5,588 research outputs found
Testing a quintessence model with CMBR peaks location
We show that a model of quintessence with exponential potential, which allows
to obtain general exact solutions, can generate locations of CMBR peaks which
are fully compatible with present observational dataComment: 7 pages, no figure
What does it take to evolve behaviorally complex organisms?
What genotypic features explain the evolvability of organisms that have to accomplish many different tasks? The genotype of behaviorally complex organisms may be more likely to encode modular neural architectures because neural modules dedicated to distinct tasks avoid neural interference, i.e., the arrival of conflicting messages for changing the value of connection weights during learning. However, if the connection weights for the various modules are genetically inherited, this raises the problem of genetic linkage: favorable mutations may fall on one portion of the genotype encoding one neural module and unfavorable mutations on another portion encoding another module. We show that this can prevent the genotype from reaching an adaptive optimum. This effect is different from other linkage effects described in the literature and we argue that it represents a new class of genetic constraints. Using simulations we show that sexual reproduction can alleviate the problem of genetic linkage by recombining separate modules all of which incorporate either favorable or unfavorable mutations. We speculate that this effect may contribute to the taxonomic prevalence of sexual reproduction among higher organisms. In addition to sexual recombination, the problem of genetic linkage for behaviorally complex organisms may be mitigated by entrusting evolution with the task of finding appropriate modular architectures and learning with the task of finding the appropriate connection weights for these architectures
La valutazione del merito creditizio in agricoltura alla luce dellâAccordo Basilea 2: un applicazione ad unâimpresa floricola
The marketsâ globalisation induces the national agriculture sector to improve its competitiveness by structural adjustment of the farms. This process requires financial resources so that new and more intensive relations will be necessary between bank and farm. From this point of view the new agreement named Basilea 2 is seen as a potential threat that may reduce the capability to credit access for the agricultural entrepreneurs. For this reason this study has verified the principal aspects that will influence the assessment of the farmsâ rating by applying the procedure in a floricultural farm. A sensitive analysis has been developed in order to evaluate if the new agreement constitutes a threat or an opportunity for the farm in receiving funds from the bank
Theoretical analysis of aliasing noises in cold atom Mach-Zehnder interferometers
We present a theoretical analysis of aliasing noises that might appear in cold atom Mach-Zehnder interferometers used for the measurement of various physical quantities. We focus more specifically on single cold atom gyroscopes. To evaluate the level of aliasing noises, we have developed a model based on the power spectral densities of the different identified noise sources as input parameters and which makes use of a servo-loop to realize a precise measurement of the rotation rate. The model allows one to take into account different modes of operation, like a continuous as well as a pulsed or even a multi-ball operation. For monokinetic atoms, we show that the intermodulation noise can be completely filtered out with a continuous mode of operation and an optimum modulation scheme for any modulation frequency but also with a pulsed operation however only for specific launching frequencies. In the case of a real continuous atomic beam having a velocity distribution, it comes out that a high attenuation can be reached which indicates clearly the potential stability improvement that can be expected from a continuous operatio
Direct test of time-reversal symmetry in the entangled neutral kaon system at a -factory
We present a novel method to perform a direct T (time reversal) symmetry test
in the neutral kaon system, independent of any CP and/or CPT symmetry tests.
This is based on the comparison of suitable transition probabilities, where the
required interchange of in out states for a given process is obtained
exploiting the Einstein-Podolsky-Rosen correlations of neutral kaon pairs
produced at a -factory. In the time distribution between the two decays,
we compare a reference transition like the one defined by the time ordered
decays with the T -conjugated one defined by . With the use of this and other T conjugated comparisons, the KLOE-2
experiment at DANE could make a significant test
Molecular and morphological phylogeny of Saccocirridae (Annelida) reveals two cosmopolitan clades with specific habitat preferences
Saccocirrids are tiny, slender annelids inhabiting the interstices among coarse sand sediments in shallow waters. The 22 nominal species can be grouped into two morphological groups "papillocercus"and "krusadensis", based on the absence/presence of a pharyngeal bulbus muscle, absence/presence of ventral ciliary patterns, bilateral/unilateral gonad arrangement and chaetal differences. We present herein the first phylogenetic analyses of Saccocirridae based on four molecular markers and 34 morphological characters, employing maximum likelihood and Bayesian methods. All analyses confirmed the monophyly of each morphological group with high nodal support. As a consequence and based on several apomorphic characters, a new genus, Pharyngocirrus gen. nov., is erected for the "krusadensis"clade. Remarkably, the habitat preferences and trophic guilds are also shown to differ between the two genera, yet show strong consistency within each group. Geographic distribution analyses underscore the family preference for subtropical areas, but reject the previously proposed restriction of Pharyngocirrus gen. nov. to the Indo-Pacific. The finding of two morphologically diverging, cosmopolitan sister clades with different habitat preferences suggest an early ecological diversification of the family, conserved during the later evolution, speciation processes and dispersal of the family75202218CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESP140611/2008-82012/08581-0; 2013/04358-7Det Frie Forskningsrad (DFF); Carlsberg Foundation; Reserva de la Biosfera (Government of Lanzarote
Quantum marking and quantum erasure for neutral kaons
Entangled K0 anti-K0 pairs are shown to be suitable to discuss extensions and
tests of Bohr's complementarity principle through the quantum marking and
quantum erasure techniques suggested by M. O. Scully and K. Druehl [Phys. Rev.
A 25, 2208 (1982)]. Strangeness oscillations play the role of the traditional
interference pattern linked to wave-like behaviour, whereas the distinct
propagation in free space of the K_S and K_L components mimics the two possible
interferometric paths taken by particle-like objects.Comment: 4 RevTeX page
Kaon physics with the KLOE detector
In this paper we discuss the recent finalized analyses by the KLOE experiment
at DANE: the CPT and Lorentz invariance test with entangled pairs, and the precision measurement of the branching fraction of
the decay . We also present the
status of an ongoing analysis aiming to precisely measure the mass
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