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2000

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Articles 12031 - 12060 of 13350

Full-Text Articles in Social and Behavioral Sciences

Clusterin Is A Secreted Mammalian Chaperone, M. R. Wilson, S. B. Easterbrook-Smith Jan 2000

Clusterin Is A Secreted Mammalian Chaperone, M. R. Wilson, S. B. Easterbrook-Smith

Faculty of Science - Papers (Archive)

[Extract] By any criteria, clusterin is an interesting protein. It was first described in 1983 as a secreted glycoprotein in ram rete testis fluid that enhanced aggregation (“clustering”) of a variety of cells in vitro 1. Many homologues in other species were subsequently discovered. Typically, each “discovery” of clusterin in a different species or by a different research group led to it being assigned another name. By the early 1990s clusterin was known under many aliases 2, some of which persist in the literature. However, the inaugural international workshop on clusterin (Cambridge, 1992) agreed to the name clusterin, in deference …


Contribution To The Theory Of Scarpland Development From Observations In Central Queensland, Australia, R. W. Young, R. A. Wray Jan 2000

Contribution To The Theory Of Scarpland Development From Observations In Central Queensland, Australia, R. W. Young, R. A. Wray

Faculty of Science - Papers (Archive)

Theories of scarpland geomorphology developed over the past century have been characterised by divergent conceptual frameworks and have been hindered by language barriers. Here, we review the main theories and assess them with reference to field evidence from central Queensland, Australia.


Thyroid Hormones And Their Effects: A New Perspective, A. J. Hulbert Jan 2000

Thyroid Hormones And Their Effects: A New Perspective, A. J. Hulbert

Faculty of Science - Papers (Archive)

The thyroid hormones are very hydrophobic and those that exhibit biological activity are 3',5',3,5-ltetraiodothyronine (T4), 3',5,3-l-triiodothyronine (T3), 3',5',3-l-triiodothyronine (rT3) and 3,5,-ldiiodothyronine (3,5-T2). At physiological pH, dissociation of the phenolic -OH group of these iodothyronines is an important determinant of their physical chemistry that impacts on their biological effects. When non-ionized these iodothyronines are strongly amphipathic. It is proposed that iodothyronines are normal constituents of biological membranes in vertebrates. In plasma of adult vertebrates, unbound T4 and T3 are regulated in the picomolar range whilst protein-bound T4 and T3 are maintained in the nanomolar range. The function of thyroid-hormone-binding plasma proteins …


Desiccation Tolerance Of Three Moss Species From Continental Antarctica, Sharon A. Robinson, J. Wasley, M. Popp, C. E. Lovelock Jan 2000

Desiccation Tolerance Of Three Moss Species From Continental Antarctica, Sharon A. Robinson, J. Wasley, M. Popp, C. E. Lovelock

Faculty of Science - Papers (Archive)

Tolerance of desiccation was examined in three species of moss, Grimmia antarctici Card., Ceratodon purpureus (Hedw.) Brid. and Bryum pseudotriquetrum (Hedw.) Gaertn., Meyer et Scherb. collected from two sites of contrasting water availability in the Windmill Islands, continental Antarctica. Physiological tolerance to desiccation was measured using chlorophyll fluorescence in plugs of moss during natural drying in the laboratory. Differences in relative water contents, rates of drying and the response of photosynthesis to desiccation were observed among the three species and between sites. Of the three species studied, G. antarctici showed the lowest capacity to sustain photosynthetic processes during desiccation, B. …


Tracing Beach Sand Provenance And Transport Using Foraminifera: Preliminary Examples From Northwest Europe And Southeast Australia, S. K. Haslett, Edward A. Bryant, R. H. Curr Jan 2000

Tracing Beach Sand Provenance And Transport Using Foraminifera: Preliminary Examples From Northwest Europe And Southeast Australia, S. K. Haslett, Edward A. Bryant, R. H. Curr

Faculty of Science - Papers (Archive)

Foraminifera are marine Sarcodine Protozoa that possess tests (shells) that are preservable in the fossil record. These tests may either be constructed using organically cemented detritus (agglutinating or arenaceous forms), or secreted using calcium carbonate (calcareous forms). Their ecology embraces planktonic and benthonic modes, although planktonic forms generally inhabit the open ocean and seldom live in coastal waters in any abundance, while benthonic foraminifera exist on substrates from abyssal plains to high intertidal areas. There are many species of foraminifera that are niche-specific, making them ideal for palaeoenvironmental analysis (Boersma, 1978; Brasier, 1980; Murray, 1991; Culver, 1993).


A Geometric Approach For Three-Phase Load Balancing In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon Jan 2000

A Geometric Approach For Three-Phase Load Balancing In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.


A Novel Method For Loss Minimization In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon, M Buhari Jan 2000

A Novel Method For Loss Minimization In Distribution Networks, Kashem M. Muttaqi, Velappa Ganapathy, G B. Jasmon, M Buhari

Faculty of Engineering and Information Sciences - Papers: Part A

Network reconfiguration for loss minimization is the determination of switching-options that minimizes the power losses for a particular set of loads on a distribution system. In this paper, a novel method is proposed by formulating an algorithm to reconfigure distribution networks for loss minimization. An efficient technique is used to determine the switching combinations, select the status of the switches, and find the best combination of switches for minimum loss. In the first stage of the proposed algorithm, a limited number of switching combinations is generated and the best switching combination is determined. In the second stage, an extensive search …


Diet Composition And Insulin Action In Animal Models, Leonard H. Storlien, J Higgins, T C. Thomas, Marc A. Brown, Hong-Qin Wang, Xu-Feng Huang, Paul Else Jan 2000

Diet Composition And Insulin Action In Animal Models, Leonard H. Storlien, J Higgins, T C. Thomas, Marc A. Brown, Hong-Qin Wang, Xu-Feng Huang, Paul Else

Faculty of Health and Behavioural Sciences - Papers (Archive)

No abstract provided.


Global-Perspective Jitter Improves Vection In Central Vision, Stephen A. Palmisano, Barbara Gillam, Shane Blackburn Jan 2000

Global-Perspective Jitter Improves Vection In Central Vision, Stephen A. Palmisano, Barbara Gillam, Shane Blackburn

Faculty of Health and Behavioural Sciences - Papers (Archive)

Previous vection research has tended to minimise visual - vestibular conflict by using optic-flow patterns which simulate self-motions of constant velocity. Here, experiments are reported on the effect of adding 'global-perspective jitter' to these displays -- simulating forward motion of the observer on a platform oscillating in horizontal and/or vertical dimensions. Unlike non-jittering displays, jittering displays produced a situation of sustained visual - vestibular conflict. Contrary to the prevailing notion that visual - vestibular conflict impairs vection, jittering optic flow was found to produce shorter vection onsets and longer vection durations than non-jittering optic flow for all of jitter magnitudes …


Aureliae: 800 Works From The Otago Polytechnic School Of Art, Su Ballard Jan 2000

Aureliae: 800 Works From The Otago Polytechnic School Of Art, Su Ballard

Faculty of Creative Arts - Papers (Archive)

Mapping a collection

A collection is never fixed, and any identifiable collection is greater than the sum of its parts. As Susan Stewart comments: "while we can 'see' the entire collection, we cannot possibly 'see' each of its elements." (On Longing: Narratives of the Miniat ure, the Gigantic, the Souvenir, the Collection, Baltimore and London: John Hopkins University Press, 1984, p.152). The Otago Polytechnic School of Art collection database lists 836 items, but this is not a complete record. There are other works that have perhaps fallen t hrough crilcks, while some works listed in the database may even dispute …


Slope Instability, Hazard And Risk Associated With A Rainstorm Event - A Case Study, Phillip N. Flentje, Robin N. Chowdhury Jan 2000

Slope Instability, Hazard And Risk Associated With A Rainstorm Event - A Case Study, Phillip N. Flentje, Robin N. Chowdhury

Faculty of Engineering and Information Sciences - Papers: Part A

Over the last few decades there has been an increasing awareness of landslide hazard and risk in many coastal regions of Australia. Urban communities in hilly areas are, from time to time, adversely affected by rainfall-induced landsliding. However, acute awareness of hazard may be absent during periods between significant rainstorm events. In general, the serious consequences of landslides to property and life have been underestimated in Australia. It is now known that at least 80 deaths can be attributed to a number of landslides (Leiba, 1998). Some of these events have focussed the attention of the public, the most important …


Toward A Heuristic Optimum Design Of Rolling Schedules For Tandem Cold Rolling Mills, Dadong Wang, A Kiet Tieu, Friso Deboer, B Ma, W. Y. Daniel Yuen Jan 2000

Toward A Heuristic Optimum Design Of Rolling Schedules For Tandem Cold Rolling Mills, Dadong Wang, A Kiet Tieu, Friso Deboer, B Ma, W. Y. Daniel Yuen

Faculty of Engineering and Information Sciences - Papers: Part A

Scheduling for tandem cold mills refers to the determination of inter-stand gauges, tensions and speeds of a specified product. Optimal schedules should result in maximized throughput and minimized operating cost. This paper presents a genetic algorithm based optimization procedure for the scheduling of tandem cold rolling mills. The optimization procedure initiates searching from a logical staring point - an empirical rolling schedule - and ends with an optimum cost. Cost functions are constructed to heuristically direct the genetic algorithm's searching, based on the consideration of power distribution, tension, strip flatness and rolling constraints. Numerical experiments have shown that the proposed …


The Kth-Order Nonhomomorphicity Of S-Boxes, Yuliang Zheng, Xian-Mo Zhang Jan 2000

The Kth-Order Nonhomomorphicity Of S-Boxes, Yuliang Zheng, Xian-Mo Zhang

Faculty of Engineering and Information Sciences - Papers: Part A

Nonhomomorphicity is a new nonlinearity criterion of a mapping or S-box used in a private key encryption algorithm. An important advantage of nonhomomorphicity over other nonlinearity criteria is that the value of nonhomomorphicity is easy to estimate by the use of a fast statistical method. Due to the Law of Large Numbers, such a statistical method is highly reliable. Major contributions of this paper are (1) to explicitly express the nonhomomorphicity by other nonlinear characteristics, (2) to identify tight upper and lower bounds on nonhomomorphicity, and (3) to find the mean of nonhomomorphicity over all the S-boxes with the same …


Influence Of In-Plane Displacement And Double-Aperture Orientation On Slope Fringe Formation In Double-Shearing-Aperture Speckle Interferometry, K F. Wang, A Kiet Tieu, Enbang Li Jan 2000

Influence Of In-Plane Displacement And Double-Aperture Orientation On Slope Fringe Formation In Double-Shearing-Aperture Speckle Interferometry, K F. Wang, A Kiet Tieu, Enbang Li

Faculty of Engineering and Information Sciences - Papers: Part A

The influence of the in-plane displacement and double-aperture orientation on the slope fringe formation in double-shearing-aperture speckle interferometry is discussed in detail. The research results show that the two in-plane displacement components, one parallel to and the other perpendicular to the shearing direction, have an influence on the slope fringe formation and that the double-aperture orientation also has an important influence on the slope fringe formation. A theoretical analysis and experimental results are presented. The experimental results are in good agreement with the theoretical analysis.


Fuelling Quasars With Hot Gas, Paul E J Nulsen, A C. Fabian Jan 2000

Fuelling Quasars With Hot Gas, Paul E J Nulsen, A C. Fabian

Faculty of Engineering and Information Sciences - Papers: Part A

We consider a model for quasar formation in which massive black holes are formed and fuelled largely by the accretion of hot gas during the process of galaxy formation. In standard hierarchical collapse models, objects about the size of normal galaxies and larger form a dense hot atmosphere when they collapse. We show that if such an atmosphere forms a nearly ‘maximal’ cooling flow, then a central black hole can accrete at close to its Eddington limit. This leads to exponential growth of a seed black hole, resulting in a quasar in some cases. In this model, the first quasars …


A Physical Model For The Hard X-Ray Background, R J. Wilman, A C. Fabian, Paul E J Nulsen Jan 2000

A Physical Model For The Hard X-Ray Background, R J. Wilman, A C. Fabian, Paul E J Nulsen

Faculty of Engineering and Information Sciences - Papers: Part A

We combine a semi-analytic galaxy formation model with a prescription for the obscured growth of massive black holes, to reproduce the hard X-ray background (XRB), the local 2–10 keV active galactic nuclei (AGN) luminosity function and the source counts, including recent Chandra results. The model also complies with constraints on the AGN contribution to the far-infrared and submillimetre backgrounds.

The comoving density of luminous AGN [L(2-10keV) > 1044 erg s-1, in the unabsorbed rest-frame] in the model declines sharply since z=2, mimicking the observed evolution of the quasar population. The abundance of lower luminosity AGN simultaneously increases, and …


Convergence Of Eigenvalues In State-Discretization Of Linear Stochastic Systems, Jose A. De Dona, Graham C. Goodwin, Richard H. Middleton, Iain Raeburn Jan 2000

Convergence Of Eigenvalues In State-Discretization Of Linear Stochastic Systems, Jose A. De Dona, Graham C. Goodwin, Richard H. Middleton, Iain Raeburn

Faculty of Engineering and Information Sciences - Papers: Part A

The transition operator that describes the time evolution of the state probability distribution for continuous-state linear systems is given by an integral operator. A state-discretization approach is proposed, which consists of a finite rank approximation of this integral operator. As a result of the state-discretization procedure, a Markov chain is obtained, in which case the transition operator is represented by a transition matrix. Spectral properties of the integral operator for the continuous-state case are presented. The relationships between the integral operator and the finite rank approximation are explored. In particular, the limiting properties of the eigenvalues of the transition matrices …


The Berry-Esseen Bound For Studentized Statistics, Qiying Wang, Bing-Yi Jing, Lincheng Zhao Jan 2000

The Berry-Esseen Bound For Studentized Statistics, Qiying Wang, Bing-Yi Jing, Lincheng Zhao

Faculty of Engineering and Information Sciences - Papers: Part A

We derive Berry-Esseen bounds for a class of Studentized statistics. The results are applied to Studentized U-statistics, Studentized L-statistics and Studentized functions of the sample mean to give the Berry-Esseen bounds under conditions weaker than those obtained by alternative methods.


Expedited Broda-Damas Bracket Abstraction, Martin W. Bunder Jan 2000

Expedited Broda-Damas Bracket Abstraction, Martin W. Bunder

Faculty of Engineering and Information Sciences - Papers: Part A

A bracket abstraction algorithm is a means of translating λ-terms into combinators. Broda and Damas, in [1], introduce a new, rather natural set of combinators and a new form of bracket abstraction which introduces at most one combinator for each λ-abstraction. This leads to particularly compact combinatory terms. A disadvantage of their abstraction process is that it includes the whole Schonfinkel [4] algorithm plus two mappings which convert the Schonfinkel abstract into the new abstract. This paper shows how the new abstraction can be done more directly, in fact, using only 2n - 1 algorithm steps if there are n …


Specific Yield For A Two-Dimensional Flow, Peter Tritscher, W Wayne Read, Philip Broadbridge Jan 2000

Specific Yield For A Two-Dimensional Flow, Peter Tritscher, W Wayne Read, Philip Broadbridge

Faculty of Engineering and Information Sciences - Papers: Part A

We investigate the systematic secular spatial variation of specific yield. As a vehicle for this analysis we consider a canonical unconfined aquifer consisting of a porous zone whose cross section is a simple long rectangle. The hydraulic conductivity in the unsaturated zone is modeled by the quasi-linear approximation. We find that locally the specific yield may be strongly influenced by the water table depth and mildly dependent on the recharge rate if that rate is high. For the simple geometry considered, a lateral component of flow has been found to have an insignificant effect on the local specific yield and …


Comparing Species Of Bees For Controlled Pollination Of Helianthus Petiolaris In Field Cages, R. L. Wilson, C. A. Abel, M. E. Brothers Jan 2000

Comparing Species Of Bees For Controlled Pollination Of Helianthus Petiolaris In Field Cages, R. L. Wilson, C. A. Abel, M. E. Brothers

Journal of the Iowa Academy of Science: JIAS

Honey bees, Apis mellifera, have been used for several years to pollinate caged plant species maintained at the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS), Ames, Iowa. Because maintaining large numbers of honey bees is expensive and time consuming, we began looking in 1995 for other pollinator species that can be easily managed and less expensive to maintain than A. mellifera. One species we tested was the hornfaced bee, Osmia cornifrons, a solitary bee imported from Japan in the late 1970s. We also tested a mixture of native bumblebees, Bombus bimaculatus and B. impatiens, which are native to the …


The Status Of The Blacknose Shiner (Notropis Heterolepis) Tn Iowa: A Preliminary Survey, Neil P. Bernstein, Michael Getting, Timothy Kamp, Stevenson Christain, Ryan Smith, Joseph Steele, Steven Steele Jan 2000

The Status Of The Blacknose Shiner (Notropis Heterolepis) Tn Iowa: A Preliminary Survey, Neil P. Bernstein, Michael Getting, Timothy Kamp, Stevenson Christain, Ryan Smith, Joseph Steele, Steven Steele

Journal of the Iowa Academy of Science: JIAS

During the last 45 years, the blacknose shiner (Notropis heterolepis) has been restricted to a three county area in northwestern Iowa. We surveyed locations where this siltation-intolerant species had been captured to update the status of the fish in the state. Streams were blocked with nets on both the upstream and downstream ends of sample areas, and fish were collected with a backpack electrofisher and seines. Lakes where the blacknose shiner had been found were also sampled. No blacknose shiners were found and several possible explanations are offered for their absence from historical sites.


Editorial Board & Iowa Academy Of Science Officers And Directors Jan 2000

Editorial Board & Iowa Academy Of Science Officers And Directors

Journal of the Iowa Academy of Science: JIAS

No abstract provided.


Back Cover Jan 2000

Back Cover

Journal of the Iowa Academy of Science: JIAS

No abstract provided.


Distribution And Abundance Of Three Freshwater Mussel Species (B1valv1a: U Ntontdae) Correlated With Physical Habitat Characteristics In An Iowa Reservoir, J. R. Straka, J. A. Downing Jan 2000

Distribution And Abundance Of Three Freshwater Mussel Species (B1valv1a: U Ntontdae) Correlated With Physical Habitat Characteristics In An Iowa Reservoir, J. R. Straka, J. A. Downing

Journal of the Iowa Academy of Science: JIAS

A rapid drawdown (weeks) of a reservoir allowed us to determine the combined influence of water depth, maximum effective fetch, bottom slope, and substrate characteristics on abundance of three species of freshwater mussels. The three principal mussel species were significantly (PPyganodon grandis(Say) was most abundant on deeper shelves (ca. 3 m depth, slope 1 km), and sediment organic matter content was moderate (Lampsilis siliquoidea(Barnes), however, was most abundant in shallow water (Potamilus alatus(Say) had a more cosmopolitan depth distribution, but was found only on bottoms with low slope (Pyganodon grandiswas found to be negatively affected by increasing substrate organic matter …


Population Size Estimates For The Endangered Iowa Pleistocene Snail, Discus Macclintocki Baker, Tama K. Anderson Jan 2000

Population Size Estimates For The Endangered Iowa Pleistocene Snail, Discus Macclintocki Baker, Tama K. Anderson

Journal of the Iowa Academy of Science: JIAS

Discus macclintocki Baker, the Iowa Pleistocene snail, is a federally endangered species found only on algific talus slopes in northeastern Iowa and northwestern Illinois. Population size estimates for fourteen D. macclintocki populations in Iowa and Illinois ranged from 182 to 22,125 individuals. Estimates from the program CAPTURE as well as Bayesian estimation procedures gave similar results, although the Bayesian method allowed estimation of populations that could not be estimated with CAPTURE due to small sample sizes. A comparison of two methods of sampling, visual counts of quadrats and cover boards, showed that using cover boards resulted in much higher probabilities …


Editorial Board & Iowa Academy Of Science Officers And Directors Jan 2000

Editorial Board & Iowa Academy Of Science Officers And Directors

Journal of the Iowa Academy of Science: JIAS

No abstract provided.


Table Of Contents Jan 2000

Table Of Contents

Journal of the Iowa Academy of Science: JIAS

No abstract provided.


Morphological Abnormalities In Illinois Cricket Frogs, Acris Crepitans, 1968-71, Robert H. Gray Jan 2000

Morphological Abnormalities In Illinois Cricket Frogs, Acris Crepitans, 1968-71, Robert H. Gray

Journal of the Iowa Academy of Science: JIAS

Reports of malformed amphibians have been increasing, including external deformities such as missing or extra arms and legs, missing eyes and mandibles, and internal abnormalities involving the bladder, digestive system, and testes. Natural phenomena such as limb amputations during predation attempts by other animals, parasitism, xenobiotic chemicals (herbicides, insecticides, fertilizers and others), and UV-B or other radiation (either directly or indirectly by triggering production of toxicants from nontoxic chemicals) have all been linked to amphibian abnormalities. From 1968-71, I studied the natural history, effective breeding size, and seasonal, annual, and geographic variation in color morph frequencies of cricket frogs (Acris …


Field Investigations Of Malformed Frogs In Minnesota 1993-97, Judy C. Helgen, Mark C. Gernes, Susan M. Kersten, Joel W. Chirhart, Jeff T. Canfield, Dorothy Bowers, Jon Haferman, Robert G. Mckinnell, David M. Hoppe Jan 2000

Field Investigations Of Malformed Frogs In Minnesota 1993-97, Judy C. Helgen, Mark C. Gernes, Susan M. Kersten, Joel W. Chirhart, Jeff T. Canfield, Dorothy Bowers, Jon Haferman, Robert G. Mckinnell, David M. Hoppe

Journal of the Iowa Academy of Science: JIAS

Reports of malformed frogs were made to the Minnesota Pollution Control Agency (MPCA) from different parts of Minnesota in 1993, 1995, 1996, and 1997 and one, nine, 190, and 172 reports were received, respectively. MPCA field crews and Drs. Hoppe and McKinnell documented malformed frog locations starting in 1993. By 1997, MPCA field crews documented malformed frogs at 62 locations in Minnesota, in 29 of 87 counties. Most malformations were in young metamorphs of Rana pipiens but they were observed also in R. clamitans, R. septentrionalis, R. sylvatica, Bufo americanus, and Hyla spp. Frequencies of malformations varied by time of …