552 research outputs found
Adoption of e-voting systems: A case study of Independent National Electoral Commission (INEC), Nigeria: A preliminary study
The trend in the technological development has
made the use of computer and its supporting
technologies mandatory in virtually all aspects of life.This is never an exception in the conventional voting process.Several issues have been revealed associated with the manual voting system which makes it inappropriate in the emerging technology-driven society. Several countries have successfully implemented an electronic voting technology. Considering Nigeria as a developing nation with quite a number of constraints regarding technological
innovations, there is therefore the need to
investigate the readiness on the part of the
organization empowered to conduct elections in
the country (INEC) so as to pave ways for its
successful implementation.In this paper, the
relationship among the variables of adoption
evidenced from the previous literature was
investigated using correlation coefficients and multiple linear regressions.As a pilot study, only 47 responses were captured from senior staffs of INEC. The results show that there is strong relationship between the variables examined
Slowly rotating black holes in the Horava-Lifshitz gravity
We investigate slowly rotating black holes in the Ho\v{r}ava-Lifshitz (HL)
gravity. For and , we find a slowly rotating black
hole of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. We
discuss their thermodynamic properties by computing mass, temperature, angular
momentum, and angular velocity on the horizon.Comment: 12 pages, no figures, version to appear in EPJ
Approximation Algorithms for the Capacitated Domination Problem
We consider the {\em Capacitated Domination} problem, which models a
service-requirement assignment scenario and is also a generalization of the
well-known {\em Dominating Set} problem. In this problem, given a graph with
three parameters defined on each vertex, namely cost, capacity, and demand, we
want to find an assignment of demands to vertices of least cost such that the
demand of each vertex is satisfied subject to the capacity constraint of each
vertex providing the service. In terms of polynomial time approximations, we
present logarithmic approximation algorithms with respect to different demand
assignment models for this problem on general graphs, which also establishes
the corresponding approximation results to the well-known approximations of the
traditional {\em Dominating Set} problem. Together with our previous work, this
closes the problem of generally approximating the optimal solution. On the
other hand, from the perspective of parameterization, we prove that this
problem is {\it W[1]}-hard when parameterized by a structure of the graph
called treewidth. Based on this hardness result, we present exact
fixed-parameter tractable algorithms when parameterized by treewidth and
maximum capacity of the vertices. This algorithm is further extended to obtain
pseudo-polynomial time approximation schemes for planar graphs
Extremal black holes in the Ho\v{r}ava-Lifshitz gravity
We study the near-horizon geometry of extremal black holes in the
Ho\v{r}ava-Lifshitz gravity with a flow parameter . For ,
near-horizon geometry of extremal black holes are AdS with
different radii, depending on the (modified) Ho\v{r}ava-Lifshitz gravity. For
, the radius of is negative, which means
that the near-horizon geometry is ill-defined and the corresponding
Bekenstein-Hawking entropy is zero. We show explicitly that the entropy
function approach does not work for obtaining the Bekenstein-Hawking entropy of
extremal black holes.Comment: 18 pages, v2:some points on Lifshitz black holes claified, v3:
version to appear in EJP
Quasinormal modes and hidden conformal symmetry in the Reissner-Nordstrom black hole
It is shown that the scalar wave equation in the near-horizon limit respects
a hidden SL(2,R) invariance in the Reissner-Nordstrom (RN) black hole
spacetimes. We use the SL(2,R) symmetry to determine algebraically the purely
imaginary quasinormal frequencies of the RN black hole. We confirm that these
are exactly quasinormal modes of scalar perturbation around the near-extremal
black hole.Comment: 17 pages, 1 figure, version to appear in EPJ
Dilaton gravity approach to three dimensional Lifshitz black hole
The z=3 Lifshitz black hole is an exact black hole solution to the new
massive gravity in three dimensions. In order to understand this black hole
clearly, we perform a dimensional reduction to two dimensional dilaton gravity
by utilizing the circular symmetry. Considering the linear dilaton, we find the
same Lifshitz black hole in two dimensions. This implies that all thermodynamic
quantities of the z=3 Lifshitz black hole could be obtained from its
corresponding black hole in two dimensions. As a result, we derive the
temperature, mass, heat capacity, Bekesnstein-Hawking entropy, and free energy.Comment: 13 pages, 1 figure, version to appear in EPJ
Thermodynamics of Ho\v{r}ava-Lifshitz black holes
We study black holes in the Ho\v{r}ava-Lifshitz gravity with a parameter
. For , the black holes behave the Lifshitz black
holes with dynamical exponent , the black
holes behave the Reissner-Nordstr\"om type black hole in asymptotically flat
spacetimes. Hence, these all are quite different from the Schwarzschild-AdS
black hole of Einstein gravity. The temperature, mass, entropy, and heat
capacity are derived for investigating thermodynamic properties of these black
holes.Comment: 12 pages, 5 figures, v2:substantial improved version to make
connection to Lifshitz black holes and Reissner-Norstr\"om type black
holes,v3: version to appear in EPJ
Far-infrared photo-conductivity of electrons in an array of nano-structured antidots
We present far-infrared (FIR) photo-conductivity measurements for a
two-dimensional electron gas in an array of nano-structured antidots. We
detect, resistively and spectrally resolved, both the magnetoplasmon and the
edge-magnetoplasmon modes. Temperature-dependent measurements demonstrates that
both modes contribute to the photo resistance by heating the electron gas via
resonant absorption of the FIR radiation. Influences of spin effect and phonon
bands on the collective excitations in the antidot lattice are observed.Comment: 5 pages, 3 figure
Incision history of the Black Canyon of Gunnison, Colorado, over the past ~1 Ma inferred from dating of fluvial gravel deposits
Spatio-temporal variability in fluvial incision rates in bedrock channels provides data regarding uplift and denudation histories of landscapes. The longitudinal profi le of the Gunnison River (Colorado), tributary to the Colorado River, contains a prominent knickzone with 800 m of relief across it within the Black Canyon of the Gunnison. Average bedrock incision rates over the last 0.64 Ma surrounding the knickpoint vary from 150 m/Ma (downstream) to 400-550 m/Ma (within) to 90-95 m/Ma (upstream), suggesting it is a transient feature. Lava Creek B ash constrains strath terraces along a paleoprofi le of the river. An isochron cosmogenic burial date in the paleo-Bostwick River of 870 ± 220 ka is consistent with the presence of 0.64 Ma Lava Creek B ash in locally derived, stratigraphically younger sediment. With 350 m of incision since deposition, we determine an incision rate of 400-550 m/Ma, reflecting incision through resistant basement rock at 2-3 times regional incision rates. Such contrast is attributed to a wave of transient incision, potentially initiated by downstream base-level fall during abandonment of Unaweep Canyon at ca. 1 Ma. Rate extrapolation indicates that the ~700 m depth of Black Canyon has been eroded since 1.3-1.75 Ma. The Black Canyon knickpoint overlies a strong gradient between low-velocity mantle under the Colorado Rockies and higher-velocity mantle of the Colorado Plateau. We interpret recent reorganization and transient incision of both the Gunnison River and upper Colorado River systems to be a response to mantle-driven epeirogenic uplift of the southern Rockies in the last 10 Ma
Exchange anisotropy, disorder and frustration in diluted, predominantly ferromagnetic, Heisenberg spin systems
Motivated by the recent suggestion of anisotropic effective exchange
interactions between Mn spins in GaMnAs (arising as a result of
spin-orbit coupling), we study their effects in diluted Heisenberg spin
systems. We perform Monte Carlo simulations on several phenomenological model
spin Hamiltonians, and investigate the extent to which frustration induced by
anisotropic exchanges can reduce the low temperature magnetization in these
models and the interplay of this effect with disorder in the exchange. In a
model with low coordination number and purely ferromagnetic (FM) exchanges, we
find that the low temperature magnetization is gradually reduced as exchange
anisotropy is turned on. However, as the connectivity of the model is
increased, the effect of small-to-moderate anisotropy is suppressed, and the
magnetization regains its maximum saturation value at low temperatures unless
the distribution of exchanges is very wide. To obtain significant suppression
of the low temperature magnetization in a model with high connectivity, as is
found for long-range interactions, we find it necessary to have both
ferromagnetic and antiferromagnetic (AFM) exchanges (e.g. as in the RKKY
interaction). This implies that disorder in the sign of the exchange
interaction is much more effective in suppressing magnetization at low
temperatures than exchange anisotropy.Comment: 9 pages, 8 figure
- …