Planar dynamics of a uniform beam with rigid bodies affixed to the ends

The planar dynamics of a uniform elastic beam subject to a variety of geometric and natural boundary conditions and external excitations were analyzed. The beams are inextensible and capable of small transverse bending deformations only. Classical beam vibration eigenvalue problems for a cantilever with tip mass, a cantilever with tip body and an unconstrained beam with rigid bodies at each are examined. The characteristic equations, eigenfunctions and orthogonality relations for each are derived. The forced vibration of a cantilever with tip body subject to base acceleration is analyzed. The exact solution of the governing nonhomogeneous partial differential equation with time dependent boundary conditions is presented and compared with a Rayleigh-Ritz approximate solution. The arbitrary planar motion of an elastic beam with rigid bodies at the ends is addressed. Equations of motion are derived for two modal expansions of the beam deflection. The motion equations are cast in a first order form suitable for numerical integration. Selected FORTRAN programs are provided

Transverse vibration and buckling of a cantilevered beam with tip body under constant axial base acceleration

The planar transverse bending behavior of a uniform cantilevered beam with rigid tip body subject to constant axial base acceleration was analyzed. The beam is inextensible and capable of small elastic transverse bending deformations only. Two classes of tip bodies are recognized: (1) mass centers located along the beam tip tangent line; and (2) mass centers with arbitrary offset towards the beam attachment point. The steady state response is studied for the beam end condition cases: free, tip mass, tip body with restricted mass center offset, and tip body with arbitrary mass center offset. The first three cases constitute classical Euler buckling problems, and the characteristic equation for the critical loads/accelerations are determined. For the last case a unique steady state solution exists. The free vibration response is examined for the two classes of tip body. The characteristic equation, eigenfunctions and their orthogonality properties are obtained for the case of restricted mass center offset. The vibration problem is nonhomogeneous for the case of arbitrary mass center offset. The exact solution is obtained as a sum of the steady state solution and a superposition of simple harmonic motions

The Emergence of El-Ni\~{n}o as an Autonomous Component in the Climate Network

We construct and analyze a climate network which represents the interdependent structure of the climate in different geographical zones and find that the network responds in a unique way to El-Ni\~{n}o events. Analyzing the dynamics of the climate network shows that when El-Ni\~{n}o events begin, the El-Ni\~{n}o basin partially loses its influence on its surroundings. After typically three months, this influence is restored while the basin loses almost all dependence on its surroundings and becomes \textit{autonomous}. The formation of an autonomous basin is the missing link to understand the seemingly contradicting phenomena of the afore--noticed weakening of the interdependencies in the climate network during El-Ni\~{n}o and the known impact of the anomalies inside the El-Ni\~{n}o basin on the global climate system.Comment: 5 pages,10 figure

Structure of the species-energy relationship

The relationship between energy availability and species richness (the species-energy relationship) is one of the best documented macroecological phenomena. However, the structure of species distribution along the gradient, the proximate driver of the relationship, is poorly known. Here, using data on the distribution of birds in southern Africa, for which species richness increases linearly with energy availability, we provide an explicit determination of this structure. We show that most species exhibit increasing occupancy towards more productive regions (occurring in more grid cells within a productivity class). However, average reporting rates per species within occupied grid cells, a correlate of local density, do not show a similar increase. The mean range of used energy levels and the mean geographical range size of species in southern Africa decreases along the energy gradient, as most species are present at high productivity levels but only some can extend their ranges towards lower levels. Species turnover among grid cells consequently decreases towards high energy levels. In summary, these patterns support the hypothesis that higher productivity leads to more species by increasing the probability of occurrence of resources that enable the persistence of viable populations, without necessarily affecting local population densities

Conjunto básico de marcadores de microsatélites identificados para el uso en estudios de genética de poblaciones en calamón común (Porphyrio porphyrio) en Java

Las poblaciones de calamón común han descendido en algunas partes del mundo debido a la degradación de los humedales y la caza furtiva. Los esfuerzos de conservación podrían beneficiarse de los estudios de genética de poblaciones que emplean marcadores de microsatélites. Aquí se describe la selección de los marcadores adecuados para tal estudio. Se han probado estos marcadores frente a la presencia de alelos nulos y desequilibrio gamético. De catorce loci candidatos, diez muestran una frecuencia de alelo nulo menor de 0,2 y no poseen desequilibrio de ligamiento significativo. Los loci seleccionados no presentaron desviación del equilibrio de Hardy–Weinberg (HWE) y tienen un contenido de información polimórfica (PIC) medio de 0,516. Sobre la base de esta prueba, se sugiere que estos loci deben ser incluidos en estudios de genética de poblaciones de esta especie.Populations of Purple Swamphen have been declining in some parts of the world due to wetland degradation and poaching. Conservation efforts might benefit from population genetic studies using microsatellite markers. Here we describe the selection of microsatellite markers suitable for such studies. We tested the markers against the evidence of the null alleles and gametic disequilibrium. From fourteen candidate loci, ten displayed a null alleles frequency of less than 0.2 and had no significant linkage disequilibrium. The selected loci showed no deviation from HWE and had a mean polymorphic information content of 0.516. Based on the test, we suggest these loci are suitable for population genetic studies of the species.Las poblaciones de calamón común han descendido en algunas partes del mundo debido a la degradación de los humedales y la caza furtiva. Los esfuerzos de conservación podrían beneficiarse de los estudios de genética de poblaciones que emplean marcadores de microsatélites. Aquí se describe la selección de los marcadores adecuados para tal estudio. Se han probado estos marcadores frente a la presencia de alelos nulos y desequilibrio gamético. De catorce loci candidatos, diez muestran una frecuencia de alelo nulo menor de 0,2 y no poseen desequilibrio de ligamiento significativo. Los loci seleccionados no presentaron desviación del equilibrio de Hardy–Weinberg (HWE) y tienen un contenido de información polimórfica (PIC) medio de 0,516. Sobre la base de esta prueba, se sugiere que estos loci deben ser incluidos en estudios de genética de poblaciones de esta especie

Towards the prediction of critical transitions in spatially extended populations with cubical homology

The prediction of critical transitions, such as extinction events, is vitally important to preserving vulnerable populations in the face of a rapidly changing climate and continuously increasing human resource usage. Predicting such events in spatially distributed populations is challenging because of the high dimensionality of the system and the complexity of the system dynamics. Here, we reduce the dimensionality of the problem by quantifying spatial patterns via Betti numbers ($\beta_0$ and $\beta_1$), which count particular topological features in a topological space. Spatial patterns representing regions occupied by the population are analyzed in a coupled patch population model with Ricker map growth and nearest-neighbors dispersal on a two-dimensional lattice. We illustrate how Betti numbers can be used to characterize spatial patterns by type, which in turn may be used to track spatiotemporal changes via Betti number time series and characterize asymptotic dynamics of the model parameter space. En route to a global extinction event, we find that the Betti number time series of a population exhibits characteristic changes. We hope these preliminary results will be used to aide in the prediction of critical transitions in spatially extended systems. Additional applications of this technique include analysis of spatial data (e.g., GIS) and model validation.Comment: Published in Contemporary Mathematics: Dynamical Systems and Random Processes, Volume 736, 201

The energetics response to a warmer climate: relative contributions from the transient and stationary eddies

We use the Lorenz Energy Cycle (LEC) to evaluate changes in global energetic activity due to CO<sub>2</sub>-doubling in the coupled atmosphere-ocean ECHAM5/MPI-OM model. Globally, the energetic activity – measured as the total conversion rate of available potential energy into kinetic energy – decreases by about 4 %. This weakening results from a dual response that consists of a strengthening of the LEC in the upper-troposphere and a weakening in the lower and middle troposphere. This is fully consistent with results from a coarser resolution version of the same coupled model. We further use our experiments to investigate the individual contributions of the transient and stationary eddy components to the main energetics response. <br><br> The transient eddy terms have a larger contribution to the total energetic activity than the stationary ones. We find that this is also true in terms of their 2 × CO<sub>2</sub>-response. Changes in the transient eddy components determine the main energetics response, whereas the stationary eddy components have very small contributions. Hence, the dual response – strengthening in the upper troposphere and weakening below – concerns mainly the transient eddy terms. We can relate qualitatively this response to the two main features of the 2 × CO<sub>2</sub> warming pattern: (a) the tropical upper-tropospheric warming increases the pole-to-equator temperature gradient – strengthening the energetic activity above – and enhances static stability – weakening the energetic activity below; and (b) the high-latitude surface warming decreases the pole-to-equator temperature gradient in the lower troposphere – weakening the energetic activity below. Despite the small contribution from the stationary eddies to the main energetics response, changes in stationary eddy available potential energy (<i>P</i><sub>se</sub>) reflect some features of the warming pattern: stronger land-sea contrasts at the subtropics and weaker land-sea contrasts at the high northern latitudes affect <i>P</i><sub>se</sub> regionally, but do not affect the global energetics response

Climate mode simulation of North Atlantic polar lows in a limited area model

Polar lows are not properly resolved in global re-analyses. In order to describe the year-to-year variability and decadal trends in the formation of such mesoscale storms, atmospheric limited area models, which post-process re-analysis data, may be an appropriate tool. In this study we demonstrate the merits and potential of this approach. A series of 3-week long ensemble simulations of weather situations over the NE Atlantic with a limited area model/regional climate model (CLM) are examined. The model was driven with NCEP-NCAR re-analyses at the lateral and lower boundaries. Additionally, the spectral nudging technique was used to enforce the large-scale circulation, as given by the NCEP-NCAR reanalysis, on the simulation. The ensemble members differ by initial conditions taken from several consecutive days. In most of the cases, a polar low developed after a simulated time of about 2 weeks, that is, long after the initialization of the model calculations. The spectrally nudged version of the model is very insensitive to initial conditions. The observed polar lows were reproduced in all ensemble members. A reasonable correlation between the simulated polar low features and those derived from a satellite product (HOAPS-III) and operational high-resolution weather analyses (DWD) is found. The polar lows are considerably deepened compared to the driving NCEP-NCAR analysis, but the comparison with weather maps indicates some differences in detail. When CLM is run without the large-scale constraint of spectral nudging, considerable variability emerges across the different ensemble members and the observed polar low often does not emerge. [References: 42

Gaussian capacity of the quantum bosonic channel with additive correlated Gaussian noise

We present an algorithm for calculation of the Gaussian classical capacity of a quantum bosonic memory channel with additive Gaussian noise. The algorithm, restricted to Gaussian input states, is applicable to all channels with noise correlations obeying certain conditions and works in the full input energy domain, beyond previous treatments of this problem. As an illustration, we study the optimal input states and capacity of a quantum memory channel with Gauss-Markov noise [J. Sch\"afer, Phys. Rev. A 80, 062313 (2009)]. We evaluate the enhancement of the transmission rate when using these optimal entangled input states by comparison with a product coherent-state encoding and find out that such a simple coherent-state encoding achieves not less than 90% of the capacity.Comment: 12+6 pages, 9 figures. Errors corrected, figures were made clearer, appendix improved and extende