9,533 research outputs found
Investigation of the AODV and the SDWCA QoS handling at different utilisation levels in adaptive clustering environments
A simulation study using NS2 simulator using two main routing protocols with specific design parameters has been carried out to investigate the QoS main parameters such as throughput, delay, Jitter, Control Overhead, Number of packets, number of packets dropped and the rating overheads. The traffic is made of CBR slow video traffic. From the result it is noted that the SDWCA routing protocol outperforms the AODV routing protocols in the throughput, the delay and the jitter issues at different loading levels
Generalized Mittag-Leffler Distributions and Processes for Applications in Astrophysics and Time Series Modeling
Geometric generalized Mittag-Leffler distributions having the Laplace
transform is
introduced and its properties are discussed. Autoregressive processes with
Mittag-Leffler and geometric generalized Mittag-Leffler marginal distributions
are developed. Haubold and Mathai (2000) derived a closed form representation
of the fractional kinetic equation and thermonuclear function in terms of
Mittag-Leffler function. Saxena et al (2002, 2004a,b) extended the result and
derived the solutions of a number of fractional kinetic equations in terms of
generalized Mittag-Leffler functions. These results are useful in explaining
various fundamental laws of physics. Here we develop first-order autoregressive
time series models and the properties are explored. The results have
applications in various areas like astrophysics, space sciences, meteorology,
financial modeling and reliability modeling.Comment: 12 pages, LaTe
The effect of cigarette price increase on the cigarette consumption in Taiwan: evidence from the National Health Interview Surveys on cigarette consumption
BACKGROUND: This study uses cigarette price elasticity to evaluate the effect of a new excise tax increase on cigarette consumption and to investigate responses from various types of smokers. METHODS: Our sample consisted of current smokers between 17 and 69 years old interviewed during an annual face-to-face survey conducted by Taiwan National Health Research Institutes between 2000 to 2003. We used Ordinary Least Squares (OLS) procedure to estimate double logarithmic function of cigarette demand and cigarette price elasticity. RESULTS: In 2002, after Taiwan had enacted the new tax scheme, cigarette price elasticity in Taiwan was found to be -0.5274. The new tax scheme brought about an average annual 13.27 packs/person (10.5%) reduction in cigarette consumption. Using the cigarette price elasticity estimate from -0.309 in 2003, we calculated that if the Health and Welfare Tax were increased by another NT$ 3 per pack and cigarette producers shifted this increase to the consumers, cigarette consumption would be reduced by 2.47 packs/person (2.2%). The value of the estimated cigarette price elasticity is smaller than one, meaning that the tax will not only reduce cigarette consumption but it will also generate additional tax revenues. Male smokers who had no income or who smoked light cigarettes were found to be more responsive to changes in cigarette price. CONCLUSIONS: An additional tax added to the cost of cigarettes would bring about a reduction in cigarette consumption and increased tax revenues. It would also help reduce incidents smoking-related illnesses. The additional tax revenues generated by the tax increase could be used to offset the current financial deficiency of Taiwan's National Health Insurance program and provide better public services
Phylogeny of Prokaryotes and Chloroplasts Revealed by a Simple Composition Approach on All Protein Sequences from Complete Genomes Without Sequence Alignment
The complete genomes of living organisms have provided much information on their phylogenetic relationships. Similarly, the complete genomes of chloroplasts have helped to resolve the evolution of this organelle in photosynthetic eukaryotes. In this paper we propose an alternative method of phylogenetic analysis using compositional statistics for all protein sequences from complete genomes. This new method is conceptually simpler than and computationally as fast as the one proposed by Qi et al. (2004b) and Chu et al. (2004). The same data sets used in Qi et al. (2004b) and Chu et al. (2004) are analyzed using the new method. Our distance-based phylogenic tree of the 109 prokaryotes and eukaryotes agrees with the biologists tree of life based on 16S rRNA comparison in a predominant majority of basic branching and most lower taxa. Our phylogenetic analysis also shows that the chloroplast genomes are separated to two major clades corresponding to chlorophytes s.l. and rhodophytes s.l. The interrelationships among the chloroplasts are largely in agreement with the current understanding on chloroplast evolution
SMART: Unique splitting-while-merging framework for gene clustering
Copyright @ 2014 Fa et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.Successful clustering algorithms are highly dependent on parameter settings. The clustering performance degrades significantly unless parameters are properly set, and yet, it is difficult to set these parameters a priori. To address this issue, in this paper, we propose a unique splitting-while-merging clustering framework, named “splitting merging awareness tactics” (SMART), which does not require any a priori knowledge of either the number of clusters or even the possible range of this number. Unlike existing self-splitting algorithms, which over-cluster the dataset to a large number of clusters and then merge some similar clusters, our framework has the ability to split and merge clusters automatically during the process and produces the the most reliable clustering results, by intrinsically integrating many clustering techniques and tasks. The SMART framework is implemented with two distinct clustering paradigms in two algorithms: competitive learning and finite mixture model. Nevertheless, within the proposed SMART framework, many other algorithms can be derived for different clustering paradigms. The minimum message length algorithm is integrated into the framework as the clustering selection criterion. The usefulness of the SMART framework and its algorithms is tested in demonstration datasets and simulated gene expression datasets. Moreover, two real microarray gene expression datasets are studied using this approach. Based on the performance of many metrics, all numerical results show that SMART is superior to compared existing self-splitting algorithms and traditional algorithms. Three main properties of the proposed SMART framework are summarized as: (1) needing no parameters dependent on the respective dataset or a priori knowledge about the datasets, (2) extendible to many different applications, (3) offering superior performance compared with counterpart algorithms.National Institute for Health Researc
Emergent quantum confinement at topological insulator surfaces
Bismuth-chalchogenides are model examples of three-dimensional topological
insulators. Their ideal bulk-truncated surface hosts a single spin-helical
surface state, which is the simplest possible surface electronic structure
allowed by their non-trivial topology. They are therefore widely
regarded ideal templates to realize the predicted exotic phenomena and
applications of this topological surface state. However, real surfaces of such
compounds, even if kept in ultra-high vacuum, rapidly develop a much more
complex electronic structure whose origin and properties have proved
controversial. Here, we demonstrate that a conceptually simple model,
implementing a semiconductor-like band bending in a parameter-free
tight-binding supercell calculation, can quantitatively explain the entire
measured hierarchy of electronic states. In combination with circular dichroism
in angle-resolved photoemission (ARPES) experiments, we further uncover a rich
three-dimensional spin texture of this surface electronic system, resulting
from the non-trivial topology of the bulk band structure. Moreover, our study
reveals how the full surface-bulk connectivity in topological insulators is
modified by quantum confinement.Comment: 9 pages, including supplementary information, 4+4 figures. A high
resolution version is available at
http://www.st-andrews.ac.uk/~pdk6/pub_files/TI_quant_conf_high_res.pd
Inspiratory muscle warm-up does not improve cycling time-trial performance
Purpose: This study examined the effects of an active cycling warm-up, with and without the addition of an inspiratory muscle warm-up (IMW), on 10-km cycling time-trial performance
Exoplanets and SETI
The discovery of exoplanets has both focused and expanded the search for
extraterrestrial intelligence. The consideration of Earth as an exoplanet, the
knowledge of the orbital parameters of individual exoplanets, and our new
understanding of the prevalence of exoplanets throughout the galaxy have all
altered the search strategies of communication SETI efforts, by inspiring new
"Schelling points" (i.e. optimal search strategies for beacons). Future efforts
to characterize individual planets photometrically and spectroscopically, with
imaging and via transit, will also allow for searches for a variety of
technosignatures on their surfaces, in their atmospheres, and in orbit around
them. In the near-term, searches for new planetary systems might even turn up
free-floating megastructures.Comment: 9 page invited review. v2 adds some references and v3 has other minor
additions and modification
Spin-orbit density wave induced hidden topological order in URu2Si2
The conventional order parameters in quantum matters are often characterized
by 'spontaneous' broken symmetries. However, sometimes the broken symmetries
may blend with the invariant symmetries to lead to mysterious emergent phases.
The heavy fermion metal URu2Si2 is one such example, where the order parameter
responsible for a second-order phase transition at Th = 17.5 K has remained a
long-standing mystery. Here we propose via ab-initio calculation and effective
model that a novel spin-orbit density wave in the f-states is responsible for
the hidden-order phase in URu2Si2. The staggered spin-orbit order 'spontaneous'
breaks rotational, and translational symmetries while time-reversal symmetry
remains intact. Thus it is immune to pressure, but can be destroyed by magnetic
field even at T = 0 K, that means at a quantum critical point. We compute
topological index of the order parameter to show that the hidden order is
topologically invariant. Finally, some verifiable predictions are presented.Comment: (v2) Substantially modified from v1, more calculation and comparison
with experiments are include
Charged, conformal non-relativistic hydrodynamics
We embed a holographic model of an U(1) charged fluid with Galilean
invariance in string theory and calculate its specific heat capacity and
Prandtl number. Such theories are generated by a R-symmetry twist along a null
direction of a N=1 superconformal theory. We study the hydrodynamic properties
of such systems employing ideas from the fluid-gravity correspondence.Comment: 31 pages, 1 figure, JHEP3 style, refs added, typos corrected, missing
terms in spatial charge current and field corrections added, to be published
in JHE
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