921 research outputs found
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An overview study of twitter in the UK local government
Copyright @ 2012 Brunel UniversityMicroblogging applications are becoming a momentous element of the public sector social media agenda. The potential of Twitter to update the public with frequent, concise and real-time content has motivated many pubic authorities to create their accounts, thus generating an interesting topic for research. This paper seeks to make an empirical and methodological contribution to this new body of knowledge by presenting an overview study of general Twitter accounts maintained by UK local government authorities. Over 296,000 tweets were collected from the 187officially listed local government accounts. The analysis was conducted in two stages: an examination of the Twitter networks developed by the accounts was followed by a structural analysis of the tweets. The combination of online research and social media analytics techniques enabled us to reach important conclusions about the use of Twitter by those authorities. The findings indicate high level of maturity of Twitter in the UK local government and point to several directions for further increasing the impact and visibility of those accounts within a social media strategy
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Twitter in local government: A study of Greater London authorities
Copyright @ 2011 SIG eGOVMicroblogging services are considered an emerging opportunity for authorities seeking to establish new communication channels with their public. Potential benefits evolve around enhancing transparency and interactivity, as well as sharing information regularly or during emergency events. The purpose of this exploratory study is to advance our empirical understanding of microblogging in local government. In particular, we reflect on online data collected to profile the use of Twitter by 29 Greater London local authorities (LAs). The study shows that London LAs have been accumulating significant experience with Twitter mainly over the past two years. In fact, many of them appear to incorporate conversational characteristics in their Tweets other than simply disseminating information. Furthermore, an analysis of Tweets during the August 2011 riots in England indicates the usefulness of the medium for responsibly informing the public and preventing rumours. Nevertheless, the study also identifies several points of improvement in the way public authorities are building their online networks; for example, in terms of connecting with each other and exploiting even more the conversational characteristics of Twitter
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Do social networking groups support online petitions?
This article is the post-print version of the final paper that has been accepted for publication and is forthcoming in Transforming Government: People, Process and Policy. Copyright @ Emerald Group Publishing LimitedEPetitioning has been emerging as arguably the most important eParticipation institutional activity. This paper aims to provide some insights into how ePetitions are perceived and supported by social networking sites. The connection between the UK government’s ePetitioning system and social networking groups linking to governmental petitions was investigated. Online data from Facebook were collected and analysed with respect to numbers of supporters compared to official signatures. The results indicate that although the process of signing an official petition is not more complex than joining a Facebook group, the membership of respective Facebook groups can be much higher. In particular, certain topics experienced very high support on Facebook which did not convert to signatures. The paper raises interesting questions about the potential uptake of citizen-government interactions in policy making mechanisms.The online research tool used for data collection in this paper was developed by Steven Sams who acknowledges support by the World Class University (WCU) program through the National Research Foundation of Korea. The program is funded by the Korean Ministry of Education, Science and Technology (No. 515-82-06574
An improved Monte Carlo method for direct calculation of the density of states
We present an efficient Monte Carlo algorithm for determining the density of
states which is based on the statistics of transition probabilities between
states. By measuring the infinite temperature transition probabilities--that
is, the probabilities associated with move proposal only--we are able to
extract excellent estimates of the density of states. When this estimator is
used in conjunction with a Wang-Landau sampling scheme [F. Wang and D. P.
Landau, Phys. Rev. Lett. 86, 2050 (2001)], we quickly achieve uniform sampling
of macrostates (e.g., energies) and systematically refine the calculated
density of states. This approach requires only potential energy evaluations,
continues to improve the statistical quality of its results as the simulation
time is extended, and is applicable to both lattice and continuum systems. We
test the algorithm on the Lennard-Jones liquid and demonstrate good statistical
convergence properties.Comment: 7 pages, 4 figures. to appear in Journal of Chemical Physic
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Stretching Method-Based Operational Modal Analysis of An Old Masonry Lighthouse.
We present in this paper a structural health monitoring study of the Egyptian lighthouse of Rethymnon in Crete, Greece. Using structural vibration data collected on a limited number of sensors during a 3-month period, we illustrate the potential of the stretching method for monitoring variations in the natural frequencies of the structure. The stretching method compares two signals, the current that refers to the actual state of the structure, with the reference one that characterizes the structure at a reference healthy condition. For the structure under study, an 8-day time interval is used for the reference quantity while the current quantity is computed using a time window of 24 h. Our results indicate that frequency shifts of 1% can be detected with high accuracy allowing for early damage assessment. We also provide a simple numerical model that is calibrated to match the natural frequencies estimated using the stretching method. The model is used to produce possible damage scenarios that correspond to 1% shift in the first natural frequencies. Although simple in nature, this model seems to deliver a realistic response of the structure. This is shown by comparing the response at the top of the structure to the actual measurement during a small earthquake. This is a preliminary study indicating the potential of the stretching method for structural health monitoring of historical monuments. The results are very promising. Further analysis is necessary requiring the deployment of the instrumentation (possibly with additional instruments) for a longer period of time
Optimized intermolecular potential for nitriles based on Anisotropic United Atoms model
An extension of the Anisotropic United Atoms intermolecular potential model is proposed for nitriles. The electrostatic part of the intermolecular potential is calculated using atomic charges obtained by a simple Mulliken population analysis. The repulsion-dispersion interaction parameters for methyl and methylene groups are taken from transferable AUA4 literature parameters [Ungerer et al., J. Chem. Phys., 2000, 112, 5499]. Non-bonding Lennard-Jones intermolecular potential parameters are regressed for the carbon and nitrogen atoms of the nitrile group (–C≡N) from experimental vapor-liquid equilibrium data of acetonitrile. Gibbs Ensemble Monte Carlo simulations and experimental data agreement is very good for acetonitrile, and better than previous molecular potential proposed by Hloucha et al. [J. Chem. Phys., 2000, 113, 5401]. The transferability of the resulting potential is then successfully tested, without any further readjustment, to predict vapor-liquid phase equilibrium of propionitrile and n-butyronitrile
On the Wang-Landau Method for Off-Lattice Simulations in the "Uniform" Ensemble
We present a rigorous derivation for off-lattice implementations of the
so-called "random-walk" algorithm recently introduced by Wang and Landau [PRL
86, 2050 (2001)]. Originally developed for discrete systems, the algorithm
samples configurations according to their inverse density of states using
Monte-Carlo moves; the estimate for the density of states is refined at each
simulation step and is ultimately used to calculate thermodynamic properties.
We present an implementation for atomic systems based on a rigorous separation
of kinetic and configurational contributions to the density of states. By
constructing a "uniform" ensemble for configurational degrees of freedom--in
which all potential energies, volumes, and numbers of particles are equally
probable--we establish a framework for the correct implementation of simulation
acceptance criteria and calculation of thermodynamic averages in the continuum
case. To demonstrate the generality of our approach, we perform sample
calculations for the Lennard-Jones fluid using two implementation variants and
in both cases find good agreement with established literature values for the
vapor-liquid coexistence locus.Comment: 21 pages, 4 figure
Crowding of Polymer Coils and Demixing in Nanoparticle-Polymer Mixtures
The Asakura-Oosawa-Vrij (AOV) model of colloid-polymer mixtures idealizes
nonadsorbing polymers as effective spheres that are fixed in size and
impenetrable to hard particles. Real polymer coils, however, are intrinsically
polydisperse in size (radius of gyration) and may be penetrated by smaller
particles. Crowding by nanoparticles can affect the size distribution of
polymer coils, thereby modifying effective depletion interactions and
thermodynamic stability. To analyse the influence of crowding on polymer
conformations and demixing phase behaviour, we adapt the AOV model to mixtures
of nanoparticles and ideal, penetrable polymer coils that can vary in size. We
perform Gibbs ensemble Monte Carlo simulations, including trial
nanoparticle-polymer overlaps and variations in radius of gyration. Results are
compared with predictions of free-volume theory. Simulation and theory
consistently predict that ideal polymers are compressed by nanoparticles and
that compressibility and penetrability stabilise nanoparticle-polymer mixtures.Comment: 18 pages, 4 figure
Thermodynamics of Electrolytes on Anisotropic Lattices
The phase behavior of ionic fluids on simple cubic and tetragonal
(anisotropic) lattices has been studied by grand canonical Monte Carlo
simulations. Systems with both the true lattice Coulombic potential and
continuous-space electrostatic interactions have been investigated. At
all degrees of anisotropy, only coexistence between a disordered low-density
phase and an ordered high-density phase with the structure similar to ionic
crystal was found, in contrast to recent theoretical predictions. Tricritical
parameters were determined to be monotonously increasing functions of
anisotropy parameters which is consistent with theoretical calculations based
on the Debye-H\"uckel approach. At large anisotropies a two-dimensional-like
behavior is observed, from which we estimated the dimensionless tricritical
temperature and density for the two-dimensional square lattice electrolyte to
be and .Comment: submitted to PR
Universality class of criticality in the restricted primitive model electrolyte
The 1:1 equisized hard-sphere electrolyte or restricted primitive model has
been simulated via grand-canonical fine-discretization Monte Carlo. Newly
devised unbiased finite-size extrapolation methods using temperature-density,
(T, rho), loci of inflections, Q = ^2/ maxima, canonical and C_V
criticality, yield estimates of (T_c, rho_c) to +- (0.04, 3)%. Extrapolated
exponents and Q-ratio are (gamma, nu, Q_c) = [1.24(3), 0.63(3); 0.624(2)] which
support Ising (n = 1) behavior with (1.23_9, 0.630_3; 0.623_6), but exclude
classical, XY (n = 2), SAW (n = 0), and n = 1 criticality with potentials
phi(r)>Phi/r^{4.9} when r \to \infty
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