Stream Productivity by Outermost Termination

Streams are infinite sequences over a given data type. A stream specification is a set of equations intended to define a stream. A core property is productivity: unfolding the equations produces the intended stream in the limit. In this paper we show that productivity is equivalent to termination with respect to the balanced outermost strategy of a TRS obtained by adding an additional rule. For specifications not involving branching symbols balancedness is obtained for free, by which tools for proving outermost termination can be used to prove productivity fully automatically

A Machine Checked Model of Idempotent MGU Axioms For Lists of Equational Constraints

We present formalized proofs verifying that the first-order unification algorithm defined over lists of satisfiable constraints generates a most general unifier (MGU), which also happens to be idempotent. All of our proofs have been formalized in the Coq theorem prover. Our proofs show that finite maps produced by the unification algorithm provide a model of the axioms characterizing idempotent MGUs of lists of constraints. The axioms that serve as the basis for our verification are derived from a standard set by extending them to lists of constraints. For us, constraints are equalities between terms in the language of simple types. Substitutions are formally modeled as finite maps using the Coq library Coq.FSets.FMapInterface. Coq's method of functional induction is the main proof technique used in proving many of the axioms.Comment: In Proceedings UNIF 2010, arXiv:1012.455

Nominal Henkin Semantics: simply-typed lambda-calculus models in nominal sets

We investigate a class of nominal algebraic Henkin-style models for the simply typed lambda-calculus in which variables map to names in the denotation and lambda-abstraction maps to a (non-functional) name-abstraction operation. The resulting denotations are smaller and better-behaved, in ways we make precise, than functional valuation-based models. Using these new models, we then develop a generalisation of \lambda-term syntax enriching them with existential meta-variables, thus yielding a theory of incomplete functions. This incompleteness is orthogonal to the usual notion of incompleteness given by function abstraction and application, and corresponds to holes and incomplete objects.Comment: In Proceedings LFMTP 2011, arXiv:1110.668

Gut microbiota features associated with Campylobacter burden and postnatal linear growth deficits in a Peruvian birth cohort

BACKGROUND: Campylobacter infection is associated with impaired growth of children, even in the absence of symptoms. To examine the underlying mechanisms, we evaluated associations between Campylobacter infection, linear growth, and fecal microbial community features in a prospective birth cohort of 271 children with a high burden of diarrhea and stunting in the Amazonian lowlands of Peru. METHODS: Campylobacter was identified using a broadly reactive, genus-specific enzyme-linked immunosorbent assay. 16S rRNA-based analyses were used to identify bacterial taxa in fecal samples at ages 6, 12, 18, and 24 months (N = 928). Associations between infection, growth, and gut microbial community composition were investigated using multiple linear regression adjusting for within-child correlations, age, and breastfeeding. Indicator species analyses identified taxa specifically associated with Campylobacter burden. RESULTS: Ninety-three percent (251) of children had Campylobacter present in asymptomatic fecal samples during the follow-up period. A 10% increase in the proportion of stools infected was associated with mean reductions of 0.02 length-for-age z scores (LAZ) at 3, 6, and 9 months thereafter (P \u3c .01). We identified 13 bacterial taxa indicative of cumulative Campylobacter burden and 14 taxa significantly associated with high or low burden of enteroaggregative Escherichia coli, norovirus, or Giardia. CONCLUSIONS: Campylobacter infection is common in this cohort and associated with changes in microbial community composition. These results support the notion that disruptions to the fecal microbiota may help explain the observed effects of asymptomatic infections on growth in early life

PORGY: Strategy-Driven Interactive Transformation of Graphs

This paper investigates the use of graph rewriting systems as a modelling tool, and advocates the embedding of such systems in an interactive environment. One important application domain is the modelling of biochemical systems, where states are represented by port graphs and the dynamics is driven by rules and strategies. A graph rewriting tool's capability to interactively explore the features of the rewriting system provides useful insights into possible behaviours of the model and its properties. We describe PORGY, a visual and interactive tool we have developed to model complex systems using port graphs and port graph rewrite rules guided by strategies, and to navigate in the derivation history. We demonstrate via examples some functionalities provided by PORGY.Comment: In Proceedings TERMGRAPH 2011, arXiv:1102.226

Diarrhea as a potential cause and consequence of reduced gut microbial diversity among undernourished children in Peru

BACKGROUND: Detrimental effects of diarrhea on child growth and survival are well documented, but details of the underlying mechanisms remain poorly understood. Recent evidence demonstrates that perturbations to normal development of the gut microbiota in early life may contribute to growth faltering and susceptibility to related childhood diseases. We assessed associations between diarrhea, gut microbiota configuration, and childhood growth in the Peruvian Amazon. METHODS: Growth, diarrhea incidence, illness, pathogen infection, and antibiotic exposure were assessed monthly in a birth cohort of 271 children aged 0-24 months. Gut bacterial diversity and abundances of specific bacterial taxa were quantified by sequencing 16S rRNA genes in fecal samples collected at 6, 12, 18, and 24 months. Linear and generalized linear models were used to determine whether diarrhea was associated with altered microbiota and, in turn, if features of the microbiota were associated with the subsequent risk of diarrhea. RESULTS: Diarrheal frequency, duration, and severity were negatively associated with bacterial diversity and richness (P \u3c .05). Children born stunted (length-for-age z-score [LAZ] ≤ -2) who were also severely stunted (LAZ ≤ -3) at the time of sampling exhibited the greatest degree of diarrhea-associated reductions in bacterial diversity and the slowest recovery of bacterial diversity after episodes of diarrhea. Increased bacterial diversity was predictive of reduced subsequent diarrhea from age 6 to 18 months. CONCLUSIONS: Persistent, severe growth faltering may reduce the gut microbiota\u27s resistance and resilience to diarrhea, leading to greater losses of diversity and longer recovery times. This phenotype, in turn, denotes an increased risk of future diarrheal disease and growth faltering

Assistive technologies to address capabilities of people with dementia: from research to practice

Assistive technologies (AT) became pervasive and virtually present in all our life domains. They can be either an enabler or an obstacle leading to social exclusion. The Fondation Médéric Alzheimer gathered international experts of dementia care, with backgrounds in biomedical, human and social sciences, to analyse how AT can address the capabilities of people with dementia, on the basis of their needs. Discussion covered the unmet needs of people with dementia, the domains of daily life activities where AT can provide help to people with dementia, the enabling and empowering impact of technology to improve their safety and wellbeing, barriers and limits of use, technology assessment, ethical and legal issues. The capability approach (possible freedom) appears particularly relevant in person-centered dementia care and technology development. The focus is not on the solution, rather on what the person can do with it: seeing dementia as disability, with technology as an enabler to promote capabilities of the person, provides a useful framework for both research and practice. This article summarizes how these concepts took momentum in professional practice and public policies in the past fifteen years (2000-2015), discusses current issues in the design, development and economic model of AT for people with dementia, and covers how these technologies are being used and assessed

Eficacia y seguridad de la técnica coplanar en comparación con las técnicas de derotación convencional para la corrección quirúrgica de deformidades de la columna vertebral: una evaluación de tecnología sanitaria en niños, jóvenes y adultos

A health technology assessment (HTA) was carried out to critically analyze the evidence on the efficacy and safety of the surgical correction of spinal deformities using the coplanar technique, compared to the conventional derotation techniques, in children, adolescents and adults. A systematic search of the literature was carried out in the PubMed, Cochrane Library and LILACS databases. In addition, a manual search was carried out in the reference lists of the included studies, on Google and on the websites of specialized societies and groups that produce clinical practice guidelines (CPG) and HTA. In addition, we searched ClinicalTrials.gov and the International Clinical Trial Registry Platform (ICTRP) for clinical trial records in progress or not completed. Five documents were selected for evaluation, including two CPG, a randomized clinical trial, and two observational studies. After a critical evaluation of the evidence, it was concluded that both techniques showed a similar efficacy profile in terms of relevant outcomes such as correction of curvatures in the coronal and sagittal planes, quality of life and surgical time. Likewise, the rates of screw malposition, complications and volume of blood loss did not show significant differences between both techniques. However, the profile of  opportunity cost of the systems that allow the application of the coplanar technique is not favorable in the context of the evaluation, due to its high cost concerning conventional systems.Se realizó una evaluación de tecnología sanitaria (ETS) con el objetivo de analizar críticamente la evidencia sobre la eficacia y seguridad de la corrección quirúrgica de las deformidades de la columna vertebral con el uso de la técnica coplanar, en comparación con la técnica de derotación convencional, en pacientes niños, jóvenes y adultos. Se llevó a cabo una búsqueda sistemática de la evidencia en las bases de datos de PubMed, Cochrane Library y LILACS. Además, se realizó una búsqueda manual en las listas de referencias de los estudios incluidos, así como, en Google y páginas web de sociedades especializadas y grupos que realizan guías de práctica clínica (GPC) y ETS. Adicionalmente, se buscó registros de estudios clínicos en ejecución o aún no terminados en ClinicalTrials.gov y el International Clinical Trial Registry Platform (ICTRP). Se seleccionaron cinco documentos para evaluación, incluyendo dos GPC, un ensayo clínico aleatorizado y dos estudios observacionales. Luego de la evaluación crítica de la evidencia, se concluyó que, ambas técnicas mostraron un perfil de eficacia similar en cuanto a desenlaces de relevancia como corrección de curvaturas en el plano coronal, sagital, calidad de vida y tiempo quirúrgico. Asimismo, las tasas de malposición de tornillos, complicaciones y volumen de pérdida sanguínea no mostraron diferencias significativas entre ambas técnicas. Sin embargo, el perfil de costo de oportunidad de los sistemas que permiten la aplicación de la técnica coplanar no es favorable en el contexto de la evaluación, debido a su alto costo en relación con los sistemas convencionales

Elaboración de fichas técnicas de dispositivos médicos en el marco de las evaluaciones de tecnologías sanitarias durante la pandemia por COVID-19: Una revisión de la situación a nivel mundial y reporte de la experiencia peruana

Background: Given the health emergency caused by COVID-19, the need for the use of medical devices was particularly relevant. Methodology: A non-systematic literature search was conducted to identify documents that address topics related to the development, implementation, evaluation and/or characteristics of technical datasheets for medical devices. In addition, the SAP System was reviewed for the collection and analysis of data related to pre-pandemic (2000-2019) and in-pandemic (2020-2021) procurement. Evidence: At the global level, the experiences of WHO, ECRI Institute and INAHTA were described. At the Latin American level, experiences were found in Ecuador, Colombia, Argentina, Brazil, Mexico and Panama. Finally, at the Peruvian level, the experience of EsSalud was reported, showing that, from March 6, 2020 to May 21, 2021, 47 technical specifications were prepared for medical devices, of which 41 had purchase records, and of these, 13 correspond to biomedical and complementary equipment. We prioritized the reporting of consumption information (expressed in quantities purchased) for three devices: compact pulse oximeter, high-flow oxygen therapy equipment and the oxygen concentrator (10 L/min). Conclusion: The preparation of technical sheets considers the best scientific evidence available, as well as the technical-technological aspects of the medical device. In EsSalud, its preparation has allowed the incorporation of a significant quantity and variety of biomedical equipment for the treatment of COVID-19, in addition they have been made available with recommendations for their clinical use based on the scientific evidence analyzed.Introducción: Ante la situación de emergencia sanitaria por la COVID-19, la necesidad de uso de dispositivos médicos tuvo especial relevancia. Metodología: Se realizó una búsqueda no sistemática de la literatura dirigida a la identificación de documentos que aborden tópicos relacionados al desarrollo, implementación, evaluación y/o características de fichas técnicas de dispositivos médicos. Así mismo, se revisó el Sistema SAP para la obtención y análisis de los datos relacionados a las compras antes de pandemia (2000-2019) y durante pandemia (2020-2021). Contenido: A nivel mundial, se describieron las experiencias de la OMS, Instituto ECRI e INAHTA. A nivel de Latinoamérica, se encontraron experiencias en Ecuador, Colombia, Argentina, Brasil, México y Panamá. Finalmente, a nivel Perú, se reportó la experiencia de EsSalud, evidenciándose que, del 6 de marzo de 2020 al 21 de mayo de 2021, se elaboraron 47 fichas técnicas de dispositivos médicos, de las cuales 41 figuraban con registros de compras, y de estos, 13 corresponden a equipos biomédicos y complementarios. Priorizamos el reporte de información del consumo (expresado en cantidades adquiridas) de tres dispositivos: pulsioxímetro compacto, equipo de oxigenoterapia de alto flujo y concentrador de oxígeno de 10 L/minuto. Conclusión: La elaboración de fichas técnicas considera la mejor evidencia científica disponible, así como los aspectos técnicos-tecnológicos propios del dispositivo médico. En EsSalud, su elaboración ha permitido incorporar una importante cantidad y variedad de equipos biomédicos para el tratamiento de COVID-19, ademas han sido puestos a disposición con recomendaciones de su uso clínico sustentadas en la evidencia científica analizada

A Weakened Transcriptional Enhancer Yields Variegated Gene Expression

Identical genes in the same cellular environment are sometimes expressed differently. In some cases, including the immunoglobulin heavy chain (IgH) locus, this type of differential gene expression has been related to the absence of a transcriptional enhancer. To gain additional information on the role of the IgH enhancer, we examined expression driven by enhancers that were merely weakened, rather than fully deleted, using both mutations and insulators to impair enhancer activity. For this purpose we used a LoxP/Cre system to place a reporter gene at the same genomic site of a stable cell line. Whereas expression of the reporter gene was uniformly high in the presence of the normal, uninsulated enhancer and undetectable in its absence, weakened enhancers yielded variegated expression of the reporter gene; i.e., the average level of expression of the same gene differed in different clones, and expression varied significantly among cells within individual clones. These results indicate that the weakened enhancer allows the reporter gene to exist in at least two states. Subtle aspects of the variegation suggest that the IgH enhancer decreases the average duration (half-life) of the silent state. This analysis has also tested the conventional wisdom that enhancer activity is independent of distance and orientation. Thus, our analysis of mutant (truncated) forms of the IgH enhancer revealed that the 250 bp core enhancer was active in its normal position, ∼1.4 kb 3′ of the promoter, but inactive ∼6 kb 3′, indicating that the activity of the core enhancer was distance-dependent. A longer segment – the core enhancer plus ∼1 kb of 3′ flanking material, including the 3′ matrix attachment region – was active, and the activity of this longer segment was orientation-dependent. Our data suggest that this 3′ flank includes binding sites for at least two activators