bluuebunny/crossref_metadata_2025 huggingface dataset:
On Baire-1/4 functions
Authors: Farmaki Vassiliki
Published: July 2002

We give descriptions of the spaces

D
(
K
)

D(K)

(i.e. the space of differences of bounded semicontinuous functions on

K
K

) and especially of

B

1

/

4

(
K
)

B_{1/4}(K)

(defined by Haydon, Odell and Rosenthal) as well as for the norms which are defined on them. For example, it is proved that a bounded function on a metric space

K
K

belongs to

B

1

/

4

(
K
)

B_{1/4}(K)

if and only if the

ω

t
h

\omega ^{ \mathrm {th}}

-oscillation,

o
s
c

ω

f

\mathrm {osc}_{\omega }f

, of

f
f

is bounded and in this case
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="double-vertical-bar f double-vertical-bar Subscript 1 slash 4 Baseline equals double-vertical-bar StartAbsoluteValue f EndAbsoluteValue plus ModifyingAbove normal o normal s normal c With tilde Subscript omega Baseline f double-vertical-bar Subscript normal infinity">

‖
f

‖

1

/

4

=
‖

|

f

|

+

o
s
c

~

ω

f

‖

∞

\| f\|_{1/4}=\|\, |f|+ \widetilde {\mathrm {osc}}_{\omega } f\|_{\infty }

. Also, we classify

B

1

/

4

(
K
)

B_{1/4}(K)

into a decreasing family

(

S

ξ

(
K
)

)

1
≤
ξ
>

ω
1

(S_{\xi }(K))_{1\leq \xi >\omega _1}

of Banach spaces whose intersection is equal to

D
(
K
)

D(K)

and

S
1

(
K
)
=

B

1

/

4

(
K
)

S_1 (K)=B_{1/4}(K)

. These spaces are characterized by spreading models of order

ξ
\xi

equivalent to the summing basis of

c
0

c_0

, and for every function

f
f

in

S

ξ

(
K
)

S_{\xi }(K)

it is valid that

o
s

ω

ξ

f

\mathrm {os}_{\omega ^{\xi }}f

is bounded. Finally, using the notion of null-coefficient of order

ξ
\xi

sequence, we characterize the Baire-1 functions not belonging to

S

ξ

(
K
)

S_{\xi }(K)

.
Existence and uniqueness for a degenerate parabolic equation with 𝐿¹-data
Authors: Andreu F. , Mazón J. , de León S. , Toledo J.
Published: July 2002

In this paper we study existence and uniqueness of solutions for the boundary-value problem, with initial datum in

L

1

(
Ω
)

L^{1}(\Omega )

,

u

t

=

d
i
v

a

(
x
,
D
u
)

in 
(
0
,
∞
)
×
Ω
,

\begin{equation*}u_{t} = \mathrm {div} \mathbf {a} (x,Du) \quad \text {in } (0, \infty ) \times \Omega , \end{equation*}

<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="minus StartFraction partial-differential u Over partial-differential eta Subscript a Baseline EndFraction element-of beta left-parenthesis u right-parenthesis on left-parenthesis 0 comma normal infinity right-parenthesis times partial-differential normal upper Omega comma">

−

∂
u

∂

η

a

∈
β
(
u
)

on 
(
0
,
∞
)
×
∂
Ω
,

\begin{equation*}-{\frac {{\partial u} }{{\partial \eta _{a}}}} \in \beta (u) \quad \text {on } (0, \infty ) \times \partial \Omega ,\end{equation*}

u
(
x
,
0
)
=

u

0

(
x
)

in 
Ω
,

\begin{equation*}u(x, 0) = u_{0}(x) \quad \text {in }\Omega ,\end{equation*}

where a is a Carathéodory function satisfying the classical Leray-Lions hypothesis,

∂

/

∂

η

a

\partial / {\partial \eta _{a}}

is the Neumann boundary operator associated to

a

\mathbf {a}

,

D
u

Du

the gradient of

u
u

and

β
\beta

is a maximal monotone graph in

R

×

R

{\mathbb {R}}\times {\mathbb {R}}

with

0
∈
β
(
0
)

0 \in \beta (0)

.
Monomial Bases for 𝐻*(𝐂𝐏^{∞}×𝐂𝐏^{∞}) over 𝒜(𝓅)
Authors: Crossley M.
Published: July 2002

We consider the polynomial algebra
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper H Superscript asterisk Baseline left-parenthesis bold upper C upper P Superscript normal infinity Baseline times bold upper C upper P Superscript normal infinity Baseline semicolon bold upper F Subscript p Baseline right-parenthesis">

H
∗

(

C

P
∞

×

C

P
∞

;

F

p

)

H^*(\mathbf {C} P^\infty \times \mathbf {C} P^\infty ; \mathbf {F}_p)

as a module over the mod

p
p

Steenrod algebra,

A

(
p
)

\mathcal {A}(p)

,

p
p

being an odd prime. We give a minimal set of generators consisting of monomials and characterise all such ‘monomial bases’.
On the contribution of the Coulomb singularity of arbitrary charge to the Dirac Hamiltonian
Authors: Xia Jingbo
Published: July 2002

We study the self-adjoint extensions of the Dirac operator

α
⋅
(
p
−
B
)
+

μ

0

β
−
W

\alpha \cdot (p - B) + \mu _{0}\beta - W

, where the electrical potential

W
W

contains a Coulomb singularity of arbitrary charge and the magnetic potential

B
B

is allowed to be unbounded at infinity. We show that if the Coulomb singularity has the form

v
(
r
)

/

r

v(r)/r

where

v
v

has a limit at 0, then, for any self-adjoint extension of the Dirac operator, removing the singularity results in a Hilbert-Schmidt perturbation of its resolvent.
The limit spaces of two-dimensional manifolds with uniformly bounded integral curvature
Authors: Shioya Takashi
Published: July 2002

We study the class of closed

2
2

-dimensional Riemannian manifolds with uniformly bounded diameter and total absolute curvature. Our first theorem states that this class of manifolds is precompact with respect to the Gromov-Hausdorff distance. Our goal in this paper is to completely characterize the topological structure of all the limit spaces of the class of manifolds, which are, in general, not topological manifolds and even may not be locally

2
2

-connected. We also study the limit of

2
2

-manifolds with

L
p

L^p

-curvature bound for

p
≥
1

p \ge 1

.
Classifying 2-groups by coclass
Authors: Newman M. , O’Brien E.
Published: July 2002

Now that the conjectures of Leedham-Green and Newman have been proved, we probe deeper into the classification of

p
p

-groups using coclass. We determine the pro-

2
2

-groups of coclass at most 3 and use these to classify the 2-groups of coclass at most 3 into families. Using extensive computational evidence, we make some detailed conjectures about the structure of these families. We also conjecture that the 2-groups of arbitrary fixed coclass exhibit similar behaviour.
FBI-1 Can Stimulate HIV-1 Tat Activity and Is Targeted to a Novel Subnuclear Domain that Includes the Tat-P-TEFb—containing Nuclear Speckles
Authors: Pendergrast P. Shannon , Wang Chen , Hernandez Nouria , Huang Sui
Published: July 2002

FBI-1 is a cellular POZ-domain–containing protein that binds to the HIV-1 LTR and associates with the HIV-1 transactivator protein Tat. Here we show that elevated levels of FBI-1 specifically stimulate Tat activity and that this effect is dependent on the same domain of FBI-1 that mediates Tat-FBI-1 association in vivo. FBI-1 also partially colocalizes with Tat and Tat's cellular cofactor, P-TEFb (Cdk9 and cyclin T1), at the splicing-factor–rich nuclear speckle domain. Further, a less-soluble population of FBI-1 distributes in a novel peripheral-speckle pattern of localization as well as in other nuclear regions. This distribution pattern is dependent on the FBI-1 DNA binding domain, on the presence of cellular DNA, and on active transcription. Taken together, these results suggest that FBI-1 is a cellular factor that preferentially associates with active chromatin and that can specifically stimulate Tat-activated HIV-1 transcription.
Irresistible IRES
Authors: Vagner Stéphan , Galy Bruno , Pyronnet Stéphane
Published: July 2002

Studies on the control of eukaryotic translation initiation by a cap‐independent recruitment of the 40S ribosomal subunit to internal messenger RNA sequences called internal ribosome entry sites (IRESs) have shown that these sequence elements are present in a growing list of viral and cellular RNAs. Here we discuss their prevalence, mechanisms whereby they may function and their uses in regulating gene expression.
Earlyin vitropriming of distinct Th cell subsets determines polarized growth of visceralizingLeishmaniain macrophages
Authors: Gomes Nitza A. , Barreto-de-Souza Victor , DosReis George A.
Published: July 2002

An in vitro priming system of murine naive splenocytes was established to investigate early immune responses to Leishmania chagasi, the agent of visceral leishmaniasis in the New World. Priming of splenocytes from resistant C3H and CBA or susceptible BALB and B10 mice with L. chagasi resulted in blast transformation and in proliferating parasite-specific CD4+ T cells secreting a differential complement of cytokines (IFN-γ and low IL-10 levels for resistant T cells; IFN-γ, IL-4 and high IL-10 levels for susceptible T cells). After priming, intracellular parasite load was much higher in susceptible than in resistant-type splenocyte cultures. On the other hand, infection of purified splenic macrophages from either resistant or susceptible mice with live L. chagasi promastigotes, resulted in comparable parasite loads. Moreover, when early CD4+ T cell priming in splenocyte cultures was disrupted with anti-CD4 mAb, polarized parasite growth was abolished, becoming comparable in resistant and susceptible cultures. Neutralizing IL-4 activity during splenocyte priming did not affect the final parasite load in susceptible cultures. However, neutralizing IL-10 activity markedly decreased parasite load in susceptible, but not in resistant splenic macrophages. These results suggest that IL-10 plays an important role in L. chagasi infection in susceptible hosts. The results also indicate that innate control of growth of a visceralizing Leishmania in splenic macrophages results from the ability to activate different CD4+ T cell subsets.
The effect of moxifloxacin on its target topoisomerases from Escherichia coli and Staphylococcus aureus
Authors: Schedletzky Holger , Wiedemann Bernd , Heisig Peter
Published: July 2002

The effect of moxifloxacin on its target enzymes was evaluated by three different approaches: (i) the MICs of moxifloxacin and nine other fluoroquinolones were determined for mutants of Escherichia coli (n = 13) and Staphylococcus aureus (n = 5) carrying different combinations of resistance mutations; (ii) the activity of moxifloxacin on isolated targets was determined as IC 50 values for wild-type and mutant type II topoisomerases from E. coli; and (iii) the mutation frequencies were determined for two single-step mutants (MI with a Ser83→Leu mutation in gyrA and WT-4 with a Ser80→Ile mutation in parC) and their parent strain (WT). Of the quinolones tested, moxifloxacin was the only one showing an equivalent high activity against both targets. This is reflected by a comparable high susceptibility of the test strains of E. coli and S. aureus and by the IC 50 values of moxifloxacin which were 50–90% lower than those of ciprofloxacin, norfloxacin and sparfloxacin for the wild-type and single mutant enzymes of gyrase and topoisomerase IV. However, double mutant GyrA was significantly more sensitive to moxifloxacin than to the other fluoroquinolones tested, while wild-type topoisomerase IV was two-fold more refractory. Mutation rates of WT, MI and WT-4 for ciprofloxacin and moxifloxacin were 5 × 10−8 vs 4 × 10−10, <6 × 10−11 vs <6 × 10−11; and 2 × 10 −6 vs 5 × 10−7, respectively. These data indicate an equivalenthigh inhibitory activity of moxifloxacin on DNA gyrase and topoisomerase IV of E. coli.
Biodistribution of adenoviral vector to nontarget tissues after local in vivo gene transfer to arterial wall using intravascular and periadventitial gene delivery methods
Authors: Hiltunen Mikko O. , Turunen Mikko P. , Turunen Anna‐Mari , Rissanen Tuomas T. , Laitinen Marja , Kosma Veli‐Matti , YlÄ‐Herttuala Seppo
Published: July 2002

Expression of transgene other than in the target tissue may cause side effects and safety problems in gene therapy. We analyzed biodistribution of transgene expression after intravascular and periadventitial gene delivery methods using the first generation nuclear‐targeted lacZ adenovirus. RT‐PCR and X‐Gal stainings were used to study transgene expression 14 days after the gene transfer. After intravascular catheter‐mediated gene transfer to rabbit aorta mimicking angioplasty procedure, the target vessel showed 1.1% ± 0.5 gene transfer efficiency. Other tissues showed varying lacZ gene expression indicating a systemic leakage of the vector with the highest transfection efficiency in hepatocytes (0.7% ± 0.5). X‐Gal staining of blood cells 24 h after the intravascular gene transfer indicated that a significant portion (1.8% ± 0.8) of circulating monocytes was transfected. X‐Gal‐positive cells were also found in testis. After periadventitial gene transfer using a closed silicon capsule placed around the artery, 0.1% ± 0.1 lacZ‐positive cells were detected in the artery wall. Positive cells were also found in the liver and testis (<0.01%), indicating that the virus escapes even from the periadventitial space, although less extensively than during the intravascular application. We conclude that catheter‐mediated intravascular and, to a lesser extent, periadventitial gene transfer lead to leakage of adenovirus to systemic circulation, followed by expression of the transgene in several tissues. Possible consequences of the ectopic expression of the transgene should be evaluated in gene therapy trials even if local gene delivery methods are used.—Hiltunen, M. O., Turunen, M. P., Turunen, A.‐M., Rissanen, T. T., Laitinen, M., Kosma, V.‐M., Ylä‐Herttuala, S. Biodistribution of adenoviral vector to nontarget tissues after local in vivo gene transfer to arterial wall using intravascular and periadventitial gene delivery methods. FASEB J. 14, 2230–2236 (2000)
The Croonian Lecture 1998. Identification of a protein kinase cascade of major importance in insulin signal transduction
Authors: Cohen Philip
Published: July 2002

Diabetes affects 3% of the European population and 140 million people worldwide, and is largely a disease of insulin resistance in which the tissues fail to respond to this hormone. This emphasizes the importance of understanding how insulin signals to the cell's interior. We have recently dissected a protein kinase cascade that is triggered by the formation of the insulin ‘second messenger’ phosphatidylinositide (3,4,5) trisphosphate (PtdIns(3,4,5)P3) and which appears to mediate many of the metabolic actions of this hormone. The first enzyme in the cascade is termed 3–phosphoinositide–dependent protein kinase–1 (PDK1), because it only activates protein kinase B (PKB), the next enzyme in the pathway, in the presence of PtdIns(3,4,5)P3. PKB then inactivates glycogen synthase kinase–3 (GSK3). PDK1, PKB and GSK3 regulate many physiological events by phosphorylating a variety of intracellular proteins. In addition, PKB plays an important role in mediating protection against apoptosis by survival factors, such as insulin–like growth factor–1.
In vivo nuclear magnetic resonance spectroscopy studies of the relationship between the glutamate--glutamine neurotransmitter cycle and functional neuroenergetics
Authors: Rothman Douglas L. , Sibson Nicola R. , Hyder Fahmeed , Shen Jun , Behar Kevin L. , Shulman Robert G.
Published: July 2002

In this article we review recent studies, primarily from our laboratory, using13C NMR (nuclear magnetic resonance) to non-invasively measure the rate of the glutamate-glutamine neurotransmitter cycle in the cortex of rats and humans. In the glutamate-glutamine cycle, glutamate released from nerve terminals is taken up by surrounding glial cells and returned to the nerve terminals as glutamine.13C NMR studies have shown that the rate of the glutamate-glutamine cycle is extremely high in both the rat and human cortex, and that it increases with brain activity in an approximately 1:1 molar ratio with oxidative glucose metabolism. The measured ratio, in combination with proposals based on isolated cell studies by P. J. Magistretti and co-workers, has led to the development of a model in which the majority of brain glucose oxidation is mechanistically coupled to the glutamate-glutamine cycle. This model provides the first testable mechanistic relationship between cortical glucose metabolism and a specific neuronal activity. We review here the experimental evidence for this model as well as implications for blood oxygenation level dependent magnetic resonance imaging and positron emission tomography functional imaging studies of brain function.
Axon damage and repair in multiple sclerosis
Authors: Perry V. Hugh , Anthony D. C.
Published: July 2002

It is well known that within long–standing multiple sclerosis (MS) lesions there is axonal loss but whether it is an early or late event has been more difficult to establish. The use of immunocytochemical methods that reveal axonal end–bulbs is a valuable approach to investigating acute axonal injury in human pathological material. The application of these techniques to multiple sclerosis tissue reveals evidence of axonal injury in acute lesions; the distribution of the end–bulbs in acute and active–chronic lesions is associated with regions of maximal density of infiltrating macrophages. Axon injury within the MS lesion will result in both Wallerian degeneration of the axon and also retrograde degeneration of the cell body. The functional consequences of the axon injury will depend upon numbers of axons injured and the topographical organization of the fibres coursing through the lesion. The molecular mechanisms by which the recruited leucocytes damage or transect the axons are not known. However, investigations in the
Wld
mutant mouse with very slow Wallerian degeneration demonstrate that axon degeneration is not simply a passive disintegration of the axon but has clear parallels with the active processes of programmed cell death. The presence of early axon injury and the consequences of an ever increasing load of neuronal damage has important implications not only for when therapy should be initiated in MS but also the therapeutic target.
Photorespiration: metabolic pathways and their role in stress protection
Authors: Wingler Astrid , Lea Peter J. , Quick W. Paul , Leegood Richard C.
Published: July 2002

Photorespiration results from the oxygenase reaction catalysed by ribulose–1,5–bisphosphate carboxylase/oxygenase. In this reaction glycollate–2–phosphate is produced and subsequently metabolized in the photorespiratory pathway to form the Calvin cycle intermediate glycerate–3–phosphate. During this metabolic process, CO
2
and NH
3
are produced and ATP and reducing equivalents are consumed, thus making photorespiration a wasteful process. However, precisely because of this inefficiency, photorespiration could serve as an energy sink preventing the overreduction of the photosynthetic electron transport chain and photoinhibition, especially under stress conditions that lead to reduced rates of photosynthetic CO
2
assimilation. Furthermore, photorespiration provides metabolites for other metabolic processes, e.g. glycine for the synthesis of glutathione, which is also involved in stress protection. In this review, we describe the use of photorespiratory mutants to study the control and regulation of photorespiratory pathways. In addition, we discuss the possible role of photorespiration under stress conditions, such as drought, high salt concentrations and high light intensities encountered by alpine plants.
Anisotropy of an high dose rate source measured with a miniature ionization chamber
Authors: Mishra Vivek , Waterman Frank M. , Suntharalingam Nagalingam
Published: July 2002

The anisotropy of a high dose rate (HDR) source was measured in air and in water using a miniature ionization chamber. Measurements were made at a distance of 5 cm from the source center at polar angles from 10°–170°. The anisotropy was found to be less pronounced in water, and the anisotropy is asymmetric about the transverse axis. The results agree with previous ionization chamber and TLD measurements to within Mean anisotropy factors were determined at each angle from all existing data at 5 cm distance, and compared to published Monte Carlo calculations, and to the values used in the microSelectron HDR brachytherapy planning system (BPS). The Monte Carlo photon transport code appears to systematically underestimate the anisotropy factor by up to 4% in the forward direction and overestimate it by up to 3% in the backward direction. The mean anisotropy factors also indicate that the BPS systematically underestimates the anisotropy factor by up to 3% in the forward direction, and overestimates it by up to 15% in the backward direction. However, the 15% difference occurs at 180° where it is not likely to be clinically significant.
Intravascular brachytherapy physics: Report of the AAPM Radiation Therapy Committee Task Group No. 60
Authors: Nath Ravinder , Amols Howard , Coffey Charles , Duggan Dennis , Jani Shirish , Li Zuofeng , Schell Michael , Soares Christopher , Whiting James , Cole Patricia E. , Crocker Ian , Schwartz Robert
Published: July 2002

Recent preclinical and clinical studies indicate that irradiation using ionizing radiation in the dose range of 15 to 30 Gy may reduce the occurrence of restenosis in patients who have undergone an angioplasty. Several delivery systems of intravascular brachytherapy have been developed to deliver radiation doses in this range with minimal normal tissue toxicity. In late 1995 the American Association of Physicists in Medicine (AAPM) formed a task group to investigate these issues and to report the current state of the art of intravascular brachytherapy physics. The report of this task group is presented here.
Conducting rod on the axis of a charged ring: The Kelvin water drop generator
Authors: Planinšič Gorazd , Prosen Tomaž
Published: July 2002

The problem of calculating the induced surface charge density along the finite length grounded conducting rod placed on the axis of the charged ring is solved numerically and compared with the experimental results. Two cases are considered in the theoretical treatment: the ring connected to a constant potential and the ring carrying a constant charge. The problem is related to the optimization of the Kelvin water drop electrostatic generator. A simple experiment is presented which gives reliable measurements of the induced charge density at the end of the conducting rod.
Visual introduction to Gaussian beams using a single lens as an interferometer
Authors: Peatross J. , Pack M. V.
Published: July 2002

Weak surface reflections from a simple lens can be used to observe interferences between collimated and focusing laser beams. The superimposed beams (one resulting from a double reflection within the lens) can be made to have similar intensities near the focus of the weaker beam by choosing the lens prescription and the divergence of the incident laser. An advantage to this inexpensive setup is its stability against vibrations. The relative phase between the two beams can be easily controlled through small adjustments to the lens alignment. Students using this setup with a CCD camera can explore the amplitude and phase properties of a Gaussian laser beam in the vicinity of the focus. This article also includes a brief review of Gaussian beams in the context of the Fresnel diffraction.
How do we know if we are doing a good job in physics teaching?
Authors: Ehrlich Robert
Published: July 2002

Whether it be at the level of the individual, the academic department, or the entire physics teaching profession, nearly all of us want to do a good job. But how can we know if we are succeeding? To what extent can we trust traditional measures of excellence in teaching, and what alternative measures resting on different—perhaps even unfashionable—assumptions might we consider?
Auditory backward recognition masking in children with a specific language impairment and children with a specific reading disability
Authors: McArthur G. M. , Hogben J. H.
Published: July 2002

The auditory backward recognition masking (ABRM) and intensity discrimination (ID) thresholds of children with a specific language impairment and poor reading (SLI-poor readers), children with an SLI and average reading (SLI-average readers), children with a specific reading disability and average spoken language skills (SRD-average language), and children with normal spoken and written language (controls) were estimated with “child-friendly” psychophysical tasks. The pattern of ABRM and ID scores suggests that a subset of children with concomitant oral language and reading impairments has poor ABRM thresholds, and that a subgroup of children with an SLI or SRD has poorer ID thresholds than controls. The latter result warns against using rapid auditory processing tasks that do not actively control for auditory discrimination ability. Further, some unusually poor ABRM scores and ID scores question the validity of extreme scores produced by children on psychophysical tasks. Finally, the poor oral language scores of many of the children who had impaired reading highlight the need to test the oral language skills of SRD samples to ascertain how homogeneous and specifically disabled they really are.
High-amplitude thermoacoustic effects in a single pore
Authors: Petculescu G. , Wilen L. A.
Published: July 2002

Nonlinear effects on thermoacoustic gain in a single pore are investigated experimentally. By creating a sharp temperature gradient in a uniform cross-section pore, the effect of high displacement amplitudes relative to the stack length is isolated from other high amplitude effects and also from effects due to geometrical discontinuities. The experiment probes displacement amplitudes which lie beyond the range of validity of the linear theory. The complex compressibility of nitrogen gas in the pore is measured for displacement amplitudes ranging from 2.5% to 60% of the stack length. No changes in the thermoacoustic response are observed over this range. Extending the upper limit to 175%, the power flow, as a function of the squared ratio of the displacement amplitude and the stack length, behaves linearly over the entire range.
Guided waves in a transversely isotropic cylinder immersed in a fluid
Authors: Ahmad Faiz
Published: July 2002

Propagation of flexural guided waves in a fluid-loaded transversely isotropic cylinder is studied. Numerical results are presented for a cobalt cylinder immersed in water. The phase velocities are not significantly affected except for several modes in which the energy leakage occurs into the fluid over certain frequency ranges. Attenuation spectra for the leaking modes are plotted.
Experimental and numerical investigations of resonant vibration characteristics for piezoceramic plates
Authors: Huang Chi-Hung , Ma Chien-Ching
Published: July 2002

Electronic speckle pattern interferometry (ESPI) is a full field, non-contact technique for measuring the surface displacement of a structure subjected to static loading or, especially, to dynamic vibration. In this article we employ an optical system called the amplitude-fluctuation ESPI with out-of-plane and in-plane measurements to investigate the vibration characteristics of piezoceramic plates. Two different configurations of piezoceramic plates, namely the rectangular and the circular plates, are discussed in detail. As compared with the film recording and optical reconstruction procedures used for holographic interferometry, the interferometric fringes of AF-ESPI are produced instantly by a video recording system. Because the clear fringe patterns will be shown only at resonant frequencies, both the resonant frequencies and the corresponding mode shapes are obtained experimentally at the same time by the proposed AF-ESPI method. Excellent quality of the interferometric fringe patterns for both the in-plane and out-of-plane vibration mode shapes is demonstrated. The resonant frequencies of the piezoceramic plates are also measured by the conventional impedance analysis. From experimental results, we find that the out-of-plane vibration modes (type A) with lower resonant frequencies cannot be measured by the impedance analysis and only the in-plane vibration modes (type B) will be shown. However, both the out-of-plane (bending) and in-plane (extensional) vibration modes of piezoceramic plates are obtained by the AF-ESPI method. Finally, the numerical finite element calculations are also performed, and the results are compared with the experimental measurements. It is shown that the numerical calculations and the experimental results agree fairly well for both the resonant frequencies and the mode shapes.
Effects of prosodic factors on spectral dynamics. II. Synthesis
Authors: Wouters Johan , Macon Michael W.
Published: July 2002

In Paper I [J. Wouters and M. Macon, J. Acoust. Soc. Am. 111, 417–427 (2002)], the effects of prosodic factors on the spectral rate of change of phoneme transitions were analyzed for a balanced speech corpus. The results showed that the spectral rate of change, defined as the root-mean-square of the first three formant slopes, increased with linguistic prominence, i.e., in stressed syllables, in accented words, in sentence-medial words, and in clearly articulated speech. In the present paper, an initial approach is described to integrate the results of Paper I in a concatenative synthesis framework. The target spectral rate of change of acoustic units is predicted based on the prosodic structure of utterances to be synthesized. Then, the spectral shape of the acoustic units is modified according to the predicted spectral rate of change. Experiments show that the proposed approach provides control over the degree of articulation of acoustic units, and improves the naturalness and intelligibility of concatenated speech in comparison to standard concatenation methods.
On the perceptual distance between speech segments
Authors: Ghitza Oded , Mohan Sondhi M.
Published: July 2002

For many tasks in speech signal processing it is of interest to develop an objective measure that correlates well with the perceptual distance between speech segments. (Speech segments are defined as pieces of a speech signal of duration 50–150 ms. For concreteness, a segment is considered to mean a diphone, i.e., a segment from the midpoint of one phoneme to the midpoint of the adjacent phoneme.) Such a distance metric would be useful for speech coding at low bit rates. Saving bits in those systems relies on a perceptual tolerance to acoustic perturbations from the original speech—perturbations whose effects typically last for several tens of milliseconds. Such a distance metric would also be useful for automatic speech recognition on the assumption that perceptual invariance to adverse signal conditions (e.g., noise, microphone, and channel distortions, room reverberation, etc.) and to phonemic variability (due to nonuniqueness of articulatory gestures) may provide a basis for robust performance. In this paper, attempts at defining such a metric will be described. The approach in addressing this question is twofold. First psychoacoustical experiments relevant to the perception of speech are conducted to measure the relative importance of various time-frequency “tiles” (one at a time) when all other time-frequency information is present. The psychophysical data are then used to derive rules for integrating the output of a model of auditory-nerve activity over time and frequency.
Further evidence that the sound-speed algorithm of Del Grosso is more accurate than that of Chen and Millero
Authors: Meinen Christopher S. , Watts D. Randolph
Published: July 2002

Estimates of the bottom depth of the ocean at 11 sites were determined by combining round-trip acoustic travel time measurements made by inverted echo sounders on the ocean bottom with sound-speed profiles determined from simultaneously measured temperature and salinity profiles. These depths were converted into pressures and were compared to independently measured bottom pressures to determine the accuracy of the algorithms used to calculate the sound-speed profile. The sound-speed algorithms tested were those derived by Del Grosso [J. Acoust. Soc. Am. 56, 1084–1091 (1974)] and by Chen and Millero [J. Acoust. Soc. Am. 62, 1129–1135 (1977)], as well as the corrected version of Chen and Millero’s algorithm recently published by Millero and Li [J. Acoust. Soc. Am. 95, 2757–2759 (1994)]. The results of this study agree with the results from recent acoustic tomography experiments which indicate that the algorithm of Del Grosso for the speed of sound in seawater is more accurate than the currently accepted standard algorithm of Chen and Millero. Del Grosso’s algorithm also produces more accurate results than those from the Millero and Li correction to the Chen and Millero algorithm.
Sensitivity of structural acoustic response to attachment feature scales
Authors: Shepard W. Steve , Cunefare Kenneth A.
Published: July 2002

When implementing a discrete computational method to predict the vibro-acoustic behavior of a larger structure one must decide how much effort and refinement to expend on modeling smaller attached structural components. In representing these attachments, or features, it is important to know what scales are important with regard to a valid prediction of the system response. To aid in the study of the impact of feature scales, sensitivity relationships for important system variables are developed in this paper. The sensitivity analysis will, for one, consider the change in the radiated power with respect to changes in the scale of an attached mass. These relations are developed analytically and do not require finite difference methods or eigenvalue derivatives. It is shown that computing the sensitivity of the radiated acoustic power only requires evaluating one additional term as all of the other terms are found during the normal course of modeling the system. Furthermore, the terms that include fluid-loading on the structure need only be reevaluated when the excitation frequency is changed. It is also noted that the sensitivity relations developed here can easily be used to investigate the effects of modifying a number of structural parameters.
An experimental evaluation of split-beam processing as a broadband bearing estimator for line array sonar systems
Authors: Stergiopoulos Stergios , Ashley Anthony T.
Published: July 2002

This paper examines the potential improvements in bearing estimation performance of split-beam processing over full-aperture beamforming for broadband signals. It presents theoretical results in order to define the details of the signal flow in a split-beam processor, and it provides theoretical performance predictions by using Cramer–Rao lower bound (CRLB) analysis. The split-beam processing scheme was implemented in a real-time line array system. Good agreement between the theoretical performance predictions and the associated experimental broadband results were obtained. The experimental results indicate that the advantage of improved bearing estimation performance of the split-beamformer over the conventional full-aperture beamformer may be practically insignificant for passive line array applications because of the split-beamformer’s poor performance in detecting very weak broadband signals.
Propagation of sound in a turbulent medium. I. Plane waves
Authors: Ostashev V. E. , Mellert Volker , Wandelt Ralf , Gerdes Frank
Published: July 2002

The paper presents formulas for the statistical moments of a plane sound wave propagating in moving random media (the turbulent atmosphere and ocean, turbulent flows of gases and fluids, etc.) with arbitrary spectra of temperature and medium velocity fluctuations. These statistical moments, which are most often of interest, are the following: the variances of log-amplitude and phase fluctuations, the correlation functions of log-amplitude and phase fluctuations, the mean sound field, the coherence function of a sound field, and the sound scattering cross section per unit volume. These statistical moments are calculated for Gaussian spectra of temperature and medium velocity fluctuations. It is shown that the contributions to the statistical moments due to sound scattering by medium velocity fluctuations may dramatically differ from those due to sound scattering by temperature fluctuations.
Comparison of two structural sensing approaches for active structural acoustic control
Authors: Maillard Julien P. , Fuller Chris R.
Published: July 2002

A numerical study comparing the use of two structural sensing approaches for sound radiation control is performed on a baffled rectangular plate. The first sensing approach implements an array of accelerometers whose outputs are filtered to construct an estimate of the sound pressure radiated at given angles in the far field. The second method uses the same array of point sensors to estimate the net volume acceleration of the plate. Results show the improved performances of the sensor observing far-field sound radiation over a volume acceleration based on sensor.
Sound radiation by various types of laboratory breaking waves in fresh and salt water
Authors: Kolaini Ali R.
Published: July 2002

A recent article [A. R. Kolaini and L. A. Crum, J. Acoust. Soc. Am. 96, 1755–1765 (1994)] reported the measurements of the ambient sound generated by laboratory breaking waves over the range 100–20 000 Hz in fresh water. Those observations from both spilling- and plunging-type breakers have been repeated in the same manner and wavemaker/anechoic tank with water that had 25‰ salt in its content. The observations in salt water, just like those in fresh water, reveal that the sources of sound in laboratory spilling breakers are due primarily to single bubble oscillations that can have frequencies lower than a few hundred Hertz. In the case of weak spilling breakers, the sound spectra level in fresh water was due primarily to single bubble oscillation, while the same breakers in salt water have introduced smaller size bubbles with large density. The relatively high-density populated bubble cloud generated by weak breakers shows the evidence of the onset of collective oscillation that was absent for the same breakers in the fresh water. In the case of moderate spilling and plunging breakers, it appears that both individual bubbles and bubble clouds can contribute to the acoustic emissions in fresh and salt water. The average sound spectra reveal that the peak frequencies of the spectra shift from a few kHz (weak, spilling breaker) to few hundred Hz (plunging breaker), and the high-frequency portions have slopes approximately 5–6 dB/oct, which are the slopes observed from the noise spectra of the ocean. Besides the high bubble density and smaller bubble sizes in salt water, all breakers experienced a significant increase in sound-pressure level in all observed frequency range. The ionic structure of the medium alters the sound radiation from bubbles. In this paper some of the observed acoustic signatures from breaking waves are discussed and a plausible explanation of how salt can effect the sound radiation from bubbles is given.
Underwater audiogram of a tucuxi (Sotalia fluviatilis guianensis)
Authors: Sauerland Matthias , Dehnhardt Guido
Published: July 2002

Using a go/no go response paradigm, a tucuxi (Sotalia fluviatilis guianensis) was trained to respond to pure-tone signals for an underwater hearing test. Auditory thresholds were obtained from 4 to 135 kHz. The audiogram curve shows that this Sotalia had an upper limit of hearing at 135 kHz; from 125 to 135 kHz sensitivity decreased by 475 dB/oct. This coincides with results from electrophysiological threshold measurements. The range of best hearing (defined as 10 dB from maximum sensitivity) was between 64 and 105 kHz. This range appears to be narrower and more restricted to higher frequencies in Sotalia fluviatilis guianensis than in other odontocete species that had been tested before. Peak frequencies of echolocation pulses reported from free-ranging Sotalia correspond with the range of most sensitive hearing of this test subject.
Generation and growth of bilayer defects induced by ultrasound
Authors: Malghani M. S. , Yang Jie , Wu Junru
Published: July 2002

Transdermal drug delivery is handicapped by the low skin permeability caused by highly ordered structure of lipid bilayers in the outer human skin layer. It has been reported that ultrasound can increase the permeability of human skin. The enhancement was attributed to acoustic cavitation but the underlying physical mechanism is not fully understood. As a model, dipalmitoylphosphatidylcholine (DPPC) lipid bilayers are insonicated by ultrasound of two submegahertz frequencies (168 kHz and 707 kHz). The free-field spatial peak pressure amplitudes of both are measured to be 6×105 Pa. Bilayer defects, which have average diameters of tens to hundreds of nanometers and can be detected by an atomic force microscope, are generated within less than 0.5 min. The number of the defects grows with time. The defect growth rate at the 168-kHz frequency is about 3.5 times that at the 707-kHz frequency.
Temperature measurements inside the oscillatory boundary layer produced by acoustic waves
Authors: Huelsz Guadalupe , Ramos Eduardo
Published: July 2002

In this work experimental techniques developed for acoustic temperature oscillation measurements in gases using a cold wire anemometer are reported. The techniques also proved accurate for measuring of the relative phase between temperature and pressure oscillations. Specifically, the structure of the oscillatory thermal boundary layer with isothermal conditions in the solid boundary of an acoustic standing wave in air with 130-Hz frequency and pressure oscillation amplitude up to 200 Pa is determined. Experimental results are satisfactorily compared to theoretical results of a linear theory.
A dynamic biomechanical model for neural control of speech production
Authors: Sanguineti Vittorio , Laboissière Rafael , Ostry David J.
Published: July 2002

A model of the midsagittal plane motion of the tongue, jaw, hyoid bone, and larynx is presented, based on the λ version of equilibrium point hypothesis. The model includes muscle properties and realistic geometrical arrangement of muscles, modeled neural inputs and reflexes, and dynamics of soft tissue and bony structures. The focus is on the organization of control signals underlying vocal tract motions and on the dynamic behavior of articulators. A number of muscle synergies or “basic motions” of the system are identified. In particular, it is shown that systematic sources of variation in an x-ray data base of midsagittal vocal tract motions can be accounted for, at the muscle level, with six independent commands, each corresponding to a direction of articulator motion. There are two commands for the jaw (corresponding to sagittal plane jaw rotation and jaw protrusion), one command controlling larynx height, and three commands for the tongue (corresponding to forward and backward motion of the tongue body, arching and flattening of the tongue dorsum, and motion of the tongue tip). It is suggested that all movements of the system can be approximated as linear combinations of such basic motions. In other words, individual movements and sequences of movements can be accounted for by a simple additive control model. The dynamics of individual commands are also assessed. It is shown that the dynamic effects are not neglectable in speechlike movements because of the different dynamic behaviors of soft and bony structures.
Acoustic bullets/transient Bessel beams: Near to far field transition via an impulse response approach
Authors: Stepanishen Peter R.
Published: July 2002

Acoustic transient Bessel beams (TBB) are a new class of waves which maintain their peak amplitude and general shape as they propagate in free space from an infinite planar aperture. The on axis and far field space-time properties of acoustic TBB waves generated by a finite spatial aperture are investigated using impulse response methods. The on-axis transition from the near field to the far field is investigated and several analogies to the acoustic field generated from a circular piston source are observed. In particular, the importance of an edge generated wave in determining the transition for the TBB field is clearly noted. Space-time properties of the far field are also investigated as a function of polar angle using impulse response methods. Numerical results are presented to illustrate the general characteristics of the on-axis and far field impulse response for a finite aperture.
Binaural signal detection with phase-shifted and time-delayed noise maskers
Authors: Breebaart Jeroen , van de Par Steven , Kohlrausch Armin
Published: July 2002

Detection thresholds were measured for interaurally in-phase sinusoids added to a narrow-band dichotic noise masker which was either interaurally phase shifted (NπSo condition) or time delayed (NτSo condition). The signals were spectrally centered in the noise bands and the delay τ equaled half the signal period. Both conditions were tested at 125 and 500 Hz for noise bandwidths of 10, 25, 50, and 100 Hz. In addition, NoSπ and NoSo thresholds were obtained. In contrast to expectations based on the EC theory, no differences in detection thresholds were observed between thresholds in phase-shifted and time-shifted maskers. The results also cannot be explained on the basis of more recent binaural models. The stimuli presented here might therefore serve as a useful validation tool in the development of new binaural theories and models.
Active attenuation of fan noise in an air-conditioning duct
Authors: Jiricek Ondrej , Konicek Petr
Published: July 2002

In this paper, the results of an investigation on using ANC systems in a duct will be presented. This system was used to reduce the noise of the axial-flow fan used as the noise source. The system was based on the adaptive digital signal processing controller. The attenuation of noise at low frequencies was achieved. This research represents a part of the project focused on the improvement of working conditions in operating theaters.
Types and frequencies of abnormal sound levels when using noise dosimeters to establish worker TWAs
Authors: Royster Larry H. , Royster Julia D.
Published: July 2002

The potential contamination of noise dosimetry noise exposure findings as impacted by the following types of artifacts was investigated: thumping of the microphone, moving the microphone around during the sample, hollering directly into the microphone, effects of body reflections, and blowing directly at the microphone. The findings from this investigation support the assumption that contamination of noise dosimetry daily noise exposure results is not of significant concern, at least when using a 5-dB exchange rate (OSHA). In addition, the detailed histogram records obtained from conducting noise dosimetry noise exposure surveys at five large industrial facilities were reviewed. Of the over 28 000 histogram samples reviewed, less than 14 samples indicated potential contamination from unusual noise sources. In summary, the results of this study confirm what the authors have observed over many years of conducting industrial noise exposure studies using noise dosimetry: contamination of noise dosimetry findings is not a significant issue (at least when a 5-dB exchange rate is utilized).
Species differences of distortion-product otoacoustic emissions: Comment on “Interpretation of distortion product otoacoustic emission measurements. I. Two stimulus tones” [J. Acoust. Soc. Am. 102, 413–429 (1997)]
Authors: Whitehead M. L.
Published: July 2002

In small mammals, there is convincing evidence for the existence of two discrete components of distortion-product otoacoustic emissions (DPOAEs), which have been called, variously, the active, low-level, or peak component, and the passive, high-level, or basal component. However, in humans, there is no convincing evidence for the existence of two analogous components of the DPOAE, at least for stimulus levels up to 85 dB SPL. These differences indicate that caution is required when generalizing from models of DPOAEs in small mammals to the human situation.