A place-focused model for social networks in cities

The focused organization theory of social ties proposes that the structure of human social networks can be arranged around extra-network foci, which can include shared physical spaces such as homes, workplaces, restaurants, and so on. Until now, this has been difficult to investigate on a large scale, but the huge volume of data available from online location-based social services now makes it possible to examine the friendships and mobility of many thousands of people, and to investigate the relationship between meetings at places and the structure of the social network. In this paper, we analyze a large dataset from Foursquare, the most popular online location-based social network. We examine the properties of city-based social networks, finding that they have common structural properties, and that the category of place where two people meet has very strong influence on the likelihood of their being friends. Inspired by these observations in combination with the focused organization theory, we then present a model to generate city-level social networks, and show that it produces networks with the structural properties seen in empirical data.Comment: 13 pages, 7 figures. IEEE/ASE SocialCom 201

Opportunistic Collaborative Beamforming with One-Bit Feedback

An energy-efficient opportunistic collaborative beamformer with one-bit feedback is proposed for ad hoc sensor networks over Rayleigh fading channels. In contrast to conventional collaborative beamforming schemes in which each source node uses channel state information to correct its local carrier offset and channel phase, the proposed beamforming scheme opportunistically selects a subset of source nodes whose received signals combine in a quasi-coherent manner at the intended receiver. No local phase-precompensation is performed by the nodes in the opportunistic collaborative beamformer. As a result, each node requires only one-bit of feedback from the destination in order to determine if it should or shouldn't participate in the collaborative beamformer. Theoretical analysis shows that the received signal power obtained with the proposed beamforming scheme scales linearly with the number of available source nodes. Since the the optimal node selection rule requires an exhaustive search over all possible subsets of source nodes, two low-complexity selection algorithms are developed. Simulation results confirm the effectiveness of opportunistic collaborative beamforming with the low-complexity selection algorithms.Comment: Proceedings of the Ninth IEEE Workshop on Signal Processing Advances in Wireless Communications, Recife, Brazil, July 6-9, 200

Tennessee tornado frequency, vulnerability, and relation to a large-scale climate variability

This work explores the climatologies of isolated tornadoes and tornado outbreaks across the state of Tennessee, a state that in some years experiences more tornadoes than states in the heart of Tornado Alley. Part one assesses tornado frequency characteristics and fatality statistics within 100 km of three major Tennessee cities (Nashville, Memphis, and Knoxville) between 1950 and 2013. Nashville reported the most tornadoes, (426) but Memphis reported the most fatalities. Knoxville and Nashville tornadoes occurred on fewer days, while Memphis tornadoes were spread across more tornado days. Spring was the most active season for tornadoes, but Memphis still experienced approximately 25% of its total tornadoes in the winter, a season prone to nocturnal tornadoes. There was no statistically significant difference between the seasonality of tornadoes for each of the cities, which is surprising given the longitudinal expanse of the state. Regional-scale analyses of this type provide insight on how tornado risk and vulnerability may vary considerably across a single state. Part two analyzes tornado outbreak characteristics (1980–2014) from a climatological perspective and assesses how a large-scale climate oscillation may affect tornado and tornado-outbreak frequencies across Tennessee. Results indicate that 72.5% of all tornadoes in Tennessee occur in outbreaks, when an outbreak is subjectively defined as any 24-hour period with four or more tornadoes within the state. Winter, defined as Dec/Jan/Feb, had the second-highest tornado-outbreak frequency. This provides a possible explanation for the high frequency of tornado-related fatalities in Tennessee, as the winter is a time of reduced daylight and is when nocturnal tornadoes, which are twice as likely to kill, are most prevalent. The Multivariate ENSO Index (MEI) was investigated using generalized linear models with a Quasi-Poisson distribution to determine if a relationship existed between tornado activity and a large-scale climate oscillation. Results indicate that above (below) average values of MEI, or El Niño (La Niña) events, are related to times of decreased (increased) tornado activity across Tennessee, and are supported by meteorological considerations. Offering future estimations of tornado activity on a seasonal or monthly scale can aid in reducing susceptibility to these dangerous events

Magnitude estimation of perceived distance over various distance ranges

Magnitude estimation judgments of perceived distance for stationary space vehicle under conditions simulating outer spac

A Consideration of the Nebraska Corporation Law in the Light of the American Bar Association’s Model Business Corporation Act

This article is presented as a general, rather than a technical, survey of the relationship between the Model Corporation Act and the present Nebraska Corporation Laws. The purpose is to give a brief comprehensive glance so that Nebraska attorneys will be able to more easily decide what their position will be on the proposed revamping of the present Nebraska Corporation Statutes. I. Introduction II. Definitions III. Substantive Provisions IV. Formation of Corporations V. Amendment VI. Merger and Consolidation VII. Sale of Assets VIII. Dissolution IX. Foreign Corporations X. Annual Reports XI. Fees, Franchise Taxes, and Charges XII. Penalties XIII. Miscellaneous Provisions XIV. Conclusion Appendi

A Consideration of the Nebraska Corporation Law in the Light of the American Bar Association’s Model Business Corporation Act

This article is presented as a general, rather than a technical, survey of the relationship between the Model Corporation Act and the present Nebraska Corporation Laws. The purpose is to give a brief comprehensive glance so that Nebraska attorneys will be able to more easily decide what their position will be on the proposed revamping of the present Nebraska Corporation Statutes. I. Introduction II. Definitions III. Substantive Provisions IV. Formation of Corporations V. Amendment VI. Merger and Consolidation VII. Sale of Assets VIII. Dissolution IX. Foreign Corporations X. Annual Reports XI. Fees, Franchise Taxes, and Charges XII. Penalties XIII. Miscellaneous Provisions XIV. Conclusion Appendi

Extensions of the siesta dft code for simulation of molecules

We describe extensions to the siesta density functional theory (dft) code [30], for the simulation of isolated molecules and their absorption spectra. The extensions allow for: - Use of a multi-grid solver for the Poisson equation on a finite dft mesh. Non-periodic, Dirichlet boundary conditions are computed by expansion of the electric multipoles over spherical harmonics. - Truncation of a molecular system by the method of design atom pseudo- potentials of Xiao and Zhang[32]. - Electrostatic potential fitting to determine effective atomic charges. - Derivation of electronic absorption transition energies and oscillator stren- gths from the raw spectra produced by a recently described, order O(N3), time-dependent dft code[21]. The code is furthermore integrated within siesta as a post-processing option

Methodological issues raised from the coverage survey of the MSF nutritional programme. Madarounfa and Guidan Roumdji, Maradi region, Niger 2006.

Abstract Poster - Congress: Surveying Health in Complex Situations; Brussels; June 2007