bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategies for improving outcomes in venous leg ulcer care
Authors: Cowan Tracy
Published: July 2018

In May 2018, BSN Medical hosted a symposium, ‘The management of venous leg ulcers: the value of high-quality care’, at the European Wound Management Association (EWMA) conference in Poland. It focused on the impact of excessive exudate on venous leg ulcer outcomes, how to address it, and concluded with a stepwise strategy for improving the quality of care.
State-of-the-art diagnosis and surgical treatment of acute peri-prosthetic joint infection following primary total hip arthroplasty
Authors: Slullitel Pablo A. , Oñativia José I. , Buttaro Martin A. , Sánchez Marisa L. , Comba Fernando , Zanotti Gerardo , Piccaluga Francisco
Published: July 2018

Acute peri-prosthetic joint infection (PJI) following total hip arthroplasty (THA) is a potentially devastating and undesired complication, with a prevalence of 0.3% to 2.9%. Its suspicion begins with a meticulous physical examination and anamnesis. Diagnosis should be made on the basis of the Musculoskeletal Infection Society criteria. Serum and synovial biomarkers are very useful tools when major criteria are absent. Although sometimes not possible due to medical conditions, surgery is usually the first line of treatment. Although its outcome is highly correlated with the isolated microorganism, irrigation and debridement with implant retention (DAIR) is the gold standard for treatment. Ideally, the prior approach should be proximally and distally extended to augment the field of view and remove all of the prosthetic modular components, that is, femoral head and acetabular insert. Given DAIR’s unclear control of infection, with successful outcomes in the range of 30% to 95%, one- or two-stage revision protocols may play a role in certain cases of acute infections; nonetheless, further prospective, randomized studies are necessary to compare long-term outcomes between DAIR and revision surgeries. Following surgical treatment, length of antibiotherapy is in the range of six weeks to six months, without any difference in outcomes between short and long protocols. Treatment should be adjusted to the isolated bacteria and controlled further with post-operative serum biomarker levels.

Cite this article: EFORT Open Rev 2018;3:434-441. DOI: 10.1302/2058-5241.3.170032
Evaluation of Preanalytical Conditions and Implementation of Quality Control Steps for Reliable Gene Expression and DNA Methylation Analyses in Liquid Biopsies
Authors: Zavridou Martha , Mastoraki Sofia , Strati Areti , Tzanikou Eleni , Chimonidou Maria , Lianidou Evi
Published: July 2018

BACKGROUND

Liquid biopsy provides important information for the prognosis and treatment of cancer patients. In this study, we evaluated the effects of preanalytical conditions on gene expression and DNA methylation analyses in liquid biopsies.

METHODS

We tested the stability of circulating tumor cell (CTC) messenger RNA by spiking MCF-7 cells in healthy donor peripheral blood (PB) drawn into 6 collection-tube types with various storage conditions. CTCs were enriched based on epithelial cell adhesion molecule positivity, and RNA was isolated followed by cDNA synthesis. Gene expression was quantified using RT-quantitative PCR for CK19 and B2M. We evaluated the stability of DNA methylation in plasma under different storage conditions by spiking DNA isolated from MCF-7 cells in healthy donor plasma. Two commercially available sodium bisulfite (SB)-conversion kits were compared, in combination with whole genome amplification (WGA), to evaluate the stability of SB-converted DNA. SB-converted DNA samples were analyzed by real-time methylation-specific PCR (MSP) for ACTB, SOX17, and BRMS1. Quality control was assessed using Levey–Jennings graphs.

RESULTS

RNA-based analysis in CTCs is severely impeded by the preservatives used in many PB collection tubes (except for EDTA), as well as by time to analysis. Plasma and SB-converted DNA samples are stable and can be used safely for MSP when kept at −80 °C. Downstream WGA of SB-converted DNA compensated for the limited amount of available sample in liquid biopsies.

CONCLUSIONS

Standardization of preanalytical conditions and implementation of quality control steps is extremely important for reliable liquid biopsy analysis, and a prerequisite for routine applications in the clinic.
Seyfettin Erşahin, “İslam Tarihini Anlama Kılavuzu”
Authors: BİLGİN Muharrem Samet
Published: July 2018

Gelişen teknoloji, artan ve çeşitlenen basın yayın organları ve sosyal medyanın etkisiyle bilgiye ulaşmanın çok kolaylaştığı bir dönemi yaşıyoruz. İnsanlar ilgi duydukları, bilgi sahibi olmak istedikleri konularda yazılı, sesli, görsel pek çok malzemeyi kolaylıkla elde edebilmekteler. Bunlar sayesinde hem kafalarındaki sorulara cevap bulabilmekte hem de çevrelerindeki insanları aydınlatabilmekteler. Ancak böyle bir ortamda da farklı sorunlar ortaya çıkmaktadır. Bilgi kirliliği, metodoloji eksikliğinden kaynaklanan problemler, istenilen yönde algı yaratmak amacıyla bilginin kötüye kullanılması, elde edilen bilginin/haberin bağlamından koparılarak yorumlanması bu sorunlar arasında ilk akla gelenlerdir. Gerçi saydığımız son iki husus eskiden beri insanlar tarafından suiistimal edilmektedir. Fakat günümüzde iletişim araçlarının gelişmesi sayesinde kitlelere daha kolay hitap edildiğini düşünürsek bu oranın her zamankinden daha yüksek olduğu kanısına varabiliriz. İnsanların her zaman ilgisini çeken, gelişen ve değişen bu şartlar muvacehesinde de bilgi sahibi olmanın kolaylaştığı, üzerinde en çok konuşulan alanlar arasında din bilimleri ve tarihi sayabiliriz.
POLA RUANG DALAM LANSEKAP PEDESAAN: PENILAIAN PERUBAHAN GUNA LAHAN DAN TUTUPAN VEGETASI
Authors: Rudiarto Iwan , Handayani Wiwandari , Wijaya Holi Bina , Pangi Pangi
Published: July 2018

The existence of rural landscape is very significant in balancing the biohysical environment. The changing of landscape pattern in a rural area affects both the ecosystem and the habitat where eventually changes the human environment. Normaliazed Difference Vegetation Index/NDVI is one of the assessment that can be applied in determining the distribution of vegetation coverage. The analysis was carried out through the assessment of landsat satellite images in the year of 1990, 2010, and 2015 in three typical rural areas; coastal area, plain area, and mountain area. The result showed that coastal rural and plain rural area were the two areas that vegetation coverage significantly changed. This change is mostly found in the intermittent vegetation classification which identified as the agricultural and settlement area. While in the mountain area, the conversion was identified more on the agricultural area due to the expansion of agricultural activity to the higher area.
A necessary evil: the concept of ZULM in Arab political discourse and its historic roots
Authors: Bogomolov Alexander
Published: July 2018

A necessary evil: the concept of ZULM in Arab political discourse and its historic roots
Den første samnorskorganisasjonen 100 år – “Stlandsk reisning” blei stifta 1916
Authors: Jahr Ernst Håkon
Published: July 2018

Den første samnorskorganisasjonen 100 år – “Stlandsk reisning” blei stifta 1916
Postrzeganie i kategoryzacja barw (świat ludzi i zwierząt)
Authors: Narloch Andrzej
Published: July 2018

Postrzeganie i kategoryzacja barw (świat ludzi i zwierząt)
Bildungen mit -venlig im Dänischen und ihre polnischen Äquivalente
Authors: Szubert Andrzej
Published: July 2018

Bildungen mit -venlig im Dänischen und ihre polnischen Äquivalente
Wskaźnikowość twarzy ludzkiej: krótki przegląd problematyki
Authors: Puppel Joanna
Published: July 2018

Wskaźnikowość twarzy ludzkiej: krótki przegląd problematyki
A few aspects of well-known Athenian ISONOMIA in Ancient Greece and its opposition to the profession of a logographer
Authors: Tuszyńska Krystyna
Published: July 2018

A few aspects of well-known Athenian ISONOMIA in Ancient Greece and its opposition to the profession of a logographer
Estradiol Increases Glutamate and GABA Neurotransmission into GnRH Neurons via Retrograde NO-Signaling in Proestrous Mice during the Positive Estradiol Feedback Period
Authors: Farkas Imre , Bálint Flóra , Farkas Erzsébet , Vastagh Csaba , Fekete Csaba , Liposits Zsolt
Published: July 2018

Surge release of gonadotropin-releasing hormone (GnRH) is essential in the activation of pituitary gonadal unit at proestrus afternoon preceded by the rise of serum 17β-estradiol (E2) level during positive feedback period. Here, we describe a mechanism of positive estradiol feedback regulation acting directly on GnRH-green fluorescent protein (GFP) neurons of mice. Whole-cell clamp and loose patch recordings revealed that a high physiological dose of estradiol (200 pM), significantly increased firing rate at proestrus afternoon. The mPSC frequency at proestrus afternoon also increased, whereas it decreased at metestrus afternoon and had no effect at proestrus morning. Inhibition of the estrogen receptor β (ERβ), intracellular blockade of the Src kinase and phosphatidylinositol 3 kinase (PI3K) and scavenge of nitric oxide (NO) inside GnRH neurons prevented the facilitatory estradiol effect indicating involvement of the ERβ/Src/PI3K/Akt/nNOS pathway in this fast, direct stimulatory effect. Immunohistochemistry localized soluble guanylate cyclase, the main NO receptor, in both glutamatergic and GABAergic terminals innervating GnRH neurons. Accordingly, estradiol facilitated neurotransmissions to GnRH neurons via both GABAA-R and glutamate/AMPA/kainate-R. These results indicate that estradiol acts directly on GnRH neurons via the ERβ/Akt/nNOS pathway at proestrus afternoon generating NO that retrogradely accelerates GABA and glutamate release from the presynaptic terminals contacting GnRH neurons. The newly explored mechanism might contribute to the regulation of the GnRH surge, a fundamental prerequisite of the ovulation.
Functional Connectivity of Chronic Cocaine Use Reveals Progressive Neuroadaptations in Neocortical, Striatal, and Limbic Networks
Authors: Orsini Caitlin A. , Colon-Perez Luis M. , Heshmati Sara C. , Setlow Barry , Febo Marcelo
Published: July 2018

Brain imaging studies indicate that chronic cocaine users display altered functional connectivity between prefrontal cortical, thalamic, striatal, and limbic regions; however, the use of cross-sectional designs in these studies precludes measuring baseline brain activity prior to cocaine use. Animal studies can circumvent this limitation by comparing functional connectivity between baseline and various time points after chronic cocaine use. In the present study, adult male Long–Evans rats were trained to self-administer cocaine intravenously for 6 h sessions daily over 14 consecutive days. Two additional groups serving as controls underwent sucrose self-administration or exposure to the test chambers alone. Functional magnetic resonance imaging was conducted before self-administration and after 1 and 14 d of abstinence (1d and 14d Abs). After 1d Abs from cocaine, there were increased clustering coefficients in brain areas involved in reward seeking, learning, memory, and autonomic and affective processing, including amygdala, hypothalamus, striatum, hippocampus, and thalamus. Similar changes in clustering coefficient after 1d Abs from sucrose were evident in predominantly thalamic brain regions. Notably, there were no changes in strength of functional connectivity at 1 or 14 d after either cocaine or sucrose self-administration. The results suggest that cocaine and sucrose can change the arrangement of functional connectivity of brain regions involved in cognition and emotion, but that these changes dissipate across the early stages of abstinence. The study also emphasizes the importance of including baseline measures in longitudinal functional neuroimaging designs seeking to assess functional connectivity in the context of substance use.
Diálogos em roda: contribuições para a formação de educadores e educandos na educação formal e não formal
Authors: Machado Maria Elisabete , Freitas Ana Lúcia Souza de
Published: July 2018

Este artigo resulta de uma dissertação e tem como objetivo compartilhar a metodologia utilizada, considerando suas contribuições para o campo da formação de educadores. A metodologia qualitativa, de natureza participativa, foi aplicada por meio dos diálogos em roda, realizados com o apoio de diários elaborados por todos os participantes da pesquisa: os educandos de uma turma do ensino fundamental e os educadores e educadoras de uma instituição de educação não formal. Essa proposição tem origem na experiência da pesquisadora como integrante da Roda Cultural de Leituras Freireanas, promovida por um grupo de pesquisa na universidade. Desta trilogia de rodas – na universidade, na escola e no espaço de educação não formal – resulta a compreensão acerca do potencial formativo do pensamento freireano para orientar a reflexão sobre a prática nos diálogos em roda, tendo em vista constituir processos educativos emancipatórios, tanto para os educandos quanto para os educadores e educadoras.
Problematizando discursos educacionais críticos em Meu professor é o cara
Authors: Peil Ana Paula Quevedo , Bicca Angela Dillmann Nunes
Published: July 2018

A mídia educativa vem acionando discursos educacionais que têm colaborado para a produção de docentes de determinados tipos. Atentando para tal atuação, inseridas nos estudos culturais de inspiração pós-estruturalista, objetivou-se problematizar alguns elementos desses discursos educacionais acionados de forma recorrente no quadro Meu professor é o cara, integrante do programa de televisão Como será? da Rede Globo de Televisão. Os episódios analisados indicam que os/as professores/as destacados/as procuraram afastar-se ao máximo do qualificado como ensino tradicional, valorizando aspectos dos discursos educacionais críticos e enfatizando que a aprendizagem se efetiva a partir da reconfiguração do espaço de sala de aula e de investimentos na afetividade. O que proporciona uma prática considerada diferenciada.
De ciudadanos a nación, la historia invertida. Cuba: diferencias y afinidades con las formaciones nacionales latinoamericanas en el siglo XIX.
Authors: Alvarez Pitaluga Antonio Nestor
Published: July 2018

El artículo pretende explicar cómo y porqué la formación de la nacionalidad y la nación en la mayor isla del Caribe ocurrió de manera contrapuesta a la mayoría de los países de América Latina. La etapa escogida va desde el surgimiento de la plantación esclavita en Cuba, pasando por las independencias latinoamericanas, hasta el final de la formación de los estados nacionales en el continente y final del siglo XIX, es decir, de 1790-1898. A través de los principales acontecimientos y hechos que explican el fenómeno mencionado, se ofrecen algunas claves interpretativas para conocer no solo las diferencias, sino también las afinidades entre el proceso cubano y el latinoamericano. Por último, se concluye que la formación histórica cubana transcurrió de manera paralela a sus homólogas latinoamericanas generando algunas particularidades históricas que sirve para comprender determinados aspectos de su presente nacional.
La dictadura argentina frente al estallido de la guerra civil salvadoreña (1977-1982): proyección continental y “experiencias compartidas”
Authors: Molinari Lucrecia
Published: July 2018

El presente texto tiene como objetivo describir las relaciones diplomáticas entre el gobierno argentino y el salvadoreño, entre los años 1977 y 1982, en base a las comunicaciones que la Embajada Argentina en El Salvador enviaba a la cancillería argentina.Por el tipo de documentos utilizados –cables oficiales, secretos y públicos- el eje estará puesto en aquella actuación oficial del gobierno dictatorial argentino, sin avanzar en las actividades extraterritoriales y clandestinas que también se llevaron adelante en el período, y que son un muy recientemente abordado objeto de estudio.Este trabajo permitirá complementar los mencionados estudios sobre el aparato clandestino lo que posibilitará plantear posibles conexiones entre la faz clandestina y la faz diplomática o legal.Finalmente, el presente artículo buscó –en tanto primer análisis de la documentación a la que se accedió- proponer una periodización desde una mirada a mediano plazo. Dividida en siete etapas de diversa duración, dicha periodización está marcada por sucesos o hitos de importancia en la relación entre ambos gobiernos. Dicha importancia radica en la forma en que estos impactan en la proyección continental de la dictadura argentina o en la manera en que cambian el escenario donde dichas relaciones se desarrollan.
Determinación de las propiedades mecánicas del cuero fino de vaca sometido a condiciones variadas de temperatura y humedad
Authors: Briguido Jose Miguel , Calderón Julieta Fabiana , Recchioni Liliana Laura , Diaz Adriana Cecilia
Published: July 2018

Este proyecto consiste en someter distintas probetas de cuero tipo (SOFT) de mayor calidad y costo, a tres tipos de ensayos mecánicos: determinación de la resistencia a la tracción y del alargamiento porcentual, determinación de la resistencia al desgarramiento mediante el método de los 2 bordes y  ensayo de desgarramiento en un punto de costura por el método de los dos orificios.El objetivo es observar si la resistencia del cuero a determinadas condiciones de temperatura y humedad sufre alguna modificación significativa. Se utilizó un modelo completamente aleatorizado y un modelo estadístico de covariable y pruebas a posteriori se realizaron pruebas de acuerdo A Fisher.La estimación de parámetros se realizó de acuerdo con el método REML (Restricted Maximum Likelihood) utilizando el software InfoStat. Después de probar la igualdad de efectos del tratamiento, se prueba normalidad con Shapiro Wilks a un nivel de significación del 1%.Se concluye que existe gran heterogeneidad en las mediciones en todas las variables bajo diferentes tratamientos de humedad y temperatura, dados los altos valores de coeficientes de variación y que las  propiedades mecánicas del tipo de cuero soft, no tienen variación significativa cuando se somete a condiciones diferentes de lo normal.
Efecto de sales de boro en la densidad y en el módulo de elasticidad de tres maderas mexicanas
Authors: Sotomayor-Castellanos Javier-Ramón
Published: July 2018

Las especies Guazuma ulmifolia, Spathodea campanulata y Abies religiosa tienen potencial para la fabricación de productos de madera con valor agregado. Sin embargo, no existe información sobre sus propiedades de retención de substancias protectoras, ni de su posible efecto sobre la densidad y el módulo de elasticidad. El objetivo de la investigación fue analizar el efecto del tratamiento con baño caliente-frío de sales de boro sobre la densidad y el módulo de elasticidad en muestras de madera de G. ulmifolia, S. campanulata y A. religiosa. Antes y después del tratamiento se determinaron la densidad de la madera, el módulo de elasticidad en flexión estática y la retención de sales de boro. Se realizaron pruebas de diferencias de medias y después del tratamiento se efectuó entre las tres especies un análisis de varianza de la variable retención. En las muestras de madera de G. ulmifolia, S. campanulata y A. religiosa la retención de sales de boro fue diferente para cada una de ellas. La densidad después de aplicar las sales aumentó en G. ulmifolia y A. religiosa y disminuyó en S. campanulata. Las sales de boro no modificaron el módulo de elasticidad de la madera de las tres especies.
Clasificación de las rutas de la red de transporte público modalidad autobús de Costa Rica
Authors: Quiros-Calderon Cristhian Santiago , Aguero-Valverde Jonathan
Published: July 2018

Este artículo presenta una metodología utilizada para la clasificación de las distintas rutas que componen la totalidad de la red de transporte público modalidad autobús de Costa Rica. El procedimiento se realiza a partir de la necesidad de identificar rutas con problemas tarifarios que terminan por trasladar los costos de operación a los usuarios, para lo cual la desagregación en subgrupos a partir de características comunes facilita la tarea.   Debido a la carencia de información relacionada con las características de operación de la red nacional de transporte público, la categorización se realiza aprovechando las variables con la mayor cantidad de información disponible, en este caso: ubicación, estructura, extensión y pendiente. El proceso consiste en la combinación de los subgrupos de las variables seleccionadas, en un orden de jerarquía, con el objetivo de llevar a cabo la agrupación de ramales que presenten comportamientos homogéneos, que faciliten la identificación de rutas con comportamientos atípicos respecto a la tarifa cobrada. Como resultado se obtienen grupos más homogéneos, reflejado en la reducción de la dispersión de las distintas variables analizadas.
Comportamiento a flexión de losas de puentes de concreto, reforzadas externamente con CFRP
Authors: Navas Carro Alejandro , Fonseca Mojica Carolina
Published: July 2018

Se evaluó el comportamiento a flexión de secciones de losas de puentes de concreto que fueron sometidas a un estado de agrietamiento y posteriormente reparadas con polímeros reforzados con fibras de carbono (CFRP).Se construyeron tres losas de concreto: un espécimen de tipo control (sin refuerzo con CFRP) y dos especímenes para evaluar el refuerzo con CFRP. El esquema de carga consistió en colocar las losas sobre tres apoyos simples y aplicar dos cargas puntuales que generasen momento positivo y negativo. Se sometieron las losas por reforzar a un 80% de su carga última para generar agrietamiento que requiriese reparación. Se repararon las grietas cuyos anchos de grieta superaron los 0.3 mm mediante inyección de epóxico y se reforzaron los dos especímenes con CFRP en las zonas de momento positivo y negativo. Finalmente se cargaron los tres especímenes hasta la falla.Se obtuvo que las losas reforzadas con CFRP fueron 36% más resistentes que la losa control. Además se compararon los resultados experimentales de este proyecto con los resultados de la investigación de Carranza (2017). Se concluyó que ambas investigaciones dieron resultados similares, con porcentajes de diferencia entre un 10% y 14%.
Desempeño mecánico de montajes de líneas de distribución de energía eléctrica
Authors: Fernández Vásquez Raúl
Published: July 2018

Inicialmente, mediante la revisión de normativa de otros países sobre los factores de seguridad para el diseño mecánico de líneas de distribución se concluye que lo más conveniente para las condiciones de la Compañía Nacional de Fuerza y Luz (CNFL) es la aplicación de los valores establecidos en el código de seguridad nacional de Estados Unidos de Norteamérica NESC. Seguidamente se realiza un análisis de esfuerzos en los montajes que se utilizan actualmente mediante modelado por elementos finitos obteniendo que para todos los casos, los montajes están subutilizados. También se realiza un análisis mediante equilibrio estático en los pernos que sujetan los montajes concluyendo que también son subutilizados.
Empleo del método espectroscópico UV-Visible para la determinación de asfaltenos en crudos extrapesados
Authors: Bernal Samaniego Cesar Augusto
Published: July 2018

En este estudio se determinó la cantidad de asfáltenos obtenidos en crudo extrapesados resultantes de la aplicación del proceso de desasfaltación por el método espectroscópico UV-visible, con la finalidad de determinar si el método anteriormente estandarizado para crudos pesados podía emplearse en crudos extrapesados y obtener buenas correlaciones a la hora de la determinación.  Se demuestra que efectivamente se puede emplear este método tanto para crudos pesados como extra pesados, como una alternativa para determinar contenido de asfaltenos; disminuyendo el tiempo de análisis y contenido de disolvente empleados en los métodos tradicionales ASTM.
GENE DIVERSITY IN GREVILLEA POPULATIONS INTRODUCED IN BRAZIL AND ITS IMPLICATION ON MANAGEMENT OF GENETIC RESOURCES
Authors: Sousa Valderês Aparecida de , Kalil Filho Antonio Nascim , Martins Emerson Gonçalves , Shimizu Jarbas Yukio , Albertin Fernando
Published: July 2018

ABSTRACT We describe isoenzymes variability in six populations of Grevillea robusta from a provenances and progenies test established in a randomized block design with five plants per replication in Southern Brazil. The population genetic structure was examined by using biochemical markers in 5-year old trees, specifically at MDH-3, PGM-2, DIA-2, PO-1, PO-2, SOD-1, and SKDH-1 loci. The northern provenances (Rathdowney and Woodenbong) showed a strong divergence in relation to the average of provenances when alleles per locus (Ap), allele richness (Rs), Nei's gene diversity (H), and inbreeding coefficient (f) were considered. Inbreeding in varying degrees was detected. The commercial control showed the highest inbreeding coefficient, (f = 0.4448), whereas the provenance average was f = 0.2306, possibly due to insufficient sampling of populations in their origin (Australia). Despite its restricted natural range, a positive correlation between genetic divergence and geographic distance among original populations was detected. Genetic distance and cluster analyses based on the Bayesian model revealed three distinct provenance groups: 1) Rathdowney-QLD and Woodenbong-QLD; 2) Paddy's Flat-NSW; and 3) Mann River-NSW, Boyd River-NSW and the commercial control (material used in Brazil). The grouping of the control to both Mann River-NSW and Boyd River-NSW provenances suggests that the northern provenances have the highest potential for genetic improvement of wood productivity in Brazil, due to their high genetic diversity and low inbreeding coefficient.
Enhancing QA Systems with Complex Temporal Question Processing Capabilities
Authors: Saquete E. , Vicedo J. Luis , Martínez-Barco P. , Muñoz R. , Llorens H.
Published: July 2018

This paper presents a multilayered architecture that enhances the capabilities of current QA systems and allows different types of complex questions or queries to be processed. The answers to these questions need to be gathered from factual information scattered throughout different documents. Specifically, we designed a specialized layer to process the different types of temporal questions. Complex temporal questions are first decomposed into simple questions, according to the temporal relations expressed in the original question. In the same way, the answers to the resulting simple questions are recomposed, fulfilling the temporal restrictions of the original complex question. A novel aspect of this approach resides in the decomposition which uses a minimal quantity of resources, with the final aim of obtaining a portable platform that is easily extensible to other languages. In this paper we also present a methodology for evaluation of the decomposition of the questions as well as the ability of the implemented temporal layer to perform at a multilingual level. The temporal layer was first performed for English, then evaluated and compared with: a) a general purpose QA system (F-measure 65.47% for QA plus English temporal layer vs. 38.01% for the general QA system), and b) a well-known QA system. Much better results were obtained for temporal questions with the multilayered system. This system was therefore extended to Spanish and very good results were again obtained in the evaluation (F-measure 40.36% for QA plus Spanish temporal layer vs. 22.94% for the general QA system).
Friends or Foes? On Planning as Satisfiability and Abstract CNF Encodings
Authors: Domshlak C. , Hoffmann J. , Sabharwal A.
Published: July 2018

Planning as satisfiability, as implemented in, for instance, the SATPLAN tool, is a highly competitive method for finding parallel step-optimal plans. A bottleneck in this approach is to *prove the absence* of plans of a certain length. Specifically, if the optimal plan has N steps, then it is typically very costly to prove that there is no plan of length N-1. We pursue the idea of leading this proof within solution length preserving abstractions (over-approximations) of the original planning task. This is promising because the abstraction may have a much smaller state space; related methods are highly successful in model checking. In particular, we design a novel abstraction technique based on which one can, in several widely used planning benchmarks, construct abstractions that have exponentially smaller state spaces while preserving the length of an optimal plan.

Surprisingly, the idea turns out to appear quite hopeless in the context of planning as satisfiability. Evaluating our idea empirically, we run experiments on almost all benchmarks of the international planning competitions up to IPC 2004, and find that even hand-made abstractions do not tend to improve the performance of SATPLAN. Exploring these findings from a theoretical point of view, we identify an interesting phenomenon that may cause this behavior. We compare various planning-graph based CNF encodings F of the original planning task with the CNF encodings F_abs of the abstracted planning task. We prove that, in many cases, the shortest resolution refutation for F_abs can never be shorter than that for F. This suggests a fundamental weakness of the approach, and motivates further investigation of the interplay between declarative transition-systems, over-approximating abstractions, and SAT encodings.
Join-Graph Propagation Algorithms
Authors: Mateescu R. , Kask K. , Gogate V. , Dechter R.
Published: July 2018

The paper investigates parameterized approximate message-passing schemes that are based on bounded inference and are inspired by Pearls belief propagation algorithm (BP). We start with the bounded inference mini-clustering algorithm and then move to the iterative scheme called Iterative Join-Graph Propagation (IJGP), that combines both iteration and bounded inference. Algorithm IJGP belongs to the class of Generalized Belief Propagation algorithms, a framework that allowed connections with approximate algorithms from statistical physics and is shown empirically to surpass the performance of mini-clustering and belief propagation, as well as a number of other state-of-the-art algorithms on several classes of networks. We also provide insight into the accuracy of iterative BP and IJGP by relating these algorithms to well known classes of constraint propagation schemes.
Predicting the Performance of IDA* using Conditional Distributions
Authors: Zahavi U. , Felner A. , Burch N. , Holte R. C.
Published: July 2018

Korf, Reid, and Edelkamp introduced a formula to predict the number of nodes IDA* will expand on a single iteration for a given consistent heuristic, and experimentally demonstrated that it could make very accurate predictions. In this paper we show that, in addition to requiring the heuristic to be consistent, their formula's predictions are accurate only at levels of the brute-force search tree where the heuristic values obey the unconditional distribution that they defined and then used in their formula. We then propose a new formula that works well without these requirements, i.e., it can make accurate predictions of IDA*'s performance for inconsistent heuristics and if the heuristic values in any
level do not obey the unconditional distribution. In order to achieve this we introduce the conditional distribution of heuristic values which is a generalization of their unconditional heuristic distribution. We also provide extensions of our formula that handle individual start states and the augmentation of IDA* with bidirectional pathmax (BPMX), a technique for propagating heuristic values when inconsistent heuristics are used. Experimental results demonstrate the accuracy of our new method and all its variations.
The Role of Macros in Tractable Planning
Authors: Jonsson A.
Published: July 2018

This paper presents several new tractability results for planning based on macros. We describe an algorithm that optimally solves planning problems in a class that we call inverted tree reducible, and is provably tractable for several subclasses of this class. By using macros to store partial plans that recur frequently in the solution, the algorithm is polynomial in time and space even for exponentially long plans. We generalize the inverted tree reducible class in several ways and describe modifications of the algorithm to deal with these new classes. Theoretical results are validated in experiments.
Reasoning About the Transfer of Control
Authors: Van der Hoek W. , Walther D. , Wooldridge M.
Published: July 2018

We present DCL-PC: a logic for reasoning about how the abilities of agents and coalitions of agents are altered by transferring control from one agent to another. The logical foundation of DCL-PC is CL-PC, a logic for reasoning about cooperation in which the abilities of agents and coalitions of agents stem from a distribution of atomic Boolean variables to individual agents -- the choices available to a coalition correspond to assignments to the variables the coalition controls. The basic modal constructs of DCL-PC are of the form `coalition C can cooperate to bring about phi'. DCL-PC extends CL-PC with dynamic logic modalities in which atomic programs are of the form `agent i gives control of variable p to agent j'; as usual in dynamic logic, these atomic programs may be combined using sequence, iteration, choice, and test operators to form complex programs. By combining such dynamic transfer programs with cooperation modalities, it becomes possible to reason about how the power of agents and coalitions is affected by the transfer of control. We give two alternative semantics for the logic: a `direct' semantics, in which we capture the distributions of Boolean variables to agents; and a more conventional Kripke semantics. We prove that these semantics are equivalent, and then present an axiomatization for the logic. We investigate the computational complexity of model checking and satisfiability for DCL-PC, and show that both problems are PSPACE-complete (and hence no worse than the underlying logic CL-PC). Finally, we investigate the characterisation of control in DCL-PC. We distinguish between first-order control -- the ability of an agent or coalition to control some state of affairs through the assignment of values to the variables under the control of the agent or coalition -- and second-order control -- the ability of an agent to exert control over the control that other agents have by transferring variables to other agents. We give a logical characterisation of second-order control.
RoxyBot-06: Stochastic Prediction and Optimization in TAC Travel
Authors: Greenwald A. , Lee S. , Naroditskiy V.
Published: July 2018

In this paper, we describe our autonomous bidding agent, RoxyBot, who emerged victorious in the travel division of the 2006 Trading Agent Competition in a photo finish. At a high level, the design of many successful trading agents can be summarized as follows: (i) price prediction: build a model of market prices; and (ii) optimization: solve for an approximately optimal set of bids, given this model. To predict, RoxyBot builds a stochastic model of market prices by simulating simultaneous ascending auctions. To optimize, RoxyBot relies on the sample average approximation method, a stochastic optimization technique.
Context-based Word Acquisition for Situated Dialogue in a Virtual World
Authors: Qu S. , Chai J. Y.
Published: July 2018

To tackle the vocabulary problem in conversational systems, previous work has applied unsupervised learning approaches on co-occurring speech and eye gaze during interaction to automatically acquire new words. Although these approaches have shown promise, several issues related to human language behavior and human-machine conversation have not been addressed. First, psycholinguistic studies have shown certain temporal regularities between human eye movement and language production. While these regularities can potentially guide the acquisition process, they have not been incorporated in the previous unsupervised approaches. Second, conversational systems generally have an existing knowledge base about the domain and vocabulary. While the existing knowledge can potentially help bootstrap and constrain the acquired new words, it has not been incorporated in the previous models. Third, eye gaze could serve different functions in human-machine conversation. Some gaze streams may not be closely coupled with speech stream, and thus are potentially detrimental to word acquisition. Automated recognition of closely-coupled speech-gaze streams based on conversation context is important. To address these issues, we developed new approaches that incorporate user language behavior, domain knowledge, and conversation context in word acquisition. We evaluated these approaches in the context of situated dialogue in a virtual world. Our experimental results have shown that incorporating the above three types of contextual information significantly improves word acquisition performance.
On Action Theory Change
Authors: Varzinczak I. J.
Published: July 2018

As historically acknowledged in the Reasoning about Actions and Change community, intuitiveness of a logical domain description cannot be fully automated. Moreover, like any other logical theory, action theories may also evolve, and thus knowledge engineers need revision methods to help in accommodating new incoming information about the behavior of actions in an adequate manner. The present work is about changing action domain descriptions in multimodal logic. Its contribution is threefold: first we revisit the semantics of action theory contraction proposed in previous work, giving more robust operators that express minimal change based on a notion of distance between Kripke-models. Second we give algorithms for syntactical action theory contraction and establish their correctness with respect to our semantics for those action theories that satisfy a principle of modularity investigated in previous work. Since modularity can be ensured for every action theory and, as we show here, needs to be computed at most once during the evolution of a domain description, it does not represent a limitation at all to the method here studied. Finally we state AGM-like postulates for action theory contraction and assess the behavior of our operators with respect to them. Moreover, we also address the revision counterpart of action theory change, showing that it benefits from our semantics for contraction.
Developing Approaches for Solving a Telecommunications Feature Subscription Problem
Authors: Lesaint D. , Mehta D. , O'Sullivan B. , Quesada L. , Wilson N.
Published: July 2018

Call control features (e.g., call-divert, voice-mail) are primitive options to which users can subscribe off-line to personalise their service. The configuration of a feature subscription involves choosing and sequencing features from a catalogue and is subject to constraints that prevent undesirable feature interactions at run-time. When the subscription requested by a user is inconsistent, one problem is to find an optimal relaxation, which is a generalisation of the feedback vertex set problem on directed graphs, and thus it is an NP-hard task. We present several constraint programming formulations of the problem. We also present formulations using partial weighted maximum Boolean satisfiability and mixed integer linear programming. We study all these formulations by experimentally comparing them on a variety of randomly generated instances of the feature subscription problem.
Automatic Induction of Bellman-Error Features for Probabilistic Planning
Authors: Wu J. , Givan R.
Published: July 2018

Domain-specific features are important in representing problem structure throughout machine learning and decision-theoretic planning. In planning, once state features are provided, domain-independent algorithms such as approximate value iteration can learn weighted combinations of those features that often perform well as heuristic estimates of state value (e.g., distance to the goal). Successful applications in real-world domains often require features crafted by human experts. Here, we propose automatic processes for learning useful domain-specific feature sets with little or no human intervention. Our methods select and add features that describe state-space regions of high inconsistency in the Bellman equation (statewise Bellman error) during approximate value iteration. Our method can be applied using any real-valued-feature hypothesis space and corresponding learning method for selecting features from training sets of state-value pairs. We evaluate the method with hypothesis spaces defined by both relational and propositional feature languages, using nine probabilistic planning domains. We show that approximate value iteration using a relational feature space performs at the state-of-the-art in domain-independent stochastic relational planning. Our method provides the first domain-independent approach that plays Tetris successfully (without human-engineered features).
Algorithms for Closed Under Rational Behavior (CURB) Sets
Authors: Benisch M. , Davis G. B. , Sandholm T.
Published: July 2018

We provide a series of algorithms demonstrating that solutions according to the fundamental game-theoretic solution concept of closed under rational behavior (CURB) sets in two-player, normal-form games can be computed in polynomial time (we also discuss extensions to n-player games). First, we describe an algorithm that identifies all of a players best responses conditioned on the belief that the other player will play from within a given subset of its strategy space. This algorithm serves as a subroutine in a series of polynomial-time algorithms for finding all minimal CURB sets, one minimal CURB set, and the smallest minimal CURB set in a game. We then show that the complexity of finding a Nash equilibrium can be exponential only in the size of a games smallest CURB set. Related to this, we show that the smallest CURB set can be an arbitrarily small portion of the game, but it can also be arbitrarily larger than the supports of its only enclosed Nash equilibrium. We test our algorithms empirically and find that most commonly studied academic games tend to have either very large or very small minimal CURB sets.
Cooperative Games with Overlapping Coalitions
Authors: Chalkiadakis G. , Elkind E. , Markakis E. , Polukarov M. , Jennings N. R.
Published: July 2018

In the usual models of cooperative game theory, the outcome of a coalition formation process is either the grand coalition or a coalition structure that consists of disjoint coalitions. However, in many domains where coalitions are associated with tasks, an agent may be involved in executing more than one task, and thus may distribute his resources among several coalitions. To tackle such scenarios, we introduce a model for cooperative games with overlapping coalitionsor overlapping coalition formation (OCF) games. We then explore the issue of stability in this setting. In particular, we introduce a notion of the core, which generalizes the corresponding notion in the traditional (non-overlapping) scenario. Then, under some quite general conditions, we characterize the elements of the core, and show that any element of the core maximizes the social welfare. We also introduce a concept of balancedness for overlapping coalitional games, and use it to characterize coalition structures that can be extended to elements of the core. Finally, we generalize the notion of convexity to our setting, and show that under some natural assumptions convex games have a non-empty core. Moreover, we introduce two alternative notions of stability in OCF that allow a wider range of deviations, and explore the relationships among the corresponding definitions of the core, as well as the classic (non-overlapping) core and the Aubin core. We illustrate the general properties of the three cores, and also study them from a computational perspective, thus obtaining additional insights into their fundamental structure.
Efficient Planning under Uncertainty with Macro-actions
Authors: He R. , Brunskill E. , Roy N.
Published: July 2018

Deciding how to act in partially observable environments remains an active area of research. Identifying good sequences of decisions is particularly challenging when good control performance requires planning multiple steps into the future in domains with many states. Towards addressing this challenge, we present an online, forward-search algorithm called the Posterior Belief Distribution (PBD). PBD leverages a novel method for calculating the posterior distribution over beliefs that result after a sequence of actions is taken, given the set of observation sequences that could be received during this process. This method allows us to efficiently evaluate the expected reward of a sequence of primitive actions, which we refer to as macro-actions. We present a formal analysis of our approach, and examine its performance on two very large simulation experiments: scientific exploration and a target monitoring domain. We also demonstrate our algorithm being used to control a real robotic helicopter in a target monitoring experiment, which suggests that our approach has practical potential for planning in real-world, large partially observable domains where a multi-step lookahead is required to achieve good performance.
Exploiting Structure in Weighted Model Counting Approaches to Probabilistic Inference
Authors: Li W. , Poupart P. , Van Beek P.
Published: July 2018

Previous studies have demonstrated that encoding a Bayesian network into a SAT formula and then performing weighted model counting using a backtracking search algorithm can be an effective method for exact inference. In this paper, we present techniques for improving this approach for Bayesian networks with noisy-OR and noisy-MAX relations---two relations that are widely used in practice as they can dramatically reduce the number of probabilities one needs to specify. In particular, we present two SAT encodings for noisy-OR and two encodings for noisy-MAX that exploit the structure or semantics of the relations to improve both time and space efficiency, and we prove the correctness of the encodings. We experimentally evaluated our techniques on large-scale real and randomly generated Bayesian networks. On these benchmarks, our techniques gave speedups of up to two orders of magnitude over the best previous approaches for networks with noisy-OR/MAX relations and scaled up to larger networks. As well, our techniques extend the weighted model counting approach for exact inference to networks that were previously intractable for the approach.
The Complexity of Integer Bound Propagation
Authors: Bordeaux L. , Katsirelos G. , Narodytska N. , Vardi M. Y.
Published: July 2018

Bound propagation is an important Artificial Intelligence technique used in Constraint Programming tools to deal with numerical constraints. It is typically embedded within a search procedure (branch and prune) and used at every node of the search tree to narrow down the search space, so it is critical that it be fast. The procedure invokes constraint propagators until a common fixpoint is reached, but the known algorithms for this have a pseudo-polynomial worst-case time complexity: they are fast indeed when the variables have a small numerical range, but they have the well-known problem of being prohibitively slow when these ranges are large. An important question is therefore whether strongly-polynomial algorithms exist that compute the common bound consistent fixpoint of a set of constraints. This paper answers this question. In particular we show that this fixpoint computation is in fact NP-complete, even when restricted to binary linear constraints.