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A Partial Differential Inequality in Geological Models

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Chinese Annals of Mathematics,Series B 2007年第6期28卷 709-736页

作者： robert EYMARD Thierry GALLOUET Université Paris-Est 5 boulevard DescartesF-77454 Marne-la-ValléeFrance. Université de Marseille 39 rue Joliot CurieF-13453 Marseille 13France.

Sedimentation and erosion processes in sedimentary basins can be modeled by a parabolic equation with a limiter on the fluxes and a constraint on the time variation. This limiter happens to satisfy a stationary scalar hyperbolic inequality, within a constraint, for which the authors prove the existence and the uniqueness of the solution. Actually, this solution is shown to be the maximal element of a convenient convex set of functions. The existence proof is obtained thanks to the use of a numerical scheme.

关键词： Hyperbolic inequalities Erosion and sedimentation models

High-nickel insects and nickel hyperaccumulator plants： A review

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Insect Science 2009年第1期16卷 19-31页

作者： robert S. Boyd Department of Biological Sciences 101 Life Sciences Building Auburn University Alabama 36849-5407 USA

Insects can vary greatly in whole-body elemental concentrations. Recent investigations of insects associated with Ni hyperaccumulator plants have identified insects with relatively elevated whole-body Ni levels. Evaluation of the limited data available indicates that a whole-body Ni concentration of 500μg Ni/g is exceptional： I propose that an insect species with a mean value of 500μg Ni/g or greater, in either larval/nymphal or adult stages, be considered a ＂high-Ni insect＂. Using the 500μg Ni/g criterion, 15 species ofhigh-Ni insects have been identified to date from studies in Mpumalanga （South Africa）, New Caledonia and California （USA）. The highest mean Ni concentration reported is 3 500 μg Ni/g for nymphs of a South African Stenoscepa species （Orthoptera： Pyrgomorphidae）. The majority of high-Ni insects （66%） are heteropteran herbivores. Studies of high-Ni insect host preference indicate they are monophagous （or nearly so） on a particular Ni hyperaccumulator plant species. Much of the Ni in bodies of these insects is in their guts （up to 66%-75%）, but elevated levels have also been found in Malpighian tubules, suggesting efficient elimination as one strategy for dealing with a high-Ni diet. Tissue levels of Ni are generally much lower than gut concentrations, but up to 1200μg Ni/g has been reported from exuviae, suggesting that molting may be another pathway of Ni elimination. One ecological function of the high Ni concentration of these insects may be to defend them against natural enemies, but to date only one experimental test has supported this ＂elemental defense＂ hypothesis. Community-level studies indicate that high-Ni insects mobilize Ni into food webs but that bioaccumulation of Ni does not occur at either plant-herbivore or herbivorepredator steps. Unsurprisingly, Ni bioaccumulation indices are greater for high-Ni insects compared to other insect species that feed on Ni hyperaccumulator plants. There is some evidence of Ni mobilization into food webs

关键词： bioaccumulation elemental defense heavy metals herbivore defense,hyperaccumulation metal tolerance nickel

Statistics of Evolving Populations and Their Relevance to Flood Risk

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Journal of Earth Science 2016年第1期27卷 2-8页

作者： robert E.Criss Department of Earth and Planetary Sciences Washington University in St.Louis

Statistical methods are commonly used to evaluate natural populations and environmental variables, yet these must recognize temporal trends in population character to be appropriate in an evolving world. New equations presented here define the statistical measures of aggregate historical populations affected by linear changes in population means and standard deviations. These can be used to extract the statistical character of present-day populations, needed to define modern variability and risk, from tables of historical data that are dominated by measurements made when conditions were different. As an example, many factors such as climate change and in-channel structures are causing flood levels to rise, so realistic estimation of future flood levels must take such secular changes into account. The new equations provide estimates of water levels for ＂100-year＂ floods in the USA Midwest that are 0.5 to 2 m higher than official calculations that routinely assume population stationarity. These equations also show that flood levels will continue to rise by several centimeters per year. This rate is nearly ten times faster than the rise of sea level, and thus represents one of the fastest and most damaging rates of change that is documented by robust data.

关键词： flood risk statistical theory Mississippi River.

Weight measurement using image-based pose analysis

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Progress in Natural Science:Materials International 2008年第12期18卷 1507-1512页

作者： robert J.Sclabassi Laboratory for Computational Neuroseience Departments of NeurosurgeryElectrical & Computer Engineeringand BioengineeringUniversity of PittsburghPittsburgh 15213USA

Image-based gait analysis as a means of biometric identification has attracted much research *** of the existing methods focus on human identification,posture analysis and movement *** have been few investigations on measuring the carried load based on the carrier’s gait characteristics by automatic image ***,this measurement is very useful in a number of applications,such as the study of the carried load on the postural development of children and *** this paper,we inves- tigate how to automatically estimate the carried weight from a sequence of *** present a method to extract human gait silhouette based on an observation that humans tend to minimize the energy during *** compute several angles of body leaning and deter- mine the relationship of the carried weight,the leaning angles and the centroid location according to a human kinetic *** weight determination method has been verified successfully by experiments.

关键词： Image-based pose analysis Energy minimization Pattern recognition Load carrying measurement

Travelling Waves for a Density Dependent Diffusion Nagumo Equation over the Real Line

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Communications in Theoretical Physics 2012年第7期58卷 5-11页

作者： robert A. Van Gorder Department of Mathematics University of Central FloridaP.O.Box 161364OrlandoFL 32816-1364USA

We consider the density dependent diffusion Nagumo equation, where the diffusion coefficient is a simple power function. This equation is used in modelling electrical pulse propagation in nerve axons and in population genetics (amongst other areas). In the present paper, the δ-expansion method is applied to a travelling wave reduction of the problem, so that we may obtain globally valid perturbation solutions (in the sense that the perturbation solutions are valid over the entire infinite domain, not just locally; hence the results are a generalization of the local solutions considered recently in the literature). The resulting boundary value problem is solved on the real line subject to conditions at z →±∞. Whenever a perturbative method is applied, it is important to discuss the accuracy and convergence properties of the resulting perturbation expansions. We compare our results with those of two different numerical methods (designed for initial and boundary value problems, respectively) and deduce that the perturbation expansions agree with the numerical results after a reasonable number of iterations. Finally, we are able to discuss the influence of the wave speed c and the asymptotic concentration value α on the obtained solutions. Upon recasting the density dependent diffusion Nagumo equation as a two-dimensional dynamical system, we are also able to discuss the influence of the nonlinear density dependence (which is governed by a power-law parameter m) on oscillations of the travelling wave solutions.

关键词： density dependent diffusion equation nonlinear partial differential equation perturbation method δ-expansion method

A Study of Air/Space-borne Dual-Wavelength Radar for Estimation of Rain Profiles

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Advances in Atmospheric Sciences 2005年第6期22卷 841-851页

作者： Liang LIAO robert MENEGHINI Goddard Earth Sciences ＆ Technology Center/Caelum Greenbelt MD 20771 Code 614.6 NASA/GSFC Greenbelt MD 20771

In this study, a framework is given by which air/space-borne dual-wavelength radar data can be used to estimate the characteristic parameters of hydrometeors. The focus of the study is on the Global Precipitation Measurement （GPM） precipitation radar, a dual-wavelength radar that will operate in the Ku （13.6 GHz） and Ka （35 GHz） bands. A key aspect of the retrievals is the relationship between the differential frequency ratio （DFR） and the median volume diameter, Do, and its dependence on the phase state of the hydrometeors. It is shown that parametric plots of Do and particle concentration in the plane of the DFR and the radar reflectivity factor in the Ku band can be used to reduce the ambiguities in deriving Do from DFR. A self-consistent iterative algorithm, which does not require the use of an independent pathattenuation constraint, is examined by applying it to the apparent radar reflectivity profiles simulated from a drop size distribution （DSD） model. For light to moderate rain, the self-consistent rain profiling approach converges to the correct solution only if the same shape factor of the Gamma distributions is used both to generate and retrieve the rain profiles. On the other hand, if the shape factors differ, the iteration generally converges but not to the correct solution. To further examine the dual-wavelength techniques, the selfconsistent iterative algorithm, along with forward and backward rain profiling algorithms, are applied to measurements taken from the 2nd generation Precipitation Radar （PR-2） built by the Jet Propulsion Laboratory. Consistent with the model results, it is found that the estimated rain profiles are sensitive to the shape factor of the size distribution when the iterative, self-consistent approach is used but relatively insensitive to this parameter when the forward- and backward-constrained approaches are used.

关键词： rain rate dual-wavelength radar raindrop size distribution and GPM

Is plate tectonics needed to evolve technological species on exoplanets?

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Geoscience Frontiers 2016年第4期7卷 573-580页

作者： robert J.Stern Geoscience Department University of Texas at Dallas

As we continue searching for exoplanets, we wonder if life and technological species capable of communicating with us exists on any of them. As geoscientists, we can also wonder how important is the presence or absence of plate tectonics for the evolution of technological species. This essay considers this question, focusing on tectonically active roclw （silicate） planets, like Earth, Venus, and Mars. The development of technological species on Earth provides key insights for understanding evolution on exoplanets, including the likely role that plate tectonics may play. An Earth-sized silicate planet is likely to experience several tectonic styles over its lifetime, as it cools and its lithosphere thickens, strengthens, and becomes denser. These include magma ocean, various styles of stagnant lid, and perhaps plate tectonics. Abundant liquid water favors both life and plate tectonics. Ocean is required for early evolution of diverse single-celled organisms, then colonies of cells which specialized further to form guts, ap- pendages, and sensory organisms up to the complexity of fish （central nervous system, appendages, eyes）. Large expanses of dry land also begin in the ocean, today produced above subduction zones in juvenile arcs and by their coalescence to form continents, although it is not clear that plate tectonics was required to create continental crust on Earth. Dry land of continents is required for further evolution of technological species, where modification of appendages for grasping and manipulating, and improve- ment of eyes and central nervous system could be perfected. These bioassets allowed intelligent crea- tures to examine the night sky and wonder, the beginning of abstract thinking, including religion and science. Technology arises from the exigencies of daily living such as tool-making, agriculture, clothing, and weapons, but the pace of innovation accelerates once it is allied with science. Finally, the importance of plate tectonics for devel

关键词： Plate tectonics Exoplanets Planetary science Intelligent life

A Linearization Approach for Rational Nonlinear Models in Mathematical Physics

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Communications in Theoretical Physics 2012年第4期57卷 530-540页

作者： robert A.Van Gorder Department of Mathematics University of Central FloridaP.O.Box 161364OrlandoFL 32816-1364USA

In this paper, a novel method for linearization of rational second order nonlinear models is discussed. In particular, we discuss an application of the 5 expansion method （created to deal with problems in Quantum Field Theory） which will enable both the linearization and perturbation expansion of such equations. Such a method allows for one to quickly obtain the order zero perturbation theory in terms of certain special functions which are governed by linear equations. Higher order perturbation theories can then be obtained in terms of such special functions. One benefit to such a method is that it may be applied even to models without small physical parameters, as the perturbation is given in terms of the degree of nonlinearity, rather than any physical parameter. As an application, we discuss a method of linearizing the six Painlev~ equations by an application of the method. In addition to highlighting the benefits of the method, we discuss certain shortcomings of the method.

关键词： perturbation method Painleve equations δ-expansion nonlinear differential equations

Inhibition of sperm motility does not affect live-dead separation of bull sperm by glass beads

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Asian Journal of Andrology 2001年第3期3卷 193-198页

作者： robert H.Foote Department of Animal Science Cornell University Ithaca NY 14853-4801 USA

Aim: This study was designed to explore factors which influence binding of dead versus live sperm to glass ***: Multiple semen collections from bulls were used to explore selective filtration of bull sperm as influencedby nonlethal inhibition of sperm motility with fluoride, killing of sperm by quick-freezing, alteration of the glass sur-face with silicone, and different intervals of sexual rest between semen collections. Results: A comparison of glassspheres 100, 200 and 390μm in diameter indicated that 200 μm spheres were optimal for selective filtration. Quantita-tive separation of live from dead sperm was demonstrated with a correlation between the percentage of motile sperm andretention of sperm by the filter of r = -0.87 (P < 0.05). Up to 0.02 mol/L NaFl did not alter the proportion ofsperm retained by the filter despite inhibiting sperm motility during filtration, an inhibition which was reversible. Pro-portions of live-dead sperm, based upon eosin staining, were unaffected by fluoride. Coating the glass spheres with sil-icone greatly reduced selective filtration. Dead sperm adherence to glass was reduced and resistance to NaFl inhibitionwas increased by daily ejaculation versus one-week intervals of sexual rest. Conclusion; These studies indicate thatthe adherence of sperm to glass is primarily due to some form of physico-chemical change accompanying death of thesperm cell independent of active sperm motility. This attraction between the sperm plasma membrane and glass is modi-fied by the age of the ejaculated sperm. This information is useful in evaluating different clinical procedures used forsperm separation. (Asian J Androl 2001 Sep; 3: 193-198)

关键词： sperm motility glass spere filters silicone fluorides inhibition