Showing papers by "University of Western Australia published in 2000"
University of Otago1, University of East Anglia2, Plymouth Marine Laboratory3, Wellington Management Company4, University of Tasmania5, University of Plymouth6, Woods Hole Oceanographic Institution7, University of Maine8, McGill University9, Bowling Green State University10, Hobart Corporation11, University of British Columbia12, University of Western Australia13
TL;DR: It is demonstrated that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.
Abstract: Changes in iron supply to oceanic plankton are thought to have a significant effect on concentrations of atmospheric carbon dioxide by altering rates of carbon sequestration, a theory known as the 'iron hypothesis' For this reason, it is important to understand the response of pelagic biota to increased iron supply Here we report the results of a mesoscale iron fertilization experiment in the polar Southern Ocean, where the potential to sequester iron-elevated algal carbon is probably greatest Increased iron supply led to elevated phytoplankton biomass and rates of photosynthesis in surface waters, causing a large drawdown of carbon dioxide and macronutrients, and elevated dimethyl sulphide levels after 13 days This drawdown was mostly due to the proliferation of diatom stocks But downward export of biogenic carbon was not increased Moreover, satellite observations of this massive bloom 30 days later, suggest that a sufficient proportion of the added iron was retained in surface waters Our findings demonstrate that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction
1,412 citations
TL;DR: Consideration of the primal and dual problems together leads to important new insights into the characteristics of the LASSO estimator and to an improved method for estimating its covariance matrix.
Abstract: Proposed by Tibshirani, the least absolute shrinkage and selection operator (LASSO) estimates a vector of regression coefficients by minimizing the residual sum of squares subject to a constraint on the l 1-norm of the coefficient vector. The LASSO estimator typically has one or more zero elements and thus shares characteristics of both shrinkage estimation and variable selection. In this article we treat the LASSO as a convex programming problem and derive its dual. Consideration of the primal and dual problems together leads to important new insights into the characteristics of the LASSO estimator and to an improved method for estimating its covariance matrix. Using these results we also develop an efficient algorithm for computing LASSO estimates which is usable even in cases where the number of regressors exceeds the number of observations. An S-Plus library based on this algorithm is available from StatLib.
763 citations
TL;DR: In this paper, the authors used an ion microprobe (SHRIMP II) to analyze trondhjemitic magmatism at 2.90-2.95 Ga in the Kongling area of the Yangtze craton, south China, about 150 km south of the Permian-Triassic Qinling-Dabie-Sulu orogenic belt.
Abstract: Ion microprobe (SHRIMP II) U-Pb zircon analyses reveal trondhjemitic magmatism at 2.90–2.95 Ga in the Kongling area of the Yangtze craton, south China, about 150 km south of the Permian-Triassic Qinling-Dabie-Sulu orogenic belt. Detrital zircons from nearby Archean metapelites are 2.87–3.28 Ga, and the rocks have Sm-Nd depleted mantle model ages of 3.07–3.21 Ga. The new data reveal, for the first time, >3.2 Ga sialic crust in the Yangtze craton, part of which predates that of the adjacent southern North China craton. Both trondhjemites and metapelites contain ca. 2.75 Ga high-grade metamorphic zircons, and ca. 1.9 Ga zircons, related to intrusion of the Quanqitang K-feldspar granite into the Archean basement. Many zircons also underwent Pb loss ca. 1.0 Ga during the Jinning orogeny, when the Cathysian block accreted to the Yangtze craton. The new data support correlation of part of the Korean Peninsula with the Yangtze craton along the eastern extension of the Qinling-Dabie-Sulu orogenic belt.
717 citations
TL;DR: In this article, a general theoretical formulation of the bias problem is proposed, and an expression for the interface energy is derived, with particular emphasis on the roles of interface structure and temperature.
Abstract: Modern applications for thin film magnets involve unique requirements for the control and design of specific magnetic properties. The exchange bias effect in ferromagnet/antiferromagnet bilayers appears to be a useful feature for controlling one of the most important characteristics of a ferromagnet: coercivity. Prospects for control and enhancement of desirable effects depend upon a clear understanding of mechanisms governing exchange bias. The processes underlying the existence and properties of exchange bias are reviewed, with particular emphasis on the roles of interface structure and temperature. Results from numerical simulations are used to illustrate how exchange bias is modified by geometric structures at the interface and randomly placed defects. A general theoretical formulation of the bias problem is proposed, and an expression for the interface energy is derived. A key result is the existence of higher-order coupling terms when more than one sublattice of the antiferromagnet is present at the interface. Results from calculations of finite temperature effects on bias and coercivity are described, and the concept of viscosity in the antiferromagnet is discussed. A brief discussion is also included of how a dynamic linear response, such as ferromagnetic resonance or light scattering, can be used to determine relevant anisotropy and exchange parameters.
689 citations
TL;DR: EPA and DHA had differential effects on lipids, fatty acids, and glucose metabolism in overweight men with mild hyperlipidemia.
644 citations
TL;DR: In this article, the authors develop methods for analysing the interaction or dependence between points in a spatial point pattern, when the pattern is spatially inhomogeneous, using an analogue of the K-function.
Abstract: We develop methods for analysing the ‘interaction’ or dependence between points in a spatial point pattern, when the pattern is spatially inhomogeneous. Completely non-parametric study of interactions is possible using an analogue of the K-function. Alternatively one may assume a semi-parametric model in which a (parametrically specified) homogeneous Markov point process is subjected to (non-parametric) inhomogeneous independent thinning. The effectiveness of these approaches is tested on datasets representing the positions of trees in forests.
601 citations
TL;DR: The survival benefits seen in patients treated with adjuvant chemotherapy suggest that data from previous trials of adjUvant chemotherapy should be reassessed and the predictive value of MSI status confirmed.
541 citations
TL;DR: This paper attempts to show that previously proposed hyper-viscoelastic constitutive constitutive model of brain tissue can be applied to simulating surgical procedures, and an in vivo indentation experiment is described.
532 citations
TL;DR: Changes in coronary care and secondary prevention were strongly linked with declining coronary endpoints.
499 citations
TL;DR: Finding that a large percentage of children can be equally classified as SRD or SLI has repercussions for the criteria used to define an SRD, for conceptualising subgroups of learning disability, and for estimates of the incidence of SRD.
Abstract: The reading and oral language scores of 110 children with a specific reading disability (SRD) and 102 children with a specific language impairment (SLI) indicated that approximately 53% of children with an SRD and children with an SLI could be equally classified as having an SRD or an SLI, 55% of children with an SRD have impaired oral language, and 51% of children with an SLI have a reading disability Finding that a large percentage of children can be equally classified as SRD or SLI has repercussions for the criteria used to define an SRD, for conceptualising subgroups of learning disability, and for estimates of the incidence of SRD Further, it highlights the need for future studies to assess both the reading and oral language abilities of SRD and SLI participants to determine how specifically impaired and homogeneous samples really are
483 citations
TL;DR: The reasons for considering giardiasis as a re-emerging infectious disease are presented, with emphasis on Giardia infections in child care centres, livestock and pets, and the role of zoonotic transmission.
TL;DR: The emerging pattern of risk factors and antecedents of schizophrenia suggests multiple, mainly quantitative deviations from the average developmental trajectory, primarily in the areas of early neurodevelopment, cognitive ability and social behaviour, compatible with the notion of non-specific background factors facilitating the operation of genetically determined causal pathways.
Abstract: Evidence from nearly a century of epidemiological research indicates that schizophrenia occurs in all populations with a prevalence in the range of 1.4 to 4.6 per 1000 and incidence rates in the range of 0.16-0.42 per 1000 population. Multi-centre studies conducted by the World Health Organization have highlighted important differences between 'Western' and 'Third World' populations as regards the course and outcome of the disorder, with a significantly better prognosis in the developing countries. The factors underlying the better outcome of schizophrenia in developing countries remain essentially unknown but are likely to involve interactions between genetic variation and specific aspects of the environment. These features place schizophrenia, along with diabetes, cancer and hypertension, into the group of genetically complex diseases which are characterised by polygenic transmission, locus heterogeneity and environmental contribution to causation. The emerging pattern of risk factors and antecedents of schizophrenia suggests multiple, mainly quantitative deviations from the average developmental trajectory, primarily in the areas of early neurodevelopment, cognitive ability and social behaviour. These deviations are compatible with the notion of non-specific background factors facilitating the operation of genetically determined causal pathways. Research likely to result in new insights should focus on the population distribution and behavioural effects of potential risk factors and markers suggested by biological and genetic research.
TL;DR: There is a need for a broad programmatic approach, involving various sectors of the community, to tackle the multiple dimensions of clinical disorder, personal functioning and socioeconomic environment that influence the course and outcome of psychosis and ultimately determine the effectiveness of service-based intervention.
Abstract: Objective: This paper reports on a study designed within the framework of the National Survey of Mental Health and Wellbeing to: estimate the prevalence of psychoses in urban areas of Australia; identify profiles of symptomatology, impairments and disabilities; collect information on services received and needed; and explore quality of life issues in a broadly representative sample of people with psychotic illnesses.Method: The study was conducted over four areas in the Australian Capital Territory, Queensland, Victoria and Western Australia, as a two-phase survey: (i) a census and screening for psychosis of all individuals who made contacts with mental health services during a period of 1 month in 1997; and (ii) interviews with a stratified random sample (n = 980) of the screen-positive individuals (n = 3800) using a standardised instrument.Results: The point prevalence (1 month) of psychotic disorders in the urban population aged 18–64 is in the range of 4–7 per 1000 with a weighted mean of 4.7 per 1000...
TL;DR: The interpretation of U-Pb and Sm-Nd isotopic data has led to a new understanding of the subdivision and evolution of the Amazon Craton during Precambrian time, with major improvements and changes made to the previous Rb-Sr based model.
TL;DR: In this paper, a 3D mixed-layer model for surface dynamics with a semi-implicit method similar to the momentum solution in the TRIM code with the addition of quadratic Euler-Lagrange dis- cretization, scalar transport using a conservative flux-limited approach, and elimination of vertical diffusion terms in the governing equations is presented.
Abstract: Basin-scale internal waves provide the driving forces for vertical and horizontal fluxes in a stratified lake below the wind-mixed layer. Thus, correct modeling of lake mixing and transport requires accurate modeling of basin- scale internal waves: examining this capability with a hydrostatic, z-coordinate three-dimensional (3D) numerical model at coarse grid resolutions is the focus of this paper. It is demonstrated that capturing the correct thermocline forcing with a 3D mixed-layer model for surface dynamics results in a good representation of low-frequency internal wave dynamics. The 3D estuary and lake computer model ELCOM is applied to modeling Lake Kinneret, Israel, and is compared with field data under summer stratification conditions to identify and illustrate the spatial structure of the lowest-mode basin-scale Kelvin and Poincarewaves that provide the largest two peaks in the internal wave energy spectra. The model solves the unsteady Reynolds-averaged Navier-Stokes equations using a semi-implicit method similar to the momentum solution in the TRIM code with the addition of quadratic Euler-Lagrange dis- cretization, scalar (e.g., temperature) transport using a conservative flux-limited approach, and elimination of vertical diffusion terms in the governing equations. A detailed description is provided of turbulence closure for the vertical Reynolds stress terms and vertical turbulent transport using a 3D mixed-layer model parameterized on wind and shear energy fluxes instead of the convential eddy viscosity/diffusivity assumption. This approach gives a good representation of the depth of the mixed-layer at coarse vertical grid resolutions that allows the internal waves to be energized correctly at the basin scale. Wind stresses, surface heating, and density currents form the driving energy fluxes of a stratified lake. The basin-scale energy flux from the wind is of particular interest because of its dominant role in setting the thermocline in motion, which, in the absence of inflows and outflows, is the primary energy store for transport and mixing below the wind-mixed layer. Thus, modeling the basin-scale internal wave behavior is an a priori requirement to modeling and quantifying the flux paths of nutrients in a stratified lake (Imberger 1994). This paper takes a first step in this direction by analyzing our ability to model basin-scale internal waves that are seen in Lake Kinneret, Israel. Energy flux path in a stratified lake —Energy flux through a stratified lake has a fundamental dependence on forced and free baroclinic motions. The wind imparts both momentum and turbulent kinetic energy (TKE) to the water in the sur- face layer. The TKE distributes momentum vertically in the
TL;DR: In this paper, a 45 km section near Yecheng in the western Kunlun Mountains of the northern Tibetan Plateau was investigated and the change from deposition on distal alluvial plains to proximal fans occurred during the Gilbert reversed chron (45-35 Ma) followed by an increase in sedimentation rate.
Abstract: Neogene redbeds passing upward into upward-coarsening conglomerate and debris-flow deposits at the foot of the Kunlun Mountains record the change in paleoslope related to uplift of the surface of the northern Tibetan Plateau Detailed magnetostratigraphy of a 45 km section near Yecheng in the western Kunlun Mountains shows that the change from deposition on distal alluvial plains to proximal alluvial fans occurred during the Gilbert reversed chron (45–35 Ma) The change in depositional facies was accompanied by an increase in sedimentation rate from an average ∼015 mm/yr between the earliest Oligocene and the earliest Pliocene to 14 mm/yr in the Gauss normal chron (36–26 Ma) We interpret the change in depositional facies and increase in sedimentation rate as indicating that the main uplift of the northwestern Tibetan Plateau began ca 45 Ma
TL;DR: Improvements in endothelium-independent mechanisms appear to be predominant and may contribute to the selective blood pressure–lowering effect observed with DHA compared with EPA in humans.
Abstract: Background—Recent evidence supports differential effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the 2 major ω3 fatty acids of marine origin, on blood pressure in humans and vascular reactivity in adult spontaneously hypertensive rats. We investigated possible differences in the effects of purified EPA or DHA on forearm vascular reactivity in overweight hyperlipidemic men that might contribute to the blood pressure–lowering effects of fish oils. Methods and Results—With a double-blind, placebo-controlled trial of parallel design, 59 overweight, mildly hyperlipidemic men were randomized to receive 4 g/d purified EPA, DHA, or olive oil (placebo) capsules while continuing their usual diets for 6 weeks. Forearm blood flow (FBF) was measured with venous occlusion, strain-gauge plethysmography during the sequential intra-arterial administration of acetylcholine (7.5, 15, and 30 μg/min), sodium nitroprusside (1.5, 3, and 10 μg/min), norepinephrine (10, 20, and 40 ng/min), a single-dose inf...
TL;DR: This data indicates that high intake of dietary anti‐oxidants may protect against cardiovascular disease through the role that oxidative events in vivo may play a role in the pathogenesis of atherosclerosis.
Abstract: 1. There has been considerable recent interest in the possibility that increased intake of dietary anti-oxidants may protect against cardiovascular disease. This is partly due to the knowledge that oxidative events in vivo may play a role in the pathogenesis of atherosclerosis. 2. While dietary anti-oxidants, such as vitamins E and C, have received considerable attention in this regard, relatively little is known about a similar anti-oxidant role for plant-derived polyphenolic compounds, such as the flavonoids and phenolic acids. A review of the distribution, bioavailability and biological activity of these compounds suggests that they may have a physiological role as anti-oxidants. 3. Human trials on the anti-oxidant effects of beverages rich in polyphenolics, such as red wine, fruit juice or tea, have been limited and results are, at present, inconclusive. This is due, in part, to poor methodologies available to measure oxidative damage in vivo. 4. There is a sound rationale for considering polyphenolics as important contributors to the dietary anti-oxidant intake derived from fruits and vegetables. However, continuing research is needed using appropriate biomarkers of oxidant damage in vivo before these compounds can be conclusively considered as dietary anti-oxidants with nutritional benefit.
TL;DR: To improve confidence in isotopic techniques for estimating N2 fixation differences in the form and function of plant roots are highlighted as critical areas for future research, as is a greater understanding of the total N contained in legume roots.
TL;DR: The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes and reduce the production in vitro of tumour necrosis factor-α, IL-1β and IL-10 by lipopolysaccharide-activated human peripheral blood monocytes.
Abstract: Objective and Design: To evaluate potential anti-inflammatory properties of tea tree oil, the essential oil steam distilled from the Australian native plant, Melaleuca alternifolia.¶Material and Methods: The ability of tea tree oil to reduce the production in vitro of tumour necrosis factor-α (TNFα), interleukin (IL)-1β, IL-8, IL-10 and prostaglandin E2 (PGE2) by lipopolysaccharide (LPS)-activated human peripheral blood monocytes was examined.¶Results: Tea tree oil emulsified by sonication in a glass tube into culture medium containing 10% fetal calf serum (FCS) was toxic for monocytes at a concentration of 0.016% v/v. However, the water soluble components of tea tree oil at concentrations equivalent to 0.125% significantly suppressed LPS-induced production of TNFα, IL-1β and IL-10 (by approximately 50%) and PGE2 (by approximately 30%) after 40 h. Gas chromatography/ mass spectrometry identified terpinen-4-ol (42%), α-terpineol (3%) and 1,8-cineole (2%, respectively, of tea tree oil) as the water soluble components of tea tree oil. When these components were examined individually, only terpinen-4-ol suppressed the production after 40 h of TNFα, IL-1β, IL-8, IL-10 and PGE2 by LPS-activated monocytes.
Conclusion: The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes.
TL;DR: The discovery of pyritic filaments, the probable fossil remains of thread-like microorganisms, in a 3,235-million-year-old deep-sea volcanogenic massive sulphide deposit from the Pilbara Craton of Australia is reported, representing the first fossil evidence for microbial life in a Precambrian submarine thermal spring system.
Abstract: The record of Archaean microfossils is sparse. Of the few bona fide fossil assemblages, most are from shallow-water settings, and they are typically associated with laminated, stromatolitic sedimentary rocks. Microfossils from deep-sea hydrothermal systems have not been reported in Precambrian rocks (> 544 million years old), although thermophilic microbes are ubiquitous in modern sea-floor hydrothermal settings, and apparently have the most ancient lineages. Here, I report the discovery of pyritic filaments, the probable fossil remains of thread-like microorganisms, in a 3,235-million-year-old deep-sea volcanogenic massive sulphide deposit from the Pilbara Craton of Australia. From their mode of occurrence, the micro-organisms were probably thermophilic chemotropic prokaryotes, which inhabited sub-sea-floor hydrothermal environments. They represent the first fossil evidence for microbial life in a Precambrian submarine thermal spring system, and extend the known range of submarine hydrothermal biota by more than 2,700 million years. Such environments may have hosted the first living systems on Earth, consistent with proposals for a thermophilic origin of life.
TL;DR: Results show that even temporary overexpression of VEGF in retinal pigment epithelial cells is sufficient to induce choroidal neovascularization in the rat eye.
Abstract: Vascular endothelial growth factor (VEGF) has been strongly implicated in the development of choroidal neovascularization found in age-related macular degeneration. Normally expressed in low levels, this study investigates whether the overexpression of VEGF in the retinal pigment epithelium is sufficient to cause choroidal neovascularization in the rat retina. A recombinant adenovirus vector expressing the rat VEGF 164 cDNA (AdCMV.VEGF) was constructed and injected into the subretinal space. The development of neovascularization was followed by fluorescein angiography, which indicates microvascular hyperpermeability of existing and/or newly forming blood vessels, and histology. VEGF mRNA was found to be overexpressed by retinal pigment epithelial cells and resulted in leaky blood vessels at 10 days postinjection, which was maintained for up to 31 days postinjection. By 80 days postinjection, new blood vessels had originated from the choriocapillaris, grown through the Bruch's membrane to the subretinal space, and disrupted the retinal pigment epithelium. This ultimately led to the formation of choroidal neovascular membranes and the death of overlying photoreceptor cells. By controlling the amount of virus delivered to the subretinal space, we were able to influence the severity and extent of the resulting choroidal neovascularization. These results show that even temporary overexpression of VEGF in retinal pigment epithelial cells is sufficient to induce choroidal neovascularization in the rat eye.
Abstract: Summary This paper describes a technique for computing approximate maximum pseudolikelihood estimates of the parameters of a spatial point process. The method is an extension of Berman & Turner’s (1992) device for maximizing the likelihoods of inhomogeneous spatial Poisson processes. For a very wide class of spatial point process models the likelihood is intractable, while the pseudolikelihood is known explicitly, except for the computation of an integral over the sampling region. Approximation of this integral by a finite sum in a special way yields an approximate pseudolikelihood which is formally equivalent to the (weighted) likelihood of a loglinear model with Poisson responses. This can be maximized using standard statistical software for generalized linear or additive models, provided the conditional intensity of the process takes an ‘exponential family’ form. Using this approach a wide variety of spatial point process models of Gibbs type can be fitted rapidly, incorporating spatial trends, interaction between points, dependence on spatial covariates, and mark information.
TL;DR: The existing theory that has been developed for 1D signals is extended to allow the calculation of phase congruency in 2D images and it is argued that high-pass filtering should be used to obtain image information at different scales.
Abstract: Phase congruency is a low-level invariant property of image features. Interest in low-level image invariants has been limited. This is surprising, considering the fundamental importance of being able to obtain reliable results from low-level image operations in order to successfully perform any higher level operations. However, an impediment to the use of phase congruency to detect features has been its sensitivity to noise. This paper extends the theory behind the calculation of phase congruency in a number of ways. An effective method of noise compensation is presented that only assumes that the noise power spectrum is approximately constant. Problems with the localization of features are addressed by introducing a new, more sensitive measure of phase congruency. The existing theory that has been developed for 1D signals is extended to allow the calculation of phase congruency in 2D images. Finally, it is argued that high-pass filtering should be used to obtain image information at different scales. With this approach, the choice of scale only affects the relative significance of features without degrading their localization.
TL;DR: The data suggest that there is a correlation among the number of CD8+ T cells, in vivo CTL function, and IFN-γ production, with no evidence of a partial or nonresponsive phenotype among tetramer-positive cells.
Abstract: A number of tumor studies have indicated a link between CD4 help and the magnitude and persistence of CTL activity; however, the mechanisms underlying this have been largely unclear. To evaluate and determine the mechanisms by which CD4(+) T cells synergize with CD8(+) T cells to prevent tumor growth, we used the novel technique of monitoring in vivo CTL by labeling target cells with CFSE. This approach was supported by the direct visualization of CTL using peptide-MHC tetramers to follow tumor-specific T cells. The data presented demonstrate that while cotransfer of Ag-specific CD4(+) T cells was not required for the generation of CTLs, because adoptive transfer of CD8(+) T cells alone was sufficient, CD4(+) T cells were required for the maintenance of CD8(+) T cell numbers. Our data suggest that there is a correlation among the number of CD8(+) T cells, in vivo CTL function, and IFN-gamma production, with no evidence of a partial or nonresponsive phenotype among tetramer-positive cells. We also show that CD4(+) T cells are required for CD8(+) T cell infiltration of the tumor.
TL;DR: Microbial catabolic evenness was assessed by measuring the short-term respiration responses of soil to a range of simple organic compounds and found that land-uses that deplete organic C stocks in soils may cause declines in the catabolic diversity of soil microbial communities.
Abstract: An understanding of the main factors influencing microbial diversity in soils is necessary to predict the eAects of current landuse trends on terrestrial diversity. We used microbial catabolic evenness as a measure of one component of soil microbial diversity. Catabolic evenness was assessed by measuring the short-term respiration responses of soil to a range of simple organic compounds. DiAerences in catabolic evenness between pasture and other land-uses on matched soils were related to diAerences in organic C pools (total organic C, microbial biomass C, and potentially mineralizable C). This approach enabled comparison of land-use eAects on organic C pools in relation to catabolic evenness without the eAects of soil type. In general, microbial catabolic evenness was greatest in soils under pasture and indigenous vegetation (range: 19.7‐23.3), and least in soils under cereal/maize/horticultural cropping (range: 16.4‐19.6). Soils under mixed cropping land-uses had catabolic evenness that ranged between these extremes (range: 17.7‐20.5), but under pine forestry there was no characteristic level of evenness (range: 15.1‐ 22.3). Catabolic evenness correlated poorly with the absolute values of soil organic C pools (r 2 < 0.36). However, across a range of paired comparisons between pasture and other land-uses, greater diAerences in microbial catabolic evenness corresponded with greater diAerences in organic C (r 2 =0.76) and, to a lesser degree, with diAerences in microbial biomass C (r 2 < 0.45) or potentially mineralizable C (r 2 < 0.13). Therefore, land-uses that deplete organic C stocks in soils may cause declines in the catabolic diversity of soil microbial communities. Although the implications of this for microbial processes are unknown, maintenance of soil organic C may be important for preservation of microbial diversity. # 2000 Elsevier Science Ltd. All rights reserved.
TL;DR: The purpose of this review is to examine the suitability of location-allocation models for designing health care systems and their relevance to overall development problems in such countries.
TL;DR: The sub-apical decline in ROL appeared to coincide with the appearance of aerenchyma in the cortex but thin walled ‘passage areas’ (windows) in the hypodermal/epidermal cylinder persisted locally and remained leaky to oxygen to some degree.
TL;DR: Mole characterization of morphologically identical isolates from humans and numerous other species of mammals has confirmed the heterogeneity of this parasite and provided a basis for a clearer understanding of the taxonomy and zoonotic potential of Giardia.
TL;DR: Sequence analysis of two genes located in the critical region identified the founder HMSNL mutation: a premature-termination codon at position 148 of the N-myc downstream-regulated gene 1 (NDRG1).
Abstract: Hereditary motor and sensory neuropathies, to which Charcot-Marie-Tooth (CMT) disease belongs, are a common cause of disability in adulthood. Growing awareness that axonal loss, rather than demyelination per se, is responsible for the neurological deficit in demyelinating CMT disease has focused research on the mechanisms of early development, cell differentiation, and cell-cell interactions in the peripheral nervous system. Autosomal recessive peripheral neuropathies are relatively rare but are clinically more severe than autosomal dominant forms of CMT, and understanding their molecular basis may provide a new perspective on these mechanisms. Here we report the identification of the gene responsible for hereditary motor and sensory neuropathy–Lom (HMSNL). HMSNL shows features of Schwann-cell dysfunction and a concomitant early axonal involvement, suggesting that impaired axon-glia interactions play a major role in its pathogenesis. The gene was previously mapped to 8q24.3, where conserved disease haplotypes suggested genetic homogeneity and a single founder mutation. We have reduced the HMSNL interval to 200 kb and have characterized it by means of large-scale genomic sequencing. Sequence analysis of two genes located in the critical region identified the founder HMSNL mutation: a premature-termination codon at position 148 of the N-myc downstream-regulated gene 1 (NDRG1). NDRG1 is ubiquitously expressed and has been proposed to play a role in growth arrest and cell differentiation, possibly as a signaling protein shuttling between the cytoplasm and the nucleus. We have studied expression in peripheral nerve and have detected particularly high levels in the Schwann cell. Taken together, these findings point to NDRG1 having a role in the peripheral nervous system, possibly in the Schwann-cell signaling necessary for axonal survival.