bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of temporal position, proportional variance, and proportional duration on decision weights in temporal pattern discrimination
Authors: Sadralodabai Toktam , Sorkin Robert D.
Published: July 2002

Two experiments investigated how listeners allocate their attention to different segments of a temporal pattern. The experiments allowed a direct test of the predictions of the Proportion of Total Duration (PTD) rule and the Component Relative Entropy (CoRE) model. Listeners had to decide whether two sequences of nine tones had the same or different temporal patterns (tone duration=25 ms, tone frequency=1000 Hz). A sequence’s temporal pattern was determined by the time intervals between each tone’s offset and the next tone’s onset. On same trials, the time intervals at corresponding temporal positions in the two sequences were identical. On different trials, the corresponding time intervals were randomly varied. Listener attention to different temporal positions within a sequence was assessed by calculating the decision weights at each position. The results supported the CoRE model and were inconsistent with the PTD rule. Manipulating the mean of the time intervals within the sequence had no consistent effect on the pattern of weights (or on overall performance), indicating that listener attention was not affected by either the proportion of total duration or the perceptual salience of a longer or shorter time interval. However, manipulating the variance of the time intervals had a significant effect: the highest weight was given to the highest variance segment. This weighting strategy leads to better performance because higher variance segments are more diagnostic of whether the sequences are the same or different.
Computer-aided systems for prolonged recording and analysis of human bowel sounds
Authors: Dimoulas Charalambos A. , Papanikolaou George V. , Kalliris George M. , Pastiadis Costas
Published: July 2002

This paper presents the design of noninvasive systems for the investigation of the small bowel motility patterns. The basic idea was to implement dedicated devices for the recording and analysis of human bowel sounds. Properly modified transducers were used for the caption of gastrointestinal sound signals. A data acquisition ambulatory system, consisting of a preamplifier and a recording unit, was initially designed capable for maximum continuous recording of 6 h. After the first experimental results with this system, the necessity for longer recording duration was obvious. For this reason the installation of a computer-based stationary system in a special reformed examination room was the next development step. Triggering of the input data and rejection of the regions with absence of gastrointestinal activity allowed much more recording duration. A computerized signal processing system, which involves equalizing procedures, noise cancellation techniques, and neural network algorithms, was used for the off-line analysis of the recorded data. Novel measures and 2-D and 3-D representation techniques were employed for the exposition of results. The new approach gave flexibility to the system because longer recording times offer more information to the doctor so that the statistical analysis is much more effective and reliable.
Eigenforms and eigenfrequency spectrum of finite elastic cylinder
Authors: Grinchenko Victor T.
Published: July 2002

The reflection of elastic waves from free boundaries is accompanied by the effects of transformation of longitudinal waves to transverse ones and vice versa. The transformation is the physical basis for interesting and practically important peculiarities in eigenfrequency spectrum and characteristics of eigenforms. The cases of finite cylinder (RL) are considered to illustrate these peculiarities. The main idea of the boundary problem solution method is described. The method provides a way to get the eigenmode characteristics accurately in a wide-frequency range. The general conclusion of the study is that it is not possible to give a qualitative explanation of the eigenfrequency spectrum and eigenform properties in the scope of the concept of standing waves with respect to propagating ones in long elastic cylinder and infinite layer. The special propagating evanescent waves are important in the eigenmode forming process. The influence of this kind of wave results, for example, in occurrence of eigenfrequencies value, which increases when dimensions of the cylinder increase. Specific features of corresponding eigenforms are discussed. Comparison of the numerical and experimental data is presented.
Reduction of the performance of a noise screen due to screen-induced wind-speed gradients. Numerical computations and wind-tunnel experiments
Authors: Salomons Erik M.
Published: July 2002

Downwind sound propagation over a noise screen is investigated by numerical computations and scale model experiments in a wind tunnel. For the computations, the parabolic equation method is used, with a range-dependent sound-speed profile based on wind-speed profiles measured in the wind tunnel and wind-speed profiles computed with computational fluid dynamics (CFD). It is found that large screen-induced wind-speed gradients in the region behind the screen are responsible for a considerable reduction of the performance of the screen, for receivers near the boundary of the shadow region behind the screen. The screen-induced wind-speed gradients cause a considerable reduction of the size of the shadow region. If the screen-induced wind-speed gradients are taken into account, computed sound-pressure levels near the shadow boundary are in reasonable agreement with levels measured in the wind tunnel. In contrast, computed levels are considerably lower, up to 10 dB, if the screen-induced wind-speed gradients are ignored. This implies that the performance of a screen can be considerably improved if the screen-induced wind-speed gradients can be suppressed, e.g., by the use of “vented” screens.
Waves in rotating conducting piezoelectric media
Authors: Wauer J.
Published: July 2002

The propagation of waves in a conducting piezoelectric solid is studied for the case when the entire medium rotates with a uniform angular velocity. For comparison, both the conventional electrically quasistatic theory and the fully dynamic Maxwell equations are taken into consideration. In completion, a generalized thermoelastic theory of piezoelectric bodies is incorporated. The governing dispersion relations are obtained to determine the effects of moderate rotation, thermal, and constant electrical conductivity on the finite phase velocity of the waves. Analysis is carried out for plane waves in an infinite medium but also for surface waves of a half-space. Finally, the radial vibrations of a hollow cylinder are addressed. The evaluations are specified for hexagonal crystals of (6 mm) class and a simple arrangement of the direction of wave propagation and the crystal and rotational axes.
Active control of fan tones radiated from turbofan engines. I. External error sensors
Authors: Joseph P. , Nelson P. A. , Fisher M. J.
Published: July 2002

This paper is the first of two papers dealing with the active control of fan tones radiated from the intake of turbofan engines. The present paper describes an idealized mathematical model for the prediction of the sound transmission and radiation of harmonic sound from a finite-length, unflanged hollow hard-walled circular duct containing a subsonic axial mean flow. The paper proceeds to use this model in computer simulations aimed at assessing the potential for reducing the far-field radiated sound by active means using two rings of discrete secondary sources on the duct wall. Perfect knowledge of the sound field to be controled is assumed throughout. The paper investigates two control objectives. The first is concerned with minimizing the total sound power transmitted along the duct, and hence the total sound power radiated. The other is concerned with minimizing the radiated sound power radiated into a specified band of sideline solid angles. Implicit in this investigation is the assumption of perfect observability of the radiated far field equivalent to a large number of error sensors located in the far field. The corresponding performance for the two control objectives when the observability of the sound field is limited to measurements made by a number of the error sensors situated on the duct wall is the subject of the companion paper.
The effect of age on temporal integration
Authors: Gehr Sara Elizabeth , Sommers Mitchell S.
Published: July 2002

The present study was designed to assess the effects of age, independent of hearing loss, on temporal integration of sinusoidal signals. Thresholds for detecting a 1000-Hz sinusoid as a function of signal duration were measured for signal durations ranging from 20–500 ms. The signal had a rise/fall time of 10 ms. Subjects were younger (18–22) and older (over age 65) adults with normal hearing (thresholds less than 20 dB HL) for frequencies of 4 kHz and below. At the shortest signal duration (20 ms), thresholds for both groups were elevated approximately 16 dB relative to their thresholds for the 500-ms signal. Both older and younger adults also exhibited similar decreases in threshold as a function of signal duration. Overall, the findings suggest that unlike most temporally based psychoacoustic tasks, temporal integration of sinusoids remains relatively unchanged as a function of age.
An experimental verification of Rayleigh’s interpretation of the Sondhauss tube
Authors: Huelsz Guadalupe , Ramos Eduardo
Published: July 2002

The interaction of a sound wave in a compressible fluid in contact with solid boundaries produces thermoacoustic effects. A century ago, Lord Rayleigh gave a general qualitative explanation of the acoustic power production by unsteady heat transfer to compressible fluid in terms of the relative phase of the pressure wave and the heat transferred to the fluid. In quantitative terms his interpretation is equivalent to saying that a wave is promoted if the absolute value of this relative phase is less than π/2; otherwise the wave is attenuated. In this paper, an experimental investigation of the attenuation or promotion of an acoustic wave as a function of an axial temperature gradient at the wall of the waveguide is presented. Using the techniques previously developed [J. Acoust. Soc. Am. 103, 1532–1537 (1998)], acoustic temperature and pressure oscillations measurements in the thermal boundary layer of an acoustic standing wave in air were made. The results reported here experimentally confirm the validity of Rayleigh’s interpretation of the power production for this case. This confirmation is more direct than any previous evidence.
Dependence of binaural masking level differences on center frequency, masker bandwidth, and interaural parameters
Authors: van de Par Steven , Kohlrausch Armin
Published: July 2002

Thresholds for sinusoidal signals masked by noise of various bandwidths were obtained for three binaural configurations: N0S0 (both masker and signal interaurally in phase), N0Sπ (masker interaurally in phase and signal interaurally phase-reversed), and NπS0 (masker interaurally phase-reversed and signal interaurally in phase). Signal frequencies of 125, 250, 500, 1000, 2000, and 4000 Hz were combined with masker bandwidths of 5, 10, 25, 50, 100, 250, 500, 1000, 2000, 4000, and 8000 Hz, with the restriction that masker bandwidths never exceeded twice the signal frequency. The overall noise power was kept constant at 70 dB SPL for all bandwidths. Results, expressed as signal-to-total-noise power ratios, show that N0S0 thresholds generally decrease with increasing bandwidth, even for subcritical bandwidths. Only at frequencies of 2 and 4 kHz do thresholds appear to remain constant for bandwidths around the critical bandwidth. N0Sπ thresholds are generally less dependent on bandwidth up to two or three times the (monaural) critical bandwidth. Beyond this bandwidth, thresholds decrease with a similar slope as for the N0S0 condition. NπS0 conditions show about the same bandwidth dependence as N0Sπ, but thresholds in the former condition are generally higher. This threshold difference is largest at low frequencies and disappears above 2 kHz. An explanation for wider operational binaural critical bandwidth is given which assumes that binaural disparities are combined across frequency in an optimally weighted way.
Modeling vibration and sound production in insects with nonresonant stridulatory organs
Authors: Tschuch Gunther , Brothers Denis J.
Published: July 2002

Using a simple model for a nonresonant stridulatory organ, the intensities and shapes of the vibrations produced and the radiated sound were calculated. To test the results, the stridulation of femal multillid wasps (Mutillidae, Hymenoptera, Insecta) was investigated by the help of sound-analytical methods and with laser vibrometry. The model was shown to give good estimations for the sound spectrum and for the absolute power of the second to fifth harmonics. The wasps investigated, females of Dasylabris maura and “Smicromyrme” praedatrix with body lengths of about 10 mm, are able to make audible sounds with a power level of about 40 dB at a distance of 0.1 m. Stridulatory organs like those in mutillid wasps occur in several species of insects (e.g., beetles, wasps, and ants) and in other arthropods.
On array design for matched-field processing
Authors: Tantum Stacy L. , Nolte Loren W.
Published: July 2002

Conventional plane-wave beamforming array design guidelines are motivated by the desire to obtain particular beampattern characteristics, such as main lobe width and side lobe levels. These design guidelines are appropriate for arrays employed for beamforming, where a plane-wave signal model is utilized to derive both the array design parameters and the beamforming algorithm. However, matched-field processing utilizes full-field acoustic propagation models to exploit the complexities of ocean acoustic propagation. As a result, there may be more appropriate design guidelines for arrays employed for matched-field processing. In this paper, general guidelines for matched-field processing array design utilizing a normal mode propagation model are proposed. Various line array configurations are evaluated with respect to source localization performance, and the results suggest that arrays designed for matched-field processing should provide a unique representation of each propagating mode along the extent of the array. Further, the empirical analyses support the guidelines suggested by the theoretical analyses and show that arrays which are far from meeting conventional beamforming array design requirements may be more than sufficient for matched-field processing.
Experimental investigation of the pulse inversion technique for imaging ultrasound contrast agents
Authors: Verbeek Xander A. A. M. , Ledoux Léon A. F. , Willigers Jean M. , Brands Peter J. , Hoeks Arnold P. G.
Published: July 2002

The application of ultrasound contrast agents aims to detect low velocity blood flow in the microcirculation. To enhance discrimination between tissue and blood containing the contrast agent, harmonic imaging is used. Harmonic imaging requires the application of narrow-band signals and is obscured by high levels of native harmonics generated in an intervening medium. To improve discrimination between contrast agent and native harmonics, a pulse inversion technique has been proposed. Pulse inversion allows wide-band signals, thus preserving the axial resolution. The present study examines the interference of native harmonics and discusses the practical difficulties of wide-band pulse inversion measurements of harmonics by a single transducer. Native harmonics are not eliminated by pulse inversion. Furthermore, only even harmonics remain and are amplified by 6 dB, alleviating the requirement for selective filtering. Finally, it is shown that the contaminating third harmonic contained in the square wave activation signal leaks through in the emitted signal. The spectral location of the contaminating third harmonic is governed by the transducer spectral characteristics while the location of the native and contrast agent second harmonics is not. Thus the contarninating third harmonic and the native and contrast agent second harmonics may overlap and interfere. Optimal discrimination requires a balance between maximal sensitivity for the second harmonic at reception and minimal interference from the contaminating third harmonic.
Variability in the characterization of the headphone transfer-function
Authors: Kulkarni Abhijit , Colburn H. Steven
Published: July 2002

In simulations of virtual acoustic space, stimuli are filtered with HRTFs and presented over headphones. An equalization filter is specified to compensate for the spurious coloration introduced by the headphone delivery system on the stimulus at the listener’s eardrum. The purpose of this letter is to report the variability in the response of supra-aural headphones arising from the positioning of the headphone cushion during normal usage. The headphone responses were obtained on the KEMAR acoustical mannequin. It is shown that the variability in the measurements due to headphone cushion placements makes it difficult to specify a compensation filter for canceling the headphone characteristics. This makes the stimulus waveform at a listener’s eardrum unpredictable and could have an important consequence on the perceptual adequacy of virtual displays.
Frequency responses of two- and three-tone distortion product otoacoustic emissions in Mongolian gerbils
Authors: Mills David M.
Published: July 2002

The frequency responses of distortion product otoacoustic emission (DPOAEs) were investigated in adult Mongolian gerbils. The main goal was to investigate in this species the extent to which DPOAE measurements might be useful in estimating cochlear frequency-tuning characteristics. Specifically, this study investigated the parameter space for generation of DPOAEs to determine those regions, if any, where the emission responses gave “simple” frequency responses, i.e., responses similar in form to typical neural responses. At the same time, it was desired to determine in this species the existence, extent, and nature of the more complex three-tone emission frequency responses as observed in some other species [e.g., Martin et al., Hearing Res. 136, 105–123 (1999)]. In the present work, two-tone frequency response curves (f2/f1 ratio functions) were obtained by varying the lower frequency, f1, while holding the f2 frequency and both amplitudes (L1,L2) constant. Only for frequencies, f2, near 8 kHz did the response at the emission frequency, 2 f1–f2, form a simple, relatively broad peak. At all lower frequencies, the two-tone frequency response curve was typically complex and composed of multiple peaks. In comparison, three-tone frequency responses were constructed by fixing the primary stimulus pair (f1,f2) and varying a third tone widely in frequency (f3) and intensity (L3). Points in f3 and L3 which caused a criterion reduction in primary emission amplitude (at 2 f1–f2) were used to construct emission suppression tuning curves (STCs). Only for primary frequencies, f2, at 8 kHz and above were the emission STCs found to be simple, with shapes similar to neural frequency-tuning curves. At lower primary frequencies, particularly for relatively low primary frequency ratios (low f2/f1), three-tone responses were very complex. This complex response usually included a region of anomalous suppression in which very low suppression levels (L3) could result in significant decreases in the primary emission amplitude, often exceeding 12 dB. Regions of such anomalous suppression were typically observed under the following conditions: (1) for all f2 frequencies from 0.5 to 4 kHz; (2) for f3 frequencies between 1.4 and 8 kHz; (3) i.e., for f3 frequencies 1–3 octaves above the primary frequency, f2; (4) at L3 levels often 10 dB lower or more than the usual “best frequency” threshold, i.e., even lower than the relative minimum threshold found near the primary stimulus frequencies; (5) exhibiting sharp amplitude decreases often accompanied by emission phase shifts of about 180 deg; (6) present in both cubic emissions (2 f1–f2 and 2 f2–f1); (7) to be less extreme at larger primary stimulus frequency ratios (larger f2/f1); and (8) less extreme at larger intensity ratios (larger L1/L2). Because of the anomalous behavior at f2 frequencies below 8 kHz, “simple” emission STCs were typically only obtainable, if at all, near the extreme boundaries of the parameter space giving measurable emission amplitudes.
Blind deconvolution for multipath mitigation in shallow water acoustics
Authors: Smith George B.
Published: July 2002

Extraction of a signal received on a hydrophone array at tactical ranges in shallow water is made difficult by distortions caused by dynamic multipath. Blind deconvolution techniques can adapt the processing to the environment if reasonable assumptions about the nature of the Green’s functions used to represent the multipath propagation can be made. An interesting class of blind techniques is based on the fact that the desired signal is common to all channels, whereas the Green’s functions usually vary across channels. These techniques attempt to extract the desired source signal as the common factor among all data channels. Two techniques from this class are presented here: Rietsch’s algorithm, which is an exact algebraic solution to the blind deconvolution problem, and a method which attempts to derive filters that produce signal estimates from each data channel that are as consistent with each other as possible in a least squares sense. Using normalized correlations of output with ground truth as a performance measure, the performance of these two techniques will be compared to each other and to unprocessed output. [Work supported by ONR. Technical management was provided by the Naval Research Laboratory, Stennis Space Center, Mississippi.]
An EPG and acoustic study of fricative production and spectra
Authors: Tabain Marija
Published: July 2002

In order to test the correspondence between variability in fricative production and variability in the fricative spectrum, the spectral center of gravity (COG) is compared with the EPG center of gravity measured along the horizontal dimension. The CV coarticulatory effects in particular are examined. Data are taken from CV tokens produced by four female speakers of Australian English. Tokens consisted of the coronal fricatives /T s S D z Z/ in seven monophthong vowel contexts. Rounded vowels are excluded so as to minimize spectral changes due to lip-rounding. The consistency between the articulatory and the acoustic data is particularly striking for the palato-alveolar fricatives, although results are also highly consistent for the other two fricative places of articulation examined. However, it is not always clear that the variability in fricative production is conditioned by the vowel context. Overall, the sibilant fricatives seem particularly resistant to coarticulation and to variability in production, while the nonsibilant dental shows a good deal of variability, including some conditioning by the vowel context. These results have implications for the hyper- and hypo-theory of speech production. It is suggested that sibilant fricatives do not lend themselves to the articulatory imprecision, which characterizes other perceptually salient, and typologically common, speech sounds.
The wave bivector formalism associated with circumferential leaky waves
Authors: Padilla Frédéric , Poirée Bernard , Talmant Maryline , Quentin Gérard
Published: July 2002

It is shown that the circumferential internal waves propagating around an elastic cylinder can be locally seen as plane evanescent waves, at any observation point inside the surrounding fluid. This is done by direct calculation of the associated complex bivector. The exact anatomy of the wave is detailed and the phase propagation paths are found to be curved, as expected. The transition to the plane interface is achieved. Polarization ellipses associated with the acoustic displacement vector are described. The additional low evanescence assumption leads to conventional ray interpretation with identification of the ray tube divergence coefficients, and the wavefront is found to be the involute of a circle.
Pitch matches between unresolved complex tones differing by a single interpulse interval
Authors: Plack Christopher J. , White Louise J.
Published: July 2002

The experiment compared the pitches of complex tones consisting of unresolved harmonics. The fundamental frequency (F0) of the tones was 250 Hz and the harmonics were bandpass filtered between 5500 and 7500 Hz. Two 20-ms complex-tone bursts were presented, separated by a brief gap. The gap was an integer number of periods of the waveform: 0, 4, or 8 ms. The envelope phase of the second tone burst was shifted, such that the interpulse interval (IPI) across the gap was reduced or increased by 0.25 or 0.75 periods (1 or 3 ms). A “no shift” control was also included, where the IPI was held at an integer number of periods. Pitch matches were obtained by varying the F0 of a comparison tone with the same temporal parameters as the standard but without the shift. Relative to the no-shift control, the variations in IPI produced substantial pitch shifts when there was no gap between the bursts, but little effect was seen for gaps of 4 or 8 ms. However, for some conditions with the same IPI in the shifted interval, an increase in the IPI of the comparison interval from 4 to 8 ms (gap increased from 0 to 4 ms) changed the pitch match. The presence of a pitch shift suggests that the pitch mechanism is integrating information across the two tone bursts. It is argued that the results are consistent with a pitch mechanism employing a long integration time for continuous stimuli that is reset in response to temporal discontinuities. For a 250-Hz F0, an 8-ms IPI may be sufficient for resetting. Pitch models based on a spectral analysis of the simulated neural spike train, on an autocorrelation of the spike train, and on the mean rate of pitch pulses, all failed to account for the observed pitch matches.
Viscoelastic Behavior in Stagnation Flow
Authors: Leider P. J. , Lilleleht L. U.
Published: July 2002

The kinematics and the principal stress difference were determined for a 5% solution of polyisobutylene in mineral oil undergoing plane stagnation flow. These results were then used to evaluate four constitutive equations. The stagnation flow data were obtained for flow into a “T” shaped channel with measurements taken along the centerline. The kinematics consisted of the velocity distribution, and they confirmed the presence of a stagnant zone in which there was no downward flow. The velocity and position data, in a reduced form, were found to superimpose for several flow rates so that a master curve could be used with the constitutive equations to predict the stress differences. The latter were then compared with stress differences determined using a stress-birefringence apparatus constructed for this purpose. The experimental stress difference along the centerline went through a maximum when plotted against position. The following constitutive equations were evaluated: the White-Metzner, the Oldroyd 3-constant, the BKZ, and the WJFLMB equations. The rheological parameters in these equations were obtained using stress-birefringence data for steady shear flow through a rectangular channel. Each of the equations correctly predicted a delayed normal stress difference growth as a function of time. The WJFLMB model was found unsatisfactory in its ability to predict the magnitude of the stress difference. All the remaining models did a reasonably good job in their predictions with the Oldroyd model being slightly superior at high deformation rates.
Large Elastic Deformation Theories and Unstable Deformations of Rubber Structures: Thick Tubes
Authors: Charrier J.-M. , Li Y. K.
Published: July 2002

A variety of quantitative theories for the large elastic deformations of rubbers have been proposed. Most useful for applications in engineering, for example, because they most readily lead to the presentation of computed results in dimensionless form, are those which involve one elastic constant only (such as Young's modulus) in addition to Poisson's ratio (0.5 for incompressible rubbers). Two such theories (referred to as the Neo-Hookean and the Varga, Dickie-Smith elasticities) are considered here and applied to the analysis of large deformations of thick cylindrical rubber tubes. Predictions are compared to experimental results. The deformations considered are basically divided into two types: 1) longitudinal extension under constant inside pressure in which the tube is longitudinally extended by applying a variable longitudinal force while a constant pressure is maintained inside; 2) inflation under constant longitudinal force in which the tube is inflated by applying a variable pressure while a constant longitudinal force is exerted. Simple extension is a special case of type 1 when the constant pressure is zero and simple inflation is a special case of type 2 when the constant longitudinal force is zero.
Negative electrorheological effect and electrical properties of a Teflon/silicone oil suspension
Authors: Wu C. W. , Conrad H.
Published: July 2002

A suspension (φ=0.2) of Teflon particles in silicone oil exhibited a negative electrorheological response with a dc electric field. This was in keeping with the fact that the conductivity of the host liquid σf was considerably greater than that of the particles σp, giving for the complex dielectric mismatch parameter β*=−1/2. Microscopy observations revealed that with application of a dc electric field the Teflon particles migrated to the positive electrode resulting in a structure which consisted of two layers or zones: (a) a relatively pure liquid and (b) a more concentrated suspension. The thickness of the liquid zone increased with field strength, which led to the decrease in the shear stress with field. A numerical analysis was developed for the electrical properties of the segregated suspension, which gave good agreement with measured values.
A synchrotron X-ray diffraction study of a small congruent LiNbO3crystal: A compatible approach to powder diffraction
Authors: Etschmann Barbara , Ishizawa Nobuo
Published: July 2002

Single-crystal synchrotron X-ray diffraction (XRD) data were collected and refined for congruent lithium niobate crystals 8 and 6 μm in diameter, sizes that are comparable to the size of the powder particles used in powder diffraction. The motivation for using such small crystals is to minimize problems such as extinction, which decrease with crystal size. The R/wR factors were 0.011/0.014 and 0.019/0.018, for the 8 and 6 μm data, respectively, and the goodness of fit factors were 2.3(1) and 1.63(8), which compare favorably with values obtained from previous powder and single-crystal diffraction studies. Results from single-crystal XRD using crystals less than 10 μm in size may rival those obtained from powder diffraction.
Treating Opioid Use Disorder in Patients Who Are Incarcerated
Authors: South Anna-Maria , Fanucchi Laura , Lofwall Michelle
Published: April 2023

This Viewpoint discusses the importance of ensuring that life-saving medication for opioid use disorder is available to hospitalized persons who are incarcerated.
Analysis of Obstetric Outcomes by Hospital Location, Volume, and Teaching Status Associated With Non–Medically Indicated Induction of Labor at 39 Weeks
Authors: Hersh Alyssa R. , Bullard Kimberley A. , Garg Bharti , Arora Megha , Mischkot Brooke F. , Caughey Aaron B.
Published: April 2023

Importance

Non–medically indicated induction of labor has been demonstrated to potentially improve some obstetric outcomes, such as decreasing cesarean birth. It has been reported that rates of cesarean birth and other obstetric outcomes vary among hospitals with different characteristics.

Objective

To assess whether obstetric outcomes differ between nulliparous individuals with low-risk pregnancies managed with non–medically indicated induction of labor compared with expectant management in different types of hospitals.

Design, Setting, and Participants

This retrospective cohort study included non–medically indicated induction of labor at 39 weeks' gestation compared with expectant management of singleton, nonanomalous, births in nulliparous women with low-risk pregnancies in California between January 1, 2007, and December 31, 2011. The initial analysis of these data was performed in 2021. Outcomes were assessed by 3 hospital characteristics: location (urban vs rural), obstetric volume, and teaching (academic vs community) status. Volume was categorized based on the average number of births per year and grouped into low (<1200 births per year), medium (1200-2399 births per year), and high (≥2400 births per year). Births with previous or planned cesarean delivery were excluded, and non–medically indicated induction of labor was defined as induction of labor without a specific medical indication. Testing with χ2 and multivariable logistic regression analyses was used for statistical comparisons with a cutoff level of P = .01.

Exposure

Non–medically indicated induction of labor at 39 weeks’ gestation.

Main Outcomes and Measures

The primary outcome was cesarean birth, and numerous secondary perinatal outcomes were also assessed.

Results

There were 455 044 births included in this study. When stratified by hospital variables, a number of sociodemographic characteristics were significantly different, such as race and ethnicity, age, body mass index, and insurance type. The adjusted odds ratios (aORs) of cesarean birth were significantly lower in all settings with induction of labor except for low-volume hospitals, in which there was no significant difference (aOR, 0.95; 95% CI, 0.82-1.09). Chorioamnionitis and postpartum hemorrhage were lower with induction of labor among nearly every hospital when stratified by hospital characteristics. Neonatal outcomes were improved in all settings with induction of labor compared with expectant management.

Conclusions and Relevance

These findings suggest that non–medically indicated induction of labor may be associated with a lower rate of cesarean births and some maternal and neonatal adverse outcomes in a range of hospital settings.
Estimating mesocarnivore abundance on commercial farmland using distance sampling with camera traps
Authors: McKaughan Jamie E. T. , Stephens Philip A. , Hill Russell A.
Published: April 2023

Mesocarnivores are of particular interest in wildlife management. Their adaptability makes them a focus of public attention globally, as negative interactions with people occur regularly, but their importance to wider ecosystem function is increasingly apparent. Robust methods for estimating mesocarnivore densities are essential for long‐term management strategies. Estimating densities of unmarked populations remains challenging, but new methods, based on camera trapping, have recently become available and require field testing.

We conducted two camera trap surveys over two 200 km2areas of commercial farmland in South Africa. One survey sampled 25 locations, while the second used a migrating grid to sample 59 locations; total sampling effort was similar across the two surveys. We applied distance sampling with camera traps (CTDS), developing a method to estimate animal distances by applying a distance measurement overlay grid to camera trap images.

We aimed to establish meaningful density estimates of the mesocarnivore guild and evaluate CTDS's suitability for broader use with these types of species. We obtained density estimates for four carnivores, African civetCivettictis civetta, black‐backed jackalCanis mesomelas, brown hyenaHyaena brunneaand caracalCaracal caracal, providing valuable insight into their status in commercial farmland. Imprecision in the estimates was almost exclusively due to encounter rate variance, which was not reduced with the migrating camera grid.

We explored the sensitivity of our results to assumptions determining the value of the ‘snapshot interval’, demonstrating that careful selection of this parameter is vital to ensuring reliable estimates when using rapid‐fire photo burst modes.

CTDS can provide useful density estimates for mesocarnivores, but future studies should aim to maximize precision and reliability by increasing sampling locations. More studies are required in areas with known densities to promote confidence in accuracy.
Improving synthetic CT accuracy by combining the benefits of multiple normalized preprocesses
Authors: Cao Zheng , Gao Xiang , Chang Yankui , Liu Gongfa , Pei Yuanji
Published: April 2023

Purpose

To investigate the effect of different normalization preprocesses in deep learning on the accuracy of different tissues in synthetic computed tomography (sCT) and to combine their advantages to improve the accuracy of all tissues.

Methods

The cycle‐consistent adversarial network (CycleGAN) model was used to generate sCT images from megavolt cone‐beam CT (MVCBCT) images. In this study, 2639 head MVCBCT and CT image pairs from 203 patients were collected as a training set, and 249 image pairs from 29 patients were collected as a test set. We normalized the voxel values in images to 0 to 1 or −1 to 1, using two linear and five nonlinear normalization preprocessing methods to obtain seven data sets and compared the accuracy of different tissues in different sCT obtained from training these data. Finally, to combine the advantages of different normalization preprocessing methods, we obtained sCT_Blur by cropping, stitching, and smoothing (OpenCV's cv2.medianBlur, kernel size 5) each group of sCTs and evaluated its image quality and accuracy of OARs.

Results

Different normalization preprocesses made sCT more accurate in different tissues. The proposed sCT_Blur took advantage of multiple normalization preprocessing methods, and all tissues are more accurate than the sCT obtained using a single conventional normalization method. Compared with other sCT images, the structural similarity of sCT_Blur versus CT was improved to 0.906 ± 0.019. The mean absolute errors of the CT numbers were reduced to 15.7 ± 4.1 HU, 23.2 ± 7.1 HU, 11.5 ± 4.1 HU, 212.8 ± 104.6 HU, 219.4 ± 35.1 HU, and 268.8 ± 88.8 HU for the oral cavity, parotid, spinal cord, cavity, mandible, and teeth, respectively.

Conclusion

The proposed approach combined the advantages of several normalization preprocessing methods to improve the accuracy of all tissues in sCT images, which is promising for improving the accuracy of dose calculations based on CBCT images in adaptive radiotherapy.
Tumor Microenvironment‐Responsive Nanocarrier Based on VOx Nanozyme Amplify Oxidative Stress for Tumor Therapy
Authors: Zhang Fang , Cheng Kai , Huang Zhuo‐Yao , Hou Xiao‐Lin , Zhang Xiao‐Shuai , Zhong Zi‐Tao , Hu Yong‐Guo , Lei Xiao‐Ling , Li Yong , Zhang Pei‐Jie , Zhao Yuan‐Di , Xu Qiu‐Ran
Published: April 2023

The construction of a novel nanocarrier that can break the redox balance in tumor cell is a promising anti‐tumor strategy. Herein, a tumor microenvironment (TME)‐responsive nanocarrier VC@Lipo is rationally designed by embedding ultrasmall VOx nanozyme and photosensitizer chlorin e6 (Ce6) into liposomes. The size of VC@Lipo nanocarrier is ≈35 nm and can be degraded in the weakly acidic environment of TME. The VOx nanozyme exhibits peroxidase‐like activity and generates highly toxic hydroxyl radical ∙OH through Fenton‐like reaction and 1O2 in the presence of H2O2 independent of light, and more 1O2 can be generated by the photodynamic effect of Ce6. In addition, the VOx nanozyme can effectively deplete intracellular overexpressed glutathione (GSH) through redox reactions. In vivo experiments demonstrate that the nanocarrier shows excellent biocompatibility, presents the largest enrichment at the tumor site after 6 h of intravenous injection into mice with the highest tumor inhibition rate of 54.18% after laser irradiation. Compared with the single treatment mode, VC@Lipo shows the best synergistic effect of chemodynamic‐photodynamic therapy. This work provides a new paradigm for nanocatalytic therapy of cancer and is expected to provide new ideas for precision medicine in cancer.
Dual Catalytic Sites of Alloying Effect Bloom CO2 Catalytic Conversion for Highly Stable Li–CO2 Battery
Authors: Wang Zhen , Liu Bao , Yang Xing , Zhao Changtai , Dong Peng , Li Xue , Zhang Yannan , Doyle‐Davis Kieran , Zeng Xiaoyuan , Zhang Yingjie , Sun Xueliang
Published: April 2023

Owing to the ingenious utilization of CO2 conversion electrochemistry, rechargeable Li–CO2 batteries, have attracted more and more attention. However, the large potential polarization resulting from the sluggish CO2 reduction/evolution electrochemistry degrades energy efficiency and cycling performance. One possibility to break the kinetic bottlenecks of ‐Li–CO2 batteries is to design high‐efficiency catalysts with flexible geometric and electronic structures. Herein, an efficient synergistic catalyst with unique alloyed dual catalytic sites composed of uniformly ultrafine Ir–Ru alloyed nanoparticles modified nitrogen‐doped carbon nanotube composite (denoted as IrRu/N‐CNT) is synthesized. Combining the synergistic effect between the remarkably enhanced catalytic activity of Ir–Ru dual catalytic sites, the Li–CO2 battery delivers a high discharge capacity of 6228 mAh g−1 and outstanding stability over 7660 h. Density functional theory (DFT) calculation results uncover that the excellent electrochemical performance is ascribed to the novel dual catalytic sites on the surface of IrRu nanoalloys, which effectively modify its electronic structures and shorten the electron transfer pathway, leading to the deposition of film‐like Li2CO3 products. This study highlights the novel view of building a dual catalytic site and provides some new insights for understanding the catalytic mechanism of an alloying‐type bifunctional catalyst toward realizing high‐performance Li–CO2 batteries.
Does Salt Concentration Matter? New Insights on the Intercalation Behavior of PF6−${\rm{PF}}_6^ - $ into Graphite Cathode for the Dual‐Ion Battery
Authors: Guan Dichang , Wang Weigang , Chen Bo , Wu Jiahui , Hu Guorong , Peng Zhongdong , Cao Yanbing , Wen Lei , Du Ke
Published: April 2023

A high‐concentration electrolyte is favored in dual‐ion batteries (DIBs) due to the lower onset potential for anion intercalation, higher specific discharge capacity, and better oxidation stability. Inspired by the correlation between the high‐concentration electrolytes and localized high‐concentration electrolytes, it is suspected that it is not the salt concentration but the solution structure of the electrolyte that determines the intercalation behavior of anion into graphite cathode. To prove the viewpoint, a series of electrolytes are prepared by controlling the salt concentration or solution structure and the intercalation behavior of within the graphite cathode is investigated in Li||graphite and graphite||graphite cells. It is found that anions exhibit similar onset potentials and specific discharge capacities in the electrolytes with different salt concentrations but similar solution structures. This study provides a new perspective on designing promising electrolytes for DIBs, which can accelerate the further exploitation of high‐performance DIBs.
Glycopeptide‐Based Multifunctional Hydrogels Promote Diabetic Wound Healing through pH Regulation of Microenvironment
Authors: Xia Hao , Dong Ze , Tang Qi , Ding Rongjian , Bai Yimeng , Zhou Ke , Wu Lihuang , Hao Lili , He Yiyan , Yang Jun , Mao Hongli , Gu Zhongwei
Published: April 2023

Excessive inflammation, bacterial infection, and blocked angiogenesis make diabetic wound healing challenging. Multifunctional wound dressings have several advantages in diabetic wound healing. In addition, the pH regulation of the microenvironment is shown to be a key factor that promotes skin regeneration through cellular immune regulation. However, few reports have focused on the development of functional dressings with the ability to regulate the pH microenvironment and promote diabetic wound healing. This study presents a novel approach for regulating the pH microenvironment of diabetic wound sites using a glycopeptide‐based hydrogel consisting of modified hyaluronic acid and poly(6‐aminocaproic acid). This hydrogel forms a network through Schiff base interactions and metal complexation, which suppresses inflammation and accelerates angiogenesis during wound healing. Hydrogels not only have adequate mechanical properties and self‐healing ability but can also support tissue adhesion. They can also promote the secretion of inducible cAMP early repressor, which promotes the polarization of macrophages toward the M2 type. The in vivo results confirm that hydrogel promotes diabetic wound repair and skin regeneration by exerting rapid anti‐inflammatory effects and promoting angiogenesis. Therefore, this hydrogel system represents an effective strategy for treating diabetic wounds.
Suppressing Ion Migration of Mixed‐Halide Perovskite Quantum Dots for High Efficiency Pure‐Red Light‐Emitting Diodes
Authors: Xie Mingyuan , Guo Jie , Zhang Xiaoyu , Bi Chenghao , Sun Xuejiao , Li Hangren , Zhang Lin , Binks David , Li Gang , Zheng Weitao , Tian Jianjun
Published: April 2023

Perovskite‐based light‐emitting diodes (PeLEDs) with a mixed halide composition can be used to obtain the “pure red” emission, i.e., in the 620–650 nm range, required for high‐definition displays. However, fast halide ion migration induces phase separation in these materials under electric fields, resulting in poor spectral stability and low efficiency. Herein, a method for producing mixed halide CsPbI3‐xBrx quantum dots (QDs) is reported in which ion migration is suppressed. The mixed halide composition is first achieved by anion exchange between CsPbI3 QDs and hydrobromic acid (HBr), during that the bromine ions efficiently passivate the iodine vacancies of the QDs. The original oleic acid ligands are then exchanged for 1‐dodecanethiol (1‐DT), which suppresses halide ion migration via the strong binding of the sulfhydryl group with the QD surface. PeLEDs based on these QDs exhibit a pure‐red electroluminescence (EL) peak at 637 nm, a maximum external quantum efficiency (EQE) of 21.8% with an average value of 20.4%, a peak luminance of 2653 cd m−2, and low EQE decease with increasing luminance. The EL spectrum of these devices is stable even at 6.7 V and they have an EQE half‐life of 70 min at an initial luminance of 150 cd m−2.
Evoking Cooperative Geometric and Electronic Interactions at Nanometer Coherent Interfaces toward Enhanced Electrocatalysis
Authors: Song Huijun , Xu Xiaoqiu , Chen Jingjing , Zhang Yinling , Zhao Jia , Zhu Chongzhi , Zhang Hong , Peng Yong , Chen Qiaoli , Sheng Guan , Sun Tulai , Han Yu , Li Xiaonian , Zhu Yihan
Published: April 2023

Integrating high‐valence metal sites into transition metal‐based oxygen evolution reaction (OER) catalysts turns out to be a prevailing solution to replacing noble metal‐based electrocatalysts. However, stabilizing the thermodynamically unfavorable high‐valence metal sites within the electrocatalyst remains challenging. Hereby, a general strategy is proposed that evokes cooperative geometric and electronic interactions at nanometer coherent interfaces, which effectively stabilizes interfacial high‐valence metal sites within homogeneously distributed heterostructures and significantly enhances electrocatalytic activity. As a proof‐of‐concept study, by derivatizing multicomponent isoreticular hybridized metal–organic frameworks with separated σ‐ or π‐bonded moieties, bimetal Ni–Fe selenides heterostructures with nanoscopic compositional and structural homogeneity are grafted. Such heterostructures entail nanometer‐sized coherent interfaces that accommodate large geometric distortions and cooperatively stabilize the energetically unfavorable Jahn–Teller active electronic states of high‐valence interfacial Ni sites. The presence of high‐valence interfacial Ni sites and associated collective Jahn–Teller distortions greatly facilitate the Ni oxidation cycling through Ni3+/Ni4+ transition and stabilizes the *O key intermediate at Ni‐Se dual sites, both of which synergistically lowers down the overall OER overpotential.