bluuebunny/crossref_metadata_2025 huggingface dataset:
Hyperphosphorylation and insolubility of α‐synuclein in transgenic mouse oligodendrocytes
Authors: Kahle Philipp J , Neumann Manuela , Ozmen Laurence , Müller Veronika , Jacobsen Helmut , Spooren Will , Fuss Babette , Mallon Barbara , Macklin Wendy B , Fujiwara Hideo , Hasegawa Masato , Iwatsubo Takeshi , Kretzschmar Hans A , Haass Christian
Published: July 2002

(Oligodendro)glial cytoplasmic inclusions composed of α‐synuclein (αSYN) characterize multiple system atrophy (MSA). Mature oligodendrocytes (OLs) do not normally express αSYN, so MSA pathology may arise from aberrant expression of αSYN in OLs. To study pathological deposition of αSYN in OLs, transgenic mice were generated in which human wild‐type αSYN was driven by a proteolipid protein promoter. Transgenic αSYN was detected in OLs but no other brain cell type. At the light microscopic level, the transgenic αSYN profiles resembled glial cytoplasmic inclusions. Strikingly, the diagnostic hyperphosphorylation at S129 of αSYN was reproduced in the transgenic mice. A significant proportion of the transgenic αSYN was detergent insoluble, as in MSA patients. The histological and biochemical abnormalities were specific for the disease‐relevant αSYN because control green fluorescent protein was fully soluble and evenly distributed throughout OL cell bodies and processes. Thus, ectopic expression αSYN in OLs might initiate salient features of MSA pathology.
Effects of dietary calcium on adipocyte lipid metabolism and body weight regulation in energy‐restricted aP2‐agouti transgenic mice
Authors: Shi Hang , DiRienzo Douglas , Zemel Michael B.
Published: July 2002

We have demonstrated previously a regulatory role for intracellular Ca2+ ([Ca2+]i) in adipocyte lipogenesis and lipolysis and have recently reported that 1,25‐(OH)2‐D increases adipocyte [Ca2+]i, which causes increased lipogenesis and decreased lipolysis. We have now tested the hypothesis that suppressing 1,25‐(OH)2‐D by increasing dietary calcium will suppress adipocyte [Ca2+]i, thereby facilitating weight loss by stimulating lipolysis and inhibiting lipogenesis in calorically (Kcal)‐restricted (70% of ad lib) aP2‐agouti transgenic (aP2‐a) mice. Mice (aP2‐a) exhibiting a pattern of obesity gene expression similar to humans were fed a low‐Ca (0.4%)/high‐fat/high‐sucrose diet for six weeks, resulting in a 27% and twofold increase in body weight and total fat pad mass, respectively, with a twofold increase in adipocyte [Ca2+]i (p<0.001). Mice were then either maintained on the same low‐Ca basal diet ad lib or Kcal‐restricted (70% of ad lib) on this diet either unsupplemented (basal) or with 25% or 50% of the protein replaced by non‐fat dry milk (medium or high) dairy or supplemented with CaCO3 to 1.2% Ca for six weeks. Adipocyte [Ca2+]i was unaffected by Kcal restriction but was reduced markedly by all three high Ca diets (290 vs. 130 nM, p<0.001). Body weight was reduced by 11%, 19%, 25%, and 29% by the restricted basal, high‐Ca, medium‐dairy and high‐dairy diets, with corresponding decreases in fat pad mass of 8, 42, 60, and 69% vs. ad lib basal (p<0.001), respectively. The high‐Ca diets caused similar decreases in fatty acid synthase activity 35%‐63%, p<0.001), increases in lipolysis (two‐ to threefold, p<0.001). All three high‐Ca diets increased adipocyte uncoupling protein 2 expression approximately twofold (p<0.02), with a corresponding increase in core temperature (0.48‐0.67°C, p<0.05). Thus, high‐Ca diets suppress adipocyte [Ca2+]i and thereby reduce energy storage and increase thermogenesis during Kcal restriction.
Impaired vascular contractility and blood pressure homeostasis in the smooth muscle α‐actin null mouse
Authors: Schildmeyer Lisa A. , Braun Renee , Taffet George , Debiasi Mariella , Burns Alan E. , Bradley Allan , Schwartz Robert J.
Published: July 2002

The smooth muscle (SM) α‐actin gene activated during the early stages of embryonic cardiovascular development is switched off in late stage heart tissue and replaced by cardiac and skeletal α‐actins. SM α‐actin also appears during vascular development, but becomes the single most abundant protein in adult vascular smooth muscle cells. Tissue‐specific expression of SM α‐actin is thought to be required for the principal force‐generating capacity of the vascular smooth muscle cell. We wanted to determine whether SM α‐actin gene expression actually relates to an actin isoform's function. Analysis of SM α‐actin null mice indicated that SM α‐actin is not required for the formation of the cardiovascular system. Also, SM α‐actin null mice appeared to have no difficulty feeding or reproducing. Survival in the absence of SM α‐actin may result from other actin isoforms partially substituting for this isoform. In fact, skeletal α‐actin gene, an actin isoform not usually expressed in vascular smooth muscle, was activated in the aortas of these SM α‐actin null mice. However, even with a modest increase in skeletal α‐actin activity, highly compromised vascular contractility, tone, and blood flow were detected in SM α‐actin‐defective mice. This study supports the concept that SM α‐actin has a central role in regulating vascular contractility and blood pressure homeostasis, but is not required for the formation of the cardiovascular system.—Schildmeyer, L. A., Braun, R., Taffet, G., DeBiasi, M., Burns, A. E., Bradley, A., and Schwartz, R. J. Impaired vascular contractility and blood pressure homeostasis in the smooth muscle α‐actin null mouse. FASEB J. 14, 2213–2220 (2000)
Observing free-swimming copepods mating
Authors: Strickler J. Rudi
Published: July 2002

Planktonic copepods are small transparent animals swimming in water. To observe how a male finds its mate, special optical systems had to be designed. The animals are treated as phase objects and matched spatial filters allow three-dimensional recordings of the swimming behaviour in a 1-litre vessel. Application of the techniques described shows how a male cyclopoid copepod swims for 20 s in synchronicity with the female before mating. Results stemming from observations with this optical system are published in this volume.
Two–toxin strategies for management of insecticidal transgenic crops: can pyramiding succeed where pesticide mixtures have not?
Authors: Roush R. T.
Published: July 2002

Transgenic insect–resistant crops that express toxins fromBacillus thuringiensis(Bt) offer significant advantages to pest management, but are at risk of losing these advantages to the evolution of resistance in the targeted insect pests. All commercially available cultivars of these crops carry only a single Bt gene, and are particularly at risk where the targeted insect pests are not highly sensitive to the Bt toxin used. Under such circumstances, the most prudent method of avoiding resistance is to ensure that a large proportion of the pest population develops on non–transgenic ‘refuge’ hosts, generally of the crop itself. This has generated recommendations that 20% or more of the cotton and maize in any given area should be non–transgenic. This may be costly in terms of yields and may encourage further reliance on and resistance to pesticides. The use of two or more toxins in the same variety (pyramiding) can reduce the amount of refuge required to delay resistance for an extended period. Cross–resistance among the toxins appears to have been overestimated as a potential risk to the use of pyramids (and pesticide mixtures) because cross–resistance is at least as important when toxicants are used independently. Far more critical is that there should be nearly 100% mortality of susceptible insects on the transgenic crops. The past failures of pesticide mixtures to manage resistance provide important lessons for the most efficacious deployment of multiple toxins in transgenic crops.
The future of philosophy
Authors: Searle John R.
Published: July 2002

There is no sharp dividing line between science and philosophy, but philosophical problems tend to have three special features. First, they tend to concern large frameworks rather than specific questions within the framework. Second, they are questions for which there is no generally accepted method of solution. And third they tend to involve conceptual issues. For these reasons a philosophical problem such as the nature of life can become a scientific problem if it is put into a shape where it admits of scientific resolution. Philosophy in the 20th century was characterized by a concern with logic and language, which is markedly different from the concerns of earlier centuries of philosophy. However, it shared with the European philosophical tradition since the 17th century an excessive concern with issues in the theory of knowledge and with scepticism. As the century ends, we can see that scepticism no longer occupies centre stage, and this enables us to have a more constructive approach to philosophical problems than was possible for earlier generations. This situation is somewhat analogous to the shift from the sceptical concerns of Socrates and Plato to the constructive philosophical enterprise of Aristotle. With that in mind, we can discuss the prospects for the following six philosophical areas: (i) the traditional mind–body problem; (ii) the philosophy of mind and cognitive science; (iii) the philosophy of language; (iv) the philosophy of society; (v) ethics and practical reason; (vi) the philosophy of science. The general theme of these investigations, I believe, is that the appraisal of the true significance of issues in the philosophy of knowledge enables us to have a more constructive account of various other philosophical problems than has typically been possible for the past three centuries.
Rho GTPases: molecular switches that control the organization and dynamics of the actin cytoskeleton
Authors: Hall Alan , Nobes Catherine D.
Published: July 2002

The actin cytoskeleton plays a fundamental role in all eukaryotic cells—it is a major determinant of cell morphology and polarity and the assembly and disassembly of filamentous actin structures provides a driving force for dynamic processes such as cell motility, phagocytosis, growth cone guidance and cytokinesis. The ability to reorganize actin filaments is a fundamental property of embryonic cells during development; the shape changes accompanying gastrulation and dorsal closure, for example, are dependent on the plasticity of the actin cytoskeleton, while the ability of cells or cell extensions, such as axons, to migrate within the developing embryo requires rapid and spatially organized changes to the actin cytoskeleton in response to the external environment. W ork in mammalian cells over the last decade has demonstrated the central role played by the highly conserved Rho family of small GTPases in signal transduction pathways that link plasma membrane receptors to the organization of the actin cytoskeleton.
Peroxide processing in photosynthesis: antioxidant coupling and redox signalling
Authors: Noctor Graham , Veljovic-Jovanovic Sonja , Foyer Christine H.
Published: July 2002

Photosynthesis has a high capacity for production of hydrogen peroxide (H
2
O
2
), but the intracellular levels of this relatively weak oxidant are controlled by the antioxidant system, comprising a network of enzymatic and non-enzymatic components that notably includes reactions linked to the intracellular ascorbate and glutathione pools. Mutants and transformed plants with specific decreases in key components offer the opportunity to dissect the complex system that maintains redox homeostasis. Since H
2
O
2
is a signal-transducing molecule relaying information on intracellular redox state, the pool size must be rigorously controlled within each compartment of the cell. This review focuses on compartment-specific differences in the stringency of redox coupling between ascorbate and glutathione, and the significance this may have for the flexibility of the control of gene expression that is linked to photosynthetic H
2
O
2
production.
The role of CD154 in organ transplant rejection and acceptance
Authors: Kirk Allan D. , Blair Patrick J. , Tadaki Douglas K. , Xu He , Harlan David M.
Published: July 2002

CD154 plays a critical role in determining the outcome of a transplanted organ. This simple statement is amply supported by experimental evidence demonstrating that anti–CD154 antibodies are potent inhibitors of allograft rejection in many rigorous transplant models. Unfortunately, despite intensive investigation over the past ten years, the precise mechanisms by which antibodies against CD154 exert their anti–rejection effects have remained less obvious. Though originally classified with reference to B–cell function, CD154–CD40 interactions have also been shown to be important in T cell–antigen–presenting cell interactions. Accordingly, CD154 has been classified as a T–cell co–stimulatory molecule. However, mounting data suggest that treatment with anti–CD154 antibodies does not simply block costimulatory signals, but rather that the antibodies appear to induce signalling in receptor–bearing T cells. Other data suggest that anti–CD154 effects may be mediated by endothelial cells and possibly even platelets. In fact, the current literature suggests that CD154 can either stimulate or attenuate an immune response, depending upon the model system under study. CD154 has secured a fundamental place in transplant biology and general immunology that will no doubt be the source of considerable investigation and therapeutic manipulation in the coming decade.
Gaia as a complex adaptive system
Authors: Lenton Timothy M. , van Oijen Marcel
Published: July 2002

We define the Gaia system of life and its environment on Earth, review the status of the Gaia theory, introduce potentially relevant concepts from complexity theory, then try to apply them to Gaia. We consider whether Gaia is a complex adaptive system (CAS) in terms of its behaviour and suggest that the system is self–organizing but does not reside in a critical state. Gaia has supported abundant life for most of the last 3.8 Gyr. Large perturbations have occasionally suppressed life but the system has always recovered without losing the capacity for large–scale free energy capture and recycling of essential elements. To illustrate how complexity theory can help us understand the emergence of planetary–scale order, we present a simple cellular automata (CA) model of the imaginary planet Daisyworld. This exhibits emergent self–regulation as a consequence of feedback coupling between life and its environment. Local spatial interaction, which was absent from the original model, can destabilize the system by generating bifurcation regimes. Variation and natural selection tend to remove this instability. With mutation in the model system, it exhibits self–organizing adaptive behaviour in its response to forcing. We close by suggesting how artificial life (‘Alife’) techniques may enable more comprehensive feasibility tests of Gaia.
The budding yeast protein kinase Ipl1/Aurora allows the absence of tension to activate the spindle checkpoint
Authors: Biggins Sue , Murray Andrew W.
Published: July 2002

The spindle checkpoint prevents cell cycle progression in cells that have mitotic spindle defects. Although several spindle defects activate the spindle checkpoint, the exact nature of the primary signal is unknown. We have found that the budding yeast member of the Aurora protein kinase family, Ipl1p, is required to maintain a subset of spindle checkpoint arrests. Ipl1p is required to maintain the spindle checkpoint that is induced by overexpression of the protein kinase Mps1. Inactivating Ipl1p allows cells overexpressing Mps1p to escape from mitosis and segregate their chromosomes normally. Therefore, the requirement for Ipl1p in the spindle checkpoint is not a consequence of kinetochore and/or spindle defects. The requirement for Ipl1p distinguishes two different activators of the spindle checkpoint: Ipl1p function is required for the delay triggered by chromosomes whose kinetochores are not under tension, but is not required for arrest induced by spindle depolymerization. Ipl1p localizes at or near kinetochores during mitosis, and we propose that Ipl1p is required to monitor tension at the kinetochore.
Is There a Bias in Proteome Research?
Authors: Mrowka Ralf , Patzak Andreas , Herzel Hanspeter
Published: July 2002

Advances in technology have enabled us to take a fresh look at data acquired by traditional single experiments and to compare them with genomewide data. The differences can be tremendous, as we show here, in the field of proteomics. We have compared data sets of protein-protein interactions in Saccharomyces cerevisiae that were detected by an identical underlying technical method, the yeast two-hybrid system. We found that the individually identified protein-protein interactions are considerably different from those identified by two genomewide scans. Interacting proteins in the pooled database from single publications are much more closely related to each other with respect to transcription profiles when compared to genomewide data. This difference may have been introduced by two factors: by a selection process in individual publications and by false positives in the whole-genome scans. If we assume that the differences are a result of false positives in the whole-genome data, the scans would contain 47%, 44%, and 91% of false positives for the UETZ, ITO-core, and ITO-full data, respectively. If, however, the true fraction of false positives is considerably lower than estimated here, the data from hypothesis-driven experiments must have been subjected to a serious selection process.
Smoothing intensity‐modulated beam profiles to improve the efficiency of delivery
Authors: Spirou Spiridon V. , Fournier‐Bidoz Nathalie , Yang Jie , Chui Chen‐Shou , Ling Clifton C.
Published: July 2002

Intensity‐modulated beam profiles are generated by an inverse planning or optimization algorithm, a process that, being computationally complex and intensive, is inherently susceptible to noise and numerical artifacts. These artifacts make delivery of the beams more difficult, oftentimes for little, if any, observable improvement in the dose distributions. In this work we examine two approaches for smoothing the beam profiles. The first approach is to smooth the beam profiles subsequent to each iteration in the optimization process (method A). The second approach is to include a term within the objective function that specifies the smoothness of the profiles as an optimization criterion (method B). The two methods were applied to a phantom study as well as three clinical sites: paraspinal, nasopharynx, and prostate. For the paraspinal and nasopharynx cases, which have critical organs with low tolerance doses in close proximity, method B produced sharper dose gradients, better target dose homogeneity, and more critical organ sparing. In the less demanding prostate case, the two methods give similar results. In addition, method B is more efficient during optimization, requiring fewer iterations, but less efficient during DMLC delivery, requiring a longer beam‐on time.
Magnetic resonance imaging of temperature changes during interstitial microwave heating: A phantom study
Authors: Vitkin I. A. , Moriarty J. A. , Peters R. D. , Kolios M. C. , Gladman A. S. , Chen J. C. , Hinks R. S. , Hunt J. W. , Wilson B. C. , Easty A. C. , Bronskill M. J. , Kucharczyk W. , Sherar M. D. , Henkelman R. M.
Published: July 2002

Changes in magnetic resonance (MR) signals during interstitial microwave heating are reported, and correlated with simultaneously acquired temperature readings from three fiber‐optic probes implanted in a polyacrylamide gel phantom. The heating by a MR‐compatible microwave antenna did not interfere with simultaneous MR image data acquisition. MR phase‐difference images were obtained using a fast two‐dimensional‐gradient echo sequence. From these images the temperature‐sensitive resonant frequency of the 1H nuclei was found to decrease approximately by 0.008 ppm/°C. The method and results presented here demonstrate that noninvasive MR‐temperature imaging can be performed simultaneously with interstitial microwave thermal treatment.
A gradient inverse planning algorithm with dose‐volume constraints
Authors: Spirou Spiridon V. , Chui Chen‐Shou
Published: July 2002

An inverse planning algorithm for determining the intensity‐modulated beams that will most closely generate a desired dose distribution is presented. The algorithm is three‐dimensional and does not explicitly depend on beam energies and modalities. It allows a single prescription dose or a window of acceptable doses to be specified for the target, with additional constraints to account for under‐ or over‐dosing. For the protection of organs at risk, it provides maximum‐dose and dose‐volume constraints. The latter apply to the entire volume of the organ exposed to the corresponding dose levels. Several levels of each type of constraint, with varying penalty weights, may be specified for each organ. The objective function that serves as the measure of the goodness of the solution is of the least‐squares type and is minimized using conjugate gradient methods. Typical clinical cases involving 40 000 points and 4 000 rays to be determined require about 10 min of CPU time on a DEC AlphaStation. Results are presented for two clinical sites, prostate and lung. The optimization algorithm yielded plans that featured higher target dose homogeneity, compared with the human planner's plan, while selectively sparing more of the normal organs at the desired dose regions.
Technique to obtain positron emission mammography images in registration with x‐ray mammograms
Authors: Bergman Alanah M. , Thompson Christopher J. , Murthy Kavita , Robar James L. , Clancy Raymond L. , English Michael J. , Loutfi Antoine , Lisbona Robert , Gagnon Jean
Published: July 2002

X‐ray mammograms reveal abnormal tissue densities, while metabolic images identify regions of abnormal metabolism. Conventional nuclear medicine and radiologic breast images must be acquired at different times with different patient positions making coregistration difficult. Accurate coregistration of metabolic and x‐ray images of the breast is likely to be important when acquiring information about the location and diagnosis of suspicious lesions or tumors. Our PEM‐1 (positron emission mammography) system detects metabolic activity within the breast. The two planar detectors are integrated into a conventional x‐ray mammography unit. This arrangement simplifies the image registration process by allowing a breast metabolic image to be acquired immediately after performing an x‐ray mammogram. The patient is not moved between procedures. A coregistration tool has also been developed. A thin plastic sheet with a wire frame protrudes from the side of the upper PEM detector. With the tool positioned over the suspicious area of the breast, a magnified film density image is made using the available x‐ray equipment. A radio‐opaque rectangular outline of the wire frame is visible on the film image. During a positron emission metabolic scan, detectors acquire a image of the same region. The PEM detectors can be positioned anywhere along the width of the breast. This provides an image of a particular region of interest. Several contiguous images may be combined to provide a complete scan.
A mathematical model for correcting patient setup errors using a tilt and roll device
Authors: Litzenberg Dale W. , Balter James M. , Hornick David C. , Lam Kwok L. , Ten Haken Randall K.
Published: July 2002

An algorithm is presented for determining how to adjust the actuators of a tilt and roll table. The algorithm is based on a geometrical model of the table, which was designed with six degrees of freedom. This design and algorithm allows complete translational and rotational corrections to be applied to the target volume position on a daily basis.
Anthropomorphic versus geometric chest phantoms: A comparison of scatter properties
Authors: Baydush Alan H. , Ghem Wendy C. , Floyd Carey E.
Published: July 2002

Previously, we have used an anthropomorphic chest phantom to study scatter reduction in digital chest radiography. Image metrics, such as scatter fractions, contrast, noise, and resolution, are not easily measured due to the anatomical structure in the phantom. A geometric chest phantom, recently developed for quality control purposes, offers the possibility of being used to calculate image quality measurements. Here, we compare the scatter properties of the two phantoms to determine if the geometric phantom can be used in our studies of scatter compensation techniques. A calibrated photostimulable phosphor system was used to acquire images of the two phantoms. An array of beam stops was placed in front of each phantom to calculate scatter fractions. Each phantom had approximately 2 in. of polystyrene material added to the posterior to increase scatter fractions to those normally seen in patients. Exposure parameters were 300 mA for 0.009 sec with a source to image distance of 100 cm. Energies were varied from 60 to 130 kVp. Scatter fractions were determined for different areas of anatomy for each energy and each phantom. For all energies examined, the two phantoms compare well for scatter fractions in each of six regions. For example, at 95 kVp, the geometric phantom had average scatter fractions of 0.72 and 0.88 in the lung and mediastinum regions, respectively. These values were 0.74 and 0.90 for the anatomic phantom. For comparison, measurements of scatter fractions in patients at these values have been reported as 0.65 and 0.90 for the lung and mediastinum regions. The geometric phantom is an excellent tool which can be used in place of the anthropomorphic phantom for studies involving scatter compensation. In addition to having a gray level histogram typical of a human chest, this phantom has uniform regions where image quality measurements can be calculated.
Monte Carlo validation in diagnostic radiological imaging
Authors: Boone John M. , Buonocore Michael H. , Cooper Virgil N.
Published: July 2002

Monte Carlo analysis in the radiological sciences has been used for several decades, however with the ever‐increasing power of desktop computers, the utility of Monte Carlo simulation is increasing. A Monte Carlo code called the Simple Investigative Environment for Radiological Research Applications (SIERRA) is described mathematically, and is then compared against an array of published and unpublished results determined by other means. A series of 32 comparisons between data sets, 22 from independent Monte Carlo simulations and 10 from physically measured data, were assessed. The compared parameters included depth dose curves, lateral energy scattering profiles, scatter to primary ratios, normalized glandular doses, angular scattering distributions, and computed tomography dose index (CTDI) values. Three of the 32 comparison data sets were excluded as they were identified as outliers. Of the remaining 29 data sets compared, the mean differences ranged from −14.8% to +17.2%, and the average of the mean differences was 0.12%and the median difference was 1.57%. Fifty percent of the comparisons showed mean differences ofor less, and 93% of the comparisons showed mean differences of 12% or less. We conclude that for research applications in diagnostic radiology, the SIERRA Monte Carlo code demonstrates accuracy and precision to well within acceptable levels.
Objectivity, retrocausation, and the experiment of Englert, Scully, and Walther
Authors: Mohrhoff Ulrich
Published: July 2002

In a recent contribution to this journal [Am. J. Phys. 64, 1468–1475 (1996)] I wrongly asserted that retrocausation in the Englert, Scully, and Walther (ESW) experiment (a double-slit interference experiment with atoms) can occur only until the atom arrives at the screen. In their response, Englert, Scully, and Walther [preceding paper] point out my fallacy but give an incomplete analysis of its origin. In this paper I trace this fallacy to a deep-seated preconception about time and reality. I show that among the two possible realistic interpretations of standard quantum mechanics, the reality-of-states view and the reality-of-phenomena view, only the latter is viable. It follows that retrocausation is a necessary feature of any realistic account of the ESW experiment based on standard quantum mechanics. Finally I eludicate the sense in which the spatial properties of quantum systems are objective, and show that they are extrinsic rather than intrinsic.
Sensor scheme design for active structural acoustic control
Authors: Berkhoff Arthur P.
Published: July 2002

Efficient sensing schemes for the active reduction of sound radiation from plates are presented based on error signals derived from spatially weighted plate velocity or near-field pressure. The schemes result in near-optimal reductions as compared to weighting procedures derived from eigenvector or singular vector analysis of the radiation operator. Efficient control configurations are suggested using a, possibly analog, front-end implementing a bank of spatial weighting functions and a digital controller with a minimized number of input and output channels. The performance of different weighting functions is compared, as well as the performance of different frequency-dependent filtering functions. Design rules are given for the sensor spacing, the number of weighting functions, the number of actuators, and the corresponding controller dimensionality.
Pressure dependence of the elasticity of a steel sphere measured by the cavity resonance method
Authors: Ohno Ichiro , Kimura Masaki , Hanayama Yoichi , Oda Hitoshi , Suzuki Isao
Published: July 2002

The pressure derivatives of elastic moduli of a steel sphere were measured by the cavity resonance method, a modified resonant sphere technique under gas pressure using a spherical three-layered structure (3LS) consisting of a sample-thin gas layer–cavity container system. The pressure-induced shifts of resonance peaks of both toroidal and spheroidal modes were observed up to 100 MPa (1 kbar) under gas pressure with helium gas. The resultant pressure derivatives of frequencies of toroidal modes yielded a pressure derivative of shear modulus of ∂G/∂P=2.01±0.08. The pressure derivative of the bulk modulus was determined from the data of spheroidal modes, ∂K/∂P=5.0±0.4, by analyzing these data as free oscillations of the 3LS superimposed on the static compression. The results demonstrate the efficiency of the cavity resonance method for measuring pressure derivatives of elastic moduli of solids.
Seabed classification from acoustic profiling data using the similarity index
Authors: Kim Han-Joon , Chang Jae-Kyeong , Jou Hyeong-Tae , Park Gun-Tae , Suk Bong-Chool , Kim Ki Young
Published: July 2002

We introduce the similarity index (SI) for the classification of the sea floor from acoustic profiling data. The essential part of our approach is the singular value decomposition of the data to extract a signal coherent trace-to-trace using the Karhunen–Loeve transform. SI is defined as the percentage of the energy of the coherent part contained in the bottom return signals. Important aspects of SI are that it is easily computed and that it represents the textural roughness of the sea floor as a function of grain size, hardness, and a degree of sediment sorting. In a real data example, we classified a section of the sea floor off Cheju Island south of the Korean Peninsula and compared the result with the sedimentology defined from direct sediment sampling and side scan sonar records. The comparison shows that SI can efficiently discriminate the bottom properties by delineating sediment-type boundaries and transition zones in more detail. Therefore, we propose that SI is an effective parameter for geoacoustic modeling.
Modified Herschel–Quincke tube: Attenuation and resonance for n-duct configuration
Authors: Selamet A. , Easwaran V.
Published: July 2002

The classical two-duct Herschel–Quincke tube is generalized to an n-duct configuration. A closed-form expression is developed for the transmission loss characteristics, as well as for the resonance locations. While the results are illustrated in the present study in terms of three-duct configurations alone and in comparison with the two-duct arrangements, the developed expressions hold for any number of ducts and cross-sectional area combination.
Energy flow analysis for curved beams
Authors: Le Bot A. , Ichchou M. N. , Jezequel L.
Published: July 2002

This paper presents an energy model for the medium- and high-frequency analysis of Love–Kirchhoff curved beams. This model introduced by Nefske and Sung [Statistical Energy Analysis NCA 3, 47–54 (1987)] for straight beams and investigated further by other authors, is developed for curved rods (tangential or longitudinal waves), and then for curved beams (radial or flexural waves). The exact-energy solution for curved rods or beams is shown to consist of a smooth spatial variation, which the energy model represents, and a spatially oscillating solution, which can be represented by an energy envelope. Finally, a complete energy model is proposed for curved components including both longitudinal and flexural waves. Boundary conditions are also given in this paper. It is shown that this method, which is numerically attractive in the mid- and high-frequency range, predicts the arithmetic mean value of the energy variables.
The relationship of scattered subharmonic, 3.3-MHz fundamental and second harmonic signals to damage of monolayer cells by ultrasonically activated Albunex®
Authors: Miller Douglas L. , Bao Shiping
Published: July 2002

Cultured Chinese hamster ovary cells attached to thin Mylar sheets were exposed to 3.3-MHz ultrasound in the presence of Albunex® ultrasound contrast agent. The ultrasound beam was directed upward at the exposure chamber with the monolayer on the inside of the upper acoustic window. Cell membrane damage was detected by the firefly enzyme assay for released ATP and the subharmonic, fundamental, and second harmonic scattered signals were recorded. ATP release increased monotonically with increasing pressure amplitude above apparent thresholds of 0.28 MPa for 1-s continuous and 0.56 MPa for 100-s pulsed (10-μs pulses, 1-ms PRP) exposures with 5% Albunex®. The subharmonic signal and, to a lesser extent, the second harmonic signal both increased with the cell membrane damage, which suggests that these signals have predictive value for bioeffects. If the monolayer was positioned on the front window of the exposure chamber, cell membrane damage was greatly reduced, which confirms the protective influence of this configuration of monolayers reported in the literature. The effect decreased both at high (50%) or low (0.5%) concentrations of Albunex®. The strong nonlinear scattering of ultrasound by contrast agent gas bodies appears to provide useful indicators of gas body activity including cavitational bioeffects.
Three-dimensional impulse response measurements on S. Maria Church, Florence, Italy
Authors: Farina Angelo , Tronchin Lamberto
Published: July 2002

The measurement of binaural impulse response procedure for acoustic environments has been established and achieved from the International Standard Organization; following the ISO 3382 many acoustical parameters have been already analyzed in the past, ranging from Royal Albert Hall in London, UK, to Teatro la Fenice in Venice, Italy. In this paper a new procedure for measuring 3D impulse response has been utilized, with the aim to reconstruct the 3D sound field especially for virtual reality purposes. Starting from the definition of B-format impulse responses, the pressure gradient has been measured in the Church by using a homemade apparatus and software, and performing measurements on the three axes, gathering seven different impulse responses, without using expensive microphones already developed. From the measures, the relations between the seven different measurements have been found out, and the results have been compared with the binaural impulse responses measurements performed in the same position at the same time.
Methods of interval selection, presence of noise and their effects on detectability of repetitions and prolongations
Authors: Howell Peter , Staveley Alison , Sackin Stevie , Rustin Lena
Published: July 2002

Accurate methods for locating specific types of stuttering events are necessary for diagnosis, treatment, and prognosis. A factor that could add variability to assessment of stuttering is noise on recordings. The effects of noise were assessed by adding noise to intervals of speech containing all fluent material, fluent material with a repetition, or fluent material with a prolongation. These intervals allow a unique dysfluency response to be made. A statistical analysis of the occurrence of such intervals in spontaneous speech showed that only a limited number of intervals met these criteria. This demonstrated that selecting intervals at random from spontaneous speech (as in time interval analysis procedure) will infrequently lead to a unique and unambiguous dysfluency specification for the interval. Intervals were selected for testing from the intervals that met the stipulated criteria. These were presented for dysfluency judgment when the position of the stuttering within an interval was varied and with different amounts of added noise (no added noise, 3 dB, and 6 dB of noise relative to mean speech amplitude). Accuracy in detecting stuttering type depended on noise level and the stuttering’s position in the interval, both of which also depended on the type of stuttering: Noise level affected detection of repetitions more than prolongations: Repetitions were more difficult to detect when they occurred at the end of an interval whereas prolongations were more difficult to detect when they were at the beginning of an interval. The findings underline the importance of adopting rigorous recording standards when speech is to be employed to make stuttering assessments.
Acoustics of children’s speech: Developmental changes of temporal and spectral parameters
Authors: Lee Sungbok , Potamianos Alexandros , Narayanan Shrikanth
Published: July 2002

Changes in magnitude and variability of duration, fundamental frequency, formant frequencies, and spectral envelope of children’s speech are investigated as a function of age and gender using data obtained from 436 children, ages 5 to 17 years, and 56 adults. The results confirm that the reduction in magnitude and within-subject variability of both temporal and spectral acoustic parameters with age is a major trend associated with speech development in normal children. Between ages 9 and 12, both magnitude and variability of segmental durations decrease significantly and rapidly, converging to adult levels around age 12. Within-subject fundamental frequency and formant-frequency variability, however, may reach adult range about 2 or 3 years later. Differentiation of male and female fundamental frequency and formant frequency patterns begins at around age 11, becoming fully established around age 15. During that time period, changes in vowel formant frequencies of male speakers is approximately linear with age, while such a linear trend is less obvious for female speakers. These results support the hypothesis of uniform axial growth of the vocal tract for male speakers. The study also shows evidence for an apparent overshoot in acoustic parameter values, somewhere between ages 13 and 15, before converging to the canonical levels for adults. For instance, teenagers around age 14 differ from adults in that, on average, they show shorter segmental durations and exhibit less within-subject variability in durations, fundamental frequency, and spectral envelope measures.
Loss of natural soundscapes within the Americas
Authors: Krause Bernie
Published: July 2002

Species specific calls within an ecosystem evolve to adjust to the physical acoustic constraints of that ecosystem as well as the constraints imposed by the spectal content of the calls of other species occupying that ecosystem. The result is a rich texture of sound spread over both the audible (human) and inaudible spectrum with changing patterns at different times of the day. Based on 30 years of experience in recording natural soundscapes, the author documents the loss of natural soundscapes within the U.S. and other countries of the Americas. The results are demonstrated with field recordings.
Spectral cues and perception of the vertical position of targets by the big brown bat, Eptesicus fuscus
Authors: Wotton J. M. , Simmons J. A.
Published: July 2002

Big brown bats (Eptesicus fuscus) were trained to discriminate between vertical angles subtended by paired beads suspended from fishing line. Bats were rewarded for choosing the smaller of the two angles presented. The difference between the angles was changed systematically using a transformed up–down procedure and the bats’ ability to detect the difference was measured at different vertical locations. When the beads were centered at +20° (above the horizon), at 0° (the horizon), and at −20° (below the horizon), vertical angle acuity (VAA) was maintained between 2.9° and 4.1°. At more extreme vertical positions both bats showed loss of acuity; when the beads were centered around −40°, VAA was 6.7° or 8.3° and at +40, VAA was worse than 21° (the largest difference tested). When the tragi of both ears were bent down and glued to the side of the face, bats showed severe loss of acuity for beads centered at −20° (VAA 18.3° and 20.1°), but maintained their angle acuity for beads centered at +20° (VAA 3.8° and 4.9°). The results are consistent with the spectral cues created by the filtering of the external ear.
Manifestation of ray stochastic behavior in a modal structure of the wave field
Authors: Virovlyansky A. L.
Published: July 2002

A ray-based mathematical formalism is described to analyze modal structure variations in a range-dependent wave guide. In the scope of this formalism mode amplitudes are expressed through parameters of ray trajectories. Therefore, the approach under consideration provides a convenient tool to study how chaotic ray motion manifests itself in an irregular range dependence of the modal structure. The phenomenon of nonlinear ray-medium resonance playing a crucial role in the emergence of ray chaos has been interpreted from the viewpoint of normal modes. It has been shown that in terms of modes the coexistence of regular and chaotic rays means the presence of regular and irregular constituents of mode amplitudes. An analog to incoherent summation of rays has been proposed to evaluate mode intensities (squared mode amplitudes) smoothed over the mode number. Numerical calculations have shown that it gives correct results for smoothed mode intensities at surprisingly long ranges.
Tear Phenomena around Solid Inclusions in Castable Elastomers
Authors: Oberth A. E. , Bruenner R. S.
Published: July 2002

Adhesion studies on spherical particles imbedded in elastomers have shown that cohesive failure of the binder phase always precedes dewetting. The latter is a sudden and irreversible process resulting in permanent damage to the system. Cohesive failure manifests itself in the formation of a number of small holes near the surface of the filler particle. The stress σ′ causing these holes is well defined and depends only on the elastic modulus E of the binder: σ′=E/2+C. The further propagation of these initial tears depends on the consistency of the boundary layer surrounding the solid inclusion. In case of no modulus gradient or a softer boundary layer, tear propagation leads to the complete separation of the elastomeric binder from the particle. High modulus layers, which are linked to the polymeric matrix by primary chemical bonds, prevent a dewetting. It is shown that the complex response of filled elastomers can be explained in terms of the above results.
Vibrational Measurements with Large Amplitudes
Authors: Philippoff W.
Published: July 2002

Using a new instrument, the influence of the shear amplitude s0 on the dynamic behavior of polymer solutions up to 700% shear was investigated. At amplitudes <∼100% shear, the dynamic viscosity η1 remained constant, as required by linear viscoelasticity; however, the shear storage modulus G′ decreased considerably. The steady-state flow curve forms the envelope of curves measured with different amplitudes and frequencies, predominantly in the range of higher rates of shear. The more complete analysis of the results is forthcoming.
Time Dependent Viscoelastic Properties of Concentrated Polymer Solutions
Authors: Sakai Mototsugu , Fukaya Hisashi , Nagasawa Mitsuru
Published: July 2002

Measurements of stress growth and stress relaxation after onset and cessation of steady simple shear flow in concentrated polymer solutions were carried out with a Weissenberg rheogoniometer R-17 having a gap servo system. By using monodisperse polymers and their blends, the effect of molecular weight distribution on those transient phenomena is discussed. The so-called stress-overshoot was observed in both experiments of shear and normal stress growths. Ratio of the time of the maximum normal stress difference and that of the maximum shear stress is close to 2 at the limit of low shear rate for both monodisperse and polydisperse polymers. In the range of finite shear rate, the ratio is remarkably dependent on shear rate for polydisperse samples, whereas it is almost independent of shear rate for monodisperse polymers. Shear rate dependence of the ratio of the apparent relaxation time of normal stress difference and that of shear stress in stress relaxation experiments is also found to be remarkably affected by molecular weight distribution. From a comparison between these experiments and theories so far published, it is concluded that these transient phenomena may be explained by assuming that the relaxation spectrum is a function of shear rate at least if the shear rates are not too high. The comparison between theory and experiments is carried out without assuming explicit forms for relaxation spectrum.
Large Axisymmetric Inflation of a Nonlinear Viscoelastic Membrane by Lateral Pressure
Authors: Wineman Alan S.
Published: July 2002

The large axisymmetric deformation of a plane circular membrane into surfaces of revolution by a lateral pressure is considered. The material is taken to be a styrene-butadiene rubber for which a nonlinear integral type constitutive equation incorporating measured properties has been presented by McGuirt and Lianis [Trans. Soc. Rheol., 14, 117, (1970)]. The formulation is reduced to a two-point boundary value problem governed by a system of nonlinear partial differential-integral equations of Volterra type for principal stretch ratios and a related kinematic variable. A numerical procedure is outlined which reduces at each time step to solving a system of equations having the same general structure as that for the corresponding problem assuming the membrane to be elastic. Stretch ratio and stress variation and deformed profile histories are computed for prescribed pressure histories, the latter being most useful for comparison of predictions and experiment.
Visualization of Sentinel Lymph Nodes with Mannosylated Fluorescent Nanodiamonds
Authors: Kvakova Klaudia , Ondra Martin , Schimer Jiri , Petrik Milos , Novy Zbynek , Raabova Helena , Hajduch Marian , Cigler Petr
Published: March 2022

The present study focuses on the development of a sensitive and specific approach for the visualization of sentinel lymph nodes draining the tumor using ultrabright 200‐nm fluorescent nanodiamonds (FNDs) equipped with a designed targeting surface architecture. The FNDs with a narrow size distribution are isolated by differential centrifugation, colloidally stabilized with alkyne‐functionalized poly(glycerol) and modified with a polyvalent array of mannose (FND‐p‐Man). In vitro experiments demonstrate an outstanding increase of the particle internalization by the mannose receptor CD206 (MR) and no significant toxicity. MR involvement is confirmed by blocking ligand binding with mannan and a 15.2 mAb (specific anti‐MR) in J774A.1 mouse macrophage cell line. In vivo mouse experiments confirm increased retention of FND‐p‐Man in sentinel lymph nodes of both healthy and B16 melanoma bearing animals. These results suggest that FND‐p‐Man has potential as a tracer for lymph node visualization in locoregional perioperative cancer diagnostics and as a tool for endoscopic/robotic fluorescence‐guided surgery.