645 research outputs found
Security in Wireless Sensor Networks: Issues and Challenges
Wireless Sensor Network (WSN) is an emerging technology that shows great
promise for various futuristic applications both for mass public and military.
The sensing technology combined with processing power and wireless
communication makes it lucrative for being exploited in abundance in future.
The inclusion of wireless communication technology also incurs various types of
security threats. The intent of this paper is to investigate the security
related issues and challenges in wireless sensor networks. We identify the
security threats, review proposed security mechanisms for wireless sensor
networks. We also discuss the holistic view of security for ensuring layered
and robust security in wireless sensor networks.Comment: 6 page
Existence of a global weak solution to Compressible Primitive Equations
In this Note, we show a global weak existence result for a two dimensional Compressible Primitive Equations for atmosphere dynamics modeling
The effect of cultural orientation and leadership style on self- versus other-oriented organizational citizenship behavior in Turkey and the Netherlands
This paper investigated the effects of a paternalistic and empowering leadership style on organizational citizenship behaviour (OCB) in an experimental design using 100 Turkish and 100 Dutch students who held part-time jobs. Confirming our expectations, a paternalistic leadership style had a more positive effect on job dedication and organizational support in Turkey than in the Netherlands. Contradicting our expectations, an empowering leadership style did not have a more positive effect on any of the OCB dimensions in the Netherlands than it did in Turkey. However, in the Netherlands an empowering leadership style had a stronger effect on interpersonal facilitation, job dedication, and organizational support than a paternalistic leadership style. Paternalistic and empowering leadership styles both had positive effects on OCB dimensions in Turkey. As expected, collectivism moderated the relationship between paternalistic leadership style and other oriented OCB (i.e., interpersonal facilitation). Specifically, people who had more collectivistic tendencies were more positively influenced by a paternalistic leader than people who had low collectivistic tendencies in both countries. However, individualism did not have any moderating effects on the relationship between empowering leadership style and self-oriented OCB (i.e., job dedication). Our findings are relevant for understanding the effects of leadership styles and cultural orientations on self- versus other-oriented OCB in Turkey and the Netherlands
Compressible primitive equation: formal derivation and stability of weak solutions
We present a formal derivation of a simplified version of Compressible
Primitive Equations (CPEs) for atmosphere modeling. They are obtained from
-D compressible Navier-Stokes equations with an \emph{anisotropic viscous
stress tensor} where viscosity depends on the density. We then study the
stability of the weak solutions of this model by using an intermediate model,
called model problem, which is more simple and practical, to achieve the main
result
Wannier-function approach to spin excitations in solids
We present a computational scheme to study spin excitations in magnetic
materials from first principles. The central quantity is the transverse spin
susceptibility, from which the complete excitation spectrum, including
single-particle spin-flip Stoner excitations and collective spin-wave modes,
can be obtained. The susceptibility is derived from many-body perturbation
theory and includes dynamic correlation through a summation over ladder
diagrams that describe the coupling of electrons and holes with opposite spins.
In contrast to earlier studies, we do not use a model potential with adjustable
parameters for the electron-hole interaction but employ the random-phase
approximation. To reduce the numerical cost for the calculation of the
four-point scattering matrix we perform a projection onto maximally localized
Wannier functions, which allows us to truncate the matrix efficiently by
exploiting the short spatial range of electronic correlation in the partially
filled d or f orbitals. Our implementation is based on the FLAPW method.
Starting from a ground-state calculation within the LSDA, we first analyze the
matrix elements of the screened Coulomb potential in the Wannier basis for the
3d transition-metal series. In particular, we discuss the differences between a
constrained nonmagnetic and a proper spin-polarized treatment for the
ferromagnets Fe, Co, and Ni. The spectrum of single-particle and collective
spin excitations in fcc Ni is then studied in detail. The calculated spin-wave
dispersion is in good overall agreement with experimental data and contains
both an acoustic and an optical branch for intermediate wave vectors along the
[100] direction. In addition, we find evidence for a similar double-peak
structure in the spectral function along the [111] direction.Comment: 16 pages, 11 figures, 5 table
Propagation of diffraction-free and accelerating laser beams in turbid media
We experimentally investigate propagation of laser beams with Gaussian, Bessel and Airy transverse profiles in turbid media. We evaluate and compare the self-healing properties of these beams
P2X7 and A2A receptor endogenous activation protects against neuronal death caused by CoCl2-induced photoreceptor toxicity in the zebrafish retina
Injured retinas in mammals do not regenerate and heal with loss of function. The adult retina of zebrafish self-repairs after damage by activating cell-intrinsic mechanisms, which are regulated by extrinsic signal interactions. Among relevant regulatory extrinsic systems, purinergic signaling regulates progenitor proliferation during retinogenesis and regeneration and glia proliferation in proliferative retinopathies. ATP-activated P2X7 (P2RX7) and adenosine (P1R) receptors are involved in the progression of almost all retinopathies leading to blindness. Here, we examined P2RX7 and P1R participation in the retina regenerative response induced by photoreceptor damage caused by a specific dose of CoCl2. First, we found that treatment of uninjured retinas with a potent agonist of P2RX7 (BzATP) provoked photoreceptor damage and mitotic activation of multipotent progenitors. In CoCl2-injured retinas, blockade of endogenous extracellular ATP activity on P2RX7 caused further neurodegeneration, Müller cell gliosis, progenitor proliferation, and microglia reactivity. P2RX7 inhibition in injured retinas also increased the expression of lin28a and tnfα genes, which are related to multipotent progenitor proliferation. Levels of hif1α, vegf3r, and vegfaa mRNA were enhanced by blockade of P2RX7 immediately after injury, indicating hypoxic like damage and endothelial cell growth and proliferation. Complete depletion of extracellular nucleotides with an apyrase treatment strongly potentiated cell death and progenitor proliferation induced with CoCl2. Blockade of adenosine P1 and A2A receptors (A2AR) had deleterious effects and deregulated normal timing for progenitor and precursor cell proliferation following photoreceptor damage. ATP via P2RX7 and adenosine via A2AR are survival extracellular signals key for retina regeneration in zebrafish.Fil: Medrano, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Pisera Fuster, Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Bernabeu, Ramon Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Faillace, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentin
Peacock Bundles: Bundle Coloring for Graphs with Globality-Locality Trade-off
Bundling of graph edges (node-to-node connections) is a common technique to
enhance visibility of overall trends in the edge structure of a large graph
layout, and a large variety of bundling algorithms have been proposed. However,
with strong bundling, it becomes hard to identify origins and destinations of
individual edges. We propose a solution: we optimize edge coloring to
differentiate bundled edges. We quantify strength of bundling in a flexible
pairwise fashion between edges, and among bundled edges, we quantify how
dissimilar their colors should be by dissimilarity of their origins and
destinations. We solve the resulting nonlinear optimization, which is also
interpretable as a novel dimensionality reduction task. In large graphs the
necessary compromise is whether to differentiate colors sharply between locally
occurring strongly bundled edges ("local bundles"), or also between the weakly
bundled edges occurring globally over the graph ("global bundles"); we allow a
user-set global-local tradeoff. We call the technique "peacock bundles".
Experiments show the coloring clearly enhances comprehensibility of graph
layouts with edge bundling.Comment: Appears in the Proceedings of the 24th International Symposium on
Graph Drawing and Network Visualization (GD 2016
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Scope and Predictive Genetic/Phenotypic Signatures of Bicarbonate (NaHCO3) Responsiveness and β-Lactam Sensitization in Methicillin-Resistant Staphylococcus aureus.
Addition of sodium bicarbonate (NaHCO3) to standard antimicrobial susceptibility testing medium reveals certain methicillin-resistant Staphylococcus aureus (MRSA) strains to be highly susceptible to β-lactams. We investigated the prevalence of this phenotype (NaHCO3 responsiveness) to two β-lactams among 58 clinical MRSA bloodstream isolates. Of note, ∼75% and ∼36% of isolates displayed the NaHCO3 responsiveness phenotype to cefazolin (CFZ) and oxacillin (OXA), respectively. Neither intrinsic β-lactam MICs in standard Mueller-Hinton broth (MHB) nor population analysis profiles were predictive of this phenotype. Several genotypic markers (clonal complex 8 [CC8]; agr I and spa t008) were associated with NaHCO3 responsiveness for OXA
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