bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring patients’ perceptions on their functional abilities: validation of the Haemophilia Activities List
Authors: VAN GENDEREN F. R. , WESTERS P. , HEIJNEN L. , DE KLEIJN P. , VAN DEN BERG H. M. , HELDERS P. J. M. , VAN MEETEREN N. L. U.
Published: January 2006

Summary.  Recently, the Haemophilia Activities List (HAL), a haemophilia‐specific self‐assessment questionnaire to assess a patient's self‐perceived functional ability, was introduced and a limited pilot study warranted its further development. The present study finalizes the HAL and assesses the convergent and construct validity, as well as the internal consistency of its definitive version. Three questionnaires (HAL, Dutch‐Arthritis Impact Measurement Scales 2 and the Impact on Participation and Autonomy questionnaire) were completed by 127 patients with severe haemophilia (<1% clotting activity), as well as four performance tests (button test, 50 metre walking test, timed‐up‐and‐go test and figure‐8 walking test). After removal of 15 non‐informative items from the provisional HAL, three components within the questionnaire were identified (upper extremity activities, basic lower extremity activities and complex lower extremity activities). The internal consistency of these components was high (Cronbach's α = 0.93–0.95), as was internal consistency for the seven domains of the HAL (α = 0.61–0.96). The convergent validity of the HAL when compared to the other two questionnaires was good (r = 0.47–0.84). The construct validity of the HAL when compared to the four performance tests was generally lower (r = 0.23–0.77). The final version of the HAL has good internal consistency and convergent validity and gives the clinician insight into a patient's self‐perceived ability to perform activities of daily life. It is likely that self‐assessment instruments (questionnaires) and performance tests consider different concepts of functional health status and it is therefore recommended that both types are included when clinicians assess a patient's functional abilities.
Practice patterns in haemophilia A therapy – global progress towards optimal care
Authors: GERAGHTY S. , DUNKLEY T. , HARRINGTON C. , LINDVALL K. , MAAHS J. , SEK J.
Published: January 2006

Summary.  This paper reports the findings of a global survey of practice patterns for the management of patients with haemophilia A. A total of 147 haemophilia treatment centres worldwide responded to the questionnaire, supplying data for 16 115 patients with haemophilia A. From these responses, 38% (range: 25–48%) of patients were under 18 years old. Almost half (47%) of patients were reported to have mild or moderate haemophilia A, 48% had severe haemophilia A (no inhibitor) and 5% were inhibitor patients. Less than half of patients with severe haemophilia A received prophylactic therapy (37%, excluding inhibitor patients) and 54% received on‐demand treatment; the remaining 9% were inhibitor patients. Primary prophylaxis rates for severe haemophilia ranged from 73% in Sweden to 17% in the USA. Most respondents (80%) ranked infrequent bleeds as one of the top five reasons for not administering prophylactic treatment, followed by venous access (60%) and cost (45%). Of patients with severe haemophilia (non‐inhibitor), 32% on primary prophylaxis and 27% on secondary prophylaxis had indwelling catheters. Risk of infection and the patient's inability to maintain the line were the key concerns cited by nurses relating to venous access. The mean ratio of nurses to patients with haemophilia A was 1:69 and nurses felt that they were either fully (26%) or mostly (45%) autonomous in assessment and treatment decisions. Results from this current survey suggest that worldwide research should be continued so as to improve outcomes through the identification of optimal treatment protocols for the management of haemophilia A.
Severe malaria in children in areas with low, moderate and high transmission intensity in Uganda
Authors: Idro R. , Aloyo J. , Mayende L. , Bitarakwate E. , John C. C. , Kivumbi G. W.
Published: January 2006

Objectives  Age and transmission intensity are known to influence the manifestations of severe falciparum malaria in African children. However, it is unclear how specific clinical features such as seizures, impairment of consciousness, or respiratory distress vary with the parasite load and transmission intensity. We examined how the peripheral parasite load varies with transmission intensity and how this influences the symptoms and manifestations of severe malaria in children under 5 years in three areas with different malaria transmission intensity across Uganda.

Methods  We consecutively recruited 617 children with severe malaria presenting to three hospitals in areas with very low (51), moderate (367) and very high (199) transmission intensities and compared the age, admission parasite density and proportions of patients with different manifestations of severe disease.

Results  The median age (months) was inversely proportional to transmission intensity and declined with rising transmission (26.4 in very low, 18.0 in moderate and 9.0 under very high transmission). The highest proportion of patients reporting previous malaria admissions came from the area with moderate transmission. The geometric mean parasite density (18 357, 32 508 and 95 433/μl) and the proportion of patients with seizures (13.7%, 36.8% and 45.7%, P < 0.001) from very low, moderate and very high transmission respectively, increased with rising transmission. A linear increase with transmission was also observed in the proportion of those with repeated seizures (9.8%, 13.4% and 30.2%, P < 0.001) or impaired consciousness (7.8%, 12.8% and 18.1%, P = 0.029) but not respiratory distress. The proportion of patients with severe anaemia (19.6%, 24.8% and 37.7%, P = 0.002) mirrored that of patients with seizures.

Conclusions  These findings suggest that heavy Plasmodium falciparum parasitaemia may be important in development of seizures, severe malarial anaemia and impaired consciousness in children under 5 years of age but may not be important in the development of respiratory distress.
Cutaneous leishmaniasis: successful treatment with itraconazole
Authors: Consigli Javier , Danielo Cristian , Gallerano Verónica , Papa Mariana , Guidi Andrés
Published: January 2006

Background  Leishmaniasis is a disease produced by several species of protozoa of the Leishmania genus. These protozoa are injected into the human bloodstream by sandflies. The symptomathology, either cutaneous, mucocutaneous or visceral, depends on the infective species and the immune status of the patient. Antimonial drugs are the mainstay treatment for all the clinical forms of the disease. Amphotericin B is the second‐choice drug.

Methods  We report two clinical cases of cutaneous leishmaniasis treated with itraconazole. One case was a relapsing form unresponsive to conventional therapy.

Results  Both patients achieved fast resolution of their lesions with no secondary effects.

Conclusions  Itraconazole may be a valid option for the treatment of cutaneous leishmaniasis, mainly in those cases unresponsive to conventional drugs.
“More is missed by not looking than by not knowing”[Thomas McCrae, 1870–1935]
Authors: Wolf Ronni , Orion Edith , Marcos Batsheva , Matz Hagit
Published: January 2006

Case 1  A 19‐year‐old woman presented with a black crust on one part of the tattoo on her right leg (Fig. 1) which appeared after laser‐assisted hair removal by an alexandrite laser (755 nm).

A depressed black crust with an erythematous halo on the black part of the tattoo in Case 1, 2 weeks after laser hair removal

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Case 2  A 28‐year‐old man underwent laser‐assisted hair removal from his back and shoulders by an alexandrite laser (755 nm), after which he developed a burn on part of the tattoo on his right shoulder and was left with an atrophic scar (Fig. 2).

Atrophic, stria‐like scar at the site of the black tattoo in Case 2, 6 months after laser hair removal

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Pravastatin‐induced lichenoid drug eruption
Authors: Pua Vernon SC , Scolyer Richard A , Barnetson Ross StC
Published: January 2006

A 64‐year‐old woman presented with diffuse and numerous pigmented macules on her face and upper back. Histopathological examination of a skin punch biopsy of the rash showed a lichenoid dermatitis. The most likely offending drug was pravastatin. Cessation of pravastatin resulted in gradual fading of the pigmentation. 3‐Hydroxy‐3‐methylglutaryl coenzyme A reductase inhibitors have previously been reported to cause lichenoid drug eruptions.
Alar anaesthesia: A kinder method
Authors: Stanway Amy , Salmon Paul
Published: January 2006

Local infiltration of anaesthetic in the ala of the nose is very uncomfortable for most patients. This is an area frequently operated on by dermatosurgeons under local anaesthesia as it is a common site for non‐melanoma cutaneous malignancies. A simple method is described of providing more pleasant local anaesthesia for patients undergoing alar surgery by using nerve blocks prior to local infiltration.
Butterfly extinctions in European states: do socioeconomic conditions matter more than physical geography?
Authors: Konvicka Martin , Fric Zdenek , Benes Jiri
Published: January 2006

Aim To distinguish the effects of physical geography and socioeconomic conditions on the extinction of butterflies in European states, and to compare patterns influencing extinctions with patterns influencing species richness.

Location Europe.

Method Per‐state species richness and extinctions were taken from theRed Data Book of European Butterflies, and their relationships with physical geography and socioeconomic predictors were analysed using regression analysis. Two hypothesis were explored: (1) extinctions are related primarily to identical physical geography factors that influence species richness; and (2) extinctions are influenced primarily by human pressure on natural biotopes and follow correlates of modern land use.

Results Extinctions and richness are not correlated. Richness increased towards low latitudes and with biotope and topographic heterogeneity, and decreased in states affected by Quaternary glaciation and on islands. The only socioeconomic correlate was human density, exhibiting a weak negative effect. Extinctions were negatively correlated with area and with biotope and topographic heterogeneity. They peaked in regions with mild climate in central latitudes. The strongest socioeconomic correlate was high density of railways, interpreted as a proxy of early industrialization. Further correlates were human density and urban employment.

Main conclusion Topographic and biotope heterogeneity predicts both high species richness and low extinction rates. Losses of butterflies result from a complex interplay of geography and relatively recent economic history, as low topographic heterogeneity and flat relief favoured the early advent of industrialization and intensive land use.
Social Capital, Cognition, and Entrepreneurial Opportunities: A Theoretical Framework
Authors: De Carolis Donna Marie , Saparito Patrick
Published: January 2006

Entrepreneurship—the recognition and exploitation of opportunities—is valuable within organizations as well as in the establishment of new ventures. Some studies have addressed the issue why some individuals take advantage of opportunities and some do not. While some studies find that psychological variables, personality traits and demographic factors may distinguish entrepreneurial activity, these findings are equivocal. Other research has looked to the importance of social capital and network ties to new venture creation. Yet, there is little discussion regarding the possibility that social capital and personal factors interact and influence entrepreneurial behavior.

 Drawing from social cognitive theory (Augoustinos & Walker, 1995; Fiske & Taylor, 1984; Bandura, 1986; Wood & Bandura, 1989) this paper advances a model suggesting that entrepreneurial behavior is a result of the interplay of environments (i.e., social networks) and certain cognitive biases in entrepreneurs. We propose that both individual cognition and social capital are important in understanding entrepreneurial behavior. If the domain of entrepreneurship is “…the nexus of two phenomena: the presence of lucrative opportunities and the presence of enterprising individuals” (Shane & Venkataraman, 2000) then our model suggests an explanation of this nexus through exploring how both external (i.e., social capital) and internal factors (i.e., cognition) affect why some people and not others exploit opportunities.
Avoidance of Palpable Corporal Fibrosis Due to Priapism with Upregulators of Nitric Oxide
Authors: Rajfer Jacob , Gore John L. , Kaufman Jeffrey , Gonzalez-Cadavid Nestor
Published: January 2006

Introduction

Recent evidence suggests that blocking inducible nitric oxide (NO) synthase in the penis may exacerbate fibrotic processes and that application of medications known to increase NO in tissues may prevent fibrosis.

Aim

To report the use of an antifibrotic regimen consisting of medications known to upregulate NO production in two patients with refractory priapism.

Methods

Two patients presented with priapism of greater than 48-hour duration. After corporal aspiration/irrigation and shunting procedures failed, both were prescribed a daily antifibrotic regimen comprising the phosphodiesterase inhibitors pentoxifylline and sildenafil, and the NO precursor, l-arginine.

Results

At 1 year, both patients were found to have supple corpora without evidence of corporal fibrosis.

Conclusions

An antifibrotic regimen consisting of upregulators of NO production may ameliorate the corporal fibrosis associated with recalcitrant priapism.
A New Evaluation Concept and its Measurement: “Male Sexual Anticipating Cognitions”
Authors: Bonierbale Mireille , Clement Audrey , Loundou Anderson , Simeoni Marie-Christine , Barrau Karine , Hamidi Karim , Apter Michael J. , Lançon Christophe , Auquier Pascal
Published: January 2006

Context

The development of sex-active drugs justifies the use of scales for evaluating changes induced by such forms of therapy. Among the tools available for evaluating erectile dysfunction (ED), the International Index of Erectile Function is the most widely used. Analysis of the scientific literature shows that these instruments remain primarily focused on functional aspects of ED. The vulnerability factors involved in ED are mainly based upon organic characteristics, e.g., age, cardiovascular diseases, or diabetes, but the psychological factors involved in the occurrence and maintenance of ED are less studied.

Objective

This conclusion led us to develop a French self-administered instrument, based on patients’ subjective sexual experiences, to evaluate “male sexual anticipating cognitions,” using Apter's reversal theory as a framework.

Design, Setting, and Patients

We present here the first stages of the development of this new instrument. We carried out semistructured, one-to-one interviews with patients with psychogenic ED and patients with mixed ED. Eighteen one-to-one interviews were held in several urologic/andrologic and psychiatric sexologist services. Interviews were continued until the required information was obtained. Analyses of the content were performed to generate items for the new instrument.

Results

Dimensions isolated were those of (a) sexual beliefs; (b) metamotivational modes; and (c) dysfunctional coping. Pools of items are currently being analyzed by 108 experts (psychologists, sexologists, andrologists, urologists) to determine if additional items are required. The acceptability and the comprehensiveness of this preliminary questionnaire will be tested by 320 patients in a multicentric study, to produce a shorter questionnaire featuring the most relevant items. Once validated, this multidimensional instrument could be used to assess treatment efficacy of the mixed and psychogenic components of ED.
Paraffinoma and Ulcer of the External Genitalia After Self-Injection of Vaseline
Authors: Akkus Emre , Iscimen Aydin , Tasli Levent , Hattat Halim
Published: January 2006

We present a 42-year-old circumcised man with a 10-cm firm, irregular penile mass associated with multiple penile ulcers, voiding difficulty, and erectile dysfunction. He reluctantly admitted that 8 months previously, he had multiple mineral-oil (vaseline) self-injections to the penis, for penile enlargement purposes. Histopathological examination revealed the condition was consistent with mineral-oil granuloma (paraffinoma). The patient did not accept surgical intervention; therefore, we performed local therapy (intralesional triamcinolone) and hot-water baths. Paraffinoma results from mineral-oil injections. Such injections are rare; however, they are still being performed in some countries in Eastern Europe and the Far East such as Korea. Increased physician and public awareness are needed for prevention and treatment of complications of this physically and psychologically debilitating and destructive problem.
Penile Girth Augmentation Using Flaps “Shaeer's Augmentation Phalloplasty”: A Case Report
Authors: Shaeer Osama , Shaeer Kamal
Published: January 2006

Introduction

Current girth augmentation techniques rely either on liposuction/injection or on the use of dermal fat grafts. These procedures have serious disadvantages, including regression in gained size, deformities, irregular contour, and asymmetry. Ideally, the augmentation technique should ensure durability and symmetry. This case report describes the first application of a flap (superficial circumflex iliac artery island flap) in penile girth augmentation.

Materials and Methods

The superficial circumflex iliac vessels were identified and the groin flap was elevated from lateral to medial, rotated toward the penis, and tunneled into a penopubic incision. It was wrapped around the penis short of the corpus spongiosum and insinuated under the glans.

Results

Six months after surgery, the patient had an erect girth of 19.5 cm and a flaccid girth of 16.5 cm, compared with 11 cm and 7 cm, respectively, before surgery, thus maintaining the intraoperative girth gain. The outer surface felt smooth with no lobulation. The size of the glans was proportionate to the shaft's girth.

Conclusion

This case report shows that the application of flaps in penile girth augmentation may provide a reliable alternative to the currently applied techniques. Glans flaring promotes the aesthetic results and is applicable with other techniques of penile girth augmentation.
Use of Rigid Spherical Inclusions in Young’s Moduli Determination: Application to DNA-Crosslinked Gels
Authors: Lin David C. , Yurke Bernard , Langrana Noshir A.
Published: January 2006

Current techniques for measuring the bulk shear or elastic (E) modulus of small samples of soft materials are usually limited by materials handling issues. This paper describes a nondestructive testing method based on embedded spherical inclusions. The technique simplifies materials preparation and handling requirements and is capable of continuously monitoring changes in stiffness. Exact closed form derivations of E as functions of the inclusion force-displacement relationship are presented. Analytical and numerical analyses showed that size effects are significant for medium dimensions up to several times those of the inclusion. Application of the method to DNA-crosslinked gels showed good agreement with direct compression tests.
Computational Studies of Shape Memory Alloy Behavior in Biomedical Applications
Authors: Petrini Lorenza , Migliavacca Francesco , Massarotti Paolo , Schievano Silvia , Dubini Gabriele , Auricchio Ferdinando
Published: January 2006

Background: Nowadays, shape memory alloys (SMAs) and in particular Ni–Ti alloys are commonly used in bioengineering applications as they join important qualities as resistance to corrosion, biocompatibility, fatigue resistance, MR compatibility, kink resistance with two unique thermo-mechanical behaviors: the shape memory effect and the pseudoelastic effect. They allow Ni–Ti devices to undergo large mechanically induced deformations and then to recover the original shape by thermal loading or simply by mechanical unloading. Method of approach: A numerical model is developed to catch the most significant SMA macroscopic thermo-mechanical properties and is implemented into a commercial finite element code to simulate the behavior of biomedical devices. Results: The comparison between experimental and numerical response of an intravascular coronary stent allows to verify the model suitability to describe pseudo-elasticity. The numerical study of a spinal vertebrae spacer, where the effects of different geometries and material characteristic temperatures are investigated, allows to verify the model suitability to describe shape memory effect. Conclusion: the results presented show the importance of computational studies in designing and optimizing new biomedical devices.
Sound propagation in a turbulent atmosphere near the ground: An approach based on the spectral representation of refractive-index fluctuations
Authors: Salomons Erik M. , Ostashev Vladimir E. , Clifford Steven F. , Lataitis Richard J.
Published: January 2006

A new, rigorous approach is presented for the computation of the fluctuating field of a monopole source in a nonrefracting, turbulent atmosphere above a ground surface. The time-averaged sound pressure level is considered, as well as statistical distributions of the sound pressure level. The computation is based on the Rytov solution of the wave equation for a turbulent medium, evaluated for the half-space above the ground surface. The solution takes into account the ground reflection of scattered waves, which has been neglected in previous work on this subject. The present approach is based on a Fourier–Stieltjes representation of refractive-index fluctuations, and makes use of a turbulent image atmosphere to account for the ground reflection of scattered waves. This approach is rigorous only for a rigid ground surface, but it is shown that it also yields a good approximation for a finite-impedance ground surface. The accuracy of the solution is demonstrated by comparison with results of numerical computations with the parabolic equation method for a turbulent atmosphere. The assumption of a nonrefracting atmosphere implies that direct application of the solution is limited to propagation over relatively small distances. However, this study can also be considered as a basis for a generalized solution for a downward refracting atmosphere, which can be applied for larger propagation distances.
Elastic constants determination of anisotropic materials from phase velocities of acoustic waves generated and detected by lasers
Authors: Reverdy F. , Audoin B.
Published: January 2006

This paper describes a method which allows the synthesis of acoustic plane waves by means of laser ultrasonic techniques. When a laser line source radiates at the surface of an anisotropic material, intricate effects are observed on signals obtained by transmission experiments. The material characterization from such a set of signals is not a trivial task since it requires correctly selecting the data necessary for the elastic constants determination, by distinguishing them from all the parasitic phenomena. In the present paper, it is shown that a judicious sum of signals obtained for various positions of the line source at the surface of a sample leads to the synthesis of an acoustic plane wave for which the odd phenomena disappear. Moreover, by applying a constant delay between the various signals, acoustic plane waves can be synthesized with varied refracted angles. One of the advantages of this technique is to offer convenient access to the phase velocity, providing an easier determination of the elastic constants. This method is successively applied to recover the stiffness coefficients of a silicon crystal and of a composite material. The good agreement between the so-recovered elastic constants and values given by other processes shows the contribution of such a method in the field of material characterization.
The design, fabrication, and measured acoustic performance of a 1–3 piezoelectric composite Navy calibration standard transducer
Authors: Benjamin Kim C. , Petrie Sheridan
Published: January 2006

The design, fabrication, and acoustic calibration of a new 1–3 piezoelectric composite-based U.S. Navy standard (USRD-F82) are presented. The F82 dual array/parametric mode projector may be used as a reciprocal linear transducer, or may be used to exploit the nonlinear properties of the water to produce highly directional acoustic beams (4 to 3 deg) at relatively low frequencies (5 to 50 kHz, respectively). As a result of its wide bandwidth, a broad range of primary as well as secondary frequencies of operation is possible. In the linear mode of operation the transducer provides two separate arrays to be addressed topside for either transmit or receive applications. The two circular apertures are centered on the acoustic axis and have active diameters of 22.8 cm (9 in.) and 5.1 cm (2 in.). The smaller array aperture could be used to obtain broader acoustic beams at relatively high frequencies. Due to the absence of air-filled pressure release components, the transducer will operate over most ocean pressures and temperatures. A general description of the 1–3 piezoelectric composite-based transducer configuration and measured performance is presented.
Vocal behavior of male sperm whales: Why do they click?
Authors: Jaquet Nathalie , Dawson Stephen , Douglas Lesley
Published: January 2006

Off Kaikoura, New Zealand, we recorded individually identified male sperm whales (Physeter macrocephalus) for entire dive cycles in order to investigate vocal behavior of individual whales and to examine possible functions of sperm whale clicks. In our study, sperm whales were almost always silent at the surface. They consistently started clicking within 25 s after fluking-up and diving. During the first 10 s of clicking, interclick intervals were significantly correlated with water depths at the location of fluke-up. The first “creak” was produced on average 7.5 min into a dive. Interclick intervals usually decreased substantially before clicks turned into “creaks.” The highest click rate recorded in this study was 90.9 click/s, and clicks-within-creaks were much shorter than “usual clicks” (mean of 3.6 ms versus 17 to 30 ms). The number of creaks per minute of dive and the length of a dive were significantly correlated. On average, sperm whales were silent for the last 3.6 min before surfacing. Short sequences of “surface clicks” (3 to 8 metallic clicks with mean interclick interval of 5.5 s) were often produced at the end of a dive (in 57% of the dives), but their function remains puzzling. The results of this study suggest that usual clicks and creaks are both used for echolocation purposes, the former to gather information about acoustically reflective features and the latter to detect prey.
A cross-language comparison of /d /–/ð / perception: Evidence for a new developmental pattern
Authors: Polka Linda , Colantonio Connie , Sundara Megha
Published: January 2006

Previous studies have shown that infants perceptually differentiate certain non-native contrasts at 6–8 months but not at 10–12 months of age, whereas differentiation is evident at both ages in infants for whom the test contrasts are native. These findings reveal a language-specific bias to be emerging during the first year of life. A developmental decline is not observed for all non-native contrasts, but it has been consistently reported for every contrast in which language effects are observed in adults. In the present study differentiation of English /d–ð/ by English- and French-speaking adults and English- and French-learning infants at two ages (6–8 and 10–12 months) was compared using the conditioned headturn procedure. Two findings emerged. First, perceptual differentiation was unaffected by language experience in the first year of life, despite robust evidence of language effects in adulthood. Second, language experience had a facilitative effect on performance after 12 months, whereas performance remained unchanged in the absence of specific language experience. These data are clearly inconsistent with previous studies as well as predictions based on a conceptual framework proposed by Burnham [Appl. Psycholing. 7, 201–240 (1986)]. Factors contributing to these developmental patterns include the acoustic properties of /d–ð/, the phonotactic uniqueness of English /ð/, and the influence of lexical knowledge on phonetic processing.
Age-related changes in detecting a mistuned harmonic
Authors: Alain Claude , McDonald Kelly L. , Ostroff Jodi M. , Schneider Bruce
Published: January 2006

The effects of age on discriminating simultaneous sounds were investigated by comparing the hearing threshold in detecting a mistuned harmonic in young, middle-aged, and older adults. The stimuli were complex sounds containing multiple harmonics, one of which could be “mistuned” so that it was no longer an integer multiple of the fundamental. Older adults had higher thresholds than middle-aged or young adults. The effect of age was greater for short than for long duration sounds and remained even after controlling for hearing sensitivity. The results are consistent with an age-related decline in parsing simultaneous auditory events, which may contribute to the speech perception difficulties in the elderly.
Improved description of shock wave evolution in media with frequency power law dependent attenuation
Authors: Wallace Kirk D. , Holland Mark R. , Miller James G.
Published: January 2006

A recent article by Kashcheeva et al. considers the effect of dispersion on waveform distortion and shock propagation [Acoust. Phys. 46, 170–177 (2000)]. The authors determine the dispersion from knowledge of the host material’s attenuation properties and a nearly local form of the Kramers–Krönig relations published by our laboratory in 1978. Recent work by our laboratory and others has shown that this original nearly local approximation overestimates the actual dispersion when the frequency power law describing the attenuation deviates from unity. The present letter illustrates the impact of using the exact (nonlocal) Kramers–Krönig relations on shock propagation in media with attenuation obeying a frequency power law ranging from 0–2.
Microphone array signal processing with application in three-dimensional spatial hearing
Authors: Bai Mingsian R. , Lin Chenpang
Published: January 2006

Microphone arrays are known to enhance the directionality and signal-to-noise ratio (SNR) over single-channel sensors. This is considered beneficial in many applications such as video-conferencing systems and hearing aids. However, this advantage comes at the price of the sensation of spatial hearing. The spatial cues due to diffractions of the head and torso are lost if the array is not fitted in the ears. In this paper we present a system that incorporates binaural hearing synthesis into array signal processing, in an attempt to recover the three-dimensional sound image that a human listener would naturally perceive. In the system, the superdirective beamformer is exploited to estimate the direction of arrival (DOA) of the incoming sound. The spatial sound image is restored by steering the beam to the direction found in the DOA session and filtering the array output with the corresponding Head Related Transfer Functions (HRTF). The algorithms have been implemented in real-time fashion using a digital signal processor. Objective and subjective experiments were performed to validate the proposed system. The experimental results showed that the accurate localization of the sound source is achievable using the array system.
Phase-space beam summation analysis of rough surface waveguide
Authors: Gordon Goren , Heyman Ehud , Mazar Reuven
Published: January 2006

A Gaussian beam summation (GBS) formulation is introduced for a doubly rough boundary waveguide, wherein the coherent and incoherent scattered fields are decomposed into a discrete phase-space summation of Gaussian beams (GB) that emanate from the rough surfaces in all directions. The scheme involves deterministic GB propagators and stochastic GB-to-GB (GB2GB) scattering matrices for the coherent and incoherent fields, where each scattered beam is propagated inside the waveguide and is scattered again from the rough boundaries. The GB2GB matrices are calculated from the statistical moments of the scattering amplitude, which are given either analytically or empirically. An analytical and numerical example for a waveguide with weak boundary roughness is presented and discussed. The formulation reveals explicitly the phase-space footprint of the stochastic multiple scattering process at the rough boundaries, thus providing a cogent physical interpretation and an effective mathematical representation to the field. The formulation also accommodates the receiver’s pattern in the same phase-space format. Bistatic reverberations inside a rough surface waveguide as a function of the range and of the source and the receiver directions are thus examined as an implementation example.
On the interaction of counterpropagating acoustic waves in resonant rods composed of materials with hysteretic quadratic nonlinearity
Authors: Gusev Vitalyi
Published: January 2006

An ordinary inhomogeneous integrodifferential equation for the profile of the acoustic wave in a resonant rod, composed of a material with hysteretic quadratic nonlinearity, is derived. It explicitly takes into account the interaction of the counterpropagating acoustic waves. It also incorporates the boundary conditions in the sense that all possible solutions of the equation satisfy the appropriate boundary conditions at the ends of the rod.
Beating frequency and amplitude modulation of the piano tone due to coupling of tones
Authors: Cartling Bo
Published: January 2006

The influence on a piano tone from weak coexcitation of damped adjacent tones due to coupling via the bridge is studied. The frequency and amplitude modulation of the sound resulting from coexcitation of one strong and one or two weak tones is analyzed. One weak tone causes frequency and amplitude modulation of the sound, and two weak tones produce beating frequency and amplitude modulation, where the beatings of the two modulations are of opposite phase. By digital recording of the sound of piano tones, the appearance of these phenomena is verified. The audibility of the observed frequency and amplitude modulation is discussed in terms of previously determined detection thresholds. The beating character of both frequency and amplitude modulations, however, distinguishes the phenomena from those previously studied and prompts further psychoacoustic investigations. It is shown that detuning of unison strings may significantly increase the frequency deviation of the frequency modulation in conjunction with affected amplitude modulation. The modulatory effects of coupling to adjacent tones therefore may possibly be utilized in the tuning process. A coupling of tones analogous to the situation in a piano may arise in other stringed musical instruments transferring string vibrations to a soundboard via a bridge.
Simultaneous measurement of acoustic and streaming velocities in a standing wave using laser Doppler anemometry
Authors: Thompson Michael W. , Atchley Anthony A.
Published: January 2006

Laser Doppler anemometry (LDA) with burst spectrum analysis (BSA) is used to study the acoustic streaming generated in a cylindrical standing-wave resonator filled with air. The air column is driven sinusoidally at a frequency of approximately 310 Hz and the resultant acoustic-velocity amplitudes are less than 1.3 m/s at the velocity antinodes. The axial component of fluid velocity is measured along the resonator axis, across the diameter, and as a function of acoustic amplitude. The velocity signals are postprocessed using the Fourier averaging method [Sonnenberger et al., Exp. Fluids 28, 217–224 (2000)]. Equations are derived for determining the uncertainties in the resultant Fourier coefficients. The time-averaged velocity-signal components are seen to be contaminated by significant errors due to the LDA/BSA system. In order to avoid these errors, the Lagrangian streaming velocities are determined using the time-harmonic signal components and the arrival times of the velocity samples. The observed Lagrangian streaming velocities are consistent with Rott’s theory [N. Rott, Z. Angew. Math. Phys. 25, 417–421 (1974)], indicating that the dependence of viscosity on temperature is important. The onset of streaming is observed to occur within approximately 5 s after switching on the acoustic field.
An artificial neural network approach for predicting architectural speech security (L)
Authors: Xu Jingfeng , Bradley John S. , Gover Bradford N.
Published: January 2006

Signal-to-noise type measures have been developed for predicting architectural speech privacy and speech security, which is required to accurately rate the probability of a listener outside a room being able to overhear conversations from within the room. However, these measures may not be ideal for speech security situations. In the present work, an approach that uses the artificial neural networks to directly represent the functional relationship between the octave band (250 Hz–8 kHz) S/N ratios and the speech intelligibility score and security thresholds has been investigated. The artificial neural network approach provides a direct and accurate method for predicting the speech intelligibility score and security thresholds.
Gas bubble and solid sphere motion in elastic media in response to acoustic radiation force
Authors: Ilinskii Yurii A. , Meegan G. Douglas , Zabolotskaya Evgenia A. , Emelianov Stanislav Y.
Published: January 2006

The general approach to estimate the displacement of rounded objects (specifically, gas bubbles and solid spheres) in elastic incompressible media in response to applied acoustic radiation force is presented. In this study, both static displacement and transient motion are analyzed using the linear approximation. To evaluate the static displacement of the spherical inclusion, equations coupling the applied force, displacement, and shear modulus of the elastic medium are derived. Analytical expressions to estimate the static displacement of solid spheres and gas bubbles are presented. Under a continuously applied static force, both the solid sphere and the initially spherical gas bubble are displaced, and the bubble is deformed. The transient responses of the inclusions are described using motion equations. The displacements of the inclusion in elastic incompressible lossless media are analyzed using both frequency-domain and time-domain formalism, and the equations of motion are derived for both a solid sphere and a gas bubble. For a short pulsed force, an analytical solution for the equations of motion is presented. Finally, transient displacement of the gas bubble in viscoelastic media is considered.
Analytical approach for sound attenuation in perforated dissipative silencers with inlet/outlet extensions
Authors: Selamet A. , Xu M. B. , Lee I.-J. , Huff N. T.
Published: January 2006

The acoustic attenuation performance of perforated dissipative circular expansion chambers with inlet/outlet extensions is investigated. The eigenvalues and eigenfunctions of the sound field are analytically determined in the extended inlet/outlet circular ducts, upstream/downstream end annular dissipative chambers, and the central perforated dissipative expansion chamber. Utilizing the continuity conditions of velocity/pressure at the interfaces, the transmission loss is predicted by a two-dimensional analytical approach. For a specific configuration, such predictions are compared with both experiments and a three-dimensional computational solution based on the substructure boundary element technique, showing a reasonable agreement. The analytical results for the effect of the absorbent resistivity, duct porosity, and geometry on the acoustic attenuation performance are discussed in detail.
Generation of longitudinal vibrations in piano strings: From physics to sound synthesis
Authors: Bank Balázs , Sujbert László
Published: January 2006

Longitudinal vibration of piano strings greatly contributes to the distinctive character of low piano notes. In this paper a simplified modal model is developed, which describes the generation of phantom partials and longitudinal free modes jointly. The model is based on the simplification that the coupling from the transverse vibration to the longitudinal polarization is unidirectional. The modal formulation makes it possible to predict the prominent components of longitudinal vibration as a function of transverse modal frequencies. This provides a qualitative insight into the generation of longitudinal vibration, while the model is still capable of explaining the empirical results of earlier works. The semi-quantitative agreement with measurement results implies that the main source of phantom partials is the transverse to longitudinal coupling, while the string termination and the longitudinal to transverse coupling have only small influence. The results suggest that the longitudinal component of the tone can be treated as a quasi-harmonic spectrum with formantlike peaks at the longitudinal modal frequencies. The model is further simplified and applied for the real-time synthesis of piano sound with convincing sonic results.
Acoustical measurement of the shear modulus for thin porous layers
Authors: Allard Jean F. , Henry Michel , Boeckx Laurens , Leclaire Philippe , Lauriks Walter
Published: January 2006

Simulations performed with the Biot theory show that for thin porous layers, a shear mode of the structure can be induced by a point-source in air located close to the layer. The simulations show that this mode is present around frequencies where the quarter wavelength of the shear Biot wave is equal to the thickness of the samples and show that it can be acoustically detected from the fast variations with frequency of the location of a pole of the reflection coefficient close to grazing incidence. The mode has been detected with this method for two reticulated plastic foams. For one of the foams studied, the velocity and the damping of the Rayleigh wave have been measured on a thicker layer of the same medium at higher frequencies, giving a real part of the shear modulus close to the one obtained from the measured location of the pole. The strong coupling of the shear mode with the acoustic field in air allows the measurement of the shear modulus without mechanical excitation.
Linear and nonlinear propagation of higher order modes in hard-walled circular ducts containing a real gas
Authors: Scheichl Stefan
Published: January 2006

This paper deals with the linear and nonlinear propagation of sound waves through a real gas contained in a circular tube with rigid, isothermal walls. Special emphasis is placed on the asymptotically correct treatment of the higher order modes and their interaction with the acoustic boundary layer. In the first part, a linear perturbation analysis is carried out to calculate the correction terms arising from the viscothermal damping mechanisms present in the system. In extension to previous work, the propagation length is assumed to be so large that the exponentially growing boundary layer effects do not only affect the second order terms of the sound pressure but also the leading order terms. The series expansions derived for the propagation parameters extend the results given in the literature with additional terms resulting from viscosity and heat conduction in the core region. The second part is concerned with the nonlinear modulation of a wave packet transmitted through a real gas. A damped nonlinear Schrödinger equation is derived and its solutions for positive as well as negative values of the nonlinearity parameter are studied. In particular, the case of wave propagation in ducts containing a so-called BZT fluid is discussed.
Bayesian sonar detection performance prediction in the presence of interference in uncertain environments
Authors: Sha Liewei , Nolte Loren W.
Published: January 2006

The detection performance of sonar systems can be greatly limited by the presence of interference and environmental uncertainty. The classic sonar equation does not take into account these two limiting factors and is inaccurate in predicting sonar detection performance. Here we have developed closed-form receiver operating characteristic (ROC) performance expressions for the Bayesian detector in the presence of interference in uncertain environments. Various scenarios extended from a NRL benchmark shallow-water model were used to test the analytical ROC expressions and to analyze the effects of interference and environmental uncertainty on detection performance. The results show that (1) the degradation on detection performance due to interference is greatly magnified by the presence of environmental uncertainty; (2) Bayesian sonar detection performance depends on the following fundamental parameters: the signal-to-noise ratio, the rank of the signal matrix, and the signal-to-interference coefficient; (3) the proposed analytical ROC performance predictions can be computed much faster than performance evaluations with commonly used Monte Carlo techniques.
On the stability of the effective apodization of the nonlinearly generated second harmonic with respect to range
Authors: Fedewa Russell J. , Wallace Kirk D. , Holland Mark R. , Jago James R. , Ng Gary C. , Robinson Brent S. , Rielly Matthew R. , Miller James G.
Published: January 2006

The concept of an effective apodization was introduced to describe the field pattern for the nonlinearly generated second harmonic (2f) within the focal zone using a linear propagation model. Our objective in this study was to investigate the validity of the concept of an effective apodization at 2f as an approach to approximating the field of the second harmonic over a wide range of depths. Two experimental setups were employed: a vascular imaging array with a water path and an adult cardiac imaging array with an attenuating liver path. In both cases the spatial dependencies of the ultrasonic fields were mapped by scanning a point-like hydrophone within a series of planes orthogonal to the propagation direction. The sampling distances were located before, within, and beyond the focal zone. The signals were Fourier transformed and the complex values at 2f were linearly backpropagated to the transmit plane in order to obtain an effective apodization. The measured results demonstrated a relatively constant effective apodization at 2f as a function of propagation distance. Finite amplitude computer simulations were found to be in agreement with these measurements. Thus the measure of the effective apodization at 2f provides an approximation to the second harmonic field outside the focal zone.