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The Materials Management and Minimization program is developing fuel designs to replace highly enriched fuel with fuels of low enrichment. Swelling is an important irradiation behavior that needs to be well understood. Data from high resolution thickness measurements performed on U-7Mo dispersion fuel plates with Al-Si alloy matrices that were irradiated at high power is sparse. This paper reports the results of detailed thickness measurements performed on two dispersion fuel plates that were irradiated at relatively high power to high fission densities in the Advanced Test Reactor in the same RERTR-9B experiment. Both plates were irradiated to similar fission densities, but one was irradiated at a higher power than the other. The goal of this work is to identify any differences in the swelling behavior when fuel plates are irradiated at different powers to the same fission densities. Based on the results of detailed thickness measurments, more swelling occurs when a U-7Mo dispersion fuel with Al-3.5Si matrix is irradiated to a high fission density at high power compared to one irradiated at a lower power to high fission density.

Introduction The impact of time to treatment on clinical outcome is an established precept in infectious disease but is not established in peritoneal dialysis–related peritonitis (PDRP). Methods In a prospective multicenter study of PDRP, symptom-to-contact time (SC), contact-to-treatment time (CT), defined as the time from health care presentation to initial antibiotic, and symptom-to-treatment time (ST) were determined. Results One hundred sixteen patients had 159 episodes of PDRP. Median SC for all episodes was 5.0 hours (first to third quartile [Q1–Q3]: 1.3–13.9); CT, 2.3 hours (Q1–Q3: 1.2–4.0); and ST, 9.0 hours (Q1–Q3: 4.7–25.3). Thirty-eight (23.9%) patient episodes (28 catheter removals and 10 deaths) met the primary composite outcome of PD failure at 30 days (PD-fail). The risk of PD-fail increased by 5.5% for each hour of delay of administration of antibiotics (odds ratio [OR] for CT: 1.055; 95% confidence interval [CI]: 1.005–1.109; P = 0.032). Neither SC (OR: 1.00; 95% CI: 0.99–1.01; P = 0.74) nor ST (OR: 1.00; 95% CI: 0.99–1.01; P = 0.48) was associated with PD-fail. In a multivariable analysis, only CT for presentation to a hospital-based facility compared with a community facility (OR: 1.068; 95% CI: 1.013–1.126; P = 0.015) and female sex (OR: 2.4; 95% CI: 1.1–5.4; P = 0.027) were independently associated with PD-fail. Each hour of delay in administering antibacterial therapy from the time of presentation to a hospital facility increased the risk of PD failure or death by 6.8%. Discussion Strategies targeted to expedited antibiotic treatment should be implemented to improve outcomes from PDRP.

The interaction between perception and action represents one of the pillars of human evolutionary success. Our interactions with the surrounding world involve a variety of behaviors, almost always including movements of the eyes and hands. Such actions rely on neural mechanisms that must process an enormous amount of information in order to generate appropriate motor commands. Yet, compared to the great advancements in the field of perception for cognition, the neural underpinnings of how we control our movements, as well as the interactions between perception and motor control, remain elusive. With this research topic we provide a framework for: (1) the perception of real objects and shapes using visual and haptic information, (2) the reference frames for action and perception, and (3) how perceived target properties are translated into goal-directed actions and object manipulation. The studies in this special issue employ a variety of methodologies that include behavioral kinematics, neuroimaging, transcranial magnetic stimulation, and patient cases. Here we provide a brief summary and commentary on the articles included in this research topic.

Australia’s “Direct Action” climate change policy relies on purchasing greenhouse gas abatement from projects undertaking approved abatement activities. Management of soil organic carbon (SOC) in agricultural soils is an approved activity, based on the expectation that land use change can deliver significant changes in SOC. However, there are concerns that climate, topography and soil texture will limit changes in SOC stocks. This work analyses data from 1482 sites surveyed across the major agricultural regions of Eastern Australia to determine the relative importance of land use vs. other drivers of SOC. Variation in land use explained only 1.4% of the total variation in SOC, with aridity and soil texture the main regulators of SOC stock under different land uses. Results suggest the greatest potential for increasing SOC stocks in Eastern Australian agricultural regions lies in converting from cropping to pasture on heavy textured soils in the humid regions.

Contains fulltext : 63834.pdf (Publisher’s version ) (Open Access) As we move through space, stationary objects around us show motion parallax: their directions relative to us change at different rates, depending on their distance. Does the brain incorporate parallax when it updates its stored representations of space? We had subjects fixate a distant target and then we flashed lights, at different distances, onto the retinal periphery. Subjects translated sideways while keeping their gaze on the distant target, and then they looked to the remembered location of the flash. Their responses corrected almost perfectly for parallax: they turned their eyes farther for nearer targets, in the predicted nonlinear patterns. Computer simulations suggest a neural mechanism in which feedback about self-motion updates remembered locations of objects within an internal map of three-dimensional visual space.

Increasing soil organic carbon (SOC) storage in agricultural soils through changes to management may help to mitigate rising greenhouse gas emissions and sustain agricultural productivity and environmental conditions. However, in order to improve assessment of the potential for increasing SOC storage in the agricultural lands of Victoria, Australia, further information is required on current SOC levels and how they are related to environmental conditions, soil properties and agricultural management. Therefore, we measured stocks of SOC at 615 sites in pasture and cropping systems in Victoria, encompassing eight regions, five soil orders and four management classes (continuous cropping, crop–pasture rotation, sheep or beef pasture, and dairy pasture), and explored relationships between the C stocks and environment, soil and management. The results showed an extremely wide range in SOC, from 2 to 239 t C/ha (0–30 cm). Most of this variation was attributable to climate; almost 80% of the variation in SOC stock was related to annual rainfall or vapour pressure deficit (i.e. humidity). Texture-related soil properties accounted for a small, additional amount of variation in SOC. After accounting for climate, differences in SOC between management classes were small and often not significant. Management practices such as stubble retention, minimum cultivation, perennial pasture species, rotational grazing and fertiliser inputs were not significantly related to SOC stock. The relationships between SOC and environment, soil and management were scale-dependent. Within individual regions, the apparent influence of climate and soil properties on SOC stock varied, and in some regions, much of the variation in SOC stock remained unexplained. The results suggest that, across Victoria, there is a general hierarchy of influence on SOC stock: climate > soil properties > management class > management practices.

This study demonstrates the feasibility of using remote sensing in the assessment of landscape visual quality. Remotely sensed data, together with a digital elevation model, are used to replicate an earlier, traditional study. Comparisons are drawn between the two studies at each of two phases. In Stage 1, the data are used to delineate homogeneous landscape units, which previously were defined using manual overlay mapping techniques and field checking. In Stage 2, new methods for assessing the visual assessment criteria are developed so that they can be measured and scored by computer analysis of the satellite information and the digital elevation model rather than extensive fieldwork. In addition, this project demonstrates that considerable savings in time can be achieved using this approach.

It was recently shown that expert face perception relies on the extraction of horizontally oriented visual cues. Picture-plane inversion was found to eliminate horizontal, suggesting that this tuning contributes to the specificity of face processing. The present experiments sought to determine the spatial frequency (SF) scales supporting the horizontal tuning of face perception. Participants were instructed to match upright and inverted faces that were filtered both in the frequency and orientation domains. Faces in a pair contained horizontal or vertical ranges of information in low, middle, or high SF (LSF, MSF, or HSF). Our findings confirm that upright (but not inverted) face perception is tuned to horizontal orientation. Horizontal tuning was the most robust in the MSF range, next in the HSF range, and absent in the LSF range. Moreover, face inversion selectively disrupted the ability to process horizontal information in MSF and HSF ranges. This finding was replicated even when task difficulty was equated across orientation and SF at upright orientation. Our findings suggest that upright face perception is tuned to horizontally oriented face information carried by intermediate and high SF bands. They further indicate that inversion alters the sampling of face information both in the orientation and SF domains.

Despite considerable research, predicting how soil organic carbon (SOC) in grain production systems will respond to conservation management practices, such as reduced tillage, residue retention and alternative rotations, remains difficult because of the slowness of change and apparent site specificity of the effects. We compared SOC stocks (equivalent soil mass to ~0–0.3 m depth) under various tillage, residue management and rotation treatments in three long-term (12-, 28- and 94-year-old) field experiments in two contrasting environments (Mallee and Wimmera regions). Our hypotheses were that SOC stocks are increased by: (1) minimum tillage rather than traditional tillage; (2) continuous cropping, rather than crop–fallow rotations; and (3) phases of crop or pasture legumes in rotations, relative to continuous cropping with cereals. We found that zero tillage and stubble retention increased SOC in some circumstances (by up to 1.5 Mg C ha–1, or 8%) but not in others. Inclusion of bare fallow in rotations reduced SOC (by 1.4–2.4 Mg C ha–1, or 8–12%) compared with continuous cropping. Including a pulse crop (field pea, where the grain was harvested) in rotations also increased SOC in some instances (by ~6–8 Mg C ha–1, or 29–35%) but not in others. Similarly, leguminous pasture (medic or lucerne) phases in rotations either increased SOC (by 3.5 Mg C ha–1, or 21%) or had no significant effect compared with continuous wheat. Inclusion of a vetch green manure or unfertilised oat pasture in the rotation did not significantly increase SOC compared with continuous wheat. The responses in SOC to these management treatments were likely to be due, in part, to differences in nitrogen and water availability (and their effects on carbon inputs and decomposition) and, in part, to other, unidentified, interactions. We conclude that the management practices examined in the present study may not reliably increase SOC on their own, but that significant increases in SOC are possible under some circumstances through the long-term use of multiple practices, such as stubble retention + zero tillage + legume N input + elimination of fallow. The circumstances under which increases in SOC can be achieved require further investigation.

This project focused on extension of a generalized state-vector model developed by Crawford-Brown and Hofmann (1-4). The model incorporates phenomena such as DNA damage and repair, intercellular communication mechanisms, both spontaneous and radiation-induced cell death and cell division, to predict cellular transformation following exposure to ionizing radiation. Additionally, this model may be simulated over time periods that correspond to the temporal scale of biological mechanisms. The state-vector model has been shown to generally reproduce transformation frequency patterns for in vitro studies (2), but still significantly underpredicted in vivo cancer incidence data at the higher doses for high-LET radiations when biologically realistic rate constants for cell killing are included (1). Mebust et al. (1) claimed that one reason for this underprediction might be that the model's ability to fit the in vitro data is due in part to compensating errors that only reveal themselves when the more complex in vivo and epidemiological data are considered. This implies that the original in vitro model may be based on incomplete assumptions regarding the underlying biological mechanisms. The present research considered this explanation for the case of low LET radiation. An extension of the in vitro state-vector model was tested that includes additional biological mechanisms in order to improve model predictions with respect to dose-response data on in vitro oncogenic transformation of C3H10T1/2 mouse fibroblast cells exposed to acute doses of X-radiation (5). These data display a plateau of transformation frequency per surviving cell in the X-ray dose range of 0.1 to 1 Gy, with an increase in transformation frequency at higher acute doses. To reproduce these trends in the data, additional biological processes were formulated mathematically and incorporated into the existing model as parameters whose values could be adjusted and tested by an optimization method (genetic algorithm). The model extension presented here includes many of the same biological phenomena as the original state-vector model, though some mathematical representations of these mechanisms have been adjusted and new pathways in which these events occur have been included. In addition to these original processes, this state-vector model extension incorporates: (1) pre-irradiation background transformation, (2) the bystander effect on cell killing and (3) an explicit representation for compensatory proliferation. These experimentally recognized biological mechanisms are established as important processes within carcinogenesis and their ability to improve model predictions should be explored.

Contains fulltext : 63429.pdf (Publisher’s version ) (Open Access) Single-unit recordings have identified a region in the posterior parietal cortex (PPC) of the monkey that represents and updates visual space in a gaze-centered frame. Here, using event-related functional magnetic resonance imaging, we identified an analogous bilateral region in the human PPC that shows contralateral topography for memory-guided eye movements and arm movements. Furthermore, when eye movements reversed the remembered horizontal target location relative to the gaze fixation point, this PPC region exchanged activity across the two cortical lobules. This shows that the human PPC dynamically updates the spatial goals for action in a gaze-centered frame.

Contains fulltext : 197383.pdf (Publisher’s version ) (Open Access)