Finite-time singularity in the dynamics of the world population, economic and financial indices

Contrary to common belief, both the Earth's human population and its economic output have grown faster than exponential, i.e., in a super-Malthusian mode, for most of the known history. These growth rates are compatible with a spontaneous singularity occuring at the same critical time 2052 +- 10 signaling an abrupt transition to a new regime. The degree of abruptness can be infered from the fact that the maximum of the world population growth rate was reached in 1970, i.e., about 80 years before the predicted singular time, corresponding to approximately 4% of the studied time interval over which the acceleration is documented. This rounding-off of the finite-time singularity is probably due to a combination of well-known finite-size effects and friction and suggests that we have already entered the transition region to a new regime. In theoretical support, a multivariate analysis coupling population, capital, R&D and technology shows that a dramatic acceleration in the population during most of the timespan can occur even though the isolated dynamics do not exhibit it. Possible scenarios for the cross-over and the new regime are discussed. Nottale, Chaline and Grou have recently independently applied a log-periodic analysis to the main crises of different civilisations. It is striking that these two independent analyses based on a different data set gives a critical time which is compatible within the error bars.Comment: 29 pages including 37 figures, addition of a Note Added in Proofs connecting with the independent analysis of Nottale, Chaline and Grou of economic crises and of the evolution of different civilisation

Conformation of a Polyelectrolyte Complexed to a Like-Charged Colloid

We report results from a molecular dynamics (MD) simulation on the conformations of a long flexible polyelectrolyte complexed to a charged sphere, \textit{both negatively charged}, in the presence of neutralizing counterions in the strong Coulomb coupling regime. The structure of this complex is very sensitive to the charge density of the polyelectrolyte. For a fully charged polyelectrolyte the polymer forms a dense two-dimensional "disk", whereas for a partially charged polyelectrolyte the monomers are spread over the colloidal surface. A mechanism involving the \textit{overcharging} of the polyelectrolyte by counterions is proposed to explain the observed conformations.Comment: 4 pages, 4 figures (6 EPS files

First Measurement of Collectivity of Coexisting Shapes based on Type II Shell Evolution: The Case of 96^{96}Zr

Background: Type II shell evolution has recently been identified as a microscopic cause for nuclear shape coexistence. Purpose: Establish a low-lying rotational band in 96-Zr. Methods: High-resolution inelastic electron scattering and a relative analysis of transition strengths are used. Results: The B(E2; 0_1^+ -> 2_2^+) value is measured and electromagnetic decay strengths of the secdond 2^+ state are deduced. Conclusions: Shape coexistence is established for 96-Zr. Type II shell evolution provides a systematic and quantitative mechanism to understand deformation at low excitation energies.Comment: 5 pages, 4 figure

Fluch oder Segen? – Zum Umgang mit Konflikten in Software-Implementierungsprozessen

Aus der EINLEITUNG: Nicht immer sind organisationale Veränderungsprozesse von Erfolg gekrönt – wie bei 1000 befragten Unternehmen die vergleichsweise hohe Quote von 38 % an Prozessen belegt, die als gescheitert betrachtet werden [18]. Als häufigste Ursache werden dabei „Widerstände der Mitarbeiter“ genannt. Auch die Implementierung einer neuen Technologie in einer Organisation stellt einen derartig verändernden Eingriff dar, dessen Gelingen nicht zuletzt auch an die Nutzung der neuen Technologie geknüpft ist [10]. Um diesem Ziel gerecht zu werden, existieren in der Informatik zahlreiche Ansätze, die Schnittstellen zwischen Mensch und Technik anwenderfreundlich zu gestalten. Dabei ist insbesondere die Akzeptanz der (neuen) Technologie seitens der Nutzer von zentraler Bedeutung [5]. Denn wenn sich beispielsweise bei der Einführung eines ERP-Systems zur integrierten IT-Portfolio-Planung die Mitarbeiter überwacht und kontrolliert fühlen und aus diesen Motiven heraus Vorwände und Ausreden finden, das System nicht zu nutzen, können sie die Implementierung massiv beeinträchtigen und verzögern, was sich in erhöhtem Aufwand und höheren Kosten niederschlägt. [...

Experimental observation of Aharonov-Bohm caging using orbital angular momentum modes in optical waveguides

The discovery of artificial gauge fields, controlling the dynamics of uncharged particles that otherwise elude the influence of standard electric or magnetic fields, has revolutionized the field of quantum simulation. Hence, developing new techniques to induce those fields is essential to boost quantum simulation in photonic structures. Here, we experimentally demonstrate in a photonic lattice the generation of an artificial gauge field by modifying the input state, overcoming the need to modify the geometry along the evolution or imposing the presence of external fields. In particular, we show that an effective magnetic flux naturally appears when light beams carrying orbital angular momentum are injected into waveguide lattices with certain configurations. To demonstrate the existence of that flux, we measure the resulting Aharonov-Bohm caging effect. Therefore, we prove the possibility of switching on and off artificial gauge fields by changing the topological charge of the input state, paving the way to access different topological regimes in one single structure, which represents an important step forward for optical quantum simulation

Spin fluctuations in the quasi-two dimensional Heisenberg ferromagnet GdI_2 studied by Electron Spin Resonance

The spin dynamics of GdI_2 have been investigated by ESR spectroscopy. The temperature dependences of the resonance field and ESR intensity are well described by the model for the spin susceptibility proposed by Eremin et al. [Phys. Rev. B 64, 064425 (2001)]. The temperature dependence of the resonance linewidth shows a maximum similar to the electrical resistance and is discussed in terms of scattering processes between conduction electrons and localized spins.Comment: to be published in PR

Optical properties and electronic structure of Ca-doped alpha'-NaV2O5

The dielectric function of alpha'-Na(1-x)Ca(x)V2O5 (0 < x < 20%) was measured for the a and b axes in the photon energy range 0.8-4.5 eV at room temperature. By varying the Ca-concentration we control the relative abundancy of V4+ and V5+. We observe that the intensity of the main optical absorption peak at 1 eV is proportional to the number of V5+ ions. This rules out the interpretation as a V4+ d-d excitation, and it establishes that this is the on-rung bonding-antibonding transition.Comment: 6 pages, ReVTeX, 5 figures in encapsulated postscript forma

A complex pattern of chemokine receptor expression is seen in osteosarcoma

<p>Abstract</p> <p>Background</p> <p>Osteosarcoma is the most frequent bone tumor in childhood and adolescence. Patients with primary metastatic disease have a poor prognosis. It is therefore important to better characterize the biology of this tumor to define new prognostic markers or therapeutic targets for tailored therapy. Chemokines and their receptors have been shown to be involved in the development and progression of malignant tumors. They are thought to be active participants in the biology of osteosarcoma. The function of specific chemokines and their receptors is strongly associated with the biological context and microenvironment of their expression. In this report we characterized the expression of a series of chemokine receptors in the complex environment that defines osteosarcoma.</p> <p>Methods</p> <p>The overall level of chemokine receptor mRNA expression was determined using TaqMan RT-PCR of microdissected archival patient biopsy samples. Expression was then verified at the protein level by immunohistochemistry using a series of receptor specific antibody reagents to elucidate the cellular association of expression.</p> <p>Results</p> <p>Expression at the RNA level was found for most of the tested receptors. CCR1 expression was found on infiltrating mononuclear and polynuclear giant cells in the tumor. Cells associated with the lining of intratumoral vessels were shown to express CCR4. Infiltrating mononuclear cells and tumor cells both showed expression of the receptor CCR5, while CCR7 was predominantly expressed by the mononuclear infiltrate. CCR10 was only very rarely detected in few scattered infiltrating cells.</p> <p>Conclusion</p> <p>Our data elucidate for the first time the cellular context of chemokine receptor expression in osteosarcoma. This is an important issue for better understanding potential chemokine/chemokine receptor function in the complex biologic processes that underlie the development and progression of osteosarcoma. Our data support the suggested involvement of chemokines and their receptors in diverse aspects of the biology of osteosarcoma, but also contradict aspects of previous reports describing the expression of these receptors in this tumor.</p