On the heterogeneous character of water's amorphous polymorphism

In this letter we report {\it in situ} small--angle neutron scattering results on the high--density (HDA) and low-density amorphous (LDA) ice structures and on intermediate structures as found during the temperature induced transformation of HDA into LDA. We show that the small--angle signal is characterised by two $Q$ regimes featuring different properties ($Q$ is the modulus of the scattering vector defined as $Q = 4\pi\sin{(\Theta)}/\lambda_{\rm i}$ with $\Theta$ being half the scattering angle and $\lambda_{\rm i}$ the incident neutron wavelength). The very low--$Q$ regime ($< 5\times 10^{-2}$ \AA $^{-1}$) is dominated by a Porod--limit scattering. Its intensity reduces in the course of the HDA to LDA transformation following a kinetics reminiscent of that observed in wide--angle diffraction experiments. The small--angle neutron scattering formfactor in the intermediate regime of $5 \times 10^{-2} < Q < 0.5$ \AA$^{-1}$ HDA and LDA features a rather flat plateau. However, the HDA signal shows an ascending intensity towards smaller $Q$ marking this amorphous structure as heterogeneous. When following the HDA to LDA transition the formfactor shows a pronounced transient excess in intensity marking all intermediate structures as strongly heterogeneous on a length scale of some nano--meters

Species Abundance Patterns in Complex Evolutionary Dynamics

An analytic theory of species abundance patterns (SAPs) in biological networks is presented. The theory is based on multispecies replicator dynamics equivalent to the Lotka-Volterra equation, with diverse interspecies interactions. Various SAPs observed in nature are derived from a single parameter. The abundance distribution is formed like a widely observed left-skewed lognormal distribution. As the model has a general form, the result can be applied to similar patterns in other complex biological networks, e.g. gene expression.Comment: 4 pages, 3 figures. Physical Review Letters, in pres

Epidemic threshold in structured scale-free networks

We analyze the spreading of viruses in scale-free networks with high clustering and degree correlations, as found in the Internet graph. For the Suscetible-Infected-Susceptible model of epidemics the prevalence undergoes a phase transition at a finite threshold of the transmission probability. Comparing with the absence of a finite threshold in networks with purely random wiring, our result suggests that high clustering and degree correlations protect scale-free networks against the spreading of viruses. We introduce and verify a quantitative description of the epidemic threshold based on the connectivity of the neighborhoods of the hubs.Comment: 4 pages, 4 figure

Instability of spatial patterns and its ambiguous impact on species diversity

Self-arrangement of individuals into spatial patterns often accompanies and promotes species diversity in ecological systems. Here, we investigate pattern formation arising from cyclic dominance of three species, operating near a bifurcation point. In its vicinity, an Eckhaus instability occurs, leading to convectively unstable "blurred" patterns. At the bifurcation point, stochastic effects dominate and induce counterintuitive effects on diversity: Large patterns, emerging for medium values of individuals' mobility, lead to rapid species extinction, while small patterns (low mobility) promote diversity, and high mobilities render spatial structures irrelevant. We provide a quantitative analysis of these phenomena, employing a complex Ginzburg-Landau equation.Comment: 4 pages, 3 figures and supplementary information. To appear in Phys. Rev. Lett

Eigenvalue Separation in Some Random Matrix Models

The eigenvalue density for members of the Gaussian orthogonal and unitary ensembles follows the Wigner semi-circle law. If the Gaussian entries are all shifted by a constant amount c/Sqrt(2N), where N is the size of the matrix, in the large N limit a single eigenvalue will separate from the support of the Wigner semi-circle provided c > 1. In this study, using an asymptotic analysis of the secular equation for the eigenvalue condition, we compare this effect to analogous effects occurring in general variance Wishart matrices and matrices from the shifted mean chiral ensemble. We undertake an analogous comparative study of eigenvalue separation properties when the size of the matrices are fixed and c goes to infinity, and higher rank analogues of this setting. This is done using exact expressions for eigenvalue probability densities in terms of generalized hypergeometric functions, and using the interpretation of the latter as a Green function in the Dyson Brownian motion model. For the shifted mean Gaussian unitary ensemble and its analogues an alternative approach is to use exact expressions for the correlation functions in terms of classical orthogonal polynomials and associated multiple generalizations. By using these exact expressions to compute and plot the eigenvalue density, illustrations of the various eigenvalue separation effects are obtained.Comment: 25 pages, 9 figures include

Heteroclinic Chaos, Chaotic Itinerancy and Neutral Attractors in Symmetrical Replicator Equations with Mutations

A replicator equation with mutation processes is numerically studied. Without any mutations, two characteristics of the replicator dynamics are known: an exponential divergence of the dominance period, and hierarchical orderings of the attractors. A mutation introduces some new aspects: the emergence of structurally stable attractors, and chaotic itinerant behavior. In addition, it is reported that a neutral attractor can exist in the mutataion rate -> +0 region.Comment: 4 pages, 9 figure

The impact of the populace on government of the city of Rome in the fourth century A.D

The purpose of this study is to show how popular rioting and fear of popular rioting and unrest came to be such a major concern of the Prefect of the City and his subordinates during the fourth century, a period when Emperors no longer lived at Rome (and so did net have to fear for their personal safety, when Plebeians were rioting in Rome), and in the early years of which the Praetorian Guard, the only force in Rome capable of crushing popular riots by brute force, was disbanded. The first chapter deals with the status of Rome in the fourth century. It was no longer the political centre of the Empire, but it seems to have been the centre of patriotic feeling more than ever before, which is perhaps why Emperors were less harsh to the plebeians when they rioted than to provincials, and is why they took pains to help the Prefect of the City in dealing with plebeian grievances. Chapter 2 deals with the discomforts of living in Rome, and subsisting there on the one hand, and the compensations, the bread and circuses, on the other. The third chapter deals with the causes of disturbances at Rome, and how typical of the metropolises of the Empire (Rome, Alexandria, Antioch, Carthage and Constantinople) were the causes of riots, and their level of violence. Fourth century Rome is also compared to Rome in the Severan period to see how much or little it had changed. Chapter 4 concerns the short term solutions to disturbances that is the immediate options available to and adopted by the authorities once the disturbance had started. Chapter 5 deals with the laws passed by Emperors to ensure that the people got their bread and circuses, and with other areas in which Emperors concerned themselves, such as the provision of a rudimentary health service

Kontestasi Pemikiran Dasar Negara dalam Perwujudan Hukum di Indonesia

Pembentukan dasar negara menempati proses penting dalam sejarah kebangsaan.Dari sinilah kita dapat melihat negara ini mau dibawa ke mana oleh founding fathers. Saatmenilik proses kesejarahan panjang itu, tergambar bahwa kontestasi pemikiran pembentukandasar negara tidaklah sederhana. Para tokoh mencoba merebut simpati dan adu gagasan.“Pertaruangan” ide dan gagasan inilah yang menjadikan produk pemikiran dasar negarasenantisa dinamis hingga saat ini. Apalagi dalam perbincangan negara berdasar Pancasilaatau berdasarkan Islam. Peran tokoh nasionalis Islam sangat penting dalam Perumusan dasarnegara Indonesia. Terutama pada penghapusan kata-kata yang kurang berkenan pada butirpertama Piagam Jakarta, hal ini tidak lantas dipandang sebagai suatu kekalahan politik umatIslam. Sebaliknya hal ini harus dipandang sebagai sebuah sikap inklusif umat Islam yanghendak dikembangkan demi mewujudkan prinsip Islam sebagai suatu ajaran yang lebihmementingkan kemaslahatan bersama

Secondary literacy across the curriculum: Challenges and possibilities

This paper discusses the challenges and possibilities attendant upon successfully implementing literacy across the curriculum initiatives – or ‘school language policies’ as they have come to be known - particularly at the secondary or high school level. It provides a theoretical background to these issues, exploring previous academic discussions of school language policies, and highlights key areas of concern as well as opportunity with respect to school implementation of such policies. As such, it provides a necessary conceptual background to the subsequent papers in this special issue, which focus upon the Secondary Schools’ Literacy Initiative (SSLI) – a New Zealand funded programme that aims to establish cross-curricular language and literacy policies in secondary schools