bluuebunny/crossref_metadata_2025 huggingface dataset:
Equal-likelihood decision making with limited information
Authors: Pitre Richard
Published: October 2005

Performance measures are examined for a detector-estimator based on an equal-likelihood signal probability model [N. R. Davis and R. Pitre, 978–992 and 993–1005 (1995)]. With limited integration time and SNR, detection and parameter estimation analysis based solely on estimation of cumulants is incomplete. Conventional performance measures like pfa and uncertainty measures such as cost uncertainty and decision information loss are examined as a function of integration time and estimation resolution. [Work sponsored by ONR(NRL).]
Modeling range-dependent propagation using trapped and leaky wedge modes
Authors: Fawcett John A. , Westwood Evan K. , Tindle Christopher T.
Published: October 2005

The use of coupled wedge modes in modeling range-dependent underwater acoustic propagation has been previously described by Primack and Gilbert [H. Primack and K. E. Gilbert, 3254–3262 (1991)]. Their approach has been extended by using leaky modes, in addition to the trapped ones, in wedge mode computations. Trapped modes decay exponentially in the basement and correspond, in terms of rays, to angles of propagation which are totally internally reflected above the basement interface; leaky modes are not well behaved in the basement, but provide an excellent discrete approximation to the continuous spectrum contribution in the water column. Because leaky modes are included in the computations, it is possible to model accurately shallow water environments where trapped/leaky mode conversions are important. Within a single wedge domain, adiabatic wedge mode theory is used for computations; at wedge junctures, a least-squares mode coupling scheme is employed. Numerical examples where the results of the coupled wedge mode method are compared to parabolic equation and standard adiabatic mode computations are presented.
Characterization of oceanographic/acoustic variability in littoral regions: Examples from two diverse test sites
Authors: Ali Hassan B.
Published: October 2005

As a result of complex oceanographic and atmospheric processes in littoral regions, environmental parameters are characterized by considerable spatial and temporal variability. The preceding imposes severe constraints on signal processing schemes, thereby adversely influencing systems based on acoustical, optical, magnetic, and oceanographic parameters. Acoustic signals are degraded by extensive interaction with the surface and bottom boundaries, the passage of internal waves, tidal changes, ambient noise, the influx of fresh water from rivers and marshes, etc. It is unlikely that these diverse phenomena will all be present in any single geographic area. Rather, the number and significance of the phenomena will vary from site to site. As a result, it is important to identify and characterize the germane ocean processes and environmental features at particular sites of interest, in order to isolate and assess their acoustic effects. The objectives of this task are to ascertain the minimum number of oceanographic parameters controlling the acoustic propagation, and their requisite spatial and temporal resolutions. The results of such investigations for two diverse sites off the U.S. and U.K. coasts are provided in this paper.
Cross-modal perception: Similarities and communalities
Authors: Marks Lawrence E.
Published: October 2005

Cross-modal perception encompasses two distinct domains. One domain consists of those objects, events, or environmental conditions (e.g., phonemes, shapes of objects, locations in space or time) about which different sensory modalities can provide common information; the other domain consists of dimensions or qualities of perceptual experience in different modalities that bear a perceptual similarity that itself need not reflect any communality in the environment (e.g., between greater auditory pitch and greater visual brightness). Cross-modal relations pervade perception, and they are readily determined through several psychophysical paradigms, including measures of perceptual equivalence between stimuli presented to different modalities (cross-modal matches); measures of cross-modal similarity, assessed by multidimensional scaling; and measures of cross-modal interactions in response speed and accuracy during stimulus classification. Although many cross-modal relations are grounded in perceptual similarities or environmental communalities, interactions in the processing of stimuli presented to different senses can readily be modulated by language, and can also depend on semantic recoding. [Work supported by NIH Grant DC00271.]
A wavelet auditory model and noise suppression
Authors: Teolis Anthony
Published: October 2005

Based on a wavelet auditory model (WAM) of the mammalian auditory system, discrete time-scale representations of acoustic signals which are inherently robust to ‘‘noise’’ emerge. The model consists of the two main processes of (i) a ‘‘continuous’’ wavelet transform with a causal analyzing wavelet determined by a ‘‘shark-fin’’-shaped frequency response (cochlear filter), and (ii) a specific and signal-dependent sampling of the wavelet transform. In general the pattern of samples in the wavelet domain is irregular and determined at lower frequencies by activity at higher frequencies. By analyzing the model in terms of the theory of mathematical frames, it is shown that acoustic signals may be fully recovered from their WAM representation through iterative reconstruction algorithms. Noise is thought of as that portion of an acoustic signal which is ‘‘incoherent’’ with respect to the underlying WAM frame functions. Because coherent energy is highly localized and incoherent (noise) energy is necessarily scattered in the time-scale plane by the WAM frame representation, wavelet shrinkage techniques provide powerful algorithms for noise suppression. Several numerical examples of the noise suppression abilities of these algorithms are presented in the paper.
A comparison of different aircraft noise metrics for large, medium, and small airports
Authors: Burn Melissa , Stusnick Eric , Ehrlich Gary
Published: October 2005

A wide variety of metrics are available to represent and evaluate noise impacts from aircraft operations. Two of these have gained wide acceptance and are used extensively in noise studies and mitigation programs throughout the United States: Day night average sound level (DNL) and sound exposure level (SEL). A third metric, time above (TA), is not often used but is very often requested by community members who believe it will represent their noise problem more convincingly than the others. Each metric differs significantly from the others both in the way it represents noise impact and in way the measure is best employed. For example, since DNL accounts for the loudness of individual events and the number of operations, an equivalent DNL value can result from a few very loud overflights or a large number of quieter ones. DNL is considered useful in predicting the average response of communities but not of individuals. The authors evaluated the noise impact for different sized airports (based on number of operations) by examining each of the three metrics DNL, SEL, and TA. The noise impacts are compared and the best use of the information is discussed.
Analysis and synthesis of speech
Authors: Tremain Tom
Published: October 2005

Speech produced by individual audience participants will be stored on a computer. Speech waveforms in the time and frequency domains will then be displayed by the computer. The speech will be played back in its natural form, and also after it has been analyzed and synthesized. Various transforms of the speech will be implemented and played back. For example, the speech will be speeded up and slowed down. The gender of the voice will be changed by altering the pitch periods. The speech will be made to seem as if the talker had a cold by changing the voicing of the consonant sounds.
The effects of incremental change in temporal envelope correlation on auditory fusion
Authors: Carter John R. , Rappold Patrick W. , Muelkar Madhuri S.
Published: October 2005

The effects of incremental change in degree of temporal envelope correlation on the auditory fusion of narrow-band noise (NBN) pairs was examined by placing fusion in competition with sequential streaming for one component of a NBN pair. Seven levels of envelope correlation were represented (r=1.0, 0.75, 0.50, 0.25, 0.00, −0.25, −0.35) by three sets of NBN pairs, for a total of 21 NBN pairs. A NBN pair consisted of a target-band spectrally centered at 2000 Hz, and a flanker-band centered at 1500 Hz. A NBN pair was played alternately with the target-band alone (captor-band) at an initial interstimulus-interval (ISI) of 500 ms. The ISI decreased automatically in 5- or 2-ms increments until a subject exited the program when judging the perceptual prominence of sequential streaming as greater than that of fusion. The ISI at exit was used to infer strength of fusion for the NBN pair. Shorter ISIs suggested stronger fusion; longer ISIs suggested weaker fusion. Results showed a trend for ISI to increase with a decrease in the degree of envelope correlation, which suggested a gradual decline in fusion strength as envelope correlation was incremented downward from perfect correlation.
Referential coding and the ‘‘severe departure’’ from Weber’s law
Authors: Plack Christopher J.
Published: October 2005

The Weber fraction for intensity discrimination for a 30-ms, 6.5-kHz sinusoidal pedestal is greater at medium pedestal levels that a low or high pedestal levels, particularly when the pedestal is gated with notched noise [R. P. Carlyon and B. C. J. Moore, 1369–1376 (1984)]. In the present experiments, Weber fractions were measured for a 30-ms, 6-kHz pedestal, at a range of levels between 40 and 70 dB SPL. Measurements were made in quiet and in the presence of a 110-ms notched noise with an onset 40 ms before the onset of the pedestal. The bandstop portion of the noise was 1-kHz wide, centered on 6 kHz, and the noise had a fixed spectrum level of 20 dB. In contrast to the earlier results, at pedestal levels of around 50 dB SPL the notched noise caused a reduction in the Weber fraction. It is suggested that the noise might improve performance by providing a proximal reference for coding the intensity of the pedestal. [Work supported by The Royal Society.]
Responses of dorsal cochlear nucleus single units to electrical pulse train stimulation of the auditory nerve with a cochlear implant electrode
Authors: O’Leary Stephen J. , Tong Yit C. , Clark Graeme M.
Published: October 2005

In response to 100-ms duration electrical stimulation within the range 50–400 pulses per second (pps), and at 1.6- to 2.4-mA stimulus current, a range of poststimulus time histogram (PSTH) patterns were observed from dorsal cochlear nucleus (DCN) units, they were usually primarylike, onset or ‘‘negative response’’ and occasionally buildup or pauser patterns. It appeared that the excitatory and suppressive processes, also termed neural drives, in response to 2.5-pps electrical stimulation were the main determinants of DCN unit responses to 50- to 400-pps stimulation. This was demonstrated by a model of DCN responses to electrical stimulation of the auditory nerve. The neural drives required to model the PSTH patterns were (i) an excitatory process with a latency of <5 ms, (ii) a second excitatory process latency of 4.5–10 ms, (iii) a long acting suppressive process with a latency of <15 ms and a duration of ≳70 ms, (iv) a short acting suppressive response with a latency of 2.5–3.7 ms and a duration usually <5 ms, but always <20, and (v) a drive contributing spontaneous activity to the unit. In addition to these processes which were observed at 2.5 pps, an additional, transient suppressive process was postulated to operate only at 50–400 pps. It was postulated that the PSTH patterns observed were due to differences in the strengths of these drives between units.
Metrics and standards for acoustic environmental assessments
Authors: Cavanagh Raymond C. , Hanna John S.
Published: October 2005

Because of stringent legal requirements and growing public interest, researchers must win government approval for any sea test involving acoustic emissions which could injure or harass marine animals. The approval process requires extensive documentation on the animals in the test area and likely impact of the test. This documentation (Environmental Assessment or Environmental Impact Statement) then includes predictions of shock wave and acoustic field characteristics in terms relevant to animal harassment and injury metrics. At present, there is no ‘‘standard’’ approach to developing an EA or an EIS; each research program provides its own format, metrics, etc. This presentation considers issues of standardization for the EA and EIS processes. In particular, literature on animal effects provides a variety of empirical thresholds in various units (e.g., peak pressure, impulse), while source metrics have their own particular units (e.g., energy density at range, intensity). Finally, signal must be estimated with a model that correctly propagates the quantity of interest in complex environments. None of these steps has a standard approach. Examples are given of problems encountered and recommendations made for standardization. Special attention is given to measurement techniques for marine animal response to sound.
Acoustic and perceptual investigation of breathy voice
Authors: Wayland Ratree , Gargash Scott , Longman Allard
Published: October 2005

Although breathy voice is typically characterized by an increase in spectral noise, it is notoriously difficult to devise a computational method to distinguish breathy from clear (modal) voice. The present study successfully makes use of an algorithm, originally developed to quantify aspects of pathological voice quality [G. de Krom, J. Speech Hear. Res. 36, 254–266 (1993)], which computes a harmonics-to-noise ratio (HNR). The algorithm calculates the harmonics-to-noise ratio using a comb filter defined in the cepstrum domain to separate the harmonics from the noise. Performance of the algorithm was tested on three speakers (2 male, 1 female) of Javanese producing a word list of 31 minimal breathy/clear word pairs. Results showed that the algorithm reliably distinguished breathy from clear tokens for all three speakers, with higher HNRs for clear than for breathy tokens. Moreover, accurate performance was obtained for nearly all frequency ranges investigated (60–2000 Hz, 2000–3000 Hz, 3000–5000 Hz). A comparison to other methods (such as H1–H2) will also be presented. Finally, perceptual rating experiments will be conducted to determine if the algorithm’s performance correlates with perceived degree of breathiness.
Comparison of impulse noise effects generated by two rifle muzzles
Authors: Pierson Linda L. , Price G. Richard , Kalb Joel T. , Mundis Pamela A.
Published: October 2005

The current impulse noise standard for US military uses a combination of peak sound pressure level and envelope duration to rate hearing hazard. There is general agreement that this procedure tends to overestimate the hazard from impulses that are broadly peaked at the low frequencies. One possible correction would be to frequency-weight the energy, giving less emphasis to the low frequencies. The current study, using the cat as a model, compares the physiological effect (auditory brainstem response threshold) of one rifle impulse generated either with the standard or an experimental muzzle device. The pressure from the standard muzzle device (N=9) (157.1 dB Peak, 9.62 ms B-duration, 0.9 J/M2) has a peak 13 dB ‘‘below’’ the pressure generated by the experimental muzzle device (N=10) (169.9 dB peak, 6.88 ms B-duration, 9 J/M2). It would be expected that the animals in the normal muzzle group would incur substantially less threshold shift than animals in the experimental muzzle group. However, group mean threshold were not significantly different. This finding challenges the current criterion. Furthermore, although both impulses contain essentially the same spectrum, because the energy composition of the impulses was very different, frequency weighting alone does not solve the problem.
Effects of acoustic cavitation on luminescent bacteria
Authors: Everbach E. Carr , Makin Inder R. S. , Vollmer Amy Cheng
Published: October 2005

The interaction of intense ultrasound with bacteria has implications for improving fundamental understanding in biology and bioacoustics, as well as providing possible applications in water purification and medicine. An investigation will be presented of the effects of acoustic cavitation on E.coli bacteria that have been genetically engineered to emit visible light when subjected to physical or chemical stress. Genetic cloning techniques allow the placement of the lux gene, derived from luminescent marine microorganisms, at specific locations in bacterial DNA. Each placement location yields light production in proportion to the repair mechanism employed by the bacteria in response to specific kinds of stress (oxidative damage, DNA damage, membrane damage, protein damage, thermal damage, etc.). A 20-MHz passive acoustic detector [abstract, Huertas etal., 2856 (1994)] was used to quantify cavitational activity when bacteria were exposed to 1-MHz pulsed ultrasound. By comparing a measure of cavitational activity with light output from exposed bacteria that were presensitized to different kinds of damage, cavitational effects on both bacteria and mammalian cells can be better understood.
Effects of bottom type variability on modeled backscattered levels of a high-frequency sonar
Authors: Savage Kristen D. , Meredith Roger W.
Published: October 2005

Results investigating the effects of variable bottom composition on modeled high-frequency backscattered levels are presented for a typical shallow water, range-dependent environment. The modeled environment consisted of a single sound-speed profile, a flat sea bottom with range-dependent bottom composition, and a benign sea surface. Coarse and fine grain sandy areas were partitioned in range to create range dependence. Bottom backscattering and reflection loss for each partition were obtained from the recent University of Texas high-frequency ocean bottom backscatter model [N. P. Chotiros and F. A. Boyle, 3264(A) (1994)]. Differences of 5 dB were discernible between the fine–coarse–fine sand bottom and a range-independent fine sand bottom for ranges <500 m. The trend and structure of the backscattered levels were nearly identical for both bottom types. Differences of 42 dB for ranges <500 m were visible in the modeled backscattered level of the fine–coarse–fine sand bottom and the coarse–fine–coarse sand bottom. The trend and structure of the backscattered levels were also different. In all cases, surface reverberation had a strong impact on the backscattered levels, trends, and structures. [Work supported by MCM Tactical Environmental Data Systems (MTEDS) under Program Element 62435N.]
Method of prognostic noise and vibration from industrial setups
Authors: Ekimov Alexander E. , Tyutin Vladimir A. , Dudnik Rostislav A. , Kolpakov Andrei B.
Published: October 2005

This paper considers a method to determine the contribution of vibroactive industrial setups (prior to their mounting on the basement) to outside noises and vibrations. The technique offered is based on the experimental determination of transfer coefficients of noises and vibrations from outside sources (acoustic generators and vibrators) into environmental points of interest. The contribution of a setup is determined by multiplying vibration and noise characteristics (measured using an operating analogue setup) and experimentally measured transfer coefficients mentioned above. The technique was used to estimate the levels of vibrations and air noises at the shop of microelectronics at the Communication Equipment Plant in Nizhny Novgorod. The vibrations and noises in question were caused by an electrocompressor located in a separate building near the shop. A vibrator generating a force from 500 to 6000 N in the frequency range 20–60 Hz was used to determine vibration transfer coefficients. The experimental estimations showed that electrocompressor noises and vibrations will not affect the operation of precision devices in the shop. The prognosis was fully verified by measurements taken after electrocompressor mounting and the noises and vibrations did not exceed background ones.
Comparison of exact and approximate solutions of multiple scattering between interfaces in rough waveguides
Authors: LePage Kevin D.
Published: October 2005

Modeling propagation in rough waveguides introduces the interesting question of how to treat multiply scattered waves. One approach is to treat the rough surface scattering at the waveguide boundaries under an extended Born approximation [W. Kuperman and H. Schmidt, J. Acoust. Soc. Am. 86 (1989)]. Under this approach multiple scatter effects are incorporated into the mean field through a second-order correction in surface roughness, and the scattering amplitudes at each interface are assumed to be driven by the corrected mean field alone. Coupled integral equations which the total field in a rough waveguide must satisfy at the source depth are available in the literature [D. Berman, J. Acoust. Soc. Am. 92 (1992)], making it possible to evaluate the approximate results in a consistent way. Here the results obtained by solving the integral equations are compared to those obtained by adding the scattered field to either a corrected or an uncorrected mean field. Conclusions regarding the bounding behavior of the approximate solutions are drawn for various roughness and waveguide parameters in the low frequency regime.
Reflection and refraction of longitudinal wave at an interface between two micropolar elastic solids in welded contact
Authors: Tomar S. K. , Gogna M. L.
Published: October 2005

The problem of reflection and refraction of a longitudinal wave at an interface between two micropolar elastic solids is discussed. Amplitude ratios and energy ratios for various reflected and refracted waves have been obtained for a longitudinal wave impinging obliquely at a plane discontinuity of two linear micropolar elastic solids in welded contact. Numerical values of the amplitude ratios and energy ratios have been computed as a function of angle of emergence of the wave, for a specific model, and these have also been plotted graphically. Amplitude ratios as a function of frequency have also been computed and exhibited graphically. The results of Parfitt and Eringen [J. Acoust. Soc. Am. 45, 1258–1272 (1969)] have been derived as a special case. Some other special cases are discussed.
Finite amplitude standing waves in metallic rods
Authors: Campos-Pozuelo C. , Gallego-Juárez J. A.
Published: October 2005

Large-amplitude extensional standing waves in metals are studied theoretically and experimentally. Starting from the nonlinear elastodynamic equation for perfectly elastic solids, a one-dimensional second-order model is formulated for resonant rods. Losses are neglected and superposition of forward and backward waves is assumed. Spatial distributions of the force and particle velocity are obtained theoretically as well as the waveforms. The experimental work consists of measuring and analyzing the vibration signal along the length of cylindrical rod samples of a titanium alloy at constant temperature. Stepped rod samples are used to achieve higher strain amplitudes. The samples are driven by means of a piezoelectric transducer. The vibration amplitudes and waveforms are monitored by using a nonintrusive laser vibrometer. From a comparison between the experimental and theoretical results a value for the nonlinearity parameter of the titanium alloy is derived.
Performance evaluation of optimized diffusors
Authors: D’Antonio Peter
Published: October 2005

Theoretical boundary element calculations verified that the 2-D Hankel function is a useful and fast approximation for predicting scattering from one-dimensional extruded shapes. Experimental polar response measurements on 1:5 scale models of QRDs and optimized stepped diffusors proposed by Cox [J. Acoust. Soc. Am. 97, 2928–2936 (1995)] verified the increased diffusivity of the stepped diffusors within the frequency range optimized and for the angle of incidence and observer distance used. However, outside this range and at 30° and 60° angles of incidence, the diffusion response for one and two periods of the stepped diffusor is not optimized. Analysis of a faceted half-cylinder, with better diffusivity than the stepped diffusor, reveals the sensitivity and possible limits of the minimization process. Over a broad bandwidth the response for the QRD is better than that of the stepped diffusor at non-normal angles of incidence.
The evolving Internet
Authors: Parseghian Pat
Published: October 2005

The World Wide Web and point-and-click browsers have revolutionized the way one looks at the Internet. The Internet is not just for computer scientists anymore—it links elementary schools, businesses, and homes around the globe. Addresses for resources on the World Wide Web appear in national magazines, local newspapers, and are televised on the evening news. Following a brief overview of the Internet and traditional text-based Internet services, this presentation will focus on emerging multimedia uses of the Internet. Multimedia extensions for electronic mail allow us to share images and sounds. The MBone (Multicast Backbone) supports collaborative tools for audio and video conferencing, as well as a shared whiteboard. On the World Wide Web, one can look at the weather report, read colleagues’ technical papers, go shopping, and check the traffic conditions, all before leaving home for the office! While the Internet is straining to accommodate its escalating load, advances in networking technology promise a bright future.
The Mid-Pleistocene Transition in the Tropical Pacific
Authors: Medina-Elizalde Martín , Lea David W.
Published: October 2005

A sea surface temperature (SST) record based on planktonic foraminiferal magnesium/calcium ratios from a site in the western equatorial Pacific warm pool reveals that glacial-interglacial oscillations in SST shifted from a period of 41,000 to 100,000 years at the mid-Pleistocene transition, 950,000 years before the present. SST changes at both periodicities were synchronous with eastern Pacific cold-tongue SSTs but preceded changes in continental ice volume. The timing and nature of tropical Pacific SST changes over the mid-Pleistocene transition implicate a shift in the periodicity of radiative forcing by atmospheric carbon dioxide as the cause of the switch in climate periodicities at this time.
Analysis of a Highly Flexible Conformational Immunogenic Domain A in Hepatitis C Virus E2
Authors: Keck Zhen-Yong , Li Ta-Kai , Xia Jinming , Bartosch Birke , Cosset François-Loïc , Dubuisson Jean , Foung Steven K. H.
Published: October 2005

Hepatitis C (HCV) E2 glycoprotein is involved in virus attachment and entry, and its structural organization is largely unknown. Characterization of a panel of human monoclonal antibodies (HMAbs) to HCV by competition studies has led to an immunogenic organization model of E2 with three domains designated A, B, and C and epitopes in each domain having similar structural and functional properties. Domain A contains nonneutralizing epitopes, and domains B and C contain neutralizing epitopes. The isolation and characterization of three new HMAbs within domain A for a total of six provide support for this model. All six domain A HMAbs do not neutralize HCV retroviral pseudotype particle (HCVpp) infection on Huh-7 cells, and all six HMAbs have similar binding affinity and maximum binding,
B
max
, a relative indicator of epitope density, as other neutralizing HMAbs, suggesting that neutralization is epitope specific and not by binding to any surface epitope. The dose-dependent neutralizing activity of CBH-7, an HMAb to a domain C epitope in spatial proximity to domain A, and of CBH-5, a domain B HMAb to a more distant epitope, were tested in the presence and absence of each domain A HMAb. No enhancement or reduction in CBH-7 or CBH-5 neutralizing activity was observed, indicating that the potential induction of nonneutralizing antibodies should not be a central issue for HCV vaccine design. To assess whether domain A is involved in the structural changes as part of a pH-dependent virus envelope fusion process, changes in antibody binding patterns to normal pH and acid pH-treated HCVpp were measured. Antibody binding affinity of HMAbs to HCVpp was not affected by low pH. However, the
B
max
values for low-pH-treated HCVpp with antibodies to domain A increased 46%, for domain C (CBH-7) they increased 23%, and for domain B (CBH-5) there was a decrease of 12%. Collectively, the organization and function of HCV E2 antigenic domains are roughly analogous to the large envelope glycoprotein E organizational structure for other flaviviruses with three distinct structural and functional domains.
Worldwide Genomic Diversity of the High-Risk Human Papillomavirus Types 31, 35, 52, and 58, Four Close Relatives of Human Papillomavirus Type 16
Authors: Calleja-Macias Itzel E. , Villa Luisa L. , Prado Jose C. , Kalantari Mina , Allan Bruce , Williamson Anna-Lise , Chung Lap-Ping , Collins Robert J. , Zuna Rosemary E. , Dunn S. Terence , Chu Tang-Yuan , Cubie Heather A. , Cuschieri Kate , von Knebel-Doeberitz Magnus , Martins Claudia R. , Sanchez Gloria I. , Bosch F. Xavier , Munoz Nubia , Bernard Hans-Ulrich
Published: October 2005

Among the more than one hundred formally described human papillomavirus (HPV) types, 18 are referred to as high-risk HPV types due to their association with anogenital cancer. Despite pathogenic similarities, these types form three remotely related taxonomic groups. One of these groups is called HPV species 9 and is formed by HPV-16, the most common and best-studied type, together with HPV-31, -33, -35, -52, -58, and -67. Previous worldwide comparisons of HPV-16 samples showed about 2% nucleotide diversity between isolates, which were subsequently termed variants. The distribution of divergent variants has been found to correlate frequently with the geographic origin and the ethnicity of the infected patients and led to the concept of unique African, European, Asian, and Native American HPV-16 variants. In the current study, we address the question of whether geography and ethnicity also correlate with sequence variations found for HPV-31, -35, -52, and -58. This was done by sequencing the long control region in samples derived from Europe, Asia, and Africa, and from immigrant populations in North and South America. We observed maximal divergence between any two variants within each of these four HPV types ranging from 1.8 to 3.6% based on nucleotide exchanges and, occasionally, on insertions and deletions. Similar to the case with HPV-16, these mutations are not random but indicate a relationship between the variants in form of phylogenetic trees. An interesting example is presented by a 16-bp insert in select variants of HPV-35, which appears to have given rise to additional variants by nucleotide exchanges within the insert. All trees showed distinct phylogenetic topologies, ranging from dichotomic branching in the case of HPV-31 to star phylogenies of the other three types. No clear similarities between these types or between these types and HPV-16 exist. While variant branches in some types were specific for Europe, Africa, or East Asia, none of the four trees reflected human evolution and spread to the extent illustrated by HPV-16. One possible explanation is that the rare HPV types that we studied spread and thereby diversified more slowly than the more abundant HPV-16 and may have established much of today's variant diversity already before the worldwide spread of humans 100,000 years ago. Most variants had prototypic amino acid sequences within the E6 oncoprotein and a segment of the L1 capsid protein. Some had one, two, or three amino acid substitutions in these regions, which might indicate biological and pathogenic diversity between the variants of each HPV type.
AFFINE CURVATURE HOMOGENEOUS 3-DIMENSIONAL LORENTZ MANIFOLDS
Authors: GILKEY P. , NIKČEVIĆ S.
Published: October 2005

We study a family of 3-dimensional Lorentz manifolds. Some members of the family are 0-curvature homogeneous, 1-affine curvature homogeneous, but not 1-curvature homogeneous. Some are 1-curvature homogeneous but not 2-curvature homogeneous. All are 0-modeled on indecomposible local symmetric spaces. Some of the members of the family are geodesically complete, others are not. All have vanishing scalar invariants.
COMPLETE COVERINGS AND GALOIS CORINGS
Authors: BRZEZIŃSKI TOMASZ , WRIGHTSON ADAM P.
Published: October 2005

It is shown that any finite complete covering of a non-commutative algebra in the sense of Calow and Matthes [16] gives rise to a Galois coring.
CLASSICAL AND QUANTUM FERMIONS LINKED BY AN ALGEBRAIC DEFORMATION
Authors: MOSTAFAZADEH ALI
Published: October 2005

We study the regular representation ρζ of the single-fermion algebra [Formula: see text], i.e., c2 = c+2 = 0, cc+ + c+c = ζ1, for ζ ∈ [0,1]. We show that ρ0 is a four-dimensional nonunitary representation of [Formula: see text] which is faithfully irreducible (it does not admit a proper faithful subrepresentation). Moreover, ρ0 is the minimal faithfully irreducible representation of [Formula: see text] in the sense that every faithful representation of [Formula: see text] has a subrepresentation that is equivalent to ρ0. We therefore identify a classical fermion with ρ0 and view its quantization as the deformation: ζ : 0 → 1 of ρζ. The latter has the effect of mapping ρ0 into the four-dimensional, unitary, (faithfully) reducible representation ρ1 of [Formula: see text] that is reminiscent of a Dirac fermion.
LINKS BETWEEN CONNECTIONS, PARALLEL TRANSPORTS AND TRANSPORTS ALONG PATHS IN DIFFERENTIABLE FIBER BUNDLES
Authors: ILIEV BOZHIDAR Z.
Published: October 2005

The axiomatic approach to parallel transport theory is partially discussed. Bijective correspondences between the sets of connections, (axiomatically defined) parallel transports and transports along paths that satisfy some additional conditions are constructed. In particular, the equivalence between the concepts "connection" and "(axiomatically defined) parallel transport" is established.
NOETHER IDENTITIES OF A DIFFERENTIAL OPERATOR: THE KOSZUL–TATE COMPLEX
Authors: SARDANASHVILY G.
Published: October 2005

Given a generic Lagrangian system, its Euler–Lagrange operator obeys Noether identities which need not be independent, but satisfy first-stage Noether identities, and so on. This construction is generalized to arbitrary differential operators on a smooth fiber bundle. Namely, if a certain necessary and sufficient condition holds, one can associate to a differential operator the exact chain complex with the boundary operator whose nilpotency restarts all the Noether identities characterizing the degeneracy of an original differential operator.
LAGRANGIAN AND HAMILTONIAN FORMULATION OF SPHERICAL SHELL DYNAMICS
Authors: KIJOWSKI J. , MAGLI G. , MALAFARINA D.
Published: October 2005

Lagrangian and Hamiltonian descriptions of the dynamics of a self-gravitating matter shell in General Relativity are discussed in general. The case of a spherical shell composed of an elastic fluid is then considered, its Lagrangian function is derived from first principles and the Hamiltonian is calculated. Known results for dust shells are recovered as particular cases.
ALTERNATIVE ALGEBRAIC STRUCTURES FROM BI-HAMILTONIAN QUANTUM SYSTEMS
Authors: MARMO G. , SCOLARICI G. , SIMONI A. , VENTRIGLIA F.
Published: October 2005

We discuss the alternative algebraic structures on the manifold of quantum states arising from the alternative Hermitian structures associated with the quantum bi-Hamiltonian systems. We also consider the consequences at the level of the Heisenberg picture in terms of the deformations of the associative product on the space of observables.
QUANTUM BUNDLES AND QUANTUM INTERACTIONS
Authors: CANARUTTO DANIEL
Published: October 2005

A geometric framework for describing quantum particles on a possibly curved background is proposed. Natural constructions on certain distributional bundles ("quantum bundles") over the space–time manifold yield a quantum "formalism" along any 1-dimensional timelike submanifold (a "detector"); in the flat, inertial case this reproduces the basic results of the usual quantum field theory, while in general it could be seen as a local, "linearized" description of the actual physics.
On the role and fate of LPS-dephosphorylating activity in the rat liver
Authors: Tuin Annemarie , Huizinga-Van der Vlag Ali , van Loenen-Weemaes Anne-Miek M. A. , Meijer Dirk K. F. , Poelstra Klaas
Published: October 2005

Gut-derived lipopolysaccharide (LPS) plays a role in the pathogenesis of liver diseases like fibrosis. The enzyme alkaline phosphatase (AP) is present in, among others, the intestinal wall and liver and has been previously shown to dephosphorylate LPS. Therefore, we investigated the effect of LPS on hepatic AP expression and the effect of AP on LPS-induced hepatocyte responses. LPS-dephosphorylating activity was expressed at the hepatocyte canalicular membrane in normal and fibrotic animals. In addition to this, fibrotic animals also displayed high LPS-dephosphorylating activity around bile ducts. The enzyme was shown to dephosphorylate LPS from several bacterial species. LPS itself rapidly enhanced the intrahepatic mRNA levels for this enzyme within 2 h by a factor of seven. Furthermore, in vitro and in vivo studies showed that exogenous intestinal AP quickly bound to the asialoglycoprotein receptor on hepatocytes. This intestinal isoform significantly attenuated LPS-induced hepatic tumor necrosis factor-α and nitric oxide (nitrite and nitrate) responses in vitro. The enzyme also reduced LPS-induced hepatic glycogenolysis in vivo. This study shows that LPS enhances AP expression in hepatocytes and that intestinal AP is rapidly taken up by these same cells, leading to an attenuation of LPS-induced responses in vivo. Gut-derived LPS-dephosphorylating activity or enzyme upregulation within hepatocytes by LPS may therefore be a protective mechanism within the liver.
Regional ventricular wall thickening reflects changes in cardiac fiber and sheet structure during contraction: quantification with diffusion tensor MRI
Authors: Chen Junjie , Liu Wei , Zhang Huiying , Lacy Liz , Yang Xiaoxia , Song Sheng-Kwei , Wickline Samuel A. , Yu Xin
Published: October 2005

Dynamic changes of myocardial fiber and sheet structure are key determinants of regional ventricular function. However, quantitative characterization of the contraction-related changes in fiber and sheet structure has not been reported. The objective of this study was to quantify cardiac fiber and sheet structure at selected phases of the cardiac cycle. Diffusion tensor MRI was performed on isolated, perfused Sprague-Dawley rat hearts arrested or fixed in three states as follows: 1) potassium arrested (PA), which represents end diastole; 2) barium-induced contracture with volume (BV+), which represents isovolumic contraction or early systole; and 3) barium-induced contracture without volume (BV−), which represents end systole. Myocardial fiber orientations at the base, midventricle, and apex were determined from the primary eigenvectors of the diffusion tensor. Sheet structure was determined from the secondary and tertiary eigenvectors at the same locations. We observed that the transmural distribution of the myofiber helix angle remained unchanged as contraction proceeded from PA to BV+, but endocardial and epicardial fibers became more longitudinally orientated in the BV− group. Although sheet structure exhibited significant regional variations, changes in sheet structure during myocardial contraction were relatively uniform across regions. The magnitude of the sheet angle, which is an index of local sheet slope, decreased by 23 and 44% in BV+ and BV− groups, respectively, which suggests more radial orientation of the sheet. In summary, we have shown for the first time that geometric changes in both sheet and fiber orientation provide a substantial mechanism for radial wall thickening independent of active components due to myofiber shortening. Our results provide direct evidence that sheet reorientation is a primary determinant of myocardial wall thickening.
Peroxynitrite hyperpolarizes smooth muscle and relaxes internal carotid artery in rabbit via ATP-sensitive K+ channels
Authors: Ohashi Masuo , Faraci Frank , Heistad Donald
Published: October 2005

The goal of this study was to determine the effects of peroxynitrite (ONOO−) on smooth muscle membrane potential and vasomotor function in rabbit carotid arteries. ONOO− is known to affect vascular tone by several mechanisms, including effects on K+ channels. Xanthine (X, 0.1 mM), xanthine oxidase (XO, 0.01 U/ml), and a low concentration of sodium nitroprusside (SNP, 10 nM) were used to generate ONOO−. In the common carotid artery, X and XO (X/XO) in the presence of SNP tended to increase tension. In contrast, in the internal carotid artery, X/XO in the presence of SNP transiently hyperpolarized the membrane (−8.5 ± 1.8 mV, mean ± SE) and decreased tension (by 85 ± 5.6%). In internal carotid arteries, in the absence of SNP, X/XO did not hyperpolarize the membrane and produced much less relaxation (by 23 ± 5.6%) than X/XO and SNP. Ebselen (50 μM) inhibited both hyperpolarization and relaxation to X/XO and SNP, and uric acid (100 μM) inhibited relaxation. Glibenclamide (1 μM) abolished hyperpolarization and inhibited relaxation during X/XO and SNP. Charybdotoxin (100 nM) or tetraethylammonium (1 mM) did not affect hyperpolarization or relaxation, respectively. These results suggest that ONOO− hyperpolarizes and relaxes smooth muscle in rabbit internal carotid artery but not in common carotid artery through activation of KATP channels.
Digitalis: new actions for an old drug
Authors: Wasserstrom J. Andrew , Aistrup Gary L.
Published: October 2005

The mechanisms by which digitalis causes its therapeutic and toxic actions have been studied for nearly a half century, revealing a great deal about cardiac cell regulation of intracellular ions via the Na-K-ATPase (NKA) and how it is altered by cardiac glycosides. However, recent observations suggest that digitalis may have additional effects on cardiac cell function in both the short and long term that include intracellular effects, interactions with specific NKA isoforms in different cellular locations, effects on intracellular (including nuclear) signaling, and long-term regulation of intracellular ionic balances through circulating ouabain-like compounds. The purpose of this review is to examine the current status of a number of the newest and most interesting developments in the study of digitalis with a particular focus on cardiac function, although we will also discuss some of the new advances in other relevant cardiovascular effects. This new information has important implications for both our understanding of ionic regulation in normal and diseased hearts as well as for potential avenues for the development of future therapeutic interventions for the treatment of heart failure.
Intron 1 sequences are required for pancreatic expression of the human proglucagon gene
Authors: Zhou Li , Nian Min , Gu Jun , Irwin David M.
Published: October 2005

The mammalian proglucagon gene is expressed in pancreatic islet A-cells, intestinal L-cells, and select neurons of the brain, where posttranslational processing results in the liberation of a unique profile of peptides. Despite the importance of proglucagon-derived peptides in human biology, little is known about the regulation of the human gene, as the rat gene has been the preferred model for understanding the regulation of proglucagon gene expression. Previously, we have shown that although the immediate promoter region of the rat proglucagon gene is sufficient for expression in pancreatic islet cells, the homologous human proglucagon promoter sequences are not sufficient. We have now used a comparative genomic approach to identify noncoding sequences near the human proglucagon gene that are conserved among mammals, and thus potentially are regulatory sequences. Our alignments identified three evolutionarily conserved noncoding regions (ECR), one is the immediate promoter region (ECR1), the second is about 5 kb 5′ to the mRNA start site (ECR2), and the third is near the 3′ end of the first intron (ECR3). Our in vitro transient transfection assays with reporter gene constructs that include the human ECR3 support expression in rodent islet cell lines. Complementary studies with transgenic mice possessing a reporter gene regulated by a human proglucagon gene promoter-intron 1 (including ECR3) sequences express the reporter gene in the pancreas, as well as the intestine and selected neurons. These studies suggest that conserved sequences within intron 1 of the human proglucagon gene are important for expression in the pancreas.
Iris movement mediates vascular apoptosis during rat pupillary membrane regression
Authors: Morizane Yuki , Mohri Satoshi , Kosaka Jun , Toné Shigenobu , Kiyooka Takahiko , Miyasaka Takehiro , Shimizu Juichiro , Ogasawara Yasuo , Shiraga Fumio , Minatogawa Yohsuke , Sasaki Junzo , Ohtsuki Hiroshi , Kajiya Fumihiko
Published: October 2005

In the course of mammalian lens development, a transient capillary meshwork known as the pupillary membrane (PM) forms, which is located at the pupil area; the PM nourishes the anterior surface of the lens and then regresses to make the optical path clear. Although the involvement of apoptotic process has been reported in the PM regression, the initiating factor remains unknown. We initially found that regression of the PM coincided with the development of iris motility, and iris movement caused cessation and resumption of blood flow within the PM. Therefore, we investigated whether the development of the iris's ability to constrict and dilate functions as an essential signal that induces apoptosis in the PM. Continuous inhibition of iris movement with mydriatic agents from postnatal day 7 to day 12 suppressed apoptosis of the PM and migration of macrophage toward the PM, and resulted in the persistence of PM in rats. The distribution of apoptotic cells in the regressing PM was diffuse and showed no apparent localization. These results indicated that iris movement induced regression of the PM by changing the blood flow within it. This study suggests the importance of the physiological interactions between tissues—in this case, the iris and the PM—as a signal to advance vascular regression during organ development, and defines a novel function of the iris during ocular development in addition to the well-known function, that is, optimization of light transmission into the eye.