9,532 research outputs found
On the strategy frequency problem in batch Minority Games
Ergodic stationary states of Minority Games with S strategies per agent can
be characterised in terms of the asymptotic probabilities with which
an agent uses of his strategies. We propose here a simple and general
method to calculate these quantities in batch canonical and grand-canonical
models. Known analytic theories are easily recovered as limiting cases and, as
a further application, the strategy frequency problem for the batch
grand-canonical Minority Game with S=2 is solved. The generalization of these
ideas to multi-asset models is also presented. Though similarly based on
response function techniques, our approach is alternative to the one recently
employed by Shayeghi and Coolen for canonical batch Minority Games with
arbitrary number of strategies.Comment: 17 page
Swift J0525.6+2416 and IGR J04571+4527: two new hard X-ray selected magnetic cataclysmic variables identified with XMM-Newton
IGR J04571+4527 and Swift J0525.6+2416 are two hard X-ray sources detected in
the Swift/BAT and INTEGRAL/IBIS surveys. They were proposed to be magnetic
cataclysmic variables of the Intermediate Polar (IP) type, based on optical
spectroscopy. IGR J04571+4527 also showed a 1218 s optical periodicity,
suggestive of the rotational period of a white dwarf, further pointing towards
an IP classification. We here present detailed X-ray (0.3-10 keV) timing and
spectral analysis performed with XMM-Newton, complemented with hard X-ray
coverage (15-70 keV) from Swift/BAT. These are the first high signal to noise
observations in the soft X-ray domain for both sources, allowing us to identify
the white dwarf X-ray spin period of Swift J0525.6+2416 (226.28 s), and IGR
J04571+4527 (1222.6 s). A model consisting of multi-temperature optically thin
emission with complex absorption adequately fits the broad-band spectrum of
both sources. We estimate a white dwarf mass of about 1.1 and 1.0 solar masses
for IGR J04571+4527 and Swift J0525.6+2416, respectively. The above
characteristics allow us to unambiguously classify both sources as IPs,
confirming the high incidence of this subclass among hard X-ray emitting
Cataclysmic Variables.Comment: 8 pages, 4 figures, 3 tables. Accepted for publication in MNRA
Reaction networks as systems for resource allocation: A variational principle for their non-equilibrium steady states
Within a fully microscopic setting, we derive a variational principle for the non-equilibrium steady states of chemical reaction networks, valid for time-scales over which chemical potentials can be taken to be slowly varying: at stationarity the system minimizes a global function of the reaction fluxes with the form of a Hopfield Hamiltonian with Hebbian couplings, that is explicitly seen to correspond to the rate of decay of entropy production over time. Guided by this analogy, we show that reaction networks can be formally re-cast as systems of interacting reactions that optimize the use of the available compounds by competing for substrates, akin to agents competing for a limited resource in an optimal allocation problem. As an illustration, we analyze the scenario that emerges in two simple cases: that of toy (random) reaction networks and that of a metabolic network model of the human red blood cell. © 2012 De Martino et al
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Management of functional neurological disorder.
Functional neurological disorder (FND) is a common cause of persistent and disabling neurological symptoms. These symptoms are varied and include abnormal control of movement, episodes of altered awareness resembling epileptic seizures and abnormal sensation and are often comorbid with chronic pain, fatigue and cognitive symptoms. There is increasing evidence for the role of neurologists in both the assessment and management of FND. The aim of this review is to discuss strategies for the management of FND by focusing on the diagnostic discussion and general principles, as well as specific treatment strategies for various FND symptoms, highlighting the role of the neurologist and proposing a structure for an interdisciplinary FND service
Two-dimensional conical dispersion in ZrTe5 evidenced by optical spectroscopy
Zirconium pentatelluride was recently reported to be a 3D Dirac semimetal,
with a single conical band, located at the center of the Brillouin zone. The
cone's lack of protection by the lattice symmetry immediately sparked vast
discussions about the size and topological/trivial nature of a possible gap
opening. Here we report on a combined optical and transport study of ZrTe5,
which reveals an alternative view of electronic bands in this material. We
conclude that the dispersion is approximately linear only in the a-c plane,
while remaining relatively flat and parabolic in the third direction (along the
b axis). Therefore, the electronic states in ZrTe5 cannot be described using
the model of 3D Dirac massless electrons, even when staying at energies well
above the band gap 6 meV found in our experiments at low temperatures.Comment: Physical Review Letters 122, 217402 (2019). Corrected acknowledgment
Typical properties of optimal growth in the Von Neumann expanding model for large random economies
We calculate the optimal solutions of the fully heterogeneous Von Neumann
expansion problem with processes and goods in the limit .
This model provides an elementary description of the growth of a production
economy in the long run. The system turns from a contracting to an expanding
phase as increases beyond . The solution is characterized by a universal
behavior, independent of the parameters of the disorder statistics. Associating
technological innovation to an increase of , we find that while such an
increase has a large positive impact on long term growth when , its
effect on technologically advanced economies () is very weak.Comment: 8 pages, 1 figur
Broad-band characteristics of seven new hard X-ray selected cataclysmic variables
IndexaciĂłn: Web of Science; Scopus.We present timing and spectral analysis of a sample of seven hard X-ray selected cataclysmic
variable candidates based on simultaneous X-ray and optical observations collected
with XMMâNewton, complemented with Swift/BAT and INTEGRAL /IBIS hard X-ray data
and ground-based optical photometry. For six sources, X-ray pulsations are detected for the
first time in the range of âŒ296â6098 s, identifying them as members of the magnetic class.
Swift J0927.7â6945, Swift J0958.0â4208, Swift J1701.3â4304, Swift J2113.5+5422 and
possibly PBC J0801.2â4625 are intermediate polars (IPs), while Swift J0706.8+0325 is a
short (1.7 h) orbital period polar, the 11th hard X-ray-selected identified so far. X-ray orbital
modulation is also observed in Swift J0927.7â6945 (5.2 h) and Swift J2113.5+5422
(4.1 h). Swift J1701.3â4304 is discovered as the longest orbital period (12.8 h) deep eclipsing
IP. The spectra of the magnetic systems reveal optically thin multitemperature emission
between 0.2 and 60 keV. Energy-dependent spin pulses and the orbital modulation in
Swift J0927.7â6945 and Swift J2113.5+5422 are due to intervening local high-density absorbing
material (NH ⌠1022 â 23 cmâ2). In Swift J0958.0â4208 and Swift J1701.3â4304, a
soft X-ray blackbody (kT ⌠50 and âŒ80 eV) is detected, adding them to the growing group
of âsoftâ IPs. White dwarf masses are determined in the range of âŒ0.58â1.18 M, indicating
massive accreting primaries in five of them. Most sources accrete at rates lower than the
expected secular value for their orbital period. Formerly proposed as a long-period (9.4 h)
nova-like CV, Swift J0746.3â1608 shows peculiar spectrum and light curves suggesting either
an atypical low-luminosity CV or a low-mass X-ray binary.https://academic.oup.com/mnras/article/470/4/4815/390658
Three years field trials to assess the effect of kaolin made particles and copper on olive-fruit fly (B.oleae Gmelin) infestations in Sicily
In most countries of Mediterranean Basin, Bactrocera oleae (Gmel), the olive fruit fly, is the key pest insect on olives. In Sicily this pest causes losses of fruits and a poor quality olive oil. Many researchers have recently carried out some field studies which were based on the use of kaolin and copper against the olive-fruit fly. In the last years these products have been effective several times in reducing olive fly infestation. Kaolin had, also, some important effect in reducing heat-stress in fruit crops and olive-trees.
The aim of the present study was to assess the effect of kaolin and copper treatment on olive infestations in Sicily and to evaluate chemical and sensory parameters of oils extracted. For this reason, within 2003-2005, the IX Servizio of Assessorato Regionale Agricoltura e Foreste, selected some olive groves where to carry out trials with kaolin and copper and to realize information and divulgation activities
Investigation of creep phenomenon on composite material for bolt connections
One of the main target in the automotive design is the weight reduction. This reduction leads to the reduction of the gas emissions. The designers tend to use innovative materials for the automotive field such as plastics and composites. To use the right material for the right application, multi material solutions are increasingly adopted. To join dissimilar materials, solutions like adhesive, bolt and nuts, riveting are necessary. It is necessary to know the behaviour of the materials to be joined, under different loading conditions to ensure the joint. In this work, a bolt connection between composite and aluminium plates has been considered. The behaviour of a carbon fibre reinforced material under compression load, taking into account creep is studied. A specific experimental equipment has been design and built. A series of experimental compressive tests, in the laminate thickness direction, have been done on carbon fibre reinforced material specimens. Different set-up in terms of temperature, compression load and surface roughness have been investigated. The obtained results are presented and discussed. A mathematical model will be proposed for interpolation of the obtained results. Finally, a possible strategy for reducing the tight loss in the initial phase of the joint life is propose
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