Showing papers by "University of Notre Dame published in 1990"
TL;DR: Theoretical rationales for the robust empirical relationships between the share of intraindustry trade between two countries and the average levels of, and inequalities between, their GDPs, per capita GDPs and tariffs have either varied or not been demonstrated formally within a unified analytical framework.
Abstract: Theoretical rationales for the robust empirical relationships between the share of intraindustry trade between two countries and the average levels of, and inequalities between, their GDPs, per capita GDPs, and tariffs have either varied or not been demonstrated formally within a unified analytical framework. This study motivates theoretically the relationships between these six determinants, as well as the average level of, and inequality between, two countries' capital-labor endowment ratios and their share of intraindustry trade. Regression analysis supports, among other results, the presence of both demand and supply roles for per capita income influencing intraindustry trade. Copyright 1990 by Royal Economic Society.
677 citations
TL;DR: In this paper, a macroscopic thermodynamic theory was developed to describe two-phase flow in porous media, where the authors developed a constitutive theory resulting in balance equations and thermodynamics appropriate for modelling multiphase flow.
587 citations
TL;DR: A description is given of 11 papers from the April 1990 special issue on neural networks in control systems of IEEE Control Systems Magazine, on the design of associative memories using feedback neural networks and the modeling of nonlinear chemical systems using neural networks.
Abstract: A description is given of 11 papers from the April 1990 special issue on neural networks in control systems of IEEE Control Systems Magazine. The emphasis was on presenting as varied and current a picture as possible of the use of neural networks in control. The papers described cover: the design of associative memories using feedback neural networks; a method to use neural networks to control highly nonlinear systems; the modeling of nonlinear chemical systems using neural networks; the identification of dynamical systems; the comparison of conventional adaptive controllers and neural-network-based controllers; a method to provide adaptive control for nonlinear systems; neural networks and back-propagation; the back-propagation algorithm; the use of trained neural networks to regulate the pitch attitude of an underwater telerobot; the control of mobile robots; and the issues involved in integrating neural networks and knowledge-based systems. >
462 citations
TL;DR: In this paper, the Betti number of a smooth projective variety over C or over 1 is computed using the Weil conjectures and the Picard group of S tnl.
Abstract: Several authors have been interested in the Hilbert scheme SPq:=Hilb"(S) parametrizing finite subschemes of length n on a smooth projective surface S. In EF 1] and I-F 2] Fogarty shows that S tnj is smooth and there exists a natural birational morphism co n: St"J~S("). Here S (n) is the n th symmetric power of S. So S t"j is a natural desingularisation of S (n). He then computes the Picard group of S tnl. In I-I 1] the highest dimensional fiber Hilb"(spec(k[I-x, y]])) of co n is studied, and in I-I 2] it is shown, that the expectional locus of con is an irreducible divisor. Fujiki has shown in I-Fj] that S t2J is a symplectic variety, if S is a K 3 surface, thereby disproving a conjecture of Bogomolov. In [B] Beauville generalizes this result to arbitrary n. Several authors have worked on the eohomology of St*J: The ease n___ 2 is trivial by the results of IF 2]. The homology groups of Hilb3(P2) have been computed in I-H]. Finally in [E-S] the homology groups of Hilbn(P2), Hilbn(A2), Hilb"(spee(k[[x,y]])), and Hilb~(27m) are computed. Here P2 is the projective plane, A 2 is the attine plane and Zm is the mth Hirzebruch surface. In this paper we will compute the Betti numbers ofS t"j for an arbitrary smooth surface S using the Weil conjectures. We want to state our main result: Let F+ be a finite field with q elements, l~a its algebraic closure. Let X be a smooth projective variety over C or over 1~.. In the first case let b~(X) be the i th Betti number of X. In the second ease let b+(X) ~ the rank of the i th l-adic cohomology group Hi(X, Ql) of X. In both eases let p(X, z) be the Poinear6 polynomial ~ b+(X)z + of X and e(X): = ~ (-1)/b,~X) the i t Euler number of X. We put ~X, z): = p ( X , z ) .
433 citations
01 May 1990
TL;DR: The AMUSE algorithm is derived on the basis of the necessary condition of source identifiability and shown to have good performance and wide application.
Abstract: The mathematical formulation of the blind identification problem is presented. Various theoretical properties are discussed. The AMUSE algorithm is derived on the basis of the necessary condition of source identifiability and shown to have good performance and wide application. >
291 citations
TL;DR: A systematic approach to partitioning L*MPSK signal sets that is based on block coding is used and an encoder system approach is developed that incorporates the design of a differential precoder, a systematic convolutional encoder, and a signal set mapper.
Abstract: A 2L-dimensional multiple phase-shift keyed (L*MPSK) signal set is obtained by forming the Cartesian product of L two-dimensional MPSK signal sets. A systematic approach to partitioning L*MPSK signal sets that is based on block coding is used. An encoder system approach is developed. It incorporates the design of a differential precoder, a systematic convolutional encoder, and a signal set mapper. Trellis-coded L*4PSK, L*8PSK, and L*16PSK modulation schemes are found for 1 >
268 citations
TL;DR: This article examined the concurrent relationship between late adolescent attachment to parents and peers and two broad indices of adolescent adaptation, personal and social identity and adjustment to college, and found that women reported less alienation from peers, had more trust and better communication with peers, and had higher scores on personal idenitity than men.
Abstract: We examined the concurrent relationship between late adolescent attachment to parents and peers and two broad indices of adolescent adaptation—personal and social identity and adjustment to college. Participants included 130 college freshmen and 123 upperclassmen. Although freshmen were disadvantaged relative to upperclassmen with respect to social and personal-emotional adjustment, there were no group differences on the attachment measures, on the measures of academic adjustment and goal commitment, and on the measure of social identity. Freshmen scored higher on personal identity than did upperclassmen. Women reported less alienation from peers, had more trust and better communication with peers, and had higher scores on personal and social idenitity than men. The attachment variables were significant predictors of personal and social identity. Pervasive relations were also found between attachment and adjustment to college, particularly for the upperclassmen sample.
263 citations
TL;DR: Relation of depressive symptoms to social and academic competence was examined in 750 4th-grade students and stronger correlations than have previously been reported were found between depressive symptoms and both kinds of competence.
Abstract: Relation of depressive symptoms to social and academic competence was examined in 750 4th-grade students. Self-report, peer-nomination, and teacher-rating measures of all three constructs were obtained. The multitrait-multimethod data were examined with confirmatory factor analysis and multivariate analysis of variance. Stronger correlations than have previously been reported were found between depressive symptoms and both kinds of competence. Social and academic incompetence had an additive effect on depressive symptoms. Children who were both socially and academically less competent had more symptoms of depression than children who had only one problem area. Children with only one problem area had more symptoms of depression than did children who were neither socially nor academically less competent. Gender differences in other-rated measures of competence were also evident. Implications for a competency-based model of depression are discussed.
260 citations
TL;DR: Several design techniques that can be used for continuous-time and discrete-time neural networks to realize associative memories are presented and some stability concepts are outlined.
Abstract: Several design techniques that can be used for continuous-time and discrete-time neural networks to realize associative memories are presented. Associative memory is discussed, and neural network models are presented. Some stability concepts are outlined. The applicability of these techniques is demonstrated by means of specific examples that illustrate strengths and weaknesses. >
219 citations
TL;DR: In the years since the publication of Thomas Kuhn's Structure of Scientific Revolutions, the term "scientific revolution" has been used with increasing frequency in discussions of scientific change, and the magnitude required of an innovation before someone or other is tempted to call it a revolution has diminished alarmingly as discussed by the authors.
Abstract: In the years since the publication of Thomas Kuhn’s Structure of Scientific Revolutions, the term ‘scientific revolution’ has been used with increasing frequency in discussions of scientific change, and the magnitude required of an innovation before someone or other is tempted to call it a revolution has diminished alarmingly. Our thesis in this paper is that if a certain family of connectionist hypotheses turn out to be right, they will surely count as revolutionary, even on stringent pre-Kuhnian standards. There is no question that connectionism has already brought about major changes in the way many cognitive scientists conceive of cognition. However, as we see it, what makes certain kinds of connectionist models genuinely revolutionary is the support they lend to a thoroughgoing eliminativism about some of the central posits of common sense (or ‘folk’) psychology. Our focus in this paper will be on beliefs or propositional memories, though the argument generalizes straightforwardly to all the other propositional attitudes. If we are right, the consequences of this kind of connectionism extend well beyond the confines of cognitive science, since these models, if successful, will require a radical reorientation in the way we think about ourselves.
209 citations
TL;DR: In this article, the authors carried out an asymptotic analysis for different convective, diffusive and kinetic timescales and showed that, if transport in the film is mass-transfer limited such that a bulk concentration gradient exists, the film thickness increases by a maximum factor of 4 2/3; over Bretherton's mobile result at low bubble speeds.
Abstract: When a viscous liquid is displaced by a long air bubble in a capillary, it leaves behind a wetting liquid film. A lubrication analysis by Bretherton (1961), which assumes a mobile surface, underpredicts the film thickness at low bubble speeds. In this investigation, the Marangoni effect of small amounts of impurities is shown to be capable of explaining this discrepancy. We carry out an asymptotic analysis for different convective, diffusive and kinetic timescales and show that, if transport in the film is mass-transfer limited such that a bulk concentration gradient exists in the film, the film thickness increases by a maximum factor of 4 2/3; over Bretherton's mobile result at low bubble speeds. Moreover, at large bubble speeds, Bretherton's mobile prediction is approached for all ranges of timescales. For intermediate bubble speeds, the film thickness varies with respect to the bubble speed with an exponent smaller than 2/3 of the mobile theory. These results are favourably compared to literature data on film thickness.
TL;DR: A strong correlation was found between child depression and conduct disorder (D&CD) and peer social status (i.e., popular, rejected, neglected, controversial, average), and it was revealed that rejected Ss scored higher than average Ss on measures of D&CD.
Abstract: This study examined the overlap between child depression and conduct disorder (DC the other by symptoms of undercontrol, conduct disorder, aggression, delinquency, and hyperactivity (Achenbach, 1966, 1985; Achenbach & Edelbrock, 1978; Miller, 1967; Peterson, 1961; Quay, 1979; Rutter, 1976). However, a growing literature suggests that a substantial number of psychologically disturbed prepubertal children cannot be neatly classified by this dichotomous nomenclature. Rutter, Tizard, and Whitmore (1970) labeled this group "mixed disorders" and presented data suggesting that this category accounted for 21% of a large sample of disturbed children. Similarly, Edelbrock and Achenbach's (1980) study of clinically referred boys revealed a group of depressed, withdrawn, and aggressive children that constituted 7.6% of their sample. Several other studies have examined the prevalence of conduct disorder among depressed children. Puig-Antich (1982) noted that 37% of depressed boys also met Diagnostic and Statistical Manual of Mental Disorders (3rd ed., DSM-III; American Psychiatric Association, 1980) criteria for conduct disorder. Ko
01 Jun 1990
TL;DR: In this paper, a detailed review of the properties of DMS alloys is presented, focusing on materials of the type A/sub 1-x/sup II/ Mn/sub x/B/sup VI/ which are the most thoroughly understood.
Abstract: Diluted magnetic semiconductors (DMSs), i.e. semiconducting crystals whose lattice is made up in part of substitutional magnetic ions (e.g. Cd/sub 1-x/Mn/sub x/Te, Hg/sub 1-x/Fe/sub x/Se, Zn/sub 1-x/Co/sub x/S), are reviewed. The focus is on materials of the type A/sub 1-x//sup II/ Mn/sub x/B/sup VI/, which are the most thoroughly understood. However, the similarities and differences between these materials and the A/sub 1-x//sup II/Fe/sub x/B/sup VI/ and A/sub 1-//sup II/Co/sub x/B/sup VI/ systems are discussed wherever information on the latter system is available. The band structure of the materials, which determines their basic semiconducting properties, is examined. Special attention is given to exchange interactions between the magnetic ions themselves (the d-d interaction) and the interaction between the magnetic ions and band electrons (the sp-d interaction). Magnetic phenomena in DMS alloys are considered. Special attention is given to the physics of layered structures, such as quantum wells and superlattices, involving DMS materials. The prospects of device applications made possible by the properties of DMS alloys are assessed. >
TL;DR: In this paper, the authors defined the Reynolds number based on distance from leading edge (or chord) and freestream velocity, which is a measure of the amount of fluid being injected or withdrawn through a wall.
Abstract: Nomenclature CD = drag coefficient ( = 2D/pUlc) Cf = local skin-friction coefficient ( = 2rw/pUl) CL = lift coefficient ( = 2L/pU^c) Cq = suction coefficient ( = I vw I / UQ) c = airfoil's chord D = drag force per unit span L = lift force per unit span P = instantaneous hydrostatic pressure PO = pressure outside boundary layer P = mean pressure R = wall's radius of curvature /?6* = displacement thickness Reynolds number (= Uod*/v) RO = momentum thickness Reynolds number ( = U0de/v) Re = Reynolds number based on distance from leading edge (or chord) and freestream velocity T = instantaneous temperature T = mean temperature J7, = instantaneous velocity component Uj = mean velocity component U0 = velocity outside the boundary layer t/oo = freestream velocity HI = fluctuating velocity component u* = friction velocity ( = Vr^/p) vw = normal velocity of fluid injected or withdrawn through the wall X-, = Cartesian coordinates x = streamwise distance from leading edge y = normal distance from the wall y = normal distance in wall units ( = yu*/v) Z = spanwise coordinate a. = angle of attack 6 = boundary-layer thickness 60 = momentum thickness 6* = displacement thickness /x = dynamic coefficient of viscosity v = kinematic viscosity v/u * = viscous length scale (wall unit) p = density — p~uv = tangential Reynolds stress T.W = shear stress at the wall ( = pu *) [AJo = instantaneous spanwise vorticity at the wall _ [fijo = rnean spanwise vorticity at the wall (= — [dU/dy]Q)
TL;DR: The data indicate that both normal and alternate pathways exist in these cells for incorporation and trimming of high-mannose oligosaccharides and that mannosidases, as well as galactosyl-, hexosaminidasyl-, and sialyltransferases are present, and/or can be induced, in these Cells.
Abstract: A comparison has been made between the Asn289-linked oligosaccharide structures of human plasma plasminogen and a recombinant human plasminogen, expressed in lepidopteran insect (Spodoptera frugiperda) cells, after infection of these cells with a recombinant baculovirus containing the entire human plasminogen cDNA. Using anion-exchange liquid chromatography mapping of the oligosaccharide units cleaved from the proteins by glycopeptidase F, compared with elution positions of standard oligosaccharide structures, coupled with monosaccharide compositional analysis, we find that the human plasma protein contained only bisialo-biantennary complex-type carbohydrate and asialo-biantennary complex carbohydrate, confirming earlier work published by this laboratory. The glycosylation pattern of the insect cell expressed recombinant human plasminogen showed considerable microheterogeneity, with identifiable high-mannose carbohydrate (Man9GlcNAc2) and truncated high-mannose oligosaccharide (Man5GlcNAc2, Man4GlcNAc2, and Man3GlcNAc2). Of major importance, approximately 40% of the oligosaccharide population consisted of complex carbohydrate (bisialo-biantennary), identical in structure with that of the human plasma protein. This is the first direct identification of complex carbohydrate in proteins produced in insect cells and demonstrates that trimming and processing of high-mannose carbohydrate into complex-type oligosaccharide can occur. Our data indicate that both normal and alternate pathways exist in these cells for incorporation and trimming of high-mannose oligosaccharides and that mannosidases, as well as galactosyl-, hexosaminidasyl-, and sialyltransferases are present, and/or can be induced, in these cells. From these observations, we conclude that amino acid sequences and/or protein conformational properties can control oligosaccharide processing events.
TL;DR: In this article, the parity-nonconserving amplitude for the 6${\mathit{s}}{1/2}$\ensuremath{\rightarrow}7${ s}}_{1/ 2}$ transition in atomic cesium with an error of order 1% is presented.
Abstract: A many-body calculation of the parity-nonconserving amplitude for the 6${\mathit{s}}_{1/2}$\ensuremath{\rightarrow}7${\mathit{s}}_{1/2}$ transition in atomic cesium with an error of order 1% is presented, ${\mathit{E}}_{\mathrm{PNC}}$=-0.906[9] (${\mathit{Q}}_{\mathit{W}}$/-N)i\ensuremath{\Vert}e\ensuremath{\Vert}${\mathit{a}}_{0}$\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$. Using this result to determine ${\mathit{Q}}_{\mathit{W}}$ from high-precision measurements of the transition leads to a quantitative test of the standard model. The various sources contributing to this transition are discussed and their uncertainties estimated. A discussion of radiative corrections with emphasis on the role of the top-quark mass is given.
Journal Article•
TL;DR: The assertion was made that individuals with retardation are delayed in developing self-regulatory control because of their extensive language deficiencies, and both the essential components of the self-Regulatory system along with the environments that promote self-regulated behavior must be isolated.
Abstract: The educational and research implications of defining mental retardation as a self-regulatory disorder were explored. Behavioral, social-learning, and cognitive conceptualizations regarding the structure and development of self-regulation were examined. Emphasis was placed on showing how these conceptualizations compliment each other. Several perspectives were presented, specifically, that both the essential components of the self-regulatory system along with the environments that promote self-regulated behavior must be isolated. Self-regulation was described as a complex skill that develops like other skills and can be taught through behavioral techniques. Self-regulation was suggested to basically be a linguistically guided process. The assertion was made that individuals with retardation, because of their extensive language deficiencies, are delayed in developing self-regulatory control. The role of life experience and motivational processes in the development of self-regulation was also stressed.
TL;DR: In this paper, the epitaxial growth of Zn1−x CdxSe epilayers and ZnSe/Zn 1−xCdxSe superlattices (0≤x≤1) on (100)GaAs was investigated.
Abstract: We have investigated the epitaxial growth of Zn1−x CdxSe epilayers and ZnSe/Zn1−x CdxSe superlattices (0≤x≤1) on (100)GaAs. Although thick epilayers of Zn1−x CdxSe are prone to defect formation with increasing Cd content, the structural and optical characteristics improve remarkably when Zn1−x CdxSe is in the form of thin layers within ZnSe/Zn1−x CdxSe superlattices. High quality superlattices can be grown for x≤0.35. The characterization of these systems using transmission electron microscopy, x‐ray diffraction, reflectivity, and photoluminescence is reported.
TL;DR: The isolation and preliminary characterization of a new G α gene (dgq) in Drosophila is described, yielding two putative proteins that represent a new class of G α subunits because they lack both high amino acid identity with other G α proteins and the pertussis toxin ADP ribosylation site.
TL;DR: The authors evaluate the potential relevance of virtue ethics to the training and practice of professional psychologists, and contrast them with principle ethics, concluding that virtue ethics are an essential component of responsible ethical training.
Abstract: We evaluate the potential relevance of virtue ethics to the training and practice of professional psychologists, and we contrast them with principle ethics. Typically, principles are used to facilitate the selection of socially and historically acceptable answers to the question "What shall I do?" when confronted by ethical dilemmas. Virtue ethics, however, generally focus on the question "Who shall I be?" Strengths and weaknesses of each approach are presented. The impact of each is discussed with respect to informed consent and the therapeutic construct "genuineness." We conclude that virtue ethics are an essential component of responsible ethical training and practice.
TL;DR: Sympatric occurrence of homozygotes for two electro‐morphs controlled by a locus for octanol dehydrogenase, and the absence of heterozygotes, at two localities, indicates two isomorphic species within the taxon Anopheles minimus Theobald in Thailand.
Abstract: Sympatric occurrence of homozygotes for two electromorphs controlled by a locus for octanol dehydrogenase, and the absence of heterozygotes, at two localities, indicates two isomorphic species within the taxon Anopheles minimus Theobald in Thailand. This view is supported by significant, relative deficiencies of heterozygotes at other electromorphic loci. Gene frequency data are reported for seven electromorphic loci in An. minimus sensu lato from eleven localities: one of the newly recognized species predominated in all but one locality and the second was confined to two localities. This species pair of An. minimus s.l. was clearly distinguished from An. aconitus Donitz, An. pampanai Buttiker & Beales and An. varuna Iyengar, three species closely related to An. minimus s.l. in the series Myzomyia of Anopheles subgenus Cellia.
TL;DR: The presence of an arrestin homolog in Drosophila suggests that both the vertebrate and invertebrate phototransduction cascades are regulated in a similar manner.
Abstract: From a group of 436 Drosophila melanogaster cDNA clones, we selected 39 that are expressed exclusively or predominantly in the adult visual system. By sequence analysis, 20 of the clones appear to represent previously unreported distinct cDNAs. The corresponding transcripts are detected in the retina and optic lobes. The genes are scattered throughout the genome, some near mutations known to affect eye function. One of these clones has been identified, by sequence analysis, as the structural gene (Arr) for a Drosophila homolog of human arrestin. Vertebrate arrestin interacts with rhodopsin in phototransduction and has been associated with an autoimmune form of uveitis in primates. The presence of an arrestin homolog in Drosophila suggests that both the vertebrate and invertebrate phototransduction cascades are regulated in a similar manner.
TL;DR: A new technique is presented for designing associative memories to be implemented by Hopfield neural networks that guarantees that each desired memory is stored and is attractive.
Abstract: A new technique is presented for designing associative memories to be implemented by Hopfield neural networks. This technique guarantees that each desired memory is stored and is attractive. The procedure also guarantees that the resulting network can be implemented, a requirement often overlooked by other methods. This synthetic procedure does not require a symmetric interconnection matrix; instead, stability is guaranteed by use of the results presented by A.N. Michel et al. (1989). Two examples are presented that demonstrate the synthesis procedure's storage ability and flexibility. >
TL;DR: In this paper, zone melting has been used to produce texture in extruded YBa2Cu3O6+x wires, where highly aligned microstructures are produced with a b planes oriented along the axis of the wires.
Abstract: Zone melting has been used to produce texture in extruded YBa2Cu3O6+x wires. Highly aligned microstructures are produced with a‐b planes oriented along the axis of the wires. Microstructural observations show that changes in alignment orientation can occur, and can result in the inability to carry a transport current. Pulsed transport Jc measurements on oriented samples indicate a zero field critical current density greater than 4×104 A/cm2.
TL;DR: The moral theory of virtue ethics holds much promise for guiding the behavior of marketers as mentioned in this paper, but it has not received as much emphasis as it has in other areas of the literature.
Abstract: The moral theory of virtue ethics holds much promise for guiding the behavior of marketers. Although the origins of this theory can be traced back to Aristotle, it has not received as much emphasis...
TL;DR: Results show that mechanical inactivation of ligninase is possibly the reason why lignInase accumulation is low or absent in agitated shake-flask cultures, and the detergents Tween 20, Tween 40,Tween 60, Terence 80, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) are able to protect both purified lign inase and extant l
Abstract: The white rot fungus Phanerochaete chrysosporium produces extracellular ligninases as part of its idiophasic ligninolytic system. Agitation has been widely reported to suppress both ligninase production and lignin degradation. Results show that mechanical inactivation of ligninase is possibly the reason why ligninase accumulation is low or absent in agitated shake-flask cultures. Agitation seems to affect the catalytic activity of ligninase and has no apparent effect on either the rate of ligninase production or the physiology of P. chrysosporium. The detergents Tween 20, Tween 40, Tween 60, Tween 80, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) are able to protect both purified ligninase and extant ligninase in culture fluids (free of biomass) against mechanical inactivation due to agitation. Addition of Tween 80 at the end of primary growth to agitated shake flasks containing either pelleted or immobilized mycelial cultures results in production and maintenance of high levels of ligninase activity over several days under conditions of high agitation. Possible mechanisms by which the detergents could protect ligninase are discussed.
TL;DR: In this article, a sharp-edged, flat-plate, delta wing having a sweep angle of 70 deg was used in a study of the dynamic behavior of the leading edge vortices on a delta wing undergoing oscillatory pitching motions.
Abstract: A study of the dynamic behavior of the leading-edge vortices on a delta wing undergoing oscillatory pitching motions is presented, A sharp-edged, flat-plate, delta wing having a sweep angle of 70 deg was used in this investigation. The wing was sinusoidally pitched about its one-half chord position at reduced frequencies ranging from /r = 2ir/c/i/ = 0.05 to 0.30 at root chord Reynolds numbers between 9xl04 and 3.5 x 10s, for angle-ofattack ranges of a = 29 to 39 deg and a = 0 to 45 deg. During these dynamic motions, visualization of the leadingedge vortices was obtained by injecting TiCl4 through ports located near the model apex. The location of vortex breakdown was recorded using high-speed motion-picture photography. The motion-picture records were analyzed to determine the vortex trajectory and breakdown position as a function of angle of attack. When the wing was sinusoidally pitched, hysteresis was observed in the location of the breakdown position. This hysteresis increased with reduced frequency. The velocity of breakdown propagation along the wing and the phase-lag between model motion and breakdown location were also determined. Detailed information was also obtained on the oscillation of breakdown position in both static and dynamic cases.
TL;DR: In this article, a reversed-phase high pressure liquid chromatography was used to quantify carotenoid and chlorophyll degradation resulting from bacterial and microfaunal action during aphotic, hypolimnetic incubations of natural phytoplankton assemblages and detrital material in three lakes.
Abstract: Reversed-phase high pressure liquid chromatography was used to quantify carotenoid and Chl degradation resulting from bacterial and microfaunal action during aphotic, hypolimnetic incubations of natural phytoplankton assemblages and detrital material in three lakes. Decay of carotenoids (to −0.0870 d−1) and chlorophylls (to −0.1226 d−1was potentially rapid but site-specific. Chl a decay spanned a wide range (to −0.1226 d−1) with greatest losses in circumneutral, unstained Peter Lake and least in acidic, stained Tuesday Lake. The usefulness of Chl a as an indicator of algal sedimentation was compromised by its rapid degradation, lack of compensatory production of recognizable derivatives, and an abundance of unknown, chlorophyllous compounds. β-carotene degraded less rapidly and variably (to −0.0167 d−1) and is a useful addition to both sedimentation and paleolimnological studies. Differences among ca rotenoids in decay pose difficulties in reconstructing accurate estimates of former algal community composition, especially dinoflagellates, whose peridinin decays rapidly (−0.0843 d−1). Changes in the relative (within-core) abundance of individual pigments may be combined, however, with changes in Chl a : β-carotene ratios to differentiate between periods of enhanced productivity (or pigment preservation) and changes in the vertical zonation of algal communities.