bluuebunny/crossref_metadata_2025 huggingface dataset:
Endocannabinoids control spasticity in a multiple sclerosis model
Authors: Baker David , Pryce Gareth , Croxford J. Ludovic , Brown Peter , Pertwee Roger G. , Makriyannis Alexandros , Khanolkar Atmaram , Layward Lorna , Fezza Filomena , Bisogno Tiziana , Marzo Vincenzo Di
Published: July 2002

Spasticity is a complicating sign in multiple sclerosis that also develops in a model of chronic relapsing experimental autoimmune encephalomyelitis (CREAE) in mice. In areas associated with nerve damage, increased levels of the endocannabinoids, anandamide (arachidonoylethanolamide, AEA) and 2‐arachidonoyl glycerol (2‐AG), and of the AEA congener, palmitoylethanolamide (PEA), were detected here, whereas comparable levels of these compounds were found in normal and non‐spastic CREAE mice. While exogenously administered endocannabinoids and PEA ameliorate spasticity, selective inhibitors of endocannabinoid re‐uptake and hydrolysis—probably through the enhancement of endogenous levels of AEA, and, possibly, 2‐arachidonoyl glycerol—significantly ameliorated spasticity to an extent comparable with that observed previously with potent cannabinoid receptor agonists. These studies provide definitive evidence for the tonic control of spasticity by the endocannabinoid system and open new horizons to therapy of multiple sclerosis, and other neuromuscular diseases, based on agents modulating endocannabinoid levels and action, which exhibit little psychotropic activity.
The evolutionary genetics of speciation
Authors: Coyne Jerry A. , Allen Orr H.
Published: July 2002

The last decade has brought renewed interest in the genetics of speciation, yielding a number of new models and empirical results. Defining speciation as ‘the origin of reproductive isolation between two taxa’, we review recent theoretical studies and relevant data, emphasizing the regular patterns seen among genetic analyses. Finally, we point out some important and tractable questions about speciation that have been neglected.
Interactions between tobacco mosaic virus and the tobacco
N
gene
Authors: Erickson F. L. , Dinesh-Kumar S. P. , Holzberg S. , Ustach C. V. , Dutton M. , Handley V. , Corr C. , Baker B. J.
Published: July 2002

The interaction between tobacco mosaic virus (TMV) and tobacco harbouring the
N
gene is a classical system for studying gene–for–gene interactions in disease resistance. The
N
gene confers resistance to TMV by mediating defence responses that function to limit viral replication and movement. We isolated the
N
gene and determined that
N
belongs to the nucleotide–binding–site–leucine–rich–repeat (NBS–LRR) class of plant disease resistance genes, and encodes both full–length and truncated proteins. Sequence homologies and mutagenesis studies indicated a signalling role for the N protein similar to that seen for proteins involved in defence responses in insects and mammals. The
N
gene confers resistance to TMV in transgenic tomato, demonstrating the use of the NBS–LRR class of disease resistance genes in engineering crop resistance. From the pathogen side of this interaction, the TMV 126 kDa replicase protein has been implicated as the avirulence factor that triggers
N
–mediated defence responses. We employed
Agrobacterium
–mediated expression strategies to demonstrate that expression of the putative helicase region of the replicase protein is sufficient to elicit
N
–mediated defences. The thermosensitivity of the
N
–mediated response to TMV is retained when induced by expression of this replicase fragment. Thus, both components of this gene–for–gene interaction are now available for studies that address the molecular mechanisms involved in
N
–mediated TMV resistance.
The ecoclimatology of Danum, Sabah, in the context of the world's rainforest regions, with particular reference to dry periods and their impact
Authors: Walsh R. P. D. , Newbery D. M.
Published: July 2002

Climatic records for Danum for 1985 to 1998, elsewhere in Sabah since 1879, and long monthly rainfall series from other rainforest locations are used to place the climate, and particularly the dry period climatology, of Danum into a world rainforest context. The magnitude frequency and seasonality of dry periods are shown to vary greatly within the world's rainforest zone. The climate of Danum, which is aseasonal but subject, as in 1997 to 1998, to occasional drought, is intermediate between less drought–prone north–western Borneo and the more drought–prone east coast. Changes through time in drought magnitude frequency in Sabah and rainforest locations elsewhere in South–East Asia and in the Neotropics are compared. The 1997 to 1998 ENSO–related drought event in Sabah is placed into a historical context. The effects of drought on tree growth and mortality in the tropics are assessed and a model relating intensity and frequency of drought disturbance to forest structure and composition is discussed.
Quorum sensing and the population-dependent control of virulence
Authors: Williams Paul , Camara Miguel , Hardman Andrea , Swift Simon , Milton Deborah , Hope Victoria J. , Winzer Klaus , Middleton Barrie , Pritchard David I. , Bycroft Barrie W.
Published: July 2002

One crucial feature of almost all bacterial infections is the need for the invading pathogen to reach a critical cell population density sufficient to overcome host defences and establish the infection. Controlling the expression of virulence determinants in concert with cell population density may therefore confer a significant survival advantage on the pathogen such that the host is overwhelmed before a defence response can be fully initiated. Many different bacterial pathogens are now known to regulate diverse physiological processes including virulence in a cell–density–dependent manner through cell–cell communication. This phenomenon, which relies on the interaction of a diffusible signal molecule (e.g. an N –acylhomoserine lactone) with a sensor or transcriptional activator to couple gene expression with cell population density, has become known as ‘quorum sensing’ . Although the size of the ‘quorum’ is likely to be highly variable and influenced by the diffusibility of the signal molecule within infected tissues, nevertheless quorum–sensing signal molecules can be detected in vivo in both experimental animal model and human infections. Furthermore, certain quorum–sensing molecules have been shown to possess pharmacological and immunomodulatory activity such that they may function as virulence determinants
per se
. As a consequence, quorum sensing constitutes a novel therapeutic target for the design of small molecular antagonists capable of attenuating virulence through the blockade of bacterial cell–cell communication.
On the lens pad ofBenthalbella infans, a scopelarchid deep–sea teleost
Authors: Locket N. A.
Published: July 2002

The tubular eye of scopelarchids contains a lens pad, derived from cornea, lateral to the lens and opposite a gap in the iris. The pad, transparent in life, is formed of optically dense lamellae arranged atca.45° to the sagittal plane of the fish. The lamellae areca.155 nm thick, separated byca.185 nm. The pad does not deviate light passing normally through the lamellae, but does deviate light at an acute angle to the lamellae unequally throughca.40°, converting a spot to a streak. Light fromca.20° to the vertical below the fish will be projected onto the accessory retina of the dorsally pointing tubular eyes. The pad also disperses white light, blue lightca.34° and red lightca.44°. The deviation of light from below may enable the fish to detect predators below, and the dispersion may play a role in breaking camouflage by spreading photophore light over an area of retina.
The structural basis of protein folding and its links with human disease
Authors: Dobson Christopher M.
Published: July 2002

The ability of proteins to fold to their functional states following synthesis in the intracellular environment is one of the most remarkable features of biology. Substantial progress has recently been made towards understanding the fundamental nature of the mechanism of the folding process. This understanding has been achieved through the development and concerted application of a variety of novel experimental and theoretical approaches to this complex problem. The emerging view of folding is that it is a stochastic process, but one biased by the fact that native–like interactions between residues are on average more stable than non–native ones. The sequences of natural proteins have emerged through evolutionary processes such that their unique native states can be found very efficiently even in the complex environment inside a living cell. But under some conditions proteins fail to fold correctly, or to remain correctly folded, in living systems, and this failure can result in a wide range of diseases. One group of diseases, known as amyloidoses, which includes Alzheimer's and the transmissible spongiform encephalopathies, involves deposition of aggregated proteins in a variety of tissues. These diseases are particularly intriguing because evidence is accumulating that the formation of the highly organized amyloid aggregates is a generic property of polypeptides, and not simply a feature of the few proteins associated with recognized pathological conditions. That such aggregates are not normally found in properly functional biological systems is again a testament to evolution, in this case of a variety of mechanisms inhibiting their formation. Understanding the nature of such protective mechanisms is a crucial step in the development of strategies to prevent and treat these debilitating diseases.
Computational analysis of binding of P1 variants to trypsin
Authors: Brandsdal Bjørn O. , Åqvist Johan , Smalås Arne O.
Published: July 2002

The binding of P1 variants of bovine pancreatic trypsin inhibitor (BPTI) to trypsin has been investigated by means of molecular dynamics simulations. The specific interaction formed between the amino acid at the primary binding (P1) position of the binding loop of BPTI and the specificity pocket of trypsin was estimated by use of the linear interaction energy (LIE) method. Calculations for 13 of the naturally occurring amino acids at the P1 position were carried out, and the results obtained were found to correlate well with the experimental binding free energies. The LIE calculations rank the majority of the 13 variants correctly according to the experimental association energies and the mean error between calculated and experimental binding free energies is only 0.38 kcal/mole, excluding the Glu and Asp variants, which are associated with some uncertainties regarding protonation and the possible presence of counter‐ions. The three‐dimensional structures of the complex with three of the P1 variants (Asn, Tyr, and Ser) included in this study have not at present been solved by any experimental techniques and, therefore, were modeled on the basis of experimental data from P1 variants of similar size. Average structures were calculated from the MD simulations, from which specific interactions explaining the broad variation in association energies were identified. The present study also shows that explicit treatment of the complex water‐mediated hydrogen bonding network at the protein–protein interface is of crucial importance for obtaining reliable binding free energies. The successful reproduction of relative binding energies shows that this type of methodology can be very useful as an aid in rational design and redesign of biologically active macromolecules.
The Penrose dodecahedron revisited
Authors: Massad Jordan E. , Aravind P. K.
Published: July 2002

This paper gives an elementary account of the “Penrose dodecahedron,” a set of 40 states of a spin-32 particle used by Zimba and Penrose [Stud. Hist. Phil. Sci. 24, 697–720 (1993)] to give a proof of Bell’s nonlocality theorem. The Penrose rays are constructed here from the rotation operator of a spin-32 particle and the geometry of a dodecahedron, and their orthogonality properties are derived and illustrated from a couple of different viewpoints. After recalling how the proof of Bell’s theorem can be reduced to a coloring problem on the Penrose rays, a “proof-tree” argument is used to establish the noncolorability of the Penrose rays and hence prove Bell’s theorem.
Basilar membrane responses to broadband stimuli
Authors: Recio Alberto , Rhode William S.
Published: July 2002

Basilar membrane (BM) responses to two types of broadband stimuli—clicks and Schroeder-phase complexes—were recorded at several sites at the base of the chinchilla cochlea. Recording sites (characteristic frequency, CF, in the range of 5.5–18 kHz) span the 1–4-mm basal region of the basilar membrane. BM responses to clicks consisted of undamped oscillations with instantaneous frequency that increased over time until it reached a value around CF. The time constant of this glide is CF dependent. Throughout the entire region under study, BM vibration exceeded umbo motion by up to 60 dB. Nonlinear properties of BM responses to clicks resemble those found in the more studied 8–10-kHz region. Amplitude spectra of Schroeder-phase complex stimuli, which consist of a series of sinusoidal components summed in negative (−SCHR) and positive Schroeder phase (+SCHR), are flat. The envelope of BM responses to +SCHR stimuli contains valleys, or dips, that are wider than those found in responses to the −SCHR stimuli. Hence, BM responses to the former stimuli are “peakier” than responses to the latter. Differences in response waveforms are less obvious in linear cochleae. Suppression of a near-CF tone by −SCHR stimuli was larger than that evoked by +SCHR stimuli.
An evaluation of the accuracy of shallow water matched field inversion results
Authors: Snellen Mirjam , Simons Dick G. , Siderius Martin , Sellschopp Jürgen , Nielsen Peter L.
Published: July 2002

In this article the accuracy of geo-acoustic and geometric parameter estimates obtained through matched field inversion (MFI) was assessed. Multi-frequency MFI was applied to multi-tone data (200–600 Hz) received at a 2-km source/receiver range. The acoustic source was fixed and the signals were received at a vertical array. Simultaneously with the acoustic transmissions, a CTD (conductivity, temperature and depth)-chain was towed along the acoustic track. A genetic algorithm was used for the global optimization, whereas a normal mode model was applied for the forward acoustic calculations. Acoustic data received at consecutive times were inverted and the stability of the inverted parameters was determined. Also, the parameter estimates were compared with independent measurements, such as multi-channel seismic surveys (for geo-acoustic parameters). The obtained uncertainty in the inversion results was assumed to have two distinct origins. The first origin is the inversion method itself, since each optimization will come up with some solution close to the exact optimum. Parameter coupling and the fact that some parameters hardly influence the acoustic propagation further contribute to this uncertainty. The second is due to oceanographic variability. Both contributions were evaluated through simulation. The contribution of oceanographic variability was evaluated through synthetic inversions that account for the actual sound speed variations as measured by the towed CTD-chain.
Community noise exposure and stress in children
Authors: Evans Gary W. , Lercher Peter , Meis Markus , Ising Hartmut , Kofler Walter W.
Published: July 2002

Although accumulating evidence over the past two decades points towards noise as an ambient stressor for children, all of the data emanate from studies in high-intensity, noise impact zones around airports or major roads. Extremely little is known about the nonauditory consequences of typical, day-to-day noise exposure among young children. The present study examined multimethodological indices of stress among children living under 50 dB or above 60 dB (A-weighted, day-night average sound levels) in small towns and villages in Austria. The major noise sources were local road and rail traffic. The two samples were comparable in parental education, housing characteristics, family size, marital status, and body mass index, and index of body fat. All of the children were prescreened for normal hearing acuity. Children in the noisier areas had elevated resting systolic blood pressure and 8-h, overnight urinary cortisol. The children from noisier neighborhoods also evidenced elevated heart rate reactivity to a discrete stressor (reading test) in the laboratory and rated themselves higher in perceived stress symptoms on a standardized index. Furthermore girls, but not boys, evidenced diminished motivation in a standardized behavioral protocol. All data except for the overnight urinary neuroendocrine indices were collected in the laboratory. The results are discussed in the context of prior airport noise and nonauditory health studies. More behavioral and health research is needed on children with typical, day-to-day noise exposure.
Wave reflections from duct terminations
Authors: Selamet A. , Ji Z. L. , Kach R. A.
Published: July 2002

The reflection coefficients and inertial end corrections of several duct terminations, including finite length duct extensions perpendicular to an infinite wall, as well as at a number of angles, curved interface surfaces, and annular cavities, are determined and analyzed in the absence of flow by employing the boundary element method. Predictions for the classical unflanged and flanged circular ducts show good agreement with analytical and computational results available in the literature. The predictions for curved interface surfaces (bellmouth or horn) are also consistent with the available experimental data. In view of its high reflection coefficient, the duct termination with an annular cavity may be suggested for the suppression of noise radiation in a specific frequency band or for an effective wave reflection from the termination.
Measurement of electrostrictive coefficients of polymer films
Authors: Guillot François M. , Jarzynski Jacek , Balizer Edward
Published: July 2002

A new technique to experimentally determine the electrostrictive coefficients of thin polymer films is presented. This technique is a second-order extension of the first-order quasistatic method for the measurement of piezoelectric coefficients previously introduced by Guillot and Jarzynski [J. Acoust. Soc. Am. 108, 600–607 (2000)]. In the present method, electrically induced strains are measured optically on a rubber-encapsulated sample. These strains are used in a Rayleigh–Ritz procedure that minimizes the total energy of the sample and whose output is a set of three tensile electrostrictive coefficients. The total energy of the sample includes elastic contributions from the polymer and the encapsulating rubber as well as two quadratic electromechanical terms corresponding to Maxwell stress and to electrostriction. Therefore, the external electrostatic effects can be separated from the intrinsic electrostrictive behavior, and the measured coefficients are true material properties. Data obtained on two types of polyurethanes submitted to a bias field of approximately 4 MV/m at 2 kHz and at room temperature are presented. It was found that these materials possess very large electrostrictive coefficients and that the Maxwell stress effect is responsible for less than 13% of their total electromechanical behavior.
Statistical properties of estimates of signal-to-noise ratio and number of scatterers per resolution cell
Authors: Wear Keith A. , Wagner Robert F. , Brown David G. , Insana Michael F.
Published: July 2002

Elementary theory underlying the relationship between the number of scatterers per resolution cell (N) and echo intensity signal-to-noise ratio (SNR) is reviewed. A relationship between the probability density functions for estimates of N and SNR2 is derived. This relationship is validated using a computer simulation. Phantom and in vitro experiments are described. In one set of experiments on phantoms, empirical distributions of estimates of N and SNR2 are measured and compared to theoretical predictions. The utility of SNR2 for discrimination of phantoms with different values for N is assessed using receiver operating characteristic (ROC) analysis. In another set of experiments, the frequency dependence of the SNR2 estimate is investigated for a two-component phantom and for excised dog kidney. It is shown that the frequency dependence of the SNR can help to identify the presence of two or more scattering components that are spatially mixed. With regard to kidney data, measurements performed both parallel and perpendicular to the predominant nephron orientation are reported. The observed anisotropy is compared to the anisotropy of backscatter coefficient encountered in previous investigations.
Two separate codes for missing-fundamental pitch in the human auditory cortex
Authors: Winkler I. , Tervaniemi M. , Näätänen R.
Published: July 2002

Two auditory event-related potential components, the supratemporal N1 and the mismatch negativity (MMN), index traces encoding the missing-fundamental pitch. The present results suggest that these two codes derive from separate pitch extraction processes. Frequent 300-Hz and infrequent 600-Hz missing-fundamental tones were presented, in some stimulus blocks with short (150 ms), in others, with long (500 ms) stimulus durations. MMN, reflecting a preattentive change detection process, was elicited by infrequent missing-fundamental tones only in the long-duration condition. Correspondingly, subjects were able to detect these high-pitch missing-fundamental tones amongst similar low-pitch ones only when the stimulus duration was long. In addition, the MMN response peaked ca. 120 ms later for missing-fundamental tones than for pure tones of the fundamental frequency suggesting that missing-fundamental pitch resolving took substantially longer than extracting the spectral pitch. In contrast, a differential N1 response to the missing-fundamental pitch was found for both stimulus durations, with no substantial difference in peak latency between the pure and missing-fundamental tones. The contrasting features found for the two auditory cortical missing-fundamental pitch codes support the notion of two separate missing-fundamental pitch resolving mechanisms.
Eigenfunction analysis of radially polarized piezoelectric cylindrical shells of finite length
Authors: Ebenezer D. D. , Abraham Pushpa
Published: July 2002

An eigenfunction approach is presented to determine the response of radially polarized piezoelectric cylindrical shells of finite length to electrical excitation. The equations of motion of the piezoelectric cylinder are first derived by using the membrane approximation. Then they are solved by expressing the displacement distribution as the sum of the static solution and a weighted sum of a complete set of functions—the eigenfunctions of the short-circuited cylinder. The static solution is necessary to exactly satisfy the boundary conditions of the electrically excited cylinder. Moreover, in some cases, the series solution does not converge to the correct displacement distribution when some other terms, instead of the static solution, are used to satisfy the boundary conditions. The weights or displacement coefficients are determined by using the orthogonal property of the eigenfunctions. Finally, the input electrical admittance is determined by using the equation of state and the displacement distribution. Analyses of cylinders with various boundary conditions are presented to illustrate the approach. Numerical results are used to show that the series solutions converge very rapidly to the closed form solutions.
Acoustic and articulatory correlates of stop consonants in a parrot and a human subject
Authors: Patterson D. K. , Pepperberg I. M.
Published: July 2002

General acoustic patterns in productions of American English stops /p,b,t,d,k,g/ by a Grey parrot (Psittacus erithacus) and his primary human trainer are identified. Comparisons demonstrated both differences (coherence of voicing [/p,t,k/ and /b,d,g/] and place [/p,b/, /t,d/, and /k,g/] subsets, predictive power of measures related to F1 and F3) and similarities (categorical distinctions among stop consonants) in acoustic properties of psittacine and human speech. The authors suggest how acoustic data might be correlated with articulatory events in the parrot. Our data are also compared with speech from a mynah (Gracula religiosa). Because humans perceive and correctly label psittacine stop consonants despite differences in avian and human articulatory and acoustic parameters, our findings (a) further expand our initial work with vowels [Patterson and Pepperberg, J. Acoust. Soc. Am. 96, 634–648 (1994)], (b) corroborate findings suggesting that the perceptual discontinuities exploited by speech may be accessible to various sensory systems, and (c) challenge the notion that human speech production is a unique process.
Measurement of the reflection matrix of a discontinuity in a duct
Authors: Akoum Mohamed , Ville Jean-Michel
Published: July 2002

An original technique of measuring reflection (or transmission) matrices of duct discontinuities is described. The technique is based on measuring the acoustic pressure by microphone pairs in two closed cross sections of a constant area circular duct, which separates incident and reflected modes after a modal decomposition by a Fourier–Lommel transform. Theory, experimental setup, and data treatment are presented. Then experimental reflection and conversion coefficients at an open duct end for plane wave and higher order modes are presented as an application and compared with analytical results.
The determination of signal coherence length based on signal coherence and gain measurements in deep and shallow water
Authors: Carey William M.
Published: July 2002

Experimental measurements of signal coherence and array signal gain are presented for both deep- and shallow-water sound channels. The signal gain is related to the transverse horizontal coherence length through relationships from the statistical theory of antennas. Signal gain measurements in the transverse direction are proffered as a practical measure of coherence length for both broadband and narrow-band signals. With this technique, measurements at frequencies near 400 Hz are presented and show for the deep-water cases that lengths on the order of 100 wavelengths can be achieved to ranges of 500 km; while in the variable downward refraction conditions of shallow-water waveguides with sand-silt bottoms, lengths on the order of 30 wavelengths to ranges of 45 km are realized. The measurement of broadband and narrow-band coherence is discussed with emphasis on the role of partly coherent noise backgrounds, multipath interference effects, and averaging constraints. Experimental results are interpreted with deep-ocean coherence models consistent with sound scattering from the ocean volume and Gaussian coherence function for the shallow-water waveguide.
Musical instrument identification: A pattern-recognition approach
Authors: Martin Keith D. , Kim Youngmoo E.
Published: July 2002

A statistical pattern-recognition technique was applied to the classification of musical instrument tones within a taxonomic hierarchy. Perceptually salient acoustic features—related to the physical properties of source excitation and resonance structure—were measured from the output of an auditory model (the log-lag correlogram) for 1023 isolated tones over the full pitch ranges of 15 orchestral instruments. The data set included examples from the string (bowed and plucked), woodwind (single, double, and air reed), and brass families. Using 70%/30% splits between training and test data, maximum a posteriori classifiers were constructed based on Gaussian models arrived at through Fisher multiple-discriminant analysis. The classifiers distinguished transient from continuant tones with approximately 99% correct performance. Instrument families were identified with approximately 90% performance, and individual instruments were identified with an overall success rate of approximately 70%. These preliminary analyses compare favorably with human performance on the same task and demonstrate the utility of the hierarchical approach to classification.
Functional neuroimaging of speech perception in six normal and two aphasic subjects
Authors: Mummery C. J. , Ashburner J. , Scott S. K. , Wise R. J. S.
Published: July 2002

This positron emission tomography study used a correlational design to investigate neural activity during speech perception in six normal subjects and two aphasic patients. The normal subjects listened either to speech or to signal-correlated noise equivalents; the latter were nonspeech stimuli, similar to speech in complexity but not perceived as speechlike. Regions common to the auditory processing of both types of stimuli were dissociated from those specific to spoken words. Increasing rates of presentation of both speech and nonspeech correlated with cerebral activity in bilateral transverse gyri and adjacent superior temporal cortex. Correlations specific to speech stimuli were located more anteriorly in both superior temporal sulci. The only asymmetry in normal subjects was a left lateralized response to speech in the posterior superior temporal sulcus, corresponding closely to structural asymmetry on the subjects’ magnetic resonance images. Two patients, who had left temporal infarction but performed well on single word comprehension tasks, were also scanned while listening to speech. These cases showed right superior temporal activity correlating with increasing rates of hearing speech, but no significant left temporal activation. These findings together suggest that the dorsolateral temporal cortex of both hemispheres can be involved in prelexical processing of speech.
Optimized acoustic properties of cellular solids
Authors: Wang Xiaolin , Lu Tian J.
Published: July 2002

The optimized cell size and shape, cell size variations, sample thickness, and air cavity depth behind the sample for best sound absorption performance of air-filled porous materials having simple cell morphologies are studied in this paper. The focus is on cellular foams that are rigidly framed, e.g., aluminum alloy foams and honeycombs. The governing equations of wave propagation are solved by using the point-matching method, and the predictions are compared with known analytical solutions. The effects of cell size variations are studied for Voronoi polygons. A domain-matching method is introduced to obtain the optimal combination of cell size and shape, sample thickness, and cavity depth for selected ranges of frequency. At given porosity, the effect of cell shape on sound absorption is small. The optimized cell size for best sound absorbers is on the order of ∼0.1 mm for practical combinations of sample thickness, cavity depth, and porosity. A random distribution of cell sizes tends to tighten the region where combinations of sample thickness and cavity depth achieve high sound absorption coefficient.
The role of perceived spatial separation in the unmasking of speech
Authors: Freyman Richard L. , Helfer Karen S. , McCall Daniel D. , Clifton Rachel K.
Published: July 2002

Spatial separation of speech and noise in an anechoic space creates a release from masking that often improves speech intelligibility. However, the masking release is severely reduced in reverberant spaces. This study investigated whether the distinct and separate localization of speech and interference provides any perceptual advantage that, due to the precedence effect, is not degraded by reflections. Listeners’ identification of nonsense sentences spoken by a female talker was measured in the presence of either speech-spectrum noise or other sentences spoken by a second female talker. Target and interference stimuli were presented in an anechoic chamber from loudspeakers directly in front and 60 degrees to the right in single-source and precedence-effect (lead-lag) conditions. For speech-spectrum noise, the spatial separation advantage for speech recognition (8 dB) was predictable from articulation index computations based on measured release from masking for narrow-band stimuli. The spatial separation advantage was only 1 dB in the lead-lag condition, despite the fact that a large perceptual separation was produced by the precedence effect. For the female talker interference, a much larger advantage occurred, apparently because informational masking was reduced by differences in perceived locations of target and interference.
A two-frequency acoustic technique for bubble resonant oscillation studies
Authors: Ohsaka K. , Trinh E. H.
Published: July 2002

A two-frequency acoustic apparatus has been developed to study the dynamics of a single gas or vapor bubble in water. An advantage of the apparatus is its capability of trapping a bubble by an ultrasonic standing wave while independently driving it into oscillations by a second lower frequency acoustic wave. For a preliminary application, the apparatus is used to study resonant oscillations. First, near-resonant coupling between the volume and the n=3 shape oscillation modes of air bubbles at room temperature is studied, where n is the mode number. The stability boundary, amplitude versus frequency, of the volume oscillation forms a wedge centered at the resonant frequency, which qualitatively agrees with a theoretical prediction based on a phase-space analysis. Next, the resonant volume oscillations of vapor bubbles are studied. The resonant radius of vapor bubbles at 80 °C driven at 1682 Hz is determined to be 0.7 mm, in agreement with a prediction obtained by numerical simulation.
Enhancement and inhibition of acoustic radiation in spherical cavities
Authors: Ye Zhen
Published: July 2002

Acoustic radiation from a source located inside layered cavities is studied using the transfer matrix method. It is shown that the radiation can be either enhanced or inhibited, depending on the characteristics and the material composition of the cavities. The analysis predicts well-defined spectral peaks and nodes in some cavities. It is found that significant enhancement and inhibition are possible by varying acoustic parameters. The results also show that the strength of the radiating source can be significantly modified due to the presence of layered structures. The link to the similar phenomena in the optical cavities is discussed.
Historical Comments on Stress Relaxation Following Steady Flows Through a Duct or Orifice
Authors: Metzner A. B.
Published: July 2002

The early scientific literature relating to the geometry of a jet of fluid as it emerges from a duct or orifice is considered. This stress-relaxation problem has become variously known as the “Barus effect” or “Merrington phenomenon”. Both of these designations are seen to be incorrect historically and their discontinuance is recommended in favor of a phrase description of the material behavior, such as “extrudate expansion.”
Complexation induced changes of rheological properties of starch systems at different moisture levels
Authors: Conde-Petit Béatrice , Escher Felix
Published: July 2002

Starch, especially the linear amylose fraction, is able to form helical inclusion compounds or complexes with molecules like flavor compounds, fatty acids, and emulsifiers. The effects of starch complexation on rheological properties were studied (a) in aqueous dispersions of 1%–4% starch content, (b) in high-concentration gels of 40% starch content, and (c) in extrusion cooked low moisture starch blends. Complexation was followed by iodine binding capacity of starch and by differential scanning calorimetry. Rheological characterization was based on dynamic and steady shear measurements and on uniaxial force deformation tests. At low starch concentrations, the addition of complexing emulsifiers and flavor compounds induced gelation, provided that enough amylose was solubilized and swollen granules were present. Likewise, freshly prepared high-concentration starch gels with the addition of complexing ligands exhibited higher moduli of deformability than control samples without additives. The sequence of moduli of elasticity became inverse during storage as complexation lowered the rate of amylose retrogradation. Melt viscosity during cooking extrusion increased with the addition of both complexing emulsifiers and noncomplexing triglycerides, while paste viscosity of ground extrudates increased with emulsifiers but not with triglycerides. Influence of starch complexation seems to be parallel for all moisture levels indicating that the main feature is the formation of insoluble amylose complexes which in turn lead to the formation of a firmer network between the dispersed starch granules.
Prevalence and Odds of Depressive and Anxiety Disorders and Symptoms in Children and Adults With Alopecia Areata
Authors: Lauron Sophie , Plasse Camille , Vaysset Marion , Pereira Bruno , D’Incan Michel , Rondepierre Fabien , Jalenques Isabelle
Published: January 2023

Importance

Two recent meta-analyses reported a high prevalence of both anxiety and depression in patients with alopecia areata (AA), as well as a positive association of AA with anxiety and depression, without distinguishing between disorders and symptoms. Yet, depression and anxiety can manifest either as symptoms identified in questionnaires or as specific diagnoses defined by Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) or International Statistical Classification of Diseases and Related Health Problems, Tenth Revision criteria.

Objective

To perform a large meta-analysis separating the prevalence of depressive and anxiety disorders from that of depressive and anxiety symptoms in patients with AA.

Data Sources

PubMed, ScienceDirect, the Cochrane Library, Embase, and PsycINFO databases were searched from inception through August 1, 2020.

Study Selection

Studies that contained data on the prevalence of depressive or anxiety disorders or symptoms were included.

Data Extraction and Synthesis

The Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines were used. Pooled prevalence was calculated with a random effects model meta-analysis that took into account between- and within-study variability. Meta-regressions were used to study the association between variations in prevalence and study characteristics.

Main Outcomes and Measures

The prevalence of depressive and anxiety disorders and symptoms in patients with AA.

Results

Thirty-seven articles (29 on depression and 26 on anxiety) that met the inclusion criteria were identified. By distinguishing between disorders and symptoms, the prevalence of both depressive disorders (9%) and unspecified anxiety disorders (13%) in patients with AA was shown to be greater than that in the general population. The prevalence and odds ratio (OR) of depressive disorders (prevalence, 9%; OR, 1.38) and anxiety disorders of which each category had been specifically studied (prevalence, 7%-17%; OR, 1.51-1.69) were markedly lower than that of depressive symptoms (prevalence, 37%; OR, 2.70) and anxiety symptoms (prevalence, 34%; OR, 3.07). Meta-regressions showed that variations in prevalence were mainly associated with methodological differences between studies.

Conclusions and Relevance

In this systematic review and meta-analysis, the separate analyses showed that 7% to 17% of patients with AA had depressive or anxiety disorders that require psychiatric care, including specific medication. Additionally, more than one-third of patients had symptoms that are warning signs and that need monitoring because they can develop into disorders.
(111)‐Oriented Growth and Acceptor Doping of Transparent Conductive CuI:S Thin Films by Spin Coating and Radio Frequency‐Sputtering
Authors: Geng Fangjuan , Wang Liangjun , Stralka Tillmann , Splith Daniel , Ruan Siyuan , Yang Jialin , Yang Lei , Gao Gang , Xu Liangge , Lorenz Michael , Grundmann Marius , Zhu Jiaqi , Yang Chang
Published: January 2023

Anion doping is an efficient method for modifying the electrical property of the p‐type semiconductor CuI. However, adjustment of the hole density is still challenging. Using sputtering and spin coating techniques, well‐controlled S‐doping of CuI thin films has been realized. The spin‐coated samples present a single (111) out‐of‐plane orientation and very high crystallinity, which is comparable with previously reported epitaxial CuI thin films. The sputtered thin films have advantages in surface morphology and conductivity. Substituting S for I can achieve efficient acceptor doping of CuI for both the physical and chemical growth methods. The highest conductivity of CuI appears at 2.0 at% of S doping, and the doping efficiency is influenced by the self‐compensation effect.
Highly Sensitive and Durable, Triboelectric Based Self‐Powered Nanosensor for Boundary Detection in Sports Event
Authors: Liu Haisheng , Cao Jie , Feng Shuai , Cheng Guanggui , Zhang Zhongqiang , Ding Jianning
Published: January 2023

Assisted adjudication of sports activities and events is becoming more intelligent with the rapid development of the Internet of Things (IoTs). Sensors such as pressure sensors and image sensors have been widely used in sports events, but their durability and energy supply are still challenge. Herein, a novel boundary detection sensor based on hyperelastic triboelectric nanogenerator (H‐TENG) for intelligent boundary detection is proposed. The stress–strain of a tennis ball colliding with H‐TENG at high speed and the sensing stability are investigated by simulation analysis and experimental validation. The pressure sensitivity of 2.96 V kPa−1 is achieved with excellent linearity (R2 = 0.957082) at the pressure of 2.8–13 kPa. And at the velocity of 2–4.47 m s−1, the velocity sensitivity reaches ‐10.76 V (m s−1)−1 with excellent linearity (R2 = 0.948758). Furthermore, a four‐channels signal acquisition system is constructed for enhancing the detection accuracy, and the response times of signal feedback are less than 45 ms. This work not only provides a novel approach for intelligent boundary detection in sporting events, but also demonstrates its promising applications in multiple challenges and quick penalties in sports competitions, as well as in intelligent and digital training of athletes.
Simultaneous Detection of L‐Lactate and D‐Glucose Using DNA Aptamers in Human Blood Serum**
Authors: Huang Po‐Jung Jimmy , Liu Juewen
Published: January 2023

L‐lactate is a key metabolite indicative of physiological states, glycolysis pathways, and various diseases such as sepsis, heart attack, lactate acidosis, and cancer. Detection of lactate has been relying on a few enzymes that need additional oxidants. In this work, DNA aptamers for L‐lactate were obtained using a library‐immobilization selection method and the highest affinity aptamer reached a Kd of 0.43 mM as determined using isothermal titration calorimetry. The aptamers showed up to 50‐fold selectivity for L‐lactate over D‐lactate and had little responses to other closely related analogs such as pyruvate or 3‐hydroxybutyrate. A fluorescent biosensor based on the strand displacement method showed a limit of detection of 0.55 mM L‐lactate, and the sensor worked in 90 % serum. Simultaneous detection of L‐lactate and D‐glucose in the same solution was achieved. This work has broadened the scope of aptamers to simple metabolites and provided a useful probe for continuous and multiplexed monitoring.
Towards Axially Chiral Pyrazole‐Based Phosphorus Scaffolds by Dipeptide‐Phosphonium Salt Catalysis
Authors: Wu Jia‐Hong , Tan Jian‐Ping , Zheng Jia‐Yan , He Jiajia , Song Zhenlei , Su Zhishan , Wang Tianli
Published: January 2023

Given the comparatively lower rotational barriers, the catalytic asymmetric construction of axially chiral biaryl structures, especially those containing a five‐membered heterocycle, still remains a challenge. Herein, we described a general and modular protocol to access atropisomeric arylpyrazole scaffolds containing a phosphorus unit by a dipeptide phosphonium salt catalyzed reaction involving an oxidative central‐to‐axial chirality conversion. This reaction features excellent yields and enantioselectivities, broad substrate scope, and a low catalyst loading, delivering axially chiral phosphine compounds.
Solvent‐Controlled Quadruple Catenation of Giant Chiral [8+12] Salicylimine Cubes Driven by Weak Hydrogen Bonding
Authors: Wagner Philippe , Rominger Frank , Gross Jürgen H. , Mastalerz Michael
Published: January 2023

Mechanically interlocked structures are fascinating synthetic targets and the topological complexity achieved through catenation offers numerous possibilities for the construction of new molecules with exciting properties. In the structural space of catenated organic cage molecules, only few examples have been realized so far, and control over the catenation process in solution is still barely achieved. Herein, we describe the formation of a quadruply interlocked catenane of giant chiral [8+12] salicylimine cubes. The formation could be controlled by the choice of solvent used in the reaction. The interlocked structure was unambiguously characterized by single crystal X‐ray diffraction and weak hydrogen bonding was identified as a central driving force for the catenation. Furthermore, scrambling experiments using partially deuterated cages were performed, revealing that the catenane formation occurs through mechanical interlocking of preformed single cages.
Proton‐Conductive Supramolecular Hydrogen‐Bonded Organic Superstructures for High‐Performance Zinc‐Organic Batteries
Authors: Song Ziyang , Miao Ling , Ruhlmann Laurent , Lv Yaokang , Li Liangchun , Gan Lihua , Liu Mingxian
Published: January 2023

With fast (de)coordination kinetics, the smallest and the lightest proton stands out as the most ideal charge carrier for aqueous Zn‐organic batteries (ZOBs). Hydrogen‐bonding networks with rapid Grotthuss proton conduction is particularly suitable for organic cathodes, yet not reported. We report the supramolecular self‐assembly of cyanuric acid and 1,3,5‐triazine‐2,4,6‐triamine into organic superstructures through in‐plane H‐bonds and out‐of‐plane π‐π interaction. The supramolecular superstructures exhibit highly stable lock‐and‐key H‐bonding networks with an ultralow activation energy for protonation (0.09 eV vs. 0.25 eV of zincification). Then, high‐kinetics H+coordination is prior to Zn2+into protophilic C=O sites via a two‐step nine‐electron reaction. The assembled ZOBs show high‐rate capability (135 mAh g−1at 150 A g−1), high energy density (267 Wh kg−1cathode) and ultra‐long life (50 000 cycles at 10 A g−1), becoming the state‐of‐the‐art ZOBs in comprehensive performances.
Systematic analysis of the Rayleigh–Wood anomalies and the symmetry relations of 2D‐periodic nanostructures by imaging spectroscopic ellipsometry
Authors: Okano Shun , Duwe Matthias , Sivis Murat , Ueda Gen , Owa Tetsuhiro , Ikushima Kenji
Published: January 2023

Periodic arrays of metallic nanostructures were fabricated by electron beam lithography and studied by means of spectroscopic imaging ellipsometry in the near infrared to ultraviolet spectral ranges. The sample consists of gold nanodisc and nanorod gratings on a silicon substrate. Spectroscopic imaging ellipsometry, allowing for the simultaneous observation of all gratings with microscopic resolution, was used to systematically analyze the varying grating and nanostructure parameters. The ellipsometric spectra obtained for a full in‐plane sample rotation proved to be a highly sensitive measure of the gratings’ Rayleigh–Wood anomalies. Their dependence on the sample azimuth was in excellent agreement with the Rayleigh lines calculated from the grating parameters and could be tracked for both the ambient‐to‐grating and the grating–substrate interfaces. Contrary to other studies on similarly sized nanoparticle arrays, we found no indication of localized plasmon resonance in the visible range of the spectrum, but only a weak NIR response truncated by the Rayleigh lines. Finally, the symmetry of the structures was investigated by imaging Mueller‐matrix measurements.