Language Constructs for Non-Well-Founded Computation

Recursive functions defined on a coalgebraic datatype C may not converge if there are cycles in the input, that is, if the input object is not well-founded. Even so, there is often a useful solution; for example, the free variables of an infinitary λ-term, or the expected running time of a finite-state probabilistic protocol. Theoretical models of recursion schemes have been well studied

Sound and complete axiomatizations of coalgebraic language equivalence

Coalgebras provide a uniform framework to study dynamical systems, including several types of automata. In this paper, we make use of the coalgebraic view on systems to investigate, in a uniform way, under which conditions calculi that are sound and complete with respect to behavioral equivalence can be extended to a coarser coalgebraic language equivalence, which arises from a generalised powerset construction that determinises coalgebras. We show that soundness and completeness are established by proving that expressions modulo axioms of a calculus form the rational fixpoint of the given type functor. Our main result is that the rational fixpoint of the functor $FT$, where $T$ is a monad describing the branching of the systems (e.g. non-determinism, weights, probability etc.), has as a quotient the rational fixpoint of the "determinised" type functor $\bar F$, a lifting of $F$ to the category of $T$-algebras. We apply our framework to the concrete example of weighted automata, for which we present a new sound and complete calculus for weighted language equivalence. As a special case, we obtain non-deterministic automata, where we recover Rabinovich's sound and complete calculus for language equivalence.Comment: Corrected version of published journal articl

Antimicrobial peptide combinations against Pseudomonas aeruginosa and Staphylococcus aureus

Today, we are facing a major challenge regarding the development of new strategies and the discovery of new compounds with effective antimicrobial outcomes. The emergence of resistance is a preoccupant health threat and conventional antibiotics are being rendered ineffective. Researchers are now focusing in alternatives, such as the discovery of new antimicrobials with different modes of action, and the combination of agents potentiating their efficacy. AMPs are an example of new antimicrobials with promising applications, since they have different and sometimes unspecific mechanisms of action compared to traditional antibiotics, reducing the chance of acquired resistance. This work analyses AMP combinations against major pathogenic bacteria, Pseudomonas aeruginosa and Staphylococcus aureus, currently great contributors for resistance development and responsible for chronic infections, such as cystic fibrosis pneumonia. We present a screening of combinations of colistin with temporin A, citropin 1.1, tachyplesin I, lactoferricin B, magainin II and G10KHc, against these pathogens, including references and clinical isolate strains. Results show that most combinations have synergetic activities, which means that AMP combinations should be a viable way for the development of new antimicrobial treatments, thus reducing their toxicity and side effects, while maintaining efficacy. Some of the best combinations will be tested on biofilms of these bacteria, in order to test their prophylactic and therapeutic action against this different and more resilient mode of growth

Response surface optimization of the culture medium for production of elastin-like polymers by E. coli

ASTM program POCI 2010 (project POCI/CTM/57177/2004) suported by FEDER and FCTElastin-Like Polymers (ELP`s), a family of proteins based on repetitive pentapeptide sequences known by their smart and extremely biocompatible behavior (1, 2), are of great interest to our research group. Ongoing work using E. coli as the expression system, strongly suggests that the biomass and polymer production are closely related. The Response Surface Methodology (RSM) is a collection of mathematical and statistical techniques useful for the modeling and analysis of problems, in which a response of interest is influenced by several variables and the objective is to optimize this response, in a suitable set of experiments (3). This strategy was employed in order to improve the production of both, biomass and ELP`s, in an auto induction medium previously designed by us (adapted from Terrific Broth and Phosphate Buffer Glycerol). The nutrients yeast extract, lactose and glycerol were the factors subjected to this statistical treatment. Knowing that glycerol and lactose are, respectively, sub-products of biodiesel production and dairy industry, the use of these compounds is highly favorable for the design of a sustainable scale-up procedure. On the other hand, yeast extract was selected in order to maximize the final yield due to it`s described importance in the boost of production. The validation of the model obtained was achieved and allowed the optimization of biomass levels.info:eu-repo/semantics/publishedVersio

The mental health of elite athletes: A narrative systematic review

BACKGROUND: The physical impacts of elite sport participation have been well documented; however, there is comparatively less research on the mental health and psychological wellbeing of elite athletes. OBJECTIVE: This review appraises the evidence base regarding the mental health and wellbeing of elite-level athletes, including the incidence and/or nature of mental ill-health and substance use. METHODS: A systematic search of the PubMed, EMBASE, SPORTDiscus, PsycINFO, Cochrane and Google Scholar databases, up to and including May 2015, was conducted. RESULTS: The search yielded a total of 2279 records. Following double screening, 60 studies were included. The findings suggested that elite athletes experience a broadly comparable risk of high-prevalence mental disorders (i.e. anxiety, depression) relative to the general population. Evidence regarding other mental health domains (i.e. eating disorders, substance use, stress and coping) is less consistent. These results are prefaced, however, by the outcome of the quality assessment of the included studies, which demonstrated that relatively few studies (25 %) were well reported or methodologically rigorous. Furthermore, there is a lack of intervention-based research on this topic. CONCLUSION: The evidence base regarding the mental health and wellbeing of elite athletes is limited by a paucity of high-quality, systematic studies. Nonetheless, the research demonstrates that this population is vulnerable to a range of mental health problems (including substance misuse), which may be related to both sporting factors (e.g. injury, overtraining and burnout) and non-sporting factors. More high-quality epidemiological and intervention studies are needed to inform optimal strategies to identify and respond to player mental health needs

History-sensitive versus future-sensitive approaches to security in distributed systems

We consider the use of aspect-oriented techniques as a flexible way to deal with security policies in distributed systems. Recent work suggests to use aspects for analysing the future behaviour of programs and to make access control decisions based on this; this gives the flavour of dealing with information flow rather than mere access control. We show in this paper that it is beneficial to augment this approach with history-based components as is the traditional approach in reference monitor-based approaches to mandatory access control. Our developments are performed in an aspect-oriented coordination language aiming to describe the Bell-LaPadula policy as elegantly as possible. Furthermore, the resulting language has the capability of combining both history- and future-sensitive policies, providing even more flexibility and power.Comment: In Proceedings ICE 2010, arXiv:1010.530

A dual-function SNF2 protein drives chromatid resolution and nascent transcripts removal in mitosis

Mitotic chromatin is largely assumed incompatible with transcription due to changes in the transcription machinery and chromosome architecture. However, the mechanisms of mitotic transcriptional inactivation and their interplay with chromosome assembly remain largely unknown. By monitoring ongoing transcription in Drosophila early embryos, we reveal that eviction of nascent mRNAs from mitotic chromatin occurs after substantial chromosome compaction and is not promoted by condensin I. Instead, we show that the timely removal of transcripts from mitotic chromatin is driven by the SNF2 helicase-like protein Lodestar (Lds), identified here as a modulator of sister chromatid cohesion defects. In addition to the eviction of nascent transcripts, we uncover that Lds cooperates with Topoisomerase 2 to ensure efficient sister chromatid resolution and mitotic fidelity. We conclude that the removal of nascent transcripts upon mitotic entry is not a passive consequence of cell cycle progression and/or chromosome compaction but occurs via dedicated mechanisms with functional parallelisms to sister chromatid resolution.info:eu-repo/semantics/publishedVersio

Crosstalk between the calcineurin and cell wall integrity pathways prevents chitin overexpression in Candida albicans

Funding Information: We thank Carol Munro for helpful discussions during the research, Raif Yuecel, Elizabeth Adams, Linda Duncan, Barry Lewis and Kimberley Sim for assistance with FACS at Aberdeen Cytometry Core Facility, and Yang Meng and Dominique Sanglard with help in construction of mutants. We also thank Linghuo Jiang, David Soll, Jes?s Pla, Jan Quinn, Terry Roemer and Joseph Heitman for mutant strains. N.A.R.G. acknowledges support from the Wellcome Trust [Senior Investigator (101873/Z/13/Z), Collaborative (200208/A/15/Z and 215599/Z/19/Z) and Strategic (097377/Z11/Z) Awards] and from the Medical Research Council Centre for Medical Mycology (MR/N006364/2). This work was also supported by a Marie Curie FP7-PEOPLE-ITN-2008 grant (MB004 RGE0655 ARIADNE) and by a Wellcome Trust project grant (086827). Open access funding provided by University of Exeter. Deposited in PMC for immediate release.Peer reviewedPublisher PD

ASELL : the advancing science by enhancing learning in the laboratory project

Most science educators and researchers will agree that the laboratory experience ranks as a major factor that influences students’ attitudes to their science courses. Consequently, good laboratory programs should play a major role in influencing student learning and performance. The laboratory program can be pivotal in defining a student\u27s experience in the sciences, and if done poorly, can be a major contributing factor in causing disengagement from the subject area. The challenge remains to provide students with laboratory activities that are relevant, engaging and offer effective learning opportunities