bluuebunny/crossref_metadata_2025 huggingface dataset:
Discrimination of interaural phase differences in the envelopes of sinusoidally amplitude-modulated 4-kHz tones as a function of modulation depth
Authors: Stellmack Mark A. , Viemeister Neal F. , Byrne Andrew J.
Published: June 2005

Psychometric functions were measured for the discrimination of the interaural phase difference (IPD) of the envelope of a sinusoidally amplitude-modulated (SAM) 4-kHz pure tone for modulation frequencies of 128 and 300 Hz and modulation depths (m) of 0.2, 0.6, 0.9, and 1.0. Contrary to recent modeling assumptions, it was found that a constant change in normalized interaural envelope correlation, with or without additional model stages to simulate peripheral auditory processing, did not produce a constant level of performance. Rather, in some cases, performance could range from chance to near perfect across modulation depths for a given change in normalized interaural envelope correlation. This was also true for the maximum change in normalized interaural envelope correlation computed across the cross-correlation functions for the stimuli to be discriminated. The change in the interaural time difference (ITD) computed from the IPD accounted for discriminability across modulation depths better than the change in normalized interaural envelope correlation, although ITD could not account for all the data, particularly those for lower values of m.
Toward a theory of wave energy transport in large irregular structures
Authors: Wolff Nicholas L. , Weaver Richard L.
Published: June 2005

An ansatz is proposed by which the energy transport behavior observed at early times in a direct numerical simulation (DNS) of a large irregular structure may be extrapolated to arbitrary times. In the slow-transport limit, this ansatz leads to a diffusion-like equation, similar to that of time-domain statistical energy analysis (SEA), but it does not require substructuring. The model is successfully used to extract diffusion parameters from simulated data of unambiguously diffusive character. The model is then successfully used to extract diffusion parameters from data obtained in a DNS of a simple undamped two-room structure of a kind typically analyzed by SEA or room acoustics.
Estimation of the location of a farfield acoustic source
Authors: Hardin Jay C. , Gilinsky Mikhail , Khaikine Vitali
Published: June 2005

A backward integration method for estimating the location of a source of sound waves in the atmosphere is presented. This geometric acoustics method is based upon the analysis of microphone array measurements to determine the incoming ray direction in three dimensions. The equations governing the propagation of the ray are then integrated backward in time. The sound source lies somewhere along the calculated ray path. The intersection of such loci from more than one array would provide an estimate of the source location. The method appears to be very rapid to implement and, assuming the time delays to be accurately measured, limited in accuracy only by the timeliness of the input sound speed and velocity profiles in the atmosphere.
The role of high frequencies in speech localization
Authors: Best Virginia , Carlile Simon , Jin Craig , van Schaik André
Published: June 2005

This study measured the accuracy with which human listeners can localize spoken words. A broadband (300Hz–16kHz) corpus of monosyllabic words was created and presented to listeners using a virtual auditory environment. Localization was examined for 76 locations on a sphere surrounding the listener. Experiment 1 showed that low-pass filtering the speech sounds at 8kHz degraded performance, causing an increase in polar angle errors associated with the cone of confusion. In experiment 2 it was found that performance in fact varied systematically with the level of the signal above 8kHz. Although the lower frequencies (below 8kHz) are known to be sufficient for accurate speech recognition in most situations, these results demonstrate that natural speech contains information between 8 and 16kHz that is essential for accurate localization.
Acoustic correlates of timbre space dimensions: A confirmatory study using synthetic tones
Authors: Caclin Anne , McAdams Stephen , Smith Bennett K. , Winsberg Suzanne
Published: June 2005

Timbre spaces represent the organization of perceptual distances, as measured with dissimilarity ratings, among tones equated for pitch, loudness, and perceived duration. A number of potential acoustic correlates of timbre-space dimensions have been proposed in the psychoacoustic literature, including attack time, spectral centroid, spectral flux, and spectrum fine structure. The experiments reported here were designed as direct tests of the perceptual relevance of these acoustical parameters for timbre dissimilarity judgments. Listeners presented with carefully controlled synthetic tones use attack time, spectral centroid, and spectrum fine structure in dissimilarity rating experiments. These parameters thus appear as major determinants of timbre. However, spectral flux appears as a less salient timbre parameter, its salience depending on the number of other dimensions varying concurrently in the stimulus set. Dissimilarity ratings were analyzed with two different multidimensional scaling models (CLASCAL and CONSCAL), the latter providing psychophysical functions constrained by the physical parameters. Their complementarity is discussed.
Parameter fitting for piano sound synthesis by physical modeling
Authors: Bensa Julien , Gipouloux Olivier , Kronland-Martinet Richard
Published: June 2005

A difficult issue in the synthesis of piano tones by physical models is to choose the values of the parameters governing the hammer–string model. In fact, these parameters are hard to estimate from static measurements, causing the synthesis sounds to be unrealistic. An original approach that estimates the parameters of a piano model, from the measurement of the string vibration, by minimizing a perceptual criterion is proposed. The minimization process that was used is a combination of a gradient method and a simulated annealing algorithm, in order to avoid convergence problems in case of multiple local minima. The criterion, based on the tristimulus concept, takes into account the spectral energy density in three bands, each allowing particular parameters to be estimated. The optimization process has been run on signals measured on an experimental setup. The parameters thus estimated provided a better sound quality than the one obtained using a global energetic criterion. Both the sound’s attack and its brightness were better preserved. This quality gain was obtained for parameter values very close to the initial ones, showing that only slight deviations are necessary to make synthetic sounds closer to the real ones.
Sound radiation around a flying fly
Authors: Sueur Jérôme , Tuck Elizabeth J. , Robert Daniel
Published: June 2005

Many insects produce sounds during flight. These acoustic emissions result from the oscillation of the wings in air. To date, most studies have measured the frequency characteristics of flight sounds, leaving other acoustic characteristics—and their possible biological functions—unexplored. Here, using close-range acoustic recording, we describe both the directional radiation pattern and the detailed frequency composition of the sound produced by a tethered flying (Lucilia sericata). The flapping wings produce a sound wave consisting of a series of harmonics, the first harmonic occurring around 190Hz. In the horizontal plane of the fly, the first harmonic shows a dipolelike amplitude distribution whereas the second harmonic shows a monopolelike radiation pattern. The first frequency component is dominant in front of the fly while the second harmonic is dominant at the sides. Sound with a broad frequency content, typical of that produced by wind, is also recorded at the back of the fly. This sound qualifies as pseudo-sound and results from the vortices generated during wing kinematics. Frequency and amplitude features may be used by flies in different behavioral contexts such as sexual communication, competitive communication, or navigation within the environment.
A suppressor to prevent direct wave-induced cavitation in shock wave therapy devices
Authors: Matula Thomas J. , Hilmo Paul R. , Bailey Michael R.
Published: June 2005

Cavitation plays a varied but important role in lithotripsy. Cavitation facilitates stone comminution, but can also form an acoustic barrier that may shield stones from subsequent shock waves. In addition, cavitation damages tissue. Spark-gap lithotripters generate cavitation with both a direct and a focused wave. The direct wave propagates as a spherically diverging wave, arriving at the focus ahead of the focused shock wave. It can be modeled with the same waveform (but lower amplitude) as the focused wave. We show with both simulations and experiments that bubbles are forced to grow in response to the direct wave, and that these bubbles can still be large when the focused shock wave arrives. A baffle or “suppressor” that blocks the propagation of the direct wave is shown to significantly reduce the direct wave pressure amplitude, as well as direct wave-induced bubble growth. These results are applicable to spark-gap lithotripters and extracorporeal shock wave therapy devices, where cavitation from the direct wave may interfere with treatment. A simple direct-wave suppressor might therefore be used to improve the therapeutic efficacy of these devices.
On the performance of automated porpoise-click-detectors in experiments with captive harbor porpoises (Phocoena phocoena)
Authors: Thomsen Frank , Elk Niels van , Brock Vilmut , Piper Werner
Published: June 2005

Recently, automated porpoise-click-detectors (T-PODs, Chelonia-Marine-Research) have been used intensively in monitoring harbor porpoises (Phocoena phocoena) in the wild. However, the automated click-detection-mechanism of the T-POD leads to questions on the characteristics of the detection process. We undertook experiments with six captive harbor porpoises (four subadult males in one pool, two adult males in another) at the Dolfinarium Harderwijk (Netherlands). One T-POD was placed for over a week in each pool, while the behavior of the porpoises was logged by visual observation. Data were analyzed using the T-POD software. A total of 725 431 clicks in 30 090 trains were recorded with 32% of the trains classified as CET HI, 27% as CET LO, and 41% as DOUBTFUL. All three train classes differed significantly in all parameters, except for click duration. We conclude that T-PODs perform generally well in detecting click trains of harbor porpoises but that in any future study trains classified as being of lower probability should be investigated very carefully to avoid the risk of losing valuable information.
A local vector coding for high-quality voice analysis/synthesis
Authors: Ito Masashi , Yano Masafumi
Published: June 2005

Line-type spectrum is observed in frequency responses for voiced sound. The spectrum can be characterized by physical parameters: instantaneous amplitude, frequency, and phase for each component. It is difficult to estimate these parameters for natural utterances accurately by power spectrogram because the sound is usually unstationary. A new method, termed local vector coding (LVC), has been proposed to analyze these sounds. LVC assumes that the time-varying parameters for the input sound can be approximated by simple quadratic functions in a short analysis window. Utilizing the phase responses, LVC can estimate not only instantaneous amplitude and frequency for each component of the input but also their time derivatives. The validity of LVC method is examined by using naturally uttered voiced speech. The averaged estimation errors, defined by the differences between the input and resynthesized signals, are lower than 30 dB of the input energy. It indicates that LVC method is very useful for analyzing natural sounds. In addition, since the parameters of each component obtained by LVC method characterize the vowel quality, any kind of voice can be synthesized/transformed by changing each parameter independently, such as a voice of a male adult to a female voice.
THE BEHAVIORS OF THE MAGNETICALLY ALIGNED CLUSTER AND THE MAGNETORESISTANCE IN THE DOPED MANGANITE COMPOUNDS
Authors: REN SHI-WEI
Published: June 2005

By using a negative-magnetoresistivity scaling deduced from Mott's model, a specific scheme to quantitatively describe in detail the effects of the colossal magnetoresistivity (CMR) is proposed. The field-dependence of the magnetoresistance of the magnetic perovskite La 0.7 Ca 0.3 MnO 3 film is analyzed. The range of error for the value of the Curie temperature is reduced by our calculations. So, the Curie temperature can be determined more precisely. Through analyzing the variation of the field sensitivity (FS) with respect to some physics quantities, the main elements that influence the values of FS are revealed. Finally, the behaviors of the magnetically aligned clusters in the magnetic perovskite La 0.7 Ca 0.3 MnO 3 and Nd 0.52 Sr 0.48 MnO 3 film are investigated and analyzed.
THE DYNAMICS OF MULTILATERAL EXCHANGE
Authors: HAUSKEN KJELL , MOXNES JOHN F.
Published: June 2005

The article formulates a dynamic mathematical model where arbitrarily many players produce, consume, exchange, loan, and deposit arbitrarily many goods over time to maximize utility. Consuming goods constitutes a benefit, and producing, exporting, and loaning away goods constitute a cost. Utilities are benefits minus costs, which depend on the exchange ratios and bargaining functions. Three-way exchange occurs when one player acquires, through exchange, one good from another player with the sole purpose of using this good to exchange against the desired good from a third player. Such a triple handshake is not merely a set of double handshakes since the player assigns no interest to the first good in his benefit function. Cognitive and organization costs increase dramatically for higher order exchanges. An exchange theory accounting for media of exchange follows from simple generalization of two-way exchange. The examples of r-way exchange are the triangle trade between Africa, the USA, and England in the 17th and 18th centuries, the hypothetical hypercycle involving RNAs as players and enzymes as goods, and reaction–diffusion processes. The emergence of exchange, and the role of trading agents are discussed. We simulate an example where two-way exchange gives zero production and zero utility, while three-way exchange causes considerable production and positive utility. Maximum utility for each player is reached when exchanges of the same order as the number of players in society are allowed. The article merges micro theory and macro theory within the social, natural, and physical sciences.
Using Herbal Medicine as a Means of Prevention Experience During the SARS Crisis
Authors: Lau T. F. , Leung P. C. , Wong E. L. Y. , Fong C. , Cheng K. F. , Zhang S. C. , Lam C. W. K. , Wong V. , Choy K. M. , Ko W. M.
Published: June 2005

At the peak of the SARS epidemic in Hong Kong, hospital workers were under high risks of contraction of the infection. Herbal preparations had been used historically in China to treat influenza-like diseases. During the SARS outbreak, herbal preparations had been used jointly with standard modern treatment in China. As a means to protect the at-risk hospital workers, an innovative herbal formula was created and consumed by 3160 of them in two weeks. During the two weeks, symptoms and adverse effects were close monitored; 37 of them had their serum checked for immunological responses.

The results showed that none of the herb consumers contracted the infection, compared to 0.4% among the non-consumers. Adverse effects had been infrequent and mild. There were hardly any influenza-like symptoms and the quality of life improved. In the group who volunteered to have their immunological state checked, significant boosting effects were found. It was concluded that there might be a good indication for using suitable herbal preparations as a means of preventing influenza-like infection. The mode of preventive effect could be treatment of the infection at its very early stage instead of producing a period of higher immunological ability, as in the case of vaccination.
Anti-hypertensive Effect of Chunghyul-dan (Qingxue-dan) on Stroke Patients with Essential Hypertension
Authors: Yun Sang Pil , Jung Woo Sang , Park Seong Uk , Moon Sang Kwan , Ko Chang Nam , Cho Ki Ho , Kim Young Suk , Bae Hyung Sup
Published: June 2005

Hypertension is one of the modifiable risk factors for stroke. Lowering blood pressure is helpful for primary and secondary prevention of stroke. This study is aimed to assess the efficacy of Chunghyul-dan on stroke patients with stage 1 hypertension using 24 hours ambulatory blood pressure monitoring (24ABPM). Forty hospitalized stroke patients with stage 1 hypertension were included in the study and they were randomly assigned into two groups: group A was treated with Chunghyul-dan 1200 mg once a day for 2 weeks, while group B was not. Twelve subjects were dropped out because of unexpected early discharge or data errors, thus the remaining 28 subjects were included in the final analysis (15 in group A and 13 in group B). Blood pressure was monitored every 30 minutes for 24 hours at baseline and 2 weeks after medication. Blood pressure, pulse rate, trough/peak ratio (TPR) [the value calculated by dividing the blood pressure change at trough (22 to 24 hours after drug intake) by the change at peak (2 adjacent hours with a maximal blood pressure reduction between the second and eighth hour after drug intake)] and smoothness index (SI) (the value calculated as the ratio between the average of the 24 hours, treatment-induced blood pressure changes and its standard deviation) were compared to assess the efficacy of Chunghyul-dan. To assess the safety of Chunghyul-dan, any adverse effects during medication period were monitored. There was no significant difference in the baseline assessment between the two groups. Systolic blood pressure was lower in group A than in group B (141.37 ± 8.96 mmHg versus 132.28 ± 9.46 mmHg , P = 0.03), while diastolic blood pressure and pulse rate had no significant difference between the two groups. Systolic TPR and SI was 0.87 and 1.04 in group A, respectively. This suggests that Chunghyul-dan have anti-hypertensive effect on stroke patients with stage 1 hypertension.
Ginseng and Diabetes
Authors: Xie Jing-Tian , Mehendale Sangeeta , Yuan Chun-Su
Published: June 2005

Ginseng is a well-known medicinal plant used in traditional Oriental medicine. In recent decades, ginseng root has gained popularity as a dietary supplement in the United States. Ginseng has also been commonly used in Oriental medicine to treat diabetes-like conditions. The present review discusses the research on the anti-diabetic effects of ginseng and the possible mechanisms of its anti-diabetic actions.
Inhibitory Effects of Bezoar Bovis on Intimal Formation and Vascular Smooth Muscle Cell Proliferation in Rat
Authors: Mizuno Masaki , Chung Hwa-Jin , Maruyama Ikuro , Tani Tadato
Published: June 2005

Intimal formation of animal carotid arteries induced by balloon endothelial denudation has been considered to be an "accelerated atherosclerosis" model and used in primary screening methods to evaluate natural drugs and chemical candidates. The aim of the present study was to examine whether intimal formation is prevented by Bezoar Bovis (dried cattle gallbladder stones: Niuhuang in Chinese and Go-o in Japanese), which has been used to prevent heart palpitation in patients with hypertension. The intimal-to-medial area ratio in rat carotid arteries 7 days after balloon endothelial denudation was significantly reduced by oral administration of Bezoar Bovis. Bezoar Bovis also suppressed vascular smooth muscle cells (VSMCs) proliferation, which is thought to play important roles in the intimal formation after endothelial damage and also atherosclerosis resulting from long-term inappropriate lifestyle. The present findings suggest that Bezoar Bovis may be useful for preventing atherosclerosis and for protection against restenosis after percutaneous coronary intervention, for which effective reduction method is not currently available.
The Nephroprotective Effects of the Herbal Medicine Preparation, WH30+, on the Chemical-Induced Acute and Chronic Renal Failure in Rats
Authors: Ngai Heidi H. Y. , Sit Wai-Hung , Wan Jennifer M. F.
Published: June 2005

In this study, we evaluated the renal protective effects of a Chinese herbal preparation WH30+in male Wistar rats with glycerol-induced acute renal failure and adenine-induced chronic renal failure. WH30+is a Chinese herb preparation composed of Rheum Palmatum, Salvia Miltiorrhiza, Cordyceps Sinensis, Leonurus Sibiricus, Epihedium Macranthum, Radix Astragali, and Radix Codonopsis Pilosulae, which has been used to treat kidney deficiency in human. An acute renal failure and chronic renal failure rat model were introduced by glycerol injection (i.m.) and fed with adenine-excessive diet, respectively. WH30+was administered to rats at the dose of 50 mg/kg/day from 10 days before the diseases were induced until the rats were sacrificed. A reduction in body weight ( p < 0.01) was observed in rats with chronic renal failure, but there was no difference between treatment groups. However, the body weight of rats with acute renal failure without treatment was significantly lower than those treated with WH30+( p < 0.05). Overall, serum creatinine and urea nitrogen were elevated significantly ( p < 0.01) in renal failure rats compared to control. Treatment with WH30+improved both serum creatinine and urea nitrogen slightly in both models. The WH30+-treated rats with acute renal failure had significantly ( p < 0.05) greater creatinine clearance than those without treatment. The results of the study show that WH30+is more effective in the prevention of acute renal failure than chronic renal failure.
Novel Approach of Molecular Genetic Understanding of Iridology: Relationship Between Iris Constitution and Angiotensin Converting Enzyme Gene Polymorphism
Authors: Um Jae-Young , An Nyeon-Hyoung , Yang Gui-Bi , Lee Geon-Mok , Cho Ju-Jang , Cho Jae-Woon , Hwang Woo-Jun , Chae Han-Jung , Kim Hyung-Ryong , Hong Seung-Heon , Kim Hyung-Min
Published: June 2005

Iridology is the study of the iris of the eye to detect the conditions of the body and its organs, genetic strengths and weaknesses, etc. Although iridology is not widely used as a scientific tool for healthcare professionals to get to the source of people's health conditions, it has been used as a supplementary source to help the diagnosis of medical conditions by noting irregularities of the pigmentation in the iris among some Korean Oriental medical doctors. Angiotensin converting enzyme (ACE) gene polymorphism is one of the most well studied genetic markers of vascular disease. We investigated the relationship between iridological constitution and ACE polymorphism in hypertensives. We classified 87 hypertensives and 79 controls according to iris constitution and determined the ACE genotype of each individual. DD genotype was more prevalent in patients with a neurogenic constitution than in controls. This finding supports the hypothesis that D allele is a candidate gene for hypertension and demonstrates the association among ACE genotype, Korean hypertensives and iris constitution.
CONSISTENCY BETWEEN LIGHT-FRONT QUANTIZATION AND COVARIANTIZATION FOR ZERO MODES
Authors: SUZUKI ALFREDO T. , BENTÍN RICARDO
Published: June 2005

In the light-cone gauge choice for Abelian and non-Abelian gauge fields, the vector boson propagator carries in it an additional "spurious" or "unphysical" pole intrinsic to the choice requiring a careful mathematical treatment. Research in this field over the years has shown us that mathematical consistency only is not enough to guarantee physically meaningful results. Whatever the prescription invoked to handle such an object, it has to preserve causality in the process. On the other hand, the covariantization technique is a well-suited one to tackle gauge-dependent poles in the Feynman integrals, dispensing the use of ad hoc prescriptions. In this work we show that the covariantization technique in the light-cone gauge is a direct consequence of the canonical quantization of the theory.
APPLICATION OF A NEW HAMILTONIAN OF INTERACTION TO VORTICES STRUCTURE IN SUPERCONDUCTORS
Authors: DOLOCAN VOICU OCTAVIAN , DOLOCAN ANDREI , DOLOCAN VOICU
Published: June 2005

By using a new Hamiltonian,1 we have calculated the energy of one isolated vortex line and also the interaction energy between the vortices in superconductors. Also, we have calculated the elastic force constant in a vortex lattice. The interaction energy shows a minimum at a certain distance between the vortices. We analyze some aspects of this interaction. The obtained results are in good agreement with experimental data.
PERSISTENT CURRENT INDUCED BY BOTH AB AND AC EFFECTS IN A POLYACETYLENE RING
Authors: GAO Y.-F. , LI Z.-J. , LIANG J.-Q. , ZHANG G.-F.
Published: June 2005

We investigate the persistent current in a polyacetylene ring induced by axially symmetric, gauge potentials of both magnetic flux and static electric field using a modified SSH Hamiltonian for the polyacetylene chain. The AB and AC effects for an electron with spin are formulated simultaneously in a completely equal footing. It is shown that the gauge fields result in a Fröhlich-type superconductivity equivalent to the effect of a travelling lattice wave. The total energy as well as the persistent current density are shown to be periodic function of the total effective flux of the both gauge fields of AB and AC embraced by the polyacetylene ring.
A FAST TECHNIQUE FOR DERIVING FREQUENT STRUCTURED PATTERNS FROM BIOLOGICAL DATA SETS
Authors: TERRACINA GIORGIO
Published: June 2005

In the last years, the completion of the human genome sequencing showed a wide range of new challenging issues involving raw data analysis. In particular, the discovery of information implicitly encoded in biological sequences is assuming a prominent role in identifying genetic diseases and in deciphering biological mechanisms. This information is usually represented by patterns frequently occurring in the sequences. Because of biological observations, a specific class of patterns is becoming particularly interesting: frequent structured patterns. In this respect, it is biologically meaningful to look at both "exact" and "approximate" repetitions of pattens within the available sequences. This paper gives a contribution in this setting by providing algorithms which allow to discover frequent structured patterns, both in "exact" and "approximate" form, present in a collection of input biological sequences.
A HYBRID GENETIC ALGORITHM FOR THE MAXIMUM LIKELIHOOD ESTIMATION OF MODELS WITH MULTIPLE EQUILIBRIA: A FIRST REPORT
Authors: AGUIRREGABIRIA VICTOR , MIRA PEDRO
Published: June 2005

This paper presents a hybrid genetic algorithm to obtain maximum likelihood estimates of parameters in structural econometric models with multiple equilibria. The algorithm combines a pseudo maximum likelihood (PML) procedure with a genetic algorithm (GA). The GA searches globally over the large space of possible combinations of multiple equilibria in the data. The PML procedure avoids the computation of all the equilibria associated with every trial value of the structural parameters.
RETINOTECTAL MAPPING: New Insights from Molecular Genetics
Authors: Lemke Greg , Reber Michaël
Published: June 2005

The sensory and motor components of nervous systems are connected topographically and contain neural maps of the external world. The paradigm for such maps is the precisely ordered wiring of the output cells of the eye to their synaptic targets in the tectum of the midbrain. The retinotectal map is organized in development through the graded activity of Eph receptor tyrosine kinases and their ephrin ligands. These signaling proteins are arrayed in complementary expression gradients along the orthogonal axes of the retina and tectum, and provide both input and recipient cells with Cartesian coordinates that specify their location. Molecular genetic studies in the mouse indicate that these coordinates are interpreted in the context of neuronal competition for termination sites in the tectum. They further suggest that order in the retinotectal map is determined by ratiometric rather than absolute difference comparisons in Eph signaling along the temporal-nasal and dorsal-ventral axes of the eye.
THE OXIDATION OF NIAL: What Can We Learn from Ab Initio Calculations?
Authors: Finnis M.W. , Lozovoi A.Y. , Alavi A.
Published: June 2005

▪ Abstract  We review here the theory of the early stages of oxidation of the (110) surface of Ni1−x Alx, based on ab initio calculations using a plane-wave pseudopotential method. The clean surface and several oxidized surfaces have been investigated, with oxygen coverages up to 2ML of oxygen (1ML = 3 O atoms per 2 surface Al atoms). The theory to date is a description in terms of equilibrium thermodynamics, with a comparison of the free energies of several surfaces of different composition, implemented at the atomic scale. Three environmental parameters are singled out as control variables in this treatment, namely the alloy composition x (assumed to be near 0.5), the temperature T and the partial pressure of oxygen pO2. With certain reasonable approximations an analytic formula for the surface energy σ is derived in terms of these variables and some constants that are calculated ab initio together with others that are derived from experimental thermodynamic tables. At oxygen pressures just above the threshold for bulk oxidation of NiAl, the calculations explain the observed formation of a thin film of alumina in place of NiAl surface layers, with the consequent dissolution of Ni into the bulk. Ab initio calculations illustrate how the energetics of supplying Al to the surface depends on bulk stoichiometry, which alters the relative stability of different surface oxidation states so as to favour oxidation more if the alloy is Al-rich than if it is Ni-rich.
POROUS ALUMINOPHOSPHATES :From Molecular Sieves to Designed Acid Catalysts
Authors: Pastore H.O. , Coluccia S. , Marchese L.
Published: June 2005

▪ Abstract  This review covers the synthesis, characterization, and physico-chemical properties of microporous and mesoporous aluminophosphates and silicoaluminophosphates molecular sieves. Particular emphasis is given to the materials that have found applications as acid catalysts. We consider the evolution of the synthesis procedures from the first discoveries to the current methodologies and give perspectives for new possible synthesis strategies. Emphasis is given to the use of specially prepared precursors/reactants designed for the use as molecular sieves. Experimental (especially MAS-NMR and FTIR spectroscopy) and theoretical approaches to the description of the Si insertion into the ALPO framework and to the acidic properties of SAPOs and MeAPSOs materials are discussed.
Corticosteroid-regulated genes in rat kidney: mining time series array data
Authors: Almon Richard R. , Lai William , DuBois Debra C. , Jusko William J.
Published: June 2005

Kidney is a major target for adverse effects associated with corticosteroids. A microarray dataset was generated to examine changes in gene expression in rat kidney in response to methylprednisolone. Four control and 48 drug-treated animals were killed at 16 times after drug administration. Kidney RNA was used to query 52 individual Affymetrix chips, generating data for 15,967 different probe sets for each chip. Mining techniques applicable to time series data that identify drug-regulated changes in gene expression were applied. Four sequential filters eliminated probe sets that were not expressed in the tissue, not regulated by drug, or did not meet defined quality control standards. These filters eliminated 14,890 probe sets (94%) from further consideration. Application of judiciously chosen filters is an effective tool for data mining of time series datasets. The remaining data can then be further analyzed by clustering and mathematical modeling. Initial analysis of this filtered dataset identified a group of genes whose pattern of regulation was highly correlated with prototype corticosteroid enhanced genes. Twenty genes in this group, as well as selected genes exhibiting either downregulation or no regulation, were analyzed for 5′ GRE half-sites conserved across species. In general, the results support the hypothesis that the existence of conserved DNA binding sites can serve as an important adjunct to purely analytic approaches to clustering genes into groups with common mechanisms of regulation. This dataset, as well as similar datasets on liver and muscle, are available online in a format amenable to further analysis by others.
Adenine nucleotide regulation in pancreatic β-cells: modeling of ATP/ADP-Ca2+interactions
Authors: Fridlyand Leonid E. , Ma Li , Philipson Louis H.
Published: June 2005

Glucose metabolism stimulates insulin secretion in pancreatic β-cells. A consequence of metabolism is an increase in the ratio of ATP to ADP ([ATP]/[ADP]) that contributes to depolarization of the plasma membrane via inhibition of ATP-sensitive K+(KATP) channels. The subsequent activation of calcium channels and increased intracellular calcium leads to insulin exocytosis. Here we evaluate new data and review the literature on nucleotide pool regulation to determine the utility and predictive value of a new mathematical model of ion and metabolic flux regulation in β-cells. The model relates glucose consumption, nucleotide pool concentration, respiration, Ca2+flux, and KATPchannel activity. The results support the hypothesis that β-cells maintain a relatively high [ATP]/[ADP] value even in low glucose and that dramatically decreased free ADP with only modestly increased ATP follows from glucose metabolism. We suggest that the mechanism in β-cells that leads to this result can simply involve keeping the total adenine nucleotide concentration unchanged during a glucose elevation if a high [ATP]/[ADP] ratio exits even at low glucose levels. Furthermore, modeling shows that independent glucose-induced oscillations of intracellular calcium can lead to slow oscillations in nucleotide concentrations, further predicting an influence of calcium flux on other metabolic oscillations. The results demonstrate the utility of comprehensive mathematical modeling in understanding the ramifications of potential defects in β-cell function in diabetes.
Posttranscriptional control of aquaporin-2 abundance by vasopressin in renal collecting duct principal cells
Authors: Hasler Udo , Nielsen Søren , Féraille Eric , Martin Pierre-Yves
Published: June 2005

Prevailing expression levels of aquaporin-2 (AQP2) mRNA play a major role in regulating AQP2 protein abundance. Here, we investigated whether AQP2 protein abundance is regulated at a posttranscriptional level as well. The expression levels of both AQP2 mRNA and protein increase in response to arginine vasopressin (AVP) in a concentration- and time-dependent manner in cultured immortalized mouse collecting duct principal cells (mpkCCDcl4cells). AVP washout from the medium of AVP-pretreated cells revealed that AQP2 mRNA expression progressively decreased over time, whereas AQP2 protein abundance first increased immediately after AVP washout and then gradually decreased over time. Inversely, increasing AVP concentration led to a time-dependent increase of AQP2 mRNA, whereas AQP2 protein abundance first decreased immediately after AVP supplementation and then gradually increased over time. These transient effects arose from altered V2-receptor activity because they could be abolished by SR-121463B, a specific V2-receptor antagonist. Although cycloheximide administration had no effect on transient alterations of AQP2 protein content, these effects were attenuated by administration of chloroquine, a lysosomal inhibitor, or lactacystin, a proteasomal inhibitor. Short-term inhibition of PKA activity significantly increased AQP2 protein abundance and blunted the transient alterations of AQP2 protein content induced by AVP washout and supplementation. In addition, phosphorylated AQP2 abundance increased immediately after AVP supplementation. These results indicate that in response to AVP AQP2 protein abundance in collecting duct principal cells is principally influenced by AQP2 mRNA content but is additionally regulated by PKA-dependent negative feedback acting on AQP2 protein degradation.
Prostaglandin E2EP2 and EP4 receptor activation mediates cAMP-dependent hyperpolarization and exocytosis of renin in juxtaglomerular cells
Authors: Friis Ulla G. , Stubbe Jane , Uhrenholt Torben R. , Svenningsen Per , Nüsing Rolf M. , Skøtt Ole , Jensen Boye L.
Published: June 2005

PGE2and PGI2stimulate renin secretion and cAMP accumulation in juxtaglomerular granular (JG) cells. We addressed, at the single-cell level, the receptor subtypes and intracellular transduction mechanisms involved. Patch clamp was used to determine cell capacitance ( Cm), current, and membrane voltage in response to PGE2, EP2 and EP4 receptor agonists, and an IP receptor agonist. PGE2(0.1 μmol/l) increased Cmsignificantly, and the increase was abolished by intracellular application of the protein kinase A antagonist Rp-8-CPT-cAMPS. EP2-selective ligands butaprost (1 μmol/l), AE1–259-01 (1 nmol/l), EP4-selective agonist AE1–329 (1 nmol/l), and IP agonist iloprost (1 μmol/l) significantly increased Cmmediated by PKA. The EP4 antagonist AE3–208 (10 nmol/l) blocked the effect of EP4 agonist but did not alter the response to PGE2. Application of both EP4 antagonist and EP2-antagonist AH-6809 abolished the effects of PGE2on Cmand current. EP2 and EP4 ligands stimulated cAMP formation in JG cells. PGE2rapidly stimulated renin secretion from superfused JG cells and diminished the membrane-adjacent granule pool as determined by confocal microscopy. The membrane potential hyperpolarized significantly after PGE2, butaprost, AE1–329 and AE1–259 and outward current was augmented in a PKA-dependent fashion. PGE2-stimulated outward current, but not Cmchange, was abolished by the BKCachannel inhibitor iberiotoxin (300 nmol/l). EP2 and EP4 mRNA was detected in sampled JG cells, and the preglomerular and glomerular vasculature was immunopositive for EP4. Thus IP, EP2, and EP4 receptors are associated with JG cells, and their activation leads to rapid PKA-mediated exocytotic fusion and release of renin granules.
Fidelity of the Ensemble Code for Visual Motion in Primate Retina
Authors: Frechette E. S. , Sher A. , Grivich M. I. , Petrusca D. , Litke A. M. , Chichilnisky E. J.
Published: June 2005

Sensory experience typically depends on the ensemble activity of hundreds or thousands of neurons, but little is known about how populations of neurons faithfully encode behaviorally important sensory information. We examined how precisely speed of movement is encoded in the population activity of magnocellular-projecting parasol retinal ganglion cells (RGCs) in macaque monkey retina. Multi-electrode recordings were used to measure the activity of ∼100 parasol RGCs simultaneously in isolated retinas stimulated with moving bars. To examine how faithfully the retina signals motion, stimulus speed was estimated directly from recorded RGC responses using an optimized algorithm that resembles models of motion sensing in the brain. RGC population activity encoded speed with a precision of ∼1%. The elementary motion signal was conveyed in ∼10 ms, comparable to the interspike interval. Temporal structure in spike trains provided more precise speed estimates than time-varying firing rates. Correlated activity between RGCs had little effect on speed estimates. The spatial dispersion of RGC receptive fields along the axis of motion influenced speed estimates more strongly than along the orthogonal direction, as predicted by a simple model based on RGC response time variability and optimal pooling. on and off cells encoded speed with similar and statistically independent variability. Simulation of downstream speed estimation using populations of speed-tuned units showed that peak (winner take all) readout provided more precise speed estimates than centroid (vector average) readout. These findings reveal how faithfully the retinal population code conveys information about stimulus speed and the consequences for motion sensing in the brain.
Myocardial Substrate Metabolism in the Normal and Failing Heart
Authors: Stanley William C. , Recchia Fabio A. , Lopaschuk Gary D.
Published: June 2005

The alterations in myocardial energy substrate metabolism that occur in heart failure, and the causes and consequences of these abnormalities, are poorly understood. There is evidence to suggest that impaired substrate metabolism contributes to contractile dysfunction and to the progressive left ventricular remodeling that are characteristic of the heart failure state. The general concept that has recently emerged is that myocardial substrate selection is relatively normal during the early stages of heart failure; however, in the advanced stages there is a downregulation in fatty acid oxidation, increased glycolysis and glucose oxidation, reduced respiratory chain activity, and an impaired reserve for mitochondrial oxidative flux. This review discusses 1) the metabolic changes that occur in chronic heart failure, with emphasis on the mechanisms that regulate the changes in the expression of metabolic genes and the function of metabolic pathways; 2) the consequences of these metabolic changes on cardiac function; 3) the role of changes in myocardial substrate metabolism on ventricular remodeling and disease progression; and 4) the therapeutic potential of acute and long-term manipulation of cardiac substrate metabolism in heart failure.
Invertebrate Muscles: Muscle Specific Genes and Proteins
Authors: Hooper Scott L. , Thuma Jeffrey B.
Published: June 2005

This is the first of a projected series of canonic reviews covering all invertebrate muscle literature prior to 2005 and covers muscle genes and proteins except those involved in excitation-contraction coupling (e.g., the ryanodine receptor) and those forming ligand- and voltage-dependent channels. Two themes are of primary importance. The first is the evolutionary antiquity of muscle proteins. Actin, myosin, and tropomyosin (at least, the presence of other muscle proteins in these organisms has not been examined) exist in muscle-like cells in Radiata, and almost all muscle proteins are present across Bilateria, implying that the first Bilaterian had a complete, or near-complete, complement of present-day muscle proteins. The second is the extraordinary diversity of protein isoforms and genetic mechanisms for producing them. This rich diversity suggests that studying invertebrate muscle proteins and genes can be usefully applied to resolve phylogenetic relationships and to understand protein assembly coevolution. Fully achieving these goals, however, will require examination of a much broader range of species than has been heretofore performed.
The Retinal Pigment Epithelium in Visual Function
Authors: Strauss Olaf
Published: June 2005

Located between vessels of the choriocapillaris and light-sensitive outer segments of the photoreceptors, the retinal pigment epithelium (RPE) closely interacts with photoreceptors in the maintenance of visual function. Increasing knowledge of the multiple functions performed by the RPE improved the understanding of many diseases leading to blindness. This review summarizes the current knowledge of RPE functions and describes how failure of these functions causes loss of visual function. Mutations in genes that are expressed in the RPE can lead to photoreceptor degeneration. On the other hand, mutations in genes expressed in photoreceptors can lead to degenerations of the RPE. Thus both tissues can be regarded as a functional unit where both interacting partners depend on each other.
Thin and Strong! The Bioengineering Dilemma in the Structural and Functional Design of the Blood-Gas Barrier
Authors: Maina John N. , West John B.
Published: June 2005

In gas exchangers, the tissue barrier, the partition that separates the respiratory media (water/air and hemolymph/blood), is exceptional for its remarkable thinness, striking strength, and vast surface area. These properties formed to meet conflicting roles: thinness was essential for efficient flux of oxygen by passive diffusion, and strength was crucial for maintaining structural integrity. What we have designated as “three-ply” or “laminated tripartite” architecture of the barrier appeared very early in the evolution of the vertebrate gas exchanger. The design is conspicuous in the water-blood barrier of the fish gills through the lungs of air-breathing vertebrates, where the plan first appeared in lungfishes (Dipnoi) some 400 million years ago. The similarity of the structural design of the barrier in respiratory organs of animals that remarkably differ phylogenetically, behaviorally, and ecologically shows that the construction has been highly conserved both vertically and horizontally, i.e., along and across the evolutionary continuum. It is conceivable that the blueprint may have been the only practical construction that could simultaneously grant satisfactory strength and promote gas exchange. In view of the very narrow allometric range of the thickness of the blood-gas barrier in the lungs of different-sized vertebrate groups, the measurement has seemingly been optimized. There is convincing, though indirect, evidence that the extracellular matrix and particularly the type IV collagen in the lamina densa of the basement membrane is the main stress-bearing component of the blood-gas barrier. Under extreme conditions of operation and in some disease states, the barrier fails with serious consequences. The lamina densa which in many parts of the blood-gas barrier is <50 nm thin is a lifeline in the true sense of the word.
Grenzen der Sentinel-Lymphknotenbiopsie beim Mammakarzinom
Authors: Fehr Mathias K.
Published: June 2005

Die Sentinel-Lymphknotenbiopsie gilt als etablierte Methode bei unifokalem, invasivem Mammakarzinom mit klinisch negativer Axilla. Randomisierte, grosse Studien konnten die niedrigere Morbidität verglichen mit der axillären Lymphonodektomie belegen und die Falsch-negativ-Rate etablieren (7–9, 7%). Mehrere technische Details der Methode sowie einzelne Kontraindikationen sind jedoch nach wie vor umstritten. Bis zu einer Tumorgrösse von 2 cm gilt die Methode bei unifokalen, klinisch nodalnegativen Tumoren als Methode der Wahl. Es gibt jedoch zunehmende Beobachtungen, dass die Sentinel-Lymphknotenbiopsie auch bei grösseren und multifokalen Tumoren akkurat ist. Nach neoadjuvanter Chemotherapie kann die Methode jedoch nicht empfohlen werden.
Interpersonal Aspects of Personality Disorders in Opioid-Dependent Patients: The Convergence of the ICL-R and the SIDP-IV
Authors: Damen Katinka F.M. , DeJong Cor A.J. , Nass Germa C.M. , VanderStaak Cees P.F. , Breteler Marinus H.M.
Published: June 2005

This study aims to establish the convergence of the empirically based Diagnostic Statistical Manual (DSM)- and theory-based interpersonal behavioral approaches to personality, in opioid-dependent patients (n = 110), with the use of the Structured Interview for DSM-IV Personality [Pfohl et al.: Structured Interview for DSM-IV PD. Iowa City, UICM, 1995] and the Interpersonal Checklist-Revised (ICL-R) [DeJong and VandenBrink: ICL-R. St. Oedenrode/NL, Novadic, 1998]. As hypothesized, based on prior research, we found the two approaches to be complementary rather than interchangeable. However, some overlap was found between the SIDP-IV dimensions and the ICL-R, mainly with rebellious/distrustful, reserved/silent and masochistic/self-effacing styles. Results indicate that drug dependence in itself is not a predictor of interpersonal style, while personality pathology is. Patients with a personality disorder (PD) perceive themselves as hostile and submissive, while patients without a PD view themselves as friendly and controlling. The SIDP-IV seems informative in classifying PDs, in addition guidelines for behavioral change, in addicted patients, were provided based on the ICL-R.