3,766 research outputs found
Damage Spreading and Criticality in Finite Random Dynamical Networks
We systematically study and compare damage spreading at the sparse
percolation (SP) limit for random boolean and threshold networks with
perturbations that are independent of the network size . This limit is
relevant to information and damage propagation in many technological and
natural networks. Using finite size scaling, we identify a new characteristic
connectivity , at which the average number of damaged nodes ,
after a large number of dynamical updates, is independent of . Based on
marginal damage spreading, we determine the critical connectivity
for finite at the SP limit and show that it
systematically deviates from , established by the annealed approximation,
even for large system sizes. Our findings can potentially explain the results
recently obtained for gene regulatory networks and have important implications
for the evolution of dynamical networks that solve specific computational or
functional tasks.Comment: 4 pages, 4 eps figure
Annual and semiannual variations of vertical total electron content during high solar activity based on GPS observations
Annual, semiannual and seasonal variations of the Vertical Total Electron
Content (VTEC) have been investigated during high solar activity in 2000. In
this work we use Global IGS VTEC maps and Principal Component Analysis to
study spatial and temporal ionospheric variability. The behavior of VTEC
variations at two-hour periods, at noon and at night is analyzed. Particular
characteristics associated with each period and the geomagnetic regions are
highlighted.
<br><br>
The variations at night are smaller than those obtained at noon. At noon it
is possible to see patterns of the seasonal variation at high latitude, and
patterns of the semiannual anomaly at low latitudes with a slow decrease
towards mid latitudes. At night there is no evidence of seasonal or annual
anomaly for any region, but it was possible to see the semiannual anomaly at
low latitudes with a sudden decrease towards mid latitudes. In general, the
semiannual behavior shows MarchâApril equinox at least 40 % higher than
September one. Similarities and differences are analyzed also with regard to
the same analysis done for a period of low solar activity
Molecular dynamics simulations of reflection and adhesion behavior in Lennard-Jones cluster deposition
We conduct molecular dynamics simulations of the collision of atomic clusters
with a weakly-attractive surface. We focus on an intermediate regime, between
soft-landing and fragmentation, where the cluster undergoes deformation on
impact but remains largely intact, and will either adhere to the surface (and
possibly slide), or be reflected. We find that the outcome of the collision is
determined by the Weber number, We i.e. the ratio of the kinetic energy to the
adhesion energy, with a transition between adhesion and reflection occurring as
We passes through unity. We also identify two distinct collision regimes: in
one regime the collision is largely elastic and deformation of the cluster is
relatively small but in the second regime the deformation is large and the
adhesion energy starts to depend on the kinetic energy. If the transition
between these two regimes occurs at a similar kinetic energy to that of the
transition between reflection and adhesion, then we find that the probability
of adhesion for a cluster can be bimodal. In addition we investigate the
effects of the angle of incidence on adhesion and reflection. Finally we
compare our findings both with recent experimental results and with macroscopic
theories of particle collisions.Comment: 18 pages, 13 figure
Towards semantic software engineering environments
Software tools processing partially common set of data should share an understanding of what these data mean. Since ontologies have been used to express formally a shared understanding of information, we argue that they are a way towards Semantic SEEs. In this paper we discuss an ontology-based approach to tool integration and present ODE, an ontology-based SEE
Temporal and diffraction effects in entanglement creation in an optical cavity
A practical scheme for entanglement creation between distant atoms located
inside a single-mode optical cavity is discussed. We show that the degree of
entanglement and the time it takes for the entanglement to reach its optimum
value is a sensitive function the initial conditions and the position of the
atoms inside the cavity mode. It is found that the entangled properties of the
two atoms can readily be extracted from dynamics of a simple two-level system.
Effectively, we engineer two coupled qubits whose the dynamics are analogous to
that of a driven single two-level system. It is found that spatial variations
of the coupling constants actually help to create transient entanglement which
may appear on the time scale much longer than that predicted for the case of
equal coupling constants. When the atoms are initially prepared in an entangled
state, they may remain entangled for all times. We also find that the
entanglement exhibits an interesting phenomenon of diffraction when the the
atoms are located between the nodes and antinodes of the cavity mode. The
diffraction pattern of the entanglement varies with time and we explain this
effect in terms of the quantum property of complementarity, which is manifested
as a tradeoff between the knowledge of energy of the exchanged photon versus
the evolution time of the system.Comment: Phys. Rev. A75, 042307 (2007
Syphilis iridocyclitis in a patient with type 1 diabetes
We present a rare cause of iridocyclitis in a patient with vitiligo and type 1 diabetes who showed poor metabolic control, and suffered from remitting fever, weight loss, fatigue, diffuse arthralgias and reduced visual acuity. Mild systemic symptoms coupled with increased cholestasis enzymes, insulin resistance, mild inflammation and a functioning adrenal gland focused our clinical work-up on granulomatous causes of iridocyclitis. Specific tests confirmed syphilis, with no involvement of the central nervous system. Ocular syphilis, despite being unusual, can be the only manifestation of the disease. The work-up of any unexplained ocular inflammation should include testing for syphilis so as to not delay the diagnosis
Annual and semiannual variations of vertical total electron content during high solar activity based on GPS observations
Annual, semiannual and seasonal variations of theVertical Total Electron Content (VTEC) have been investigatedduring high solar activity in 2000. In this work we useGlobal IGS VTEC maps and Principal Component Analysisto study spatial and temporal ionospheric variability. The behaviorof VTEC variations at two-hour periods, at noon andat night is analyzed. Particular characteristics associated witheach period and the geomagnetic regions are highlighted.The variations at night are smaller than those obtained atnoon. At noon it is possible to see patterns of the seasonalvariation at high latitude, and patterns of the semiannualanomaly at low latitudes with a slow decrease towards midlatitudes. At night there is no evidence of seasonal or annualanomaly for any region, but it was possible to see the semiannualanomaly at low latitudes with a sudden decrease towardsmid latitudes. In general, the semiannual behavior showsMarchâApril equinox at least 40% higher than Septemberone. Similarities and differences are analyzed also with regardto the same analysis done for a period of low solar activity.Fil: Natali, Maria Paula. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata; ArgentinaFil: Meza, A.. Universidad Nacional de La Plata. Facultad de Ciencias AstronĂłmicas y GeofĂsicas; Argentin
Collaborators, Collaboration, and the Problems of Empire in Napoleonic Italy, The Oppizzoni Affair, 1805-1807
The recent bicentennial commemorations of the Napoleonic empire have witnessed a proliferation of new studies. Scholars now possess much more sophisticated conceptual tools than in past decades with which to gauge the problems faced by French imperial administrators throughout Europe. Well-trodden concepts, like centre/periphery or collaboration/resistance, have been reinvigorated by more sophisticated understandings of how rulers and ruled interacted in the early nineteenth century. This article argues that, while much progress has been made in understanding problems of âresistanceâ, there is more to be said about the other side of the same coin, namely: âcollaborationâ. Using the micro/local history of a scandal in Napoleonic Bologna, this article wishes to reaffirm that collaboration was an active agent that shaped, and often shook, the French imperial project. The biggest problem remained that, despite âgood intentionsâ, collaborators sometimes simply did not collaborate with each other. After all, imperial clients were determined to benefit from the experience of empire. The centre was often submerged by local petty squabbles. This article will use a specific micro-history in Bologna to highlight the extent to which Napoleonic empire builders had to thread a fine line between the impracticalities of direct control and the dangers of âgoing nativeâ
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