Uncovering regional characteristics from mobile phone data: A network science approach

We introduce network science methods to uncover inherent characteristics of functional regions. An aggregate spatial interaction network is constructed based on a large mobile phone data set including 431 million mobile calls made by 10 million anonymous customers over one month and the geographic locations of the mobile base towers involved in each call. We use Thiessen polygons (termed ‘cells’) as the unit of analysis to approximate the service area of each mobile base tower. Major findings encompass the following three aspects. First, cells with high betweenness centrality are linearly distributed in space, which closely aligns with major transportation corridors. We find that this pattern can be explained by analysing the characteristics of calling activities on transportation networks. Second, we detect a two‐level hierarchy of communities that correspond well to county and prefecture‐level administrative unit boundaries. Lastly, almost every community identified at the two hierarchical levels contains a cell with high betweenness. These cells are located near the political and economic centres and play the role of hubs in the regional socio‐economic system. This research demonstrates that networks built from mobile phone data provide new understandings of spatial interactions and regional structures.     

Poly(N-glycidyl carbazole): A new crosslinkable conjugated polymer

A poly(N-glycidyl carbazole) was synthesized by electropolymerization of 3,6-dibromo-N-glycidyl carbazole. Characterization of both products by different chemical and electrochemical techniques is then discussed. The polymer that showed electronic conductive properties when doped was crosslinked by cis-cyclohexane 1,2 dicarboxylic anhydride. The crosslinking reaction was followed by Fourier-transform infrared spectroscopy (FT-IR). An optimization of the crosslinking conditions was first performed on the monomer and subsequently applied to the polymer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1483–1492, 1999     

Effects of ingestion of a green seaweed,Ulva lactuca,upon caecal and colonic mucosas in the germ‐free rat and in the heteroxenic rat harbouring a human bacterial flora

Effect of ingestion of green seaweed, Ulva lactuca, (70 g kg⁻¹) during a 6‐week period on caecal and colonic mucosas was studied in germ‐free (GF) rats and in heteroxenic (HE) rats harbouring a human bacterial flora (GF rats associated with a human flora). The pH and sulphide concentration of the caecal contents, crypt morphometry, mitotic index and mucin types in the caecal and distal colonic mucosas were determined. In the GF caecum, Ulva strongly increased crypt depth and mucin‐containing cells irrespective of the mucin type studied (neutral, acidic or sulphated) compared to the control diet but had no significant effect on mitotic index. The crypt depth and mucin‐containing cells in the caecum were higher in HE than in GF control rats. They were slightly but significantly increased by Ulva. In the distal colon mucosa of GF rats, Ulva decreased crypt depth and cell number as well as sulphomucin‐containing cells. Conversely, in the HE rats, it increased crypt depth and reduced the number of neutral mucin‐containing cells. These results show that Ulva lactuca exerts an intrinsic effect on mucosal morphometry and on mucin biosynthesis in GF rats. No pathological alteration was observed in the mucosas and no significant modification of the mitotic index or sulphide production was observed in HE rats. © 1999 Society of Chemical Industry     

Skeletal Ryanodine Receptors Are Involved in Impaired Myogenic Differentiation in Duchenne Muscular Dystrophy Patients

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle wasting following repeated muscle damage and inadequate regeneration. Impaired myogenesis and differentiation play a major role in DMD as well as intracellular calcium (Ca²⁺) mishandling. Ca²⁺ release from the sarcoplasmic reticulum is mostly mediated by the type 1 ryanodine receptor (RYR1) that is required for skeletal muscle differentiation in animals. The study objective was to determine whether altered RYR1-mediated Ca²⁺ release contributes to myogenic differentiation impairment in DMD patients. The comparison of primary cultured myoblasts from six boys with DMD and five healthy controls highlighted delayed myoblast differentiation in DMD. Silencing RYR1 expression using specific si-RNA in a healthy control induced a similar delayed differentiation. In DMD myotubes, resting intracellular Ca²⁺ concentration was increased, but RYR1-mediated Ca²⁺ release was not changed compared with control myotubes. Incubation with the RYR-calstabin interaction stabilizer S107 decreased resting Ca²⁺ concentration in DMD myotubes to control values and improved calstabin1 binding to the RYR1 complex. S107 also improved myogenic differentiation in DMD. Furthermore, intracellular Ca²⁺ concentration was correlated with endomysial fibrosis, which is the only myopathologic parameter associated with poor motor outcome in patients with DMD. This suggested a potential relationship between RYR1 dysfunction and motor impairment. Our study highlights RYR1-mediated Ca²⁺ leakage in human DMD myotubes and its key role in myogenic differentiation impairment. RYR1 stabilization may be an interesting adjunctive therapeutic strategy in DMD.     

Building a global clock for observing computations in distributed memory parallel computers

A common time reference (i.e. global clock) is needed for observing the behavior of a distributed algorithm on a distributed computing system. The paper presents a pragmatic algorithm to build a global clock on any distributed system, which is optimal for homogeneous distributed memory parallel computers (DMPCs). In order to observe and sort concurrent events in common DMPCs, we need a global clock with a resolution finer than the message transfer time variance, which is better than what deterministic and fault-tolerant algorithms can obtain. Thus a statistical method is chosen as a building block to derive an original algorithm valid for any topology. Its main originality over related approaches is to cope with the problem of clock granularity in computing frequency offsets between local clocks to achieve a resolution comparable with the resolution of the physical clocks. This algorithm is particularly well suited for debugging distributed algorithms by means of trace recordings because after its acquisition step it does not induce message overhead: the perturbation induced on the execution remains as small as possible. It has been implemented on various DMPCs: Intel iPSC/2 hypercube and Paragon XP/S, Transputer-based networks and Sun networks, so we can provide some data about its behavior and performances on these DMPCs.     

Nonlinear isotropic constitutive laws: choice of the three invariants, convex potentials and constitutive inequalities

The aim of this paper is a new formulation of nonlinear isotropic constitutive laws. Our main hypothesis claims that the eigenvalues of stress and strain tensors are classified in the same order (the eigenvector associated to the highest eigenvalue of the stress tensor is also associated to the highest eigenvalue of the strain tensor, etc.). Further, we assume the existence of a differentiable convex isotropic potential. By introducing three new invariants for each tensor (called X, Y, Z for the stress tensor S and x, y, z for the strain tensor E) a constitutive law is revealed to be a simple duality between the chosen invariants: (x, y, z) and (X, Y, Z) look like Cartesian coordinates of E and S. We look at several potentials chosen as polynomials of these invariants. Finally, first and third order isotropic elasticity laws are reviewed and convexity of the potentials is discussed.     

Acousto-optically driven lensless single-shot ultrafast optical imaging

Driven by many applications in a wide span of scientific fields,a myriad of advanced ultrafast imaging techniques have emerged in the last decade,featuring reco...     

The role of activity restriction in poststroke depressive symptoms.

Objective: Little is known about the determinants of poststroke depression. The Activity Restriction Model of Depressed Affect (ARMDA) may be helpful in understanding poststroke depression but has never been tested in that context. The goal of this study was to examine the relation between activity restriction and depressive symptoms in stroke survivors during the period following discharge from the hospital. Method: Participants (N = 197) were assessed on three occasions: (1) time 1 (T1), 3 weeks following discharge; (2) time 2 (T2), 3 months after discharge; and (3) time 3 (T3), 6 months after discharge. Results: Although both stroke severity and activity restriction were significantly related to depressive symptoms, the relation between stroke severity and depression was no longer significant after controlling for activity restriction. Moreover, restrictions in daily activities and social roles were both related to depressive symptoms, but these relations were found to vary during the course of the period following discharge. Conclusions: These findings support the ARMDA and have practical implications for the prevention of poststroke depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)