bluuebunny/crossref_metadata_2025 huggingface dataset:
Essential Role of P-Selectin in the Initiation of the Inflammatory Response Induced by Hemorrhage and Reinfusion
Authors: Scalia Rosario , Armstead Valerie E. , Minchenko Alexander G. , Lefer Allan M.
Published: July 2002

Resuscitation from hemorrhage induces profound pathophysiologic alterations and activates inflammatory cascades able to initiate neutrophil accumulation in a variety of tissues. This process is accompanied by acute organ damage (e.g., lungs and liver). We have previously demonstrated that significant leukocyte–endothelium interactions occur very early in other forms of ischemia/reperfusion (i.e., splanchnic ischemia/reperfusion and traumatic shock) which are largely mediated by increased expression of the adhesion molecule, P-selectin, on the vascular endothelium. Here we postulated that increased endothelial expression of P-selectin in the microvasculature would play an essential role in initiating the inflammatory signaling of hemorrhagic shock. Using intravital microscopy, we found that hemorrhagic shock significantly increased the number of rolling and adherent leukocytes in the mouse splanchnic microcirculation. In contrast, mice genetically deficient in P-selectin, or wild-type mice given either an anti–P-selectin monoclonal antibody or a recombinant soluble P-selectin glycoprotein ligand (PSGL)-1 immunoglobulin, exhibited markedly attenuated leukocyte–endothelium interaction after hemorrhagic shock. Thus, activation of P-selectin protein on the microvascular endothelium is essential for the initial upregulation of the inflammatory response occurring in hemorrhagic shock. Moreover, endogenous levels of PSGL-1 mRNA were significantly increased in the lung, liver, and small intestine of wild-type mice subjected to hemorrhagic shock. Since PSGL-1 promotes adhesive interactions largely through P-selectin expressed on the vascular endothelium, this result further supports the crucial role played by P-selectin in the recruitment of leukocytes during hemorrhagic shock.
The Nuclear Factor of Activated T Cells (Nfat) Transcription Factor Nfatp (Nfatc2) Is a Repressor of Chondrogenesis
Authors: Ranger Ann M. , Gerstenfeld Louis C. , Wang Jinxi , Kon Tamiyo , Bae Hyunsu , Gravallese Ellen M. , Glimcher Melvin J. , Glimcher Laurie H.
Published: July 2002

Nuclear factor of activated T cells (NFAT) transcription factors regulate gene expression in lymphocytes and control cardiac valve formation. Here, we report that NFATp regulates chondrogenesis in the adult animal. In mice lacking NFATp, resident cells in the extraarticular connective tissues spontaneously differentiate to cartilage. These cartilage cells progressively differentiate and the tissue undergoes endochondral ossification, recapitulating the development of endochondral bone. Proliferation of already existing articular cartilage cells also occurs in some older animals. At both sites, neoplastic changes in the cartilage cells occur. Consistent with these data, NFATp expression is regulated in mesenchymal stem cells induced to differentiate along a chondrogenic pathway. Lack of NFATp in articular cartilage cells results in increased expression of cartilage markers, whereas overexpression of NFATp in cartilage cell lines extinguishes the cartilage phenotype. Thus, NFATp is a repressor of cartilage cell growth and differentiation and also has the properties of a tumor suppressor.
Antigen-Independent Appearance of Recombination Activating Gene (Rag)-Positive Bone Marrow B Cells in the Spleens of Immunized Mice
Authors: Gärtner Frank , Alt Frederick W. , Monroe Robert J. , Seidl Katherine J.
Published: July 2002

Splenic B lineage cells expressing recombination activation genes (RAG+) in mice immunized with 4-hydroxy-3-nitrophenyl-acetyl coupled to chicken γ-globulin (NP-CGG) and the adjuvant aluminum-hydroxide (alum) have been proposed to be mature B cells that reexpress RAG after an antigen encounter in the germinal center (GC), a notion supported by findings of RAG expression in peripheral B lymphocyte populations activated in vitro. However, recent studies indicate that these cells might be immature B cells that have not yet extinguished RAG expression. Here, we employ RAG2–green fluorescent protein (GFP) fusion gene knock-in mice to show that RAG+ B lineage cells do appear in the spleen after the administration of alum alone, and that their appearance is independent of T cell interactions via the CD40 pathway. Moreover, splenic RAG+ B lineage cells were detectable in immunized RAG2-deficient mice adoptively transferred with bone marrow (BM) cells, but not with spleen cells from RAG+ mice. Although splenic RAG+ B cells express surface markers associated with GC B cells, we also find the same basic markers on progenitor/precursor BM B cells. Finally, we did not detect RAG gene expression after the in vitro stimulation of splenic RAG− mature B cells with mitogens (lipopolysaccharide and anti-CD40) and cytokines (interleukin [IL]-4 and IL-7). Together, our studies indicate that RAG+ B lineage cells from BM accumulate in the spleen after immunization, and that this accumulation is not the result of an antigen-specific response.
The Hausdorff dimension of the Smale-Williams solenoid with different contraction coefficients
Authors: Simon Károly
Published: July 2002

In this paper we prove that the Hausdorff dimension of the Smale-Williams solenoid

Λ
¯

\overline {\Lambda }

with different contraction coefficients

λ
,
μ

\lambda ,\mu

is given by the formula
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="dimension Subscript upper H Baseline left-parenthesis normal upper Lamda overbar right-parenthesis equals 1 plus StartFraction log 2 Over log left-parenthesis 1 slash max left-parenthesis lamda comma mu right-parenthesis right-parenthesis EndFraction">

dim
H

⁡
(

Λ
¯

)
=
1
+

log
⁡
2

log
⁡
(
1

/

max
(
λ
,
μ
)
)

\dim _H(\overline {\Lambda })=1+\frac {\log 2}{\log (1/\max (\lambda ,\mu ))}

. Further, for

λ
,
μ
>

1
8

\lambda ,\mu >\frac 18

we prove that the Hausdorff dimension of each angular section is equal to

log
⁡
2

log
⁡
(
1

/

max
(
λ
,
μ
)
)

\frac {\log 2}{\log (1/\max (\lambda ,\mu ))}

.
On arithmetic Macaulayfication of Noetherian rings
Authors: Kawasaki Takesi
Published: July 2002

The Rees algebra is the homogeneous coordinate ring of a blowing-up. The present paper gives a necessary and sufficient condition for a Noetherian local ring to have a Cohen-Macaulay Rees algebra: A Noetherian local ring has a Cohen-Macaulay Rees algebra if and only if it is unmixed and all the formal fibers of it are Cohen-Macaulay. As a consequence of it, we characterize a homomorphic image of a Cohen-Macaulay local ring. For non-local rings, this paper gives only a sufficient condition. By using it, however, we obtain the affirmative answer to Sharp’s conjecture. That is, a Noetherian ring having a dualizing complex is a homomorphic image of a finite-dimensional Gorenstein ring.
Orbits and lattices for linear random number generators with composite moduli
Authors: Couture Raymond , L’Ecuyer Pierre
Published: July 2002

In order to analyze certain types of combinations of multiple recursive linear congruential generators (MRGs), we introduce a generalized spectral test. We show how to apply the test in large dimensions by a recursive procedure based on the fact that such combinations are subgenerators of other MRGs with composite moduli. We illustrate this with the well-known RANMAR generator. We also design an algorithm generalizing the procedure to arbitrary random number generators.
The Rabin-Monier theorem for Lucas pseudoprimes
Authors: Arnault F.
Published: July 2002

We give bounds on the number of pairs

(
P
,
Q
)

(P,Q)

with

0
≤
P
,
Q
>
n

0\le P,Q>n

such that a composite number

n
n

is a strong Lucas pseudoprime with respect to the parameters

(
P
,
Q
)

(P,Q)

.
A least-squares approach based on a discrete minus one inner product for first order systems
Authors: Bramble James , Lazarov Raytcho , Pasciak Joseph
Published: July 2002

The purpose of this paper is to develop and analyze a least-squares approximation to a first order system. The first order system represents a reformulation of a second order elliptic boundary value problem which may be indefinite and/or nonsymmetric. The approach taken here is novel in that the least-squares functional employed involves a discrete inner product which is related to the inner product in

H

−
1

(
Ω
)

H^{-1}(\Omega )

(the Sobolev space of order minus one on

Ω
\Omega

). The use of this inner product results in a method of approximation which is optimal with respect to the required regularity as well as the order of approximation even when applied to problems with low regularity solutions. In addition, the discrete system of equations which needs to be solved in order to compute the resulting approximation is easily preconditioned, thus providing an efficient method for solving the algebraic equations. The preconditioner for this discrete system only requires the construction of preconditioners for standard second order problems, a task which is well understood.
Dynamics of shift-like polynomial diffeomorphisms of 𝐶^{𝑁}
Authors: Bedford Eric , Pambuccian Victoria
Published: July 2002

We identify a family of polynomial diffeomorphisms ofCN{\mathbf C}^Nand show that these mappings may be studied using certain methods (filtration and potential-theoretic) which were developed for the study of polynomial diffeomorphisms ofC2{\mathbf C}^2.
GCUA: general codon usage analysis.
Authors: McInerney J O
Published: July 2002

SUMMARY: The program General Codon Usage Analysis (GCUA) has been developed for analysing codon and amino acid usage patterns. AVAILABILITY: ftp://ftp.nhm.ac.uk/pub/gcua. Freely available for academic use, commercial users should contact the author. CONTACT: J.McInerney@nhm.ac.uk
Evidence for coupling of membrane targeting and function of the signal recognition particle (SRP) receptor FtsY
Authors: Herskovits Anat A , Seluanov Andrei , Rajsbaum Ricardo , ten Hagen‐Jongman Corinne M , Henrichs Tanja , Bochkareva Elena S , Phillips Gregory J , Probst Francis J , Nakae Taiji , Ehrmann Michael , Luirink Joen , Bibi Eitan
Published: July 2002

Recent studies have indicated that FtsY, the signal recognition particle receptor of Escherichia coli, plays a central role in membrane protein biogenesis. For proper function, FtsY must be targeted to the membrane, but its membrane‐targeting pathway is unknown. We investigated the relationship between targeting and function of FtsY in vivo, by separating its catalytic domain (NG) from its putative targeting domain (A) by three means: expression of split ftsY, insertion of various spacers between A and NG, and separation of A and NG by in vivo proteolysis. Proteolytic separation of A and NG does not abolish function, whereas separation by long linkers or expression of split ftsY is detrimental. We propose that proteolytic cleavage of FtsY occurs after completion of co‐translational targeting and assembly of NG. In contrast, separation by other means may interrupt proper synchronization of co‐translational targeting and membrane assembly of NG. The co‐translational interaction of FtsY with the membrane was confirmed by in vitro experiments.
Mitochondrial Sequence Diversity Within a Subspecies of Savanna Monkeys (Cercopithecus aethiops) Is Similar to That Between Subspecies
Authors: Shimada M. K. , Terao K. , Shotake T.
Published: July 2002

Cercopithecus aethiops can be classified into four subspecies by morphology and by geographic distribution. However, the phylogenetic relationship between these subspecies is unclear. We previously found five distinct haplogroups of mitochondrial DNA (mtDNA) in the subspecies C. aethiops aethiops at the restriction fragment length polymorphism (RFLP) level, and found that those haplogroups are parapatrically distributed in their habitat. To determine the relationship between subspeciation and haplogroup formation in a subspecies, we compared mtDNA control region and 12S rRNA gene sequences (approximately 700 bp) in C. a. aethiops, two other subspecies of C. aethiops, and two species of Cercopithecus. The diversity between haplogroups in C. a. aethiops was almost the same as that between subspecies. This similar level of diversification between and within haplogroups may explain why a previously obtained mtDNA tree did not show monophyletic branching according to subspecies.
Base-compositional biases and the bat problem. II. DNA-hybridization trees based on AT- and GC-enriched tracers
Authors: Kirsch John A. W. , Pettigrew John D.
Published: July 2002

We did a series of parallel DNA–hybridization experiments on a small group of bats (species ofPteropus,Rhinolophus,Noctilio, andPteronotus) and outgroups (Lemur,Cynocephalus,Didelphis), using whole-genome labels and tracers made from extracts enriched for AT– and two levels of GC–content. FITCH topologies were constructed from the four sets of comparisons, indexed as both δTmodeand δNPHs (normalized percentage of hybridization). Based on our previous work showing that the shared AT–bias of pteropodids and some microchiropterans may affect the rank–ordering of taxa based on either AT– or GC–rich labels, our expectation was that the resulting trees would show differing topologies when generated from tracers made with the variously enriched DNA extracts. Whereas there was some variation among the trees, most of them grouped the bats together, and almost all paired the representative megachiropteran and rhinolophoid microchiropteran as sister–taxa in contrast to the other microchiropterans. As the pteropodid–rhinolophoid relationship is an unexpected and unlikely one, we attribute this association to an AT–bias that was not obviated even by our most GC–rich labels, and suggest that such a bias may compromise the truth of some molecular trees. Accordingly, we believe the broader issue of bat monophyly remains unresolved by DNA–hybridization and probably also by gene–sequencing studies.
Neural network for female mate preference, trained by a genetic algorithm
Authors: Kamo Masashi , Kubo Takuya , Iwasa Yoh
Published: July 2002

In some animals, males evolve exaggerated traits (e.g. the peacock's conspicuous tail and display) because of female preference. Recently Enquist and Arak presented a simple neural network model for a visual system in female birds that acquires the ability to discriminate males of the correct species from those of the wrong species by training. They reported that the trained networks were attracted by ‘supernormal stimuli’ where there was a greater response to an exaggerated form than to the images used as the correct species for training. They suggested that signal recognition mechanisms have an inevitable bias in response, which in turn causes selection on signal form. We here examine the Enquist and Arak model in detail. A three-layered neural network is used to represent the female's mate preference, which consists of 6 by 6 receptor cells arranged on a regular square lattice, ten hidden cells, and one output cell. Connection weights of the network were modified by a genetic algorithm, in which the female's fitness increases if she accepts a conspecific male but decreases if she accepts a male of a different species or a random image. We found that: (i) after the training period the evolved network was able to discriminate male images. Female preference evolves to favour unfamiliar patterns if they are similar to the images of the correct species (generalization); (ii) the speed and the final degree of learning depended critically on the choice of the random images that are rejected. The learning was much less successful if the random images were changed every generation than if 20 random images were fixed throughout the training period; (iii) the male of the same species used for training achieved the highest probability of being accepted by the trained network. Hence, contrary to Enquist and Arak, the evolved network was not attracted by supernormal stimuli.
The coelotrich: form and function of an unusual sensillum inLowrya(Ostracoda: Myodocopina: Cypridinidae)
Authors: Parker Andrew R.
Published: July 2002

This study reports a previously undescribed and unique sensillum. Some species ofLowryaParker 1998 (Ostracoda: Cypridinidae) possess sensillae of an unusual type arranged in a single row parallel to, and near, the anterior, ventral and posterior margins of the external surface of each carapace valve. These sensilla are here termed coelotrichs, and are each centred within an almost spherical cavity in the carapace. The cavity forms at the base of a depression, and the depression in turn lies within a sunken channel on the exterior carapace surface. The opening of the coelotrich cavity bears a ‘plug’, through which only the widened, divided base of a seta passes. The seta is very fine and stiff throughout most of its length, and exhibits no pores. For most of its length the seta is orientated parallel to the carapace surface, shielded within the sunken channel. The coelotrich is probably a velocity detector, acted upon by the viscous drag of the surrounding fluid. Its function is probably to detect vibrations in the substrate, such as acoustic motion in the surrounding liquid, or steady fluid drainage motion.
Deactivation, recovery from inactivation, and modulation of extra–synaptic ion currents in fish retinal ganglion cells
Authors: Ishida A.T.
Published: July 2002

As is shown magnificently by Heron Island's reef, the visual environment of many fishes includes various light intensities, hues and shapes that can change on large and small scales in space and time. Several articles in this issue address why fishes are sensitive to some of these properties, and how fishes and other aquatic species have acquired or fostered these sensitivities. This article discusses contributions of extrasynaptic ion currents, in a specific population of neurons, to the detection of ambient light levels, the appearance of certain visual stimuli and the disappearance of others.
Implementing multiple static field delivery for intensity modulated beams
Authors: Wu Y. , Yan D. , Sharpe M. B. , Miller B. , Wong J. W.
Published: July 2002

A clinically oriented two‐dimensional intensity‐modulated beam delivery method is implemented using multiple static segmented fields, i.e., the “step‐and‐shoot” approach. Starting with a desired “ideal” intensity distribution, it creates a multiple‐level intensity approximation, and then constructs a sequence of segmented fields to deliver the multiple‐level intensities using multileaf collimator (MLC) and independent backup jaws. The approach starts with a simple grouping of all the nonzero intensity values into a minimum number of clusters for a user specified deviation tolerance for the ideal plan. The k‐means clustering algorithm is then employed to find the optimal levels of intensity that minimize the discrepancies between the ideal and the approximated intensities, without violating the user specified deviation tolerance. The multiple‐level intensities are then decomposed into a sequence of machine deliverable segments. Apart from the first segment for each gantry angle, all the other segments are arranged to minimize the total travel distance of the leaves. The first segment covers the entire irradiated area and is used for treatment verification by electronic portal imaging. The implementation issues due to the physical constraints of the MLCs are also addressed.
Differences in wedge factor determination in air using a PMMA mini‐phantom or a brass build‐up cap
Authors: Heukelom S. , Lanson J. H. , Mijnheer B. J.
Published: July 2002

The head scatter dose contribution to the output of a treatment machine has been determined for an open and wedged gamma‐ray beam and for open and wedged x‐ray beams of 4, 8, and 16 MV. From those data wedge factor values “in air” have been deduced, expressed as the ratio of the dose to water, measured in air, for the situation with and without wedge, for the same number of monitor units (or treatment time for ). The measurements have been performed using a polymethylmetacrylate (PMMA) and a graphite‐walled ionization chamber inserted in a brass build‐up cap and in a PMMA mini‐phantom, respectively. Absolute wedge factor values deduced with both detector systems and based on the ratio of ionization chamber readings, differ for the investigated photon beams, up to 3.5% for the 4 MV x‐ray beam. The deviations result from the difference in composition between the detector materials and water and can be taken into account by conversion of the ionization chamber readings for both the open and wedged photon beams to the absorbed dose to water. For the brass build‐up cap detector system the ratio of the conversion factors for the wedged and open beam changes the ratio of the ionization chamber readings up to about 3.6% for the 4 MV x‐ray beam. For the mini‐phantom the conversion factors for the wedged and open beam are almost equal for all photon beams. Consequently, for that system wedge factors based on ionization chamber readings or dose values are the same. With respect to the wedge factor variation with field size a somewhat larger increase has been determined for the and 4 MV photon beam using the brass build‐up cap: about 1% for field sizes varying between and This effect has to be related to an apparent more pronounced variation of the head scatter dose contribution with field size for the wedged photon beams if the brass build‐up cap detection system is used. It can be concluded that determination of wedge factors “in air” under reference irradiation conditions, performed with both the mini‐phantom and brass build‐up cap yields within 0.5% the same result if the wedge factors are based on a dose to water ratio. However, by using high‐Z build‐up materials the determination is more complicated because appropriate conversion factors are then required, while similar conversion factors can be ignored if more water equivalent build‐up materials such as PMMA are applied.
Dosimetric evaluation of a widely used kilovoltage x‐ray unit for endocavitary radiotherapy
Authors: Li X. Allen , Ma C.‐M. , Salhani D. , Agboola O.
Published: July 2002

In this paper we present the dosimetric data of a Therapax DTX300 kilovoltage x‐ray unit for endocavitary rectal irradiation. The unit if operated at tube voltage of 40–60 kVp (30 mA) with an added filtration of 0.2–0.4 mm Al generates acceptable beam qualities comparable to those of the original Papillon technique. Relative dosimetric measurements were performed at the cone end (37.2 cm SSD) of a 3 cm diameter rectal cone using various detectors to ensure the accuracy. A Monte Carlo method was used to calculate correction factors for the diode used in the percentage depth‐dose (PDD) measurement, and to study the effect of the detector size on the beam profile. The PDD data were determined using the diode measurement corrected for its energy and angular response. It was found that the PTW N23342 and Markus parallel‐plate chamber can be used directly to measure the PDD for this beam quality with 2% uncertainty. Measurement and Monte Carlo results have shown that the detector size has a significant effect on the penumbral profile. Film and diode detectors have a better spatial resolution compared to ionization chambers, but they may give an incorrect profile tail due to either nonlinear response at low energy or angular dependence. This can be corrected using the ionization‐chamber measurement, based on the Monte Carlo analysis. The isodose distributions for this x‐ray unit are presented.
Oscillation of membranes using computer algebra
Authors: Portugal R. , Golebiowski L. , Frenkel D.
Published: July 2002

This paper presents a computer algebra application to the analysis of the membrane problem. Through animated displays, we present the movement of the axially symmetric normal modes of a circular membrane attached along its boundary, as well as the evolution due to initial conditions. The examples presented can be used as an in-class application of computer algebra systems in undergraduate courses like Mathematical Methods.
A study of sentence stress production in Mandarin speakers of American English
Authors: Chen Yang , Robb Michael P. , Gilbert Harvey R. , Lerman Jay W.
Published: July 2002

Acoustic characteristics of American English sentence stress produced by native Mandarin speakers are reported. Fundamental frequency (F0), vowel duration, and vowel intensity in the sentence-level stress produced by 40 Mandarin speakers were compared to those of 40 American English speakers. Results obtained from two methods of stress calculation indicated that Mandarin speakers of American English are able to differentiate stressed and unstressed words according to features of F0, duration, and intensity. Although the group of Mandarin speakers were able to signal stress in their sentence productions, the acoustic characteristics of stress were not identical to the American speakers. Mandarin speakers were found to produce stressed words with a significantly higher F0 and shorter duration compared to the American speakers. The groups also differed in production of unstressed words with Mandarin speakers using a higher F0 and greater intensity compared to American speakers. Although the acoustic differences observed may reflect an interference of L1 Mandarin in the production of L2 American English, the outcome of this study suggests no critical divergence between these speakers in the way they implement American English sentence stress.
Acoustic propagation through anisotropic internal wave fields: Transmission loss, cross-range coherence, and horizontal refraction
Authors: Oba Roger , Finette Steven
Published: July 2002

Results of a computer simulation study are presented for acoustic propagation in a shallow water, anisotropic ocean environment. The water column is characterized by random volume fluctuations in the sound speed field that are induced by internal gravity waves, and this variability is superimposed on a dominant summer thermocline. Both the internal wave field and resulting sound speed perturbations are represented in three-dimensional (3D) space and evolve in time. The isopycnal displacements consist of two components: a spatially diffuse, horizontally isotropic component and a spatially localized contribution from an undular bore (i.e., a solitary wave packet or solibore) that exhibits horizontal (azimuthal) anisotropy. An acoustic field is propagated through this waveguide using a 3D parabolic equation code based on differential operators representing wide-angle coverage in elevation and narrow-angle coverage in azimuth. Transmission loss is evaluated both for fixed time snapshots of the environment and as a function of time over an ordered set of snapshots which represent the time-evolving sound speed distribution. Horizontal acoustic coherence, also known as transverse or cross-range coherence, is estimated for horizontally separated points in the direction normal to the source–receiver orientation. Both transmission loss and spatial coherence are computed at acoustic frequencies 200 and 400 Hz for ranges extending to 10 km, a cross-range of 1 km, and a water depth of 68 m. Azimuthal filtering of the propagated field occurs for this environment, with the strongest variations appearing when propagation is parallel to the solitary wave depressions of the thermocline. A large anisotropic degradation in horizontal coherence occurs under the same conditions. Horizontal refraction of the acoustic wave front is responsible for the degradation, as demonstrated by an energy gradient analysis of in-plane and out-of-plane energy transfer. The solitary wave packet is interpreted as a nonstationary oceanographic waveguide within the water column, preferentially funneling acoustic energy between the thermocline depressions.
Mode function extraction from a VLA using singular value decomposition
Authors: Neilsen Tracianne B. , Westwood Evan K. , Udagawa Takeshi
Published: July 2002

A method is developed for extracting the depth-dependent mode functions from single-frequency measurements on a vertical line array as a source moves out in range. A matrix of the complex pressure field versus receiver depth and source range is formed, and the cross-spectral density matrix (CSDM) is computed. A singular value decomposition (SVD) is performed on the CSDM to obtain the orthonormal eigenvectors and the eigenvalues. Rearrangement of the normal mode equations reveals that under ideal conditions, the eigenvectors correspond to the mode functions and the eigenvalues are proportional to the modal source excitation and wave number. When two or more eigenvalues are nearly equal, the eigenvectors are not unique, and the correct mode functions are linear combinations of the eigenvectors. Other complications arise when the pressure field is not sampled adequately in depth or range. The procedure is applied to simulated data for a Pekeris waveguide and a realistic geoacoustic profile. Extracted mode functions from sources of opportunity are intended to be used for geoacoustic inversion of the sound-speed profile and bottom properties. [Work supported by the U. S. Army Research Office, AASERT Grant No. DAAH04-95-1-0486, and ONR.]
Effects of language experience on speech perception
Authors: Kuhl Patricia K.
Published: July 2002

Language experience during the first year of life has a dramatic effect on infants’ perception and production of speech. In this presentation, (a) studies of cross-language effects of language experience on consonant and vowel perception, (b) studies of the effects of speech experience on infants’ vowel production, and (c) infant Mismatched Negativity (MMN) responses for speech will be used to show that language experience causes infants to ignore physical differences between speech stimuli that are irrelevant in their native language. A theory is offered to explain how early language experience alters speech perception. The theory holds that listening to native-language speech causes infants to develop ‘‘perceptual maps’’ of the incoming speech information. These maps functionally alter the perceived distances between physical stimuli. [Work supported by NIH.]
Role of experience for language-specific functional mappings of vowel sounds
Authors: Kluender Keith R. , Lotto Andrew J. , Holt Lori L. , Bloedel Suzi L.
Published: July 2002

Studies involving human infants and monkeys suggest that experience plays a critical role in modifying how subjects respond to vowel sounds between and within phonemic classes. Experiments with human listeners were conducted to establish appropriate stimulus materials. Then, eight European starlings (Sturnus vulgaris) were trained to respond differentially to vowel tokens drawn from stylized distributions for the English vowels /i/ and /ɪ/, or from two distributions of vowel sounds that were orthogonal in the F1–F2 plane. Following training, starlings’ responses generalized with facility to novel stimuli drawn from these distributions. Responses could be predicted well on the bases of frequencies of the first two formants and distributional characteristics of experienced vowel sounds with a graded structure about the central “prototypical” vowel of the training distributions. Starling responses corresponded closely to adult human judgments of “goodness” for English vowel sounds. Finally, a simple linear association network model trained with vowels drawn from the avian training set provided a good account for the data. Findings suggest that little more than sensitivity to statistical regularities of language input (probability–density distributions) together with organizational processes that serve to enhance distinctiveness may accommodate much of what is known about the functional equivalence of vowel sounds.
Does echolocation wavelength restrict bats’ choice of prey?
Authors: Houston Robert D. , Boonman Arjan M. , Jones Gareth
Published: July 2002

The size range of insects encountered by bats that use narrowband echolocation signals (FM-CF or quasi-CF) extends to sizes much smaller than the wavelengths used by these bat species. It was hypothesized that the expected Rayleigh scattering sets a lower limit on the size of prey which can be detected. To test the Rayleigh scattering theory empirically, insects were ensonified with pure-tone pulses ranging from 20 to 85 kHz and their target strengths were measured. The target strength of the smaller insects was frequency-dependent within the frequency range used by aerial-hawking bats. The target strength diminished sharply as the wing length to wavelength ratio decreased below unity. A model was developed to predict maximum detection distances, which lead to an estimate of the optimum frequency to be used for detecting each insect size. In a dietary analysis, it was found that the bat species using the shortest wavelengths took the smallest insects. The minimum prey size detectable by each bat species was predicted. The longest wavelength bats (Vespertilio murinus, Nyctalus noctula) took smaller prey than were estimated. The diets of the shorter wavelength bats agreed with predictions of the model. [Work supported by BBSRC.]
An axisymmetric poroelastic finite element formulation
Authors: Kang Yeon June , Gardner Bryce K. , Bolton J. Stuart
Published: July 2002

In the past, various two- and three-dimensional Cartesian, poroelastic finite element formulations have been proposed and demonstrated. Here an axisymmetric formulation of a poroelastic finite element is presented. The intention of this work was to develop a finite element formulation that could easily and efficiently model axisymmetric sound propagation in circular structures having arbitrary, axially dependent radii, and that are lined or filled with elastic porous sound absorbing materials such as foams. The formulation starts from the Biot equations for an elastic porous material expressed explicitly in axisymmetric form. By following a standard finite element development, a u-U formulation results. Procedures for coupling the axisymmetric elements to an adjacent acoustical domain are described, as are the boundary conditions appropriate for unfaced foams. Calculations described here show that the present formulation yields predictions as accurate as a Cartesian, three-dimensional model in much reduced time. Predictions made using the present model are also compared with measurements of sound transmission through cylindrical foam plugs, and the predicted results are shown to agree well with the measurements. Good agreement was also found in the case of sound transmission through a conical foam plug.
Particle Motions in Non-Newtonian Media. II. Poiseuille Flow
Authors: Gauthier F. , Goldsmith H. L. , Mason S. G.
Published: July 2002

The behavior of rigid and deformable particles suspended in pseudoplastic and elasticoviscous liquids undergoing tube flow was studied. The velocity profiles were more blunted than those obtained for Newtonian fluids and, as in Couette flow, the measured angular velocities of rigid spheres, rods, and discs were in accord with the theory for Newtonian liquids. There was also a drift in the orbit of the cylinders to limiting values corresponding to minimum energy dissipation in the flow. In elasticoviscous liquids, rigid particles migrated across the planes of shear towards the tube axis whereas in pseudoplastic liquids, the opposite was observed, rigid spheres actually coming in contact with the wall. The lateral migration of deformed liquid drops in elasticoviscous fluids was, as in Newtonian systems, towards the tube axis whereas in pseudoplastic liquids the drops attained an equilibrium position between the tube wall and axis. An accumulation of rigid spheres behind an advancing suspension-air meniscus was observed in elasticoviscous media at all initial volume concentrations, the rates of accumulation increasing with flow rate and particle size. In the pseudoplastic fluids, however, there was a dilution at concentrations less than 10% followed by an accumulation at higher values but the rates of accumulation decreased with increasing flow rate and particle size. As in the Couette flow of non-Newtonian suspension, it was not possible to interpret the observed radial migration of the particles in terms of the known rheological properties of the suspending fluids.
Secondary and Primary Normal Stresses, Hole Error, and Reservoir Edge Effects in Cone-and-Plate Flow of Polymer Solutions
Authors: Olabisi Olagoke , Williams Michael C.
Published: July 2002

Pressure profiles πψψ(r) were obtained for several polymer solutions in a cone-and-plate device (R=10 in., ψ0=1.5°) over a shear rate range 7–266 sec−1. Measurements were made with a single transducer mounted flush with a movable plate; the transducer could also be lowered to simulate the effect of holes. Normal stress functions N1=π11−π22 and N2=π22−π33 were calculated by four different methods, representing varying approximations to the real πψψ(r) distribution. For polyethylene oxide (PEO) in water/glycerin and polystyrene (PS) in Aroclor, N2/N1 was found to be negative and greater in magnitude for the latter system. The function |N2/N1| for PEO appeared nearly constant over most of the shear range, although possibly increasing below 30 sec−1. Values for PS did not achieve this asymptotic condition, but were consistent with such behavior. Magnitude of the asymptote for PEO was 0.1–0.2, depending on the method of calculation. Simulated pressure tap holes caused lower πψψ, leading to N1 values reduced by as much as 30% and totally misleading N2. The holes are thus shown to be responsible for the commonly reported positive values of N2/N1.
Numerical Calculations of the Viscoelastic Properties of Dilute Solutions of Comb-Shaped Branched Polymers
Authors: Osaki Kunihiro , Mitsuda Yutaka , Schrag John L. , Ferry John D.
Published: July 2002

The viscoelastic properties of dilute solutions of comb-shaped branched polymers have been calculated from the bead-spring model, following the Zimm and Zimm-Kilb theories, with exact numerical evaluation of eigenvalues by the method of Lodge and Wu. Eigenvalues, relaxation times, and frequency dependence of the reduced intrinsic shear moduli [G′]R and [G″]R have been obtained for various combinations of number of branch points (f) 1 to 10, beads per branch (Nb) 1 to 37, backbone beads between branches (Na) 1 to 22, and the reduced hydrodynamic interaction parameter (h*) 0 to 0.25. Since the total number of beads (f+1) Na+fNa+fNb−1 is restricted to an unrealistically small value of 111 by computer limitations, attention is focused on the low-frequency behavior where this restriction will have the least influence. Here, the behavior is characterized by the reduced steady-state shear compliance. This quantity is quite sensitive to f when the mass backbone fraction λ is small (approaching starshaped geometry); and for larger λ, it can detect the presence of a small number of branches.
Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting
Authors: Neuser Moritz , Kappe Fabian , Ostermeier Jakob , Krüger Jan Tobias , Bobbert Mathias , Meschut Gerson , Schaper Mirko , Grydin Olexandr
Published: August 2022

AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks during joint formation when mechanical joining technologies are used. A rise in ductility can be achieved by a considerable increase in the solidification rate which results in grain refinement. High solidification rates can be realized in twin–roll casting (TRC) by water‐cooled rolls. Therefore, a hypoeutectic EN AC–AlSi9 (for European Norm ‐ aluminum cast product) is manufactured by the TRC process and analyzed. Subsequently, joining investigations are performed on castings in as‐cast and heat‐treated condition using the self‐piercing riveting process considering the joint formation and the load‐bearing capacity. Due to the fine microstructure, the crack initiation can be avoided during joining, while maintaining the joining parameters, especially by specimens in heat treatment conditions. Furthermore, due to the extremely fine microstructure, the load‐bearing capacity of the joint can be significantly increased in terms of the maximum load‐bearing force and the energy absorbed.
Antiferromagnetic–Ferromagnetic Heterostructure‐Based Field‐Free Terahertz Emitters
Authors: Wu Xiaojun , Wang Hanchen , Liu Haijiang , Wang Yizhan , Chen Xinhou , Chen Peng , Li Peiyan , Han Xiufeng , Miao Jungang , Yu Haiming , Wan Caihua , Zhao Jimin , Chen Sai
Published: August 2022

Recently, ferromagnetic‐heterostructure spintronic terahertz (THz) emitters have been recognized as one of the most promising candidates for next‐generation THz sources, owing to their peculiarities of high efficiency, high stability, low cost, ultrabroad bandwidth, controllable polarization, and high scalability. Despite the substantial efforts, they rely on external magnetic fields to initiate the spin‐to‐charge conversion, which hitherto greatly limits their proliferation as practical devices. Here, a unique antiferromagnetic–ferromagnetic (IrMn3|Co20Fe60B20) heterostructure is innovated, and it is demonstrated that it can efficiently generate THz radiation without any external magnetic field. It is assigned to the exchange bias or interfacial exchange coupling effect and enhanced anisotropy. By precisely balancing the exchange bias effect and enhanced THz radiation efficiency, an optimized 5.6 nm‐thick IrMn3|Co20Fe60B20|W trilayer heterostructure is successfully realized, yielding an intensity surpassing that of Pt|Co20Fe60B20|W. Moreover, the intensity of THz emission is further boosted by togethering the trilayer sample and bilayer sample. Besides, the THz polarization may be flexibly controlled by rotating the sample azimuthal angle, manifesting sophisticated active THz field manipulation capability. The field‐free coherent THz emission that is demonstrated here shines light on the development of spintronic THz optoelectronic devices.
Targeted organized teaching scripts (TOTS) in the pediatric emergency department
Authors: Sokoloff William C. , Kusulas Matthew P. , Cassara Michael
Published: August 2022

In the pediatric emergency department (PED), considerable challenges inhibit educational opportunities for residents outside of being precepted. The use of teaching scripts specifically addresses these challenges by allowing faculty to have prepared, hyperfocused content that can be delivered in a short time. We developed a series of teaching scripts for 10 high‐yield topics in the PED and assessed their effectiveness at improving educational experiences. Teaching scripts were inconsistently used but well received. Their use also correlated with increased resident satisfaction with clinical teaching. The majority of residents and faculty showed considerable interest in expanding the TOTS program to include additional pediatric emergency medicine topics.
An accurate fully automated panel of plasma biomarkers for Alzheimer's disease
Authors: Palmqvist Sebastian , Stomrud Erik , Cullen Nicholas , Janelidze Shorena , Manuilova Ekaterina , Jethwa Alexander , Bittner Tobias , Eichenlaub Udo , Suridjan Ivonne , Kollmorgen Gwendlyn , Riepe Matthias , von Arnim Christine A.F. , Tumani Hayrettin , Hager Klaus , Heidenreich Fedor , Mattsson‐Carlgren Niklas , Zetterberg Henrik , Blennow Kaj , Hansson Oskar
Published: August 2022

Introduction

There is a great need for fully automated plasma assays that can measure amyloid beta (Aβ) pathology and predict future Alzheimer's disease (AD) dementia.

Methods

Two cohorts (n = 920) were examined: Panel A+ (n = 32 cognitively unimpaired [CU], n = 106 mild cognitive impairment [MCI], and n = 89 AD) and BioFINDER‐1 (n = 461 CU, n = 232 MCI). Plasma Aβ42/Aβ40, phosphorylated tau (p‐tau)181, two p‐tau217 variants, ApoE4 protein, neurofilament light, and GFAP were measured using Elecsys prototype immunoassays.

Results

The best biomarker for discriminating Aβ‐positive versus Aβ‐negative participants was Aβ42/Aβ40 (are under the curve [AUC] 0.83–0.87). Combining Aβ42/Aβ40, p‐tau181, and ApoE4 improved the AUCs significantly (0.90 to 0.93; P< 0.01). Adding additional biomarkers had marginal effects (ΔAUC ≤0.01). In BioFINDER, p‐tau181, p‐tau217, and ApoE4 predicted AD dementia within 6 years in CU (AUC 0.88) and p‐tau181, p‐tau217, and Aβ42/Aβ40 in MCI (AUC 0.87).

Discussion

The high accuracies for Aβ pathology and future AD dementia using fully automated instruments are promising for implementing plasma biomarkers in clinical trials and clinical routine.
Construction of a novel double network polymer composite and evaluation of its highly efficient adsorption properties for copper ions
Authors: Wu Xiaoqiong , Song Yutong , Yin Ping , Xu Qiang , Yang Zhenglong , Xu Yanbin , Liu Xiguang , Wang Feng , Wang Ying , Sun Wenjuan , Cai Honglan
Published: August 2022

To explore more efficient heavy metal copper ions adsorbents with double network polymers, this work has presented the novel fabrication processes of the polymer composite diatomaceous earth/polydopamine‐polyethyleneimine/alginate DE@PDA‐PEI@SA, which was characterized by FT‐IR, SEM, EDS, XPS, and was efficiently utilized for copper ions adsorption. The relevant adsorption behaviors of DE@PDA‐PEI@SA for copper ions such as the effect of pH, the effect of adsorbent dosage, adsorption kinetics, adsorption isotherm etc. have been investigated. The results reveal that the adsorption kinetics of DE@PDA‐PEI@SA for copper ions at different temperatures can be modeled by the pseudo second‐order rate equation, the experimental data fit well with the Langmuir isotherm model, indicating a homogeneous monolayer adsorption, and the maximum adsorption capacity of DE@PDA‐PEI@SA for copper ions could reach 454.55 mg/g at 35°C that is very high compared to other reported adsorbent materials. The research results indicate that DE@PDA‐PEI@SA is a novel efficient adsorbent with high efficiency in wastewater treatment and water purification, which could provide a facile processing for copper adsorption.
Post‐Assembly Modification of Protein Cages by Ubc9‐Mediated Lysine Acylation
Authors: Levasseur Mikail D. , Hofmann Raphael , Edwardson Thomas G. W. , Hehn Svenja , Thanaburakorn Manutsawee , Bode Jeffrey W. , Hilvert Donald
Published: August 2022

Although viruses have been successfully repurposed as vaccines, antibiotics, and anticancer therapeutics, they also raise concerns regarding genome integration and immunogenicity. Virus‐like particles and non‐viral protein cages represent a potentially safer alternative but often lack desired functionality. Here, we investigated the utility of a new enzymatic bioconjugation method, called lysine acylation using conjugating enzymes (LACE), to chemoenzymatically modify protein cages. We equipped two structurally distinct protein capsules with a LACE‐reactive peptide tag and demonstrated their modification with diverse ligands. This modular approach combines the advantages of chemical conjugation and genetic fusion and allows for site‐specific modification with recombinant proteins as well as synthetic peptides with facile control of the extent of labeling. This strategy has the potential to fine‐tune protein containers of different shape and size by providing them with new properties that go beyond their biologically native functions.