The lifetime fitnesses of individuals comprising a population determine its numerical dynamics, and genetic variation in fitness results in evolutionary change. This dual importance of individual ...fitness is well understood, but empirical fitness records generally violate the assumptions of standard statistical approaches. This problem has undermined comprehensive study of fitness and impeded empirical synthesis of the numerical and genetic dynamics of populations. Recently developed aster models remedy this problem by explicitly modeling the dependence of later‐expressed components of fitness (e.g., fecundity) on those expressed earlier (e.g., survival to reproduce). Moreover, aster models employ different sampling distributions for different components of fitness (e.g., binomial for survival over a given interval and Poisson for fecundity). Analysis is done by maximum likelihood, and the resulting distributions for lifetime fitness closely approximate observed data. We illustrate the breadth of aster models' utility with three examples demonstrating estimation of the finite rate of increase, comparison of mean fitness among genotypic groups, and analysis of phenotypic selection. Aster models offer a unified approach to addressing the breadth of questions in evolution and ecology for which life‐history data are gathered.
Whispering-gallery modes are used for very accurate permittivity, dielectric loss, and temperature coefficient of permittivity measurements for both isotropic and uniaxially anisotropic dielectric ...materials. The relationship between resonant frequencies, dimensions of the resonant structure, and permittivity of the sample under test is calculated with a radial mode-matching technique. The relative accuracy of these computations is better then 10/sup -4/. The influence of conductor losses on dielectric loss tangent determination is treated for both whispering-gallery-mode and TE/sub 01/spl delta//-mode dielectric-resonator techniques. Two permittivity tensor components of sapphire and their temperature dependence were measured from 4.2 to 300 K. The total uncertainty in permittivity when use is made of whispering-gallery modes was estimated to be less than 0.05%. The uncertainty was limited principally by uncertainty in sample dimensions. Experimental and calculated resonant frequencies of several whispering-gallery modes differed by no more than 0.01%. The dielectric loss tangent of sapphire parallel and perpendicular to its anisotropy axis was calculated to be less than 10/sup -9/ at 4.2 K. The permittivity and dielectric loss tangent of a commercially available low-loss high-permittivity ceramic material has also been measured at S- and C-band frequencies using a large number of whispering-gallery modes.
Whispering gallery modes have been used for very accurate permittivity and dielectric loss measurements of ultralow loss isotropic and uniaxially anisotropic single crystals. Several materials, ...including sapphire, yttrium alumina garnet (YAG), quartz, and SrLaAlO\+v\4\-v\ were measured. The total absolute uncertainty in the real part of permittivity tensor components was estimated to be plus or minus 0.1%, limited principally by the uncertainty in sample dimensions. Imaginary parts of permittivities were measured with uncertainties of about 10%, limited by the accuracy of Q-factor measurements of whispering gallery modes. It has been observed that, for most crystals, dielectric losses can be approximated by a power function of absolute temperature only in limited temperature ranges. At temperatures between 4-50 K, losses are often affected by impurities which are always present in real crystals. (Original abstract)
1 Department of Neurology, University
Hospital Düsseldorf, 40225 Düsseldorf;
2 Department of Neurology, RWTH Aachen, 52072 Aachen; 3 Institute of Medicine, Research Center
Jülich, 52425 Jülich; ... 4 Department of
Anatomy and C. & O. Vogt Brain Research Institute,
Heinrich-Heine-University, 40225 Düsseldorf, Germany;
5 Institute of Human Physiology, University of
Parma, 43100 Parma, Italy; 6 Max-Planck-Institute
for Cognitive Neuroscience, 04103 Leipzig, Germany; and
7 Department of Mathematics, Kings College,
London WC2R 2LS, United Kingdom
Binkofski, F.,
G. R. Fink,
S. Geyer,
G. Buccino,
O. Gruber,
N. J. Shah,
J. G. Taylor,
R. J. Seitz,
K. Zilles, and
H.-J. Freund.
Neural Activity in Human Primary Motor Cortex Areas 4a and 4p Is
Modulated Differentially by Attention to Action. J. Neurophysiol. 88: 514-519, 2002. The mechanisms
underlying attention to action are poorly understood. Although
distracted by something else, we often maintain the accuracy of a
movement, which suggests that differential neural mechanisms for the
control of attended and nonattended action exist. Using functional
magnetic resonance imaging (fMRI) in normal volunteers and
probabilistic cytoarchitectonic maps, we observed that neural activity
in subarea 4p (posterior) within the primary motor cortex was modulated
by attention to action, while neural activity in subarea 4a (anterior)
was not. The data provide the direct evidence for differential neural
mechanisms during attended and unattended action in human primary motor cortex.
Measurements on low-loss materials using closed and open cavity resonators, and dielectric resonator methods are presented. Results indicate that consistent measurement results can be obtained with a ...number of well-characterized fixtures. Uncertainties associated with each method are addressed. Measurements also were performed on materials used in previous intercomparisons.
We present a new class of statistical models, designed for life history analysis of plants and animals, that allow joint analysis of data on survival and reproduction over multiple years, allow for ...variables having different probability distributions, and correctly account for the dependence of variables on earlier variables. We illustrate their utility with an analysis of data taken from an experimental study of Echinacea angustifolia sampled from remnant prairie populations in western Minnesota. These models generalize both generalized linear models and survival analysis. The joint distribution is factorized as a product of conditional distributions, each an exponential family with the conditioning variable being the sample size of the conditional distribution. The model may be heterogeneous, each conditional distribution being from a different exponential family. We show that the joint distribution is from a flat exponential family and derive its canonical parameters, Fisher information and other properties. These models are implemented in an R package 'aster' available from the Comprehensive R Archive Network, CRAN.
ABSTRACT We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of ...both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E−2.5 and E−2 power-law spectra with different energy cut-offs.
In this paper, different densities within a ceramic are used to provide a wide continuous range of dielectric constants for high-frequency applications. Cofiring different ceramic materials together ...to make a single unified structure to obtain different dielectric constant combinations is quite difficult due to phase stability issues and shrinkage mismatches. However, using various levels of porosity in order to alter the effective dielectric constant in the same material allows patterning different dielectric constants into a single unit. Since the structure is made from a single material, the varying porosity regions can be made compatible. Glassy-carbon-assisted and microcellular-structure-based porous titania allow for an extremely wide range of dielectric constants, ranging from 12 to 90, while maintaining a low loss tangent. Highly anisotropic materials are demonstrated herein to achieve a dielectric constant contrast of 90/9.6 using large-range aligned microcellular structure. Dielectric-resonator antennas are shown as an application of adjusting the bandwidth between 0.5% and 2.5% by tailoring the ceramic dielectric constant. A stratified-medium-loaded cavity resonator and a buried dielectric ring resonator internal to a microcellular substrate are used to demonstrate both the cofiring and variable dielectric constant capabilities of structured porosity.
The materials properties of undoped and low concentration Mg doped Ba
0.6Sr
0.4TiO
3 (BST) thin films are reported. The films were fabricated on single crystal (1
0
0) MgO and Pt coated Si substrates ...via the metalorganic solution deposition (MOSD) technique using carboxylate-alkoxide precursors and post-deposition annealed at 800 °C (film/MgO substrates) and 750 °C (film/Pt–Si substrates). The dielectric properties were measured at 10 GHz using unpatterned/non-metallized films via a tuned coupled/split dielectric resonator system and at 100 kHz using metal–insulator–metal capacitors. The structure, microstructure, surface morphology and film/substrate compositional quality were analyzed and correlated to the films dielectric and insulating properties. The Mg doped BST films exhibited improved dielectric loss and insulating characteristics compared to the undoped BST thin films. The improved dielectric properties, low leakage current, and good tunability of the low level Mg doped BST thin films merits strong potential for utilization in microwave tunable devices.
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