Analysis of Dyscalculia Evidences through Artificial Intelligence Systems

Dyscalculia is usually perceived of as a specific learning difficulty for mathematics or, more appropriately, arithmetic. Because definitions and diagnoses of dyscalculia are in their infancy and sometimes are contradictory. However, mathematical learning difficulties are certainly not in their infancy and are very prevalent and often devastating in their impact. Co-occurrence of learning disorders appears to be the rule rather than the exception. Co-occurrence is generally assumed to be a consequence of risk factors that are shared between disorders, for example, working memory. However, it should not be assumed that all dyslexics have problems with mathematics, although the percentage may be very high, or that all dyscalculics have problems with reading and writing. Because mathematics is very developmental, any insecurity or uncertainty in early topics will impact on later topics, hence to need to take intervention back to basics. However, it may be worked out in order to decrease its degree of severity. For example, disMAT, an app developed for android may help children to apply mathematical concepts, without much effort, that is turning in itself, a promising tool to dyscalculia treatment. Thus, this work will focus on the development of a Decision Support System to estimate children evidences of dyscalculia, based on data obtained on-the-fly with disMAT. The computational framework is built on top of a Logic Programming approach to Knowledge Representation and Reasoning, grounded on a Case-based approach to computing, that allows for the handling of incomplete, unknown, or even self-contradictory information.

Modificazioni del segnale EEG in un compito di memoria visiva con distrattori visivi ‘deboli’ e ‘forti’

La valutazione del segnale elettroencefalografico acquisito durante compiti di Working Memory è utile per indagare regioni e meccanismi cerebrali alla base della capacità di immagazzinare le informazioni provenienti dall’ambiente rilevanti per il task da svolgere e di inibire stimoli irrilevanti/distraenti. In questo lavoro di Tesi è stato condotto uno studio su 13 volontari che hanno svolto un compito di memoria di lavoro visiva, consistente di prove ripetute (trial) ognuna composta di diverse fasi: Encoding (memorizzazione del memory set), Retention (mantenimento in memoria) in cui si mostra un distrattore, che può essere weak (poco interferente) o strong (maggiormente interferente). Ciascun trial termina con la comparsa della Probe, a cui il soggetto deve rispondere indicando se apparteneva o meno al memory set. Durante il task è stato acquisito il segnale EEG da 64 elettrodi, ed analizzato per indagare i potenziali evocati (ERPs) e la sincronizzazione/desincronizzazione in banda alpha (8-12 Hz) e theta (4-8 Hz) correlata agli stimoli visivi; è stata svolta anche un’analisi preliminare ricostruendo l’attività delle sorgenti corticali dal segnale EEG. Dalle analisi emerge che gli ERPs sono visibili principalmente nelle fasi di Encoding e Distractor, e nelle regioni fronto-centrali e parieto-occipitali, e che nella fase di Distractor sono maggiori per distrattore weak rispetto a strong. Si conferma la natura inibitoria del ritmo alpha e il ruolo del ritmo theta nei processi cognitivi; infatti la potenza in banda alpha aumenta nella fase pre-distrattore (sia weak che strong) e la potenza in banda theta è sostenuta durante l’intero task. Non si osservano differenze in banda alpha e theta tra i due distrattori nella fase pre-distrattore, mentre si osserva una modulazione durante la presentazione del distrattore.

Effetto di distrattori acustici rispetto a distrattori visivi in un compito di memoria visiva: analisi del segnale EEG

Studi recenti hanno evidenziato cambiamenti nei ritmi alpha (8-12 Hz) e theta (4-8 Hz) in vari processi modulatori top-down e di controllo cognitivo come la memoria di lavoro (WM, working memory) e la soppressione di distrattori. I compiti di WM richiedono attenzione interna sostenuta per dare priorità alle informazioni rilevanti a discapito di quelle interferenti che distraggono dall’obiettivo. I meccanismi di attenzione in tali compiti sono associati ad aumento di potenza alpha, che riflette la funzione inibitoria di tale ritmo, in regioni che elaborano informazioni distraenti, e ad aumento di potenza theta, soprattutto in regioni frontali, che riflette funzioni di controllo cognitivo per raggiungere l’obiettivo pur in presenza di interferenze. Questo lavoro è volto ad indagare gli effetti di distrattori acustici rispetto a distrattori visivi in un compito di visual WM. A tale scopo sono stati acquisiti ed elaborati i segnali EEG di 12 soggetti volontari mentre eseguivano un compito di visual WM, in cui la fase di retention (mantenimento in memoria delle informazioni codificate) veniva interrotta con la presentazione di distrattori di due modalità sensoriali differenti (visiva e acustica), per valutare le variazioni dell’attività cerebrale in termini di ritmi alpha e theta e le regioni coinvolte. Si è osservato un aumento maggiore di potenza alpha (principalmente posteriore) in presenza del distrattore acustico rispetto al visivo sia nella fase pre-distrattore che nella fase distrattore, statisticamente significativo nella fase distrattore. Si è osservato un aumento maggiore di potenza theta (principalmente frontale) in presenza del distrattore acustico rispetto al visivo in tutte le fasi del task, statisticamente significativo nella fase iniziale di retention e nella fase del distrattore. I risultati potrebbero indicare una maggiore necessità di controllo cognitivo e di protezione da stimoli interferenti in caso di distrattore acustico rispetto al visivo.

Concentration, Working Speed and Memory: Cognitive Problems in Young Childhood Cancer Survivors and Their Siblings.

BACKGROUND Cognitive problems can have a negative effect on a person's education, but little is known about cognitive problems in young childhood cancer survivors (survivors). This study compared cognitive problems between survivors and their siblings, determined if cognitive problems decreased during recent treatment periods and identified characteristics associated with the presence of a cognitive problem in survivors. METHODS As part of the Swiss Childhood Cancer Survivor Study, a questionnaire was sent to all survivors, aged 8-20 years, registered in the Swiss Childhood Cancer Registry, diagnosed at age <16 years, who had survived ≥5 years. Parent-reported (aged 8-15 years) and self-reported (aged 16-20 years) cognitive problems (concentration, working speed, memory) were compared between survivors and siblings. Multivariable logistic regression was used to identify characteristics associated with cognitive problems in survivors. RESULTS Data from 840 survivors and 247 siblings were analyzed. More often than their siblings, survivors reported problems with concentration (12% vs. 6%; P = 0.020), slow working speed (20% vs. 8%; P = 0.001) or memory (33% vs. 15%; P < 0.001). Survivors from all treatment periods were more likely to report a cognitive problem than were siblings. Survivors of CNS tumors (OR = 2.82 compared to leukemia survivors, P < 0.001) and those who had received cranial irradiation (OR = 2.10, P = 0.010) were most severely affected. CONCLUSION Childhood cancer survivors, even those treated recently (2001-2005), remain at risk to develop cognitive problems, suggesting a need to improve therapies. Survivors with cognitive problems should be given the opportunity to enter special education programs. Pediatr Blood Cancer © 2014 Wiley Periodicals, Inc.

A Novel Memory-centric Architecture and Organization of Processors and Computers

The modern computer systems that are in use nowadays are mostly processor-dominant, which means that their memory is treated as a slave element that has one major task – to serve execution units data requirements. This organization is based on the classical Von Neumann's computer model, proposed seven decades ago in the 1950ties. This model suffers from a substantial processor-memory bottleneck, because of the huge disparity between the processor and memory working speeds. In order to solve this problem, in this paper we propose a novel architecture and organization of processors and computers that attempts to provide stronger match between the processing and memory elements in the system. The proposed model utilizes a memory-centric architecture, wherein the execution hardware is added to the memory code blocks, allowing them to perform instructions scheduling and execution, management of data requests and responses, and direct communication with the data memory blocks without using registers. This organization allows concurrent execution of all threads, processes or program segments that fit in the memory at a given time. Therefore, in this paper we describe several possibilities for organizing the proposed memory-centric system with multiple data and logicmemory merged blocks, by utilizing a high-speed interconnection switching network.

Does bounded rationality lead to individual heterogeneity? The impact of the experimentation process and of memory constraints

In this paper we explore the effect of bounded rationality on the convergence of individual behavior toward equilibrium. In the context of a Cournot game with a unique and symmetric Nash equilibrium, firms are modeled as adaptive economic agents through a genetic algorithm. Computational experiments show that (1) there is remarkable heterogeneity across identical but boundedly rational agents; (2) such individual heterogeneity is not simply a consequence of the random elements contained in the genetic algorithm; (3) the more rational agents are in terms of memory abilities and pre-play evaluation of strategies, the less heterogeneous they are in their actions. At the limit case of full rationality, the outcome converges to the standard result of uniform individual behavior.

Memory in contracts: the experience of the EBRD (1991-2003)

The objective of this paper is to identify the role of memory in repeated contracts with moral hazard in financial intermediation. We use the database we have built containing the contracts signed by the European Bank for Reconstruction and Development EBRD between 1991 and 2003. Our framework is a standard setting of repeated moral hazard. After having controlled for the adverse selection component, we are able to prove that client reputation is the discrimination device according to which the bank fixes the amount of credit for the established clients. Our results unambiguously isolate the effect of memory in the bank's lending decisions.

Memory of Recessions

This paper reviews the evidence on the effects of recessions on potential output. In contrast to the assumption in mainstream macroeconomic models that economic fluctuations do not change potential output paths, the evidence is that they do in the case of recessions. A model is proposed to explain this phenomenon, based on an analogy with water flows in porous media. Because of the discrete adjustments made by heterogeneous economic agents in such a world, potential output displays hysteresis with regard to aggregate demand shocks, and thus retains a memory of the shocks associated with recessions.

A test of long memory hypothesis based on self-similarity

This paper develops a new test of true versus spurious long memory, based on log-periodogram estimation of the long memory parameter using skip-sampled data. A correction factor is derived to overcome the bias in this estimator due to aliasing. The procedure is designed to be used in the context of a conventional test of significance of the long memory parameter, and composite test procedure described that has the properties of known asymptotic size and consistency. The test is implemented using the bootstrap, with the distribution under the null hypothesis being approximated using a dependent-sample bootstrap technique to approximate short-run dependence following fractional differencing. The properties of the test are investigated in a set of Monte Carlo experiments. The procedure is illustrated by applications to exchange rate volatility and dividend growth series.

The Biblioteca de Catalunya: working for the present and the future

The Biblioteca de Catalunya (BC) was created in 1907 by the Institut d’Estudis Catalans (IEC). In 1914 the Mancomunitat de Catalunya gave the library its condition of cultural and public service, open to researchers and scholars. The library underwent several changes as a consequence of political events, along the most of 20th century. In 1981 it was recognized by law as national library and it recovered its foundational aim of gathering, preserving and disseminating the bibliographical output of Catalonia and the production related with the Catalan linguistic field. As the proud host of ANADP2, the BC wants to show the attendees to the conference how, since 2004, has positioned itself to face the challenge of the new informational and technological paradigm. The library strategy for oncoming years includes giving open and free access online to the digitization of many of his collections through the portals MDC (Digital Memory of Catalonia), ARCA (Old Catalan Serials Archive) and Google Books project; the creation of the Web Archive of Catalonia and, as the last step in the consolidation of its policy, a high-security preserving repository named COFRE, based on the international guidelines and initiatives and the experience of the BC itself.

Memory and power : two movements

The institutions that work with the preservation and diffusion of cultural heritage - be them archive, libraries, museums, art galleries or cultural centres - present a certain discourse about reality. To understand this discourse, composed by sound and silence, by fullness and emptiness, by presence and absence, by remembrance and forgetting, an operation is implied, not only with the enunciation of speech and its gaps, but also the comprehension of that which causes to speak, of who is speaking and of the point whence one speaks. Preservation and destruction, or, in another way, conservation and loss, walk hand in hand in the arteries of life. As suggested by Nietzsche (1999, p.273), it is impossible to live without loss, it is entirely impossible to live avoiding destruction to play its game and drive the dynamics of life on. However, by means of a kind of tautological argument, one often justifies preservation by the imminence of loss and memory by the threat of forgetting. Thus, one ceases to consider that the game and the rules of the game between forgetting and memory are not fed by themselves and that preservation and destruction are not opposed in a deadly duel, but instead they complement one another and are always at the service of subjects that build themselves and are built through social practices. To indicate that memories and forgettings can be sown and cultivated corroborates the importance of working towards the denaturalisation of these concepts and towards the understanding that they result from a construction process also involving other forces, such as: power. Power is a sower, a promoter of memories and forgettings.

A note on Chambers's "long memory and aggregation in macroeconomic time series"

Chambers (1998) explores the interaction between long memory and aggregation. For continuous-time processes, he takes the aliasing effect into account when studying temporal aggregation. For discrete-time processes, however, he seems to fail to do so. This note gives the spectral density function of temporally aggregated long memory discrete-time processes in light of the aliasing effect. The results are different from those in Chambers (1998) and are supported by a small simulation exercise. As a result, the order of aggregation may not be invariant to temporal aggregation, specifically if d is negative and the aggregation is of the stock type.

Robustness of stationary tests under long-memory alternatives

This paper investigates the presence of long memory in financiaI time series using four test statistics: V/S, KPSS, KS and modified R/S. There has been a large amount of study on the long memory behavior in economic and financiaI time series. However, there is still no consensus. We argue in this paper that spurious short-term memory may be found due to the incorrect use of data-dependent bandwidth to estimating the longrun variance. We propose a partially adaptive lag truncation procedure that is robust against the presence of long memory under the alternative hypothesis and revisit several economic and financiaI time series using the proposed bandwidth choice. Our results indicate the existence of spurious short memory in real exchange rates when Andrews' formula is employed, but long memory is detected when the proposed lag truncation procedure is used. Using stock market data, we also found short memory in returns and long memory in volatility.

Limited memory and the essentiality of money

This paper investigates the relationship between memory and the essentiality of money. We consider a random matching economy with a large finite population in which commitment is not possible and memory is limited in the sense that only a fraction m E(0; 1) of the population has publicly observable histories. We show that no matter how limited memory is, there exists a social norm that achieves the first best regardless of the population size. In other words, money can fail to be essential irrespective of the amount of memory in the economy. This suggests that the emphasis on limited memory as a fundamental friction for money to be essential deserves a deeper examination.