowledge of the input data as well as approximations made in generating the system model. In this tutorial talk, we will review the generalized polynomial chaos (GPC) method for propagating uncertainties through a deterministic computational acoustics model given probability distributions for the unknown quantities. Our approach uses stochastic collocation which permits reuse of deterministic acoustic codes so that the GPC is implemented as a wrapper code, rather than requiring a new complex model to be built. We then suggest a framework for general uncertainty quantification starting with informed probabilistic modeling of input, through interpretation of the GPC output, and illustrate with a structural acoustics example problem.
From single-ended to push-pull electrostatic MEMS speakers for in-ear audio applications
Authors: Ehrig Lutz , Schenk Hermann A. G. , Wall Franziska , Melnikov Anton , Kaiser Bert , Langa Sergiu , Stolz Michael , Monsalve Guaracao Jorge Mario , Mrosk Andreas , Conrad Holger
Published: June 2021

Recently, a new approach for an all-silicon MEMS-based microspeaker has been presented for in-ear applications. The volume displacement is generated by multiple electrostatic actuated beams called “Nanoscopic Electrostatic Drives” (NED) that move in lateral direction between a top and a bottom silicon wafer. The top and the bottom wafers are provided with openings through which air can flow in and out. Two fundamentally different actuator designs have been realized: An asymmetric electrostatic pull-actuator and an electrostatic push-pull actuator. While the push-pull actuator can be actively displaced in both directions, the pull actuator can only be displaced actively in one direction and therefore requires an offset voltage to oscillate around a working point. These different driving schemes have a major impact on stability and harmonic distortions. In this presentation, MEMS speakers realized using both approaches will be compared and the impact on acoustic performance will be demonstrated.
Introduction to modeling and analysis of small, piezoelectrically excited bending-wave loudspeakers
Authors: Anderson David
Published: June 2021

Piezoelectric patches are used to excite panels into bending vibration, allowing the screens or cases of smartphones, tablets, laptops, and other small electronic devices to produce sound without traditional microspeakers. This paper presents an introduction to modeling and analyzing the acoustic response of such devices, assuming the use of a piezoelectric patch exciter driven with a 10 VRMS signal. Simulations are performed with respect to four design factors (piezoelectric patch size, piezoelectric patch location, panel material, and panel enclosure depth) as well as three performance metrics [low-frequency cutoff point, mean sound pressure level (SPL) above cutoff, and the standard deviation of SPL above cutoff]. Results demonstrate several key relationships, such as: larger patch sizes create higher mean SPLs, smaller enclosures create higher mean SPLs but also higher cutoff points, and larger enclosures create more deviation in the measured SPL. Additional design factors are identified and discussed which will impact practical designs.
Quantifying ship noise in the marine soundscape of the western Canadian Arctic
Authors: Halliday William D. , Insley Stephen
Published: June 2021

The Arctic soundscape is naturally quite complex, but many parts of the Arctic have also historically had very low levels of ship noise. However, ship traffic is increasing throughout the Arctic, which is likely leading to increased levels of underwater noise, causing changes in this soundscape. In this study, we thoroughly quantified ship noise in passive acoustic data collected at 10 sites in the western Canadian Arctic between 2014 and 2020, with data collected from between one and three years at each site. We paired the acoustic data with automatic identification system ship data to collect information on the individual ships creating noise. We quantified the presence of ship noise within all of the acoustic data, statistically examined the influence of different static and dynamic ship variables on sound levels, and estimated source levels of ships that traveled close to the acoustic recorder. These analyses represent the first detailed examination of ship noise in this region of the Arctic, and the results provide valuable information for future soundscape studies, as well as relevant information for the management of ship noise in the Arctic.
Voicing contrasts and prosody in Majhi
Authors: Noah Usman Panjabi
Published: June 2021

This project examines the understudied phonetic inventory of Majhi Panjabi, particularly the factors that contribute to the perception of a three-way voicing contrast in stops and affricates: falling pitch contour and de-aspiration of following consonants. I further explore the possible impact of contact with the non-tonal qualities of Urdu in this change.
Effect of the reduction in passengers on excessive subway noise in NYCT stations
Authors: Murray Patrick , Schnitta Bonnie
Published: June 2021

An examination is made on the reduced number of passengers riding the NYCT subway and its effect on the average reverberation time within the subway stations. Excessive reverberation times can have the effect of compounding the noise from train operation, including breaking and other noises. Approximations are made of the reverberation time at selected subway platforms and how those have changed during the COVID-19 pandemic. Approximations are made of the potential hearing impacts on the remaining subway commuters and staff.
Experimental investigation of low Reynolds number rotor noise
Authors: Gojon Romain , Jardin Thierry , Parisot-Dupuis Hélène
Published: June 2021

In this paper, an experimental characterisation of low Reynolds number rotors is performed in an anechoic room. Two commercially available two-bladed rotors as well as four three-dimensional (3D)-printed rotors with different numbers of blades (from two to five) are tested. The latter have canonical geometry, with an NACA0012 blade section profile, extruded in the radial direction with constant chord and constant 10° pitch. The experimental setup and the 3D printing strategy are first validated using results from the literature for the commercially available rotors. For all the tested rotors, four noise characteristics are analysed: the overall sound pressure level (OASPL), the amplitude of the blade passing frequency (BPF), and the amplitude of its first harmonic and the high-frequency broadband noise. For all the rotors, an increase in all noise characteristics is observed with the rotational speed (rpm) for all directivity angles. Moreover, an interesting change of pattern is observed for the amplitudes of the BPF and of its first harmonic, with, in the vicinity of the rotor plane, a minimum value for low rpm and/or high number of blades, and a maximum value for high rpm and/or low number of blades. This change in directivity leads to a similar change of directivity of the OASPL. For the broadband noise, a dipole-like pattern is obtained with a minimum value at θ=−10°, i.e., aligned with the trailing edge and thus indicating the generation of trailing edge noise. Finally, scaling laws that characterise the amplitude of the different noise components with respect to the rpm are proposed.
Recommended snapshot length for acoustic point-transect surveys of intermittently available Cuvier's beaked whales
Authors: Barlow Jay , Trickey Jennifer S. , Schorr Gregory S. , Rankin Shannon , Moore Jeffrey E.
Published: June 2021

Acoustic point-transect distance-sampling surveys have recently been used to estimate the density of beaked whales. Typically, the fraction of short time “snapshots” with detected beaked whales is used in this calculation. Beaked whale echolocation pulses are only intermittently available, which may affect the best choice of snapshot length. The effect of snapshot length on density estimation for Cuvier's beaked whale (Ziphius cavirostris) is investigated by sub-setting continuous recordings from drifting hydrophones deployed off southern and central California. Snapshot lengths from 20 s to 20 min are superimposed on the time series of detected beaked whale echolocation pulses, and the components of the density estimation equation are estimated for each snapshot length. The fraction of snapshots with detections, the effective area surveyed, and the snapshot detection probability all increase with snapshot length. Due to compensatory changes in these three components, density estimates show very little dependence on snapshot length. Within the range we examined, 1–2 min snapshots are recommended to avoid the potential bias caused by animal movement during the snapshot period and to maximize the sample size for estimating the effective area surveyed.
Deep learning-based direction-of-arrival estimation for multiple speech sources using a small scale array
Authors: Zhang Min , Pan Xiang , Shen Yining , Qiu Jianjun
Published: June 2021

A high resolution direction-of-arrival (DOA) approach is presented based on deep neural networks (DNNs) for multiple speech sources localization using a small scale array. First, three invariant features from the time-frequency spectrum of the input signal include generalized cross correlation (GCC) coefficients, GCC coefficients in the mel-scaled subband, and the combination of GCC coefficients and logarithmic mel spectrogram. Then the DNN labels are designed to fit the Gaussian distribution, which is similar to the spatial spectrum of the multiple signal classification. Finally, DOAs are predicted by performing peak detection on the DNN outputs, where the maximum values correspond to speech signals of interest. The DNN-based DOA estimation method outperforms the existing high resolution beamforming techniques in numerical simulations. The proposed framework implemented with a four-element microphone array can effectively localize multiple speech sources in an indoor environment.
A place to share teaching resources: Speech and language resource bank
Authors: Tucker Benjamin V. , Kelley Matthew C. , Redmon Charles
Published: June 2021

One of the major difficulties of teaching is accessing the vast amounts of material/resources already available to instructors. The Speech and Language Resource Bank (SLRB) is a platform and central repository for sharing, managing, and growing community resources for teaching and research in the speech and language sciences.
To study swarming cicadas, it takes a crowd
Authors: Graber-Stiehl Ian
Published: June 2021

Cellphone-wielding observers track when and where the insects emerge.
Canonical T cell receptor docking on peptide–MHC is essential for T cell signaling
Authors: Zareie Pirooz , Szeto Christopher , Farenc Carine , Gunasinghe Sachith D. , Kolawole Elizabeth M. , Nguyen Angela , Blyth Chantelle , Sng Xavier Y. X. , Li Jasmine , Jones Claerwen M. , Fulcher Alex J. , Jacobs Jesica R. , Wei Qianru , Wojciech Lukasz , Petersen Jan , Gascoigne Nicholas R.J. , Evavold Brian D. , Gaus Katharina , Gras Stephanie , Rossjohn Jamie , La Gruta Nicole L.
Published: June 2021

Making sense of TCR–pMHC topology

Most T cells use a T cell receptor (TCR) that recognizes major histocompatibility complex molecules bound to peptides (pMHCs) derived from both self- and foreign antigens. Although there is great variability in the interface because of the diversity of both partners, this interaction displays a canonical docking topology for reasons that remain contested. Zareie
et al.
tested an assortment of both canonical and reversed-polarity TCRs that were all specific for the same cognate pMHC-I bearing a peptide derived from influenza A virus (IAV) (see the Perspective by Horkova and Stepanek). The authors determined that docking topology was the primary driver of in vivo T cell activation and recruitment when mice were infected with IAV. The canonical topology was required for the formation of a functional signaling complex, suggesting that T cell signaling constraints dictate how TCR and pMHC meet.

Science
, abe9124, this issue p.
eabe9124
; see also abj2937, p.
1038
Reciprocal repulsions instruct the precise assembly of parallel hippocampal networks
Authors: Pederick Daniel T. , Lui Jan H. , Gingrich Ellen C. , Xu Chuanyun , Wagner Mark J. , Liu Yuanyuan , He Zhigang , Quake Stephen R. , Luo Liqun
Published: June 2021

Keeping brain development untangled

Brain circuits established during development can be overlapping or parallel as needed. Pederick
et al.
analyzed how parallel circuits in the mouse medial and lateral hippocampus develop without getting tangled up. Regulated expression of the cell surface molecules teneurin-3 (Ten3) and latrophilin-2 (Lphn2) keeps confusion at bay. Together, these factors act as a membrane-bound ligand-receptor pair with repulsive outcomes, and they are able to destabilize a nascent but incorrect axon-target interaction. Individually, they each mediate homophilic attraction as axons search for their favored targets.

Science, abg1774, this issue p.
1068
Response to Comment on “Individual heterozygosity predicts translocation success in threatened desert tortoises”
Authors: Scott Peter A. , Allison Linda J. , Field Kimberleigh J. , Averill-Murray Roy C. , Shaffer H. Bradley
Published: June 2021

Hedrick brings up several potential concerns that he feels challenge or limit our main finding. Hedrick does not comment on our empirical results, but rather argues that several factors may confound or invalidate our conclusion. Many of these concerns focus on unknown ecological aspects of the translocated tortoises, but we believe there is no reason to conclude that they bias the results or interpretation as presented in our original paper.
Calibrating experiments at atom-crushing pressures
Authors: Jeanloz Raymond
Published: June 2021

Shockless compression of platinum and gold provides pressure standards to >1 terapascal
Routine separation of staphylococci from micrococci based on bacteriolytic activity production
Authors: Varaldo P E , Grazi G , Cisani G , Satta G
Published: June 2021

A new method is described by which separation of staphylococci from micrococci can be achieved in routine laboratory use. The basis of this method is that bacteriolytic activity is produced by staphylococci but not by micrococci.
Comparison of occurrence of antibodies to human cytomegalovirus as demonstrated by immunofluorescence and indirect hemagglutination techniques
Authors: Michelson S , Cabau N , Boue A , Horodniceanu F
Published: June 2021

Indirect immunofluorescence and hemagglutination study of reactivity to human cytomegalovirus immediate early, early, and late antigens revealed that antibody responses to these antigens varies greatly and that hemagglutination is positive when sera contain only antibody to one or both early antigens.
Comparison of staphylococcal coagglutination, latex agglutination, and counterimmunoelectrophoresis for bacterial antigen detection
Authors: Thirumoorthi M C , Dajani A S
Published: June 2021

Soluble antigens of Haemophilus influenzae type b, Streptococcus pneumoniae, Neisseria meningitidis, and group B streptococcus were looked for in cerebrospinal fluid, serum, and urine by using the staphylococcal coagglutination test, latex agglutination test, and counterimmunoelectrophoresis. The staphylococcal coaggultination and latex agglutination tests were more sensitive than counterimmunoelectrophoresis in identifying antigens of H. influenzae type b, S. pneumoniae, and N. meningitidis. None of the three tests successfully detected group B streptococcal antigens in body fluids. Nonspecific reactions noted with the staphylococcal coagglutination test could be usually eliminated after premixing test specimens with soluble protein A.
Sensitive microplate enzyme-linked immunosorbent assay for detection of antibodies against the scrub typhus rickettsia, Rickettsia tsutsugamushi
Authors: Dasch G A , Halle S , Bourgeois A L
Published: June 2021

A microtiter enzyme-linked immunosorbent assay (ELISA) has been developed for the titration of antibodies against scrub typhus in human and animal sera. Scrub typhus rickettsiae were grown in monolayers of irradiated mouse LM3 cells and separated from host cell materials by differential centrifugation, filtration through a glass filter (AP-20, Millipore Corp.), and isopycnic banding in Renografin density gradients. The scrub typhus ELISA antigens were obtained from the purified viable rickettsiae by French pressure cell disruption and addition of 0.2% Formalin to the soluble extract. Antisera prepared in rabbits against the prototype Karp, the Kato, and the Gilliam strains of scrub typhus were used to standardize the ELISA and to compare its sensitivity and specificity to that of the indirect fluorescent antibody test (IFA). ELISA titers were measured as the greatest serum dilution showing an optical density 0.25 above controls or by the optical density achieved at a fixed serum dilution. The IFA and ELISA end point titers were quite similar, and all three measures of titer had comparable specificity for the strains of scrub typhus. No cross-reactions between the typhus and scrub typhus wera were observed by ELISA. Both the immunoglobulin M (IgM) and IgG antibody titers of 12 sequential sera from four patients with scrub typhus were obtained by IFA and ELISA. The IFA and ELISA end point titers for IgM and IgG had correlation coefficients of 0.91 and 0.97, respectively, whereas the ELISA optical density values at a serum dilution of 1:100 had slightly lower correlations with IFA titers (0.80 and 0.94). Early rising IgM titers followed by rising IgG titers were demonstrated by ELISA in three patients with primary scrub typhus infections, whereas the IgG response predominated in a patient with a reinfection. It is concluded that the ELISA for scrub typhus is a very satisfactory alternative to the IFA test.
Serotypes and Antibiotic Susceptibilities of
Pseudomonas aeruginosa
Isolates from Single Sputa of Cystic Fibrosis Patients
Authors: Seale Thomas W. , Thirkill Hilary , Tarpay Martha , Flux Marinus , Rennert Owen M.
Published: June 2021

A phenotypic characterization of
Pseudomonas aeruginosa
from single sputum samples of 21 typical cystic fibrosis patients indicated a high frequency of heterogeneity among isolates on the basis of differences in antibiotic resistance, colony morphology, pigmentation, and serotype. Two or more isolates with different but stable susceptibilities to carbenicillin, gentamycin, streptomycin, tetracycline, chloramphenicol, and sulfamethoxazole plus trimethoprim were detected in 38% of the sputa. Differences generally were independent of the mucoid state of the strain. O-antigen group determination with the Difco typing set showed that two or more serologically distinct strains were present in 10/21 sputum specimens. Nonmucoid derivatives of mucoid isolates almost always retained both the antibiotic susceptibilities and serotype of their parent strain. These data suggest that cystic fibrosis patients may be cocolonized/coinfected by different strains of
P. aeruginosa
more frequently than generally believed. Alternatively, phenotypically distinct strains from a single patient might arise as phenotypic dissociants from a single infecting strain. Because of the frequency and multiplicity of phenotypically distinct
P. aeruginosa
isolates which we obtained from our cystic fibrosis patients, it is important to select multiple isolates from sputum cultures for antimicrobial susceptibility testing so as to assess adequately the susceptibility of this organism to antibiotic therapy in cystic fibrosis. We recommend that several colonies of each distinguishable colony type of
P. aeruginosa
be pooled for the antibiogram.
Comparison of four plating media for isolating Vibrio cholerae
Authors: Morris G K , Merson M H , Huq I , Kibrya A K , Black R
Published: June 2021

Two brands of thiosulfate citrate bile salts sucrose agar and Monsur taurocholate tellurite gelatin (TTG) agar were compared with two newly developed media, sucrose tellurite teepol agar and Vibrio parahaemolyticus agar for isolation and identification of Vibrio cholerae. The thiosulfate citrate bile salts sucrose and TTG agars were the best selective media, whereas sucrose tellurite teepol agar was the poorest. Both TTG and sucrose tellurite teepol agars were good for use in follow-up serological tests, whereas only TTG agar could be used for follow-up oxidase tests. In our opinion TTG agar has more advantages for cholera research laboratories routinely culturing large numbers of patients for cholera on a daily basis and where media needs can be accurately predicted. In contrast, in smaller clinical laboratories or in laboratories investigating epidemics, thiosulfate citrate bile salts sucrose agar is best because it is commercially available and easy to prepare and can be used to distinguish colonies of suspect V. cholerae from V. parahaemolyticus.
Recovery of Haemophilus influenzae from twenty-three blood culture media
Authors: Schell R F , Le Frock J L , Babu J P , Robinson D B
Published: June 2021

Haemophilus influenzae is an important agent of bacteremia and has fastidious growth requirements. The purpose of this investigation was to determine the ability of commercial blood culture media to support the growth of this fastidious microorganism. Twenty-three types of blood culture media were inoculated with individual suspensions of eight strains of H. influenzae in the presence or absence of an erythrocyte-serum mixture. The rates of recovery of the H. influenzae strains from the various types of blood culture media were compared. The results demonstrated that the type of medium, the manufacturer, the erythrocyte-serum mixture, and the strain of H. influenzae influenced the recovery rates of H. influenzae. Optimal recovery of the strains of H. influenzae was obtained from brain heart infustion blood culture medium (GIBCO). Trypic soy broth (GIBCO) and supplemental peptone of Becton, Dickinson and Co. also were found to be superior to the remaining types of media tested for the recovery of H. influenzae.
Persistence of antibodies to rotavirus in human milk
Authors: Cukor G , Blacklow N R , Capozza F E , Panjvani Z F , Bednarek F
Published: June 2021

Human milk obtained from 21 American nursing mothers was studied for the presence of secretory immunoglobulin A antibody to rotavirus, the most common etiological agent of infantile gastroenteritis. Antibody was quantitated by adaptation of a recently described solid-phase radioimmunoassay technique that employs simian rotavirus as a convenient substitute antigen for human rotavirus. Of the mothers tested, 80% (12 of 15) possessed milk antibody within a week of parturition, whereas 56% of those tested (5 of 9) secreted milk antibody as late as 6 or 9 months postpartum. Specificity of the radioimmunoassay was demonstrated by absorption of antibody with purified rotavirus. Our detection by radioimmunoassay of antibody to rotavirus in milk samples collected past the colostrum stage is in contrast to other studies that have failed to detect antibody in human milk by immunofluorescence or neutralization tests. The present study also suggested that the appearance of secretory immunoglobulin A antibody in the milk of mothers previously lacking milk antibody may be correlated with subclinical infection of the mother with rotavirus.
Electron capture gas-liquid chromatographic-mass spectral identification of acids produced by Neisseria meningitidis in a defined medium
Authors: Alley C C , Brooks J B , Kellogg D S
Published: June 2021

The acid metabolites and the cellular fatty acids of three strains of Neisseria meningitidis grown in a chemically defined liquid medium were determined with computerized frequency-pulsed electron capture gas-liquid chromatography. Five acids not previously reported were subsequently identified: isobutyric, octanoic, decenoic (C10:1), dodecenoic (C12:1), and tetradecenoic (C14:1). These acids were produced during active metabolism and were not detected as cellular constituents. The frequency-pulsed electron capture gas-liquid chromatography methods which we used provide a rapid, reliable, sensitive means of detecting both these and other metabolic and cellular acids in spent culture medium.
Simplified chromatographic separation of immunoglobulin M from G and its application to toxoplasma indirect immunofluorescence
Authors: Pyndiah N , Krech U , Price P , Wilhelm J
Published: June 2021

The indirect immunofluorescent (IIF) antibody technique for the detection of Toxoplasma gondii immunoglobulin M (IgM) often gives false negative results, probably due to the competition between IgG and IgM. We therefore adapted a gel filtration procedure for the separation of IgG and IgM to a routine diagnostic test capable handling at least 10 sera per day and requiring only 50 microliters of serum. The results from 108 sera having positive complement fixation titers for Toxoplasma showed that 17 were IgM positive when the whole serum was tested by IIF compared with 55 positive when the IgM fraction was used. Sera with antideoxyribonucleic acid titers do not give false positive results after fractionation, and the removal of IgG eliminates false positive results due to rheumatoid factor. A prospective study showed that Toxoplasma IgM may persist up to 9 months.
Rapid identification of nonfermentative gram-negative rods by the Corning N/F system
Authors: Barnishan J , Ayers L W
Published: June 2021

A total of 1,298 nonfermentative gram-negative rods were used to evaluate the performance of the individual biochemical tests in the N/F System and to determine whether the observed results included sufficient key reactions for rapid identification. The system included an oxidase test, two screening tubes providing 5 test reactions designed primarily to identify pigment-producing strains of Pseudomonas aeruginosa, and a plate providing 12 test reactions designed to identify other nonfermenters. With both the tubes and plates, most results were consistent with expected conventional test reactions. Use of the tubes permitted the identification of 90% of the strains of P. aeruginosa in 24 h and 97% in 48 h. Use of the plates permitted the identification of 95% of the other oxidative nonfermenters within 24 h and 96% within 48 h. Only 26% of weak and nonoxidative nonfermenters were identified because of the nonreactivity of these organisms in this system. There were no misidentifications based on misleading test results.
Sensitive neutralization test for rubella antibody
Authors: Sato H , Albrecht P , Krugman S , Ennis F A
Published: June 2021

A modified rubella virus plaque neutralization test for measuring rubella antibody was developed based on the potentiation of the virus-antibody complex by heterologous anti-immunoglobulin. The test is highly sensitive, yielding titers on the average 50 to 100 times higher than the haemagglutination inhibition test or the conventional plaque neutralization test. The sensitivity of this enhanced neutralization test is somewhat limited by the existence of a prozone phenomenon which precludes testing of low-titered sera below a dilution of 1:16. No prozone effect was observed with cerebrospinal fluids. The specificity of the enhanced neutralization test was determined by seroconversion of individuals receiving rubella vaccine. Although the rubella hemagglutination inhibition test remains the test of choice in routine diagnostic and surveillance work, the enhanced rubella neutralization test is particularly useful in monitoring low-level antibody in the cerebrospinal fluid in patients with neurological disorders and in certain instances of vaccine failure.
Discrepancies in Weil-Felix and microimmunofluorescence test results for Rocky Mountain spotted fever
Authors: Hechemy K E , Stevens R W , Sasowski S , Michaelson E E , Casper E A , Philip R N
Published: June 2021

Only 4.2% of 284 single specimens and 17.6% of 51 pairs of sera reactive in Weil-Felix agglutination tests for Rocky Mountain spotted fever were confirmed by a specific Rickettsia rickettsii microimmunofluorescence test.
Compact anaerobic glove box for hospitals and research laboratories
Authors: Dickman M D , Chappelka A R , Aff C , Gerhard J , Orcutt R P
Published: June 2021

An anaerobic glove box designed for moderate-sized hospitals or research laboratories is described. The compact vinyl and metal enclosure becomes anaerobic rapidly after inflation, requires no vacuum pump, and provides incubator space equivalent to 15 standard anaerobic jars.
Septicemia caused by DF-2
Authors: Schlossberg D
Published: June 2021

Fatal septicemia due to an unidentified gram-negative rod developed in a 60-year-old alcoholic. Infection due to this organism has been reported only rarely in the medical literature. Like Pasturella multocida, this organism is related to dog bites, is gram negative, and is sensitive to penicillin.
Detection of pigment precursors in white clinical strains of Serratia marcescens
Authors: Katz D S , Sobieski R J
Published: June 2021

Filter paper strips containing a pigment precursor extracted from Serratia marcescens strain 933 were used to determine whether white, clinical S. marcescens strains could form pigment syntrophically. In all, 114 strains (113 of clinical origin) were tested, and 99% were found to develop colors ranging from violets to pinks.
Susceptibility of Staphylococcus aureus and group A, B, C, and G streptococci to free fatty acids
Authors: Heczko P B , Lütticken R , Hryniewicz W , Neugebauer M , Pulverer G
Published: June 2021

The susceptibility of 242 strains of Staphylococcus aureus and 117 strains of streptococci of groups A, B, C, and G to decanoic, dodecanoic, octadeca-9,12-dienoic, and octadeca-9,12,15-trienoic acids was estimated by determination of minimal inhibitory concentrations. S. aureus strains appeared to be generally less susceptible to all four fatty acids than streptococcal strains of all groups. Dodecanoic acid was the most inhibitory fatty acid against both staphylococci and streptococci. Both saturated fatty acids used were more active than the unsaturated acids. Among the unsaturated acids, octadeca-9,12,15-trienoic acid appeared to be more inhibitory for Staphylococcus and Streptococcus strains than octadeca-9,12-dienoic acid. No differences in susceptibility to fatty acids among staphylococcal and streptococcal strains isolated from skin, throat, or other sites were found.
Detection of adenovirus by enzyme-linked immunosorbent assay
Authors: Harmon M W , Drake S , Kasel J A
Published: June 2021

A solid-phase direct enzyme-linked immunosorbent assay (ELISA) was developed for the detection of adenovirus antigen in extracts of infected cells by using antihexon serum. Results with simulated clinical specimens consisting of normal nasal wash specimens seeded with varying concentrations of adenovirus type 5 showed that antigen could be detected in extracts of HEp-2 cell cultures inoculated with 10(2.5) 50% tissue culture infective doses (TCID50) and 10(1.5) TCID50 after 2 and 4 days of incubation, respectively. Fifty-three clinical nasal wash specimens containing adenovirus type 5 (stored for 5 years at -70 degrees C) were used to evaluate antigen detection by ELISA in HEp-2 cell extracts and by manifestation of cytopathic effect in human embryonic kidney cells. After 2 days of incubation, 62% were positive by ELISA, whereas none was positive for cytopathic effect. After 4 days of incubation, 76% were ELISA positive and 47% were positive for cytopathic effect. The results according to infectivity titers indicated that clinical specimens containing 10(3.0) TCID50 or greater were all positive by ELISA after 2 days of incubation in HEp-2 cells, and by 4 days all but one specimen containing 10(2.0) TCID50 or greater were ELISA positive. ELISA and immunofluorescent methods for antigen detection were compared using 24 of the 53 clinical specimens containing adenovirus type 5. Nearly equivalent sensitivities were demonstrated. These results suggest that ELISA may provide an alternative method of detecting and identifying adenoviral infections in humans.