Double power laws, fractals and self-similarity

Power law (PL) distributions have been largely reported in the modeling of distinct real phenomena and have been associated with fractal structures and self-similar systems. In this paper, we analyze real data that follows a PL and a double PL behavior and verify the relation between the PL coefficient and the capacity dimension of known fractals. It is to be proved a method that translates PLs coefficients into capacity dimension of fractals of any real data

MOLECULAR ANALYSIS OF DOUBLE FERTILIZATION PROCESS IN ARABIDOPSIS

Fertilization and seed formation are key events in the life cycle of flowering plants. The seed represents an elaborated functional unit, whose main purpose is to propagate the plant's offspring. The first step in seed development is the formation of ovules and subsequently the achievement of a successful double fertilization process. In our lab we have discovered that the MADS-box domain protein complex formed by SEEDSTICK (STK) and SEPALLATA3 (SEP3), responsible to maintain ovule identity, have as a direct target a member of the REM family, VERDANDI (VDD, REM20). With the combination of Bio-informatics studies and ChIP-qPCR experiments using specific STK and SEP3 antibodies, we were able to identify REM11, as the second direct target of the STK-SEP3 complex. The phenotype of the rem11 mutant is very similar to the one described for vdd-1/+ demonstrating that REM11 plays a similar function in the fertilization process. To better understand the fertilization defect observed in these mutants we have used a new technique developed to observe fertilization in vivo, by visualizing the gametes with a combination of markers for sperm cells and for the female gamete. In the rem11 or in vdd-1 gametophytes the synergid cell seemed to lose identity. Although the pollen tubes reached the micropyle, the two sperm cells didn\u2019t migrate toward the egg and center cells. These results showed the important and the direct involvement of these two genes in the control of synergid driven processes. Ultimately we discovered that genes responsible for the pollen tube attraction like the transcription factor MYB98, are correctly expressed in the mutants whereas genes, probably responsible for the degeneration process are miss-expressed. In summary, we can say that, two very different processes are regulated by the synergid cells: 1) the attraction of the pollen tube and 2) the synergid degeneration (apoptosis). We discover that the second step is specifically controlled by VDD and REM11, two proteins that by yeast-2-hybrid experiments were able to interact. Based on these results we have decided to study if other REM transcription factors could interact with REM11 and VDD. In conclusion STK-SEP3 MADS-box complex are able to directly regulate a REM transcription factor complex that has a very important and specific role during the double fertilization process. To understand how VDD-REM11 complex regulate synergid degeneration we have performed a RNA sequencing experiment comparing wild-type mature carpels to mutant ones. Exciting targets have been discovered and discuss in this thesis. I have also studied the regulation of VDD transcription by STK-SEP3 complex. In VDD regulatory region three CArG boxes were identified and by Chromatin Imunoprecipitation experiments, we have showed that the ovule identity proteins STK and SEP3 bind to the first and third CArG boxes. We have performed in vivo and in vitro experiments showing that the STK-SEP3 complex is needed to form short-range loops in VDD promoter. For years evidences based on in vitro biochemical assays and yeast experiments shown that MADS box proteins form multimeric complexes. New evidences for the quartet-floral model were obtained, analyzing the activation of VDD promoter by STK-SEP3 multimeric complex. Least but not the last, I have also analyzed the interaction of ARABIDOPSIS BSISTER (ABS) with STK, showing that they have a function in the regulation of the endothelium development, the inner most integument layer of the mature ovule that we demonstrated to be required to the double fertilization process

Quantum computation by quantum-like systems

Using a quantumlike description for light propagation in nonhomogeneous optical fibers, quantum information processing can be implemented by optical means. Quantum-like bits (qulbits) are associated to light modes in the optical fiber and quantum gates to segments of the fiber providing an unitary transformation of the mode structure along a space direction. Simulation of nonlinear quantum effects is also discussed.Comment: 12 pages, Late

Disease processes identified in road killed wild carnivores

Só está disponível o resumoDisease processes identified in road killed wild carnivores

Parents, children and the porous boundaries of the sexual family in law and popular culture

This article focuses on a perceived ideological overlap between popular cultural and judicial treatments of sex and conjugality that contributes to a discursive construction of parenthood and parenting. The author perceives that in both legal and popular cultural texts, there is a sense in which notions of ‘natural’ childhood are discursively constituted as being put at risk by those who reproduce outside of dominant sexual norms, and that signs of normative sexuality (typically in the form of heterosexual coupling) may be treated as a sign of safety. These ideas are rooted in ancient associations between fertility, sexuality and femininity that can also be traced in the historical development of the English language. With the help of commentators such as Martha Fineman, the article situates parents and children within a discourse of family which prioritises conjugality, with consequences for the ways in which the internal and external boundaries of families are delineated

Renal lesions in deer (Cervus elaphus) - Mycobacterium avium subsp. paratuberculosis involvelment

Renal lesions in deer (Cervus elaphus) - Mycobacterium avium subsp. paratuberculosis involvelment

Epidemic processes with immunization

We study a model of directed percolation (DP) with immunization, i.e. with different probabilities for the first infection and subsequent infections. The immunization effect leads to an additional non-Markovian term in the corresponding field theoretical action. We consider immunization as a small perturbation around the DP fixed point in d<6, where the non-Markovian term is relevant. The immunization causes the system to be driven away from the neighbourhood of the DP critical point. In order to investigate the dynamical critical behaviour of the model, we consider the limits of low and high first infection rate, while the second infection rate remains constant at the DP critical value. Scaling arguments are applied to obtain an expression for the survival probability in both limits. The corresponding exponents are written in terms of the critical exponents for ordinary DP and DP with a wall. We find that the survival probability does not obey a power law behaviour, decaying instead as a stretched exponential in the low first infection probability limit and to a constant in the high first infection probability limit. The theoretical predictions are confirmed by optimized numerical simulations in 1+1 dimensions.Comment: 12 pages, 11 figures. v.2: minor correction

Phase transition and selection in a four-species cyclic Lotka-Volterra model

We study a four species ecological system with cyclic dominance whose individuals are distributed on a square lattice. Randomly chosen individuals migrate to one of the neighboring sites if it is empty or invade this site if occupied by their prey. The cyclic dominance maintains the coexistence of all the four species if the concentration of vacant sites is lower than a threshold value. Above the treshold, a symmetry breaking ordering occurs via growing domains containing only two neutral species inside. These two neutral species can protect each other from the external invaders (predators) and extend their common territory. According to our Monte Carlo simulations the observed phase transition is equivalent to those found in spreading models with two equivalent absorbing states although the present model has continuous sets of absorbing states with different portions of the two neutral species. The selection mechanism yielding symmetric phases is related to the domain growth process whith wide boundaries where the four species coexist.Comment: 4 pages, 5 figure