39 research outputs found
Effects of Pore Walls and Randomness on Phase Transitions in Porous Media
We study spin models within the mean field approximation to elucidate the
topology of the phase diagrams of systems modeling the liquid-vapor transition
and the separation of He--He mixtures in periodic porous media. These
topologies are found to be identical to those of the corresponding random field
and random anisotropy spin systems with a bimodal distribution of the
randomness. Our results suggest that the presence of walls (periodic or
otherwise) are a key factor determining the nature of the phase diagram in
porous media.Comment: REVTeX, 11 eps figures, to appear in Phys. Rev.
Role of carbonate burial in Blue Carbon budgets
Calcium carbonates (CaCO 3 ) often accumulate in mangrove and seagrass sediments. As CaCO 3 production emits CO 2 , there is concern that this may partially offset the role of Blue Carbon ecosystems as CO 2 sinks through the burial of organic carbon (C org ). A global collection of data on inorganic carbon burial rates (C inorg , 12% of CaCO 3 mass) revealed global rates of 0.8 TgC inorg yr −1 and 15–62 TgC inorg yr −1 in mangrove and seagrass ecosystems, respectively. In seagrass, CaCO 3 burial may correspond to an offset of 30% of the net CO 2 sequestration. However, a mass balance assessment highlights that the C inorg burial is mainly supported by inputs from adjacent ecosystems rather than by local calcification, and that Blue Carbon ecosystems are sites of net CaCO 3 dissolution. Hence, CaCO 3 burial in Blue Carbon ecosystems contribute to seabed elevation and therefore buffers sea-level rise, without undermining their role as CO 2 sinks. © 2019, The Author(s)
Large-scale discovery of novel genetic causes of developmental disorders
Despite three decades of successful, predominantly phenotype-driven discovery of the genetic causes of monogenic disorders1, up to half of children with severe developmental disorders of probable genetic origin remain without a genetic diagnosis. Particularly challenging are those disorders rare enough to have eluded recognition as a discrete clinical entity, those with highly variable clinical manifestations, and those that are difficult to distinguish from other, very similar, disorders. Here we demonstrate the power of using an unbiased genotype-driven approach2 to identify subsets of patients with similar disorders. By studying 1,133 children with severe, undiagnosed developmental disorders, and their parents, using a combination of exome sequencing3,4,5,6,7,8,9,10,11 and array-based detection of chromosomal rearrangements, we discovered 12 novel genes associated with developmental disorders. These newly implicated genes increase by 10% (from 28% to 31%) the proportion of children that could be diagnosed. Clustering of missense mutations in six of these newly implicated genes suggests that normal development is being perturbed by an activating or dominant-negative mechanism. Our findings demonstrate the value of adopting a comprehensive strategy, both genome-wide and nationwide, to elucidate the underlying causes of rare genetic disorders
New Zealanders on the population geography of the Western Island
Article first published online: 28 JUN 2008New Zealand origin academics have played a key role in the academic study of Australia's population in the post-war period. The paper argues that New Zealanders have contributed not only to the furthering of knowledge of the processes of change in the Australian population but have been important in the teaching of population geography in Australian universities, made inputs into policy relating to population and been influential in the development of the Australian Population Association. Major contributions have been made by New Zealanders not only in the traditionally strong areas of population geography such as internal and international migration but also in the areas of fertility, mortality and ageing.Graeme Hug
Drivers of CO2 along a mangrove-seagrass transect in a tropical bay: Delayed groundwater seepage and seagrass uptake
Competition in China’s public accounting service market: evidence from newly-established branch offices
Novel use of cavity ring-down spectroscopy to investigate aquatic carbon cycling from microbial to ecosystem scales
Development of cavity ring-down spectroscopy
(CRDS) has enabled real-time monitoring of carbon stable
isotope ratios of carbon dioxide and methane in air. Here we
demonstrate that CRDS can be adapted to assess aquatic
carbon cycling processes from microbial to ecosystem scales.
We first measured in situ isotopologue concentrations of
dissolved CO2 (12CO2 and 13CO2) and CH4 (12CH4 and
13CH4) with CRDS via a closed loop gas equilibration device
during a survey along an estuary and during a 40 h time series
in a mangrove creek (ecosystem scale). A similar system was
also connected to an in situ benthic chamber in a seagrass bed
(community scale). Finally, a pulse-chase isotope enrichment
experiment was conducted by measuring real-time release of
13CO2 after addition of 13C enriched phytoplankton to exposed
intertidal sediments (microbial scale). Miller-Tans plots revealed complex transformation pathways and distinct isotopic source
values of CO2 and CH4. Calculations of δ13C-DIC based on CRDS measured δ13C-CO2 and published fractionation factors were
in excellent agreement with measured δ13C-DIC using isotope ratio mass spectroscopy (IRMS). The portable CRDS
instrumentation used here can obtain real-time, high precision, continuous greenhouse gas data in lakes, rivers, estuaries and
marine waters with less effort than conventional laboratory-based techniques