bluuebunny/crossref_metadata_2025 huggingface dataset:
A scanning calorimeter for thermal analysis of biological materials
Authors: M B Smith  , S J Rose
Published: July 2002

A differential adiabatic calorimeter having cells designed for handling solid or liquid samples of variable volume is described. Good resolution may be achieved at scanning rates of 4-20 degrees C h-1with a sensitivity such that a thermal effect of 0.05 cal degrees C-1can be measured with a precision of 5%. A simple modification allows use of the instrument as a differential thermal analyzer.
Real hypersurfaces of 𝐶𝑃ⁿ with non-negative Ricci curvature
Authors: Bejancu Aurel , Deshmukh Sharief
Published: July 2002

We prove the non-existence of Levi flat compact real hypersurfaces without boundary in

C

P
n

,
n
>
1

CP^n,n>1

, with non-negative totally real Ricci curvature.
𝐶¹ Connecting Lemmas
Authors: Wen Lan , Xia Zhihong
Published: July 2002

Like the closing lemma, the connecting lemma is of fundamental importance in dynamical systems. Hayashi recently proved the

C
1

C^1

connecting lemma for stable and unstable manifolds of a hyperbolic invariant set. In this paper, we prove several very general

C
1

C^1

connecting lemmas. We simplify Hayashi’s proof and extend the results to more general cases.
Asymptotic linear bounds for the Castelnuovo-Mumford regularity
Authors: Herzog Jürgen , Hoa Lê , Trung Ngô
Published: July 2002

We prove asymptotic linear bounds for the Castelnuovo-Mumford regularity of certain filtrations of homogeneous ideals whose Rees algebras need not be Noetherian.
Export from Pericentriolar Endocytic Recycling Compartment to Cell Surface Depends on Stable, Detyrosinated (Glu) Microtubules and Kinesin
Authors: Lin Sharron X. , Gundersen Gregg G. , Maxfield Frederick R.
Published: July 2002

A significant fraction of internalized transferrin (Tf) concentrates in the endocytic recycling compartment (ERC), which is near the microtubule-organizing center in many cell types. Tf then recycles back to the cell surface. The mechanisms controlling the localization, morphology, and function of the ERC are not fully understood. We examined the relationship of Tf trafficking with microtubules (MTs), specifically the subset of stable, detyrosinated Glu MTs. We found some correlation between the level of stable Glu MTs and the distribution of the ERC; in cells with low levels of Glu MTs concentrated near to the centriole, the ERC was often tightly clustered, whereas in cells with higher levels of Glu MTs throughout the cell, the ERC was more dispersed. The clustered ERC in Chinese hamster ovary cells became dispersed when the level of Glu MTs was increased with taxol treatment. Furthermore, in a temperature-sensitive Chinese hamster ovary cell line (B104-5), the cells had more Glu MTs when the ERC became dispersed at elevated temperature. Microinjecting purified anti-Glu tubulin antibody into B104-5 cells at elevated temperature induced the redistribution of the ERC to a tight cluster. Microinjection of anti-Glu tubulin antibody slowed recycling of Tf to the cell surface without affecting Tf internalization or delivery to the ERC. Similar inhibition of Tf recycling was caused by microinjecting anti-kinesin antibody. These results suggest that stable Glu MTs and kinesin play a role in the organization of the ERC and in facilitating movement of vesicles from the ERC to the cell surface.
The language of RNA: a formal grammar that includes pseudoknots
Authors: Rivas Elena , Eddy Sean R.
Published: July 2002

Motivation: In a previous paper, we presented a polynomial time dynamic programming algorithm for predicting optimal RNA secondary structure including pseudoknots. However, a formal grammatical representation for RNA secondary structure with pseudoknots was still lacking.

Results: Here we show a one-to-one correspondence between that algorithm and a formal transformational grammar. This grammar class encompasses the context-free grammars and goes beyond to generate pseudoknotted structures. The pseudoknot grammar avoids the use of general context-sensitive rules by introducing a small number of auxiliary symbols used to reorder the strings generated by an otherwise context-free grammar. This formal representation of the residue correlations in RNA structure is important because it means we can build full probabilistic models of RNA secondary structure, including pseudoknots, and use them to optimally parse sequences in polynomial time.

Contact: eddy@genetics.wustl.edu
Extending traditional query-based integration approaches for
functional characterization of post-genomic data
Authors: Eckman Barbara A. , Kosky Anthony S. , Laroco, Jr Leonardo A.
Published: July 2002

Motivation: To identify and characterize regions of functional interest in genomic sequence requires full, flexible query access to an integrated, up-to-date view of all related information, irrespective of where it is stored (within an organization or across the Internet) and its format (traditional database, flat file, web site, results of runtime analysis). Wide-ranging multi-source queries often return unmanageably large result sets, requiring non-traditional approaches to exclude extraneous data.

Results: Target Informatics Net (TINet) is a readily extensible data integration system developed at GlaxoSmith- Kline (GSK), based on the Object-Protocol Model (OPM) multidatabase middleware system of Gene Logic Inc. Data sources currently integrated include: the Mouse Genome Database (MGD) and Gene Expression Database (GXD), GenBank, SwissProt, PubMed, GeneCards, the results of runtime BLAST and PROSITE searches, and GSK proprietary relational databases. Special-purpose class methods used to filter and augment query results include regular expression pattern-matching over BLAST HSP alignments and retrieving partial sequences derived from primary structure annotations. All data sources and methods are accessible through an SQL-like query language or a GUI, so that when new investigations arise no additional programming beyond query specification is required. The power and flexibility of this approach are illustrated in such integrated queries as: (1) ‘find homologs in genomic sequence to all novel genes cloned and reported in the scientific literature within the past three months that are linked to the MeSH term ‘neoplasms”; (2) ‘using a neuropeptide precursor query sequence, return only HSPs where the target genomic sequences conserve the G[KR][KR] motif at the appropriate points in the HSP alignment’; and (3) ‘of the human genomic sequences annotated with exon boundaries in GenBank, return only those with valid putative donor/acceptor sites and start/stop codons’.

Availability: Freely available to non-profit educational and research institutions. Usage by commercial entities requires a license agreement.

Contact: barbara_eckman@sbphrd.com

* To whom correspondence should be addressed.
The role of differential activation of p38‐mitogen‐activated protein kinase in preconditioned ventricular myocytes
Authors: Saurin Adrian T. , Martin Jody L. , Heads Richard J. , Foley Claire , Mockridge James W. , Wright Matt J. , Wang Yibin , Marber Michael S.
Published: July 2002

Activation of protein kinase C (PKC) and more recently mitogen‐activated protein kinases (MAPKs) have been associated with the cardioprotective effect of ischemic preconditioning. We examined the interplay between these kinases in a characterized model of ischemic preconditioning in cultured rat neonatal ventricular cardiocytes where ectopic expression of active PKC‐δ results in protection. Two members of the MAPK family, p38 and p42/44, were activated transiently during preconditioning by brief simulated ischemia/reoxygenation. Overexpression of active PKC‐δ, rather than augmenting, completely abolished this activation. We therefore determined whether a similar process occurred during lethal prolonged simulated ischemia. In contrast to ischemia, brief, lethal‐simulated ischemia activated only p38 (2.8±0.45 vs. basal, P<0.01), which was attenuated by expression of active PKC‐δ or by preconditioning (0.48 ±0.1 vs. ischemia, P<0.01). To determine whether reduced p38 activation was the cause or an effect of protection, we used SB203580, a p38 inhibitor. SB203580 reduced ischemic injury (CK release 38.0± 3.1%, LDH release 77.3±4.0%, and MTT bioreduction 127.1 ±4.8% of control, n=20, P<0.05). To determine whether p38 activation was isoform selective, myocytes were infected with adenoviruses encoding wild‐type p38a or p38β. Transfected p38a and β show differential activation (P<0.001) during sustained simulated ischemia, with p38a remaining activated (1.48±0.36 vs. basal) but p38β deactivated (0.36± 0.1 vs. basal, P<0.01). Prior preconditioning prevented the activation of p38a (0.65±0.11 vs. ischemia, P<0.05). Moreover, cells expressing a dominant negative p38α, which prevented ischemic p38 activation, were resistant to lethal simulated ischemia (CK release 82.9±3.9% and MTT bioreduction 130.2±6.5% of control, n=8, P<0.05). Thus, inhibition of p38α activation during ischemia reduces injury and may contribute to preconditioning‐induced cardioprotection in this model.—Saurin, A. T., Martin, J. L., Heads, R. J., Foley, C., Mockridge, J. W., Wright, M. J., Wang, Y., Marber, M. S. The role of differential activation of p38‐mitogen‐activated protein kinase in preconditioned ventricular myocytes. FASEB J. 14, 2237–2246 (2000)
DNA polymerase mu, a candidate hypermutase?
Authors: Ruiz José F. , Domínguez Orlando , Laín de Lera Teresa , García–Díaz Miguel , Bernad Antonio , Blanco Luis
Published: July 2002

A novel DNA polymerase (Pol μ) has been recently identified in human cells. The amino–acid sequence of Pol μ is 42% identical to that of terminal deoxynucleotidyl transferase (TdT), a DNA–independent DNA polymerase that contributes to antigen–receptor diversity. In this paper we review the evidence supporting the role of Pol μ in somatic hypermutation of immunoglobulin genes, a T–dependent process that selectively occurs at germinal centres: (i) preferential expression in secondary lymphoid organs; (ii) expression associated to developing germinal centres; and (iii) very low base discrimination during DNA–dependent DNA polymerization by Pol μ, a mutator phenotype enormously accentuated by the presence of activating Mn2+ions. Moreover, its similarity to TdT, together with extrapolation to the crystal structure of DNA polymerase beta complexed (Pol β) with DNA, allows us to discuss the structural basis for the unprecedented error proneness of Pol μ, and to predict that Pol μ is structurally well suited to participate also in DNA end–filling steps occurring both during V(D)J recombination and repair of DNA double–strand breaks that are processed by non–homologous end–joining.
Elastin: a representative ideal protein elastomer
Authors: Urry D. W. , Hugel T. , Seitz M. , Gaub H. E. , Sheiba L. , Dea J. , Xu J. , Parker T.
Published: July 2002

During the last half century, identification of an ideal (predominantly entropic) protein elastomer was generally thought to require that the ideal protein elastomer be a random chain network. Here, we report two new sets of data and review previous data. The first set of new data utilizes atomic force microscopy to report single-chain force-extension curves for (GVGVP)
251
and (GVGIP)
260
, and provides evidence for single-chain ideal elasticity. The second class of new data provides a direct contrast between low-frequency sound absorption (0.1-10 kHz) exhibited by random-chain network elastomers and by elastin protein-based polymers. Earlier composition, dielectric relaxation (1-1000 MHz), thermoelasticity, molecular mechanics and dynamics calculations and thermodynamic and statistical mechanical analyses are presented, that combine with the new data to contrast with random-chain network rubbers and to detail the presence of regular non-random structural elements of the elastin-based systems that lose entropic elastomeric force upon thermal denaturation. The data and analyses affirm an earlier contrary argument that components of elastin, the elastic protein of the mammalian elastic fibre, and purified elastin fibre itself contain dynamic, non-random, regularly repeating structures that exhibit dominantly entropic elasticity by means of a damping of internal chain dynamics on extension.
Intracellular trafficking by Star regulates cleavage of the Drosophila EGF receptor ligand Spitz
Authors: Tsruya Rachel , Schlesinger Ayelet , Reich Aderet , Gabay Limor , Sapir Amir , Shilo Ben-Zion
Published: July 2002

Spitz (Spi) is a TGFα homolog that is a cardinal ligand for theDrosophila EGF receptor throughout development. Cleavage of the ubiquitously expressed transmembrane form of Spi (mSpi) precedes EGF receptor activation. We show that the Star and Rhomboid (Rho) proteins are necessary for Spi cleavage in Drosophila cells. Complexes between the Spi and Star proteins, as well as between the Star and Rho proteins were identified, but no Spi–Star–Rho triple complex was detected. This observation suggests a sequential activity of Star and Rho in mSpi processing. The interactions between Spi and Star regulate the intracellular trafficking of Spi. The Spi precursor is retained in the periphery of the nucleus. Coexpression of Star promotes translocation of Spi to a compartment where Rho is present both in cells and in embryos. A Star deletion construct that maintains binding to Spi and Rho, but is unable to facilitate Spi translocation, lost biological activity. These results underscore the importance of regulated intracellular trafficking in processing of a TGFα family ligand.
Delivery of intensity‐modulated radiation therapy with a conventional multileaf collimator: Comparison of dynamic and segmental methods
Authors: Chui Chen‐Shou , Chan Maria F. , Yorke Ellen , Spirou Spiridon , Ling C. Clifton
Published: July 2002

Intensity‐modulated radiation therapy (IMRT) can be delivered with a conventional multileaf collimator (MLC), either in dynamic mode (DMLC) or in segmental mode (SMLC, also known as “step‐and‐shoot”). The advantage of DMLC is its ability to deliver the desired intensity profile produced by inverse planning with a high degree of fidelity. The SMLC method, on the other hand, resembles treatment with multiple static fields, and can be more easily verified. However, the use of SMLC requires that the desired profile be approximated by discrete levels of intensity, which may lead to degradation in the delivered dose distribution. Clearly, the results of SMLC delivery depend on the number of levels and the spatial resolution of the intensity distribution. In this work, we compare the DMLC method and the SMLC method employing different numbers of levels and different spatial resolutions. Three disease sites were studied: prostate, nasopharynx, and breast, with three cases for each. In general, a 5‐ to 10‐level SMLC plan produced results comparable to that from a DMLC plan. The target coverage is improved by increasing the number of levels while critical organs are better protected with finer spatial resolutions. The beam‐on‐time (MUs) requirement for SMLC was approximately 20% less than DMLC, but the delivery time (in minutes) was about twice as long. Thus, the choice depends on many factors including machine capability, quality assurance, target coverage, critical organ protection, beam‐on‐time, delivery time, and other clinical considerations.
Empirical investigation of the signal performance of a high‐resolution, indirect detection, active matrix flat‐panel imager (AMFPI) for fluoroscopic and radiographic operation
Authors: Antonuk L. E. , El‐Mohri Y. , Siewerdsen J. H. , Yorkston J. , Huang W. , Scarpine V. E. , Street R. A.
Published: July 2002

Signal properties of the first large‐area, high resolution, active matrix, flat‐panel imager are reported. The imager is based on an array of 1536×1920 pixels with a pixel‐to‐pixel pitch of 127 μm. Each pixel consists of a discrete amorphous silicon n‐i‐p photodiode coupled to an amorphous silicon thin‐film transistor. The imager detects incident x rays indirectly by means of an intensifying screen placed over the array. External acquisition electronics send control signals to the array and process analog imaging signals from the pixels. Considerations for operation of the imager in both fluoroscopic and radiographic modes are detailed and empirical signal performance data are presented with an emphasis on exploring similarities and differences between the two modes. Measurements which characterize the performance of the imager were performed as a function of operational parameters in the absence or presence of illumination from a light‐emitting diode or x rays. These measurements include characterization of the drift and magnitude of the pixel dark signal, the size of the pixel switching transient, the temporal behavior of pixel sampling and the implied maximum frame rate, the dependence of relative pixel efficiency and pixel response on photodiode reverse bias voltage and operational mode, the degree of linearity of pixel response, and the trapping and release of charge from metastable states in the photodiodes. In addition, x‐ray sensitivity as a function of energy for a variety of phosphor screens for both fluoroscopic and radiographic operation is reported. Example images of a line‐pair pattern and an anthropomorphic phantom in each mode are presented along with a radiographic image of a human hand. General and specific improvements in imager design are described and anticipated developments are discussed. This represents the first systematic investigation of the operation and properties in both radiographic and fluoroscopic modes of an imager incorporating such an array.
Calculated mammographic spectra confirmed with attenuation curves for molybdenum, rhodium, and tungsten targets
Authors: Blough Melissa M. , Waggener Robert G. , Payne William H. , Terry James A.
Published: July 2002

A model for calculating mammographic spectra independent of measured data and fitting parameters is presented. This model is based on first principles. Spectra were calculated using various target and filter combinations such as molybdenum/molybdenum, molybdenum/rhodium, rhodium/rhodium, and tungsten/aluminum. Once the spectra were calculated, attenuation curves were calculated and compared to measured attenuation curves. The attenuation curves were calculated and measured using aluminum alloy 1100 or high purity aluminum filtration. Percent differences were computed between the measured and calculated attenuation curves resulting in an average of 5.21% difference for tungsten/aluminum, 2.26% for molybdenum/molybdenum, 3.35% for rhodium/rhodium, and 3.18% for molybdenum/rhodium. Calculated spectra were also compared to measured spectra from the Food and Drug Administration [Fewell and Shuping, Handbook of Mammographic X‐ray Spectra (U.S. Government Printing Office, Washington, D.C., 1979)] and a comparison will also be presented.
Design and evaluation of an LSO PET detector for breast cancer imaging
Authors: Doshi Niraj K. , Shao Yiping , Silverman Robert W. , Cherry Simon R.
Published: July 2002

Functional imaging with positron emission tomography (PET) may be a promising technique in conjunction with x‐ray mammography for breast cancer patient management. Conventional whole body PET scanners provide metabolic images of breast cancer patients with several shortcomings related to the general‐purpose nature of these systems. In whole body scanners, the detectors are typically 20–30 cm away from the breast or axilla, reducing sensitivity, and these scanners have relatively large detector elements (> 4 mm), limiting spatial resolution. Dedicated PET systems for breast imaging aim to overcome these limitations and improve the overall diagnostic quality of the images by bringing the detectors closer to the area to be imaged, thereby improving sensitivity, and by using smaller detector elements to improve the spatial resolution. We have designed and developed a modular PET detector that is composed of a 9×9 array of 3×3×20 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to an optical fiber taper, which in turn is coupled to a Hamamatsu R5900‐C8 position‐sensitive photomultiplier tube. These detectors can be tiled together without gaps to construct large area detector arrays to form a dedicated PET breast cancer imaging system. Two complete detector modules have been built and tested. All detector elements are clearly visualized upon flood irradiation of the module. The intrinsic spatial resolution (full‐width at half‐maximum) was measured to be 2.26 mm (range 1.8–2.6 mm). The average energy resolution was 19.5% (range 17%–24%) at 511 keV. The coincidence time resolution was measured to be 2.4 ns. The detector efficiency for 511 keV gamma rays was 53% using a 350 keV energy threshold. These promising results support the feasibility of developing a high resolution, high sensitivity dedicated PET scanner for breast cancer applications.
Teaching time-series analysis. I. Finite Fourier analysis of ocean waves
Authors: Whitford Dennis J. , Vieira Mario E. C. , Waters Jennifer K.
Published: July 2002

The introduction of students to methods of time-series analysis is a pedagogical challenge, since the availability of easily manipulated computer software presents an attractive alternative to an understanding of the computations, as well as their assumptions and limitations. A two-part pedagogical tutorial exercise is offered as a hands-on laboratory to complement classroom discussions or as a reference for students involved in independent research projects. The exercises are focused on the analysis of ocean waves, specifically wind-generated surface gravity waves. The exercises are cross-disciplinary in nature and can be extended to any other field dealing with random signal analysis. The first exercise introduces the manual arithmetic steps of a finite Fourier analysis of a wave record, develops a spectrum, and compares these results to the results obtained using a fast Fourier transform (FFT). The second part of the exercise, described in the subsequent article, takes a longer wave record and addresses the theoretical and observed wave probability distributions of wave heights and sea surface elevations. These results are then compared to a FFT, thus linking the two pedagogical laboratory exercise parts for a more complete understanding of both exercises.
Addressing student difficulties in applying a wave model to the interference and diffraction of light
Authors: Wosilait Karen , Heron Paula R. L. , Shaffer Peter S. , McDermott Lillian C.
Published: July 2002

This article illustrates the use of research as a basis for the development of curriculum on physical optics. Evidence is presented that university students who have studied physics at the introductory level and beyond often do not have a functional understanding of the wave model for light. Identification and analysis of student difficulties guided the design of a set of tutorials to supplement instruction in a standard calculus-based or algebra-based course. Ongoing assessment was an integral part of the curriculum development process. The instructional materials that resulted have proved to be effective at helping students construct and apply a basic wave model for light.
Bringing atoms into first-year physics
Authors: Chabay Ruth W. , Sherwood Bruce A.
Published: July 2002

We argue that thermal physics should not be treated as a separate topic in introductory physics. The first-year calculus-based college physics should offer a modern, unified view of physics representative of the contemporary scientific enterprise. It should focus on the consequences of the central fact that matter is composed of atoms, and on the process of modeling physical systems. Such a focus is more interesting and relevant to students than a repetition of a purely classical treatment. We give an example of a course that emphasizes physical modeling of phenomena in terms of the atomic nature of matter. Thermal physics is woven into the entire course and is fully integrated with classical and semiclassical mechanics.
The role of leaf structure in vibration propagation
Authors: Magal C. , Schöller M. , Tautz J. , Casas J.
Published: July 2002

The leaf and its structural components play a key role in the propagation of short transient signals produced by insects. In this paper, it is shown how the complex structure of an apple leaf could be modeled by a much simpler one for the analysis of vibratory signal propagation. Waves were produced by impacts of small spheres and the propagation studied using two laser vibrometers, followed by a wavelets analysis. Three components of the leaf were investigated: the midvein, minor veins, and the interspaced homogeneous regions making up the leaf lamina. The loss of signal energy over the leaf lamina and across minor veins and midvein was studied. For the midvein, the loss of energy decreased from 80% at the leaf base to 40% at the apex. For minor veins, the loss of energy decreased from 70% at the leaf base to 31% at the apex. The loss in homogeneous regions was 40%. A signal decomposition into two frequency ranges, above and below 1.7 kHz, showed that the midvein acted as a low-pass filter. As energy loss was mainly a function of vein diameter and not vein type, veins smaller or equal to 0.2 mm were considered as equivalent to homogeneous regions. Hence, a model leaf reduced to the leaf lamina and veins with a diameter >0.2 mm is retained for the study of signal propagation in a leaf.
Ultrasonic cavitation monitoring by acoustic noise power measurement
Authors: Frohly J. , Labouret S. , Bruneel C. , Looten-Baquet I. , Torguet R.
Published: July 2002

In this paper, a new tool is proposed to carry out acoustic cavitation monitoring and to have an overview of its effects in applications. After a brief review of the cavitation characterization techniques, it is shown that cavitation noise is a suitable and accurate indicator of the cavitation activity induced in a liquid. In the first part of this study, the origin of the first spectral component of the cavitation noise is discussed. The f/2 and 2 f component evolution measurement at a driving frequency around 1 MHz confirms Neppiras’ ones and gives an indicator of the cavitation inception. In the second part, the cavitation noise spectrum distortion is considered as a function of the acoustic power transmitted to the liquid in order to obtain an indicator of cavitation activity. In the last part, this new tool is used to bring to the fore the hysteresis effect associated with the cavitation. An experimental correlation between cavitation noise power measurement and the sonochemical activity in an oxidization process is also presented.
Evidence that comodulation detection differences depend on within-channel mechanisms
Authors: Borrill Stephen J. , Moore Brian C. J.
Published: July 2002

The threshold for detecting a narrow-band noise signal in the presence of one or more masking noise bands is higher when the signal and masker bands have the same envelope (i.e., are comodulated) than when they have independent envelopes. This is called a comodulation detection difference (CDD). CDD might be caused by perceptual grouping of the signal and masker bands when they are comodulated. This hypothesis leads to the prediction that some masking should occur for comodulated bands, even when they are widely separated in frequency. An alternative hypothesis is that CDD occurs because, when the signal and masker bands are independent, the signal band can be detected in the dips of the masker envelope. This leads to the prediction that CDD should only occur when the masker produces significant excitation at the signal place. Experiment 1 tested these predictions in a paradigm similar to two-tone masking. The signal was a 20-Hz-wide noise centered at 1500 Hz, and the masker consisted of two bands of noise on either side of the signal frequency, whose envelopes were either comodulated (condition C) or uncorrelated (condition U) with the envelope of the signal band. In a third condition (S), the signal band was replaced by a sinusoid. The frequency separation between the signal and masker bands, Δf, was varied from 100 to 1400 Hz. Thresholds were very similar for conditions U and S; thresholds declined progressively as Δf increased beyond 200 Hz, and reached the absolute threshold for Δf=1400 Hz. For values of Δf from 200 to 1000 Hz, thresholds were higher for condition C than for conditions U or S (i.e., a CDD occurred), but for Δf=1400 Hz thresholds for condition C also reached absolute threshold. In experiment 2, Δf was fixed at 600 Hz and conditions were included where only the upper or the lower masker band was correlated with the signal band. Also, the overall level of the masker was systematically varied. The results indicate that the magnitude of CDD is determined by the comodulation of the signal band with the masker band producing the most masking. Overall, the results support an explanation based on the spread of excitation and dip listening, rather than an explanation based on perceptual grouping.
Interior car sound quality—Assessment of acceleration noises
Authors: Weber Reinhard
Published: July 2002

Investigation of booming noise effects was the reason for the present study. Interior noises of six different cars accelerating from 1500 to 6000 rpm at third gear (full load) were presented over headphones. Seventy normal-hearing subjects (approximately one-third males and two-thirds females) aged from 20 to 60 years (at least 15 subjects per decade) took part in two experiments. After an initial orientation phase, preference judgments were made using a paired comparison paradigm. In experiment 2, the noises were assessed on a bipolar categorical scale (disagreeable/agreeable) with nine subdivisions. Immediately after the experiments, an interview was conducted to learn about the subjects’ impressions about the noises. The preference data were analyzed using MDPREF and compared to the categorical judgment data for different subsets of subjects. The results on subjective data will be presented, together with a correlation analysis on their relationship with a number of acoustical and psychoacoustical signal parameters (level, loudness, sharpness, fluctuation strength, roughness).
Discrimination of musical instrument sounds resynthesized with simplified spectrotemporal parameters
Authors: McAdams Stephen , Beauchamp James W. , Meneguzzi Suzanna
Published: July 2002

The perceptual salience of several outstanding features of quasiharmonic, time-variant spectra was investigated in musical instrument sounds. Spectral analyses of sounds from seven musical instruments (clarinet, flute, oboe, trumpet, violin, harpsichord, and marimba) produced time-varying harmonic amplitude and frequency data. Six basic data simplifications and five combinations of them were applied to the reference tones: amplitude-variation smoothing, coherent variation of amplitudes over time, spectral-envelope smoothing, forced harmonic-frequency variation, frequency-variation smoothing, and harmonic-frequency flattening. Listeners were asked to discriminate sounds resynthesized with simplified data from reference sounds resynthesized with the full data. Averaged over the seven instruments, the discrimination was very good for spectral envelope smoothing and amplitude envelope coherence, but was moderate to poor in decreasing order for forced harmonic frequency variation, frequency variation smoothing, frequency flattening, and amplitude variation smoothing. Discrimination of combinations of simplifications was equivalent to that of the most potent constituent simplification. Objective measurements were made on the spectral data for harmonic amplitude, harmonic frequency, and spectral centroid changes resulting from simplifications. These measures were found to correlate well with discrimination results, indicating that listeners have access to a relatively fine-grained sensory representation of musical instrument sounds.
Pressure-induced interaction between bubbles in a cavitation field
Authors: Kuttruff K. Heinrich
Published: July 2002

This paper describes the interaction between cavities in transient multibubble cavitation which is due to the pressure waves emitted by collapsing bubbles. These waves sum up to a time-dependent “secondary pressure” which accelerates the collapse of contracting bubbles. Since, in each cycle of the exciting sound field the smallest bubbles are the first to implode, this interaction results in an energy transfer from smaller bubbles to larger ones, which undergo particularly violent collapses. This effect is demonstrated by a few examples.
Nonlinear saturation of the thermoacoustic instability
Authors: Karpov S. , Prosperetti A.
Published: July 2002

A weakly nonlinear theory of the thermoacoustic instability in gas-filled tubes is developed in the time domain by exploiting the difference between the instability time scale and the period of standing waves. By carrying the expansion to fourth order in the perturbation parameter, explicit results for the initial growth, nonlinear evolution, and final saturation are obtained. The dependence of the saturation amplitude upon the temperature difference in the stack, the tube geometry, stack plate spacing, Prandtl number, and other parameters is illustrated.
Study of mechanical motions in the basal region of the chinchilla cochlea
Authors: Rhode William S. , Recio Alberto
Published: July 2002

Measurements from the 1–4-mm basal region of the chinchilla cochlea indicate the basilar membrane in the hook region (12–18 kHz) vibrates essentially as it does more apically, in the 5–9-kHz region. That is, a compressive nonlinearity in the region of the characteristic frequency, amplitude-dependent phase changes, and a gain relative to stapes motion that can attain nearly 10 000 at low levels. The displacement at threshold for auditory-nerve fibers in this region (20 dB SPL) was ∼2 nm. Measurements were made at several locations in individual animals in the longitudinal and radial directions. The results indicate that there is little variability in the phase of motion radially and no indication of higher-order modes of vibration. The data from the longitudinal studies indicate that there is a shift in the location of the maximum with increasing stimulus levels toward the base. The cochlear amplifier extends over a 2–3-mm region around the location of the characteristic frequency.
Resin Particles as Flow Units in Poly(vinyl Chloride) Melts
Authors: Berens A. R. , Folt V. L.
Published: July 2002

The melt flow of a variety of poly(vinyl chloride) (PVC) samples was studied at shear rates of 10–5000 sec−1 in a constant-load capillary rheometer. Pronounced differences were observed in apparent viscosity, post-extrusion swelling, and extrudate roughness, depending upon sample preparation and previous history. These differences could not be correlated with molecular weight, molecular weight distribution, or other parameters of molecular structure. A possible explanation was suggested by certain correlations between flow behavior and particle structure or state of fusion. Fracture-surface electron photomicrographs of molded or extruded PVC samples provided clear evidence that resin particles, as formed during polymerization, can maintain their identity and shape during melt flow processes. The melt flow of PVC under some conditions thus must involve the slippage of resin particles past one another, rather than a homogeneous deformation of the melt. Thermal and mechanical history severe enough to obliterate particle identity in fracture-surface photos also shifts melt flow behavior toward higher apparent viscosity and greater melt elasticity, due to a reduction of particle slippage and a more homogeneous flow process. Particle boundaries may be viewed as discontinuities in an entanglement network, and elimination of boundaries as an extension of the network by molecular diffusion. On this basis, our results demonstrate the important contribution of entanglement distribution to polymer melt rheology.
Erythrocyte Rigidity as a Factor in Blood Rheology: Viscoelastic Dilatancy
Authors: Thurston George B.
Published: July 2002

The effects of erythrocyte rigidity on the steady flow viscosity and the oscillatory flow viscoelasticity are examined over a wide range of shear rates. It is found that by hardening the erythrocytes, both the viscosity and the viscoelasticity are generally increased. In addition, the shear rate dependence of the viscoelasticity undergoes an abrupt change in character at higher shear rates. This effect in the viscoelasticity is identified as dilatancy. The elastic component of the complex modulus of viscoelasticity is a particularly sensitive indicator of the rigidity of the cells. These rigidity effects are identified for normal cells, chemically hardened cells, aged cells, and osmotically modified cells.
Viscoelastic and SAXS studies of the structural transition in concentrated aqueous colloids of ovalbumin and serum albumins
Authors: Inoue Hiroshi , Matsumoto Takayoshi
Published: July 2002

Structural transitions in concentrated ovalbumin and bovine serum albumin colloids were studied through rheological and small-angle x-ray scattering (SAXS) measurements. Flow curves and frequency dependence curves of the storage G′ and loss G″ moduli change drastically from a plastic-like to Newtonian-like behavior at a concentration range around 40–50 wt %. This is a solid/liquid transition, which is not a transition induced by addition of electrolytes (free ions). These are the first data on this kind of structural transition at high particle concentrations. The SAXS measurements showed that two phases which have different structures coexist in these systems. One phase is an albumin lattice in which the particles (albumin molecules or their associated particles) disperse uniformly with a certain ordered arrangement and the other has a close-packed structure. The structural transition seems to occur when the albumin lattice can no longer be retained because of the increment in the fraction of the phase of the close-packed structure.
A continuum approach to electrorheology
Authors: Shkel Yuri M. , Klingenberg Daniel J.
Published: July 2002

An equilibrium thermodynamic approach is employed to derive a continuum-level expression for the electric field-induced stress in uniaxial anisotropic materials. Although this model is developed specifically to describe electrorheological and electrostrictive behavior of suspensions, it also applies to other uniaxial materials such as nonpolar nematic liquid crystals, biaxially oriented polymer films, and paper. This model introduces new electrostriction coefficients, which are material parameters that describe the strain dependence of the dielectric tensor as well as the field-induced stresses. An experimental technique for measuring the electrostriction parameters is outlined. An idealized microscopic model is presented to illustrate the relationships between microscopic parameters and the macroscopic electrostriction coefficients. The model is used to determine the stresses in common applications; predictions from the continuum approach agree with direct calculations from a microscopic approach of the normal stress and static shear modulus of electrorheological suspensions.
Fluctuations and self-diffusion of sheared granular material flows
Authors: Hsiau Shu-San , Shieh Yuh-Min
Published: July 2002

Experiments were performed in a shear cell device with adjustable lower wall velocity. Glass spheres with a mean diameter of 3 mm were used as granular materials. Image processing technology and a particle tracking method were employed to measure the average and fluctuation velocities in the streamwise and the transverse directions. Because of gravitation force, the flows consist of both a solid-like region with higher and more uniform velocities in the lower test section and a fluid-like region in the upper part. The velocity fluctuations were anisotropic and were greater in the streamwise direction. By tracking the movements of particles continually, the variation in the mean-square diffusive displacements with time was plotted and the self-diffusion coefficient was determined. The self-diffusion coefficients in the streamwise direction were much higher than those in the transverse direction. The dependence of the diffusion coefficients on the velocity fluctuations and the shear rate were discussed.
Rubber Compounding
Authors: Tallury Syamal S. , Rodgers Brendan , Klingensmith William
Published: May 2022

Rubber compounding is the complex, multidisciplinary science of selecting and blending the appropriate combination of elastomers and other ingredients to meet the performance, manufacturing, environmental, and cost requirements of rubber goods made and used in commerce. There is a wide variety of elastomers and ingredients that are available in making rubber goods, which include all of the following types of products: tires, innertubes, retreaded tires, footwear, conveyor belts, rubber rolls, hoses, belts, weatherstripping, O‐rings, seals, diaphragms, tubing, rubber and latex gloves, ball bladders, medical devices, bumpers, and numerous other products. This is a review of the basic materials used in designing many common types of rubber products. The development of the combination of materials contained in a usable rubber compound involves many disciplines that include chemistry, physics, mathematics, and polymer science. In many cases, classical scientific methods can predict the interaction effects and estimate the properties expected from rubber compounds. However, discovery and development of new materials that modify the rubber compound to produce new, useful, and beneficial properties are appearing regularly. Also, environmental concerns are creating an interest in utilizing recycled rubber products into new rubber compounds, creating uses for postindustrial and ‐consumer materials.
Shaping transient response of nonlinear systems to satisfy a class of integral constraints
Authors: Aalipour Farzad , Das Tuhin
Published: May 2022

We consider the problem of shaping the transient step response of nonlinear systems to satisfy a class of integral constraints. Such constraints are inherent in hybrid energy systems consisting of energy sources and storage elements. While typical transient specifications aim to minimize overshoot, this problem is unique in that it requires the presence of an appreciable overshoot to satisfy the foregoing constraints. The problem was previously studied in the context of linear systems and this article extends that work to nonlinear systems. A combined integral and feedforward control, that requires minimal knowledge of the plant model, is shown to make the system amenable to meeting such constraints. Broadly, the compensation is effective for nonlinear plants with stable open‐loop step response and a positive DC gain. However, stability of the resulting closed‐loop system mandates bounds on the integral gain. In this regard, we state and prove generalized stability theorems for first and higher‐order nonlinear plants.
3D‐Printed Holographic Fresnel Lenses
Authors: Ali Murad , Alam Fahad , Vahdati Nader , Butt Haider
Published: May 2022

Additive manufacturing processes are capable of fabricating optical devices, including the production of contact lenses, waveguides, and Fresnel lenses used in a variety of applications. This study presents a novel fabrication method for high‐quality Fresnel lenses through a vat photopolymerization 3D printing method. Here, the 3D printing process is integrated with the micro/nanostructure fabrication to produce 3D optical components with imprinted micro/nanostructures in a single step. This straightforward approach allows imprinting a micro‐pattern (5 μm features size) onto the flat surface of a 3D‐printed Fresnel lens, achieve light focusing properties along with holographic rainbow effects. The printed lenses achieve focal lengths within ≤8 mm deviation from the predicted values. Such holographic Fresnel lenses are highly desirable in imaging‐based miniature spectrometers for mechanoluminescence sensoring. Thus, the masked stereolithography (MSLA) based 3D printing process can produce normal and holographic Fresnel lenses, vital in optical sensing and communication.
The Non‐Classical Crystallization Mechanism of a Composite Biogenic Guanine Crystal
Authors: Wagner Avital , Ezersky Vladimir , Maria Raquel , Upcher Alexander , Lemcoff Tali , Aflalo Eliahu D. , Lubin Yael , Palmer Benjamin A.
Published: May 2022

Spectacular colors and visual phenomena in animals are produced by light interference from highly reflective guanine crystals. Little is known about how organisms regulate crystal morphology to tune the optics of these systems. By following guanine crystal formation in developing spiders, a crystallization mechanism is elucidated. Guanine crystallization is a “non‐classical,” multistep process involving a progressive ordering of states. Crystallization begins with nucleation of partially ordered nanogranules from a disordered precursor phase. Growth proceeds by orientated attachment of the nanogranules into platelets which coalesce into single crystals, via progressive relaxation of structural defects. Despite their prismatic morphology, the platelet texture is retained in the final crystals, which are composites of crystal lamellae and interlamellar sheets. Interactions between the macromolecular sheets and the planar face of guanine appear to direct nucleation, favoring platelet formation. These findings provide insights on how organisms control the morphology and optical properties of molecular crystals.
Lewis Acid‐catalyzed Tandem Synthesis of Quinazoline‐2,4‐diones by Reaction of Isatins with Aryl/Alkyl Amines using TBHP as Oxidant
Authors: Soda Anil Kumar , Bontha Indrasena Reddy , Chilaka Sai Krishna , Chellu Ramesh Kumar , Madabhushi Sridhar
Published: May 2022

A new and efficient method for preparation of quinazoline‐2,4‐diones by tandem reaction of isatins with aryl/alkyl amines via oxidative rearrangement in the presence of Lewis acid/TBHP is described. This method offers a new approach with wide substrate scope for preparation of quinazoline‐2,4‐diones, in highyields under mild conditions.
In Praise of Mediation Observers
Authors: Hoffman David A.
Published: May 2022

Like many mediators, I am asked from time to time by mediators‐in‐training whether they might observe a mediation. I invariably say “yes,” and they sit in on one or two mediations from start to finish. I consistently hear from them that the experience is valuable, and some say invaluable.
The Science of Hearing Effectively
Authors: Creo Robert Angelo
Published: May 2022

As a young lawyer, I attended informal lunches with senior practitioners and judges at a restaurant which reserved two round tables daily for the legal profession to congregate on an ad hoc basis.
How Active Listening Can Guide a Joint Session
Authors: Dinnar Samuel ‘Mooly’
Published: May 2022

In a private meeting at his corner office, the founder‐CEO told me, “I should have never taken money from these Wall Street barracudas! I knew it! All he cares about is money, and he is squeezing me to satisfy his own greed!”