Showing papers by "University of Auckland published in 1987"
TL;DR: The Euler Method and its Generalizations Analysis of Runge-Kutta Methods General Linear Methods Bibliography.
Abstract: Mathematical and Computational Introduction The Euler Method and its Generalizations Analysis of Runge-Kutta Methods General Linear Methods Bibliography.
1,313 citations
TL;DR: The accuracy of the self-reported data and its effect on the misclassification of relative weight, as measured by Quetelet index, were examined and indicated that self-reports have a high degree of accuracy, however, the participants consistently overestimated their height and underestimated their weight, resulting in an underestimation ofrelative weight.
Abstract: Self-reported and measured height and weight were obtained from a representative sample of 1,598 persons in Auckland, New Zealand during 1982. The accuracy of the self-reported data and its effect on the misclassification of relative weight, as measured by Quetelet index, were examined. The finding that for most participants (75%), self-reported measures were no more than 3.5 cm from their measured height and 2.4 kg from their measured weight indicates that self-reports have a high degree of accuracy. However, the participants consistently overestimated their height and underestimated their weight, resulting in an underestimation of relative weight. This would have little effect on analyses using the self-reported relative weight measures as a continuous covariate, but misclassification would occur when using relative weight as a categorical variable. The sensitivities and specificities associated with categorized self-reported relative risks that have been calculated from relative weight derived from self-reported height and weight.
341 citations
TL;DR: In this paper, the authors investigated local scour around cylindrical bridge piers in uniform, cohesionless sediment and obtained three empirical functions which relate equilibrium scour depth with approach velocity, sediment size and how depth.
Abstract: Local scour around cylindrical bridge piers in uniform, cohesionless sediment was investigated experimentally. Three empirical functions which relate equilibrium scour depth with approach velocity, sediment size and How depth were obtained. The variations of equilibrium scour depth with approach velocity show that the depth of scour decreases at velocities just above the threshold until it reaches a minimum at about twice the threshold velocity. Thereafter, it increases again until a maximum is reached at the transition flat bed condition. At still higher velocity, the equilibrium scour depth decreases due to the formation of antidunes. Both the effects of sediment size and flow depth were found to be independent of the stage of bed particle motion and the approach velocity. Adjustment factors, for the effects of sediment size and flow depth were defined and evaluated.
340 citations
TL;DR: Significantly more hyperactive children had auditory, visual, language, reading, and learning difficulties, and the birth weight ofhyperactive children was significantly lower than that of controls, but there was no increase in asthma, eczema, or other allergies.
Abstract: This study compared 48 hyperactive children with 49 age-and-sex-matched controls. Significantly more hyperactive children had auditory, visual, language, reading, and learning difficulties, and the birth weight of hyperactive children was significantly lower than that of controls (3,058 and 3,410 g, respectively; p < 0.01). In addition, significantly more hyperactive children had frequent coughs and colds, polydypsia, polyuria, and a serious illness or accident in the past year than controls, but there was no increase in asthma, eczema, or other allergies. Serum essential fatty acid (EFA) levels were measured in 44 hyperactive subjects and 45 controls. The levels of docasahexaenoic, dihomogammalinolenic, and arachidonic acids were significantly lower in hyperactive children than controls (docosahexaenoic: 41.6 and 49.5 μg/ml serum respectively, p = 0.045; dihomogammolinolenic: 34.9 and 41.3 μg/ml serum, p = 0.007; arachidonic : 127.1 and 147.0 μg/ml serum, p = 0.027). These findings have possible therapeu...
249 citations
TL;DR: It is concluded that postrecruitment competitive processes play an important role in restricting adult population size in P. amboinensis, at least over the range of densities and on the spatial scale examined.
Abstract: Considerable discussion has arisen over whether population limitation in coral reef fishes is achieved through postrecruitment processes or through factors operating prior to recruitment that lead to insufficient numbers to saturate resources. This paper presents the results of two field experiments designed to document and measure the relative effects of recruitment and subsequent intraspecific competition on populations of the plank- tivorous damselfish Pomacentrus amboinensis, a common species on the Great Barrier Reef. I tested for effects of conspecifics on juvenile mortality, growth, and maturation by manipulating population densities on coral rubble patch reefs. Each experiment examined the potential for competition among juveniles, and between juveniles and adults. The first experiment manipulated the densities of recently settled recruits; the second manipulated 1-yr-old juveniles using a similar experimental design. There were no consistent effects of juvenile density or of adult presence/absence on juvenile survivorship, during either the 0 + yr or the 1 + yr. However, there were substantial effects on growth and maturation. During the 1 st 8 mo of experiment 1, growth was inversely related to initial juvenile density, but was not affected by the presence of adults. A marked negative effect of adults on juvenile growth developed as juveniles approached an age of 1 yr. This effect developed early in experiment 2. Both the mean and the variance in 1 + yr growth were reduced in the presence of adults. Adults primarily affected the growth of the initially largest, behaviorally dominant juveniles. A significantly greater number of 0 + yr and 1 + yr juveniles reached a mature size after 1 yr in treatments without adults present. The numbers maturing were not related to initial density, either with adults present or absent. It is concluded that postrecruitment competitive processes play an important role in restricting adult population size in P. amboinensis, at least over the range of densities and on the spatial scale examined. The mechanism, however, is not one of those traditionally considered in equilibrial models. That is, competition does not appear to modify recruit- ment or mortality patterns directly, but influences numbers maturing through density- dependent effects on maturation time.
244 citations
TL;DR: Models of ethanol input and absorption are crucial to the description and understanding of the effects of ethanol dose on bioavailability and the use of a zero-order model of ethanol elimination has been widespread although the limitations of this model have been known for a long time.
Abstract: The pharmacokinetics of ethanol after typical doses are described by a 1-compartment model with concentration-dependent elimination. The volume of distribution estimated from blood concentrations is about 37 L/70 kg. Protein binding of ethanol has not been reported. Elimination is principally by metabolism in the liver with small amounts excreted in the breath (0.7%), urine (0.3%), and sweat (0.1%). Metabolism occurs, principally by alcohol dehydrogenase, in the liver to acetaldehyde. Models of ethanol input and absorption are crucial to the description and understanding of the effects of ethanol dose on bioavailability. Little attention has been paid to evaluation of potential models. First-pass extraction of ethanol is predicted to be dependent on hepatic blood flow and ethanol absorption rate, with a typical extraction ratio of 0.2. The overall elimination process can be described by a capacity-limited model similar to the Michaelis-Menten model for enzyme kinetics. The maximum rate of elimination of ethanol (elimination capacity or Vmax is 8.5 g/h/70 kg. This would be equivalent to a blood ethanol disappearance rate of 230 mg/L/h if metabolism took place at its maximum rate. The elimination rate is half of the elimination capacity at a peripheral blood ethanol concentration (Km) of about 80 mg/L. Ethanol is readily detectable in expired air. The usual blood:expired air ratio is 2300:1 and breath clearance at rest is 0.16 L/h. The renal clearance of ethanol is 0.06 L/h and sweat clearance is 0.02 L/h. The use of a zero-order model of ethanol elimination has been widespread although the limitations of this model have been known for a long time. Much of the published work on ethanol pharmacokinetics must be regarded with suspicion because of this assumption.
243 citations
TL;DR: The physiology of growth hormone and the insulin- like growth factors are reviewed with particular reference to the dairy industry and the potential is considerable for manipulating the growth hormone insulin-like growth factor axis to enhance lactation.
235 citations
TL;DR: The two ADDH groups resembled each other but the addition of Conduct Disorder brought greater social disability and more adverse family environments.
Abstract: One hundred and five children aged 5-12 with diagnoses of Anxiety, Attention Deficit (ADDH), Conduct, or Oppositional Disorders were compared with each other and with normal subjects. Conduct and Oppositional Disorders resembled each other and seldom occurred in the absence of ADDH so were combined into an ADDH plus Conduct group. Anxiety Disorder children were less predominantly male, less socially or academically disabled, but had more anxious parents. The two ADDH groups resembled each other but the addition of Conduct Disorder brought greater social disability and more adverse family environments.
227 citations
TL;DR: It is suggested that the chondrocyte, its pericellular matrix, and capsule together constitute the “chondron,” a primary functional and metabolic unit of cartilage that acts hydrodynamically to protect the integrity of the chonds and its perICEllular microenvironment during compressive loading.
224 citations
TL;DR: The concentration of extraperikaryal reaction product located rostral to the obex after labelling of the carotid sinus nerve closely matches descriptions of the region of afferent terminations fromcarotid and aortic baroreceptors in the cat.
223 citations
TL;DR: The conclusion is that the type of shallow reef habitat, echinoid- as opposed to algal-dominated, will have an important role in determining the associated reef fish fauna.
TL;DR: The few studies that have compared Attention Deficit with Hyperactivity with Conduct Disorder with or without Anxiety Disorder suggest that ADDH may be a cognitive disorder, possibly of neurodevelopmental origin; Conduct Disorder one of social relationships of psychosocial origin; and Anxiety Disorder less predominantly male, associated with parental anxiety, and less severe than the other two.
Abstract: Studies comparing Attention Deficit. Anxiety, and Conduct Disorders are reviewed. Most studies only compare one diagnostic group with normal subjects, and there are remarkable similarities to observed abnormalities across diagnostic groups. The few studies that have compared Attention Deficit with Hyperactivity (ADDH) with Conduct Disorder with or without Anxiety Disorder suggest that ADDH may be a cognitive disorder, possibly of neurodevelopmental origin; Conduct Disorder one of social relationships of psychosocial origin; and Anxiety Disorder less predominantly male, associated with parental anxiety, and less severe in every way than the other two. Coexistence of Attention Deficit and Conduct Disorders is probably common and increases the degree of disability.
TL;DR: In this paper, a quantum theory of propagation in dispersive nonlinear media is developed, where quantum fluctuations are handled via the coherent-state positive-P representation and a stochastic nonlinear Schr\"odinger equation in the field variables is obtained which predicts wide band squeezing in the region of anomalous dispersion.
Abstract: We develop a quantum theory of propagation in dispersive nonlinear media. Quantum fluctuations are handled via the coherent-state positive-P representation. A stochastic nonlinear Schr\"odinger equation in the field variables is obtained which predicts wide band squeezing in the region of anomalous dispersion. For soliton inputs, fluctuations are reduced over the soliton bandwidth. This leads to quantum solitons which have quadrature fluctuations less than the level of vacuum fluctuations.
TL;DR: The data suggest that reserve status is causal in these differing abundance and size structure estimates for the large, common, reef fish Cheilodactylus spectabilis (Hutton).
Abstract: Total abundance estimates for the large, common, reef fish Cheilodactylus spectabilis (Hutton) were obtained for a marine reserve and adjacent section of coast in north-eastern New Zealand during 1985. Visual strip-transects were used to estimate abundance and size structure in both areas. The accuracy, precision and cost efficiency of five transect sizes (500, 375, 250, 100, 75 m2) were examined over three times per day (dawn, midday and dusk), by simulating transects over mapped C. spectabilis populations. Two transect sizes showed similarly high efficiency. The smaller of the two (20x5 m) was chosen for the survey because of the general advantages attributable to small sampling units. Biases related to strip-transect size are discussed. Preliminary sampling indicated that C. spectabilis was distributed heterogeneously, and that density was habitat-related. An optimal stratified-random design was employed in both locations, to obtain total abundance and size-structure estimates. This reduced the between-habitat source of variability in density. The total number of sampling units used was governed by the time available. The resulting total abundance estimates obtained were 18 338±2 886 (95% confidence limit) for the 5 km marine reserve, compared to 3 987±1 117 for an adjacent, heavily fished 4 km section of coast. When corrected for total area and habitat area sampled, this represented a 2.3-fold difference in abundance. If sampling had been designed to detect an arbitrary 10% difference in abundance within each habitat, an infeasible 440 h of sampling would have been required. Size-frequency distributions of C. spectabilis at the reserve had a larger model size class than distributions from the adjacent area. The data suggest that reserve status is causal in these differing abundance and size structure estimates.
TL;DR: Simultaneous recordings from a swimming zooplankter held close to the fish and from primary afferent neurons provided direct confirmation that swimming movements of crustaceans are a potent natural stimulus of the lateral line system.
Abstract: The suitability of the lateral line system of fish and aquatic amphibia for the detection of planktonic prey was examined in the antarctic fish Pagothenia borcgrevinki (family Nototheniidae). The best responses of primary afferent lateral line neurons to waterborne vibrations were recorded at frequencies within the range of those produced by swimming crustacea. Simultaneous recordings from a swimming zooplankter held close to the fish and from primary afferent neurons provided direct confirmation that swimming movements of crustaceans are a potent natural stimulus of the lateral line system.
TL;DR: The question is raised whether the deficit in verbal IQ is not so much a defect of matching as the essential feature of ADDH from which most of the other commonly reported cognitive symptoms stem.
Abstract: Children aged 5–13 years with DSM-III diagnoses of Attention Deficit (ADDH), Anxiety, (ANX), or Conduct plus ADDH (HC) Disorder and matched normal controls were compared on a set of laboratory measures of impulsivity, arousal, motor performance, activity level, and cognition, and on behavior ratings during testing. While ANX patients did not differ from their controls, ADDH and HC patients did on Verbal IQ, most of the behavior ratings, and on about one-third of the test variables. ANX patients were about 1 year older, and more likely to be female, than ADDH and HC patients. When age, sex, and verbal IQ effects were partialed out, very few differences among the three diagnostic groups remained. The importance of precise control of such variables is emphasized and the impact of the failure to do so in past studies is discussed. The question is raised whether the deficit in verbal IQ is not so much a defect of matching as the essential feature of ADDH from which most of the other commonly reported cognitive symptoms stem.
TL;DR: The major complications of rectal surgery that are wholly or partially avoidable by the use of an anatomically based dissection are haemorrhage from presacral veins, perforation of the rectum, damage to pelvic autonomic nerves and inadequate clearance of a rectal cancer.
Abstract: The major complications of rectal surgery that are wholly or partially avoidable by the use of an anatomically based dissection are haemorrhage from presacral veins, perforation of the rectum, damage to pelvic autonomic nerves and inadequate clearance of a rectal cancer. Important technical points in minimising the incidence of these complications are: (1) posterior dissection in the presacral space; (2) entry to this space by sharp dissection immediately posterior to the superior rectal artery; (3) deliberate incision of the rectosacral fascia; (4) anterior dissection posterior to Denonvilliers fascia in benign disease; (5) removal of the entire mesorectum for low rectal cancer. Other anatomical points not widely appreciated are:
1.
The middle rectal artery does not run in the lateral ligaments of the rectum, but below them, on levator ani. It reaches the rectum by penetrating Denonvilliers' fascia.
2.
The lateral ligaments may contain an accessory middle rectal artery in 25% of cases.
3.
The pelvic autonomic nerves are buried in endopelvic fascia on the pelvic side wall, but come to lie close to the anterior aspect of the rectum at the level of the prostate or upper vagina.
TL;DR: In this article, a quantum theory of propagation in dispersive nonlinear media from the foundations of a correctly quantized field theory is developed, where quantum fluctuations are handled by coherent-state expansions of localized field states.
Abstract: We develop a quantum theory of propagation in dispersive nonlinear media from the foundations of a correctly quantized field theory. Quantum fluctuations are handled by coherent-state expansions of localized field states. A stochastic nonlinear Schrodinger equation in the field variables is obtained for media with an intensity-dependent refractive index. This predicts squeezing for a continuous-wave input, over a wide bandwidth with anomalous dispersion, and over a gradually reducing bandwidth with normal dispersion. The equation is easily modified to include thermal-noise sources as well. For solitons, fluctuations are reduced over the soliton bandwidth. This leads to quantum solitons that have quadrature fluctuations less than the level of vacuum fluctuations. The complementary quadrature has a correspondingly increased fluctuation level.
TL;DR: The 3He/4He ratios of inclusion fluids hosted by gangue and sulphide minerals from Casapalca and Pasto Bueno, Peru, all lie between two and three times the atmospheric value, indicating the presence of a dilute component of mantle helium.
Abstract: Strong differences exist between the helium isotopic compositions of mantle-derived magmas1–8, axial vent hotspring fluids9–14, subduction-related magmas15–20 and many associated hot springs21–24, and the atmospheric and crustal values (Fig. 1). Here we report helium isotope ratios for two late Tertiary fossil hydrothermal systems responsible for precious-metal, base-metal and tungsten mineralization, and compare them to those of circum-Pacific hot-spring emanations. The 3He/4He ratios of inclusion fluids hosted by gangue and sulphide minerals from Casapalca and Pasto Bueno, Peru, all lie between two and three times the atmospheric value, indicating the presence of a dilute component of mantle helium consistent with previously reported stable isotope evidence for the presence of magmatic fluids during mineralization25–27. Although post-trapping modification of the helium isotope composition is possible, we suggest that these apparently low values represent the composition of helium inherited from contributing magmas. As a tracer of magmatic fluids in hydrothermal systems, helium isotopes are decoupled from the factors that govern other stable isotope signatures.
TL;DR: Semi‐synthetic human insulin was delivered via a novel nebulizer to the respiratory tracts of six diabetic children and blood glucose control obtained was at least as good as a control day when they received their usual dose of subcutaneous insulin.
Abstract: Semi-synthetic human insulin was delivered via a novel nebulizer to the respiratory tracts of six diabetic children. Blood glucose control obtained was at least as good as a control day when they received their usual dose of subcutaneous insulin.
TL;DR: In this article, the errors associated with age estimates derived from cores which do not reach the chronological center of the tree (partial cores) are discussed. And the direction of the error is also discussed.
Abstract: Tree-ring counts from increment cores are widely used in ecological studies for determining tree ages. In New Zealand many canopy trees are slow-growing and long-lived, and have extremely narrow rings. Single rings or groups of rings may be absent on some radii. Such narrow and absent rings cause difficulties in ring counting and necessitate careful sample preparation. The errors associated with age estimates derived from cores which do not reach the chronological centre of the tree (partial cores) are discussed. Four partial core lengths and three methods of estimation were used on cross-sections of known age from Agathis australis, Libocedrus bidwillu, Nothofagus solandri, and Prumnopitys taxifolia. It is concluded that mean errors may be less than ± 10% where the core length represents 90% of the geometric radius (half the measured diameter) increase with shorter cores. However, much greater errors may apply to individual estimates, up to ± 78% in one case. Moreover, the direction of the error...
TL;DR: In order to establish the basic connectivity of physiologically identified somatosensory regions of the thalamus and telencephalon in the pigeon, injections of wheatgerm agglutinin-horseradish peroxidase were made under electrophysiological control and the projections were charted following conventional neurohistochemistry.
TL;DR: It was concluded that EFA supplementation, as employed here, produces minimal or no improvements in hyperactive children selected without regard to baseline EFA concentrations.
Abstract: Thirty-one children, selected for marked inattention and overactivity, were studied in a double-blind, placebo-controlled crossover study of essential fatty acid (EFA) supplementation. Subjects received the active treatment and placebo conditions for 4 weeks each and were assessed on a variety of cognitive, motor, and standardized rating scale measures. EFA supplementation (evening primrose oil; Efamol®) resulted in significantly lower levels of palmitoleic acid (a nonessential fatty acid) and higher concentrations of dihomogammalinolenic acid, an EFA previously found to be deficient in some hyperactive children. Supplementation was also associated with significant changes on two performance tasks and with significant improvement to parent ratings on the subscales designated as Attention Problem and Motor Excess of the Revised Behavior Problem Checklist. However, a variety of eight other psychomotor performance tests and two standardized teacher rating scales failed to indicate treatment effects. When the experimentwise probability level was set at.05, only 2 of 42 variables showed treatment effects. Baseline EFA concentrations appeared to be unrelated to treatment response. It was concluded that EFA supplementation, as employed here, produces minimal or no improvements in hyperactive children selected without regard to baseline EFA concentrations.
TL;DR: It is concluded that glucocorticoid drugs probably inhibit the tubular reabsorption of calcium and that this is likely to contribute to the development of osteoporosis in patients receiving this treatment.
Abstract: Fasting urine calcium excretion was measured in 15 asthmatic patients receiving long-term glucocorticoid therapy (steroid group) and in age- and sex-matched asthmatics not receiving these drugs. In the steroid group, the mean urinary calcium/creatinine ratio and the mean calcium excretion per liter of glomerular filtrate (CaE) were both approximately twice the control values (p less than 0.005). When CaE was plotted as a function of serum calcium it more often exceeded the mean normal value in the steroid-treated patients than in the controls (p less than 0.05), suggesting a reduction in tubular calcium reabsorption. Calculation of the tubular maximum for calcium reabsorption confirmed a significant reduction in the glucocorticoid-treated patients (p less than 0.005). It is concluded that glucocorticoid drugs probably inhibit the tubular reabsorption of calcium and that this is likely to contribute to the development of osteoporosis in patients receiving this treatment.
TL;DR: In this paper, the authors considered the active control of flexural vibrations in thin beams and derived the ideal active controller for flexural wave propagation along a waveguide with particular reference to flexural vibration control of thin beams.
TL;DR: A simple model for photoperiodic time measurement in the flesh fly Sarcophaga argyrostoma is described, based on a damped circadian oscillator and the principles of “external coincidence”.
TL;DR: English chaffinches introduced by humans to New Zealand last century have, subsequently colonized the Chatham Islands about 800 km to the east Cultural evolution in songs of the chatham Island population was investigated by comparing a sample of 30 song, types with six equivalent samples from sites in New Zealand.
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TL;DR: The physiological role of Root effect haemoglobins is demonstrably not inevitably linked to the swim bladder but more probably arose from the need to oxygenate the poorly vascularized retina of many fishes.
Abstract: Considering the presently available data it is clear that the Root effect represents an exaggerated alkaline Bohr effect which occurs in the absence of a normal acid Bohr effect and is associated with a loss of oxygen binding capacity at low pH. Undoubtedly at the molecular level the presence of a Ser residue at position F9(94) beta in these haemoglobin is of primary importance. No Root effect haemoglobin has yet been identified which lacks this substitution. On the other hand however many haemoglobins are known which possess this Ser residue and at the same time lack a Root effect. Other factors arising from interactions at other sites in the haemoglobin molecule are obviously sufficient to negate the otherwise stabilizing effect of this critical Ser residue. The loss of cooperativity of Root effect systems as the pH is lowered is readily explained as due to stabilization of the low affinity T state to such a degree that the switch to the high affinity R state is suppressed even in the fully liganded molecule. The observation of Hill coefficients of less than unity requires that within the T state chain heterogeneity exists such that the alpha and beta chain haems demonstrate significantly different affinities for ligand. The physiological role of Root effect haemoglobins is demonstrably not inevitably linked to the swim bladder but more probably arose from the need to oxygenate the poorly vascularized retina of many fishes.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: The results demonstrated that the motor and sensory corticostriate projections are strongly bilateral with an ipsilateral predominance and that they provide collateral projections to the striatum on both sides of the brain.
01 Jan 1987
TL;DR: The idea that organisms are exquisitely designed to fit their environment is a legacy from a static and teleological world view that has a lengthy history in western thought (see Pirlot & Bernier 1973, Bernier et al. 1977, Lewontin 1980, Krimbas 1984).
Abstract: The idea that organisms are exquisitely designed to fit their environment is a legacy from a static and teleological world view that has a lengthy history in western thought (see Pirlot & Bernier 1973, Bernier & Pirlot 1977, Lewontin 1980, Krimbas 1984). It is a tradition that includes Aristotle, the Stoics, St. Thomas Aquinas, and the Natural Theologians. For these writers optimal design was evidence for the existence of various forms of an intelligent creator. This argument for the existence of a creator has become known as the “argument from design.” In its modern guise, the idea of design can be found in the Darwinian concept of adaptation. Darwin rejected God as an explanation of an organism-environment fit but accepted that such a fit existed (see Ospovat 1981).1 Drawing implicitly from Hobbes and Adam Smith, and explicitly from the Natural Theologians and Malthus, he proposed natural selection as a mechanism to explain this fit. In this manner, mechanism was wedded to teleology and Aristotle’s final causes were transformed into today’s “ultimate” or evolutionary causes.2 Mayr (1982, p. 521) asserts that this legitimization of “why questions” was the most important departure in Darwin’s methodology.