bluuebunny/crossref_metadata_2025 huggingface dataset:
Gaussian Quadrature Ranges with Observed Sound Speed Profiles
Authors: Floyd Edward R. , Pugh James D.
Published: May 2012

For observed sound speed profiles, the range to a noise source in the first convergence zone is calculated numerically by applying Gaussian quadrature techniques of various orders to the ray tracing range integral. The observed profile is tabulated for standard oceanographic depths. The tabulated profile is mapped into the sample set for Gaussian quadrature principally by cubic splines. The ray path integral for range is divided into convenient segments in consonance with the cubic splines, and the appropriate Gaussian quadrature is applied consistent with the singular points encountered along the ray path segment. The rate of convergence of successive orders of the Gaussian quadrature technique is examined. Our preliminary results show that the root-mean-square difference between fifth-order and sixth-order Gaussian quadrature range calculations is 0.192 yd.
An Asymptotic Approximation for the Computation of the Acoustic Field in a Surface Duct
Authors: Labianca Frank. M. , Harper Edward Y.
Published: May 2012

A complete physical description of the point-source-excited acoustic field in a surface duct is given. This is accomplished by means of an asymptotic analysis of the depth-eigenfunction representation. Three spatial regions, each corresponding to a particular range of eigenvalues, are established. The region nearest the source is described by classical ray theory while the farthest region (where energy trapping and leakage occurs) is described by virtual-mode theory. A transition region connecting the other two is defined, and asymptotic formulas are derived which link the associated acoustic fields. These formulas are then used to compute propagation loss in the presence of a surface duct. Numerical results are presented and discussed.
A Normal Mode Method of Solution for Deep Ocean Propagation
Authors: Zabalgogeazcoa X. , Weinberg N. L.
Published: May 2012

The sound velocity distribution in the ocean is considered a function of depth only. The ocean model is separated into three layers. The surface and bottom layers are represented by linear profiles while the middle layer is assumed to have a velocity profile described by a polynomial. The bottom layer is unbounded, and therefore only one solution to the wave equation is needed to describe the field in it. The bounded surface and middle layers require two solutions of the wave equation to depict the “outgoing” and “uncoming” waves. The solutions for the linear regions are in terms of Bessel functions whereas the field in the middle region is defined by two infinite series. After application of the boundary conditions, the constants of the solutions can be determined, and a normal mode evaluation of the solution is given. For typical profiles off the coast of Eleuthera, the integral representation of the solution is found to be rapidly convergent. The Gaussian approximate method for numerical evaluation is used for evaluation of the field.
Integral Equation Methods for Scalar Interface Problems
Authors: DeSanto John A.
Published: May 2012

The various forms that the generalized integral equations for the Green's function of a rough interface can assume are discussed. The interface separates two semi-infinite media of different density and sound speed. The equations arise by applying Green's theorem in both upper and lower media using an appropriate free-space Green's function. Continuity conditions at the interface on the Green's function and its normal derivative relate the two media. Types of equations which can be generated include integro-differential equations which involve the surface values of both the Green's function and its normal derivative, mixed surface-volume integral equations, and a surface integral equation -involving only the surface value of the Green's function.
Coupled-Circuit Representation of the Vibrations of a Thin Ferroelectric Cylindrical Shell
Authors: Rudgers Anthony J.
Published: May 2012

This paper describes a lumped-parameter equivalent circuit that represents the radially symmetric vibratory motion of a finite-length cylindrical shell, which is composed of a radially poled ferroceramic material of the barium titanate type. The equivalent circuit consists of two branches that are coupled together. One branch describes the axial motion of the cylindrical shell and the other branch the radial motion. Such a two-branch equivalent circuit is necessary, since the radially symmetric vibration of a finite-length cylindrical shell is a two-dimensional problem, owing to the fact that the radial and axial motions are closely coupled due to the finiteness of the Poisson's ratio of the shell material. The equivalent circuit is derived using membrane shell theory and is thus able to describe the motion of the cylindrical shell at frequencies up to and including the lowest radial and axial resonances. By means of this circuit, it is possible to analyze the effect of axial boundary conditions when designing transducers that use the radial motion of thin cylindrical shells in the generation and reception of underwater sound.
Electronic Correlator for Diffusion Studies
Authors: Proctor T. M.
Published: May 2012

We have built, from off-the-shelf arithmetic modules, an electronic cross-correlator which measures R = p1p2¯/(p12p22¯)12 as a function of the distance from point 1 to point 2. It is compact, accurate, and stable. To illustrate its use, we have made surveys along a horizontal diagonal of the NBS reverberation room. Pure tones, FM signals, and 13-octave bands of noise were used at frequencies (or center frequencies) in the range 125–2000 Hz. In some cases microphone No. 1 was fixed and No. 2 was moved, but in most cases the microphone separation was fixed at λ/2, for which R = 0 in the case of a three-dimensional diffuse field, and the array translated slowly along the diagonal. The second method appears to be the better.
Speech Synthesis System Integrating Formant-Coded Words and Computer-Generated Stress Parameters
Authors: Levinstone D. S. , Schafer R. W. , Rabiner L. R. , Coker C. H. , Umeda N.
Published: May 2012

This paper describes an experiment in which an earlier system of speech synthesis based on concatenation of formant-coded words [Rabiner, Schafer, and Flanagan, “Speech Synthesis by Concatenation of For-mant Coded Words,” Bell Syst. Tech. J. (May 1971)] was integrated with an automatic system for generating prosodic information [Coker, Umeda, and Browman, “Automatic Synthesis for Ordinary English Text,” IEEE Trans. Audio Electrnacoust. (June 1973)]. An experimental investigation of the resulting system was made to determine the importance of various prosodic factors on the general quality of the synthetic speech. Of primary concern were procedures for altering the pitch and timing of the basic word data as well as the method of merging isolated words at the boundary between words. Listener preference tests were conducted with the aim of determining which. factors were important in improving the general quality of the synthetic speech. The results of these tests indicate that the rule-generated prosody was preferred to simple alternatives such as obtaining prosodic information directly from the isolated words that comprise the utterance. Several examples of utterances synthesized by the resulting system are given.
Effects of Soft-Wall Vibration and Radiation in a Dynamic Model of the Vocal Cords and Vocal Tract
Authors: Ishizaka K. , Shipley K. , Flanagan J. L.
Published: May 2012

At the previous meeting of the Society, we described a computer model of the vocal cords and vocal tract system in which dynamic, physiologically based control functions accomplish speech synthesis [J. L. Flanagan, K. Ishizaka, and K. Shipley, “Dynamic Control of a Computer Model of the Vocal Cords,” J. Acoust. Soc. Am. 54, 319(A) (1973)]. The model has been extended to include the effects of vibration and radiation of the soft walls of the vocal tract. The influence of yielding walls upon the mode structure (formants) of the vocal system, upon the cord-tract acoustic interaction, and upon sound output during total occlusion is studied and reported. Articulatory dynamics of an intervocalic, voiced labial stop are used as a vehicle to expose the detailed behavior of the model. During occulsion, wall yielding is shown to contribute to sustenance of voicing, and wall radiation accounts for sound output. A computer movie film, generated at a slow-motion rate of 100 times real time, illustrates the coordinated interplay of cord and tract motion.
Interactive Editing of Digitally Recorded Speech
Authors: Nakatani Lloyd H.
Published: May 2012

Digital recordings of speech enjoy many advantages over analog recordings. Among the advantages are a noise-free and linear recording medium, addressable information, and digital signal processing. Unfortunately, digital tapes cannot be edited by cutting and splicing. This disadvantage is more than overcome with an interactive editing program implemented on a small laboratory computer. Segments are easily cut out of a master recording with the look-and-listen feedback capability of the program. Once cut out, the segments can be recorded on either digital or analog tape in any prescribed format and in any order. The program has proved very useful for preparing stimulus tapes for speech experiments. General design principles of input-output, display and audio capabilities, commands, segment manipulation, and hardware requirements found useful in interactive tape editing are described.
Jamming Signals for FM Bat Echolocation
Authors: Simmons James A. , Lavender W. A. , Lavender B. A.
Published: May 2012

Jamming experiments were conducted to assess the effectiveness of several different types of signals for interfering with the ability of echolocating bats (Eptesicus fuscus) to discriminate target range. Random interfering noise covering the bat's sonar bandwidth of 25–50 kHz must be sufficiently intense for the echo signal-to-noise ratios to approach 0 dB before marked breakdown of echolocation occurs. This is true for continuous noise, intermittent noise, and for noise incorporating internal correlation at the same period as the travel time of sounds going to and from the targets. FM interference is 30 to 40 dB more effective in jamming the bat than random noise of the same spectrum. The results suggest that the bat's sonar receiver applies frequency-sweep criteria to incoming sounds to decide whether potential echoes are present. Neurons with properties appropriate to this filtering function, analogous to motion detection in vision, are known to exist in the bat's auditory nervous system.
Target and Echo “Fine-Structure” Discrimination by Echolocating Bats
Authors: Simmons James A. , Lavender B. A. , Lavender W. A.
Published: May 2012

Echolocating bats of the species Eptesicus fuscus were trained to discriminate among a series of targets which reflected echoes differing systematically in ultrasonic echo spectra. The echoes did not differ significantly in nonspectral information such as overall intensity. The results of the experiment indicate that Eptesicus can detect displacements of 1 kHz or less in the positions of energy peaks at different frequencies in echo spectra. These bats apparently can identify target shape from echo spectral information alone. Such discriminations may mediate the selection or rejection of airborne insect prey and may contribute to the partitioning of food resources among sympatric species of echolocating bats. Not only can bats resolve small time-domain differences between echoes, as in target ranging, but they are also able to resolve small variations in the distribution of energy in the frequency domain. Is the same sonar receiver used for both tasks?
Excitation, Inhibition, and Disinhibition in the Inner Ear of the Toad (Bufo)
Authors: Capranica R. R. , Moffat A. J. M.
Published: May 2012

Three distinct types of auditory fibers are found in the VIIIth nerve of the American toad (Bufo americanus). One type is maximally excited by low-frequency tones (100–500 Hz), the second type by mid-frequencies 500–1000 Hz, and the third type by higher frequencies 1100–1700 Hz. Low-frequency units can be inhibited by the addition of a second tone in the mid-frequency range. For total inhibition, the second tone generally must be 10–30 dB more intense than the first. Excitatory and inhibitory tuning curves are disjoint. Total inhibition can be completely disinhibited by the addition of a third tone of approximately equal intensity but higher in frequency than the inhibitory tone. The frequency difference between the best inhibitory and best disinhibitory tones is approximately the best excitatory frequency of the unit. Our results suggest that disinhibition originates from a nonlinear mechanism in the inner ear which is operative even at relatively low intensity levels. Mid- and high-frequency units cannot be inhibited. The peripheral auditory system of the little green toad (Bufo debilis) is similarly organized, except that the high-frequency units respond best to 3000–3600 Hz. The significance of this organization in detection of natural sounds will be discussed. [Supported by NSF Grant GB-18836 and NIH Grant NS-09244.]
Absolute and Differential Frequency Sensitivity in the Parakeet (Melopsittacus undulatus)
Authors: Dooling R. J. , Saunders J. C.
Published: May 2012

Avoidance conditioning and a modified method of limits were used to measure the absolute threshold for pure tones from 0.25 to 8.5 kHz and the frequency difference limen in eight parakeets. The parakeet audibility curve shows greatest sensitivity at 2.86 kHz and resembles a narrow bandpass filter. High-frequency sensitivity decreases at the rate of 40 dB/octave above 2.86 kHz. For frequencies below 2.86 kHz, sensitivity decreases at the rate of about 15 dB/octave. Direct measures of the frequency difference limen at six frequencies between 0.50 and 5.7 kHz show a sensitivity only two to three times worse than man. The Weber fraction (Δf/f) for the parakeet is essentially flat at 0.007 over the frequency range from 1.0 to 4.0 kHz.
The Relations between Vocalizations and Hearing Capability in the Parakeet (Melopsittacus undulatus)
Authors: Saunders J. C. , Dooling R. J.
Published: May 2012

Sixteen vocalizations from four parakeets were acoustically analyzed. A call usually lasted 140–160 msec and contained between seven and nine notes. The power spectrum of the call indicated that most of the energy was contained in a narrow band of frequencies between 2.0 and 4.0 kHz. These frequencies were also the region of best sensitivity in the parakeet audibility curve. A time-frequency spectrum was also obtained by measuring the frequency of the first cycle in successive 1.0-msec steps throughout the call. This analysis revealed that the calls could be discriminated on the basis of whether the first or last note contained relatively pure frequencies. The “constancy of intonation” (Δf/f) was determined for these notes by calculating the standard deviation of the within-note frequency variations (Δf) and dividing it by the center frequency (f). The “constancy of intonation” was only one to two times larger than the frequency DLs in this species and supports the hypothesis that vocalization performance is related to hearing capacity in birds.
Vocal Repertoire of a Subterranean Rodent (Spalax)
Authors: Capranica R. R. , Nevo E. , Moffat A. J. M.
Published: May 2012

Mole rats (Spalax ehrenbergi) are blind, normally solitary, subterranean rodents found in southeast Europe and throughout the Middle East. Animals in Israel were captured in their burrows and maintained in laboratory cages for direct observation. They were found to be highly vocal, especially during physical encounters with each other. Their vocal repertoire consists of at least six call types, each occurring in a different behavioral context. The energy in all of the signals is below 8 kHz; some of the calls have most of their energy below 1 kHz. The temporal and spectral characteristics of these signals suggest that vocalization plays an important role in the subterranean life of the mole rat. [Supported by the National Science Foundation.]
Sonar Array Response to Ambient Noise Directional Fields, Comparing Numerical Results to Closed-Form Estimates
Authors: Burroughs C. B. , O'Connor J. C. P.
Published: May 2012

Several studies have been directed towards the development of both numerical and analytical expressions of ambient noise directionality. In this paper, the results of a simplified ambient noise model are employed to examine the response of sonar arrays to directional noise fields. Expressions are found for the array gain against a combination of distant shipping and wind noise employing vertical and horizontal line arrays as examples. The results are compared in each case with array gain against isotropic noise (i.e., directivity index). Array response is found as a function of array orientation, frequency (or size), and steering angle. For the broadside steered line array, a simplified beam response pattern is used to find array gain for these simple analytical noise models. Results compare very well with array gains computed using more precise models of the ambient noise field and exact array response patterns. The implications on sonar design and performance studies are discussed, as well as similar estimates for the response of more complex array configurations. [Study supported by NAVSHIPS, PMS 302–44.]
Spatial Correlation in Arbitrary Noise Fields
Authors: Cox Henry
Published: May 2012

Explicit expressions are developed for the cross-spectral density between pairs of sensors and the wavenumber-frequency spectrum projected onto the line joining these sensors, when they are placed in arbitrary positions in noise fields which are described by an arbitrary directional distribution of uncorrelated plane waves. The approach is to expand the directional distribution in spatial harmonics. Each harmonic leads to a corresponding term, with the same coefficient, in series representations for the cross-spectral density function and the wavenumber-frequency spectrum. The approach is particularly attractive when the field can be adequately represented by a relatively small number of harmonics. Both two- and three-dimensional fields are considered. [This work was performed at the University of California, San Diego, Marine Physical Laboratory of the Scripps Institution of Oceanography, San Diego, California 92132.]
Bi-Dynamic Reverberation and Acoustic Field Reconstruction
Authors: Grace O. D. , Halley R.
Published: May 2012

A signal that is generated by a moving source is spatially encoded by both the angular dependent Doppler shift in frequency and the angular dependent beam patterns of the transmitter. This information is preserved in the resulting reverberation and it has been theorized [R. Halley, “An Application of the Analysis of Reverberation from a Remote Pinging Searchlight Sonar,” TM 262, Navy Electron. Lab., San Diego, Calif. (1957)] that it can be recovered by means of a spectral analysis of the reverberation that is collected by an arbitrarily positioned receiver. To investigate this theory a bi-dynamic model of reverberation has been developed that is based on the Poisson distributed discrete scatterer model of Faure, Olshevski, and Middleton. The correlation function of the reverberation field was developed for various cases and the corresponding time-dependent power spectra have been computed. Certain of these results have been compared with data that were collected at sea.
Partial Recovery of Loss of Array Gain due to Quantization in Digital Beamformers by Post Filtering
Authors: Wang H. S. C.
Published: May 2012

By assuming a sinusoidal wave embedded in Gaussian noise as array input signal, the output autocorrelation function of a digital beamformer can be expressed as the sum of infinite series Rsxs, Rnxn, and Rsxn, involving signal and its harmonics, ascending powers of noise cross-correlation functions, and “quantizer functions” of various orders [H. S. C. Wang, J. Acoust. Soc. Am. 53, 929 (1973)]. It is demonstrated that the effect of bandpass filtering of post-beamforming signal can be rigorously analyzed, without transforming to the frequency domain, by applying certain factors attributed first to Davenport [W. B. Davenport, Jr., J. Appl. Phys. 24, 702 (1953)] to the successive terms of the series Rnxk and Rsxn-In the special case of DIMUS processor, the series of quantizer functions reduce exactly to Davenport's confluent hyper-geometric series for his “bandpass rooter” with n → ∞. For a 12-channel beamformer, the array gain improvement or partial recovering of quantizing (clipping) loss by post filtering in correlated and uncorrelated noise fields at different values of input SNR is numerically evaluated and displayed.
The Effect of Nonstationary Parameters on the Estimates to the Multiple Transfer Function and Partial Coherency Function
Authors: Schmid C. E.
Published: May 2012

A linear system consisting of two inputs and one output was simulated on a digital computer. The model for the simulation was based upon two accelerometer inputs monitored aboard a ship and one farfield hydrophone output receiving radiated and ambient noise. The ultimate goal of the analysis is to evaluate the individual effect of each of the accelerometer inputs on the single hydrophone output. Sinusodal signals and second-order autoregressive Gaussian noise processes were generated for the computer simulation. The frequency of the sinusoid was deterministically varied with time. Estimates to the spectra, multiple and partial coherencies, and transfer functions were calculated by averaging overlapped periodograms. The bias and variance of these estimates resulting from varying the frequency with time and overlapping periodograms were measured and will be presented.
A Method for Estimating the Audibility and Effective Loudness of Speech and Warning Signals in Moving Vehicles
Authors: Corliss E. L. R. , Jones F. E.
Published: May 2012

By using the parameters for the ear and the equations for a “communication theory” model of the behavior of the ear, a family of curves can be set up for the performance of the ear under masking conditions, such as those prevalent in automotive vehicles. From the ability of the ear to recognize sounds in noise, estimates can be made for the conditions under which sirens and communications will be audible within motor vehicles moving in traffic, and some estimate can also be made as to their potential for attracting notice. These quantities may be read off by graphic techniques. Examples of their use are given.
A Unique Method to Measure the Sound Absorption Coefficient for Oblique Incidence
Authors: Vér I. L.
Published: May 2012

The method requires subsequent accurate recording of the absolute value of the transfer function between omnidirectional sound source and microphone in an anechoic environment for three configurations: (1) without the sample or barrier, (2) without the sample but with a barrier blocking the line of sight between source and receiver, and (3) with both the barrier and the sample in place. The first two recordings “calibrate” the barrier, while the second and third provide an interference pattern between the sound refracted around the edge of the barrier and that reflected from the sample. The reflection factor given as |R(f)| = d3d1 |p2(f)||p1(f)| |1 − |p3(f)||p2(f)|| must be evaluated at the frequencies of the minima and maxima of the interference pattern. d3/d1 is the ratio of the path lengths of the reflected and direct signal, p1/p2 is the insertion loss of the barrier, and p3 and p2 are the signals recorded with and without the sample in place, respectively. Experimental results on scale-model anechoic wedge surfaces are presented. [This study was sponsored by the NASA-Langley Research Center.]
Measurement of High-Frequency Absorption Coefficients
Authors: Rutledge James R.
Published: May 2012

A test set up to evaluate the high-frequency (2.5–20 kHz) random incidence absorption coefficients of various materials using the reverberation-chamber method is discussed. A small reverberant chamber (2.2 ft3), which has a lower limiting frequency of approximately 2 kHz, was built and used for the tests. The instrumentation system for measuring the very rapid decay rates involved is only briefly discussed. Since the primary interest was the effect of material surface texture on the absorption coefficients at 8 kHz and above, the necessary small sample size could be tolerated. The results of a few tests are also being discussed.
Adenosine A
2A
Receptor Activation Prevents Wear Particle–Induced Osteolysis
Authors: Mediero Aránzazu , Frenkel Sally R. , Wilder Tuere , He Wenjie , Mazumder Amitabha , Cronstein Bruce N.
Published: May 2012

An adenosine A
2A
receptor agonist prevents osteolysis caused by polymeric wear particles in mouse calvaria.
PTH/PTHrP and Vitamin D Control Antimicrobial Peptide Expression and Susceptibility to Bacterial Skin Infection
Authors: Muehleisen Beda , Bikle Daniel D. , Aguilera Carlos , Burton Douglas W. , Sen George L. , Deftos Leonard J. , Gallo Richard L.
Published: May 2012

Vitamin D and parathyroid hormone work together to maximize innate immune resistance to skin infections.
TB and HIV: Deadly Liaison or Manageable Threat?
Authors: Williams Brian G.
Published: May 2012

Dynamical models throw light on the complex relationship between HIV and drug-resistant TB.
Abandonment Complexes
Authors: Collier Joel H.
Published: May 2012

Nanoparticle carriers can solve some problems associated with drugs that have failed to progress in clinical development.
A New Risk Factor for Autism?
Authors: Reznik Marina
Published: May 2012

An X-linked inborn error of carnitine metabolism may be a risk factor for autism.
Trends in cardiovascular disease biomarkers and their socioeconomic patterning among adults in the Scottish population 1995 to 2009: cross-sectional surveys
Authors: Hotchkiss Joel William , Davies Carolyn Anne , Gray Linsay , Bromley Catherine , Capewell Simon , Leyland Alastair
Published: May 2012

Objectives

To examine secular and socioeconomic changes in biological cardiovascular disease risk factor and biomarker prevalences in the Scottish population. This could contribute to an understanding of why the decline in coronary heart disease mortality in Scotland has recently stalled along with persistence of associated socioeconomic inequalities.

Design

Cross-sectional surveys.

Setting

Scotland.

Participants

Scottish Health Surveys: 1995, 1998, 2003, 2008 and 2009 (6190, 6656, 5497, 4202 and 4964 respondents, respectively, aged 25–64 years).

Primary outcome measures

Gender-stratified, age-standardised prevalences of obesity, hypertension, hypercholesterolaemia and low high-density lipoprotein cholesterol blood concentration as well as elevated fibrinogen and C reactive protein concentrations according to education and social class groupings. Inequalities were assessed using the slope index of inequality, and time trends were assessed using linear regression.

Results

The prevalence of obesity, including central obesity, increased between 1995 and 2009 among men and women, irrespective of socioeconomic position. In 2009, the prevalence of obesity (defined by body mass index) was 29.8% (95% CI 27.9% to 31.7%) for men and 28.2% (26.3% to 30.2%) for women. The proportion of individuals with hypertension remained relatively unchanged between 1995 and 2008/2009, while the prevalence of hypercholesterolaemia declined in men from 79.6% (78.1% to 81.1%) to 63.8% (59.9% to 67.8%) and in women from 74.1% (72.6% to 75.7%) to 66.3% (62.6% to 70.0%). Socioeconomic inequalities persisted over time among men and women for most of the biomarkers and were particularly striking for the anthropometric measures when stratified by education.

Conclusions

If there are to be further declines in coronary heart disease mortality and reduction in associated inequalities, then there needs to be a favourable step change in the prevalence of cardiovascular disease risk factors. This may require radical population-wide interventions.
Are they half as strong as they used to be? An experiment testing whether age-related social comparisons impair older people's hand grip strength and persistence
Authors: Swift Hannah J , Lamont Ruth A , Abrams Dominic
Published: May 2012

Objective

To assess how age-related social comparisons, which are likely to arise inadvertently or deliberately during assessments, may affect older people's performance on tests that are used to assess their needs and capability.

Design

The study randomly assigned participants to a comparison with younger people or a no comparison condition and assessed hand grip strength and persistence. Gender, education, type of residence, arthritis and age were also recorded.

Setting

Age UK centres and senior's lunches in the South of England.

Participants

An opportunity sample of 56 adults, with a mean age of 82.25 years.

Main outcomes measures

Hand grip strength measured using a manual hand dynamometer and persistence of grip measured using a stopwatch.

Results

Comparison caused significantly worse performance measured by both strength (comparison =6.85 kg, 95% CI 4.19 kg to 9.5 kg, control group =11.07 kg, 95% CI 8.47 kg to 13.68 kg, OR =0.51, p=0.027) and persistence (comparison =8.36 s, 95% CI 5.44 s to 11.29 s; control group =12.57 s, 95% CI 9.7 s to 15.45 s, OR =0.49, p=0.045). These effects remained significant after accounting for differences in arthritis, gender, education and adjusting for population age norms.

Conclusions

Due to the potential for age comparisons and negative stereotype activation during assessment of older people, such assessments may underestimate physical capability by up to 50%. Because age comparisons are endemic, this means that assessment tests may sometimes seriously underestimate older people's capacity and prognosis, which has implications for the way healthcare professionals treat them in terms of autonomy and dependency.
Birth outcomes for African and Caribbean babies in England and Wales: retrospective analysis of routinely collected data
Authors: Datta-Nemdharry Preeti , Dattani Nirupa , Macfarlane Alison J
Published: May 2012

Objectives

To compare mean birth weights, gestational ages and odds of preterm birth and low birth weight of live singleton babies of black African or Caribbean ethnicity born in 2005 or 2006 by mother's country of birth.

Design

Secondary analysis of data from linked birth registration and NHS Numbers for Babies data set.

Setting

Births to women in England and Wales in 2005 and 2006.

Participants

Babies of African and Caribbean ethnicity born in England and Wales in 2005–2006, whose mothers were born in African and Caribbean countries or the UK. Birth outcomes for 51 599 singleton births were analysed.

Main outcome measures

Gestational age and birth weight.

Results

Mothers born in Eastern or Northern Africa had babies at higher mean gestational ages (39.38 and 39.41 weeks, respectively) and lower odds of preterm birth (OR=0.80 and 0.65, respectively) compared with 39.00 weeks for babies with mothers born in the UK. Babies of African ethnicity whose mothers were born in Middle or Western Africa had mean birth weights of 3327 and 3311 g, respectively. These were significantly higher than the mean birth weight of 3257 g for babies of the UK-born mothers. Their odds of low birth weight (OR=0.75 and 0.72, respectively) were significantly lower. Babies of Caribbean ethnicity whose mothers were born in the Caribbean had higher mean birth weight and lower odds of low birth weight than those whose mothers were born in the UK.

Conclusions

The study shows that in babies of African and Caribbean ethnicity, rates of low birth weight and preterm birth varied by mothers' countries of birth. Ethnicity and country of birth are important factors associated with perinatal health, but assessing them singly can mask important heterogeneity in birth outcomes within categories particularly in relation to African ethnicity. These differences should be explored further.
The hyperdense vessel sign on CT predicts successful recanalization with the Merci device in acute ischemic stroke
Authors: Froehler Michael T , Tateshima Satoshi , Duckwiler Gary , Jahan Reza , Gonzalez Nestor , Vinuela Fernando , Liebeskind David , Saver Jeffrey L , Villablanca J Pablo ,   For the UCLA Stroke Investigators
Published: May 2012

Background

The success of mechanical clot retrieval for acute ischemic stroke may be influenced by the characteristics of the occlusive thrombus. The thrombus can be partly characterized by CT, as the hyperdense vessel sign (HVS) suggests erythrocyte-rich clot whereas fibrin-rich clot may be isodense. We hypothesized that the physical clot characteristics that determine CT density may also determine likelihood of retrieval with the Merci device.

Methods

We reviewed all acute stroke cases initially imaged with non-contrast CT before attempted Merci clot retrieval at a single center between 2004 and 2010. Each CT was blindly assessed for the presence or absence of the HVS, and post-retrieval angiograms were blindly assessed for reperfusion using the TICI scale.

Results

Of 67 patients analyzed (mean age 69; median NIHSS 19; 61% female), the HVS was seen in 42, and no HVS was present in 25. Successful recanalization was achieved in 79% of patients with the HVS (33/42), but in only 36% (9/25) of patients without HVS (p=0.001). The HVS was the only significant predictor of recanalization while accounting for age, treatment with IV-tPA, clot location, stroke etiology, time to treatment, and number of retrieval attempts.

Conclusion

The HVS in acute ischemic stroke was strongly predictive of successful recanalization using the Merci device. The HVS may indicate thrombi that are less adhesive compared with isodense clots that are more resistant to mechanical retrieval. The absence of HVS on pre-treatment CT may thus suggest the need for a more aggressive or alternative therapeutic approach.
Pathologic validation of clot length determined using thin section non-contrast CT
Authors: Yoo Albert J , Leslie-Mazwi Thabele M , Riedel Christian H , Chandra Ronil V
Published: May 2012

Background and purpose

Recent studies have demonstrated that in acute ischemic stroke patients, thin section non-contrast CT (NCCT) can be used to determine the length of the hyperdense intracranial thrombus, and that clot length using this approach predicts the likelihood of vessel recanalization after intravenous tissue plasminogen activator.

Summary of case

An acute ischemic stroke patient presented with a left middle cerebral artery occlusion and underwent emergent catheter based therapy. Clot length was determined using pretreatment thin section NCCT and was independently confirmed by the pathologist after whole clot extraction.

Conclusions

The concordance between the NCCT measured clot length and the pathological examination in this case provides additional support for the accuracy of using thin section NCCT data to determine clot length in all patients.
Image registration for foveated panoramic sensing
Authors: Dornaika Fadi , Elder James H.
Published: May 2012

This article addresses the problem of registering high-resolution, small field-of-view images with low-resolution panoramic images provided by a panoramic catadioptric video sensor. Such systems may find application in surveillance and telepresence systems that require a large field of view and high resolution at selected locations. Although image registration has been studied in more conventional applications, the problem of registering panoramic and conventional video has not previously been addressed, and this problem presents unique challenges due to (i) the extreme differences in resolution between the sensors (more than a 16:1 linear resolution ratio in our application), and (ii) the resolution inhomogeneity of panoramic images. The main contributions of this article are as follows. First, we introduce our foveated panoramic sensor design. Second, we show how a coarse registration can be computed from the raw images using parametric template matching techniques. Third, we propose two refinement methods allowing automatic and near real-time registration between the two image streams. The first registration method is based on matching extracted interest points using a closed form method. The second registration method is featureless and based on minimizing the intensity discrepancy allowing the direct recovery of both the geometric and the photometric transforms. Fourth, a comparison between the two registration methods is carried out, which shows that the featureless method is superior in accuracy. Registration examples using the developed methods are presented.
Comparison of predictive contract mechanisms from an information theory perspective
Authors: Zhang Xin , Ward Tomás , Mcloone Séamus
Published: May 2012

Inconsistency arises across a Distributed Virtual Environment due to network latency induced by state changes communications. Predictive Contract Mechanisms (PCMs) combat this problem through reducing the amount of messages transmitted in return for perceptually tolerable inconsistency. To date there are no methods to quantify the efficiency of PCMs in communicating this reduced state information. This article presents an approach derived from concepts in information theory for a deeper understanding of PCMs. Through a comparison of representative PCMs, the worked analysis illustrates interesting aspects of PCMs operation and demonstrates how they can be interpreted as a form of lossy information compression.
Approaches to Exploring Category Information for Question Retrieval in Community Question-Answer Archives
Authors: Cao Xin , Cong Gao , Cui Bin , Jensen Christian S. , Yuan Quan
Published: May 2012

Community Question Answering (CQA) is a popular type of service where users ask questions and where answers are obtained from other users or from historical question-answer pairs. CQA archives contain large volumes of questions organized into a hierarchy of categories. As an essential function of CQA services, question retrieval in a CQA archive aims to retrieve historical question-answer pairs that are relevant to a query question. This article presents several new approaches to exploiting the category information of questions for improving the performance of question retrieval, and it applies these approaches to existing question retrieval models, including a state-of-the-art question retrieval model. Experiments conducted on real CQA data demonstrate that the proposed techniques are effective and efficient and are capable of outperforming a variety of baseline methods significantly.
A Probabilistic Model to Combine Tags and Acoustic Similarity for Music Retrieval
Authors: Miotto Riccardo , Orio Nicola
Published: May 2012

The rise of the Internet has led the music industry to a transition from physical media to online products and services. As a consequence, current online music collections store millions of songs and are constantly being enriched with new content. This has created a need for music technologies that allow users to interact with these extensive collections efficiently and effectively. Music search and discovery may be carried out using tags, matching user interests and exploiting content-based acoustic similarity. One major issue in music information retrieval is how to combine such noisy and heterogeneous information sources in order to improve retrieval effectiveness. With this aim in mind, the article explores a novel music retrieval framework based on combining tags and acoustic similarity through a probabilistic graph-based representation of a collection of songs. The retrieval function highlights the path across the graph that most likelyobservesa user query and is used to improve state-of-the-art music search and discovery engines by delivering more relevant ranking lists. Indeed, by means of an empirical evaluation, we show how the proposed approach leads to better performances than retrieval strategies which rank songs according to individual information sources alone or which use a combination of them.
Exploring Question Selection Bias to Identify Experts and Potential Experts in Community Question Answering
Authors: Pal Aditya , Harper F. Maxwell , Konstan Joseph A.
Published: May 2012

Community Question Answering (CQA) services enable their users to exchange knowledge in the form of questions and answers. These communities thrive as a result of a small number of highly active users, typically calledexperts, who provide a large number of high-quality useful answers. Expert identification techniques enable community managers to take measures to retain the experts in the community. There is further value in identifying the experts during the first few weeks of their participation as it would allow measures to nurture and retain them. In this article we address two problems: (a) How to identify current experts in CQA? and (b) How to identify users who have potential of becoming experts in future (potential experts)? In particular, we propose a probabilistic model that captures the selection preferences of users based on the questions they choose for answering. The probabilistic model allows us to run machine learning methods for identifying experts and potential experts. Our results over several popular CQA datasets indicate that experts differ considerably from ordinary users in their selection preferences; enabling us to predict experts with higher accuracy over several baseline models. We show that selection preferences can be combined with baseline measures to improve the predictive performance even further.
Predicting Query Performance by Query-Drift Estimation
Authors: Shtok Anna , Kurland Oren , Carmel David , Raiber Fiana , Markovits Gad
Published: May 2012

Predicting
query performance
, that is, the effectiveness of a search performed in response to a query, is a highly important and challenging problem. We present a novel approach to this task that is based on measuring the standard deviation of retrieval scores in the result list of the documents most highly ranked. We argue that for retrieval methods that are based on document-query surface-level similarities, the standard deviation can serve as a surrogate for estimating the presumed amount of
query drift
in the result list, that is, the presence (and dominance) of aspects or topics not related to the query in documents in the list. Empirical evaluation demonstrates the prediction effectiveness of our approach for several retrieval models. Specifically, the prediction quality often transcends that of current state-of-the-art prediction methods.
Authorship Attribution Based on Specific Vocabulary
Authors: Savoy Jacques
Published: May 2012

In this article we propose a technique for computing a standardized Z score capable of defining the specific vocabulary found in a text (or part thereof) compared to that of an entire corpus. Assuming that the term occurrence follows a binomial distribution, this method is then applied to weight terms (words and punctuation symbols in the current study), representing the lexical specificity of the underlying text. In a final stage, to define an author profile we suggest averaging these text representations and then applying them along with a distance measure to derive a simple and efficient authorship attribution scheme. To evaluate this algorithm and demonstrate its effectiveness, we develop two experiments, the first based on 5,408 newspaper articles (Glasgow Herald) written in English by 20 distinct authors and the second on 4,326 newspaper articles (La Stampa) written in Italian by 20 distinct authors. These experiments demonstrate that the suggested classification scheme tends to perform better than the Delta rule method based on the most frequent words, better than the chi-square distance based on word profiles and punctuation marks, better than the KLD scheme based on a predefined set of words, and better than the naïve Bayes approach.
USACM and U.S. legislation
Authors: Spafford Eugene H.
Published: May 2012

Computing professionals sometimes find policy issues ill-defined, confusing, or irrelevant. Perhaps that is why---to date---policy participation has been limited within our community.
A guided tour of data-center networking
Authors: Abts Dennis , Felderman Bob
Published: May 2012

A good user experience depends on predictable performance within the data-center network.
Real-time computer vision with OpenCV
Authors: Pulli Kari , Baksheev Anatoly , Kornyakov Kirill , Eruhimov Victor
Published: May 2012

Mobile computer-vision technology will soon become as ubiquitous as touch interfaces.
Data services
Authors: Carey Michael J. , Onose Nicola , Petropoulos Michalis
Published: May 2012

Exploring the technology trends in basic, integrated, and cloud data services.
Exact matrix completion via convex optimization
Authors: Candès Emmanuel , Recht Benjamin
Published: May 2012

Suppose that one observes an incomplete subset of entries selected from a low-rank matrix. When is it possible to complete the matrix and recover the entries that have not been seen? We demonstrate that in very general settings, one can perfectly recover all of the missing entries from most sufficiently large subsets by solving a convex programming problem that finds the matrix with the minimum nuclear norm agreeing with the observed entries. The techniques used in this analysis draw upon parallels in the field of compressed sensing, demonstrating that objects other than signals and images can be perfectly reconstructed from very limited information.
Report on TBAS 2012
Authors: Larsen Birger , Lioma Christina , de Vries Arjen
Published: May 2012

The ECIR half-day workshop on Task-Based and Aggregated Search (TBAS) was held in Barcelona, Spain on 1 April 2012. The program included a keynote talk by Professor Järvelin, six full paper presentations, two poster presentations, and an interactive discussion among the approximately 25 participants. This report overviews the aims and contents of the workshop and outlines the major outcomes.
Nicorandil, a Katp channel opener, alleviates chronic renal injury by targeting podocytes and macrophages
Authors: Tamura Yoshifuru , Tanabe Katsuyuki , Kitagawa Wataru , Uchida Shunya , Schreiner George F. , Johnson Richard J. , Nakagawa Takahiko
Published: May 2012

Nicorandil exhibits a protective effect in the vascular system, which is thought to be due to vasodilatation from opening ATP-dependent potassium channels and donation of nitric oxide. Recently, nicorandil was shown to be renoprotective in models of acute kidney injury and glomerulonephritis. However, the specific mechanisms of renoprotection are unclear. We evaluated the effect of nicorandil on the rat remnant kidney model of chronic kidney disease. Blood pressure was unchanged by a 10-wk course of nicorandil, while albuminuria was significantly reduced. Glomerular injury and tubulointerstitial injury were also ameliorated by nicorandil. Oxidative stress, as noted by renal nitrotyrosine level and urine 8-hydroxy-2′-deoxyguanosine, were elevated in this model and was significantly reduced by nicorandil treatment. Treatment was associated with maintenance of the mitochondrial antioxidant, manganese SOD, in podocytes and with suppression of xanthine oxidase expression in infiltrating macrophages. Interestingly, these two cell types express sulfonylurea receptor 2 (SUR2), a binding site of nicorandil in the ATP-dependent K channel. Consistently, we found that stimulating SUR2 with nicorandil prevented angiotensin II-mediated upregulation of xanthine oxidase in the cultured macrophage, while xanthine oxidase expression was rather induced by blocking SUR2 with glibenclamide. In conclusion, nicorandil reduces albuminuria and ameliorates renal injury by blocking oxidative stress in chronic kidney disease.