A Geometric Algorithm to construct new solitons in the O(3) Nonlinear Sigma Model

The O(3) nonlinear sigma model with boundary, in dimension two, is considered. An algorithm to determine all its soliton solutions that preserve a rotational symmetry in the boundary is exhibited. This nonlinear problem is reduced to that of clamped elastica in a hyperbolic plane. These solutions carry topological charges that can be holographically determined from the boundary conditions. As a limiting case, we give a wide family of new soliton solutions in the free O(3) nonlinear sigma model.Comment: 10 page

Convergence Rates of Approximation by Translates

In this paper we consider the problem of approximating a function belonging to some funtion space Φ by a linear comination of n translates of a given function G. Ussing a lemma by Jones (1990) and Barron (1991) we show that it is possible to define function spaces and functions G for which the rate of convergence to zero of the erro is 0(1/n) in any number of dimensions. The apparent avoidance of the "curse of dimensionality" is due to the fact that these function spaces are more and more constrained as the dimension increases. Examples include spaces of the Sobolev tpe, in which the number of weak derivatives is required to be larger than the number of dimensions. We give results both for approximation in the L2 norm and in the Lc norm. The interesting feature of these results is that, thanks to the constructive nature of Jones" and Barron"s lemma, an iterative procedure is defined that can achieve this rate

The neural mechanisms for the recognition of face identity in humans

Every day we encounter dozens of people, and in order to interact with them appropriately we need to recognize their identity. The face is a crucial source of information to recognize a person’s identity. However, recognizing the identity of a face is challenging because it requires distinguishing between very similar images (e.g., the front views of two different faces) while categorizing very different images (e.g., a front view and a profile) as the same person. Neuroimaging has the whole-brain coverage needed to investigate where representations of face identity are encoded, but it is limited in terms of spatial and temporal resolution. In this article, we review recent neuroimaging research that attempted to investigate the representation of face identity, the challenges it faces, and the proposed solutions, to conclude that given the current state of the evidence the right anterior temporal lobe is the most promising candidate region for the representation of face identity

Combining the conservation of biodiversity with the provision of ecosystem services in urban green infrastructure planning. Critical features arising from a case study in the metropolitan area of Rome

A large number of green infrastructure (GI) projects have recently been proposed, planned and implemented in European cities following the adoption of the GI strategy by the EU Commission in 2013. Although this policy tool is closely related to biodiversity conservation targets, some doubts have arisen as regards the ability of current urban GI to provide beneficial effects not only for human societies but also for the ecological systems that host them. The aim of this work is to review the features that should be considered critical when searching for solutions that simultaneously support biodiversity and guarantee the provision of ecosystem services (ES) in urban areas. Starting from a case study in the metropolitan area of Rome, we highlight the role of urban trees and forests as proxies for overall biodiversity and as main ecosystem service providers. We look beyond the individual functional features of plant species and vegetation communities to promote the biogeographic representativity, ecological coherence and landscape connectivity of new or restored GI elements

Molecular characterization and functional expression of flavonol 6-hydroxylase

BACKGROUND: Flavonoids, one of the major groups of secondary metabolites, play important roles in the physiology, ecology and defence of plants. Their wide range of activities is the result of their structural diversity that encompasses a variety of functional group substitutions including hydroxylations. The aromatic hydroxylation at position 6 of flavonols is of particular interest, since it is catalyzed by a 2-oxoglutarate-dependent dioxygenase (ODD), rather than a cytochrome P450-dependent monooxygenase. ODDs catalyze a variety of enzymatic reactions implicated in secondary metabolite biosynthesis. RESULTS: A cDNA fragment encoding an ODD involved in the 6-hydroxylation of partially methylated flavonols, flavonol 6-hydroxylase (F6H), was isolated and characterized from Chrysosplenium americanum using internal peptide sequence information obtained from the native plant protein. This novel clone was functionally expressed in both prokaryotic and eukaryotic expression systems and exhibited ODD activity. The cofactor and cosubstrate requirements of the recombinant proteins are typical for ODDs, and the recombinant enzymes utilize 3,7,4'-trimethylquercetin as the preferred substrate. The genomic region encoding this enzyme possesses two introns at conserved locations for this class of enzymes and is present as a single copy in the C. americanum genome. CONCLUSIONS: Recombinant F6H has been functionally expressed and characterized at the molecular level. The results demonstrate that its cofactor dependence, physicochemical characteristics and substrate preference compare well with the native enzyme. The N-terminal region of this protein is believed to play a significant role in catalysis and may explain the difference in the position specificity of the 6-hydroxylation reaction

Biochemical and molecular characterization of a novel dioxygenase, flavonol 6- hydroxylase, involved in flavonol biosynthesis from chrysosplenium americanum

Plants synthesize a vast array of natural products, collectively known as secondary metabolites, of which flavonoids constitute an important group. Flavonoid compounds are ubiquitous in Nature and play important roles in plant physiology, development and the plant's interaction with its environment. They contribute to flower color, ultraviolet protection, cell signalling and defence against plant pathogen attack, in addition to their potential benefits to mammalian organisms. In most cases, structure-activity relationships have been observed and, therefore, modification of the substitution pattern of certain compounds may enhance the quality and/or performance of plants through metabolic engineering. Chrysosplenium americanum , a semi-aquatic weed, elaborates a variety of highly methylated flavonoids that are synthesized by regio-specific enzymes, and are believed to protect the plant against microbial attack. Several of the substitution reactions involved in the proposed pathway of their biosynthesis previously have been elucidated. One of the enzymes involved at the branchpoint of this pathway, the flavonol 6-hydroxylase (F6H) has been the primary focus of this research. The novelty of this enzyme lies in the fact that it is the only reported {460}-ketoglutarate-dependent dioxygenase that introduces a phenolic hydroxyl group on the flavonoid ring; more specifically at position 6 of trimethylquercetin, which is subsequently methylated. The dioxygenase nature of the enzyme has been established and the hydroxylation reaction has been characterized at the biochemical level, including its physicochemical properties and kinetic mechanism. The F6H protein was purified to near homogeneity in its functional state, through an original strategy involving conventional chromatography and affinity columns, and partial amino acid sequences of the purified protein were obtained. The microsequence information obtained was used as a guide in primer design for the cloning of the F6H cDNA from a C. americanum library that was screened using a PCR-based strategy. A cDNA fragment was subsequently isolated and cloned and its gene product was characterized at the biochemical and molecular levels. The protein predicted from the F6H cDNA clone contains the conserved motifs for this class of enzymes, as well as the microsequences obtained from the purified plant protein. In addition, the clone exhibits F6H activity when expressed in both prokaryotic and eukaryotic expression systems. At the molecular level, F6H is present as a single copy in the C. americanum genome, and contains two introns of approximate length and position comparable to a particular class of dioxygenases, suggesting an evolutionary relationship. (Abstract shortened by UMI.

Differential Activity for Animals and Manipulable Objects in the Anterior Temporal Lobes

Neuropsychological evidence has highlighted the role of the anterior temporal lobes in the processing of conceptual knowledge. That putative role is only beginning to be investigated with fMRI as methodological advances are able to compensate for well-known susceptibility artifacts that affect the quality of the BOLD signal. In this article, we described differential BOLD activation for pictures of animals and manipulable objects in the anterior temporal lobes, consistent with previous neuropsychological findings. Furthermore, we found that the pattern of BOLD signal in the anterior temporal lobes is qualitatively different from that in the fusiform gyri. The latter regions are activated to different extents but always above baseline by images of the preferred and of the nonpreferred categories, whereas the anterior temporal lobes tend to be activated by images of the preferred category and deactivated (BOLD below baseline) by images of the nonpreferred category. In our experimental design, we also manipulated the decision that participants made over stimuli from the different semantic categories. We found that in the right temporal pole, the BOLD signal shows some evidence of being modulated by the task that participants were asked to perform, whereas BOLD activity in more posterior regions (e.g., the fusiform gyri) is not modulated by the task. These results reconcile the fMRI literature with the neuropsychological findings of deficits for animals after damage to the right temporal pole and suggest that anterior and posterior regions within the temporal lobes involved in object processing perform qualitatively different computations.Psycholog

A Sobolev Poincar\'e type inequality for integral varifolds

In this work a local inequality is provided which bounds the distance of an integral varifold from a multivalued plane (height) by its tilt and mean curvature. The bounds obtained for the exponents of the Lebesgue spaces involved are shown to be sharp.Comment: v1: 27 pages, no figures; v2: replaced citations of the author's dissertation by proofs, material of sections 1 and 3 reorganised, slightly more general results in section 2, some remarks, some discussion and some references added, 40 pages, no figure

Vivere il qui e ora: le arti performative che fanno parte dei beni culturali immateriali

Twenty years after the establishment of intangible cultural heritage, we want to take report of what has been done to protect these heritage and the difficulties encountered. Starting from the genesis of the acknowledgement of the importance of these heritage and the transposition by the various States of the UNESCO 2003 legislation, attention will be focused on the Italian situation with particular reference to the performing arts, in particular the dances; while in other countries they have found space and recognition, in Italy they struggle to find their definition. The dance, not characterized by tangibility, lives in the hic et nunc, the here and now, and this ephemerality creates many problems in terms of preservation and conservation. The challenges in the matter are different, it is easy to incur negative results such as freezing of traditions or "commercial" upheavals. There are several years that we talk about the nomination of some traditional dances, which would require special attention as their origins are in danger and/ or are at risk of distortion (e.g. pizzica pizzica), but still nothing has been done. This example will allow us to explore the difficulties posed by the performing arts, the new challenges and what has already been achieved in this field

Study Of Covalent And Non-Covalent Interactions In Ternary Systems Involving: Metal/DNA-RNA/Protein, Where Metal = Platinum(II), Palladium(II)

Ternary systems comprising DNA/RNA, proteins and one (or more) metal ion are generating increased interest due to its biological relevance. The knowledge gained from the study of these systems could provide important clues regarding the precise mechanism for transcription factors, repair proteins and metal complexes with anti-tumoral/anti-viral activities.The interactions occurring among the components of these ternary systems can be broadly grouped into covalent and non-covalent. The first kind of interactions can lead to the irreversible transformation of the components in the system, while the second is thought to be reversible leading to transient states and fluxionality. Both kinds of interaction are generally present in living systems, complementing the function of each other.Monofunetional Platinum-nucleobase complexes (MPNs) are synthesized via substitution of a chloride ligand by a nucleobase in platinum complexes with trans geometry. MPNs are particularly interesting for the study of ternary systems since they mimic the first step in the formation of a platinum-DNA adduct and their interaction with aminoacids/proteins provide a good first approach for more complex systems.The presence of the nucleobase as a ligand, significantly modifies the biological activity of these complexes by reducing its cytotoxicity and generating a promising anti-viral activity, especially against HIV-1 virus. The specific role of the nucleobase ligand on these complexes as a non-covalent motif, important for protein recognition, was explored in models involving tryptophan/N-acetyl tryptophan and a small protein domain called zinc finger, containing also a tryptophan residue.The coordination of the nucleobase to a metal ion such as Pt(II) or Pd(II) was found to increase its π-stacking interaction towards aromatic residues in proteins, specifically tryptophan. The enhancing effect was found to depend on the nature of the metal ion, nature of nucleobase and size/complexity of the protein model. Furthermore, DFT studies revealed an important change in the energy for the lowest unoccupied molecular orbital (LUMO) in the coordinated nucleobases, which could place this orbital in an favored position to interact with the highest occupied molecular orbital (HOMO) in the tryptophan residue. Results from calculations showed a good correlation with experimental evidence and could indicate an important role for the frontier molecular orbitals (HOMO/LUMO) of the species involved in the π-stacking interaction.This study was extended to a zinc finger domain from an essential protein in HIV-1 virus, i.e. nucleocapsid protein NCp7. Findings showed that the nucleobase ligand in addition to modulate hydrolysis and reaction rates for MPNs can also be responsible for an initial non-covalent recognition towards a specific protein. This initial recognition has been proposed as the first stage in a two-step mechanism of action for these platinum complexes that ultimately can lead to zinc ejection from the zinc finger domain in the viral NCp7. The significance of the data presented show that is possible to modulate the ligand coordination sphere in metal complexes to can result in great differences in terms of biological effects.The novel chemistry derived from DNA adducts with platinum complexes with a trans geometry was also explored in silico. The molecular dynamics of two free DNA 20-mer is compared with the corresponding metallated-adducts, namely monofunctional, 1,2-bifunctional interstrand and 1,3-bifunctional intrastrand. The differences in terms of structure and energy are compared for these systems, in general the monofunctional adduct exhibited the most interesting feature in terms of structural change in the DNA double strand causing the destacking of the metallated nucleobase. Bifunctional adducts exhibited loss of Watson-crick bonds and localized change in sugar puckering. These results showed that important differences can be found for platinated DNA even at short simulation times \u3c 1 ns