3,243 research outputs found

    French Canadian Participation in the War of 1812: A Social Study of the Voltiguers Canadians

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    During the War of 1812, the participation of French Canadians in colonial militia units such as the Voltigeurs Canadiens was of great importance for the defence of Lower Canada. The colony’s lack of regular British toops combined with threats of American invasion rendered crucial to the mobilization of the local populace, most of which was of French descent. Although lacking the discipline and structure of British regular soldiers. Lower-Canadian militiamen were able to neutralize numerous American invasion attempts. Altogether, this impressive participation in the war effort helped redefine the military character of French Canadians. It also dissipated the British authorities’ fears that French Canadians were disloyal subjects. This study analyses the military organization of the Voltigeurs Canadiens to demonstrate the importance of French Canadian participation in the war, especially in Lower Canada, their military campaigns and how the Voltigeurs’ victories became the pride of all French Canada

    The Right Mutation Strength for Multi-Valued Decision Variables

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    The most common representation in evolutionary computation are bit strings. This is ideal to model binary decision variables, but less useful for variables taking more values. With very little theoretical work existing on how to use evolutionary algorithms for such optimization problems, we study the run time of simple evolutionary algorithms on some OneMax-like functions defined over Ω={0,1,,r1}n\Omega = \{0, 1, \dots, r-1\}^n. More precisely, we regard a variety of problem classes requesting the component-wise minimization of the distance to an unknown target vector zΩz \in \Omega. For such problems we see a crucial difference in how we extend the standard-bit mutation operator to these multi-valued domains. While it is natural to select each position of the solution vector to be changed independently with probability 1/n1/n, there are various ways to then change such a position. If we change each selected position to a random value different from the original one, we obtain an expected run time of Θ(nrlogn)\Theta(nr \log n). If we change each selected position by either +1+1 or 1-1 (random choice), the optimization time reduces to Θ(nr+nlogn)\Theta(nr + n\log n). If we use a random mutation strength i{0,1,,r1}ni \in \{0,1,\ldots,r-1\}^n with probability inversely proportional to ii and change the selected position by either +i+i or i-i (random choice), then the optimization time becomes Θ(nlog(r)(log(n)+log(r)))\Theta(n \log(r)(\log(n)+\log(r))), bringing down the dependence on rr from linear to polylogarithmic. One of our results depends on a new variant of the lower bounding multiplicative drift theorem.Comment: an extended abstract of this work is to appear at GECCO 201

    Ultra-High-Energy Cosmic Rays from the Radio Lobes of AGNs

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    In the past year, the HiRes and Auger collaborations have reported the discovery of a high-energy cutoff in the ultra-high energy cosmic-ray (UHECR) spectrum, and an apparent clustering of the highest energy events towards nearby active galactic nuclei (AGNs). Consensus is building that such 1019\sim 10^{19}--102010^{20} eV particles are accelerated within the radio-bright lobes of these sources, but it is not yet clear how this actually happens. In this paper, we report (to our knowledge) the first treatment of stochastic particle acceleration in such environments from first principles, showing that energies 1020\sim 10^{20} eV are reached in 106\sim 10^6 years for protons. However, our findings reopen the question regarding whether the high-energy cutoff is due solely to propagation effects, or whether it does in fact represent the maximum energy permitted by the acceleration process itself.Comment: 8 pages, 7 figures, acccepted for publication in MNRA

    On the influence of statistics on the determination of the mean value of the depth of shower maximum for ultra high energy cosmic ray showers

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    The chemical composition of ultra high energy cosmic rays is still uncertain. The latest results obtained by the Pierre Auger Observatory and the HiRes Collaboration, concerning the measurement of the mean value and the fluctuations of the atmospheric depth at which the showers reach the maximum development, Xmax, are inconsistent. From comparison with air shower simulations it can be seen that, while the Auger data may be interpreted as a gradual transition to heavy nuclei for energies larger than ~ 2-3x10^18 eV, the HiRes data are consistent with a composition dominated by protons. In Ref. [1] it is suggested that a possible explanation of the observed deviation of the mean value of Xmax from the proton expectation, observed by Auger, could originate in a statistical bias arising from the approximated exponential shape of the Xmax distribution, combined with the decrease of the number of events as a function of primary energy. In this paper we consider a better description of the Xmax distribution and show that the possible bias in the Auger data is at least one order of magnitude smaller than the one obtained when assuming an exponential distribution. Therefore, we conclude that the deviation of the Auger data from the proton expectation is unlikely explained by such statistical effect.Comment: To be published in Journal of Physics G: Nuclear and Particle Physic

    Global Production Increased by Spatial Heterogeneity in a Population Dynamics Model

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    Spatial and temporal heterogeneity are often described as important factors having a strong impact on biodiversity. The effect of heterogeneity is in most cases analyzed by the response of biotic interactions such as competition of predation. It may also modify intrinsic population properties such as growth rate. Most of the studies are theoretic since it is often difficult to manipulate spatial heterogeneity in practice. Despite the large number of studies dealing with this topics, it is still difficult to understand how the heterogeneity affects populations dynamics. On the basis of a very simple model, this paper aims to explicitly provide a simple mechanism which can explain why spatial heterogeneity may be a favorable factor for production.We consider a two patch model and a logistic growth is assumed on each patch. A general condition on the migration rates and the local subpopulation growth rates is provided under which the total carrying capacity is higher than the sum of the local carrying capacities, which is not intuitive. As we illustrate, this result is robust under stochastic perturbations

    Human Time-Frequency Acuity Beats the Fourier Uncertainty Principle

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    The time-frequency uncertainty principle states that the product of the temporal and frequency extents of a signal cannot be smaller than 1/(4π)1/(4\pi). We study human ability to simultaneously judge the frequency and the timing of a sound. Our subjects often exceeded the uncertainty limit, sometimes by more than tenfold, mostly through remarkable timing acuity. Our results establish a lower bound for the nonlinearity and complexity of the algorithms employed by our brains in parsing transient sounds, rule out simple "linear filter" models of early auditory processing, and highlight timing acuity as a central feature in auditory object processing.Comment: 4 pages, 2 figures; Accepted at PR

    L’allégorie dans la pensée grecque : de Théagène de Rhégium à Héraclite l’allégoriste

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    On considère traditionnellement l'interprétation allégorique comme une défense face aux critiques que les premiers philosophes Ioniens ont adressées aux poètes pour leur représentation de la divinité. Ainsi, l'allégorie grecque aurait été au coeur d'une polémique théologique entre les poètes et les philosophes ou plus largement au coeur de l’opposition de la philosophie au mythe. Il est pourtant désormais admis que la relation entre le logos et le muthos ne peut se réduire à une telle antinomie. Il est donc essentiel de redéfinir à son tour le rôle de l’allégorie afin de nuancer son caractère apologétique et son cadre polémique. L’entreprise a déjà été entamée par la recherche des deux dernières décennies et c’est dans cette actualisation historiographique que souhaite s’inscrire ce mémoire. L’organisation du développement est à la fois chronologique et thématique. L’examen de la réception des mythes à l’époque archaïque, celle du premier commentaire allégorique met en avant un aspect négligé de la critique philosophique : la réécriture du mythe théogonique en cosmologie philosophique. Cette réécriture n’est pas sans effet sur l’allégorie qui peut être conçue dès le Vème av. J.-C. comme un outil de réappropriation du mythe, à la fois dans sa matière et dans sa forme discursive, par la philosophie désormais affirmée. Enfin, la mise en perspective de l’allégorie avec les traditions discursives qui entourent sa naissance révèle que l’allégorie est certes le reflet d’une relation co-évolutive du logos et du muthos mais surtout la conséquence d’une conception du langage complexe dans la pensée grecque.Allegorical interpretation is traditionally seen as a defence against the criticism that the early Ionian philosophers levelled at the poets for their depiction of the deity. Thus, Greek allegory would have been at the heart of a theological polemic between poets and philosophers and more broadly at the heart of the opposition of philosophy to myth. It is now accepted, however, that the relationship between logos and muthos cannot be reduced to such an antinomy. It is therefore essential to redefine the role of allegory in order to nuance its apologetic character and its polemical framework. This undertaking has already been initiated by the research of the last two decades and it is in this historiographic update that this thesis wishes to be inscribed. The organisation of the development is both chronological and thematic. The examination of the reception of the myths in the archaic period, that of the first allegorical commentary, brings out a neglected aspect of the philosophical criticism: the rewriting of the theogonic myth in philosophical cosmology. This rewriting is not without effect on allegory, which can be conceived from the 5th century BC onwards as a tool for the reappropriation of myth, both in its subject and in its discursive form, by the philosophical discourse. Finally, putting allegory into perspective with the discursive traditions surrounding its birth reveals that allegory is the reflection of a co-evolutionary relationship between logos and muthos and above all the consequence of the idea of a complex language

    Dark matter scaling relations in intermediate z haloes

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    We investigate scaling relations between the dark matter (DM) halo model parameters for a sample of intermediate redshift early - type galaxies (ETGs) resorting to a combined analysis of Einstein radii and aperture velocity dispersions. Modeling the dark halo with a Navarro - Frenk - White profile and assuming a Salpeter initial mass function (IMF) to estimate stellar masses, we find that the column density S{\cal{S}} and the Newtonian acceleration within the halo characteristic radius rsr_s and effective radius ReffR_{eff} are not universal quantities, but correlate with the luminosity LVL_V, the stellar mass MM_{\star} and the halo mass M200M_{200}, contrary to recent claims in the literature. We finally discuss a tight correlation among the DM mass MDM(Reff)M_{DM}(R_{eff}) within the effective radius ReffR_{eff}, the stellar mass M(Reff)M_{\star}(R_{eff}) and ReffR_{eff} itself. The slopes of the scaling relations discussed here strongly depend, however, on the DM halo model and the IMF adopted so that these ingredients have to be better constrained in order to draw definitive conclusions on the DM scaling relations for ETGs.Comment: 8 pages, 1 figure, 4 tables, MNRAS submitted version (including corrections after the referee report

    SimProp: a Simulation Code for Ultra High Energy Cosmic Ray Propagation

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    A new Monte Carlo simulation code for the propagation of Ultra High Energy Cosmic Rays is presented. The results of this simulation scheme are tested by comparison with results of another Monte Carlo computation as well as with the results obtained by directly solving the kinetic equation for the propagation of Ultra High Energy Cosmic Rays. A short comparison with the latest flux published by the Pierre Auger collaboration is also presented.Comment: 19 pages, 12 eps figures, version accepted for publication in JCA
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