Mathematics and Morphogenesis of the City: A Geometrical Approach

Cities are living organisms. They are out of equilibrium, open systems that never stop developing and sometimes die. The local geography can be compared to a shell constraining its development. In brief, a city's current layout is a step in a running morphogenesis process. Thus cities display a huge diversity of shapes and none of traditional models from random graphs, complex networks theory or stochastic geometry takes into account geometrical, functional and dynamical aspects of a city in the same framework. We present here a global mathematical model dedicated to cities that permits describing, manipulating and explaining cities' overall shape and layout of their street systems. This street-based framework conciliates the topological and geometrical sides of the problem. From the static analysis of several French towns (topology of first and second order, anisotropy, streets scaling) we make the hypothesis that the development of a city follows a logic of division / extension of space. We propose a dynamical model that mimics this logic and which from simple general rules and a few parameters succeeds in generating a large diversity of cities and in reproducing the general features the static analysis has pointed out.Comment: 13 pages, 13 figure

Helicobacter pylori gamma-glutamyltranspeptidase upregulates COX-2 and EGF-related peptide expression in human gastric cells.

Gastric mucosa responds to Helicobacter pylori-induced cell damage by increasing the expression of COX-2 and EGF-related peptides. We sought to investigate the bacterial virulence factor/s and the host cellular pathways involved in the upregulation of COX-2, HB-EGF and amphiregulin in MKN 28 and AGS gastric mucosal cells. H. pylori strain CCUG 17874 was grown in Brucella broth supplemented with 0.2% (2,6-dimethyl)-beta-cyclodextrins. The soluble proteins released in the culture medium by the bacterium were fractionated by exclusion size and anion exchange chromatography. A single peak retaining the ability to upregulate COX-2 and HB-EGF mRNA and protein expression was obtained. SDS-PAGE analysis of the peak showed two peptides with an apparent molecular weight of 38 and 22 kDa, which were identified by automated Edman degradation analysis as the N-terminal and C-terminal peptides of H. pylori gamma-glutamyltranspeptidase respectively. Acivicin, a selective gamma-glutamyltranspeptidase inhibitor, counteracted H. pylori-induced upregulation of COX-2 and EGF-related peptide mRNA expression. An H. pylori isogenic mutant gamma-glutamyltranspeptidase-deficient strain did not exert any effect on COX-2, HB-EGF and amphiregulin mRNA expression. Blockade of phosphatidylinositol-3 kinase and p38 kinase, but not MAP kinase kinase, inhibited H. pylori gamma-glutamyltranspeptidase-induced upregulation of COX-2 and EGF-related peptide mRNA expression

Correlating pharmaceutical data with a national health survey as a proxy for estimating rural population health

Background: Chronic disease accounts for nearly three-quarters of US deaths, yet prevalence rates are not consistently reported at the state level and are not available at the sub-state level. This makes it difficult to assess trends in prevalence and impossible to measure sub-state differences. Such county-level differences could inform and direct the delivery of health services to those with the greatest need. Methods: We used a database of prescription drugs filled in the US as a proxy for nationwide, county-level prevalence of three top causes of death: heart disease, stroke, and diabetes. We tested whether prescription data are statistically valid proxy measures for prevalence, using the correlation between prescriptions filled at the state level and comparable Behavioral Risk Factor Surveillance System (BRFSS) data. We further tested for statistically significant national geographic patterns. Results: Fourteen correlations were tested for years in which the BRFSS questions were asked (1999-2003), and all were statistically significant. The correlations at the state level ranged from a low of 0.41 (stroke, 1999) to a high of 0.73 (heart disease, 2003). We also mapped self-reported chronic illnesses along with prescription rates associated with those illnesses. Conclusions: County prescription drug rates were shown to be valid measures of sub-state estimates of diagnosed prevalence and could be used to target health resources to counties in need. This methodology could be particularly helpful to rural areas whose prevalence rates cannot be estimated using national surveys. While there are no spatial statistically significant patterns nationally, there are significant variations within states that suggest unmet health needs

Some remarks on a model for rate-independent damage in thermo-visco-elastodynamics

This note deals with the analysis of a model for partial damage, where the rate- independent, unidirectional flow rule for the damage variable is coupled with the rate-dependent heat equation, and with the momentum balance featuring inertia and viscosity according to Kelvin-Voigt rheology. The results presented here combine the approach from Roubicek [1, 2] with the methods from Lazzaroni/Rossi/Thomas/Toader [3]. The present analysis encompasses, differently from [2], the monotonicity in time of damage and the dependence of the viscous tensor on damage and temperature, and, unlike [3], a nonconstant heat capacity and a time-dependent Dirichlet loading

In‐situ Bragg coherent X‐ray diffraction during tensile testing of an individual Au nanowire

Nanomechanical testing methods have drawn significant attention in both scientific and industrial research fields owing to unique deformation mechanisms in constrained volumes that underpin new property regimes. In-situ imaging equipment is now routinely employed to monitor the live evolution of material response during mechanical loading, with many of the testing developments tailored for electron microscopes (EMs). More recently, progress towards quantitative in-situ testing at synchrotron beamlines1–3 enabled by innovations in source brightness, focusing optics, and large size detectors has been made. Novel techniques such as Bragg coherent X-ray diffraction promise 3D information with phase information related to displacement fields (elastic strain, defects) within the material. However, despite the rich information that can be collected, many challenges arise in the realization of in-situ imaging of single nanostructures using such methods, including meticulous sample preparation and complex data analysis in retrieving phase information. In this work, we present the first successful systematic single nanowire tensile test while simultaneously recording 3D Bragg peaks using coherent X-rays. Defect free single crystalline \u3c110\u3e oriented Au nanowires were grown by physical vapor deposition4 and a 100 nm nanowire was harvested from the substrate and transferred to a nanotensile stage within a microelectromechanical system chip, which can be mounted to a coherent X-ray beamline. 3D Bragg peaks were recorded with nanofocused beam combined with 2D detector at each displacement step to discuss the evolution of strain and rotation of the nanowire during the tensile test. The movement of the peak sensitively depicted evolution of the deformation of the nanowire. In addition, the 3D Bragg coherent X-ray diffraction followed by phase retrieval has shown to reveal the internal strain state of nanostructure5 and this advanced technique is expected to reveal unique surface effects that mediate the overall mechanical performance of nano-scaled materials. 1. Cornelius, T. W. et al. In situ three-dimensional reciprocal-space mapping during mechanical deformation. J. Synchrotron Radiat. 19, 688–694 (2012). 2. Ren, Z. et al. Scanning force microscope for in situ nanofocused X-ray diffraction studies. J. Synchrotron Radiat. 21, 1128–1133 (2014). 3. Leclere, C. et al. In situ bending of an Au nanowire monitored by micro Laue diffraction. J. Appl. Crystallogr. 48, 291–296 (2015). 4. Richter, G. et al. Ultrahigh strength single crystalline nanowhiskers grown by physical vapor deposition. Nano Lett. 9, 3048–3052 (2009). 5. Haag, S. et al. Anomalous coherent diffraction of core-shell nano-objects: A methodology for determination of composition and strain fields. Phys. Rev. B 87, 35408 (2013)

Kinase and channel activity of TRPM6 are co-ordinated by a dimerization motif and pocket interaction

Contains fulltext : 138516.pdf (publisher's version ) (Open Access)Mutations in the gene that encodes the atypical channel-kinase TRPM6 (transient receptor potential melastatin 6) cause HSH (hypomagnesaemia with secondary hypocalcaemia), a disorder characterized by defective intestinal Mg2+ transport and impaired renal Mg2+ reabsorption. TRPM6, together with its homologue TRPM7, are unique proteins as they combine an ion channel domain with a C-terminally fused protein kinase domain. How TRPM6 channel and kinase activity are linked is unknown. Previous structural analysis revealed that TRPM7 possesses a non-catalytic dimerization motif preceding the kinase domain. This interacts with a dimerization pocket lying within the kinase domain. In the present study, we provide evidence that the dimerization motif in TRPM6 plays a critical role in regulating kinase activity as well as ion channel activity. We identify mutations within the TRPM6 dimerization motif (Leu1718 and Leu1721) or dimerization pocket (L1743A, Q1832K, A1836N, L1840A and L1919Q) that abolish dimerization and establish that these mutations inhibit protein kinase activity. We also demonstrate that kinase activity of a dimerization motif mutant can be restored by addition of a peptide encompassing the dimerization motif. Moreover, we observe that mutations that disrupt the dimerization motif and dimerization pocket interaction greatly diminish TRPM6 ion channel activity, in a manner that is independent of kinase activity. Finally, we analyse the impact on kinase activity of ten disease-causing missense mutations that lie outwith the protein kinase domain of TRPM6. This revealed that one mutation lying nearby the dimerization motif (S1754N), found previously to inhibit channel activity, abolished kinase activity. These results provide the first evidence that there is structural co-ordination between channel and kinase activity, which is mediated by the dimerization motif and pocket interaction. We discuss that modulation of this interaction could comprise a major regulatory mechanism by which TRPM6 function is controlled

Large bubble rupture sparks fast liquid jet

This Letter presents the novel experimental observation of long and narrow jets shooting out in disconnecting large elongated bubbles. We investigate this phenomenon by carrying out experiments with various viscosities, surface tensions, densities and nozzle radii. We propose a universal scaling law for the jet velocity, which unexpectedly involves the bubble height to the power 3/2. This anomalous exponent suggests an energy focusing phenomenon. We demonstrate experimentally that this focusing is purely gravity-driven and independent of the pinch-off singularity

Sensitivity and Insensitivity of Galaxy Cluster Surveys to New Physics

We study the implications and limitations of galaxy cluster surveys for constraining models of particle physics and gravity beyond the Standard Model. Flux limited cluster counts probe the history of large scale structure formation in the universe, and as such provide useful constraints on cosmological parameters. As a result of uncertainties in some aspects of cluster dynamics, cluster surveys are currently more useful for analyzing physics that would affect the formation of structure than physics that would modify the appearance of clusters. As an example we consider the Lambda-CDM cosmology and dimming mechanisms, such as photon-axion mixing.Comment: 24 pages, 8 eps figures. References added, discussion of scatter in relations between cluster observables lengthene