1,762 research outputs found

    Lattice structure and magnetization of LaCoO3 thin films

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    We investigate the structure and magnetic properties of thin films of the LaCoO3_{3} compound. Thin films are deposited by pulsed laser deposition on various substrates in order to tune the strain from compressive to tensile. Single-phase (001) oriented LaCoO3_{3} layers were grown on all substrates despite large misfits. The tetragonal distortion of the films covers a wide range from -2% to 2.8%. Our LaCoO3_{3} films are ferromagnetic with Curie temperature around 85 K, contrary to the bulk. The total magnetic moment is below 1μB1\mu_{B}/Co3+^{3+}, a value relatively small for an exited spin-state of the Co3+^{3+} ions, but comparable to values reported in literature. A correlation of strain states and magnetic moment of Co3+^{3+} ions in LaCoO3_{3} thin films is observed.Comment: submitted tu European Phys. J.

    Survival of Northern Bobwhite on Hunted and Nonhunted Study Areas in the North Carolina Sandhills

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    Radio-tagged northern bobwhite (Colinus virginianus) were monitored in the Sandhills region of North Carolina to investigate the influences of hunting on seasonal survival. We used the Kaplan-Meier product limit method with staggered entry design to calculate survival estimates and distributions for 79 radio-tagged bobwhite representing 33 coveys during November-February 1987-89. Estimated winter survival rates for year 1 (59%) and for pooled years (67%) in the nonhunted study areas were greater than in the hunted areas (31 and 45%, respectively; P \u3c 0.05). Survival trends for the second winter were again greater in the nonhunted study areas (7 4%) but not different than hunted study areas (63%; P \u3e 0.05). Avian predation was the major proximate cause of mortality, accounting for 66% of the known losses. Summer whistle count surveys indicated that nonhunted study areas contained more (P\u3c 0.05) whistling bobwhite per station than hunted areas following winter hunting seasons

    The Univariate Marginal Distribution Algorithm Copes Well With Deception and Epistasis

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    In their recent work, Lehre and Nguyen (FOGA 2019) show that the univariate marginal distribution algorithm (UMDA) needs time exponential in the parent populations size to optimize the DeceptiveLeadingBlocks (DLB) problem. They conclude from this result that univariate EDAs have difficulties with deception and epistasis. In this work, we show that this negative finding is caused by an unfortunate choice of the parameters of the UMDA. When the population sizes are chosen large enough to prevent genetic drift, then the UMDA optimizes the DLB problem with high probability with at most λ(n2+2elnn)\lambda(\frac{n}{2} + 2 e \ln n) fitness evaluations. Since an offspring population size λ\lambda of order nlognn \log n can prevent genetic drift, the UMDA can solve the DLB problem with O(n2logn)O(n^2 \log n) fitness evaluations. In contrast, for classic evolutionary algorithms no better run time guarantee than O(n3)O(n^3) is known (which we prove to be tight for the (1+1){(1+1)} EA), so our result rather suggests that the UMDA can cope well with deception and epistatis. From a broader perspective, our result shows that the UMDA can cope better with local optima than evolutionary algorithms; such a result was previously known only for the compact genetic algorithm. Together with the lower bound of Lehre and Nguyen, our result for the first time rigorously proves that running EDAs in the regime with genetic drift can lead to drastic performance losses

    Habitat Selection and Post-Release Movement of Reintroduced Brown Treecreeper Individuals in Restored Temperate Woodland

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    It is essential to choose suitable habitat when reintroducing a species into its former range. Habitat quality may influence an individual's dispersal decisions and also ultimately where they choose to settle. We examined whether variation in habitat quality (quantified by the level of ground vegetation cover and the installation of nest boxes) influenced the movement, habitat choice and survival of a reintroduced bird species. We experimentally reintroduced seven social groups (43 individuals) of the brown treecreeper (Climacteris picumnus) into two nature reserves in south-eastern Australia. We radio-tracked 18 brown treecreepers from release in November 2009 until February 2010. We observed extensive movements by individuals irrespective of the release environment or an individual's gender. This indicated that individuals were capable of dispersing and actively selecting optimum habitat. This may alleviate pressure on wildlife planners to accurately select the most optimum release sites, so long as the species' requirements are met. There was significant variation in movement between social groups, suggesting that social factors may be a more important influence on movement than habitat characteristics. We found a significant effect of ground vegetation cover on the likelihood of settlement by social groups, with high rates of settlement and survival in dry forests, rather than woodland (where the species typically resides), which has implications for the success of woodland restoration. However, overall the effects of variation in habitat quality were not as strong as we had expected, and resulted in some unpredicted effects such as low survival and settlement in woodland areas with medium levels of ground vegetation cover. The extensive movement by individuals and unforeseen effects of habitat characteristics make it difficult to predict the outcome of reintroductions, the movement behaviour and habitat selection of reintroduced individuals, particularly when based on current knowledge of a species' ecology.The project has been made possible by funding from:Birding NSW (www.birdingnsw.org.au), Birdlife Australia – Stuart Leslie Bird Research Award (www.birdlife.org.au), Canberra Ornithologists Group, Canberra Birds Conservation Fund (www.canberrabirds.org.au),The Conservation and Landscape Ecology Group within the Fenner School of Environment and Society at The Australian National University (http://fennerschool-research.anu.edu.au/​cle/), The Fenner School of Environment and Society at The Australian National University (http://fennerschool.anu.edu.au/), The Foundation for National Parks and Wildlife (www.fnpw.org.au), Gould League of NSW 2010 Centenary Year Cayley Memorial Scholarship (www.gould.edu.au), The Mulligans Flat-Goorooyarroo Woodland Experiment (ARC Linkage Project LP0561817) (http://www.mfgowoodlandexperiment.org.au​/),The Norman Wettenhall Foundation (reference 20108002) (www.nwf.org.au), In-kind contribution was greatly appreciated from CSIRO Ecosystem Sciences (http://www.csiro.au/Organisation-Structu​re/Divisions/Ecosystem-Sciences.aspx) and The Parks and Conservation Service within the Australian Capital Territory Government Department of Territory and Municipal Services (http://www.tams.act.gov.au/play/pcl). One field assistant was employed (Jenny Newport) using funds from Conservation and Landscape Ecology Group and the Mulligans Flat-Goorooyarroo Woodland Experiment to assist in collecting data obtained through radio-tracking reintroduced brown treecreepers

    Habitat Selection and Behaviour of a Reintroduced Passerine: Linking Experimental Restoration, Behaviour and Habitat Ecology

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    Habitat restoration can play an important role in recovering functioning ecosystems and improving biodiversity. Restoration may be particularly important in improving habitat prior to species reintroductions. We reintroduced seven brown treecreeper (Climacteris picumnus) social groups into two nature reserves in the Australian Capital Territory in south-eastern Australia. This study provided a unique opportunity to understand the interactions between restoration ecology, behavioural ecology and habitat ecology. We examined how experimental restoration treatments (addition of coarse woody debris, variations in ground vegetation cover and nest box installation) influenced the behaviour and microhabitat use of radio-tracked individuals to evaluate the success of restoration treatments. The addition of coarse woody debris benefited the brown treecreeper through increasing the probability of foraging on a log or on the ground. This demonstrated the value of using behaviour as a bio-indicator for restoration success. Based on previous research, we predicted that variations in levels of ground vegetation cover would influence behaviour and substrate use, particularly that brown treecreepers would choose sites with sparse ground cover because this allows better access to food and better vigilance for predators. However, there was little effect of this treatment, which was likely influenced by the limited overall use of the ground layer. There was also little effect of nest boxes on behaviour or substrate use. These results somewhat confound our understanding of the species based on research from extant populations. Our results also have a significant impact regarding using existing knowledge on a species to inform how it will respond to reintroduction and habitat restoration. This study also places great emphasis on the value of applying an experimental framework to ecological restoration, particularly when reintroductions produce unexpected outcomes.The project has been made possible by funding from Birding NSW (www.birdingnsw.org.au), Birdlife Australia – Stuart Leslie Bird Research Award (www.birdlife.org.au), Canberra Ornithologists Group, Canberra Birds Conservation Fund (www.canberrabirds.org.au), the Conservation and Landscape Ecology Group within the Fenner School of Environment and Society at The Australian National University (http://fennerschool-research.anu.edu.au/cle/), the Fenner School of Environment and Society at The Australian National University (http://fennerschool.anu.edu.au/), the Foundation for National Parks and Wildlife (www.fnpw.org.au), Gould League of NSW 2010 Centenary Year Cayley Memorial Scholarship (www.gould.edu.au), the Mulligans Flat-Goorooyarroo Woodland Experiment (ARC Linkage Project LP0561817) (http://www.mfgowoodlandexperiment.org.au/), and the Norman Wettenhall Foundation (reference 20108002) (www.nwf.org.au). In-kind contribution was greatly appreciated from CSIRO Ecosystem Sciences (http://www.csiro.au/Organisation-Structure/Divisions/Ecosystem-Sciences.aspx) and The Parks and Conservation Service within the Australian Capital Territory Government Department of Territory and Municipal Services (http://www.tams.act.gov.au/parks-recreation). One field assistant was employed (Jenny Newport) using funds from Conservation and Landscape Ecology Group and the Mulligans Flat-Goorooyarroo Woodland Experiment to assist in collecting data obtained through radio-tracking reintroduced brown treecreepers. Otherwise, individuals that were employed or contracted by the funders (other than the named authors) did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Critical conditions for the wetting of soils

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    The wettability of soil is of great importance for plants and soil biota and in determining whether flooding and soil erosion will occur. The analysis used in common measurements of soil hydrophobicity makes the assumption that water always enters soils if the average contact angle between the soil and water is 90 degrees or lower; these tests have been used for decades. The authors show theoretically and experimentally that water cannot enter many soils unless the contact angle is considerably lower than this, down to approximately 50 degrees. This difference generates serious errors in determining and modeling soil wetting behavior

    Rigorous treatment of electrostatics for spatially varying dielectrics based on energy minimization

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    A novel energy minimization formulation of electrostatics that allows computation of the electrostatic energy and forces to any desired accuracy in a system with arbitrary dielectric properties is presented. An integral equation for the scalar charge density is derived from an energy functional of the polarization vector field. This energy functional represents the true energy of the system even in non-equilibrium states. Arbitrary accuracy is achieved by solving the integral equation for the charge density via a series expansion in terms of the equation's kernel, which depends only on the geometry of the dielectrics. The streamlined formalism operates with volume charge distributions only, not resorting to introducing surface charges by hand. Therefore, it can be applied to any spatial variation of the dielectric susceptibility, which is of particular importance in applications to biomolecular systems. The simplicity of application of the formalism to real problems is shown with analytical and numerical examples.Comment: 27 pages, 5 figure

    Experience in hepatic resection for metastatic colorectal cancer: Analysis of clinical and pathologic risk factors

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    Background. The selection of patients for resective therapy of hepatic colorectal metastases remains controversial. A number of clinical and pathologic prognostic risk factors have been variably reported to influence survival. Methods. Between January 1981 and December 1991, 204 patients underwent curative hepatic resection for metastatic colorectal cancer. Fourteen clinical and pathologic determinants previously reported to influence outcome were examined retrospectively. This led to a proposed TNM staging system for metastatic colorectal cancer (mTNM). Results. No operative deaths occurred (death within 1 month). Overall 1-, 3-, and 5-year survivals were 91%, 43%, and 32%, respectively. Gender, Dukes' classification, site of primary colorectal cancer, histologic differentiation, size of metastatic tumor, and intraoperative blood transfusion requirement were not statistically significant prognostic factors (p > 0.05). Age of 60 years or more, interval of 24 months or less between colorectal and hepatic resection, four or more gross tumors, bilobar involvement, positive resection margin, lymph node involvement, and direct invasion to adjacent organs were significant poor prognostic factors (p < 0.05). In the absence of nodal disease or direct invasion, patients with unilobar solitary tumor of any size, or unilobar multiple tumors of 2 cm or smaller (stages I and II) had the highest survival rates of 93% at 1 year, 68% at 3 years, and 61% at 5 years. Unilobar disease with multiple lesions greater than 2 cm (stage III) resulted in 1-, 3-, and 5-year survivals of 98%, 45%, and 28%, respectively. Patients with bilobar involvement (multiple tumors, any size, or a single large metastasis) (stage IVA) had survival rates of 88% at 1 year, 28% at 3 years, and 20% at 5 years (p < 0.00001). Patients with nodal involvement or extrahepatic disease (stage IVB) experienced the poorest outcome with 1-, 3- , and 5-year survivals of 80%, 12%, and 0%, respectively (p < 0.00001). Conclusions. The proposed mTNM staging system appears to be useful in predicting the outcomes after hepatic resection of metastatic colorectal tumors
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