bluuebunny/crossref_metadata_2025 huggingface dataset:
Coherent acoustic communication in a tidal estuary with busy shipping traffic
Authors: van Walree Paul A. , Neasham Jeffrey A. , Schrijver Marco C.
Published: February 2008

High-rate acoustic communication experiments were conducted in a dynamic estuarine environment. Two current profilers deployed in a shipping lane were interfaced with acoustic modems, which modulated and transmitted the sensor readings every 200s over a period of four days. QPSK modulation was employed at a raw data rate of 8kbit∕s on a 12-kHz carrier. Two 16-element hydrophone arrays, one horizontal and one vertical, were deployed near the shore. A multichannel decision-feedback equalizer was used to demodulate the modem signals received on both arrays. Long-term statistical analysis reveals the effects of the tidal cycle, subsea unit location, attenuation by the wake of passing vessels, and high levels of ship-generated noise on the fidelity of the communication links. The use of receiver arrays enables vast improvement in the overall reliability of data delivery compared with a single-receiver system, with performance depending strongly on array orientation. The vertical array offers the best performance overall, although the horizontal array proves more robust against shipping noise. Spatial coherence estimates, variation of array aperture, and inspection of array angular responses point to adaptive beamforming and coherent combining as the chief mechanisms of array gain.
Enhanced sound transmission from water to air at low frequencies
Authors: McDonald B. Edward , Calvo David C.
Published: February 2008

Excitation of acoustic radiation into the air from a low-frequency point source under water is investigated using plane wave expansion of the source spectrum and Rayleigh reflection/transmission coefficients. Expressions are derived for the acoustic power radiated into air and water as a function of source depth and given to lowest order in the air/water density ratio. Near zero source depth, the radiation into the water is quenched by the source’s acoustic image, while the power radiated into air reaches about 1% of the power that would be radiated into unbounded water.
Restless rays, steady wave fronts
Authors: Godin Oleg A.
Published: February 2008

Observations of underwater acoustic fields with vertical line arrays and numerical simulations of long-range sound propagation in an ocean perturbed by internal gravity waves indicate that acoustic wave fronts are much more stable than the rays comprising these wave fronts. This paper provides a theoretical explanation of the phenomenon of wave front stability in a medium with weak sound-speed perturbations. It is shown analytically that at propagation ranges that are large compared to the correlation length of the sound-speed perturbations but smaller than ranges at which ray chaos develops, end points of rays launched from a point source and having a given travel time are scattered primarily along the wave front corresponding to the same travel time in the unperturbed environment. The ratio of root mean square displacements of the ray end points along and across the unperturbed wave front increases with range as the ratio of ray length to correlation length of environmental perturbations. An intuitive physical explanation of the theoretical results is proposed. The relative stability of wave fronts compared to rays is shown to follow from Fermat’s principle and dimensional considerations.
Detection and discrimination of simple and complex sounds by hearing-impaired Belgian Waterslager canaries
Authors: Lauer Amanda M. , Dooling Robert J. , Leek Marjorie R. , Poling Kirsten
Published: February 2008

Belgian Waterslager canaries (BWC) are bred to produce a distinctive low-pitched song with energy restricted to a lower range of frequencies than in other types of canaries. Previous studies have shown a high frequency hearing loss primarily above 2000Hz that is related to hair cell abnormalities in BWC, but little is known about auditory perception in these birds. Here, frequency, duration, and intensity discrimination, temporal integration, gap detection, and discrimination of temporally reversed harmonic complexes in BWC were measured and compared to normal-hearing non-BWC. BWC had excellent frequency discrimination ability at 1000Hz, but showed poor frequency discrimination compared to non-BWC at frequencies in the region of hearing loss. Duration and intensity discrimination were not adversely affected in BWC. Temporal integration was reduced in BWC, except at 2000Hz. Gap detection and discrimination of temporally reversed stimuli were somewhat better in BWC than in non-BWC. Those tests that relied primarily on temporal processing were less affected by the cochlear damage in BWC than tests that probably relied more on audibility and spectral analysis. Thus, despite significant high frequency hearing loss and extensive damage along the basilar papilla, BWC retain relatively good hearing abilities under many conditions.
Flying big brown bats emit a beam with two lobes in the vertical plane
Authors: Ghose Kaushik , Moss Cynthia F. , Horiuchi Timothy K.
Published: February 2008

The sonar beam of an echolocating bat forms a spatial window restricting the echo information returned from the environment. Investigating the shape and orientation of the sonar beam produced by a bat as it flies and performs various behavioral tasks may yield insight into the operation of its sonar system. This paper presents recordings of vertical and horizontal cross sections of the sonar beam produced by Eptesicus fuscus (big brown bats) as they fly and pursue prey in a laboratory flight room. In the horizontal plane the sonar beam consists of one large lobe and in the vertical plane the beam consists of two lobes of comparable size oriented frontally and ventrally. In level flight, the bat directs its beam such that the ventral lobe is pointed forward and down toward the ground ahead of its flight path. The bat may utilize the downward directed lobe to measure altitude without the need for vertical head movements.
The Franssen effect illusion in budgerigars (Melopsittacus undulatus) and zebra finches (Taeniopygia guttata)
Authors: Dent Micheal L. , McClaine Elizabeth M. , Welch Thomas E.
Published: February 2008

The properties of the Franssen effect (FE) were measured in budgerigars and zebra finches. To elicit the FE, listeners are presented with a signal which has been split into a transient component, carrying an abrupt onset and ramped offset and separated in space from the sustained component which has a slowly rising onset and longer duration. When these two signals are played under certain conditions, the perception is that of a long-duration steady state tone being played at the location of the transient. The birds were trained using operant conditioning methods on a categorization task to peck a left key when presented with a stimulus from a left speaker and to peck a right key when presented with a stimulus from a right speaker. Once training was completed, FE stimuli were presented during a small proportion of trials. The FE was measured at speaker separations of 60° and 180° in both echoic and echoic-reduced conditions. Both species of birds exhibited the FE, although to varying degrees, across conditions. These results show that nonmammals also experience the FE illusion in confusing listening situations in a manner similar to mammals, suggestive of similar auditory processing mechanisms.
Subbottom profiling using a ship towed line array and geoacoustic inversion
Authors: Yang T. C. , Yoo Kwang , Fialkowski L. T.
Published: February 2008

Bottom profiling traditionally uses broadband signals received on a line array at long ranges to estimate the bottom layer structure and thickness. In this paper, a subbottom profiling method is developed and applied to a ship-towed line array using the same ship towed source to estimate the subbottom layer structure and thickness. A ship towed line-array system can be used to estimate bottom properties using geoacoustic inversion and can cover a wide area in a short time. It needs some prior information about the subbottom structure and layer thickness, without which the solution can be ambiguous and even erratic when resolving parameters over a wide area. It is shown that the required subbottom information can be obtained from the time–angle relation by beamforming the same acoustic signal data used for geoacoustic inversion. The time-angle analysis is used to expose the prevalent physics intrinsic to geoacoustic inversion. One finds that the tau–p relation of the bottom and the bottom reflection coefficients, sampled at discrete angles associated with bottom and multiple surface-bottom returns, are often adequate, for many practical applications, to uniquely determine the geoacoustic bottom at low (⩽1kHz) frequencies.
Cochlear reflectivity in transmission-line models and otoacoustic emission characteristic time delays
Authors: Sisto Renata , Moleti Arturo , Shera Christopher A.
Published: February 2008

In transmission-line models of cochlear mechanics, predictions about otoacoustic-emission delays depend on the place- or wave-fixed nature of the emission generation mechanism. In this work, transient evoked otoacoustic emissions (TEOAEs), recorded at different stimulus levels in 10 young subjects, were analyzed using wavelet-based time-frequency analysis to determine the latency of each frequency component of the response. The same wave forms were Fourier analyzed to evaluate the phase-gradient delay as a function of frequency. Interpreting the relation between these two characteristic delays using cochlear models shows that most of the TEOAE response can be attributed to place-fixed reflection mechanisms. The causality principle explains observed correlations between fluctuations of the TEOAE amplitude and phase-gradient delay.
Response variance prediction for uncertain vibro-acoustic systems using a hybrid deterministic-statistical method
Authors: Langley R. S. , Cotoni V.
Published: February 2008

Imperfections during the manufacturing process can cause significant variations in the noise and vibration levels exhibited by nominally identical structures. Any response calculations employed during the design process should ideally take account of these uncertainties and predict the expected range in performance. Recently a hybrid method has been developed to predict the ensemble average response of a built-up system by combining a deterministic model of parts of the system with a statistical model of other components [Shorter, P. J., and Langley, R. S. (2005) J. Sound. Vib., 288, 669–700]. In this paper the method is extended to predict the ensemble variance of the response. Expressions are derived for the variance of the vibrational energies in the statistical components, and for the variance of the cross spectrum of the response of the deterministic components, which augment the mean values of these quantities predicted by the original theory. The method employs a nonparametric model of uncertainty, in the sense that the statistical components are taken to carry diffuse wave fields, and this obviates the requirement for a detailed description of the system uncertainties. The method is validated by application to a range of coupled plate structures, and good agreement with detailed Monte Carlo simulations is found.
Discrimination of speaker sex and size when glottal-pulse rate and vocal-tract length are controlled
Authors: Smith David R. R. , Walters Thomas C. , Patterson Roy D.
Published: February 2008

A recent study [Smith and Patterson, J. Acoust. Soc. Am. 118, 3177–3186 (2005)] demonstrated that both the glottal-pulse rate (GPR) and the vocal-tract length (VTL) of vowel sounds have a large effect on the perceived sex and age (or size) of a speaker. The vowels for all of the “different” speakers in that study were synthesized from recordings of the sustained vowels of one, adult male speaker. This paper presents a follow-up study in which a range of vowels were synthesized from recordings of four different speakers—an adult man, an adult woman, a young boy, and a young girl—to determine whether the sex and age of the original speaker would have an effect upon listeners’ judgments of whether a vowel was spoken by a man, woman, boy, or girl, after they were equated for GPR and VTL. The sustained vowels of the four speakers were scaled to produce the same combinations of GPR and VTL, which covered the entire range normally encountered in every day life. The results show that listeners readily distinguish children from adults based on their sustained vowels but that they struggle to distinguish the sex of the speaker.
Passive reverberation nulling for target enhancement
Authors: Song H. C. , Hodgkiss W. S. , Kuperman W. A. , Sabra K. G. , Akal T. , Stevenson M.
Published: February 2008

Echo-to-reverberation enhancement previously has been demonstrated using time reversal focusing when knowledge of the channel response between a target and the source array elements is available. In the absence of this knowledge, direct focusing is not possible. However, active reverberation nulling still is feasible given observations of reverberation from conventional source array transmissions. For a given range of interest, the response between the source array elements and the dominant sources of boundary reverberation is provided by the corresponding reverberation from this range. Thus, an active transmission can be projected from the source array which minimizes the energy interacting with the boundaries at a given range while still ensonifying the waveguide between the boundaries. As an alternative, here a passive reverberation nulling concept is proposed. In a similar fashion, the observed reverberation defines the response between the source array elements and the dominant sources of boundary reverberation at each range and this is used to drive a range-dependent sequence of projection operators. When these projection operators subsequently are applied to the received data vectors, reverberation can be diminished. The improvement in target detectability is demonstrated using experimental data with an echo repeater simulating the presence of a target.
A two-dimensional pseudospectral model for time reversal and nonlinear elastic wave spectroscopy
Authors: Goursolle Thomas , Callé Samuel , Dos Santos Serge , Bou Matar Olivier
Published: February 2008

One way to characterize metallic materials in the presence of defects like dislocation networks is to measure their large dynamic nonlinear elastic response. In this numerical study, a new method combining the nonlinear elastic wave spectroscopy (NEWS) method with a time reversal (TR) process is proposed. This method, called NEWS-TR, uses nonlinear analysis as a pretreatment of time reversal and then consists of retrofocusing only nonlinear components on the defect position. A two-dimensional pseudospectral time domain algorithm is developed here to validate the NEWS-TR method as a potential technique for damage location. Hysteretic nonlinear behavior of the materials being studied is introduced using the Preisach-Mayergoyz model. Moreover, in order to extend this solver in two dimensions, the Kelvin notation is used to modify the elastic coefficient tensor. Simulations performed on a metallic sample show the feasibility and value of the NEWS-TR methodology for microdamage imaging. Retrofocusing quality depends on different parameters such as the filtering method used to keep only nonlinear components and the nonlinear effect measured. In harmonic generation, pulse inversion filtering seems to be a more appropriate filtering method than classical harmonic filtering for most defect positions, mainly because of its ability to filter all fundamental components.
Seasonal variability and detection range modeling of baleen whale calls in the Gulf of Alaska, 1999–2002
Authors: Stafford Kathleen M. , Mellinger David K. , Moore Sue E. , Fox Christopher G.
Published: February 2008

Five species of large whales, including the blue (Balaenoptera musculus), fin (B. physalus), sei (B. borealis), humpback (Megaptera novaeangliae), and North Pacific right (Eubalaena japonica), were the target of commercial harvests in the Gulf of Alaska (GoA) during the 19th through mid-20th Centuries. Since this time, there have been a few summer time visual surveys for these species, but no overview of year-round use of these waters by endangered whales primarily because standard visual survey data are difficult and costly. From October 1999–May 2002, moored hydrophones were deployed in six locations in the GoA to record whale calls. Reception of calls from fin, humpback, and blue whales and an unknown source, called Watkins’ whale, showed seasonal and geographic variation. Calls were detected more often during the winter than during the summer, suggesting that animals inhabit the GoA year-round. To estimate the distance at which species-diagnostic calls could be heard, parabolic equation propagation loss models for frequencies characteristic of each of each call type were run. Maximum detection ranges in the subarctic North Pacific ranged from 45to250km among three species (fin, humpback, blue), although modeled detection ranges varied greatly with input parameters and choice of ambient noise level.
Intra- and intergroup vocal behavior in resident killer whales, Orcinus orca
Authors: Weiß Brigitte M. , Symonds Helena , Spong Paul , Ladich Friedrich
Published: February 2008

Vocal communication within and between groups of individuals has been described extensively in birds and terrestrial mammals, however, little is known about how cetaceans utilize their sounds in their natural environment. Resident killer whales, Orcinus orca, live in highly stable matrilines and exhibit group-specific vocal dialects. Single call types cannot exclusively be associated with particular behaviors and calls are thought to function in group identification and intragroup communication. In the present study call usage of three closely related matrilines of the Northern resident community was compared in various intra- and intergroup contexts. In two out of the three matrilines significant changes in vocal behavior depending both on the presence and identity of accompanying whales were found. Most evidently, family-specific call subtypes, as well as aberrant and variable calls, were emitted at higher rates, whereas “low arousal” call types were used less in the presence of matrilines from different pods, subclans, or clans. Ways in which the observed changes may function both in intra- and intergroup communication.
Wavelet and matching pursuit estimates of the transient-evoked otoacoustic emission latency
Authors: Notaro Giuseppe , Al-Maamury Adnan Mohsin , Moleti Arturo , Sisto Renata
Published: February 2008

Different time–frequency techniques may be used to investigate the relation between latency and frequency of transient-evoked otoacoustic emissions. In this work, the optimization of these techniques and the interpretation of the experimental result are discussed. Time–frequency analysis of click-evoked otoacoustic emissions of 42 normal-hearing young subjects has been performed, using both wavelet and matching pursuit algorithms. Wavelet techniques are very effective to provide fast and reliable evaluation of the average latency of large samples of subjects. A major advantage of the matching pursuit technique, as observed by Jedrzejczak et al. [J. Acoust. Soc. Am. 115, 2148–2158 (2004)], is to provide detailed information about the time evolution of the response of single ears at selected frequencies. A hybrid matching pursuit algorithm that includes Fourier spectral information was developed, capable of speeding-up computation times and of identifying “spurious” atoms, whose latency-frequency relation is apparently anomalous. These atoms could be associated with several known phenomena, either intrinsic, such as intermodulation distortion, spontaneous emissions and multiple internal reflections, or extrinsic, such as instrumental noise, linear ringing and the acquisition window onset. A correct interpretation of these phenomena is important to get accurate estimates of the otoacoustic emission latency.
Entrainment and stimulated emission of ultrasonic piezoelectric auto-oscillators
Authors: Weaver Richard L. , Lobkis Oleg I. , Yamilov Alexey
Published: February 2008

Theoretical modeling and laboratory tests are conducted for nonlinear auto-oscillating piezoelectric ultrasonic devices coupled to reverberant elastic bodies. The devices are shown to exhibit behavior familiar from the theory of coupled auto-oscillators. In particular, these spontaneously emitting devices adjust their limit-cycle frequency to the spectrum of the body. It is further shown that the auto-oscillations can be entrained by an applied field; an incident wave at a frequency close to the frequency of the natural limit cycle entrains the oscillator. Special attention is paid to the phase of entrainment. Depending on details, the phase is such that the oscillator can be in a state of stimulated emission: the incident field amplifies the ultrasonic power emitted by the oscillator. These behaviors are essential to eventual design of an ultrasonic system that would consist of a number of such devices all synchronized to their mutual field, a system that would be an analog to a laser. A prototype uaser is constructed.
Histology-based simulations for the ultrasonic detection of microscopic cancer in vivo
Authors: Doyle Timothy E. , Warnick Keith H. , Carruth Brent L.
Published: February 2008

Ultrasonic spectroscopy may offer an alternative to imaging methods for the in vivo detection of microscopic cancer. To investigate this potential, a numerical model that incorporates multiple scattering, wave-mode conversion, and hierarchical microstructures was developed to simulate ultrasonic interactions in biological tissue at the microscopic level. Simulated high-frequency (20–75MHz) spectra of up to 2137 cells displayed significant correlations to nucleus diameter and malignant cell infiltration, and indicated as few as 300 malignant cells may be detectable in normal tissue. The results suggest that ultrasonic spectroscopy combined with simulation-based interpretive models may provide real-time histopathology during surgeries, biopsies, and endoscopies.
The integrated extinction for broadband scattering of acoustic waves
Authors: Sohl Christian , Gustafsson Mats , Kristensson Gerhard
Published: February 2008

In this paper, physical bounds on scattering of acoustic waves over a frequency interval are discussed based on the holomorphic properties of the scattering amplitude in the forward direction. The result is given by a dispersion relation for the extinction cross section which yields an upper bound on the product of the extinction cross section and the associated bandwidth of any frequency interval. The upper bound is shown to depend only on the geometry and the material properties of the scatterer in the static or low-frequency limit. The results are exemplified by permeable and impermeable scatterers with homogeneous and isotropic material properties.
Perceiving the speech of multiple concurrent talkers in a combined divided and selective attention task
Authors: Shafiro Valeriy , Gygi Brian
Published: February 2008

Detection and identification of concurrently spoken key words was investigated using the Coordinate Response Measure corpus. On every trial, listeners first had to explicitly detect callsign keywords in a multi-talker stimulus (divided attention), and, if all callsigns were present, identify the color and number words produced by one of the talkers (selective attention). Increasing the number of concurrent talkers and the number of callsigns to be detected each had a marked negative effect on detection and identification performance. These findings indicate that, when memory involvement is limited, listeners cannot reliably detect more than two concurrently spoken words in diotic listening.
Sequence Variants in the
RNF212
Gene Associate with Genome-Wide Recombination Rate
Authors: Kong Augustine , Thorleifsson Gudmar , Stefansson Hreinn , Masson Gisli , Helgason Agnar , Gudbjartsson Daniel F. , Jonsdottir Gudrun M. , Gudjonsson Sigurjon A. , Sverrisson Sverrir , Thorlacius Theodora , Jonasdottir Aslaug , Hardarson Gudmundur A. , Palsson Stefan T. , Frigge Michael L. , Gulcher Jeffrey R. , Thorsteinsdottir Unnur , Stefansson Kari
Published: February 2008

The genome-wide recombination rate varies between individuals, but the mechanism controlling this variation in humans has remained elusive. A genome-wide search identified sequence variants in the 4p16.3 region correlated with recombination rate in both males and females. These variants are located in the
RNF212
gene, a putative ortholog of the
ZHP-3
gene that is essential for recombinations and chiasma formation in
Caenorhabditis elegans
. It is noteworthy that the haplotype formed by two single-nucleotide polymorphisms (SNPs) associated with the highest recombination rate in males is associated with a low recombination rate in females. Consequently, if the frequency of the haplotype changes, the average recombination rate will increase for one sex and decrease for the other, but the sex-averaged recombination rate of the population can stay relatively constant.
Human-Induced Changes in the Hydrology of the Western United States
Authors: Barnett Tim P. , Pierce David W. , Hidalgo Hugo G. , Bonfils Celine , Santer Benjamin D. , Das Tapash , Bala Govindasamy , Wood Andrew W. , Nozawa Toru , Mirin Arthur A. , Cayan Daniel R. , Dettinger Michael D.
Published: February 2008

Observations have shown that the hydrological cycle of the western United States changed significantly over the last half of the 20th century. We present a regional, multivariable climate change detection and attribution study, using a high-resolution hydrologic model forced by global climate models, focusing on the changes that have already affected this primarily arid region with a large and growing population. The results show that up to 60% of the climate-related trends of river flow, winter air temperature, and snow pack between 1950 and 1999 are human-induced. These results are robust to perturbation of study variates and methods. They portend, in conjunction with previous work, a coming crisis in water supply for the western United States.
Descriptive epidemiology of drowning deaths in a surf beach swimmer and surfer population
Authors: Morgan D , Ozanne-Smith J , Triggs T
Published: February 2008

Retrospective data extraction from two complementary mortality datasets determined the descriptive epidemiology and population rates in unintentional drowning deaths at surf beaches (n = 129). The annual average crude surf beach drowning rate was 0.28 per 100 000 population for males and 2.36 per 100 000 population for international tourists. The study generated hypotheses for risk assessment to assist intervention: adult males, international tourists, people with cardiovascular conditions, and exposure to rip currents.
Effectiveness of a law to reduce alcohol-impaired driving in Japan
Authors: Nagata T , Setoguchi S , Hemenway D , Perry M J
Published: February 2008

Objective:

To estimate the effect of a new road traffic law against alcohol-impaired driving in Japan.

Methods:

Japan passed a new road traffic law in June 2002 intended to reduce alcohol-impaired driving by decreasing the permissible blood alcohol level and by increasing penalties. Using data collected from police reports, the number of traffic fatalities and injuries were analyzed by time series.

Results:

Simple comparisons of the average of all severe traffic injuries, traffic fatalities, alcohol-impaired traffic injuries, alcohol-impaired severe traffic injuries, and alcohol-impaired traffic fatalities per billion kilometers driven showed reductions after enactment of the new road traffic law in June 2002. The rate of alcohol-related traffic fatalities per billion kilometers driven decreased by 38% in the post-law period. In segmented regression analyses with adjustment for baseline trends, seasonality, and autocorrelation, all traffic injuries, severe traffic injuries, alcohol-impaired traffic injuries, alcohol-impaired severe traffic injuries, and alcohol-impaired traffic fatalities per billion kilometers driven declined significantly from baseline after the new traffic law.

Conclusion:

Large, immediate public health benefits resulted from the new road traffic law in Japan.
Driving miles estimates by teen drivers: how accurate are they?
Authors: Leaf W A , Simons-Morton B G , Hartos J L , Northrup V Shabanova
Published: February 2008

The objective of this study was to determine how accurately teens can report miles driven. Participants were 118 drivers in Connecticut (average age 17½ years; average time licensed 11 months). Half had their own vehicle; half shared family vehicles. Teens completed a telephone survey about their preceding week’s driving, then completed a daily trip log for the next week and a second survey about the details of the logged week’s trips and miles. Teens with their own vehicle provided odometer readings. Summing the miles for every trip was generally consistent with estimates from odometer readings. Overall mileage estimates were 20–30% lower than those from trip-by-trip listings, except for very low estimates for the first week by teens who shared vehicles. The results indicate that single overall estimates frequently understate total miles driven, but that prompted reviews of each trip can provide valid and detailed information.
Stable age pattern supports role of development in unintentional childhood poisoning
Authors: Schmertmann M , Williamson A , Black D
Published: February 2008

Objective:

To investigate if child development has a role in unintentional poisoning, by describing the pattern of hospitalization due to unintentional poisoning in children aged 0–4 years in New South Wales by single year of age and then assessing the stability of the age-specific pattern found when analyzed by sex, remoteness of residence, and socioeconomic status.

Design:

Retrospective descriptive study.

Setting:

New South Wales hospitals from 1994 to 2005.

Participants:

Children aged 0–4 years in the New South Wales Department of Health Inpatient Statistics Collection.

Main exposure:

Hospitalization due to unintentional poisoning.

Main outcome measures:

Hospitalization rates by single year of age and single year of age by three covariates: sex, remoteness of residence, and socioeconomic status.

Results:

Children aged 1–3 years had the highest rates of hospitalization due to unintentional poisoning, and this pattern persisted over time. The same age-specific pattern was seen for both boys and girls, but rates were significantly higher for boys than girls at age 3 years (RR = 1.46, 95% CI 1.31 to 1.62). The age-specific pattern persisted when the covariates remoteness of residence and socioeconomic status were controlled for.

Conclusion:

The age-specific pattern of hospitalization for unintentional poisoning by single year of age was found to be stable when analyzed over time and by sex, remoteness of residence, and socioeconomic status. This finding provides strong evidence for the role of a child’s development in an unintentional poisoning event.
Bile acids modulate tight junction structure and barrier function of Caco-2 monolayers via EGFR activation
Authors: Raimondi Francesco , Santoro Pasquale , Barone Maria Vittoria , Pappacoda Serena , Barretta Maria Luisa , Nanayakkara Merlin , Apicella Carmela , Capasso Letizia , Paludetto Roberto
Published: February 2008

Intestinal and systemic illnesses have been linked to increased gut permeability. Bile acids, whose luminal profile can be altered in human disease, modulate intestinal paracellular permeability. We investigated the mechanism by which selected bile acids increase gut permeability using a validated in vitro model. Human intestinal Caco-2 cells were grown in monolayers and challenged with a panel of bile acids. Transepithelial electrical resistance and luminal-to-basolateral fluxes of 10-kDa Cascade blue-conjugated dextran were used to monitor paracellular permeability. Immunoprecipitation and immunoblot analyses were employed to investigate the intracellular pathway. Redistribution of tight junction proteins was studied by confocal laser microscopy. Micromolar concentrations of cholic acid, deoxycholic acid (DCA), and chenodeoxycholic acid (CDCA) but not ursodeoxycholic acid decreased transepithelial electrical resistance and increased dextran flux in a reversible fashion. Coincubation of 50 μM CDCA or DCA with EGF, anti-EGF monoclonal antibody, or specific src inhibitor 4-Amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP-2) abolished the effect. A concentration of 50 μM of either CDCA or DCA also induced EGF receptor phosphorylation, occludin dephosphorylation, and occludin redistribution at the tight junction level in the same time frame and in a reversible fashion. We conclude that selected bile acids modulate intestinal permeability via EGF receptor autophosphorylation, occludin dephosphorylation, and rearrangement at the tight junction level. The effect is mediated by the src family kinases and is abolished by EGF treatment. These data also support the role of bile acids in the genesis of necrotizing enterocolitis and the protective effect of EGF treatment.
Manometric evidence for a phonation-induced UES contractile reflex
Authors: Perera Lilani , Kern Mark , Hofmann Candy , Tatro Linda , Chai Krisna , Kuribayashi Shiko , Lawal Adeyemi , Shaker Reza
Published: February 2008

The mechanism against entry of gastric content into the pharynx during high-intensity vocalization such as seen among professional singers is not known. We hypothesized that phonation-induced upper esophageal sphincter (UES) contraction enhances the pressure barrier against entry of gastroesophageal contents into pharynx. To determine and compare the effect of phonation on luminal pressures of the esophagus and its sphincters, we studied 17 healthy volunteers (7 male, 10 female) by concurrent high-resolution manometry and voice analysis. We tested high- and low-pitch vowel sounds. Findings were verified in six subjects by UES manometry using a water-perfused sleeve device. Eight of the volunteers (2 male, 6 female) had concurrent video fluoroscopy with high-resolution manometry and voice recording. Fluoroscopic images were analyzed for laryngeal movement. To define the sex-based effect, subgroup analysis was performed. All tested phonation frequencies and intensities induced a significant increase in UES pressure (UESP) compared with prephonation pressure. The magnitude of the UESP increase was significantly higher than that of the distal esophagus, the lower esophageal sphincter (LES), and the stomach. Concurrent videofluoroscopy did not show posterior laryngeal movement during phonation, eliminating a purely mechanical cause for phonation-induced UESP increase. Subgroup analysis demonstrated phonation-induced UESP increases in males that were significantly greater than those of females. Phonation induces a significant increase in UESP, suggesting the existence of a phonation-induced UES contractile reflex. UESP increase due to this reflex is significantly higher than that of the distal esophagus, LES, and stomach. The phonation-induced UESP increase is influenced by sex.
Endocannabinoids and Liver Disease. III. Endocannabinoid effects on immune cells: implications for inflammatory liver diseases
Authors: Pacher Pál , Gao Bin
Published: February 2008

Recent studies have implicated dysregulation of the endocannabinoid system in various liver diseases and their complications (e.g., hepatitis, fibrosis, cirrhosis, cirrhotic cardiomyopathy, and ischemia-reperfusion), and demonstrated that its modulation by either cannabinoid 2 (CB2) receptor agonists or CB1 antagonists may be of significant therapeutic benefits. This review is aimed to focus on the triggers and sources of endocannabinoids during liver inflammation and on the novel role of CB2 receptors in the interplay between the activated endothelium and various inflammatory cells (leukocytes, lymphocytes, etc.), which play pivotal role in the early development and progression of inflammatory and other liver diseases.
Phosphatidylinositol 3-kinase/Akt signaling mediates interleukin-32α induction in human pancreatic periacinar myofibroblasts
Authors: Nishida Atsushi , Andoh Akira , Shioya Makoto , Kim-Mitsuyama Shokei , Takayanagi Atsushi , Fujiyama Yoshihide
Published: February 2008

Interleukin (IL)-32 is a recently described proinflammatory cytokine, characterized by the induction of nuclear factor (NF)-κB activation. We studied IL-32α expression in human pancreatic periacinar myofibroblasts, which play important roles in the regulation of extracellular matrix metabolism and inflammatory responses in the pancreas. IL-32α protein expression was evaluated by Western blot analyses, and IL-32α mRNA expression was analyzed by Northern blot and real-time PCR analyses. IL-32α mRNA was weakly expressed without a stimulus, and its expression was markedly enhanced by IL-1β, IFN-γ, and TNF-α. IL-1β, IFN-γ, and TNF-α enhanced intracellular accumulation of IL-32α protein, but IL-32α was not detected in supernatants. Each cytokine dose and time dependently induced IL-32α mRNA expression. An inhibitor of phosphatidylinositol 3-kinase (LY294002) significantly suppressed IL-1β-, IFN-γ-, and TNF-α-induced IL-32α mRNA expression, although MAPK inhibitors had no effect. Akt activation in response to these cytokines was confirmed by Western blot. Furthermore, LY294002 suppressed both IL-1β- and TNF-α-induced NF-κB activation and IL-1β-, TNF-α-, and IFN-γ-induced activated protein-1 (AP-1) activation. Blockade of NF-κB and AP-1 activation by an adenovirus expressing a stable mutant form of IκBα and a dominant negative mutant of c-Jun markedly suppressed IL-1β-, IFN-γ-, and/or TNF-α-induced IL-32α mRNA expression. Human pancreatic periacinar myofibroblasts expressed IL-32α in response to IL-1β, TNF-α, and IFN-γ. IL-32α mRNA expression is dependent on interactions between the phosphatidylinositol 3-kinase/Akt-pathway and the NF-κB/AP-1 system.
The Adventures of Sonic Hedgehog in Development and Repair. III. Hedgehog processing and biological activity
Authors: Farzan Shohreh F. , Singh Samer , Schilling Neal S. , Robbins David J.
Published: February 2008

The Hedgehog (Hh) family of secreted proteins is necessary for aspects of the development and maintenance of the gastrointestinal tract. Hh is thought to function as a morphogen, a mitogen, a cell survival factor, and an axon guidance factor. Given its wide role in development, as well as in a variety of disease states, understanding the regulation of Hh function and activity is critically important. However, the study of Hh signaling has been impeded by its unusual biology. Hh is unique in that it is the only protein covalently modified by cholesterol, which in turn affects numerous aspects of its localization, release, movement, and activity. All are important factors when considering Hh's physiological role, and animals have developed an intricate system of regulators responsible for both promoting and inhibiting the activity of Hh. This review is intended to give a broad overview of how the biosynthesis and movement of Hh contributes to its biological activity.
Effects of a Rho kinase inhibitor on pressure overload induced cardiac hypertrophy and associated diastolic dysfunction
Authors: Phrommintikul Arintaya , Tran Lavinia , Kompa Andrew , Wang Bing , Adrahtas Anastasia , Cantwell Danielle , Kelly Darren J. , Krum Henry
Published: February 2008

The RhoA-Rho kinase (ROCK) signaling pathway has an important role in cardiovascular diseases. However, the effect of Rho kinase inhibition on pressure overload-induced cardiac hypertrophy (POH) and associated diastolic dysfunction has not been evaluated. This study examined the effect of a selective ROCK inhibitor (GSK-576371) in a POH model, induced by suprarenal abdominal aortic constriction. POH rats were divided into the following four groups: 1 (GSK 1, n = 9) or 3 (GSK 3, n = 10) mg/kg bid GSK-576371, 1 mg·kg−1·day−1 ramipril ( n = 10) or vehicle ( n = 11) treatment for 4 wk. Sham animals ( n = 11) underwent surgery without banding. Echocardiograms were performed before surgery and posttreatment, and hemodynamic data were obtained at completion of the study. Echocardiography showed an increase in relative wall thickness of the left ventricle (LV) following POH + vehicle treatment compared with sham animals. This was attenuated by both doses of GSK-576371 and ramipril. Vehicle treatment demonstrated abnormal diastolic parameters, including mitral valve (MV) inflow E wave deceleration time, isovolumic relaxation time, and MV annular velocity, which were dose dependently restored toward sham values by GSK-576371. LV end diastolic pressure was increased following POH + vehicle treatment compared with sham (6.9 ± 0.7 vs. 3.2 ± 0.7 mmHg, P = 0.008) and was reduced with GSK 3 and ramipril treatment (1.7 ± 0.7, P < 0.01 and 2.9 ± 0.6 mmHg, P < 0.01, respectively). Collagen I deposition in the LV was increased following POH + vehicle treatment (32.2%; P < 0.01) compared with sham animals and was significantly attenuated with GSK 1 (21.7%; P < 0.05), GSK 3 (23.8%; P < 0.01), and ramipril (35.5%; P < 0.01) treatment. These results suggest that ROCK inhibition improves LV geometry and reduces collagen deposition accompanied by improved diastolic function in POH.
Effect of exercise on biological pathways in ApcMin/+ mouse intestinal polyps
Authors: Baltgalvis Kristen A. , Berger Franklin G. , Peña Maria Marjorette O. , Davis J. Mark , Carson James A.
Published: February 2008

Many epidemiological studies have demonstrated that level of exercise is associated with reduced colorectal cancer risk. Treadmill training can decrease Apc Min/+ mouse intestinal polyp number and size, but the mechanisms remain unclear. Understanding the molecular changes in the tumor following exercise training may provide insight on the mechanism by which exercise decreases Apc Min/+ mouse polyp formation and growth. The purpose of this study was to determine if exercise can modulate Apc Min/+ mouse intestinal polyp cellular signaling related to tumor formation and growth. Male Apc Min/+ mice were randomly assigned to control ( n = 20) or exercise ( n = 20) treatment groups. Exercised mice ran on a treadmill at a moderate intensity (18 m/min, 60 min, 6 days/wk, 5% grade) for 9 wk. Polyps from Apc Min/+ mice were used to quantify markers of polyp inflammation, apoptosis, and β-catenin signaling. Exercise decreased the number of macrophages in polyps by 35%. Related to apoptosis, exercise decreased the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells by 73% in all polyps. Bax protein expression in polyps was decreased 43% by exercise. β-Catenin phosphorylation was elevated 3.3-fold in polyps from exercised mice. Moderate-intensity exercise training alters cellular pathways in Apc Min/+ mouse polyps, and these changes may be related to the exercise-induced reduction in polyp formation and growth.
Muscle-specific expression of PPARγ coactivator-1α improves exercise performance and increases peak oxygen uptake
Authors: Calvo Jennifer A. , Daniels Thomas G. , Wang Xiaomei , Paul Angelika , Lin Jiandie , Spiegelman Bruce M. , Stevenson Susan C. , Rangwala Shamina M.
Published: February 2008

The induction of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a key regulator of mitochondriogenesis, is well-established under multiple physical exercise regimens, including, endurance, resistance, and sprint training. We wanted to determine if increased expression of PGC-1α in muscle is sufficient to improve performance during exercise in vivo. We demonstrate that muscle-specific expression of PGC-1α improves the performance during voluntary as well as forced exercise challenges. Additionally, PGC-1α transgenic mice exhibit an enhanced performance during a peak oxygen uptake exercise test, demonstrating an increased peak oxidative capacity, or whole body oxygen uptake. This increased ability to perform in multiple exercise paradigms is supported by enhanced mitochondrial function as suggested by increased mitochondrial gene expression, mitochondrial DNA, and mitochondrial enzyme activity. Thus this study demonstrates that upregulation of PGC-1α in muscle in vivo is sufficient to greatly improve exercise performance under various exercise paradigms as well as increase peak oxygen uptake.
Genotoxic Stress–Induced Expression of p53 and Apoptosis in Leukemic Clam Hemocytes with Cytoplasmically Sequestered p53
Authors: Böttger Stefanie , Jerszyk Emily , Low Ben , Walker Charles
Published: February 2008

In nature, the soft shell clam, Mya arenaria, develops a fatal blood cancer in which a highly conserved homologue for wild-type human p53 protein is rendered nonfunctional by cytoplasmic sequestration. In untreated leukemic clam hemocytes, p53 is complexed throughout the cytoplasm with overexpressed variants for both clam homologues (full-length variant, 1,200-fold and truncated variant, 620-fold above normal clam hemocytes) of human mortalin, an Hsp70 family protein. In vitro treatment with etoposide only and in vivo treatment with either etoposide or mitoxantrone induces DNA damage, elevates expression (600-fold) and promotes nuclear translocation of p53, and results in apoptosis of leukemic clam hemocytes. Pretreatment with wheat germ agglutinin followed by etoposide treatment induces DNA damage and elevates p53 expression (893-fold) but does not overcome cytoplasmic sequestration of p53 or induce apoptosis. We show that leukemic clam hemocytes have an intact p53 pathway, and that maintenance of this tumor phenotype requires nuclear absence of p53, resulting from its localization in the cytoplasm of leukemic clam hemocytes. The effects of these topoisomerase II poisons may result as mortalin-based cytoplasmic tethering is overwhelmed by de novo expression of p53 protein after DNA damage induced by genotoxic stress. Soft shell clam leukemia provides excellent in vivo and in vitro models for developing genotoxic and nongenotoxic cancer therapies for reactivating p53 transcription in human and other animal cancers displaying mortalin-based cytoplasmic sequestration of the p53 tumor suppressor, such as colorectal cancers and primary and secondary glioblastomas, though not apparently leukemias or lymphomas. [Cancer Res 2008;68(3):777–82]
DR5 Receptor Mediates Anoikis in Human Colorectal Carcinoma Cell Lines
Authors: Laguinge Luciana M. , Samara Raed N. , Wang Wenge , El-Deiry Wafik S. , Corner Georgia , Augenlicht Leonard , Mishra Lopa , Jessup J. Milburn
Published: February 2008

As human colorectal cancer (CRC) cells metastasize to distant sites, they are susceptible to detachment-induced cell death or anoikis — a form of apoptosis that occurs when anchorage-dependent CRC cells go into suspension. Our goal was to identify whether tumor necrosis factor receptor apoptosis-inducing ligand (TRAIL) receptors mediate anoikis in human CRC cells. First, we assessed whether caspases of the extrinsic (caspase-8) or intrinsic (caspase-9) death pathways were involved. Caspase-8 was cleaved during exposure to suspension culture in four CRC lines, and cell death was inhibited by caspase-3 and caspase-8 inhibitors but not by a caspase-9 inhibitor. Gene transcripts in macrophage inflammatory protein-101 (MIP-110), a weakly metastatic human CRC, were increased at least 2-fold for TRAIL-R2 (DR5) and TRAIL after 24 h of suspension culture compared with cells in monolayer culture. The increased expression of DR5 was confirmed at the protein level at 24 h, and exposure of MIP-101 cells to an antagonistic antibody to DR5 decreased caspase-8 activation. The antagonistic antibody to DR5 inhibited anoikis in four human CRC lines. Treatment with an antagonistic DR4 antibody or a neutralizing antibody to TRAIL ligand did not reduce anoikis consistently. Knockdown of DR5 or TRAIL also inhibited anoikis, whereas exogenous TRAIL or FasL did not consistently increase anoikis. In summary, DR5 receptor mediates death signals for anoikis in human CRC cells through the extrinsic apoptotic pathway. [Cancer Res 2008;68(3):909–17]