931 research outputs found
A preliminary training guide for utilizing high-altitude, color-infrared photography in compiling soil maps
Instruction for acquiring and analytically processing small-scale color-infrared photography to perform a soil resources inventory over forests of the southern U.S. is provided. Planning the project; acquiring aerial photography, materials, equipment and supplemental data; and preparing the photography for analysis are discussed. The procedures for preparing ancillary and primary component overlays are discussed. The use of correlation charts and dichotomous keys for mountain landforms, water regime, and vegetation is explained
Multiscale Discriminant Saliency for Visual Attention
The bottom-up saliency, an early stage of humans' visual attention, can be
considered as a binary classification problem between center and surround
classes. Discriminant power of features for the classification is measured as
mutual information between features and two classes distribution. The estimated
discrepancy of two feature classes very much depends on considered scale
levels; then, multi-scale structure and discriminant power are integrated by
employing discrete wavelet features and Hidden markov tree (HMT). With wavelet
coefficients and Hidden Markov Tree parameters, quad-tree like label structures
are constructed and utilized in maximum a posterior probability (MAP) of hidden
class variables at corresponding dyadic sub-squares. Then, saliency value for
each dyadic square at each scale level is computed with discriminant power
principle and the MAP. Finally, across multiple scales is integrated the final
saliency map by an information maximization rule. Both standard quantitative
tools such as NSS, LCC, AUC and qualitative assessments are used for evaluating
the proposed multiscale discriminant saliency method (MDIS) against the
well-know information-based saliency method AIM on its Bruce Database wity
eye-tracking data. Simulation results are presented and analyzed to verify the
validity of MDIS as well as point out its disadvantages for further research
direction.Comment: 16 pages, ICCSA 2013 - BIOCA sessio
Exponential Distribution of Locomotion Activity in Cell Cultures
In vitro velocities of several cell types have been measured using computer
controlled video microscopy, which allowed to record the cells' trajectories
over several days. On the basis of our large data sets we show that the
locomotion activity displays a universal exponential distribution. Thus, motion
resulting from complex cellular processes can be well described by an
unexpected, but very simple distribution function. A simple phenomenological
model based on the interaction of various cellular processes and finite ATP
production rate is proposed to explain these experimental results.Comment: 4 pages, 3 figure
Simultaneous free-volume modeling of the self-diffusion coefficient and dynamic viscosity at high pressure
International audienceA free-volume model of the dynamic viscosity and the self-diffusion coefficients was discussed. The temperature-pressure variations of the dynamic viscosity and the self-diffusion coefficients of small molecules were predicted. The compounds, carbon tetrachloride, cyclohexane, benzene, chlorotrifluoromethane, tetramethylsilane and methylcyclohexane were used for the investigation. The relation between microstructure, free volume and different complex thermophysical properties were emphasized by the model
Simulating carbon capture by enhanced weathering with global croplands: an overview of key processes highlighting areas of future model development
Enhanced weathering (EW) aims to amplify a natural sink for CO2 by incorporating
powdered silicate rock with high reactive surface area into
agricultural soils. The goal is to achieve rapid dissolution of minerals and
release of alkalinity with accompanying dissolution of CO2 into soils and drainage
waters. EW could counteract phosphorus limitation and greenhouse gas
(GHG) emissions in tropical soils, and soil acidification, a common agricultural
problem studied with numerical process models over several decades.
Here, we review the processes leading to soil acidification in croplands and
how the soil weathering CO2 sink is represented in models. Mathematical
models capturing the dominant processes and human interventions governing
cropland soil chemistry and GHG emissions neglect weathering, while
most weathering models neglect agricultural processes. We discuss current
approaches to modelling EW and highlight several classes of model having
the potential to simulate EW in croplands. Finally, we argue for further integration
of process knowledge in mathematical models to capture feedbacks
affecting both longer-term CO2 consumption and crop growth and yields
Recent Developments and Applications of the HYDRUS Computer Software Packages
The HYDRUS-1D and HYDRUS (2D/3D) computer software packages are widely used finite-element models for simulating the one- and two- or three-dimensional movement of water, heat, and multiple solutes in variably saturated media, respectively. In 2008, Šimůnek et al. (2008b) described the entire history of the development of the various HYDRUS programs and related models and tools such as STANMOD, RETC, ROSETTA, UNSODA, UNSATCHEM, HP1, and others. The objective of this manuscript is to review selected capabilities of HYDRUS that have been implemented since 2008. Our review is not limited to listing additional processes that were implemented in the standard computational modules, but also describes many new standard and nonstandard specialized add-on modules that significantly expanded the capabilities of the two software packages. We also review additional capabilities that have been incorporated into the graphical user interface (GUI) that supports the use of HYDRUS (2D/3D). Another objective of this manuscript is to review selected applications of the HYDRUS models such as evaluation of various irrigation schemes, evaluation of the effects of plant water uptake on groundwater recharge, assessing the transport of particle-like substances in the subsurface, and using the models in conjunction with various geophysical methods
Conclusion: Reflecting on Studying Evidence Use from a Public Policy Perspective
This final chapter reflects on the insights provided by the case studies that constitute this volume, focussing on the key questions which informed the broader research programme from which the cases arise: what does it mean to use evidence effectively to inform health policymaking?; and how do political and institutional factors shape the specific forms of evidence use that arise in different contexts? It discusses the circumstances in which instrumental or strategic uses of evidence were seen; as well as synthesising insights about the ways in which political contestation, the framing and construction of policy problems and their solutions, and different institutional arrangements for policy delivery shape evidence use in different policy contexts. The chapter concludes by considering future areas of research in this field to provide further insights into the use of evidence for health policymaking from a public policy perspective
Damaging real lives through obstinacy: re-emphasising why significance testing is wrong
This paper reminds readers of the absurdity of statistical significance testing, despite its continued widespread use as a supposed method for analysing numeric data. There have been complaints about the poor quality of research employing significance tests for a hundred years, and repeated calls for researchers to stop using and reporting them. There have even been attempted bans. Many thousands of papers have now been written, in all areas of research, explaining why significance tests do not work. There are too many for all to be cited here. This paper summarises the logical problems as described in over 100 of these prior pieces. It then presents a series of demonstrations showing that significance tests do not work in practice. In fact, they are more likely to produce the wrong answer than a right one. The confused use of significance testing has practical and damaging consequences for people's lives. Ending the use of significance tests is a pressing ethical issue for research. Anyone knowing the problems, as described over one hundred years, who continues to teach, use or publish significance tests is acting unethically, and knowingly risking the damage that ensues
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