1,253 research outputs found

    Adjusting the tasseled cap brightness and greenness factors for atmospheric path radiance and absorption on a pixel by pixel basis

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    A radiative transfer model was used to convert ground measured reflectances into the radiance at the top of the atmosphere, for several levels of atmospheric path radiance. The radiance in MSS7 (0.8 to 1.1 m) was multiplied by the transmission fraction for atmospheres having different levels of precipitable water. The radiance values were converted to simulated LANDSAT digital counts for four path radiance levels and four levels of precipitable water. These values were used to calculate the Kauth-Thomas brightness, greenness, yellowness, and nonsuch factors. Brightness was affected by surface conditions and path radiance. Greenness was affected by surface conditions, path radiance, and precipitable water. Yellowness was affected by path radiance and nonsuch by precipitable water, and both factors changed only slightly with surface conditions. Yellowness and nonsuch were used to adjust brightness and greenness to produce factors that were affected only by surface conditions such as soils and vegetation, and not by path radiance and precipitable water

    Longitudinal dependence of the interplanetary perturbation produced by energetic type 4 solar flares and of the associated cosmic ray modulation

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    One of the most significant features of the flare-associated Forbush decreases (Fds) in the galatctic cosmic ray (c.r.) is the so-called East-West asymmetry: the solar flares (Sfs) observed in the Eastern or central region of the solar disk exhibit a higher probability to cause large Fds than the Sfs occurring in the Western portion of the disk. In particular the interplanetary perturbations generated by Type IV Sfs depress the c.r. intensity in a vast spiral cone-like region (modulated region) which extends along the interplanetary magnetic field from the neighborhood of the active region to the advancing perturbation, and that, immediately after the flare-generated perturbation, the maximum c.r. modulation is observed between 0 and 40 deg. W of the meridian plane crossings the flare site at time of flare (flare's meridian plane)

    Using multilayer network analysis to explore the temporal dynamics of collective behavior

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    This work was supported by the National Science Foundation IOS grant 1456010 and the National Institute of Health grant GM115509 to N.P.-W.Peer reviewedPublisher PD

    The use of multilayer network analysis in animal behaviour

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.We gratefully acknowledge the 806 supporters of MX16: the UC Davis Institute for Social Sciences, the U.S. Army Research Office 807 under Multidisciplinary University Research Initiative Award No. W911NF-13-1-0340, the UC 808 Davis Complexity Sciences Center, the UC Davis Anthropology Department, the UC Davis 809 Graduate Student Association, the UC Davis Department of Engineering, and the UC Davis 810 Office of Research.Network analysis has driven key developments in research on animal behaviour by providing quantitative methods to study the social structures of animal groups and populations. A recent formalism, known as multilayer network analysis, has advanced the study of multifaceted networked systems in many disciplines. It offers novel ways to study and quantify animal behaviour through connected ‘layers’ of interactions. In this article, we review common questions in animal behaviour that can be studied using a multilayer approach, and we link these questions to specific analyses. We outline the types of behavioural data and questions that may be suitable to study using multilayer network analysis. We detail several multilayer methods, which can provide new insights into questions about animal sociality at individual, group, population and evolutionary levels of organization. We give examples for how to implement multilayer methods to demonstrate how taking a multilayer approach can alter inferences about social structure and the positions of individuals within such a structure. Finally, we discuss caveats to undertaking multilayer network analysis in the study of animal social networks, and we call attention to methodological challenges for the application of these approaches. Our aim is to instigate the study of new questions about animal sociality using the new toolbox of multilayer network analysis.Natural Environment Research Council (NERC)National Science Foundation (NSF) Graduate Research FellowshipNFS IOS grantNIH R01NERC standard gran

    Resting Potential–dependent Regulation of the Voltage Sensitivity of Sodium Channel Gating in Rat Skeletal Muscle In Vivo

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    Normal muscle has a resting potential of −85 mV, but in a number of situations there is depolarization of the resting potential that alters excitability. To better understand the effect of resting potential on muscle excitability we attempted to accurately simulate excitability at both normal and depolarized resting potentials. To accurately simulate excitability we found that it was necessary to include a resting potential–dependent shift in the voltage dependence of sodium channel activation and fast inactivation. We recorded sodium currents from muscle fibers in vivo and found that prolonged changes in holding potential cause shifts in the voltage dependence of both activation and fast inactivation of sodium currents. We also found that altering the amplitude of the prepulse or test pulse produced differences in the voltage dependence of activation and inactivation respectively. Since only the Nav1.4 sodium channel isoform is present in significant quantity in adult skeletal muscle, this suggests that either there are multiple states of Nav1.4 that differ in their voltage dependence of gating or there is a distribution in the voltage dependence of gating of Nav1.4. Taken together, our data suggest that changes in resting potential toward more positive potentials favor states of Nav1.4 with depolarized voltage dependence of gating and thus shift voltage dependence of the sodium current. We propose that resting potential–induced shifts in the voltage dependence of sodium channel gating are essential to properly regulate muscle excitability in vivo

    Can multilayer networks advance animal behavior research?

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Interactions among individual animals — and between these individuals and their environment — yield complex, multifaceted systems. The development of multilayer network analysis offers a promising new approach for studying animal social behavior and relating it to eco-evolutionary dynamics

    Renormalization in Quantum Field Theory: An Improved Rigorous Method

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    The perturbative construction of the S-matrix in the causal spacetime approach of Epstein and Glaser may be interpreted as a method of regularization for divergent Feynman diagrams. The results of any method of regularization must be equivalent to those obtained from the Epstein-Glaser (EG) construction, within the freedom left by the latter. In particular, the conceptually well-defined approach of Bogoliubov, Parasuk, Hepp, and Zimmermann (BPHZ), though conceptually different from EG, meets this requirement. Based on this equivalence we propose a modified BPHZ procedure which provides a significant simplification of the techniques of perturbation theory, and which applies equally well to standard quantum field theory and to chiral theories. We illustrate the proposed method by a number of examples of various orders in perturbation theory. At the level of multi-loop diagrams we find that subdiagrams as classified by Zimmermann's forest formula in BPHZ may be restricted to subdiagrams in the sense of Epstein-Glaser, thus entailing an important reduction of actual computations. Furthermore, the relationship of our approach to the method of dimensional regularization is particularly transparent, without having to invoke analytic continuation to unphysical spacetime dimension, and sheds new light on certain parameters within dimensional regularization.Comment: 19 pages, 3 figure
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