Decidability of Divergence for Catalytic P Systems

P systems are a biologically inspired model introduced by Gheorghe P¸aun with the aim of representing the structure and the functioning of the cell. Since their introduction, several variants of P systems have been proposed and explored. We concentrate on the class of catalytic P systems without priorities associated to the rules. We show that the divergence problem (i.e., checking for the existence of an infinite computation) is decidable in such a class of P systems. As a corollary, we obtain an alternative proof of the nonuniversality of deterministic catalytic P systems, an open problem recently solved by Ibarra and Yen

Some Notes on (Mem)Brane Computation

Membrane Computing and Brane Calculi are two recent computational paradigms in the framework of Natural Computing. They are based on the study of the structure and functioning of living cells as living organisms able to process and generate information. In this paper we give a short introduction to both areas and point out some open research lines.Ministerio de Educación y Ciencia TIN2005-09345-C04-01Junta de Andalucía TIC-58

A Case Study in (Mem)Brane Computation: Generating Squares of Natural Numbers

The aim of this paper is to start an investigation and a comparison of the expressiveness of the two most relevant formalisms inspired by membranes interactions, namely, P systems and Brane Calculi. We compare the two formalisms with respect to their ability to act as generator devices. In particular, we show different ways of generating the set L = {n2 | n ≥ 1} in P systems and in Brane Calculi.Ministerio de Educación y Ciencia TIN2005-09345-C03-01Junta de Andalucía TIC-58

Decidability properties for fragments of CHR

We study the decidability of termination for two CHR dialects which, similarly to the Datalog like languages, are defined by using a signature which does not allow function symbols (of arity >0). Both languages allow the use of the = built-in in the body of rules, thus are built on a host language that supports unification. However each imposes one further restriction. The first CHR dialect allows only range-restricted rules, that is, it does not allow the use of variables in the body or in the guard of a rule if they do not appear in the head. We show that the existence of an infinite computation is decidable for this dialect. The second dialect instead limits the number of atoms in the head of rules to one. We prove that in this case, the existence of a terminating computation is decidable. These results show that both dialects are strictly less expressive than Turing Machines. It is worth noting that the language (without function symbols) without these restrictions is as expressive as Turing Machines

A Case Study in (Mem)Brane Computation: Generating {n2 | n 1}

The aim of this paper is to start an investigation and a comparison of the expressiveness of the two most relevant formalisms inspired by membranes interactions, namely, P systems and Brane Calculi. We compare the two formalisms w.r.t. their ability to act as language generators. In particular, we show different ways of generating the set L = {n2 | n 1} in P systems and in Brane Calculi.Ministerio de Educación y Ciencia TIC2002-04220-C03-0

Polysaccharide-synthesizing Glycosyltransferases and Carbohydrate Binding Modules: the case of Starch Synthase III

Glycosyltransferases (GTs) are a ubiquitous group of enzymes that catalyze the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming glycosidic bonds. Nucleotide-sugars, lipid phosphate sugars and phosphate sugars can act as activated donor molecules while acceptor substrates involve carbohydrates, proteins, lipids, DNA and also, numerous small molecules (i. e. antibiotics, flavonols, steroids). GTs enzyme families are very ancient. They are founded in all the three domains of life and display three different folds (named GT-A, GTB and GT-C) which are a variant of a common α/β scaffold. In addition, several GTs contain an associated non-catalytic carbohydrate binding module (CBM) that could be critical for enzyme activity.This work reviews the current knowledge on the GTs structures and functions and highlights those enzymes that contain CBMs, particularly starch binding domains (SBDs). In addition, we also focus on A. thaliana starch synthase III enzyme, from the GT-5 family. This protein has a GT-B fold, and contains in its N-terminal region three in tandem SBDs, which are essential for the regulation of enzyme activity.Fil: Gomez Casati, Diego Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad Nacional de Rosario; ArgentinaFil: Martín, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad Nacional de Rosario; ArgentinaFil: Busi, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad Nacional de Rosario; Argentin

Dependencies and Simultaneity in Membrane Systems

Membrane system computations proceed in a synchronous fashion: at each step all the applicable rules are actually applied. Hence each step depends on the previous one. This coarse view can be refined by looking at the dependencies among rule occurrences, by recording, for an object, which was the a rule that produced it and subsequently (in a later step), which was the a rule that consumed it. In this paper we propose a way to look also at the other main ingredient in membrane system computations, namely the simultaneity in the rule applications. This is achieved using zero-safe nets that allows to synchronize transitions, i.e., rule occurrences. Zero-safe nets can be unfolded into occurrence nets in a classical way, and to this unfolding an event structure can be associated. The capability of capturing simultaneity of zero-safe nets is transferred on the level of event structure by adding a way to express which events occur simultaneously

Temporally resolved second-order photon correlations of exciton-polariton Bose-Einstein condensate formation

Second-order time correlation measurements with a temporal resolution better than 3 ps were performed on a CdTe microcavity where spontaneous Bose-Einstein condensation is observed. After the laser pulse, the nonresonantly excited thermal polariton population relaxes into a coherent polariton condensate. Photon statistics of the light emitted by the microcavity evidences a clear phase transition from the thermal state to a coherent state, which occurs within 3.2 ps after the onset of stimulated scattering. Following this very fast transition, we show that the emission possesses a very high coherence that persists for more than 100 ps after the build-up of the condensate.Comment: 4 pages, 3 figure

Metabolomics in plants and humans: Applications in the prevention and diagnosis of diseases.

In the recent years, there has been an increase in the number of metabolomic approaches used, in parallel with proteomic and functional genomic studies. The wide variety of chemical types of metabolites available has also accelerated the use of different techniques in the investigation of the metabolome. At present, metabolomics is applied to investigate several human diseases, toimprove their diagnosis and prevention, and to design better therapeutic strategies. In addition,metabolomic studies are also being carried out in areas such as toxicology and pharmacology, crop breeding, and plant biotechnology. In this review, we emphasizethe use and application of metabolomics in human diseases and plant research to improve human health.Fil: Gomez Casati, Diego Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); ArgentinaFil: Zanor, María Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Busi, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad Nacional de San Martín; Argentin

Cochlear Implant Outcomes and Genetic Mutations in Children with Ear and Brain Anomalies

Background. Specific clinical conditions could compromise cochlear implantation outcomes and drastically reduce the chance of an acceptable development of perceptual and linguistic capabilities. These conditions should certainly include the presence of inner ear malformations or brain abnormalities. The aims of this work were to study the diagnostic value of high resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in children with sensorineural hearing loss who were candidates for cochlear implants and to analyse the anatomic abnormalities of the ear and brain in patients who underwent cochlear implantation. We also analysed the effects of ear malformations and brain anomalies on the CI outcomes, speculating on their potential role in the management of language developmental disorders. Methods. The present study is a retrospective observational review of cochlear implant outcomes among hearing-impaired children who presented ear and/or brain anomalies at neuroimaging investigations with MRI and HRCT. Furthermore, genetic results from molecular genetic investigations (GJB2/GJB6 and, additionally, in selected cases, SLC26A4 or mitochondrial-DNA mutations) on this study group were herein described. Longitudinal and cross-sectional analysis was conducted using statistical tests. Results. Between January 1, 1996 and April 1, 2012, at the ENT-Audiology Department of the University Hospital of Ferrara, 620 cochlear implantations were performed. There were 426 implanted children at the time of the present study (who were <18 years). Among these, 143 patients (64 females and 79 males) presented ear and/or brain anomalies/lesions/malformations at neuroimaging investigations with MRI and HRCT. The age of the main study group (143 implanted children) ranged from 9 months and 16 years (average = 4.4; median = 3.0). Conclusions. Good outcomes with cochlear implants are possible in patients who present with inner ear or brain abnormalities, even if central nervous system anomalies represent a negative prognostic factor that is made worse by the concomitant presence of cochlear malformations. Common cavity and stenosis of the internal auditory canal (less than 2 mm) are negative prognostic factors even if brain lesions are absent